Engine International Showcase 2009

2010showcase

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Case studies Aston Martin | Bowman Power

Fuji Heavy Industries | DSMLotus Engineering | Gomecsys

A&D Technology | AVL ContiTech and many more

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45 A&D TechnologyA new system that integrates combustion analysis and automated calibration

48 AVl A range of e-motor, battery,

and hybrid testing solutions is helping suppliers and OEMs

59 SySTec A highly innovative technology for producing a new generation of diamond-like carbon coatings

cASe STuDieS06 ASTon MArTin Two powertrain partners have

joined forces to create one of the best sounding �� enginesding �� engines

12 Fuji heAVy inDuSTrieS Subaru’s latest boxer diesel

powertrain meets stringent Euro 5 emissions regulations without compromising power output, fuel economy or N�H

18 loTuS engineering Electric and hybrid vehicles may soon transmit synthesized external noise to alert pedestrians to their approach

22 MenzoliT A look at how composite materials are playing an important role in the latest powertrain systems

30 BowMAn Power By harnessing waste heat, exhaust energy recovery systems can improve fuel economy and cut emission levels of diesel engines

36 AuBerT & DuVel – erASTeelThe key to designing the eco-friendly IC engines of the future lies in advanced materials, often involving innovative metallurgical processes

40 conTiTechA detailed analysis of new sustainable and performance-minded solutions for all tasks involving carrying of media

42 goMecSyS Introducing the third-generation GoEngine technology, which boasts numerous performance, emissions output, and overall fuel economy benefits

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CONTENTS02

Editor Dean SlavnichChief sub-editor Alex BradleySub-editor William BakerEditorial assistant Bunny RichardsProofreaders Christine Velarde, Frank MillardArt director Craig MarshallArt editor Ben WhiteDesign team Louise Adams, Andy Bass, Anna Davie, James Sutcliffe, Nicola Turner, Julie WelbyProduction manager Ian DonovanProduction team Joanna Coles, Carole Doran, Lewis Hopkins, Emma Uwins

Contributors John Challen, Brian Cowan, Matt Davis, Jonathan Lawson, Adam Gavine, Max Glaskin, Maurice Glover, Burkhard Goeschel, Graham Heeps, Greg Offer, Mike Magda, Jim McCraw, Keith Read, John Simister, Saul Wordsworth

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Engine Technology International magazine is published four times per year by UKIP Media & Events Ltd, Abinger House, Church Street, Dorking, Surrey, RH4 1DF, UK. The magazine is distributed by US mail agent, Clevett Worldwide Mailers LLC, 7 Sherwood Ct, Randolph, NJ 07869. Periodicals postage paid at Dover, NJ 07801. POSTMASTER: Please send address changes to Engine Technology International, 19 Route 10 East, Bldg 2, Unit 24, Succasunna, NJ 07876. USPS Periodicals Registered Number 016-699.

The views expressed in the articles and technical papers are those of the authors and are not endorsed by the publisher. While every care has been taken during production, the publisher does not accept any liability for errors that may have occurred. This publication is protected by copyright ©2010. ISSN 1460-9509 Engine Technology International. Printed by William Gibbons & Sons Ltd, Willenhall, West Midlands, UK.

63 DSMA new innovation is delivering weight, noise and system cost benefi ts in oil sump pplications

76 SOGEFI FILTRATIONInnovations in fi lter designs are helping car makers to reduce critical emissions output

78 F-DIESEL A leading Chinese supplier is offering high-speed, high-power advanced diesel engine R&D

FEATURES26 OEM INTERVIEW: WOLFGANG STROBL

BMW’s general manager of CleanEnergy on building cars powered by hydrogen

50 OHIO STATE UNIVERSITY Design of the world’s fastest hydrogen fuel cell electric vehicle: Buckeye Bullet 2

66 IMPERIAL COLLEGE LONDON A student engineering team is gaining extensive experience in the design and development of alternative fuel race cars

74 UNIVERSITY OF WISCONSIN-MADISON An online program is bringing a Masters degree in engineering within easier reach of working engineers around the world

80 BIG END Our verdict on some of the new vehicles we’ve driven recently


News and exclusives | Supplier directory | Recruitment |Industry opinions | Image gallery | Read the latest issue online

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■ Welcome to this very special edition of Engine Technology International. For this, our fi rst offering of the new decade, we’ve decided to do things a little differently: this entire issue is written by the industry for the industry. That’s right, the copy you hold in your hands is brimming with technical papers written by engineers at car maker, supplier and academic level.

We start with a piece from Aston Martin’s chief powertrain engineer, evaluating the company’s awesome One-77 heart (p6). That’s followed by a technical insight into what Fuji Heavy Industries and Subaru engineers are doing to bring to market a second-generation Boxer Diesel engine that offers better fuel consumption, fewer emissions and far greater power (p12). Oh, and be sure to read an interesting piece from Lotus Engineering that focuses on safety issues related to hybrid and electric vehicles (p18).

As well as the latest on activity at OEM level, this special edition boasts white papers from some of the leading global suppliers,

from Tier 1 right through to Tier 3. There’s an exclusive piece from Gomecsys, revealing details about the company’s innovative third-generation powertrain (p42). That’s followed by a white paper on combustion analysis from A&D in the USA (p45). And before A&D, be sure to read Bowman Power’s theory on how diesel engines for heavy-duty vehicles can be greatly improved by using exhaust recovery systems (p30). Other supplier papers come from ContiTech (p40), AVL (p48), Systec (p59), DSM (p63) and Sogefi -Filtration (p76). Signing off this issue is a very interesting piece from F-Diesel on the quality, high-tech diesel development opportunities in China (p78).

But before you get to F-Diesel’s piece, there are three academic papers I’d like to bring to your attention. The fi rst is a rare insight from Imperial College London – one of the UK’s leading engineering institutions – on its motorsport development program (p66). Joining Imperial in our University Focus, from across the Atlantic, is Ohio State

University, which details its involvement in the Buckeye Bullet 2 program (p50), and then there’s also the University of Wisconsin-Madison, which is celebrating its virtual world academic services (p74).

And do we stop there? Of course not. There’s more – some 48 pages more, in fact – in the form of a free Transmission Technology International supplement, a must-read for all engineers concerned with gearboxes, drivetrains, and general engine development. Enjoy!

Dean Slavnich editor

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Up and Running!

Case study: aston martin06

When two powertrain teams came together to develop a new V12, they created the best-sounding Aston Martin to date

Powertrain partners


Author: Dr Brian Fitzsimons, chief engineer of powertrain, Aston Martin

123

HEADINGCAsE stuDy: AstoN MArtIN07


08

CASE STUDY: ASTON MARTIN

■ The One-77 is Aston Martin’s take on a defi nitive sports car, and one that epitomizes everything that the UK brand is about, from state-of-the-art technology to the all-new V12 and the eye-catching design.

From an engineering perspective, the One-77 V12 project was an automotive engineer’s dream come true. The brief was to make Aston’s V12 engine as ‘extreme as possible but right for the road’. Yet, as highly motivating as such a brief was, with management setting tough targets for the powertrain team to meet, it posed serious engineering and technical challenges for the powertrain engineers, as highlighted in Tables 1 and 2.


Swept-volume increase 5,935cm3 to 7,312cm3

Bore increase 89mm to 94mmStroke increase 79.5mm to 87.8mmMaximum power speed 7,500 rev/minMaximum mechanical engine speed increase 7,300 to 7,750 rev/minF1-derived dry-sump lubrication systemNew port design built upon F1 experienceVariable valve timing on intake

best skill set and experience that would complement the Aston Martin powertrain engineering team, possessed experience of delivering production engine designs and components, and understood Aston Martin’s manufacturing and quality-process functions. Thus Cosworth, which had previously delivered the Vanquish S cylinder-head design, was selected as the engine-design partner for the V12 project.

The benefi t of a good team cannot be underestimated, because it is that team – and not technologies such as the best CAD and analysis packages – that delivers the engine. The team was led by Aston Martin’s Chris Porritt as the project manager, with design direction coming from Cosworth’s Bruce Wood. Integration into the One-77 was led by Aston Martin’s Richard Morley, with a joint

team of module owners, designers and development engineers. Engine and vehicle calibration was performed by the Aston Martin calibration team, led by John McLean.

Engine specifi cationIt was clear from the start of the One-77 program that the basis of the engine was to be the 6-liter V12 that powers both the DBS and V12 Vantage models. This engine has a fantastic track record but perhaps even more importantly, it had considerable development potential. Therefore the team set out to maintain as much of the original architecture as possible and only change features that enabled them to ‘make the V12 as extreme as possible but right for the road’.

The usual fi rst step with such a project was using 1D simulation to design the primary engine parameters to meet the performance targets. Because the basis of this engine was to be the Aston Martin V12, there was a considerable amount of already-validated data, so a good level of confi dence existed in the model from the beginning.

The opportunity was the brief to examine considerably more extreme design options for this unique application. The modeling results led to the primary engine specifi cation in Table 3, and this gave a power and torque curve that appreciably exceeded the targets – a good position to be in at the start of the design process!

Engine featuresEach major design decision was analyzed and evaluated using Table 3: Early simulation modeling results of Aston Martin’s One-77 V12 powertrain

Power output more than 700bhpTorque output more than 700NmSpecifi cation naturally aspirated V12 engineInstallation as low and rearward as possibleRange more than 300 milesNVH the best-sounding Aston Martin

Table 2: Aston Martin’s initial engine target for the One-77 development project

0-60mph under 4 secs 0-100mph under 7 secsTop speed more than 200mphVehicle mass less than 1,500kgCd less than 0.4Power/weight more than 450PS/TWeight/power less than 2.3kg/PSOperating environment -15°C to +50°C

Table 1: Aston Martin’s initial vehicle target for the One-77 development project

The Cosworth co-developed V12 One-77 heart generates 750bhp at 7,500rpm The 7.3-liter powertrain will sit 257mm further rearward of the One-77 front axle

“It was judged that Cosworth had the best skill set and experience that would complement the Aston Martin engineering team”

There were, however, some unquantifi able targets during the project, as shown in Tables 1 and 2. Terminology such as ‘more than’ and ‘less than’ was used to encourage the engineering team not to stop when the engineering target was achieved, taking the V12 and the One-77 beyond the project’s set goals.

As an independent sports-car manufacturer, Aston Martin is free from any corporate prejudice or skill-set bias that can build up in an engine-design function over time. This gave the engineering team tremendous freedom to select the best skilled partner to deliver the new V12. It was judged that Cosworth had the

CASE STUDY: ASTON MARTIN09

experimental data, analysis data, surrogate data, and experience. Naturally, the most diffi cult to quantify was experience, but it was a priceless input to the design process. Each design decision was evaluated for impact on performance, friction, package, mass, aesthetics, emissions output and cost.

One of the most critical systems in achieving the initial performance target was the intake system. It was here that meticulous attention to detail yielded very good results. At the heart of the One-77 engine was an F1-derived port design that specifi cally targets fl ow velocity at 7,500 rev/min. The shape of the port gives this subsystem a free-fl owing path to the combustion chamber.

The ports and combustion chamber were fully machined, enabling them to be accurately manufactured, free from defects that might disturb the ideal function, and repeatability. The actuation of 12mm intake and 11mm exhaust valves was by lightweight, direct-acting buckets coated with DLC giving ultra low friction at high speed. Analysis and experiment showed that roller-fi nger followers would have lower friction at lower engine speed where cycle fuel economy is important, but this engine focused on lower friction at the high-power end.

the port gives this subsystem a free-fl owing path to the combustion chamber.

important, but this engine focused on lower friction at the high-power end.


The volume in the intake manifold plenums around the induction trumpets was maximized to allow good airfl ow and take full benefi t of the gas dynamic tuning. This led to a bigger and heavier intake manifold but to counteract this, the plenums were manufactured in lightweight carbon fi ber.

Four throttle bodies were used, two on each bank, symmetrically arranged. This enabled optimal fl ow distribution and maximized the V12’s sound quality.

Cylinder block and crankcaseThe cylinder block has retained the original architecture bore spacing of 102mm but the bore has been increased to 94mm.

Replacing the original pressed-in cast-iron liners, the bore has been plasma-iron sprayed onto the parent metal, using the Sulzer Metco RotaPlasma process. This has given a weight saving, improved the

cooling performance, and increased the engine knock resistance. The block casting was modifi ed slightly to accommodate the increase in stroke from 79.5mm to 87.8mm. This manufacturing process continued to use the DBS engine CosCast process – a pressurized sand-cast process, developed by Cosworth. In addition, the casting was subject

to the hot isostatic process to give improved fatigue properties, with the increased engine performance. On the bottom end, the cast-iron main bearing caps were replaced with aluminum for mass reduction and redesigned to seal the chambers for the dry-sump system. The original cross-bolting structure was retained.

The eight-counterweight crankshaft setup was replaced with a 12-counterweight design. A forged-steel V12 crankshaft is a considerable proportion of the engine mass. However, extensive design analysis resulted in a fully optimized 12-web crankshaft that, despite increases in both stroke and engine speed, yielded a saving of 1.4kg in mass. Original bearing pin diameters were retained and to increase fatigue life, design changes were made to the fi llet radii on the big-end pins. The crankshaft web radius was machined to match piston motion and minimize clearance to minimize engine height.

Piston-guided steel connecting rods were used rather than the crank-guided rods that feature in the Aston DBS engine. This change reduced friction levels and gave a 1.2% power gain. The piston-guided steel connecting rods also reduced connecting-rod mass.

The pistons were entirely new and constructed from a bespoke forging with a 32mm skirt

Meticulous attention was paid to the air intake subsystem to ensure V12 met performance goals

Above and right: The V12 features four throttle bodies – two on each bank – which are symmetrically arranged

length. FEA and race experience was used to optimize the piston design for minimum mass, resulting in a mass reduction of 24g over the original assembly, despite being considerably more loaded. The piston pins were DLC coated to further reduce friction levels, and the standard oil-cooling jets were retained.

The packaging challengeThe packaging of a 7.3-liter V12 unit in a front-engined sports car is a considerable challenge. Engine performance dictated that the intake system should not suffer any compromises due to the package. The key enabler to achieve this was the new dry-sump system.

There was considerable experience and expertise coming from the Aston Martin V8 Vantage application, as well as Cosworth’s F1 and WRC projects. The result was a dry-sump system that enabled the engine to sit 100mm lower in One-77 than in any of its other Aston Martin applications. This produced a 16.5mm clearance from the intake system to the body, at the top of the engine.

The key features of the dry-sump system are fully sealed bays in the oil pan, each of which are scavenged by a separate scavenge pump with a scavenge ratio of 4:1. The scavenge pumps feed the oil

tank via a swirl pot, and thereafter, a de-aeration plate. The oil is then picked up by the oil-pressure pump, which retains the original V12 oil-pump internals, but in a bespoke housing to facilitate a chain drive for the scavenge pumps. The installation process was diffi cult; other major achievements included maintaining the same oil volume as the standard wet sump-system V12, and achieving aeration of only 7%.

Exhaust systemThe One-77’s exhaust system provided a major packaging challenge, because the engine position was too low for the exhaust to pass below the bell housing. Making things all the more challenging was the Euro 5 emissions target, the 700bhp, and the One-77’s carbon-fi ber construction. The only solution was to route the exhaust manifold out to the side of the car and along the sills.

The next hurdle was to defi ne the best compromise between engine performance and emissions. Two scenarios

were evaluated and both of these designs had equal length primary pipes with good catalyst inlet conditions, which represented a considerable

geometrical achievement.Performance evaluation of the

exhaust manifolds were outlined in the development project and this is a good example of where the fi nal decision was not in favor of the higher power output. Instead, a shorter primary system was selected

5 emissions target, the 700bhp, and the One-77’s carbon-fi ber construction. The only solution was to route the exhaust manifold out to the side of the car and along the sills.

The next hurdle was to defi ne the best compromise between engine performance and emissions. Two scenarios

were evaluated and both of these designs had equal length primary pipes with good catalyst inlet conditions, which represented a considerable

geometrical achievement.Performance evaluation of the

exhaust manifolds were outlined in the development project and this is a good example of where the fi nal decision was not in favor of the higher power output. Instead, a shorter primary system was selected

because of its emissions potential, and the compromise on performance was quantifi ed, understood, and accepted.

Induction systemA high-performance sports car needs to have a very effi cient air path. The solution was a very elegant one. The front longitudinal structure in carbon fi ber was designed to perform three functions without compromise: provide the air path, be a structural crash member, and provide mounting for the front fender. This helped provide an effi cient, high volumetric-fl ow path to the quad throttles located mid-car from the twin airboxes at the front, and demonstrated the integrated functionality that was critical to achieving the best result for One-77.

Such developments, as well as attention to detail, allowed for all targets to be met. More than 700bhp and more than 700Nm of torque was achieved, the engine was positioned as low and rearward as possible, and it is the best-sounding Aston Martin to date. ETi

Engine weight was high on the development agenda. As a result, the V12 tips the scales at just 260kg

thereafter, a de-aeration plate. The oil is then picked up by the

bespoke housing to facilitate a

same oil volume as the standard

achieving aeration of only 7%.

because of its emissions

Above: AM says some 80% of parts on the One-77 engine are new Below: The lightweight cam cover

“Piston-guided steel connecting rods were used rather than the crank-guided rods that feature in Aston DBS”

10

CASE STUDY: ASTON MARTIN


Invented for life?YesInnovations from Bosch.

Innovations from Bosch. ‘Invented for life’ is our mission. We develop innovations that respond today to the global problems of the future. That’s why many of the 14 patents Bosch registers every day contribute to progress in renewable energies, emission reduction and fuel economy. Doing our share for a better future. www.bosch-environment.com

CASE STUDY: FUJI HEAVY INDUSTRIES12

Subaru’s latest boxer diesel engine meets Euro 5 emissions regulations without compromising power output, fuel economy or NVH performance

Next-generationboxer diesel


■ In recent years, being environmentally friendly has become an important feature for new passenger cars. Diesel cars, which produce lower CO

2

emissions, dominate new car sales in Europe, taking a 50% share of the market. It was for this reason that in 2008, Subaru launched the Euro 4-compliant boxer diesel Legacy. Employing a common-rail system and a variable nozzle-type turbocharger, the Subaru boxer diesel offers output performance and fuel economy that are well suited to an AWD vehicle platform.

The 2008 boxer diesel won praise from consumers, the media and the industry alike. However, the development concept of the second-generation boxer diesel was to satisfy Euro 5 regulations while maintaining the engine output performance, fuel economy, and NVH characteristics of the Euro 4-compliant boxer diesel.

For Euro 5, the NOx and PM elements must be reduced by at least 30% and 80% respectively from the Euro 4 levels. To realize this, the development team reduced PM by improving the DPF that is employed in the

Authors: Kenji Harima and Yoshinori Nakajima, engine design department, Fuji Heavy Industries



New Legacy has been launched with the second-generation diesel boxer – an engine that offers excellent

NVH behavior, engine performance and fuel economy

14

CASE STUDY: FUJI HEAVY INDUSTRIES


four-cylinder boxer petrol engine, the boxer diesel employs a diagonally split connecting rod and a different method of assembly. This has minimized the increase in the cylinder block deck height. Furthermore, the piston height is kept compact by employing high-strength aluminum alloy pistons. The cylinder head comprises four valves and center injection. Employing proprietary fuel spray injectors with short overall length, the cylinder-head height is lower than in the boxer petrol, successfully maintaining the

engine overall width equivalent to that of the petrol.

In general, diesel engines are much heavier than their petrol counterparts. To minimize the increase in weight, the overall length of the boxer diesel engine is shorter than that of the boxer petrol. The bore pitch was shortened by 14.6mm compared with the boxer petrol, giving an overall length of 353.5mm, which is 61.3mm shorter than the boxer petrol. In total, the boxer diesel achieved a weight reduction of 10kg compared with a typical 2-liter four-cylinder diesel powertrain, through the compactness of short overall length and width, combined with the balancer shaft-less structure coming from the good noise and vibration characteristics and the weight reduction of various parts.

The turbocharger is of a variable nozzle type, which controls the vane opening around the exhaust turbine according to the operating

range, giving highly effi cient supercharging in all ranges. The turbocharger is located under the engine to ensure good exhaust gas conversion and give a low center of gravity. The characteristic dynamic performance of the Subaru is realized through the lowered center of gravity and enhanced supercharging response.

The oxidation catalyst and the DPF are located directly downstream of the turbocharger. This layout enables the catalyst to warm up more quickly, securing the exhaust gas conversion performance in a wide operating range.

Aftertreatment systemThe aftertreatment system for the Euro 5-compliant boxer diesel incorporates several new features. The DPF system located directly downstream of the turbocharger, equipped as standard in the fi rst-generation boxer diesel for the Forester, has improved PM converting

“In total, the boxer diesel achieved a weight reduction of 10kg compared with a typical 2-liter four-cylinder diesel powertrain”

Table 2: Further important differences between the two boxer diesel powertrains

Table 1: Comparing the technical features of the two boxer diesel powertrains

Forester and Impreza models, and reduced NOx by developing advanced combustion control.

Engine confi gurationThe main confi guration of the new engine is based on the conventional boxer diesel. The benefi t of the boxer engine is that it enables a compact, lightweight and highly rigid design compared with an inline four-cylinder unit. It also offers excellent NVH behavior, engine performance, and fuel economy.

To extend the stroke, but keep the overall width of the engine equivalent to that of a


Compliant with Euro 5 legislation, the all-new boxer diesel engine (below) has been launched in the new Legacy (left)

capability. For emissions conversion, especially the NOx, fi ve features have been adopted: large EGR cooler; new fuel injection system; new combustion chamber shape; low compression ratio; and lift sensors for variable nozzle-type turbocharger actuators.

The major difference in the regulations between Euro 4 and Euro 5 is in the permissible emission levels of PM and NOx. The improvement of air utilization factor is effective for the reduction of PM emissions, and the decrease of combustion temperature is effective for the reduction of NOx emissions. To restate: the two keywords for PM and NOx reduction are combustion temperature and air utilization factor. In general, when a large volume of EGR

gas is introduced into the combustion chamber with a large-sized EGR cooler, the low temperature levels of the EGR gas helps to reduce NOx emissions. However, the decreased combustion rate often impairs the thermal effi ciency and leads to poor fuel economy. Moreover, the increased EGR rate lowers the air utilization factor in the cylinders and increases PM emissions. A large-sized EGR cooler is good for NOx reduction, but could worsen fuel economy and raise PM.

Furthermore, the new fuel injection system has an increased fuel pressure at normal range, with eight holes that are 9% smaller in diameter than those of the previous system. This promotes the

atomization of fuel spray and the increase of air utilization factor, leading to PM reduction and quick, effi cient combustion for better fuel economy. Yet there is a risk of increased combustion temperature levels and NOx emissions.

For Euro 5 compliance, Subaru chose to employ a large-sized EGR cooler and a new fuel injection system. Engineers also set out to develop a combustion chamber shape that maximizes the benefi ts of the large-sized EGR and the new fuel injection.

The shape of the combustion chamber is an important factor, because it is where the atomized fuel meets oxygen to cause combustion. The development team used CAE analysis of space and time to investigate the combustion of the fuel injected into the chamber.

In the Euro 5 system, where the diameters of the chamber lip and the chamber cavity are extended and the cone angle is optimized, it is clear that the PM generation in the cavity is reduced. In addition, the high Table 3: The degree of infl uence of each combustion factor for NOx and PM emissions

PM consistency area at 26° ATDC (after top dead center) has been considerably reduced compared with the Euro 4 system. This is the result of PM oxidation, which has been promoted by the improvement of air utilization factor.

The intake airfl ow is another important factor for controlling fuel diffusion in the combustion chamber and the combustion rate. The air is taken in through a helical port and a tangential port to create a swirl inside the combustion chamber and to diffuse the fuel so that oxygen and fuel are mixed. The optimum velocity and streamline are where the neighboring fuel


sprays are not made to overlap each other by the swirl. The engineering team also focused on the lowered compression ratio, which is aimed at decreasing the combustion temperature to reduce NOx. The combustion temperature has been decreased by about 100°C. As well as satisfying the Euro 5 NOx limit, the infl uence of the low compression ratio on theoretical thermal effi ciency and on PM emissions has been minimized.

The development team concluded that the best compression ratio for the Euro 5 system is 16.0, compared with 16.3 in the Euro 4 system.

The fi nal feature to be introduced is the lift sensors for the variable nozzle-type turbocharger actuator. The lift sensors help to keep the boost pressure high at low load range, thereby raising the oxygen concentration in the combustion chamber and improving the air utilization factor. This leads to a reduction in PM emissions.

To maximize the effects of these fi ve new hardware items, the development team conducted a series of elaborate

and highly accurate calibration tests. The engine control strategy is made up of a complicated matrix structure compared with the Euro 4 system. The infl uence on the combustion varies according to combinations of parameters such as the pressure, timing, the number and the timeperiod of fuel injections. In addition, by optimizing the EGR rate control and boost pressure control at all operating ranges, the best performances of engine output, fuel economy, and emissions conversion have been achieved.

Figure 1 illustrates a graph that compares cylinder pressure, rate of heat release and cylinder temperature levels for the Euro 5 and Euro 4 systems. The operating conditions are third gear, 1,600rpm, which is equivalent to 25mph vehicle speed, and mid-level load of 750kPa indicated mean effective pressure (IMEP).

In the Euro 5 system, as more EGR gas is introduced and the combustion rate is controlled at a much faster level compared with the Euro 4 system, the overall thermal effi ciency level is

vastly improved, and as a result of this, the combustion temperature level is maintained at about 100°C lower.

Table 3 shows the degree of infl uence of each combustion factor for NOx and PM emissions respectively. The reduction of NOx and PM was realized by the combination of fi ve hardware components and seven combustion factors. As can be seen, the infl uence of combustion factors on NOx and PM varies. By balancing these complex factors, the new engine cut NOx by about 60%.

NVH performanceThe Euro 5 boxer diesel maintains the NVH standards of the Euro 4 system while also satisfying the Euro 5 regulation.

In general, the high combustion pressure of diesel engines leads to greater combustion noise and engine vibration. The boxer diesel reduced such NVH and maximized its potential for stillness, realizing smooth and lively driving with low noise and vibration in all ranges from idling to high speed, without

CASE STUDY: FUJI HEAVY INDUSTRIES

Figure 2 compares the cylinder pressure levels of the two boxer diesel powertrains

16


The second-generation boxer diesel boasts several new features including a new DPF system (right)

Figure 1 compares the rate of heat release of the two boxer diesel powertrains

the need for balance shafts. The combustion noise, which could have deteriorated by making it Euro 5 compliant, has been maintained at the same level as the Euro 4 system, after reviewing the number of multi-stage injections and calibration strategies for driving conditions.

The second-generation boxer diesel has been launched into the European market, satisfying the Euro 5 regulation while maintaining the engine output, fuel economy, and NVH and vibration characteristics of the fi rst-generation engine.

The development of this engine had two outcomes. First, fi ve new features have been introduced: a large-sized EGR cooler; a new fuel injection; a new combustion chamber shape; low compression ratio; and lift sensors for the actuators of variable nozzle-type turbocharger. These features, in combination with the DPF, enable the second-generation boxer diesel to meet Euro 5. The second outcome is that the quietness and fuel economy of the fi rst-generation engine have been maintained. ETi

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CASE STUDY: LOTUS ENGINEERING18

Lauded for helping to drive down emissions and improve fuel economy, electric and hybrid vehicles are now facing criticism for being too quiet in urban environments

NVH optimization


■ Electric and hybrid vehicles have been coming in for criticism recently from a group of consumers that don’t drive: the blind. The lack of noise from hybrid vehicles at slower speeds when running on electric power creates a hazard, according to blind and partially sighted people, who rely on their ears to determine whether it is safe to cross the road or walk through a parking lot.

It is not only the blind and partially sighted who experience greater risk: the problem has became evident to the engineers at Lotus Engineering, as the hybrid and electric vehicles the company develops for its long list of clients move slowly around its workshops. Even fully sighted people use audible

cues to judge the proximity of moving vehicles. In response, Lotus Engineering has developed a system to synthesize external sound from electric and hybrid vehicles to overcome what is seen as a growing problem facing pedestrians.

Similar concerns were expressed some years ago when almost silent electric trolley buses replaced trams in some US cities, meaning that pedestrians, familiar with the noise of tram wheels on rails, would not notice the much quieter buses approaching. For the same reason, commercial vehicles in the UK have used external noise systems for some time. Buzzers, beepers, and synthesized voice systems are regularly heard when reversing

to warn pedestrians. And now the issue is receiving attention from legislators.

In Washington DC, a bill is going through Congress to establish a minimum noise requirement for hybrid and electric vehicles. The EU is set to follow suit, with the European Commission also reviewing proposed legislation. This could make the need for added noise on hybrid and electric vehicles a legislated requirement for all vehicle manufacturers. And this is where Lotus’s technologies come in.

External electronic sound synthesis is a part of the Lotus suite of patented active noise control (ANC) technologies, which comprises three main systems: electronic sound

synthesis, road noise cancellation, and engine order cancellation. Each of these systems can be used individually or in combination.

Lotus began developing its ANC technology – a method of canceling out one noise by generating an equal and opposite noise – more than 15 years ago. The major obstacle to wide-scale adoption at that time was that established solutions to intrusive noise issues were widely available in the form of conventional passive NVH material or other more established engine technologies, such as balance shafts. The fact that these alternative solutions usually added mass to the vehicle or consumed more energy was not seen as important, and ANC, although feasible, never succeeded as a commercial product.

Over the past few years, however, things have changed. The computing power required to run the ANC system is now

Hybrid and electric vehicles have been questioned in terms of safety – especially in urban environments

The new Evora, but are Lotus engineers working an all-electric derivative?

Author: Jamie Turner, Lotus Engineering


frequently present on a single chip in high-end audio systems at a fraction of the cost of 15 years ago. The need to save energy and reduce CO

2 levels

means that the conventional approaches that sidelined ANC are now less desirable.

Harman International, a manufacturer of premium

in-car audio systems, has acquired the exclusive rights to develop the Lotus ANC technologies for volume production. This represents a major step toward making

this technology to customers.

Although ANC is now viably

advantageous for more effi cient vehicles generally, the emergence of hybrid and electric vehicles has created new applications. Most obviously, the emergence of hybrid and electric drive vehicles has led to the reapplication of internal electronic sound synthesis to create external electronic sound as a means to enhance pedestrian safety. Amid growing claims that these almost silent vehicles present a danger to pedestrians and other road users such as cyclists, by generating an external warning sound of the right character, not only can these vehicles be made safer, but also the character of the brand identity can be enhanced.

Of course, hybrid and electric vehicles do make a sound in the form of road noise, but this noise is generally heard when the vehicle is travelling at speeds of more than 20mph. At slower

speeds, they are very quiet. A recent study by the University of California found that electric and hybrid vehicles had to be about 65% closer to a person than a car with a gasoline engine before the person could judge the direction of travel correctly. Which also begs the question, what is a hybrid or electric vehicle supposed to sound like?

Interestingly, while road users ideally want a sound that is instantly recognizable as an approaching vehicle, manufacturers and owners of these vehicles want a distinct electric vehicle sound. This has led to a series of new sounds being generated that are

“Lotus Engineering has developed a system to synthesize external sound from electric and hybrid vehicles to overcome what is seen as a growing problem”

CASE STUDY: LOTUS ENGINEERING19

Some are calling for EVs to generate the same sound as IC-powered cars

As well as NVH matters, Lotus Engineering is also working on eco-friendly systems, such as this range-extender unit

20

CASE STUDY: LOTUS ENGINEERING

futuristic enough to be distinguished from a conventional engine, but have enough similarities with existing engine sounds to be recognizable as an approaching vehicle. Careful positioning and design of the speaker ensure the sound is projected forward from the vehicle in a fairly tight beam – exactly where it is needed as a warning to other road users – without generating undue extraneous noise.

As part of the agreement between Lotus Engineering and Harman International, a Toyota Prius has been used as a technology showcase. Three out of the four technologies are used in conjunction with each other, removing audibly unpleasant frequencies and adding external sound to increase pedestrian safety.

For engine order cancellation, input signals from the engine are fed into the electronic controller, as are sound signals, measured by microphones located in the cabin. The software algorithms of the controller then calculate what sound is needed to provide cancellation and the speakers of the in-car entertainment system are used to put this into the cabin. This process takes only a few hundredths of a second and is continuously repeated, seamlessly and instantaneously adapting to changes in speed or road condition.

The second system is internal electronic sound synthesis, the purpose of which is to enhance sound in the cabin. The control system uses the engine speed signal, a throttle position sensor


and the in-car entertainment system to add sound. This can be particularly useful to disguise the change in frequency during the switch from battery power to engine. This system also forms the basis of external electronic sound synthesis.

To synthesize the engine sound, a road speed signal is taken from the vehicle. The sound is transmitted through a waterproof loudspeaker system positioned behind the front grille. Sound can be synthesized from the rear of the vehicle in the same way, to give a warning when the vehicle is reversing.

When a car is operating on the electric motor only, throttle and speed-dependent synthesized sound projects an engine sound in front of the vehicle. If the hybrid’s engine starts operating at higher speeds or throttle demands, or lower battery levels, the control system automatically stops the external synthesis. When the powertrain control system switches the car back to running on the electric motor only, the synthesis controller instantly reactivates the system. The process is completely automatic and the driver hears almost none of the additional sound.

To generate a realistic sound, recordings of a suitable donor engine are made and analyzed to establish the characteristic frequencies at various engine speeds. These frequencies are

then entered into the synthesis controller in the form of a voice that outputs the sound via an amplifi er and the loudspeakers.

Alternatively, more futuristic sounds for electric vehicles can be created using sampled sounds and generated waveforms. As proven in the Toyota Prius demonstrator, used together or individually, the ANC technologies offer numerous benefi ts.

With increasing use of common platforms shared between manufacturers, ANC offers a way to provide a premium high-end product from a mainstream donor platform with a high level of commonality, and to provide some level of brand differentiation through acoustics. In addition, the normal acoustic development between different body styles (sedan, wagon, coupe) can all be reduced because the ANC system adapts to all vehicle types with minimal retuning.

So although the benefi ts and relevance of ANC are numerous, the agreement reached between Lotus and Harman International is hugely signifi cant. For the fi rst time, through the combined expertise of Lotus and Harman, there is a defi ned route to production for the world’s car makers. It will not be long before these systems are improving the refi nement and safety of future vehicles. ETi

Toyota Prius has been used as a technology showcase. Three out of the four technologies are used in conjunction with each

audibly unpleasant

order cancellation, input signals from the engine are fed into the electronic controller, as are

and the in-car entertainment system to add sound. This can be particularly useful to disguise the change in frequency during the switch from battery power

Emissions reduction and safety enhancement are key areas at Lotus

Based on a Proton Gen.2 with a 1.6-liter gasoline engine, the Lotus EVE technology demonstrator features a start/stop system, full parallel hybrid drive and a CVT unit

“To synthesize the engine sound, a road speed signal is taken from the vehicle. The sound is transmitted through a waterproof loudspeaker system positioned behind the front grille”

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Case study: Menzolit22

A look at how new composite materials are playing an important role in the latest powertrain systems

n Since the invention of the steam engine, iron and steel have been the materials of choice in engine design. Aluminum and magnesium were added when they became available for mass production. Today, engines incorporate many materials, including polymers, which must withstand increasingly higher temperatures, stresses and loads.

Industrial composites are a relatively new class of low-density, high-performance materials that appeared on the market after the invention of glass fibers in the late 1930s.

Precise performance


Author: Peter Stachel, director of technology, Menzolit

Figure 1: the composite’s position within the polymeric materials

“Today, engines incorporate many materials, including polymers, which must withstand increasingly higher temperatures, stresses and loads”

However, most composites cannot be molded into complex shapes; they are difficult to process and unsuitable for high volume production.

But if they are modified through the addition of fibers, fillers, catalysts and stabilizers, a material called sheet molding compound (SMC) or bulk molding compound (BMC) can be made. Such fiber-reinforced composites combine the best of two worlds: they provide high strength per weight for structural performance, and easily flowing resins give flexibility in molding.

Composites have applications in boats, cars, trucks and even in challenging areas such as primary aircraft structures. These materials are cost effective for high volume production and can be molded to any shape using established processes such as injection or compression molding. Figure 1 shows the position of composites and thermoset composites within the field of polymeric materials.

These simple-to-mold materials have applications within the electrical, construction, sanitary, truck and car industries. However,



they can also be applied to engine components, replacing metals such as steel and aluminum, magnesium and zinc. Metal casting processes are well established, but their net shape capabilities are limited and they require precision machining. Some components such as oil pans and valve covers may be made from stamped steel, but again precision and shape are limited.

SMC and BMC are glass fiber reinforced for strength and stiffness, and based on a thermoset resin to provide resistance to the high temperatures and corrosive substances encountered in an engine. Figure 2 shows shear modulus versus temperature for various materials.

SMC and BMC are usually molded in different ways. SMC is a sheet-like material sold in coils. It is compression molded on hydraulic presses, which results in higher mechanical properties than BMC, which is more likely to be injection molded. Molding pressure is low, at about 100 bar, but this is

a natural choice for molding larger components on big engines such as truck engines.

BMC is produced in volume for headlight reflectors, more than 90% of which are made from this material. High levels of precision, excellent surface appearance, high service temperature, short cycle time, efficient molding, and low material costs make it an ideal choice for this application.

BMC is sold in the form of slugs that require specific feeding equipment for injection molding; apart from this feeding mechanism, the injection machines are similar to standard injection molding equipment.

Mechanical strength is largely controlled by the type and quantity of fibers added. Glass fibers are most commonly used for reasons of cost and performance. The amount added depends on whether SMC or BMC is used and the automotive application for which it is intended.

For example, an oil pan on a heavy-duty engine would use SMC with about 40% glass

content, and a valve cover on the same engine may be made with only 25% glass to reduce material costs and improve the flexibility of the mold. On a smaller engine, the same components may be made of BMC with less than 25% glass. In both cases, the resin and basic formulation may be identical; only the fiber content

and compounding process differ, which is an efficient way to customize the process.

Thermosets typically have excellent temperature resistance, with no melting or softening. They also exhibit good media resistance, since their 3D molecular network makes it difficult for low molecular weight materials to penetrate.

typical BMC formulation

Figure 2: stiffness versus temperature levels

24

Case study: Menzolit

This intrinsic behavior means that should an engine overheat, there is no sudden failure of SMC or BMC; even if the powertrain catches fire, an SMC or BMC oil pan will have greater flame resistance.

The greatest advantage of plastic or composite materials is the ability to integrate functions into as few parts as possible. In contrast with a metal stamping process, compression molding of SMC and injection molding of BMC allow a true 3D flow, enabling complicated shapes to be manufactured.

SMC and BMC can also be tailored to ensure zero shrinkage at molding. Since the processing temperature is lower than for casting metals (150°C compared with 900°C), dimensional changes at cooldown to room temperature are small. The coefficient of thermal expansion (CTE, 10 x 10-6m/mK) is in the same range as steel, making very precise moldings possible. Tolerances of H5 to H6 can be achieved, eliminating the need for costly machining, in turn giving significant cost savings compared with metal components. A polymer material will perfectly copy a mold cavity. Undercuts can be handled by means of sliding cores, threads or metal bushings molded in to provide fastening elements. This makes


SMC/BMC the true net shape material, combining complex geometry with high levels of precision.

SMC/BMC also offer great cost advantages. Any material that is based on expensive raw materials (oil) or high energy consumption (aluminum and magnesium) will reflect global changes in material prices. The petrochemicals-based raw materials content of SMC/BMC is less than 30%. Filler and glass are based on minerals available nearly everywhere in the world, and the quantities and energy required to produce SMC/BMC are small. As a result, SMC/BMC prices increased by only 9% between 2000 and 2008, while the price of aluminum and crude oil tripled within the

same period. And although metal prices declined sharply at the beginning of the 2008-09 crises, it is certain that they will soar once again.

The cost of processing depends on the number of steps in the manufacturing process and the amount of labor needed to produce a finished component. Compression molding and injection molding are mature technologies that have been optimized for many years. So when they are applied to SMC/BMC, one can take advantage of proven and efficient manufacturing processes. However, there is one key difference: Thermosets molding requires deflashing. During molding, the low-viscosity resin of the

Compression molding of sMC

the injection molding machine for BMC

“Current applications in the European market for SMC/BMC include oil pans for Daimler and Volvo’s heavy-duty trucks”


compound’s matrix leaks into the gaps within the mold, creating thin flash lines. In the case of BMC, these flash lines can be removed with standard pellet blasting. The SMC process can also make use of deflashing equipment, and this includes such things as abrasive brush or a high-speed milling device.

Market research suggests that fuel costs will continue to rise. Governments around the world have implemented legislation that calls for drastic reductions in emissions. It is known that a reduction in weight results in a reduction of fuel consumption and emissions. So a 100kg weight saving results in roughly half a liter less fuel consumed. Low-weight design at low cost will be the challenge facing most vehicle and engine designers in the coming years. The density of steel and aluminum are 7,85 and 2,7 respectively, but the density of SMC/BMC is 1,8, meaning a weight reduction of 30-40% is possible.

Current applications in the European market for SMC/BMC include oil pans for Daimler and Volvo’s heavy-duty trucks, both of which are in their second generation. On smaller engines, subsystems and components such as valve covers and throttle bodies constructed from BMC are increasingly popular.

Menzolit is a pioneer in SMC technology, with plants in Italy, Spain and the UK. Its products are mainly used in electrical and transportation applications. The company is well known for its Class A SMC products for global automotive and truck applications, as well as its long-standing experience in the electrical industry. ETi

the dimensional change due to Cte at cooling down after molding

oil pan made of sMC for heavy truck engine

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Engine Technology 12.10.2009 12:28 Uhr Seite 1

OEM intErviEw: BMw


26

Lone rangerDespite announcing plans for numerous hybrid and electric applications, BMW remains committed to building cars powered by hydrogen

Words: John Challen

OEM IntErvIEw: BMw


27

explains Wolfgang Strobl, the general manager of CleanEnergy and Effi cientDynamics within BMW’s research and technology group. “So in 2000, the technical status was frozen and a quality process was implemented. At the moment, the engine can be driven by gasoline, but in the long run we will optimize the engine dramatically and focus on just one fuel: hydrogen.”

There is little doubt that the Hydrogen 7 project is one of the greatest powertrain challenges BMW has set itself. Strobl admits that problems regarding fuel delivery mean his research and development team is currently exploring both

■ While most car makers are hurriedly pushing through plug-in electric vehicle programs that will result in a new breed of eco-friendly vehicles hitting our roads within the next fi ve years, BMW’s hydrogen-fueled vision remains much the same as it did at the turn of the millennium. Now armed with data from four million test miles completed in a fl eet of 100 7 Series sedans equipped with 6-liter hydrogen-fed IC engines, BMW’s powertrain engineers are about to take hydrogen technology to the next level, in the form of several new, exciting projects.

“In the Hydrogen 7’s engine development, the most important element is quality,”

CELL OUT?BMW says that development on its auxiliary power unit (APU) for fuel cell cars continues – despite work on this system having started over a decade ago with United Technologies. “One fuel cell can provide 100W, which means you need 500 cells for one system,” explains Strobl. “That is more complex in the long run, but for replacing the alternator and battery, a small fuel cell APU would be an interesting development. “Our objective is to do the APU series production development for the Hydrogen 7. We have solved many problems recently and have achieved lifetime figures of 5,000 hours, which was one important task.” Strobl also claims that the BMW engineers have got over the hurdle of cold starts and operating in subzero temperatures. However, as patents are still pending, nothing can be announced until next year.

“In the Hydrogen 7’s engine development, the most important element is quality”

WOLFGANG STROBL, GENERAL MANAGER OF BMW CLEANENERGY AND EFFICIENTDYNAMICS

Having overcome several major engineering challenges and undertaken fl eet trials in California, BMW is now ready to move to the next stage with its hydrogen-fueled vision

BMW is currently looking at optimizing the weight of the Hydrogen 7’s tank system

compressed and liquid hydrogen forms. And whichever route the company takes will affect storage, so tank development is a priority for Strobl: “We are currently running a research program to optimize the weight of the tank system, using a high-pressure gas tank and a liquid hydrogen gas tank system.

“The combination of both technologies enables the tanks to have better boil-off rates. The normal lightweight liquid hydrogen system will always be a problem for customers who don’t drive regularly [because of evaporation rates], and for those customers we are developing another system, which is a combination of a hydrogen tank

OEM INTERVIEW: BMW


28

Rumors from Munich suggest that the next hydrogen car will be based on a 3 Series

and a pressurized tank system.” According to Strobl, this latter tank can extend boil-off times from 3 days to 10 days.

The tanks are constructed of a combination of steel and carbon-reinforced plastics, and BMW is currently testing different combinations, with the fi nal product likely to appear in two years’ time. “The specifi c volume for the cryogenic pressurized tank will be similar to Hydrogen 7’s [8kg/170-liter] tank,” says Strobl. “For each type of hydrogen storage we need four times the volume used for gasoline and up to seven times the volume needed for compressed hydrogen, either at 350 bar or 700 bar.” Strobl says the aim is to use no more

than 1kg of hydrogen per 100km, giving a theoretical range of 800km.

Although rumored to be based on a 3 Series, the next BMW hydrogen car has not yet been offi cially decided, but one thing is certain: it won’t be another 12-cylinder-powered vehicle, says Strobl. “In 2000, we needed a big car to accommodate the extra hydrogen tank. We needed a bigger engine for bi-fuel operation and we were looking at 30-50kW of power per liter, which meant the 6-liter engine in the Hydrogen 7 Series offered around 190kW. We will most likely replace the 12-cylinder engine with a smaller, four-cylinder engine.”

But results from BMW’s recent evaluations show that there is a possibility that the engine could be smaller still. “Our research on single cylinder data has enabled us to reach maximum power output of 100kW per liter of engine displacement,” reveals Strobl. “Our specifi c value is normally the number of kilowatts per liter of engine displacement, and we reached

50kW on a single cylinder (500cc), which means

we reached 100kW per one liter of engine displacement. You usually need two

cylinders for one liter.” Based on the

existing engine in the Hydrogen 7, this would give the car 600kW and nearly 1,000bhp! “We are aiming for a 100-200kW engine, so a

two- or three-cylinder engine will be enough

in the long term.” ETi

BMW will trade the current 12-cylinder for a smaller four-cylinder in the next hydrogen technology demonstrator

FROM HYDROGEN TO HYBRIDSBefore the excitement of fuel cells is fully realized, BMW – like many others – is investing time and capital in creating hybrid products. The plug-in Vision Effi cientDynamics concept may have been the star attraction at the Frankfurt Motor Show, but for Strobl’s colleague Wolfgang Nehse, department manager in charge of drivability and functional assessment, the main focus is the ActiveHybrid 7 Series and X6 models. The two vehicles use different hybrid systems, with the 7 Series deploying the same mild hybrid architecture that features in Mercedes’ S400 petrol-electric. Perhaps most noteworthy is that the ActiveHybrid 7 is the fi rst car in the world to combine a V8 petrol engine, a three-phase synchronous electric motor, and eight-speed transmission (supplied by ZF). Meanwhile, the full hybrid ActiveHybrid X6 features two electric motors – one mounted on each axle – and can run in electric-only mode at up to 60km/h for up to 3km.

Nehse explains why two different systems were used in the cars: packaging and driver preference. “One reason we decided to use the (mild hybrid) system in the 7 Series was because there is not much room in a normal limousine.” The battery pack needed to allow the possibility of electric-only driving, says Nehse, which would take up too much valuable space in the trunk. “It was a case of a 40-liter battery pack, versus 120-liter.

“The other reason [for the two systems] is that with a four-wheel-drive car you can recuperate energy with all four wheels; with a two-wheel-drive [in the sedan] there is only one driven axle, so you don’t need as much power from the generator or electric engine.”

These two vehicles highlight BMW’s hybrid capabilities, but Nehse is also aware of future goals and products. “The next step will be to introduce a hybrid version of the 5 Series, probably using the 7 Series’ mild hybrid system.” Based on the savings of up to 20% that are made on the ActiveHybrid models, Nehse says a hybridized 5 Series would consume as much fuel as a current 3 Series.

Batteries are a major talking point at BMW, with Ni-MH cells in the X6 and Li-ion for the 7 Series. And then there is lithium polymer, as seen in the stunning Effi cientDynamics concept. “Lithium polymer is too early in its development at the moment to be used on these cars,” warns Nehse. “Nickel-metal hydride and lithium-ion are both on the market. We know with lithium technology there is a high power output and maybe in turn this technology will have a bigger capacity to drive effectively. If we look at all the cars able to drive with electric energy, they all use Ni-MH. “At the moment this is the only way to drive electronically, but using lithium technology we are developing other systems, ultimately to ensure future hybrid cars have safe batteries.”

OEM INTERVIEW: BMW


29

CASE STUDY: BOWMAN POWER30

■ Diesel cycle engines remain the de facto technology for powerplant and commercial vehicles from 150kW. Yet 30% of the energy in the fuel is lost through the exhaust system. In today’s market it is becoming essential to recover some of this wasted energy and put it to good use. Exhaust heat recovery (EHR) systems are playing an increasingly important role in the emissions and fuel consumption challenges facing today’s heavy commercial vehicle (HCV) and off-highway markets globally. Turbocompounding using a high-speed electric turbogenerator (TG) is now a technically mature solution that can address this need for improved fuel economy.

The Sankey diagram inFigure 1 illustrates the energy path of a classic diesel engine. Energy is lost in several forms, one of the largest being through the hot exhaust gases.

With the cost of fuel rising on an ever-increasing trend, and CO

2 emissions featuring in new

legislation, recovery of some of that wasted exhaust energy is a logical step in making these engines more effi cient. Indeed, the primary running cost for end users of these engines is the fuel itself, and OEMs have been under pressure for many years to implement strategies and technologies to improve fuel consumption levels.

Engine manufacturers have introduced different technologies over the years to improve fuel effi ciency. Some of these technologies involved the

Diesel development for HCVs


recovery of wasted energy. Many HCV OEMs have introduced mechanically coupled turbocompound systems to their engine range, notably Scania in 1995 and Volvo in 2002 with its D12-500TC, followed by Iveco and then Daimler in 2008, when it introduced the fi rst of its global HDEP engines, the DD15 from Detroit Diesel.

There are essentially four key drivers for introducing EHR systems on modern engines: improved fuel consumption and reduced CO

2 emissions; reduced

harmful exhaust emissions; improved engine power output and power density; and assisting the migration toward a more-electric vehicle

When it comes to the fi rst two benefi ts – improved fuel consumption and reduced CO

2

emissions – it is clear that if an EHR system is able to harness ‘wasted’ exhaust energy and feed that back into the crankshaft, for the same power output, the engine will not need as much

of the combustible fuel as an engine without an EHR system. In addition, CO

2 is widely held

to be a contributory factor in global warming. Governments across the world are committed to reducing the annual CO

2

emissions tonnage, of which land vehicles represent a considerable portion. CO

2 is

an inevitable result of the combustion of carbon fuels; the amount formed is therefore in direct proportion to the amount of fuel burned. Legislation to reduce CO

2 and indeed fuel

consumption from HCVs already exists in Japan and is pending in the EC and USA.

The second key driver to EHR technology focuses on harmful exhaust emissions. Elements such as NOx, CO and PM are all considered harmful to human life. Subsequent rounds of government legislation have been demanding ever-reducing pollution levels from engines, as shown in Figure 2. These reductions have not been achieved without a

Figure 1: The typical fuel energypath in a diesel-powered vehicle

Improving the fuel economy of a diesel engine while using exhaust energy recovery systemsAuthor: Jon McGuire, engineering director, Bowman Power

CASE STUDY: BOWMAN POWER31


corresponding fuel economy penalty, negating or suppressing advances made elsewhere. Nevertheless, with all other factors equal, if an EHR system enables less fuel to be combusted, then it logically follows that harmful exhaust emissions will correspondingly be reduced. EHR therefore represents a way of clawing back fuel effi ciency that may have had to be sacrifi ced to achieve a cleaner exhaust.

The third advantage to EHR is power output. Conversely, if the same level of combustible fuel is used and the recovered exhaust energy is fed back into the crankshaft, it is clear that the engine would have a larger power output than the non-EHR engine. This could be used to extend the capability design envelope of an existing engine, or open up engine downsizing opportunities.

Finally, EHR as a technology also paves the way for a future where there are far more electric vehicles. OEMs, for example, are becoming extremely interested in more-electric vehicles for three main reasons: effi ciency improvements by electrifying auxiliaries (such as the cooling fan and water pump); more fl exible packaging (especially when it comes to subsystems such as air conditioning); and interworking with a mild hybrid system.

The four drivers previously mentioned are strong reasons for any engine OEM to implement an EHR system. In practice the interaction between all these factors is complex, and

there are other parameters such as combustion effi ciency, air/fuel ratios, in-cylinder temperatures and pressures and combustion chemistry. Advanced simulation, measurement and analysis techniques enable engine makers to seek the best balance of all the above parameters, but considerable engine testing is still needed to crystallize the optimum confi guration.

As described, the EHR system is designed to recover heat energy in the exhaust system and convert it into useful energy for the vehicle. Existing mechanical turbocompounding (m-TC) systems convert some of the exhaust heat energy into mechanical energy that is fed back to the crankshaft via a hydraulic coupling and gear train. Bowman has successfully developed an alternative electric turbocompounding (e-TC) method that converts some of the heat energy in the exhaust into electrical energy.

The underlying technology is based on integrating a compact

high-speed electrical machine with a high-performance turbine stage. Other confi gurations include putting the electrical machine on the shaft of the turbocharger to electrically assist the turbocharger process (such as the motor assist). However, this paper focuses more on the combination of a turbine-driven generator, applied to the exhaust stream to create ane-TC system.

Most electrical generators run at a low speed (typically below 3,600rpm) and are therefore relatively large and heavy. Thee-TC technology uses very compact, high-speed (>30,000rpm), high-effi ciency (>98%) electrical alternators, which can be directly added to the high-speed turbine shaft (and do not need a gearbox) for use as a generator.

However, although there is a considerable exhaust heat energy available in the exhaust,

Figure 2: A comparison of stringent emissions regulations in the European market

The illustration above charts Bowman TG turbine effi ciency levels

Bowman Power’s TurboGen technology

32

CASE STUDY: BOWMAN POWER


a turbine requires a pressure drop to convert this heat into mechanical (rotational) work. Simple introduction of a TG into an existing engine will therefore introduce additional exhaust back-pressure that will increase the pumping work done by the engine, reducing its power and effi ciency. The net increase in the combined power output (engine + TG) is therefore rather limited, and may even be negative as a result of this situation .

The key to success is in careful redesign of the turbomachinery to make optimum use of the available exhaust manifold pressure. Bowman achieves this by using very high-effi ciency turbo machinery, that is typically fi ve-10% above traditional HCV technology.

For a given total pressure drop, the use of higher-effi ciency turbocharger technologies (such as compressor and turbine sections) means less exhaust energy given up to the turbocharger system, and therefore a greater amount of energy is available to the TG. Separately maximizing the TG turbine stage effi ciency levels further increases the generated TG power.

With a well matched solution, the net result is a system with the same total power output, a lower overall exhaust temperature – the exhaust having given up energy to generate power – and lower fuel consumption. The same technical principles – the conversion of exhaust energy to shaft rotational energy – apply also to m-TC systems. An e-TC system differs only in how that rotational energy is transmitted back to the drivetrain.

The gain in fuel economy levels for m-TC systems has generally proved to be modest, with the saving being around 3%. This is essentially because the turbine wheel is constrained to operate at a speed with a fi xed relationship to the crankshaft speed (aside from fl uid coupling slip) and therefore cannot run at the optimum speed for highest effi ciency for much of the operating envelope.

However, the m-TC system may absorb power at some load

conditions while generating power at other conditions. In contrast to this output, the e-TC method of extracting power electrically enables the turbine wheel of the TG to run at controlled speeds designed to optimize the effi ciency of energy recovery, and can provide a much higher fuel saving as an average across a typical vehicle duty cycle.

Figure 3 shows actual engine full load test results achieved by John Deere with a Bowman TG system applied to a Deere 9-liter Tier 3 off-road engine. The total system power at each operating speed, (crankshaft torque) is the same for the base engine or the (engine + e-TC) system, but the latter demonstrates a 10% brake specifi c fuel consumption (BSFC) reduction across a broad operating speed range.

Much of the data generated from vehicle OEM testing and development is confi dential and cannot be publicly released. However, data that can be released includes that recently gathered from fi eld trials in a PowerGen application, showing a brake thermal effi ciency level of 47% for an engine running on biogas fuel. This information has been used to calibrate a GT-Power model of the engine.

The results show that them-TC gives maximum power at the 100% load points. However, different trucks have different load cycles and a highway HCV spends a lot of its life at sub-75%. The important factor to note is that e-TC has a better BSFC at all load cycles and

shows great improvement at the loads that most vehicles see most of the time. This means that more fuel is conserved more of the time.

For some off-highway vehicle applications, there may be a desire to optimize energy recovery for 100% load cycles. In this instance, e-TC is still an informed choice over m-TC.

At certain conditions, the e-TC system conserves as much as three times more fuel than the m-TC does over the base engine. Even at all the other conditions, the e-TC system beats the m-TC in BSFC % improvements. What is not shown is that m-TC systems are an energy consumer at low loads and idle, therefore pulling down the average BSFC.

A properly designed e-TC system does not consume energy at any stage, it just varies how much fuel saving is achieved. The result of the above improves the cycle effi ciency levels.

Exhaust heat recovery technologies have proven stability with reciprocating engines for several decades. The m-TC system has been used in the HCV market since the early 1990s but with only a limited fuel consumption benefi t to fl eet owners around the world.

New turbine and e-machine technologies, together with available hybrid architectures, mean e-TC systems are now a viable next engineering step in improving the brake thermal effi ciency of a modern diesel engine. ETi

Figure 3: BSFC comparison – base versus e-TC engine (9-liter capacity)

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THE INTERNATIONAL ENGINE OF THE YEAR AWARDS 2010Taking place on the second day of Engine Expo, the highly acclaimed International Engine of the Year Awards have become some of the most sought-after accolades in the industry, with the winners often using the logo as a centrepiece of their television and advertising campaigns. The ceremony attracts the most senior engine designers, executives and journalists from all over the world, and takes place in an open-seated area within the exhibition halls.

CASE STUDY: AUBERT & DUVAL – ERASTEEL36

The key to achieving successful designs for new eco-friendly IC engines lies in advanced materials – often involving innovative metallurgical processes

■ It is most likely that IC engines will still power cars, trucks, trains, and ships, exclusively or in combination with electric engines, for a few more decades. But for this to happen, IC engine technology will have to evolve, and the multiple innovative designs that will emerge will require innovation in the fi eld of materials, and particularly steels.

What will be the drivers for IC engine innovation? A fi rst driver is performance, and in

Advanced materials for future IC engines


particular performance that focuses on the environment. The necessary technological changes to meet the increasingly stringent environmental regulations – emissions and pollutants control, use of biofuels, downsizing, or even novel IC engine designs – will call for materials that can cope with increasingly aggressive operating conditions.

In addition to this trend, there are specifi c markets where reliability, safety, or performance

will be key to the success of powertrains such as heavy-duty diesels and racing engines.

IC engines are mature systems in a very competitive market, but cost is – and will continue to be – the other major driver. The recent raw material price surge has shown how highly alloyed grades could negatively impact product cost. Cost reduction can be achieved through optimization to reduce the content of expensive elements or through the use of alloyed grades that enable engineers to avoid using expensive PVD coatings.

Although in most cases these contradictory drivers – cost and performance – must be taken into account, advanced alloys can still be relevant solutions, with advanced not only meaning optimized grades/compositions but also state-of-the-art metallurgical manufacturing processes.

Does this mean that new grades/processes need to be developed each time the standard material toolbox is not suffi cient? There is no easy answer to such a question. From a steel supplier’s perspective, grade innovation strongly depends on volumes. Applications with large volumes can justify specifi c grade developments. This is typically the case for valves or light-duty engine parts where yearly volumes reach several thousand tons. In such cases material development is done through partnerships between suppliers and OEMs, and sometimes even with exclusivity agreements. For smaller volume applications, the

approach is different and the designer must often go to great lengths to source existing materials. Grade development can to some extent still be triggered but this becomes generic and the supplier in this case must spend time targeting several markets. Historical examples of such material transfers include: high-speed steels for diesel injection parts, originally designed for cutting tool/cold work markets; martensitic stainless steels for gasoline injection parts, developed for bearings or knives; or Ni-based alloys for exhaust line parts, originally developed for aerospace.

Melt size infl uences the critical volume for grade development. For continuously cast grades, the key fi gures are in the hundreds of tons, while in air-melted ingot cast steels, some tenths of tons are to be considered. Special melting processes such as VIM/VAR remelting (typical for aerospace or Formula 1) or powder metallurgy have lower critical masses (of up to 10 tons).

To fi nd the right grades and treatments for the multiple parts of innovative engines, suppliers with experience of a range of materials are extremely valuable, as they have the ability to guide the designer through the materials jungle and provide valuable feedback during development or early market launch. One such example represents one of the most challenging areas for engineers: diesel injection. Advanced steels/surface treatments are used in pumps and injectors,

Author: Dr Angelo Germidis, development manager, Aubert & Duval – Erasteel

The innovative ASP process, fi rst established in 1972 by Erasteel, consists of gas atomization of metallic powders followed by hot isostatic compaction

Case study: aubert & duval – erasteel37


which are often the most severely loaded parts of the system. To meet emission requirements, temperatures of the system have increased to 400°C and more, and pressure has also increased to 3,000 bar and more. Numerous families of grades that are either hardened or case hardened/nitrided, cover a wide range of automotive applications including carburizing steels, nitriding steels, tool/high-speed steels (conventional or PM) and martensitic stainless steels (conventional or PM).

Carburizing grades are used because they are cost-effective, suitable for mass production,

and provide a deep case depth. Carbon contents range between 0.15-0.2% and 0.4-0.7%, with various amounts of Si, Ni, Mo, and Cr being added.

A common handicap for these grades is temperature resistance, which does not exceed 200°C (between 150°C and 250°C). They tend to soften, which restricts the choice of PVD coatings that can be applied. A special grade called FND has been developed by Aubert & Duval, which enables an extra operating temperature of 100°C. This is achieved mainly through additions of Si and Mo. The slightly increased Ni content improves hardenability, enabling

gas quenching and therefore limiting distortion. Another possible solution is CX13VD, a martensitic stainless steel with 11.5 w% Cr. Its mechanical properties are close to FND, but after carburizing it displays corrosion resistance up to 58 HRC. In very specific designs, the carburized part can be locally removed at annealed state by machining to fully use the corrosion resistance of the grade. Both grades are tempered typically at 250°C, and easily up to around 200°C.

At the other end of the range, ASP grades, hardened or nitrided, are very interesting materials for engineers to look

at when resistance is needed and temperature requirements exceed 350°C, and tool steels/nitriding steels cannot cope. ASP is an industrial process established in 1972 with the trade name of Erasteel. It consists of gas atomization of metallic powders followed by hot isostatic compaction.

The ASP process brings major microstructural benefits for alloyed steels, typically high-speed steels that include high amounts of carbon and carbide forming alloying elements such as W, Mo, and V: ASP 2023, 2030, 2060 are most popular for cutting and cold work tools. But continuous improvements in cleanliness have recently opened up the components markets for a range of ASP grades: ASP 2012, ASP 2017, ASP 2005, ASP 2004, and Bimax 42 are all very interesting candidates with increasing levels of carbides. As a result of all this development, it becomes clear that the ASP process can be used for classes of alloys other than HSS/TS, and is also suitable for martensitic stainless steels and superalloys.

The main microstructural benefits of the ASP process are the drastic reduction of carbide size to a very few microns – up to 10 times less than for ingot cast material – and the isotropy and lack of macrosegregation, even for large sizes. In addition, this process enables the exploration of compositions that cannot be ingot cast. All ASP grades consist of a steel matrix, but different amounts and types of carbides provide different property combinations, such as

the above illustrations show it is possible to achieve 1,400 Hv for components made of bimax42. such a high level provides automotive engineers with a cost-effective alternative to ceramics in terms of hardness levels and overall wear resistance

all: Carburizing grades are now used because they are cost-effective, suitable for mass production in the automotive industry, and also provide a deep depth

38

Case study: aubert & duval – erasteel

hardness, impact resistance, and abrasion resistance. The very high cleanliness levels are achieved through process development and control based on investigations involving destructive testing such as ultrasonic testing, LOM/automated SEM analysis, and fatigue testing, and allow for a generic resistance to brittle and fatigue failure. The average cleanliness is comparable to remelted steels. These general features give ASP grades several exciting key characteristics for engine designers.

Most ASP grades can be tempered at high temperatures, typically 560°C for PM high-speed steels, and this makes them stable at up to 500°C for hundreds of hours. In some cases, ASP grades can even be pushed up to 600°C if temperature excursions are not so frequent.

Wear resistance – particularly abrasion and erosion resistance – is achieved through overall high hardness and the amount/size and types of carbides. The hardest are the MC carbides, which are rich in V, followed by the M6C carbides, rich in Mo and W, and finally MxCry carbides found in the stainless grades or in most Cr alloyed tool steels. Chromium carbides can be hard enough for less abrasive environments.

The ASP process enables an outstanding combination of high hardness and impact resistance to be achieved, typically above 53-4 HRC, and

terms of mechanical properties as diesel injection, but this powertrain area has its own challenges in terms of corrosion resistance in connection with the use of flexfuels.

A very successful grade is N-Alloyed X15TN, which is closely related to the XD15NW grade that was developed for aerospace bearings. Its composition enables it to reach 59 HRC and it can be tempered at low (180°C) and high (500°C) tempering temperatures. It has an outstanding corrosion resistance and almost outperforms the high-temperature tempering grade 440°C. The trick is the limitation of carbon content and the addition of N. This mixture, in combination with a very sophisticated remelting process control and a very strict conversion scheme, provides exceptional homogeneity for this kind of grade, as well a strictly bound inclusion content ensuring exceptional reliability.

Such examples of material development for the automotive industry show how advanced materials – often involving advanced metallurgical processes – can be key to achieving successful designs at controlled cost for the new environmentally friendly IC engines of the future, thereby creating value for engine developers, suppliers, OEMs, and for society as a whole. ETi


a very high strength – ASP grades are the strongest metallic alloys of all on the market.

One of the most interesting properties is fatigue resistance. The small carbide size together with the high cleanliness level give exceptional fatigue resistance at a high number of cycles. Typical fatigue resistance in rotating bending at 20 million cycles ranges between 1,100MPa and 1,450MPa, depending on the grade and the heat treatment. It must be emphasized, however, that the experience of using such grades in such applications is relatively new; more work needs to be done to quantify and improve the reliability of cleanliness for PM grades. Using the potential of these materials for brittle fracture or fatigue sets very high requirements on surface finish. The potential is there and component testing should determine whether these materials are suitable for any given application.

An unexplored property is the specific modulus. Grades with a significant volume fraction of carbides, particularly V carbides, can display a fairly high Young’s modulus for a moderate density, giving specific moduli E/ρ up to 25% higher than high-performance construction steels. This gives ideas for decreasing component weight for motorsport applications in particular.

Another way to use these materials for applications such as rollers is to use nitriding.

Nitriding of ASP steels is not a very easy process to control, as the white layer formed is brittle and the case is shallow, typically 50µm. However, if performed according to the best practices, it enables 1,100-1,200 HV and high compressive stresses to be easily reached, which improves the component’s lifespan. It is even possible to achieve 1,400 HV for components made of Bimax42, providing a cost-effective alternative to ceramics in terms of hardness and wear resistance levels.

PM MSS can be considered when corrosion resistance and serious mechanical properties at certain temperatures are needed. Two grades are available today: APZ10 and RWL34, a PM version of martensitic steel 618. An advantage of the PM structure is that it limits the extension and intensity of the local Cr depletion around phases such as carbides, hence decreasing the risk of pitting. There are enough carbides to provide good abrasion resistance, and this enables the range to expand.

It is important to note that all applications and grades do not require or profit from the specifics of powder metallurgy. Particularly in the field of stainless steels, many exciting properties can be achieved with other melting techniques.

Gasoline injection is a field that is not as demanding in

the graph above illustrates the temperature level advantages to the asP process

the graph above highlights the reduction in the number of large non-metallic inclusions

Case study: ContiteCh40

Author: Mario Topfer, ContiTech AG

There are some ideal sustainable and performance-oriented solutions for all tasks involving the carrying of media

n Sustainable solutions that satisfy requirements with regard to performance, comfort, and safety: this is what the auto industry is in search of for its present and future customers. ContiTech Fluid Technology already has the right solutions and is able to offer optimally matched components for all tasks involving the carrying of media for everything related to modern high-performance assemblies and the powertrain: from high-performance charge-air hoses to cooling and lubrication systems for the engine, turbocharger, and the transmission.

The Panamera premium grand tourer from Porsche is a good example, demonstrating that performance and environmental awareness no longer have to be at odds with each other. With this model, the sports car maker together with

ContiTech successfully managed to reduce fuel consumption by 20% in comparison with the Cayenne model, which has a similar engine. It helps that the Panamera has to carry around 400kg less, thanks to elegant solutions such as transmission oil cooler lines by ContiTech.

The transmission oil cooler lines now weigh in at a mere 900g – nearly a 50% reduction in weight, and 10% lighter than Porsche had originally requested. “We had to blaze new trails in the development phase,” explains Dr Michael Hofmann, head of automotive products at ContiTech Anoflex in Caluire, France. Together with the customer, an impressive solution was quickly found. The line consists of a thin-walled aluminum tube. In addition, the number of components was reduced. All of the connections are formed and not soldered,

High-performance engine technologies


and the hose portion was reduced to a minimum length. The tube had to be adapted to extreme installation space requirements; special tools also had to be developed to manufacture the tight bending radii. In the ContiTech Anoflex testing laboratory, the prototypes were thoroughly tested in a series of vibration, service life, and aging tests within a very short period of time. “The ports do not require special measures to be connected to the automatic transmission and oil cooler,” says Hofmann. As a result of this, the extensive know-how is available to be used by future vehicle generations.

Anoflex also produces hydraulic lines for the Panamera’s active chassis with roll stabilizer with an oscillating motor. Anoflex supplies the entire underbody hose system,

above: in the lubrication of the turbo, the rigid tubes developed by Contitech engineers close the oil circuit between engine block and turbocharger unit

Case study: ContiteCh41


from the actuators on the axle to the main valve manifold. In addition, ContiTech supplies refrigerant, as well as charge air hoses and lines, hydraulic engine mounts, and a lightweight torque rod support, multiple V-ribbed belts, and diaphragms for the fuel system, plus automotive interior materials from Benecke-Kaliko.

Smaller and lighter, but at the same time with higher torque

and greater fuel efficiency – these are the additional

requirements that car developers have for modern diesel engines. With this new kind of hybrid hose, ContiTech Fluid Technology has

developed the ideal solution to master the

challenges charge air and cooling water hoses will

encounter in the future. For the upcoming generations of

highly supercharged engines, flexible hoses capable of withstanding a positive pressure of over 3 bar (approximately 43.5psi) will be needed. This flexibility, as well as high pressure and temperature

resistance to the different media flowing through them, are essential for pressure hoses. Therefore ContiTech MGW has developed a flexible hose that satisfies all these requirements and enables a combination of different knitted and rubber materials to accommodate different temperature levels. “The hybrid hose combines extruded- and knitted-hose manufacturing processes with those for wrapped hoses,” notes developer Robert Dill.

New knitted hoses from ContiTech Hose have also entered into series production of the new four-cylinder engine at Mercedes-Benz. They are made using a new knit setting designed for high pressure and dynamic stressing, and are constructed for pressure loads of 3.2 bar. Curved charge air hoses made with the new technology are

intended for a positive pressure of over 3.5 bar. For

a special application, the hose has already been tested with a positive pressure of 4 bar.

For turbocharger lubrication, ContiTech

engineers have has developed corrugated stainless-steel pipes for the high temperature levels in that specific application area. The stiff, corrugated stainless-steel pipes can be installed easily, but are flexible enough to absorb thermodynamic movements and vibrations. In addition to this development,

they demonstrate high corrosion and temperature resistance.

In manufacturing rigid tubes for the lubrication of turbochargers, ContiTech relies on robotic technology. The upshot is top quality, utmost purity, extremely low ppm figures, and marked cost advantages. By reducing complexity the company has also reduced the error potential; fewer parts have to be stocked, and the end result is a sturdier product. By means of two moving annular components, the rigid tubes for diesel and gasoline engines allow for tolerance compensation on the mounted engine without the hose piece common in the past, which also cuts costs. The tubes are currently being used by BMW, Ford, PSA, and Volvo. Solutions for other customers and engines are in the pipeline.

For turbocharger cooling, lines were also developed in which aluminum pipes are joined with a hose section without the need for soldering, thus making the process cost-efficient. The lines can be manufactured in highly automated production, making them competitive with products from countries such as China.

By continuously developing new sustainable products, ContiTech, as a leading rubber specialist, is making a key contribution to the future for a mobile and environmentally conscious society. ETi

above: Cost and weight of transmission oil cooler lines could be cut nearly in half thanks to Contitech developments

the hybrid hose is manufactured by combining processes and materials from extruded- and knitted-hose production with those from wrapped-hose production

CASE STUDY: GOMECSYS42

Author: Bert de Gooijer, technical director, Gomecsys

■ Dutch engineering company Gomecsys is successfully demonstrating the company’s Generation 2 GoEngine technology in a MercedesC-Class sedan. The demonstrator four-inline clearly shows benefi ts when it comes to variable compression ratio, increased fuel effi ciency at low

loads and enhanced torque and power from low rpm. With a minimum compression ratio of 7:1, the VCR GoEngine realizes 400Nm of torque with peak pressures just above 100 bar.

Such performance characteristics mirror a diesel powertrain with low-end torque, which makes it possible

New GoEngine VCR development


Introducing third-generation GoEngine technology that boasts numerous performance, emissions, and fuel economy benefi ts

to down-speed the engine under all driving conditions. Driving at 100km/h, a reduction of engine rpm by 20% (from 2,200rpm to 1,800rpm) gives a 8% reduction in fuel consumption while ensuring extremely good driving comfort levels.

Furthermore, when driving at 100km/h the engine is still on its maximum compression ratio of 16:1. The combination of VCR with down-speeding gives a 20% reduction in fuel consumption levels.

When comparing the 300bhp four-inline GoEngine with a 3.5-liter V6, fuel and CO

2 reduction

could be as great as 40%. The problem with the four-

inline engine in general is that friction levels are just too high when driving at lower speeds. At 50km/h, about half the fuel energy is used to run the engine, even when the Gomecsys engine

runs at very low speeds. As a result, the only way to

make a big improvement in fuel reduction is to make use of smaller engines. In fact downsizing is the way to go, and VCR

technology boosts the result of downsizing.

While demonstrating the company’s second-generation four-inline

GoEngine, engineers at Gomecsys have been working

hard to improve the technology when it comes to friction levels, durability and NVH, which has

led to the introduction of the third-generation GoEngine technology. The development goals of this project included: reducing total GoEngine friction to under normal engine levels; reducing peak gear load to under 50Nm (durability and light-weight gears); and reducing intermediate gear speed to normal level (friction and NVH). The other aims of the project were to realize a normal engine layout with normal fi ring order and balancing; to realize a 50% fuel reduction compared with existing engines with the same power output; and to realize a 25% production cost reduction

“When comparing the 300bhp four-inline GoEngine with a 3.5-liter V6, fuel and CO2 reduction could be as great as 40%”

The two-inline GoEngine can easily replace four-cylinder engines that produce 200bhp

CASE STUDY: GOMECSYS43


four times the crankshaft speed. Yet with the third-generation engine this problem has been solved by placing the intermediate gear between the eccentric gear and the sun gear.

During the development project, Gomecsys engineers agreed that this was a simple engineering solution that offered many advantages. And with this new position, the intermediate gear not only runs at only 1.5 times the crankshaft speed (instead of four times the crankshaft speed), it also doubles the contact ratio between the satellite gear and the actuation ring gear, all of which leads to far better NVH characteristics. The new position of the intermediate gear also makes it possible to transfer the gear load from the eccentric gear to the sun gear, which in turn reduces the gear load by

50% while further enhancing NVH levels.

When looking at the system, the fi rst reaction of any powertrain engineer around the world will be that the gears of the third generation will never be durable due to the rigorous combustion forces in a high boosted engine. Yet in reality the gear loads are very low. Peak eccentric gear load when running at full load and at 120 bar peak combustion pressure results in only 25Nm. It might be hard to believe, but this outcome is simply realized by placing the eccentric position in-line with the combustion force at the lowest compression ratio position.

In fact, the peak forces under full load on all the gears is only 600N, all of which means that the gears could almost be made from plastic. ETi

DIESEL DEVELOPMENTSuch a reduction of the gear loads makes it possible to use the GoEngine VCR technology for diesel applications. For a diesel engine, the technology needs less variation in the compression ratio (from 18:1 to 12:1), which means the technology can work with a smaller eccentric as seen on gasoline engines (2mm eccentricity instead of 4mm). This reduces gear load by 50% when compared with gasoline specifi cations, which means that the technology can easily use the same gear dimensions with 240 bar peak combustion pressure on a diesel application.

The advantage for diesel applications is reduction of the peak combustion loads at higher engine loads, which makes it possible to reduce the size of engine parts and bearings. Furthermore, the technology enables diesel applications to increase peak torque without increasing peak combustion force, which – as with gasoline applications – makes it possible to down-speed the engine. Another big advantage is the reduction of friction levels as well as factors such as NVH and NOx.

With the introduction of the third-generation GoEngine technology, Gomecsys has introduced a line of engine confi gurations with an actuation system at the front of the engine.

Below: The V4 VCR GoEngine can easily replace V6 and V8 engines that produce over 600bhp

Above: The three-inline GoEngine can easily replace powertrains developing up to 300bhp

compared with existing engines with the same power output.

With the introduction of the second-generation GoEngine, a big improvement in friction reduction was realized because the eccentrics that realize the variation in compression ratio run at only half the crankshaft speed. With the eccentric

bearings and the big-end bearings running at half the crankshaft speed, the total engine friction of the second-generation engine was already at the same level as normal engines. A problem was that the intermediate gear ran at

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Case study: a&d teChnology45

Author: Craig Giraud, A&D Technology

A new systems solution that automates calibration through an innovative interface promises many advantages

n The reality facing many OEMs today is how to keep innovating while reducing development time. Adding to that challenge are smaller budgets and fewer resources. Those involved in the engine development process face increasing pressure to provide engines that meet tougher government-mandated emissions regulations, as well as increased customer expectations for durability, performance, and fuel efficiency. The engine mapping and base calibration tasks necessary to help meet

Innovative combustion analysis


abandon the task entirely or submit to having the original equipment supplier do the implementation, usually at a higher cost and with less than best-in-class equipment.

A&D Technology offers a clever solution that provides combustion analysis and automated calibration through an ASAP3 interface, which is the most common protocol used in existing facilities. Combustion analysis is performed via A&D’s CAS, and the automated calibration environment is run through A&D’s ORION

software. The high-speed ASAP3 driver is used to integrate these new tools with the existing data acquisition and control system.

The CAS system provides real-time combustion analysis on up to 16 cylinders, as well as instantaneous feedback for closed-loop control.

Combustion analysis results including power, burn rates, maximum pressures, and knock are transmitted to the test cell automation system and ORION mapping software in order to monitor the progress of the optimization experiment.

these requirements have traditionally consumed many months of a platform development schedule.

Faced with an increasing backlog of test schedules, OEMs are forced to either install new testbeds or add automation to their existing facilities. However, upgrading an engine test bed to full automation represents a major investment, and navigating the plethora of available communications interfaces and equipment can be a daunting task. In the end, most engine developers either

a&d is making engine development easier with new and innovative technologies

46

The ORION automated calibration environment is a supervisory testbed control system for automating the characterization and calibration of engines. ORION provides flexible test automation through user-defined test sequences, as well as an expandable function library. The open interfaces support a wide variety of DoE (design of experiment) and calibration tools.

The ASAP3 connection is a logical choice because of its universal compatibility with data acquisition and control and ECU development systems. The availability of recognized standards such as ASAP3 helps powertrain engineers to enhance project operations and preserve their original investment in testbed systems.

clients on the same PC, a feature that was used to run the combustion analysis system and the ECU development tool.

Server configuration is a simple task of selecting the parameters required by each client by way of drop-down menus. A&D Technology equipment accesses an automatically generated database of parameter names when setting up the data links. Most third-party equipment can be set up by importing an Excel file containing parameter names.

Combustion data from the CAS system is sent via ASAP3 to the data acquisition and control system, which combines the CAS data with ECU parameters and data from other testbed equipment (the data path through the data acquisition and control system is required to align all data from the unit under test). This combined data is transmitted to ORION over a separate ASAP3 link.

Orion then compares the combined data sets with experimental inputs and adjusts ECU parameters by using its own ASAP3 link directly to the ECU development system.

The mapping process typically requires several months of repetitive testing to accurately determine an engine’s optimum operating calibration. However, with a low-cost, straightforward way to integrate combustion analysis and automated calibration capabilities into a data acquisition system, it becomes possible to effectively reduce the time required for development and localization projects by a matter of months. ETi


Case study: a&d teChnology

A&D Technology’s recommended high-speed server is compatible with most testbed hardware, which makes it very easy to add functionality because almost all systems support the ASAP standard. The high-speed server fits between the software application and the Windows network driver, wrapping application data into the ASAP3 protocol. Capable of rates up to 100Hz, the server uses TCP/IP or UDP transmission over Ethernet, improving system performance by avoiding problems with TCP/IP packet resubmissions. Server architecture is compact and efficient, and avoids performance degradation of the original application. It is even possible for the server to support multiple Ethernet

above: oRIon automated calibration technologyleft: Cas data screenshotBelow: asaP3 driver is used to integrate new tools with the existing data acquisition and control system

POWER BEHIND TURBOCHARGED ENGINESTURBO ENERGY LTD.TEL

Case study: aVL48

Author: Beatrice Joerer, AVL

A professional range of e-motor, battery, and hybrid testing solutions uses a model-based approach that integrates simulation, development, and validation to reduce development time and overhead costs

n The successful development of hybrid vehicle concepts requires the introduction of new calibration and testing methods and tools especially for the electric systems such as electric motors, power modules and converters with corresponding control units. With respect to reduced development time and increased product reliability, the performance of test runs based on a fully functional virtual hybrid vehicle – together with simulation of the human driver, the track and the surrounding traffic – is beneficial. AVL List provides electric motor testbeds for developing, optimizing, and validating electric motors as well as power electronic systems.

Electric motor testbed


Common to all hybrid-electric vehicles (HEV) today is the requirement to develop the electric components with respect to different targets in the validation phase of the development process. This includes: experimental measurement and analysis of physical states with respect to the specification, such as the measurement of performance parameters or efficiency maps; loading of the physical components and analysis of the observed effects with respect to the required durability, such as electrical or mechanical stress tests; and optimal calibration of the electronic control units for the electric components, with

respect to the many required functions, including calibration for performance and drivability.

All these activities have to be carried out within the given constraints from regulations such as those relating to consumption and emission limits, the characteristics and expectations of the human driver and the specific environment for the hybrid

vehicle such as ambient, road and surrounding traffic.

Specific testbeds have been used for experimental validation of electric motors and their power modules since the early days of electric drives. In such a testbed the unit under test (UUT) and the dynamometer system operating in speed or torque control are key components. Both are connected with an intermediate shaft. The power module of the UUT is connected to a real vehicle battery or an AC/DC converter that simulates the vehicle battery. In addition, a power analyzer device connected to the DC and AC lines of the UUT and the speed and torque signals from the dynamometer system enables precise calculation of the power and efficiency map for the operating range of the electric motor and its power module.

Another task performed on the testbed is operation under stationary or transient loading conditions to determine the mechanical and electrical durability of the UUT. Dedicated devices such as surge testers are used before a test run to perform the resistance measurements and high-voltage isolation tests with a locked rotor, to determine the electrical parameters of the UUT. During a test run the electric, mechanic and thermal characteristics are measured and compared against the specified targets.

aVL’s advanced range of hybrid testing solutions is helping car makers and suppliers to reduce development times and costs

“The e-motor testbed has also been developed to cover testing under the same high speed and torque gradients”

Case study: aVL49


For automotive application the basic testing of the electric components has to be enhanced by a model-based approach to enable very realistic testing conditions compared to the real vehicle. The AVL e-motor testbed is optimized for: testing of the electric components within an integrated design, optimization and validation process; calibration and testing within the complete virtual hybrid vehicle including simulation of the driver, ambient and traffic; calibration and testing within the complete control network of the vehicle, such as the hybrid powertrain CANbus network.

The e-motor testbed has also been developed to cover testing under the same high speed and torque gradients, especially for e-motors acting as starter generators or e-motors mounted in power-split transmissions; testing with the same reproducible highly dynamic behavior of the electric energy storage system as in the vehicle; and testing under the same

reproducible climatic conditions, such as varying cold start or hot conditions.

The electric motor and power module are mounted into a climatic chamber that controls an ambient temperature ranging from -40°C to 302°C. The cooling fluids for the UUT are also conditioned to that temperature range. The power module is connected to the hybrid control unit (CU) from the real vehicle. Other control units, such as those for the internal combustion engine and the transmission (T/M), are set up on the testbed. All control units are networked with the hybrid powertrain CANbus and connected to the corresponding real-time models on the simulation system with analog and digital I/O. The AVL InMotion simulation system is also connected to the dynamometer and battery simulator hardware located outside the climatic chamber.

The performance and dynamics of the battery system strongly influence the design

and optimization of the electric motor and have to be considered carefully during testing of the e-motor. Very often the energy storage system and the powertrain are developed in different locations; it therefore makes sense to replace the battery with a battery simulator for simulating the battery’s state of charge, operating temperature, and operating voltage. For this purpose a fast real-time controller is implemented into a powerful DC supply based on IGBT technology. This is achieved by using the AVL battery simulator.

The automation and calibration system interfaces with the different control units over CAN using XCP, which is a universal measurement and calibration protocol for data stimulation, data acquisition, and calibration access based on ASAM standards. XCP is used to optimize the parameters of real control units mounted on the testbed or of virtual control units implemented on the simulation system.

A permanent magnet synchronous machine (PSM) with low inertia levels acts as mechanical load unit and can achieve speed gradients up to 100,000rpm/sec, all of which is necessary to accurately simulate the higher-order dynamics of the complex hybrid powertrain on the e-motor testbed.

The behavior of the complete virtual hybrid vehicle on the e-motor testbed is simulated with a real-time platform running detailed models of the driver, combustion engine, battery, transmission, suspension, wheels, chassis, track and surrounding traffic. The model block for the e-motor is replaced with a signal interface to the dynamometer and battery simulator on the testbed. In the operator room a three-dimensional visualization of the virtual vehicle driving on the simulated track, together with the display of the cockpit instruments, provide immediate feedback of the current test status. ETiChart illustrates the torque (Nm) and speed (rpm) capability of aVL’s testing systems

aVL new battery simulator technology will help speed up real-world development

aVL’s electric motor system (left) and the company’s battery testing capability (right) testing such systems as batteries has been made easier thanks to aVL’s investment

CASE STUDY: OHIO STATE50


CASE STUDY: OHIO STATE51

Bulletproof


■ The Buckeye Bullet program at Ohio State University is a one-of-a-kind program that utilizes land-speed racing to push clean technology to its limits on the ultimate proving ground: The Bonneville Salt Flats. On September 25, 2009, the Venturi Buckeye Bullet 2 became the fi rst hydrogen fuel cell vehicle to eclipse the 300mph mark, setting an international speed record of

302.877mph* (*pending offi cial FIA certifi cation) in

the fl ying mile. The Buckeye Bullet 2 program included

over two years of initial conceptual design,

followed by three years of testing, development, and racing.

The 15th anniversary of Ohio

State’s involvement in electric racing was reached in 2009. Beginning in 1994 with the Formula Lightning series, OSU campaigned its vehicle, the Smokin’ Buckeye, until 2002. The series was a collegiate open-wheel formula-style race that traveled to major racetracks around the country. Thirty-one lead-acid batteries powered an AC induction traction system capable of racetrack speeds over 120mph. The team could do a pit stop with a full battery change in under 17 seconds. Ohio State dominated the

competition, winning more than 50% of the races entered and every national championship ever awarded. In 2002, the fi nal running of the Smokin’ Buckeye took place.

As the Formula Lightning series was being phased out, the team found themselves with a great deal of electric racing experience, but no venue in which to put it to use. After some brainstorming and discussions with existing program sponsors, the team decided to take electric racing to a whole new level and go for all-out speed. The goal was to break the world record for top speed in an electric vehicle: 248mph. Over two years (2000-2002) the team of undergraduate engineering students designed and built the Buckeye Bullet 1. The vehicle debuted on the Bonneville Salt Flats in October 2002. Over the course of three years of racing at Bonneville and optimization back in the shop in Ohio, the Bullet worked its way up to a top speed of 321mph. October of 2004 saw the top speeds of the Buckeye Bullet 1 and the shattering of the existing records. The new US record was set at 314.958mph. The Buckeye Bullet was retired after its October 2004 runs, but still holds the US land-speed record in the E/III class (electric power, over 1,000kg).

Design of the world’s fastest hydrogenfuel cell electric vehicle: Buckeye Bullet 2Authors: Carrington Bork, Ed Hillstrom, Kevin Ponziani, Ben Sinsheimer, and Giorgio Rizzoni (Ohio State University, USA); Michael Procter (AFCC Automotive, formerly with Ballard Power Systems, Canada), Systec

push clean technology to its limits on the ultimate proving ground: The Bonneville Salt Flats. On September 25, 2009, the Venturi Buckeye Bullet 2 became the fi rst hydrogen fuel cell vehicle to eclipse the 300mph mark, setting an international speed record of

302.877mph* (*pending offi cial FIA certifi cation) in

the fl ying mile. The Buckeye Bullet 2 program included

over two years of initial conceptual design,

followed by three years of testing, development, and racing.

The 15anniversary of Ohio

State’s involvement in electric racing was reached in 2009. Beginning in 1994 with the Formula Lightning series, OSU campaigned its vehicle, the Smokin’ Buckeye, until 2002.

52

Case study: OhiO state

anode and a cathode separated by a polymer electrolyte membrane. Hydrogen is supplied to the anode and oxygen to the cathode. At the anode, the hydrogen gas ionizes, forming electrons and protons. The acid electrolyte carries the proton through the membrane to the cathode. An external electrical circuit carries the electron to the cathode. The open circuit value for a typical cell is about 1V. Similar to batteries, these cells are connected in series to create a high-voltage circuit.

The fuel cells must provide the required DC electricity to the inverter. They must supply electrical current, at an adequate voltage for the inverter to create the proper wave forms to drive the motor at maximum power. In a fuel cell, the relationship between the current draw and the voltage available is defined by the fuel cell’s polarization curve. The polarization curve is dominated by three areas of losses. Activation losses are present at low currents, and are dominated by the reaction kinetics, primarily on the cathode side. The next major area of loss is the ohmic loss region. The ohmic losses are generally proportional to


Following the success of the Buckeye Bullet 1, the team was looking for a new and exciting challenge, and the Buckeye Bullet 2 (BB2) was born. After years of racing with batteries, the team sought to test a new type of power source: fuel cells. The move to fuel cells from batteries depended on a few key pieces, both technological and logistical. Technologically, the fuel cells delivered a flat power profile, meaning the amount of power available at the end of a run was the same as at the beginning, which was not the case with batteries. Thus, when power was most needed, at the end of the run, there was more power available with fuel cells than with batteries. Logistically, fuel cells are still a very proprietary technology, so a major fuel cell sponsor was necessary to make the project a reality. After getting many industry sponsors together, including Ford Motor Company and Ballard Power Systems, the BB2 was designed from 2004-2006, and fabricated in 2007.

In August 2007, it achieved a peak speed of 201mph. Returning in October of 2007, the BB2 achieved a peak speed of 223mph, but still faced many challenges to reach its target of eclipsing 300mph. Between 2007 and 2008 the team focused on increasing the power available from the fuel cells, and returned in August 2008. The vehicle then recorded a timed mile of 286mph, but ran into severe reliability problems due to oxidant pressure control. For the 2009 race season, much effort was put into the pressure control of the fuel cells. With the support of Venturi, the vehicle returned for a final attempt at an FIA record. On September 25, 2009, in the final run, the BB2 became the fastest hydrogen fuel cell vehicle in the world, setting an average speed in the mile of 302.877mph*.

equation 1

InternatIonal racecourse International speed records may be set on any length of course. In recent years at Bonneville, an approximately 11-mile course has been available. The vehicle is timed over the middle mile. The vehicle must eclipse the timed section in opposite directions, within one hour, and the average speed of the two runs will define the record.

The inverter and motor controller was a piece of technology, along with the motor, that was carried over from the Buckeye Bullet 1 program, where the batteries were the limiting factor. The inverter and motor controller was designed and programmed by Saminco Electric Traction Drives. Interestingly, this controller was originally used with the fuel cell system that was provided by Ballard Power Systems, long before being used for land-speed racing.

The basic I/O structure of the motor controller is a torque reference and DC power input, and three-phase AC power output. Internally there are preset torque limits and other calibration adjustments to tune and optimize the power output from the motor. The DC/AC inversion is performed using variable voltage, variable frequency switching. Ultimately, the electrical power is converted to mechanical energy through the induction motor, and is sent to a six-speed transmission and to the ground via special land-speed tires.

A fuel cell is an electrochemical device that converts chemical energy into electricity. The single cell is constructed of an

“In a fuel cell, the relationship between the current draw and the voltage available is defined by the cell’s polarization curve”

The design of a land-speed vehicle requires the optimization of the vehicle powertrain to overcome the loads against the vehicle. The loads of a land-speed vehicle are fairly easy to predict due to the race conditions. Most of the calculations are actually quite simple, but to quickly evaluate the trade-offs of different design proposals requires the use of simulation tools. Simulink was used as the simulation tool to predict total vehicle performance. The following paper shows some of the details involved in the design of the critical systems.

The standard vehicle road load equation (Equation 1, below) can be simplified due to the Bonneville track conditions. The force to overcome grade is negligible because the track only varies a few centimeters over a span of five miles. The vehicle has no accessory loads in the conventional sense. Most days are very calm, and typically racing is paused if winds are greater than 5mph. The wind’s velocity and direction can then safely be ignored and the aerodynamic load simplifies into longitudinal drag.

123

HEADINGCAsE stuDy: OHIO stAtE53

current, and come from the resistance of the cells’ electrolyte to conduction of protons. The final region of loss comes from the concentration losses. This is where the gas concentrations are depleted near the reaction sites, and reaction cannot be sustained.

The power available from a fuel cell is defined by its power curve, which is calculated directly from the polarization curve. Since electrical power is the product of voltage and current, the power can be plotted versus current. From the power curve it is clear that to attain peak power, the fuel cell should be operated at higher current levels near the power peak. Many components that supply the fuel cell were modified to maximize the peak power attainable from the fuel cells. The losses in the fuel cell polarization curve are all subtracted from the open circuit voltage, which is governed by the Nernst equation. The Nernst equation (Equation 2) describes the open circuit cell potential as a function of temperature, and the partial pressure of hydrogen and oxygen. Inspection of the Nernst equation reveals that higher-pressure operation is a key to maximizing voltage, and therefore power.

The hydrogen and oxygen must pass through a conductive gas diffusion electrode to reach

the catalyst where the fuel is oxidized. At high currents, the partial pressure of oxygen at the fuel cell catalyst is limited by the rate of diffusion between the gas delivery channels and the catalyst. The reduced oxygen partial pressure reduces the fuel cell performance. The rate of diffusion, J, is governed by Fick’s law (Equation 3).

The diffusion coefficient can be increased by changing the balance gases in the oxidant supply. In the Buckeye Bullet 2, a mixture of oxygen and helium is used to increase the diffusion coefficient. This increases the delivery rate of oxygen to the

catalyst, where it reacts with protons and electrons to complete the hydrogen oxidation reaction.

As will be shown below, reactant consumption is linearly proportional to current in a fuel cell. The reactants must be made available in sufficient quantities to ensure that the current demand can be supported. Insufficient reactant delivery will result in a loss of power. If the reactant delivery is less than that required to provide enough electrons, then all of the reactant will be consumed almost instantly and the voltage of the fuel cell will drop to zero. In addition, the reactants should be supplied at the highest possible pressure. The following sections detail the calculation of the flow rates, and the pressure control.

In a fuel cell, electrons are stripped from hydrogen

molecules and conducted through an electrical circuit. Theoretically, hydrogen only needs to be supplied to the fuel cell at the rate it is consumed. This is impractical because as hydrogen flows through the stack and is consumed, the hydrogen concentrations will reach zero at the outlet. In reality, the partial pressure and the concentration need to be much higher for the reaction to be efficient. Hydrogen gas must be supplied at higher mass flow rates than the rate it is actually consumed. The unreacted gas exiting the stack is recirculated back to the inlet via a pump. During normal use, water and other contaminates migrate from the cathode across the membrane and accumulate in the fuel loop. The fuel loop must be periodically purged to clear out these contaminates. The wasted hydrogen is

BB2 traveling at 300mph through the timed mile. At this high speed, with the fuel cells operating at

over 500kW, the massive amount of water being generated can be seen exiting the two exhaust

ports on the side (Image courtesy of Ray the Rat)

the Buckeye Bullet 2 team pictured at Bonneville salt Flats, utah, in 2009

Equation 2

Equation 3


accounted for in a hydrogen utilization factor (μ < 1). Typically, only a small percentage of the total fuel is wasted to satisfy purge cycle conditions.

The rate of hydrogen consumption is proportional to the current drawn from the stack. The mass flow rate of hydrogen can be calculated for a given current. In Equation 4 the current is divided by Faraday’s constant (the amount of charge in one mole of electrons), the number of electrons per molecule of hydrogen, and multiplied by molar mass of

hydrogen and the number of cells in series.

Much like the hydrogen system, the amount of oxygen needed for the reaction is proportional to current. Typical fuel cell vehicles are designed to use oxygen that is in the air

outside the vehicle. A compressor is used to pump air to the desired inlet pressure to flow across the cells. Driven by an electric motor or a belt attached to the main motor, the compressor power takes away from the overall tank-to-wheel efficiency. The compressor is the largest parasitic subsystem for fuel cell vehicles. Often close to 20% of the total power produced by the fuel cell is lost to power the compressor. For a land-speed vehicle, a difference of 20% would severely affect the acceleration and top speed. For the BB2, a special air filtration requirement would also be imposed due to the salty conditions of the air at Bonneville, which could lead to stack damage.

The short duty cycle of a Bonneville speed run enabled other non-traditional automotive oxidant supply systems to be considered. An oxidant supply architecture similar to that of the hydrogen would eliminate the largest parasitic loss. Refilling a pressurized gas cylinder between runs enabled gas mixtures other than air to be considered. It was shown previously that higher oxygen concentrations could allow the fuel cells to run more efficiently on pure oxygen compared with the 20.9% concentration oxygen

found in air. Pure oxygen, however, is considered by many to be more dangerous than hydrogen. A mixture of helium and 40% oxygen was chosen to reduce flow rate requirements, while gaining some of the benefits of oxygen enrichment and maintaining a reasonable level of safety. The oxidant loop differs from the hydrogen because it is not recirculated. The oxidant must also be supplied at a ratio λ higher than needed to support the reaction requirements. The oxidant mass flow calculation is expressed in Equation 5.

The oxidant delivery control system consists of two mass flow controllers that regulate the flow of oxidant into the fuel cell cathode. The traction drive controller interprets the driver command for torque and, given the motor speed, computes a total power demand from the fuel cell. This power estimate is converted into an electric current demand using a polarization curve derived from

With the collaboration of Ballard Engineers, Ohio State Students designed and built the Buckeye Bullet 2 to perform a very specific task: to set the land-speed record for hydrogen fuel cell vehicles

Load bank testingA 600kW capable resistive load bank (below left) is used to test the fuel cell system. Switches are used to progressively increase the load taken by the load bank. The load profile is manually switched to mimic the load seen in Bonneville conditions. The plot (below right) shows module A and B current from Bonneville with the test stand current profile overlaid. The test stand simulation of the transient load profile was instrumental to the success of the BB2 in its 2009 race season.

CaSE Study: OhiO StatE54


Equation 4

Equation 5

load testing of the fuel cells. The electric current demand is communicated to the fuel cell controller via a CAN network. The current request is converted into an oxidant mass flow using Equation 5. The required oxidant is directed by the oxidant mass flow controllers.

The supply rate of the gases is one critical aspect of maximizing the fuel cell power; the other critical aspect is maintaining the gases at the highest possible pressure to minimize voltage losses. However, the fuel cell stack does have pressure limits, which, if exceeded, can result in costly damage to internal seals. The pressure limits were exceeded twice in the 2008 race season, leading to a focus on eliminating this problem for 2009.

For simplicity, the BB2 regulates the oxidant pressure using passive internally piloted back-pressure valves. These valves are adjusted to provide the desired operating pressure at peak temperature and load. On the anode side, hydrogen pressure is regulated through a quick-reacting high-flow hydrogen regulator that is referenced to the cathode pressure. The hydrogen regulator tries to maintain a constant anode pressure that is roughly 500mbar above the cathode pressure.

A big pressure control challenge faced by the BB2 is the result of the integration of a manual transmission shifting sequence. This provides a very dynamic change in current draw on each shift. The fuel cells can be operating at over 400A per module, but on each shift the current will momentarily drop to 0. On the cathode side under load, the exiting gases are a mix of the unused oxygen and the product water in liquid and vapor form. When current draw is stopped, the exhaust gases switch from a low-density, water droplet-rich stream, back to a higher-density pure oxidant stream. The passive back-pressure valves cannot maintain a constant pressure with such a drastic change in gas density, and a pressure spike is seen with each shift.

On the hydrogen side, during high current draw there are pressure losses due to the high hydrogen flow rates. When current draw is momentarily cut for a shift, hydrogen is not being consumed, so the pressure losses are removed, and the hydrogen pressure will spike further above the oxidant pressure level.

To allow operation near the pressure limitations of the stack, without exceeding design pressures, pressure relief valves were installed on the oxidant

and hydrogen supply systems. Extensive testing and system modeling was conducted, so that the pressure spikes during shifts remained below the design limits, and operating pressure is maximized when drawing full load.

One of the challenges for a fuel cell system is the removal of heat. A PEM fuel cell stack could theoretically operate above 70% efficiency, but the efficiency level decreases with the increased current density. The Buckeye Bullet 2 pushes the

current density levels to nearly the peak power point of the fuel cell system, which is a region that operates at approximately 50% efficiency. As a result, this means that if there is 500kW of electrical power being produced, then an equal amount of thermal energy must be removed.

The use of a traditional liquid-air radiator was quickly eliminated due to the aerodynamic drag imposed by the large cooling requirements of the fuel cell systems.

The graphic on the left is a typical fuel cell polarization curve, with polarization properties identified by plotting current versus voltage. The graphic on the right shows a typical fuel cell power curve with the power plotted versus the current

The BB2 vehicle layout. The major factors considered when placing the parts in the vehicle were safety and aerodynamics

Case sTudy: OhiO sTaTe55

Fuel cell powerThis plot shows the fuel cell DC power versus time for one of the record runs. Each drop in power corresponds with a gear shift. For a majority of the run, the Ballard Fuel Cell system, originally designed for 250kW, is operating well over 500kW, with no problems.


against the theoretical peak tractive force of the tire and sent through the driveline.

The actual power is sent to the fuel cells, where the theoretical gas flow rates are computed. The cooling controller manages the heat generation in the stack and maintains the optimal temperature. The total power losses in the driveline system are taken out and the force at the wheel is determined. The road loads are considered, and the resulting acceleration is calculated. The shift controller monitors output power and predicts when output power is better in the next gear. The simulation is terminated when the vehicle has traversed the length of the course.

The results of all the simulation, testing, and design are best seen through the plot of the fuel cell power when the vehicle is raced. The fuel cells delivered peak power output of over 540kW to the inverter. Although no certifiable record for this exists, the vehicle is most likely the most powerful PEM fuel cell vehicle ever created – which underlines the importance of this project, both in terms of the goals achieved and the technology that has been developed.

September 25, 2009, was the last day of racing for the FIA event. At approximately 15:30 local time, traveling west the vehicle achieved an average speed in the timed mile of 301.949mph*. Less than one hour later, the vehicle then

The cooling system is set up as a two-loop system, with a heat exchanger removing heat from the primary loop to the secondary loop through a liquid-to-liquid heat exchanger. The primary loop goes through the fuel cells, a pump, and the heat exchanger. It contains deionized water, since it runs through the fuel cells and is in contact with high voltage. The secondary loop contains regular water, and goes through such subsystems as an ice bath, pump and heat exchanger.

Ideally the fuel cells would be held at an operating temperature of 80°C, with an inlet temperature of 65°C, so a delta T across the stack is maintained at 15°C. However, fortunately the desired thermal cycle is very predictable. To maintain this temperature differential, the flow rate of the secondary loop is regulated with a feedback controller.

With the basic properties of each system of the car understood, a simulator was used to evaluate the overall performance levels of the vehicle. The basis of the simulator resembles that of a traditional vehicle when viewed from the driveline to the wheels. Simulation packages such as MATLAB and Simulink provided the computation tools to implement and analyze such models. The simulated driver keeps the throttle floored at all times except during a shift. Based on known engineering models of the motor, the requested power is checked

traveled east and recorded an average speed of 303.795mph*, setting the mile average at 302.877mph*.

With the collaboration of Ballard Engineers, Ohio State Students designed and built the Buckeye Bullet 2 to perform a very specific task: to set the land-speed record for hydrogen fuel cell vehicles. It has a very specific use profile, so the systems of the car were optimized for this purpose. At the conclusion of the five-year program, the Buckeye Bullet 2 became the fastest hydrogen-powered vehicle in the world, including vehicles using hydrogen for combustion. Using fuel cells to drive an electric motor, the vehicle is also the fastest electrically powered vehicle to hold an international FIA* record. The BB2 is also the first hydrogen-powered vehicle, and the first electric traction vehicle to eclipse the 300mph mark under FIA regulations. ETi

*These are unofficial speeds, and do not qualify as records until the vehicle and speeds have been verified by the record sanctioning body. As such, any record is subject to FIA (or ASN) recognition before it may be recognized as an official record.

References: 1. Larminie, J. and Dicks, A., Fuel Cell Systems Explained (second ed), John Wiley and Sons Ltd (2003).Diamond-like carbon (DLC) coatings are among the newest materials, which provide surface function benefit of the end customers in automotive and other applications.

Gas deliveryThe approximately 1kg of gaseous hydrogen is stored at 350 bar (5,000psi) in a single tank. The oxidant is a mixture of 40% oxygen and 60% helium, stored at 230 bar (3,300psi) in two separate tanks. The gases are regulated and delivered to the fuel cells at approximately 2.5 bar (36psi) at the reaction site.

Case study: OhiO state56

“At the conclusion of the program, Buckeye Bullet 2 became the fastest hydrogen-powered vehicle in the world”

BB2 is not only the first hydrogen-powered vehicle, it is also the first electric traction vehicle

to eclipse the 300mph mark under Fia regulations


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ENERGY RECOVERY TO IMPROVE FUEL EFFICIENCY AND REDUCE CO2

Bowman is the world leader in waste heat energy recovery.

We have developed a range of compact high efficiency turbogenerators to generate electric power from the wasted heat of heavy duty diesel engines. (e.g. exhaust gas stream, EGR heat via an ORC system, e-turbo, etc).

Electric turbocompounding - where the electric power produced is returned to the driveline - shows a clear efficiency improvement over mechanical turbocompounding, and is particularly compatible with hybrid powertrains.

Our initial applications are aimed at 6-16litre trucks, plus off-road and generator set applications up to 50 litre. Systems are being demonstrated on both engines and vehicles , and are already in commercial service for base load gensets. Vertical and horizontal configurations are available, compatible with the exhaust aftertreatment technologies required for 2010 and beyond.

We can fully support your engine development programmes. Contact us to learn more.

ENERGY RECOVERY SYSTEMS

Case study: systeC59

A highly innovative technology for producing a new generation of DLC coatings has been developed and introduced to the market

n Over the past 15 years there has been a variety of developments in materials science. New materials have been produced to address changing industrial needs, such as converting solar energy into electrical or enabling F1 engines to spin at 18,000rpm. But the increase in the legislative pressure to protect the environment further has fueled the development and use of the

new materials that meet the criteria and requirements of the 21st century. The IC engine remains one of the biggest contributors to worldwide pollution and for that reason, reduction of quantity and improvements in quality of IC engines’ exhaust gases remains one of the avenues being widely pursued by auto manufacturers.

Diamond-like carbon (DLC) coatings are among the newest

materials, and provide surface functionalities that go beyond the capabilities of bulk material. DLC coatings have enabled the operation of fuel injectors in gasoline and diesel engines, providing necessary protection against wear, scuffing, and other adverse effects of lubricant-lean friction. DLC films have become a de facto standard when friction reduction coupled with outstanding wear resistance is

required. Typical automotive components that benefit from DLC protection are components of the valvetrain, fuel injection systems, transmission, piston pins, connecting rods, and many others.

In the case of diesel engines, improvement in combustion efficiency is directly linked to the rail pressure of the fuel. Higher pressures lead to fuller atomization and more complete

Diamond-like coatings development


systec IMPaX reactors for producing NoveLC coatings

Authors: Val Lieberman and Thorsten Zufrass, Systec SVS Vacuum Coatings

60

CASE STUDY: SYSTEC


combustion of the fuel, which explains a clear trend toward increasing the injection pressure beyond 2,000 bar. Unfortunately, this challenging engineering task pushes the existing DLC coating technology to the limit.

Systec Vacuum Coatings has been researching and developing a radically different family of DLC coatings, with the goal of bringing them to the new performance level. Substantial increase in coating ability to resist wear, scuffi ng, and fretting while maintaining adequate adhesion were identifi ed as the targets. The limiting factor was commercial viability: the new coating should be produced in a reactor of commercial size at acceptable cost.

Following years of research and development efforts, Systec’s technologists succeeded in producing a new generation of DLC coatings, as well as commercial equipment for its production. Aptly named NoveLC, the new coating family capitalizes on two breakthrough developments in thin-fi lm technology: HIPIMS-assisted metal-ion implantation and a-UBM/PACVD processing.

High Power Impulse Magnetron Sputtering (HIPIMS) is a new, innovative process of pulsed sputtering, where the power is input in short, but very intense (up to 8MW) pulses. As a result, sputtered metal becomes ionized, enabling ion implantation to be carried out. This way a very strong, diffusion-like bond between the coating and substrate is formed, leading to high levels of adhesion. Securing high adhesion levels was an important engineering achievement, as high-performance DLC coating demands extraordinarily strong interface with the substrate.

The second major technical innovation embedded in NoveLC is Systec’s proprietary new deposition technique (a-UBM), which is a fusion of a few concurrently running deposition processes. Although advanced, it was tamed to bring it to a production-friendly level. The NoveLC deposition process is fast and has superior repeatability and reproducibility, with yields up to 100%. The deposition temperature does not exceed 200°C, therefore making this process suitable for coating the majority of automotive components and subsystems. The NoveLC process also eliminates the usual problem of DLC coatings related to localized coating delaminating (pinholes). Importantly, the process costs are comparable to competitive technologies, while produced coatings have much better properties. The NoveLC process is carried out in Systec’s commercial coaters IMPAX 1200 with a coating zone of 900mm diameter and height measurement of 900mm.

Three formulations of NoveLC (F1, F2 and F3) cover all application spectrums from the hardest F1 version to softer, more lubricious F3 type.

NoveLC F1 coating boasts superb adhesion even at a thickness of 5µm and hardness of 4,000 HV, and demonstrates outstanding lubricity and wear rates of a few hundred times less than conventional DLC. Unlike competitive coatings, NoveLCs are very smooth with negligible intrinsic roughness, eliminating the need for post-coating polishing operations.

The NoveLC coatings became commercial at the beginning of 2009 and since then have been successfully penetrating the competitive DLC market in

racing, automotive, and other engineering applications. A few racing valvetrains adopted NoveLC F1 as a better-performing alternative to competitive offerings. Among the automotive applications, Systec NoveLC demonstrated superb results for cam follower applications (for example, fi nger followers), producing not only excellent wear protection, but reduced friction level losses as well. Fuel injectors with NoveLC were able to easily withstand even the highest injection pressure. Equally, such components and subsystems as piston rings, piston pins, intake valves, and other NoveLC-coated components of the engine consistently outperformed conventional DLC coatings.

As a leading international automotive supplier in this fi eld, Systec aims to further expand its range of applications for NoveLC coatings to the benefi t of the end customers in automotive and other applications. ETi

Following years of research and development, Systec’s engineers succeeded in producing a new generation of DLC coatings

The table above shows the impressive properties of NoveLC family of diamond-like carbon coatings for automotive applications

Case study: dsM63

Author: Ralf Ponicki, global marketing manager, Akulon products DSM

A new breakthrough innovation is delivering key weight, noise and system cost benefits in oil sump applications

Material matters


“The main decision criteria for the selection of Akulon PA6 are weight, NVH, and system cost reduction opportunities”

n The main trends in the automotive industry include system cost optimization and productivity gains, as well as long-term sustainability and reduced environmental impact. Each is driven either by legal regulations – reduced CO

2

emissions and fuel consumption – or by profit considerations within the automotive business chain. Engineering plastics can play a pivotal role, as these materials are designed to deliver the required performance while meeting the overall industry trends for lighter and greener solutions that are also more cost-effective.

In the past, a key development has been the drive to introduce engineering plastics for the production of oil sump

dsM, Mann+Hummel and Ford have formed a joint feasibility study that aims to further the development of powertrain parts and subsystems

subsystems. These parts can be exposed to top temperatures of 160°C and need to operate over long periods at 110°C to 140°C. At these temperature levels, Akulon PA6 offers the ideal combination of mechanical stiffness, impact resistance, and also chemical resistance.

Cylinder head covers have been designed and produced in Akulon PA6 for a long time now, and the requirements for oil sumps in terms of temperature and media resistance are similar, because both operate in more or less the same environment. However, impact resistance has always been an issue for oil sumps because parts had to be able to withstand several mechanical tests, such as the stone impact test.

It is for this reason that DSM Engineering Plastics decided to combine its material knowledge with the extensive application knowledge of leading automotive components suppliers to develop feasibility studies, tests, and suitable applications in Akulon PA6.

The main decision criteria for the selection of Akulon PA6 are weight, NVH, and system cost reduction opportunities in combination with design freedom versus metal, as well as better heat aging resistance and better welding strength compared with PA66.

The development of new applications such as these requires extensive CAE support as well as highly detailed calculations and analyses.

64

Case study: dsM


First results indicate that the noise level with PA6 oil sumps is comparable to that of sumps from silent steel, when the design is optimized for plastics. With improved designs it could be possible to contain more oil with the PA6 solution than is possible in today’s metal sumps. Moreover, various other additional functions and features may be integrated in the Akulon PA6 modules.

Akulon PA6 resins have been selected by various OEMs and suppliers for a range of applications and feasibility studies for oil sumps and oil pans. Various engine and road tests are ongoing.

Additional productivity gains are possible by using DSM’s Akulon Ultraflow PA6. This high-flow material enables up to 30% lower cycle times in injection molding in combination with an excellent surface appearance. Akulon

Ultraflow K-FHG7 and K-FHG6 deliver a major improvements in such areas as flow ability, and this comes without losing strength.

Moreover, Ultraflow’s better processing characteristics enable the realization of more complex geometries, which leads to reduced cycle times.

These developments will undoubtedly lead to new engine designs, in which the potential of plastics is more fully realized, eventually leading to more parts integration and smaller engines. In the future we may have engines that consist of a metal core, with

tops, bottoms, and peripherals all made out of plastics, leading to weight reductions of up to several kilograms per engine.

In general, weight reduction is in line with DSM Engineering Plastics’ drive for green materials and solutions. In applications such as these, further benefits may be derived from the recent introduction of EcoPaXX, a bio-based, high-performance engineering plastic for high-tech applications, which has been shown to be 100% carbon neutral from cradle to gate. ETithe spiral flow test: standard akulon Pa6 GF compared to the akulon ultraflow

akulon Pa6 resins have been selected by various car makers and suppliers for a range of engine applications

Applying engineering and materials knowledge, DSM Engineering Plastics first undertook complex feasibility studies (stress, NVH issues, and stone impact).

By not just measuring the performance of the oil pan, but also including the aluminum bedding, which carries loads from the transmission system, a feasibility study was completed on the realization of a complete replacement in plastic of the oil pan and the aluminum bedding. This study was then validated in the DSM, Mann+Hummel, and Ford test laboratories. Subsequently all partners worked to create a real part test, which helped them gain further experience in design, prototype tooling, and assembly.

The first prototype parts in Akulon PA6 are based on multipart designs, where the parts are welded together via vibration welding techniques.

“Weight reduction is in line with DSM Engineering Plastics’ drive for green materials and solutions”

We all know that car emissions are not good for the environment. In the near future, automotive manufacturers are measured by CO2 emissions and there will be additional costs if they do not comply with emission legislation.

SKF can now present a complete portfolio of products and services that range from single bearings and seals to complete powertrain solutions that help reduce grams CO2. As an example, for a final drive application we can reduce CO2 emissions by up to 4 grams, compared to existing solutions. We also offer software which can calculate savings using our products and solutions in today’s and future powertrain concepts.

All in all, these SKF solutions can translate into more than 10 grams CO2

less per km.

The Power of Knowledge Engineering

University focUs: imperial college


66

UNIVERSITY FOCUS: IMPERIAL COLLEGE


67

Racing greenA student engineering team at London’s Imperial College is accumulating extensive experience in the design and development of alternative fuel race cars

■ Imperial Racing Green is a fl agship undergraduate teaching project in which students design, build, and race zero-emission motorsport vehicles. In 2008 it involved 103 students and 33 academics from eight departments.

The project began in 2006 as a loose coalition of undergraduate and postgraduate students and a few staff at Imperial College in response to an invitation from Formula Zero – a company set up to popularize hydrogen fuel cell technologies through motorsport – asking universities from around the world to compete in a new zero-emissions international race series involving hydrogen fuel cell-powered go-karts.

By the summer of 2007 the team had managed to secure seed funding from the EnVision project at Imperial College to build a prototype vehicle, IRG01, and pay some students to build the vehicle over the summer. The vehicle was powered by a 1.2kW Ballard Nexa fuel cell system combined with a large (48V, 800A, 1.5kWh) lithium polymer battery system provided by REAP systems and using Kokam cells. Permanent magnet Lemco LEM200 motors were used to power each rear wheel, and the bus voltage was kept to a maximum of 48V with a DC/DC converter regulating the fuel cell to operate in constant power mode – effectively a range extender.

Building a prototype vehicle was an immensely valuable experience and very useful when designing and building the Formula Zero competition vehicle, IRG02. This was particularly true considering the unknown aspects of much of the technology, and it enabled us to identify early what would be the most challenging aspects. The biggest problem was the DC/DC converter, as the device used on IRG01 was designed as a wall-mounted stationary device, which meant it was

Authors: Dr Gregory Offer, Raj Shah, Benjamin Smith, Billy Wu, and Alexander Schey

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which is activated by the control system; and a relief valve, which will purge the hydrogen in the case of over pressurization. There is also an additional manual valve in the system to purge the system of hydrogen when needed.

The fuel cell has its own balance of plant system (air filters, humidifiers, cooling system). The electricity produced in the fuel cell is passed through the step-down DC/DC converter, which converts the fuel cell output voltage of 76V to the kart operating voltage of 48V. The DC/DC output is passed through LC filters to smooth the signal, and is then stored in the two parallel supercapacitor banks until the 48V limit of the capacitors is reached. As the supercapacitor voltage reaches 46V, the fuel cell begins to ramp down until the voltage reaches 48V, after which it goes into standby mode. As the throttle pedal is pushed down, electricity flows from the supercapacitors to the electric motors via the motor controllers.

Power is transmitted to the rear wheels via a chain and sprocket arrangement. The rear axle is split, which means that independent control of the speed or torque of each rear wheel is possible to optimize the vehicle dynamics. Currently a simple active steering program is used, which works by taking the steering angle and multiplying the power input to the outer motor by a gain proportional to the angle. As a result, the outer wheel will spin faster than the inner wheel, hence the kart can corner more quickly. Another advantage of using DC brushed motors is the ease with which regenerative braking can be implemented.

‘formula’-style race car to compete in various static and dynamic events. This has historically been a competition exclusively for ICE-powered cars, but in 2008 a new alternative fuels category – Class 1A – was introduced for the UK event. This built on the freedom in powertrain design permitted by the Formula Hybrid competition in the USA, itself a spin-off FSAE-based series inaugurated in 2007.

Starting in October 2007, Racing Green embarked on a two-year plan to create a vehicle to enter the competition as a design in 2008 and as a complete car in 2009. The design concept for the car, IRG03, was based around a battery-fuel cell hybrid powertrain system.

The final powertrain system involved the creation of a bespoke battery pack designed in-house with help from ABSL, consisting of 432 Kokam lithium-polymer cells providing 7.5kWh at a voltage of c.300V in a custom support structure. Battery management is provided by REAP Systems modular BMS that monitors individual cells and communicates with the vehicle control system via CAN. In series with the pack, and acting as a range extender, is a 4kW air-cooled Pearl hydrogen fuel cell, which is stepped up from c.75V to the battery voltage via a DC/DC converter.

irg02 getting ready to compete at formula Zero

the first-generation fuel cell system for the irg05 (above). the irg02 formula Zero vehicle sits in the garage, waiting for further engineering tweaks (below)

“The kart was fundamentally a fuel cell supercapacitor hybrid with the supercapacitors acting as temporary energy storage for the power from the fuel cell”

Regenerative braking allows kinetic energy to be recovered by the motors while the kart is decelerating. This recovered kinetic energy is then stored in the supercapacitors ready for the next acceleration event.

Having built a successful entrant for the Formula Zero competition in 2008 and 2009, Racing Green turned its attention to another challenge. The well-known Formula Student UK (FS) competition, which started life as the Formula SAE (FSAE) event in the USA and has since spread around the world, challenges universities to produce a small

69

always unreliable. We knew looking for the right DC/DC converter for IRG02 should be top of the list.

The main powertrain components for IRG02 consisted of a Hydrogenics HyPM 8.5kW fuel cell power module (FCPM), a step-down DC/DC converter, two Maxwell 165F 48V supercapacitor banks, two motor controllers and two DC brushed motors. The kart can fundamentally be described as a fuel cell supercapacitor hybrid, so the supercapacitors act as a temporary energy storage medium for power from the fuel cell.

Hydrogen is stored on board the kart in a pressurized cylinder, and is transported through a hydrogen feed system to the fuel cell. The feed system contains a pressure regulator to step down the cylinder pressure to the required operating pressure of the fuel cell. In order to protect the FC from over-pressurization, three valves are in place after the regulator: a manual shut-off valve, which can be closed in the case of an emergency; a solenoid valve,


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Power from the battery is supplied via analog motor controllers to a Perm 120W 11kW permanent magnet synchronous motor for each wheel. The team incorporated the mounting of the motors via water-cooled plates, which form a structural part of the chassis.

All the vehicle systems are controlled through a National Instrument CompactRio PAC, programmed through the use of LabVIEW software. The control system allows individual control of the motors, either through open-loop current control mode, or in closed-loop velocity control mode, taking throttle pedal position and steering position as the driver input, thereby enabling the use of an electronic differential.

Drive to each of the four wheels is transmitted via a motor face-mounted Neugart epicyclic reduction gearbox, through conventional CV joints and half shafts to the hubs. Taking advantage of the motor position, inboard mechanical brakes are mounted directly on the motor shaft, decreasing unsprung mass and reducing the braking torque required. The other mechanical systems are conventional, including unequal-length carbon fiber wishbones, with suspension provided via coil-over dampers activated through a pushrod and rocker arrangement.

Ultimately the complexity of the vehicle was its downfall, with time running out to prove the vehicle adequately before the race. Although there was the disappointment of being unable to compete in the dynamic events of the 2009 FS UK competition, the team was

rewarded with the award for the ‘most innovative/effective design’.

The team has also worked hard over the summer to get the car running as a testbed for future development, and a number of very important of lessons from the IRG03 exercise have been learned. A battery-heavy hybrid with FC range extender is not the best solution for a track vehicle. The small range required in the 30- minute endurance event of the competition does not merit the extra complexity that the fuel cell brings, despite having a system volumetric energy density (including FC, hydrogen cylinders, and control system) of about 20% that of the battery pack, and a gravimetric energy density of about 50%. This configuration is suitable for a road vehicle, but there are two better solutions for a track car: either fully electric, or a fuel cell supercapacitor hybrid.

The former will be used for IRG03’s successor, IRG04, which will enter Formula Student in 2010/11. IRG04 will use a reconfigured IRG03 battery pack to integrate further safety control systems, and will act as the sole power source on the car. The vehicle concept emphasizes simplicity, and will strive to minimize the number and complexity of the car’s

“The design concept for the IRG03, in keeping with the Racing Green ethos, was based around a battery-fuel cell hybrid powertrain”

Early development of the IRG03, with the team focusing on chassis optimization

IRG03 at Formula Student, summer 2009

systems in order to focus on producing a reliable vehicle that concentrates on maximizing performance as a race car. It will also produce a good mechanical base from which to evolve future vehicles and return to the proven fuel cell supercapacitor hybrid powertrain configuration used in IRG02. This allows the fuel cell to run at its optimum efficiency point continuously, while the supercapacitors allow the rapid power delivery to provide the rapid acceleration required for racing, and robust acceptance of regenerative braking energy.

IRG05, with a further developed powertrain, will be the fifth vehicle to be produced by the Imperial Racing Green project. It will feature two 8kW fuel cell stacks provided by Johnson Matthey and Nedstack, which will be hybridized with a large supercapacitor bank. The balance of plant (BoP) for the fuel cell system is currently being designed and built by the undergraduate students, and is broken down into three main areas: the air systems, hydrogen systems, and cooling systems. The completed system will provide roughly 12kW of net power. Over the last academic year a team of nine students designed and built the first-generation prototype ‘in-house’

unIvERSIty FocuS: ImpERIal collEGE71


fuel cell system in eight months, and tested it successfully with an end-of-life stack.

The current air system features an Eaton M24 Roots-type turbocharger, which is powered by a 48V LEM-200-127 Lynch electric DC motor capable of up to 11kW. This is controlled with the use of a 4QD 300 motor controller for an operating speed of approximately 7,000rpm. The complex inlet manifold for the compressor was designed in the university and then outsourced to be laser sintered.

For the air side humidifi cation, a Perma Pure FC-400-10 unit was used. This recycles the humid cathode exhaust gas at an operating temperature of around 65°C. The hydrogen system has been designed with a recirculation loop to improve hydrogen fuel economy with a Thomas diaphragm pump. A custom-made water separator unit has also been designed and manufactured with the dual purpose of heat exchange and anode side humidifi cation. After FEA validation, this was constructed from polycarbonate and plastic, welded in order to ensure the unit could handle the operating pressures. A solenoid value controlled by a duty cycle PWM provides a means to purge inert gases that cross over the cell membranes from the cathode side of the stack, to improve cell performance.

The cooling system uses a 24V DC Ametek fan mounted on a Honda Civic V radiator with a Jabsco centrifugal high-pressure cyclone pump. The pump is controlled with a SyRen 25A regenerative motor controller on a deionized water loop to maintain an operating temperature of 65°C.

The control of the BoP components is achieved with a CompactRio (cRio) control unit using a LabVIEW-based program. The full fuel cell system has so far been successfully tested up to 3kW.

Some early problems were encountered with the startup of the stack and getting the coolant fl uid up to the operating temperature. Future development work includes replacing the compressor with a low-pressure air blower to reduce parasitic losses, reducing the weight of the rest of the system so as to make it more race focused, and looking at whether a heat pump could be used for FC cooling, and the optimization of end plates.

In a spin-off project from Racing Green, a team of 10 students have volunteered to

design, build and race a plug-in EV supercar capable of navigating the Pan-American Highway. From the most southerly city on the planet, Ushuaia in Argentina, all the way to Prudhoe Bay on Alaska’s northern coast, Racing Green Endurance will be traveling the world’s longest road, aiming to challenge the public perception of EVs as slow, unattractive, and of limited range.

Radical Sportscars is sponsoring the project by providing a Radical SR8. This provides an impressive foundation for the team to design a new electric powertrain optimized to minimize losses and maximize endurance.

EVO Electric has sponsored two of its AF140 motors that will be custom-wound to operate within their optimum effi ciency band at cruising speed, thus eliminating the need for a gearbox and giving the car a top speed of 124mph. With 650Nm and 70kW from each motor, and despite the car being optimized for long-range cruising, it can still achieve an impressive 0-60mph acceleration time of 6.5 seconds. If the car was set up for racing, however, that could be reduced to under four seconds.

In order to control the motors and achieve the most from using two motors on a split rear axle, the car will incorporate two motor drives from Rinehart Motion Systems. These compact drives can handle up to 100kW each, giving us plenty of power to achieve our top speed and acceleration. The drives will communicate with the central control unit – a National Instruments CompactRio – and this will keep the car stable under wet road conditions by using a torque control electronic differential. The drives will also receive messages from the CANbus in the car, and will

“The vehicle will feature two 8kW fuel cell stacks, which will be hybridized with a large supercapacitor”

reduce power under high-temperature conditions to protect the vehicle from misuse. In addition, the CompactRio can monitor the safety circuits in the car in order to disable motor use in an emergency.

The car runs on a modular pack built from Thunder Sky’s lithium-iron phosphate cells. With each cell delivering 100Ah of capacity, and with 169 cells on the vehicle, the battery pack stores an impressive 55.8kWh of energy – even more than that of the current world leader, the Tesla. With all the cells in the pack strung in series to minimize I2R losses and to match the motor voltages, the car requires a battery management system (BMS) in order to keep all the cells balanced and safe.

RGE has teamed up with Frazer-Nash to build a BMS for the car. It will monitor theoretical range, pre-charge circuits, safety contactors, temperature, and state of charge of the whole pack while communicating with the vehicle to optimize energy use for the various environments and drive cycles the car will undergo.

Losses are further minimized by removing the need for a mechanical diff; two motors on a split rear axle are used instead. On a US FTP Highway cycle, the vehicle should achieve 13kWh/100km from battery to wheel, giving it a range of nearly 248 miles. ETIThe IRG03 Formula Student car under construction in Racing Green’s workshop

UNIVERSITY FOCUS: IMPERIAL COLLEGE


72

Racing Green’s engineering team work on the Racing Green Endurance Radical SR0 (above and below left). Meanwhile, fi nal modifi cations are made to IRG03 (below right)

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Authors: Kristin Czubkowski and Jessica Jones, University of Wisconsin-Madison

A Masters degree in engineering is now within easier reach of internal combustion engine engineers around the world, due to an online program from the University of Wisconsin-Madison

Virtual education

n Back in 2003, Rick Geisheker, a design engineer for Briggs & Stratton in Milwaukee, Wisconsin, didn’t mind driving to the University of Wisconsin-Madison once or twice each year to attend seminars on the engine industry. But when Kevin Hoag, a director of continuing engineering education programs for the College of Engineering, told him about a new opportunity to earn a Masters degree in engineering through his personal computer, he knew the university was onto something.

“For a mid-career engineer who wants to brush up his skill set, you have a choice of many, many seminars in our field,” says Geisheker. “Rather than take an untold number of these courses, here was a chance to

get a degree in a program that would have a lot of structure to it, that would cover not only the basics of engine design, but where engines are headed.”

Four years later, Geisheker became one of 10 graduates of the first class of UW-Madison’s Master of Engineering in Engine Systems (MEES) program. The exclusive program has since graduated 37 students, with an impressive 90% graduation rate. Currently 45 students are enrolled in the program, which maintains small cohorts for an optimal learning environment.

According to Hoag, who was on the curriculum committee and is now an instructor for the MEES program, the idea grew out of a lunch meeting with UW-Madison faculty and

Although most students specialize in these two areas, Hoag says the holistic nature of the program, as well as the evolving engine industry, enables students with entirely different sets of skills to be part of the program. For example, one MEES graduate was a software specialist in engine controls. Improving electronic controls and increasing sustainability, Hoag says, are major areas of advancement for the engine industry and the MEES program incorporates these into its curriculum.

Another important part of the program, Hoag says, is UW-Madison’s Engine Research Center (ERC), the largest research program of its kind in the country. “If you’re going to

industry professionals. The program’s curriculum developed, he says, as companies realized that most of their workers naturally specialized in one of two areas of engine research: mechanical development or thermal science.

“Every company said the same thing: that they can see their engineers kind of falling into one of those areas,” he remembers. “Well then, the next question that comes in is, [if] you’ve got a new engine program where you want a chief engineer to lead designing a new engine from a clean sheet of paper, who do you want to lead that program and what kind of expertise do you want? Well, you want somebody who has both of those backgrounds.”

The MEES program has already proved to be a great success, with

many students around the world gaining engineering qualifications

CaSE STudy: univErSiTy of WiSConSin-MadiSon


74

time that’s convenient to all. “We were probably in closer communication about the coursework than students who are living on campus,” states Geisheker.

Hoag says students often end up discussing real-life applications for their course work, which can range from smaller lawn-and-garden engines to larger engines for boats that require a ladder to reach. Rolf Reitz, former director of the Engine Research Center and a professor in the MEES program, says the real-world experience provides an opportunity for online learning. Although students were able to draw from their work experience in class discussions, designing lessons on the highly technical material for those who had not been in school for many years was a hurdle.

“We had to revise the material quite a bit, and at the same time try not to water it down at all because these are technical courses,” he says. “So that was quite a challenge, and I think we improve it as we go along.”

Still, Pferdehirt says, the increasingly global nature of the engine industry means that the MEES program’s web-based communication is much more of an asset than many people realize. “Being able to work at a distance is a need that they have that we can actually help them with. Students on the program graduate not only with the technical knowledge that they’re

looking for, but with an ability to work in a highly collaborative manner with people who are distributed all across the world, because that’s how we work in the classroom.”

Hoag says the program is becoming more international, with MEES students and graduates hailing from the UK, Dominica and India. “The world’s becoming a smaller place, and the boundaries of Wisconsin can be seen as going worldwide.”

In April 2009, MEES was recognized by the United States Distance Learning Association with the 21st Century Best Practices in Distance Learning award for its student-friendly method and processes.

The award was presented to Dr Sandra Ashford, MEES program director, for advancing the knowledge base in the internal combustion engine field, taking innovative approaches to distance delivery, demonstrating a capacity to rapidly adjust to the evolving nature of the distance learning field, and effectively addressing the needs of a varied group of students.

Ashford notes that all of these requirements are at the foundation of the MEES program. “The vision of the MEES program is to provide the highest quality of graduate engineering education to working professionals, and move the internal combustion engine industry forward.” ETi

offer a whole Masters degree program focused on a particular industry, you need the faculty to teach it,” Hoag explains. “The ERC gave us a base of faculty and expertise that we’d need in order to do a Masters degree. There’s certainly no other university in the US, and not many internationally, that could provide that level of expertise.”

Wayne Pferdehirt, director of distance degree programs for the College of Engineering, adds that the web-based format of the program “really shatters people’s perception of what online learning is. They think of online learning as sitting in front of a computer and watching some video, and in fact that’s what a lot of programs are – but it doesn’t have to be that way, and MEES is not,” he says.

Geisheker also praises the program’s methods. Due to its online nature, he says, nothing in his personal or professional life kept him from class during his time in the program.

“I have an adopted daughter from China, and I was able to travel to China with my wife to get our daughter while I was doing coursework,” he says. “Likewise, my business takes me to Japan about twice per year, and I never missed any classwork because anywhere you can connect to the internet, you can be in the classroom.”

Students can communicate three ways while taking a course. They can discuss what they’re learning in an online discussion forum, schedule conference calls to collaborate on projects, or participate in a weekly web conference that brings students together at a

Rick Geisheker is a 2007 graduate of UW-Madison’s Master of Engineering in Engine Systems (MEES) program

“My business takes me to Japan about twice per year, but I never missed any classwork because anywhere you can connect to the internet, you can be in the classroom”

MEES students gain knowledge through the research done at UW-Madison’s Engine Research Center. Shown here are analysis of a diesel spray jet and gas jet

CaSE StUdy: UnivERSity of WiSConSin-MadiSon


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Author: Mathieu Petiteaux, Sogefi Filter Division

How innovative fi lter designs are helping car makers to reduce critical emissions

Filtration systems

■ Emissions reduction is the latest challenge facing the automotive industry. In 2008, the emissions average of European-produced cars was rated at 150g/km. The new regulations state that emissions must be at the 120g/km level for all vehicles manufactured in 2015, and 95g/km in 2020.

Sogefi Filter Division is a leading developer and manufacturer of fi ltration systems for passenger car and light commercial vehicles, and the company is supporting vehicle manufacturers by the development of innovative technologies and products that help reduce vehicle weight and losses incurred by friction.

Sogefi is also helping OEMs with the adaptation of its products to the growing use of alternative fuels.

Engine oil fi ltration systems are deeply impacted by engine downsizing and the biofuels market, which at present mainly consists of alcohol and biodiesel. OEMs now require lighter systems that are able to resist high oil temperatures of up to 150°C. These systems need to work under conditions of high oil fl ow (up to 75 liters/min) with

Above: A schematic view of the Diesel3tech fi lter element

The origin of specifi c fuel consumption and CO

2

emissions of new direct-injection gasoline engines and diesel vehicles equipped with particulate fi lters is the oil mist and particulates contained in crankcase gases (blow-by) burned by the engines. The creation of deposits on the inlet valves increases surge losses over the vehicle’s life. Vehicle fuel consumption is also adversely affected by an increase in pressure caused by mineral ash deposits derived from the engine oil, despite the use of diesel particulate fi lters (DPFs).

Auto manufacturers use blow-by separators with 80% minimum effi ciency under all engine-speed conditions to prevent these phenomena. However, Sogefi has attained

High effi ciency blow-by system

“Sogefi is also helping OEMs with the adaptation of its products to the growing use of alternative fuels” minimum power loss, as well as

providing a 50,000km change interval to optimize the cost of ownership. Solutions have been found through the development of a new range of plastic fi ltration modules associated with synthetic fi lter media-based fi lter elements. The fi rst Sogefi mass production system will go into production in mid-2010 and will be followed by two other such systems later in the year. The design advantages and process fl exibility of technical plastics result in an average weight saving of 0.5kg per engine and have a measurable impact on vehicle CO

2. The use of a new synthetic

fi lter medium, associated with an optimized pleating process, permits a saving of up to 25% of the fl ow restriction.

How innovative fi lter designs are helping car makers to reduce critical emissions

Engine oil fi ltration

impacted by engine downsizing and the

alcohol and biodiesel. OEMs now require lighter systems that are able to resist high oil temperatures of up to 150°C. These systems need to work under conditions of high oil fl ow (up to 75 liters/min) with

High effi ciency blow-by system

CASE STUDY: SOGEFI FILTER DIVISION


76

this level of performance using pleated multilayers integrated into light plastic modules, as well as crankcase pressure regulation valves.

The common diesel fuel fi lter position on passenger cars and light duty vehicles tends to be either on the engine compartment, fi xed on the chassis, or directly on the engine. To reach severe crash test resistance requirements, steel or aluminum casting fi lter shelters are used with negative weight impact on vehicles. Technical solutions exist to install light plastic diesel fuel fi lters outside the crash areas, saving up to 0.7kg of weight without any negative impacts on safety, maintenance, or performance. A tank-mounted plastic rechargeable fi lter has been developed by Sogefi for PSA Peugeot Citroën vehicles, which has been added to the French car maker’s new 3-liter V6 HDI engine.

An innovative thin fl at fi lter concept has also been developed for small vehicles with positive CO

2 quotation feedback from

OEMs. Complementary investigations and reliability testing has now been completed, and it’s ready for an expected product launch

Engine start, especially in cold conditions, is a key

Diesel3Tech has been validated and will start in mass production after being applied to the 2010 Ford super duty diesel vehicles, powered by the new 6.7-liter V8 common rail Panther engine.

Lifecycle analysis shows that the application of all the solutions proposed by Sogefi could achieve a saving of 2g/km of CO

2 on vehicles produced in

Europe in 2015, corresponding to 7% of the targeted reduction.

Sogefi produces green products (based on lifecycle analysis software) that offer decreases in weight and are built with low waste rechargeable modules, all giving permanent improvements. In addition to this, its ISO 14000-certifi ed production plants are situated in close proximity to automotive manufacturers. ETi

an expected product launch Engine start, especially in

cold conditions, is a key

A light-metallic diesel fuel fi lter with central stick

“To optimize power, a new central stick heater design has been developed and patented by Sogefi . This system’s fi rst mass application is in the all-new Renault Laguna”

moment when it comes to analyzing electrical power management on diesel vehicles. More and more power is required and engineers are defi ning maximum peak current values for each component in order to better control the alternator and battery size and weight. The electrical fuel heating system has been integrated into the diesel fuel fi lter to help prevent wax clogging. To optimize power, a new central stick heater design has been developed and patented by Sogefi . This system’s fi rst mass application is in the all-new Renault Laguna. With a 25% electrical power saving compared to previous generation fi lter designs, this powertrain product surpassed all Renault’s expectations.

Another option for OEMs to decrease emissions output and enhance fuel economy is to further develop alternative fuels based on renewable resources. Rape seed and soy fatty acid methyl ester (FAME)-based biodiesel are now incorporated into commercial diesel fuels that are used throughout Europe and the USA.

For these fuels, specifi c materials and technologies are needed for aging compatibility and fuel injection equipment that gives optimum protection and reliability. Based on four years of R&D laboratory and fi eld test validations, Sogefi is guaranteeing all its diesel fuel fi lters for European B30 compatibility. For US B20 fuel, a new technology called

A tank-fi xed plastic diesel fuel fi lter (left) and a plastic oil fi ltration module (right)

Above: A oil fi ltration cartridge with synthetic fi lter medium

CASE STUDY: SOGEFI FILTER DIVISION


77

CASE STUDY: F-DIESEL78

A leading Chinese supplier offers the global automotive industry high-speed, high-power diesel engine research and development

■ The turbocharger is a high-tech product that must meet stringent requirements that only manufacturers with high R&D capability can achieve. F-Diesel is one of the few turbocharging manufacturers that subjects its turbos to several OE qualifi cation tests. These turbo qualifi cation tests ensure F-Diesel produces a safe and reliable turbo for OE applications.

F-Diesel Power, which is located in China, owns an R&D center where the company is engaged in high-speed, high-power diesel engine research and development. The F-Diesel R&D center offers state-of-the-art engineering services as well as test and instrumentation products throughout China. The company employs a staff

Quality powertrain development in China


Author: Yuehong Yuan, F-DIesel

durability, thermal cycle analysis, thrust bearing capacity, on-engine durability, and compressor and turbine housing containment. Other processes that take place include shaft motion, compressor fatigue, heat soak-back, turbo vibration, compressor and turbine seal, compressor and turbine blade frequencies, rotor inertia, and shaft critical speed.

In order to keep pace with international advanced manufacturing, F-Diesel has imported equipment such as advanced CNC lathes, grinding machines, milling machines and CNC machines. The center also boasts vertical pneumatic autobalancers, turbocharger dynamic balancers, 3D measuring equipment, high-accuracy roundness measuring equipment and contour projectors. Such technology ensures that F-Diesel can provide customers with world-class products.

F-Diesel has a quality control principle, which is embedded in the entire manufacturing process along with the previously mentioned advanced equipment. F-Diesel’s highly trained engineers ensure optimal development and production in terms of quality and quantity. With the production concept of TQC, all production processing is strictly controlled according to the TS16949 standards, andF-Diesel’s engineers make use of TS16949 tools, all of which helps to achieve the best quality.

F-Diesel engineers have mastered numerous state-of-the-art powertrain technologies, including the application of

ternary-fl ow analyzed pneumatic computing in the design of compressor wheel and turbine wheel, which optimizes the blade profi le and its manufacturing artwork. The company also has extensive know-how in the application of mixed-fl ow turbine technology, which increases total turbocharger effi ciency by 3%.

In addition to all this, F-Diesel can offer the industry vast experience in the application of PMSAP computing in the design of turbine wheel, with over-speed blade breaking experiment, measurement of the blade self-oscillation frequency, and measurement of the vibration characteristic of the rotor system – all of which has greatly improved product reliability.

F-Diesel engineers have also mastered technologies such as adjustable nozzle, sequential turbocharging, two-stage turbocharging, ball bearing, titanium fusion casting of high-speed centrifugal impeller, titanium-aluminum alloy of turbine wheel, and ceramics turbine wheels. ETi

of over 1,300 highly skilled R&D specialists who provide a broad range of design, analysis, prototyping, development, and testing processes as well as engine integration and calibration capabilities.

The F-Diesel R&D center has become a nationally recognized leader in the design and development of IC engines and turbo systems, and a major supplier of advanced testing and instrumentation products and services to some of China’s largest powertrain OEMs.

The most stringent research and testing methods are undertaken by F-Diesel engineers at the development center, including such processes as compressor and turbine performance, gas stand cyclic

A high-precision turbocharging test station

F-Diesel’s variable nozzle turbocharger

analysis, thrust bearing capacity,

housing containment. Other

In order to keep pace with

manufacturing, F-Diesel has

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123

BIG END

HYBRIDS FOR THE MASSES

80

BIG END

Honda boldly claimed to have developed the world’s fi rst affordable hybrid vehicle, but the company’s all-new Insight model left us feeling rather unimpressed. From a European perspective, the average fuel economy fi gure of 64mpg can easily be matched by a small, four-pot diesel that’ll be cheaper to buy. But we here at ETI have a global outlook, so for markets such as Japan and North America, the new Insight makes sense – and it can even be considered by Europeans as long as it does not hit the autobahns and motorways too often. What doesn’t make sense, however, is the poor ride and the surprisingly cheap feel to the interior, which are fl aws not usually attributed to the Japanese OEM. Honda is desperately trying to keep pace with Toyota in terms of hybrid development, so there are no great complaints about the IMA setup that sees the electric motor develop 14bhp and 78.5Nm of torque, which combines with a nippy 1.3-liter petrol engine that’s good for 87bhp and 121Nm of torque. The nickel-metal hydride battery has been placed under the trunk to help improve the Insight’s center of gravity. Honda engineers worked hard to reduce the size and weight of the IMA system – and up to 95% of the unit is new. Insight’s E-Motor is only 35.7mm thick (the Civic Hybrid’s motor is 61.5mm thick). Despite the technical leap forward that the Insight represents – and the fact that it’s US$2,000 cheaper than the Prius – there’s little doubt in our minds as to which is the better hybrid product.

TO E OR NOT TO E

BMW is adamant that the Mini E is a tech-demonstrator project that will one day lead to an all-electric BMW Group vehicle. However, having been among the fi rst to drive the prototype, we here at ETI are not so sure. Firstly, BMW has confi rmed production of the two-seater Mini Coupe, due in 2012. Why is this so important? Well, having sampled Mini E – which has only two seats due to the very large Li-ion pack on the rear – for us there’s no doubt that the Mini E is more than just an experimental project. Faster than a Cooper S, BMW’s latest all-electric creation is impressive. Producing 150kW and 220Nm of torque, the electric motor seamlessly powers the Mini E from standstill to 62mph in 8.5 seconds before reaching a capped top speed of 95mph. One of the greatest problems is range, but BMW’s head of alternative drives, Alexander Thorwith, insists that Mini E is good for 155 miles after the full charge time of 4.5 hours. Part of the reason why Mini E has one of the greatest ranges is due to the 35kWh battery that’s made up of 5,088 cells grouped into 48 modules – so no problems there. But the benefi ts realized by the batteries are somewhat nullifi ed when you look at the unit itself: it takes up the best part of the rear of the Mini and weighs 260kg. “It’s the pack that remains the biggest challenge,” admits Thorwith, who attempts to rule out a production version of the Mini E by adding, “We need to bring to market a four-seater electric car and we’re looking at such a BMW Group product by 2015.” Watch this space…

BIG END

In creating the new Prius, it would seem that Toyota developed a car fi rst and a hybrid product second, which is why this third-generation offering from the industry leader in hybrid technology gets the thumbs up from us. As with Honda’s IMA, over 90% of Toyota’s Hybrid Synergy Drive System has been redesigned, helping to create a smaller and more compact system that produces much more power than the outgoing Prius. A high-performance, permanent magnet, synchronous 60kW motor works in perfect tandem with a 1.8-liter Atkinson cycle petrol unit that replaced the 1.5-liter engine in the outgoing Prius. The result is an increase in power of 27%, and torque is up by 23%. Like the E-Motor, the 42kW generator is an AC-synchronous type, and the 202V battery uses proven NiMH technology to enable the new Prius to run in EV mode. CO2 emissions are down 14%, to a class-leading 89g/km, and we got more than 60mpg on our test. All round, an impressive package.

TAKE THREE


Like: Makes perfect sense in markets where there are no diesels Dislike: Exposed on motorways

Like: Probably the best hybrid product so farDislike: Some diesels are still more economical

Like: Zero emissions and very good performanceDislike: Battery pack takes up the space of the rear seats

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Engine International Showcase 2009