VOLKSWAGEN BLUEMOTION TECHNOLOGIES

ABSTRACT

Human activities are affecting the environment much more and so that every automation company is busy to make its products and projects very efficient and involving many important steps to achieve this target. And Blue motion Technology is one of them that is used by Volks Wagen group of industries and it tries to decrease the impact of human activity on the environment. Blue motion Technology based cars are known as most cleanest cars and very much Eco-friendly in the world. [More...] Volkswagen group of industry is not depending on the old or space age technology. They are making the car engines more efficient by including the electronic circuitry and by modifying some basic cycle parts of the car engine. By using blue motion technology the car engine gets various useful features like TDI, TSI, DSG, automatic start/stop, Recuperation, usage of taller gear ratios, better aerodynamics etc.The products made by using both blue motion technology and electronic circuitry, are very much efficient and reliable rather than other products.

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1. INTRODUCTION

Today the world is become more and more polluted with harmful gases and pollutants like NOx, SOx, HC,

CO2, CO... to name a few. The main cause of the atmospheric pollution is our very own automobiles which now

have become an integral part of our lives. At this moment replacing all the automobiles with some other

alternative is simply not feasible. Due to the increasing pressure from the government and other NGO’s the

automobile manufacturers are feeling the pressure which is motivating them to come with some very good ideas

to make our future greener, cleaner and much more efficient tan it is today.

The adverse affects that atmospheric pollutants have on humans are: Carbon Monoxide (CO) – reduces the

blood’s ability to carry oxygen, aggravates lung and heart disease, and causes headaches, fatigue, and dizziness.

Sulfur Dioxides (SOx) – when combined with water vapor in the air become the major contributor to acid rain.

Nitrogen Oxides (NOx) – cause the yellowish-brown haze over dirty cities, and when combined with oxygen

becomes a poisonous gas that can damage lung tissue. Hydrocarbons (HC) are a group of pollutants that react to

form ozone (O3), some HCs cause cancer and others can irritate mucous membranes. Ozone (O3) is the white

haze or smog seen over many cities. Ozone can irritate the respiratory system, decrease lung function, and

aggravate chronic lung diseases (such as asthma). Carbon Dioxide (CO2), although naturally occurring, can

cause problems. In large quantities it allows more sunlight to enter the atmosphere than can escape – trapping

excess heat that can lead to the “greenhouse effect” and cause global warming.

The first idea was to use a hybrid system; generally an electric hybrid is preferred over other kinds of hybrid

due to its feasibility in the compact dimensions of a car. But there is a problem with hybrid electric vehicle

(HEV). The weakest links are the batteries which stores the electric energy to be used by the electric motor.

They are naturally heavy and quick acceleration and deceleration can severely affect the life of the batteries

moreover the mining of nickel is a highly polluting process. This is why VolksWagen, which is one of the

biggest automakers of the world, has preferred to go without hybrid systems. The strategy of VolksWagen is to

take the conventional internal combustion engine and make them as efficient as it’s possible so that the

environmental impact of these cars will be greatly reduced.

BlueMotion is a trade name (developed externally by UK's Origin Brand Consultants) for fuel-efficient

automobile models from the Volkswagen Group. Volkswagen introduced the name in 2006 on the Mk4 Polo

BlueMotion, and in 2007 a version based on the current Passat was released. More recently, the technology has

been used in SEAT's models like the SEAT Ibiza or the SEAT León under the name Ecomotive, and in the

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Škoda Fabia and Superb, where the technology is called Greenline. BlueMotion versions of the Golf and Touran

were released in 2008. The name refers to VW's corporate colour, blue, and echoes DaimlerChrysler's BlueTec.

BlueMotion Volkswagens use existing technology to improve on the standard engine/vehicle. Currently,

Volkswagen Group focuses in three areas of improvement:

ENGINE:

Revised engine mapping, and including diesel particulate filters help the fuel consumption and

lower NOx levels.

TRANSMISSION:

On the Polo, Golf and Passat the last two gear ratios are longer than on standard Turbocharged

Direct Injection (TDI) engine gearboxes.

AERODYNAMICS:

On the Polo, Golf and Passat, Volkswagen have lowered the suspension, redesigned the spoilers,

and performed additional enhancements underneath each car - so the air is channeled better giving

less drag which produces better fuel consumption.

Why the name bluemotion? Blue - the Volkswagen colour - symbolises the elements water and air, while

Motion represents a move forwards towards the future. BlueMotion Technologies have one very important aim

that is to reduce the impact of cars on the environment for future generations.

Bluemotion cars are not only cleaner, more efficient cars but also offer greater performance. The result is an

impressive range of refinements and innovations that save fuel and cut CO2 emissions. All the technologies

have been grouped together under the badge of BlueMotion Technologies. So the environmental technologies of

today are meeting the driving challenges of tomorrow. At the heart of BlueMotion Technologies are advanced

TDI & TSI engines and DSG dual-clutch gearbox.

Volkswagen has not only made the car more efficient and eco-friendly but it has made the whole manufacturing

process a lot more cleaner and greener making use of modern highly fuel efficient boilers and furnaces.

Preaparing a life cycle assessment(LCA) is a method of understanding the amount of resources going into a car.

Volkswagen has many years of experience with Life Cycle Assessments for product and process optimisation.

They have even assumed a leading role in implementing and publishing life cycle inventories of complete

vehicles. For instance, in 1996 they were the first car manufacturer in the world to prepare a Life Cycle

Inventory study (for the Golf III) and publish it [Schweimer and Schuckert 1996]. Since then they have drawn

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up Life Cycle Assessments for other cars and also published some of the results [Schweimer 1998; Schweimer

et al. 1999; Schweimer and Levin 2000; Schweimer and Roßberg 2001].

These LCAs primarily describe and identify environmental „hot spots“ in the life cycle of a car. Since then they

have broadened the assessments to include production processes as well as fuel production and recycling

processes [Bossdorf-Zimmer et al. 2005; Krinke et al. 2005b]. Since 2007, they have been usuing

environmental commendations to inform customers and the public about the environmental properties of their

vehicles [Volkswagen AG 2007a, Volkswagen AG 2007b, Volkswagen AG 2008].

Volkswagen is also making long-term investments in further developing and optimising Life Cycle Assessment

methods. Thanks to their intensive research they have succeeded in considerably reducing the workload

involved in preparing Life Cycle Inventories. Their research resulted in the development of the VW slimLCI

interface system [Koffler et al. 2007]: this interface not only significantly cuts the workload involved in

preparing Life Cycle Assessments of complete vehicles by automating the process, but also further improves the

consistency and quality of the LCA models produced. This represents substantial progress, since preparing a

complete LCA for a vehicle involves registering thousands of components, together with any related upstream

supply chains and processes. Fig. 1 shows the variety of parts involved in an entire vehicle taking the Golf V as

an example. All these data has helped Volkswagen to improve the manufacturing process and to reduce the use

of conventional fossil fuels in the manufacturing of its cars. Hence the idea of greener cars doesent only starts at

the car but it starts from the whole process of manufacturing it.

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Fig. 1:

Dismantling study of the Golf V

2. TDI (TURBOCHARGED DIRECT INJECTION)

TDI identifies all the VW advanced diesel engines using direct injection and a turbocharger. TDI engines are

economical and smooth with high levels of torque (pulling power) and good energy efficiency. Fuel needs

oxygen to burn and the engine has to be supplied with huge quantities of air to be effective. This problem is

solved using a bigger engine - or by using a turbocharger - as in the TDI. Driven by the exhaust gases, it

squeezes air more tightly into the cylinders. The air is then cooled (cool air takes up less space than hot air)

and diesel is injected directly into the cylinders at very high pressure through a nozzle. It’s this intensive

mixing of highly atomised fuel with the compressed air that leads to better, more efficient combustion.

Makng the driving experience quiet and refined because effective sound insulation keeps noise to a

minimum, while hydraulic engine mounts ensure smooth, low-vibration running. The great advantage of TDI

engines is that they are very powerful, even at low revs, and economical across the entire speed range. This

efficiency also means that one save on fuel costs and emit less CO2, so helping to minimise his/her

impact on the environment.

2.1 The Technology

The engine uses direct injection, where a fuel injector sprays atomised fuel directly into the main combustion

chamber of each cylinder, rather than the pre-combustion chamber prevalent in older diesels which used indirect 5

injection. The engine is coupled with a turbocharger to increase the amount of air going into the engine

cylinders, and an intercooler to lower the temperature (and therefore increase the density) of the air from the

turbo, thereby increasing the amount of fuel that can be injected and combusted. These, in combination, allow

for greater engine performance (from a more complete combustion process compared to indirect injection),

while also decreasing emissions and providing more torque than its petrol engined counterpart. Similar

technology has been used by other companies but "TDI" refers to these Volkswagen Group engines.

Normally-aspirated engines (those without a turbocharger) made by Volkswagen Group use the label

Suction Diesel Injection (SDI). The reduced material volume of the direct injection diesel engine reduces

heat losses, and thereby increases engine efficiency, at the expense of increased combustion noise. A direct

injection engine is also easier to start when cold, due to more efficient placing and usage of glowplugs.

The PD(Pumpe-Düse) design was a reaction to the development of common rail fuel injection by

competitors - an attempt by Volkswagen Group to create an in-house technology of comparable performance

that would not require any royalties to be paid. While Pumpe-Düse engines had a significantly higher injection

pressure than older engines, they were not a match with the very latest common rail, and weren't able to control

injection timing as precisely (a major factor in improving emissions). New engines appearing in 2009 model

year Volkswagens are using the common-rail technique with piezoelectric injectors.

Fuel: TDI engines, like most diesel engines, can run on petrodiesel or B5, B20, or B99 biodiesel subject to

manufacturers' prior approval. In fuel efficiency, and clean emissions when run on biodiesel or when converted

vegetable oil (which should NOT be used on the later PD engines without prior conversion, since irreparable

damage will result), TDI engines are among the best on the market. This is often overlooked because they

do not drive on petrol. A 2007 Volkswagen Jetta 1.9L TDI with 5-speed manual, for example, achieves 5.2

L/100 km (54 mpg UK or 45 mpg US) on the European combined-cycle test while a DSG automatic reaches 5.9

L/100 km (48 mpg UK or 40 mpg US). Newer TDI engines, with higher injection pressures, are less forgiving

about poor-quality fuel than their 1980s ancestors. VW has recently permitted mixes up to B20, and has

recommended B5 be used in place of 100% petroleum-based diesel because of biodiesel's improved lubricating

properties. No. 2 diesel fuel is recommended since it has a higher cetane number than No. 1 fuel and has

lower viscosity (better ability to flow) than heavier fuel oils. Some owners in North America, where cetane

levels are generally poor (as low as 40), use additives or premium diesel to get cetane numbers closer to

the standard levels found in the European market (at least 51) where the engine is designed.

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Improved cetane reduces emissions while improving performance and may increase fuel economy. New

low-sulfur petroleum-only diesel recipes cause seals to shrink and can cause fuel pump failures in TDI engines;

biodiesel blends are reported to prevent that failure.

2.2 The Turbocharger

To boost power output and torque, VW fitted their TDI engines with exhaust turbochargers featuring

variable turbine geometry. They compress the air required for combustion, letting the engine draw in more air

while its displacement and revs stay the same. A turbocharger is powered by the energy in the exhaust gas. It

has two connected turbines. The turbine wheel in the exhaust stream drives the intake compressor, which sucks

in air through the intake system. The compressed air is cooled by a charge air cooler before entering the

combustion chamber. Because cool air is denser than hot air, more oxygen can be fed into the cylinder boosting

the efficiency of the combustion process.

Overcoming turbo lag: The main disadvantage of a turbocharger is that it needs a certain gas pressure to work

which are only available when engine revs are high enough. To avoid 'turbo lag' - a delay in available power -

the turbocharger needs to be able to control the exhaust pressure at low engine revs.

A variable turbine geometry (VTG) turbocharger does this with a system of mechanical guide vanes. These

vanes move to adjust the cross-section area to maximise the air flow into the exhaust turbine. Thus at lower

speeds, a higher flow can be maintained, increasing the pressure to the compressor and therefore increasing

power output.

2.3 Volkswagen’s Injection Systems

They are one of the leaders in developing advanced efficient diesel engines with lower emissions. Their

innovative engines are progressively meeting the new EU 5 standard, ahead of legislation. Their range of three

to ten-cylinder turbodiesel engines are based on unit injector systems, and common rail injection.

Table 1: Comparison between different VW engines.

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How

injection

works?

The

pressure at

which the

diesel is

injected

into the

cylinder is

the key

factor in

diesel direct injection. The fuel has to mix swiftly with the compressed air in the cylinder. The higher the

pressure, the more finely the diesel is atomised for an intensive mixing of the fuel and air particles. This, in turn,

leads to better and more efficient combustion process. The energy from the fuel is used more effectively and

emissions are reduced. We use various injection stages within one power stroke - referred to as multiple

injections. Depending on the engine design, revs and load, modern diesel engines use a pilot or double pilot

injection and a main injection. Pilot injection achieves smooth combustion, ensuring that the extremely high

pressures necessary for combustion to take place are reached more gradually. This significantly reduces

combustion noise and cuts emissions.

Piezo crystal injectors. To control

the injection process precisely and cut

fuel consumption and emissions

significantly, they use piezo inline

injectors instead of solenoid valves.

They are lighter and respond twice as

fast. This enables the injector valve to

switch five times faster to meter the

fuel and control the injection curve far

more precisely, resulting in a

smoother, quieter and more efficient 8

VW Polo 1.6

TDI

VW Polo 1.6 TDI

BlueMotion Technology

VW Polo 1.4 MPI

DSG

Engine capacity [cm3] 1598 1598 1390

Output [kW] 55 66 63

Gearbox 5-speed manual 5-speed manual 7-speed DSG®

Fuel Diesel Diesel Petrol (Super)

Fuel consumption [l/100 km]

(urban/overland/combined)(5.1/3.6/4.2) (4.6/3.2/3.7) (7.7/4.7/5.8)

Emission class Euro 5 Euro 5 Euro 5

CO2 emissions; combined [g/km] 109 96 135

Maximum speed [km/h] 170 180 177

Acceleration 0-100 km/h [s ] 13.9 11.5 11.9

Kerb weight [kg] 1157 1165 1104

combustion process. A post injection phase is also possible with this type of injector, which helps the exhaust

emissions system to be more efficient and results in lower emissions. Common rail - third-generation diesel

direct injection. Common rail is the latest diesel engine technology and is used in many VW vehicles already.

The common rail system stores the injection pressure in a high-pressure fuel reservoir referred to as the

‘common rail’ as it supplies all the injectors. In this system the generation of pressure and the fuel injection

processes are separate.

Figure 2: Comparison between the TDI and normal diesel engine.

Lines connect all the cylinder injectors to the common rail in parallel, ensuring they all have an uninterrupted

supply of constant pressure. The injection quantity and timing are controlled using solenoid valves.

The advantage of common rail is that fuel can be delivered at higher pressure, giving better mixing with air for

a more efficient and cleaner combustion. This gives higher performance combined with improved fuel

consumption.

The ever-higher injection pressures that make diesel engines cleaner and more efficient than before place big

demands on the common rail system. Their latest generation of diesel engines reaches injection pressures as

high as 1,800 bars. For this reason they make the rail themselves, and they are the first car maker to do so.

2.4 Diesel Particulate Filters (DPF)

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The main problem with diesel engine is the amount of soot emission. This is why diesel particulate filter is an

integral part of any diesel engine. The diesel particulate filter: Legislation is continually driving car

manufacturers to produce cleaner and more environmentally friendly vehicles. Their advanced diesel

engines meet this challenge and are cleaner than ever before. One important factor is their diesel particulate

filters (DPF), which are very effective in cutting particulate emissions, trapping even the finest soot particles

that are produced as the engine burns diesel fuel.

The latest generation of filters operate without additives. This makes them maintenance-free for an

exceptionally long time: an initial inspection is usually carried out only after 150,000 km. The filter's lifespan is

dependent on factors such as fuel quality, driving style, use and oil consumption.

3. TSI (REVOLUTIONARY PETROL ENGINE)

What is TSI? TSI is VW’s pioneering technology for petrol engines. TSI engines are compact, high-powered

and use less fuel. TSI technology blends the best of their TDI diesel and FSI (Direct Injection) engines. One can

enjoy excellent drivability and outstanding fuel economy. Acceleration is instant, whichever gear one is using.

So overtaking is safer and one can power smoothly up hills with no delay. TSI technology is available on an

increasing number of VW’s cars, from Golf to Passat.

As responsible car makers VW wanted to make its petrol engines even cleaner and more efficient, while still

being fun to drive. Their aim was to create engines that used less fuel and produced lower CO2 emissions

without sacrificing power. The solution their engineers came up with was both elegant and ingenious: an

engine that combines petrol direct injection with twincharging – a turbocharger and a supercharger working

together. The TSI engine was born. Volkswagen is the only car manufacturer in the world to offer an engine

with this feature. The effect is to combine the benefits of both petrol and diesel power units: smooth and quiet

on the road, TSI delivers high torque - pulling power - throughout the acceleration range with no turbo lag. The

successful TSI formula combines a number of different elements:

3.1 Smaller Engines

At the heart of TSI is a smaller engine. It's more efficient, as there is less power loss resulting from friction. It's

also lighter, so the engine has less weight to shift in the car. Direct petrol injection with charging. Direct petrol

injection is combined with a turbocharger or with a turbocharger and a supercharger working in tandem.

This enhances the engine's combustion efficiency so the TSI engine power output is much higher than that of

conventional, naturally aspirated engines.

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Hunting down every gram: The 140 PS and 170 PS TSI engines are already lightweight. Even then consistent

efforts were made to reduce the weight of the new TSI even more. Its pistons and valve reliefs were designed as

lightweight castings, and the geometries of the asymmetrical stem and wall thicknesses were also optimized to

handle their loads. That is how weight was trimmed gram for gram. On the cylinder head, whose fundamental

concept is also based on the stronger TSIs, it was possible to reduce weight by about 600 grams with a

structure-optimized design. The Volkswagen engineers also reconfigured the intake port. Based on the large

TSI, it was further developed with the goal of achieving a level of swirl or tumble that would not require charge

movement flaps, as already mentioned. In addition, the new intake port was modified substantially. The

advantage: In broad sections of the engine's operating range, it was possible to achieve quicker and even more

efficient combustion with better fuel economy and a smoother engine characteristic. Valves on the TSI are

actuated by two camshafts also further optimized with inlet-side adjustment. Various modifications enabled

weight savings here too: The camshafts each weigh 304 grams less. Every gram counts. That is why even the

cylinder head cover is 150 grams lighter. Overall, the 90-kW TSI is 14,000 grams, or 14 kilograms, lighter than

a TSI with 125 kW.

3.2 Twincharging

On the TSI 1.4 160PS the engine-driven supercharger operates at lower revs, with the turbocharger - powered

by the exhaust gases - joining in as engine speed rises. The supercharger is powered via a belt drive directly

from the crankshaft. This provides maximum pulling power on demand, even at very low engine speeds. TSI

engines are designed to deliver maximum torque from engine speeds as low as 1500 or 1750 rpm. And that has

the twin benefit of not only increasing your driving pleasure but also cutting fuel consumption.

The turbochargers are compact and therefore weight-optimized in design too. In keeping with the overall

concept, the best dynamics and lowest fuel consumption were top priorities. The very quickly responding

turbocharger and the very narrow intake and exhaust cams, together with intake camshaft adjuster, are also

responsible for making 80 percent of the 200 Newton-meter maximum torque available at a low 1,250 rpm. The

refined flow optimization of the integral exhaust manifold and a very carefully optimized exhaust turbine also

deliver excellent, low-loss charger operation, even at high speeds. The maximum speed of the turbocharger is

220,000 rpm. Integrated directly in the compressor housing of the charger is the electrically-controlled divert-air

valve. Its advantage compared to a pneumatic valve: Its construction is more compact and less complex. In

addition, it produces significantly shorter switching response times, so that the turbocharger always operates

optimally, even with abrupt throttle adjustments. An electrically-controlled divert-air valve was introduced for

the first time on the turbo engine on the current Golf GTI.

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An innovation on the new TSI is its water-flow intercooler, which is positioned right in the intake port. It is part

of a low-temperature circulation loop that is independent of engine cooling. The advantage here: The charge air

system exhibits a lower volume than in conventional approaches that use a front intercooler. Numerically

speaking, it was possible to reduce the volume from about 11.0 to 4.8 liters. This significantly shortens the time

required to reach a charge pressure of 1,800 millibar in the intake port. The results: Improved dynamics due to

minimal delays in filling the combustion chamber to its maximum. And the driver of a Volkswagen equipped

with the 122-PS TSI can experience this dynamic gain.

Latest developments: They never stopped refining their TSI technology. Some of their latest ideas for the 1.4

122 PS include: More ways to save weight. These range from a lightened cylinder head cover and a weight

saving per camshaft to the refined design of the cylinder head itself. A new injector with six fuel bores for

electronic direct injection helps achieve this. The injector jets have been realigned to give more efficient

distribution of the fuel mixture in the combustion chamber.

Supercharger boosts pressure at low end: To increase torque at low engine speeds, engine developers selected a

supercharger that is mechanically-driven by a belt. This charger is based on the Roots principle. A special

feature of the supercharger being used is its internal gearing stage located in front of the synchronization gear

pair, which enables high supercharger boost performance at low engine speeds.

Turbocharger kicks in at the upper end: At higher engine speeds the turbocharger (with wastegate control) kicks

in. The supercharger and turbocharger are arranged in series here. The supercharger is actuated by a magnetic

clutch integrated in a module within the water pump. A control flap ensures that the necessary fresh air is

supplied to the turbocharger or supercharger for the given operating point. In pure turbocharger operation the

control flap is open. The air then takes the route of conventional turbo engines, via the front intercooler and

throttle valve and into the intake port. The maximum charge pressure of the twincharger is approx. 2.5 bar at

1,500 rpm. Only in the lower speed range below 2,400 rpm is the supercharger needed to generate the necessary

charge pressure. The turbocharger is designed for optimal efficiency in the upper performance range, and it also

supplies sufficient charge pressure in the middle speed range.

3.3 Charge-Air Intercooling

The turbocharger has a water-cooled intercooler with a low-temperature circuit independent of the engine

cooling system. As a result we've cut the volume of the charge air system by more than half, allowing a high

charge pressure to build up much more quickly. This gives improved dynamics because it reduces the time it

takes to achieve maximum charge in the combustion chambers.

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The first car in the world to have TSI on board was the Golf GT. The 125 kW / 170 PS power and 240 Newton-

meters of torque on this small brother of the Golf GTI contrast with a low 7.2 liters per 100 kilometers average

fuel consumption. This sporty Golf races to the 100 km/h mark from a standstill in just 7.9 seconds. And at 220

km/h it has reached its top speed. Standard equipment on the Golf GT includes a six-speed transmission, but

available as an option on this Volkswagen too is the technically unique DSG dual clutch transmission.

Meanwhile, the large TSIs paired with DSG are not just reserved for the Golf; the engine and transmission are

available today on the Golf Plus, Golf Variant, Jetta and Touran too. Representing the technical foundation of

the TSI on the new, small TSI with 90 kW, for example is a 1,390 cm 3 displacement four-cylinder engine,

whose dynamics, in the case of the GT, match those of a 2.5-liter naturally aspirated engine.

The TSI already develops its maximum torque at 1,750 rpm, which is then constantly in reserve up to 4,500

rpm. The second TSI is the engine version debuting in 2006 on the Golf, Jetta and Touran with 103 kW / 140

PS. TSI stands for a new type of downsizing: For less displacement, less fuel consumption, lower emissions, yet

more power, more torque and more driving fun. The 140-PS TSI develops 220 Newton-meter torque at a low

1,500 rpm and holds this value constant up to 4,000 rpm. To ensure that driving fun is not spoiled when

refueling, all TSI engines are designed to operate with economical, super 95 ROZ fuel.

3.4 Advanced Injection Technology

Electronic direct injection is marked by a newly developed high-pressure injection valve with six fuel spray

holes. Background: A multi-hole high-pressure injection valve of this type was first used on the large TSI

engines. However, on the small TSI the spray behavior was significantly modified. The fuel mixture is

distributed more efficiently in the combustion chamber thanks to a new design of the six injection jets adapted

to the specific needs of this engine. This enabled ignition timing adjustment, and one result was significantly

lower HC emissions (hydrocarbons). The injector itself is arranged on the intake side between the intake port

and the cylinder head gasket level; the maximum injection pressure is 110 bar.

4. DIRECT SHIFT GEARBOX (DSG)

Their acclaimed Direct Shift Gearbox (DSG) has two clutches with electronically controlled gear selection.

DSG gives: Fast, smooth gear changes; lively handling with unbroken acceleration; Safer driving with the

power to get you out of tricky situations; Improved fuel economy, even compared to a manual gearbox, for

many of their new 7-speed DSG ‘boxes.

4.1 Working

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DSG is a groundbreaking 'two-in-one' concept. Available in 6-speed and 7-speed versions, it's totally unlike a

conventional automatic transmission. Twin electronically controlled shafts manage gear selection, always

anticipating your next shift. When one turn the engine on and select Drive mode, one shaft selects first gear

while the second shaft puts the next gear on 'standby'. As the gearbox changes to second, the second shaft is

engaged and the original shaft reaches third. As you shift upwards the sequence continues in a series of

seamless moves.

Because power is simply switched from one shaft to another, not only are gearshifts silky smooth, but

they are also very fast: each change takes less than four-hundredths of a second. The DSG gearbox gives a

choice of two driving programmes: normal and sport. In sport mode, the DSG leaves it longer to shift up the

gears. And if one wants to take over, he/she can control the DSG manually. Nudge the Tiptronic gearlever

forwards or backwards to change gear, or use the paddle shifts mounted on the steering wheel: left for down,

right for up. Both DSG gearboxes are application-specific. The 6-speed is paired with high torque engines (up

to 350 Nm) while the 7-speed variant is more effective in combination with smaller engines and torque outputs

of up to 250 Nm.

4.2 The Technology:

The 6 speed DSG gearbox is made up of two independent gearbox units. With dual-clutch technology - two

clutches in a common housing - both gearboxes are connected under load to the engine in turn, depending on

the current gear, via two drive shafts. Clutch 1 serves the first gearbox unit with 1st, 3rd, 5th 7th and reverse

gear and clutch 2 the second gearbox unit with 2nd, 4th and 6th gear. An output shaft that applies the torque to

the driven wheels via the differential gear is assigned to each gearbox unit. Thanks to the dual-clutch design

the DSG is more efficient than conventional automatic transmission. This efficiency, together with its low

weight and intelligent control, means that DSG can achieve the same, and in some instances better, fuel

consumption, than a manual gearbox or even lower, depending on the style of driving.

4.3 Mechatronics

Electronics and mechanics in one unit. Clutches and gearbox units are operated hydraulically by the

gearbox mechatronics (a combination of mechanics and electronics) housed in the DSG. The electronic

transmission control unit, sensors and hydraulic control unit form one compact unit.

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The control unit does the thinking for you, using information such as engine speed, road speed, and accelerator

position and driving mode to select the optimum gear and to determine the ideal shift point. The hydraulic

control unit then implements the shift commands in a sequence of precisely co-ordinated actions.

Figure 3. Schematic diagram of a 7 speed DSG gearbox.

Split-second

gear changes:

When one

gear is

engaged,

another gear

is always

preselected.

Within four

hundredths of

a second after

the system

detects a gear

change it

opens one clutch and closes the other. The mechatronics unit ensures that this takes place fast and to a level of

accuracy that would not be possible in a manual transmission. The change of gear is imperceptible to the driver

who is merely conscious of the uninterrupted power.

4.4 DSG 7-Speed Gearbox

The new 7-speed DSG gearbox is a world first. What makes it so innovative is its pair of dry clutches which

have dispensed with the need for the oil bath of conventional ‘wet’ clutches. They have been designed

to improve fuel efficiency and driving agility further. The clutches' dry, organic-bonded friction linings need no

cooling. The gearbox is also very compact and requires less power for the gear selection and clutch servo

system. Ideal for motorway driving. Adopting 7 speeds meant our engineers could lower 1st gear to

improve acceleration from standstill and raise 7th gear to act as an overdrive function, ideal for motorway

driving. This can save fuel, cut emissions, and means the car runs even more quietly.

Table 2: Comparison between different automatic gearboxes

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Automatic Transmissions Torque converter transmission 6-speed DSG 7-speed DSG

Number of gears 6 6 7

Max. torque 320 Nm 350Nm 250Nm

Clutch - Wet Dry

Transmission oil volume 5.8l 6.5l 1.7l

Weight 85Kg 93Kg 77Kg

Consumption advantage baseline -0.3 l/100 km -0.8 l/100 km

Efficiency 83% 85% 91%

Figure 4. Dual

clutch.

The

recently developed dual clutch is one of the most radical developments which helped make the DSG such a

ground breaking innovation. Being a dry clutch its not only better in terms of performance but is much lighter

than its earlier counterpart. Figure 4 shows a cutaway diagram of the dual clutch used in the 7 speed DSG

gearbox. Besides core power train and drivetrain components Volkswagen has also made improvement in other

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peripheral equipments related to the car as explained below. Inorder to make the car better not only in the field

of performance but also helping it become more eco friendly.

5. AUTOMATIC START/STOP

Driving in towns involves a lot of stopping and starting, waiting in queues or at traffic lights. And while

the engine is ticking over, it’s using fuel. VW’s efficient Start/Stop technology, introduced on the Passat

BlueMotion, stops this waste, cutting CO2 emissions and saving fuel. The Start/Stop system means that the

car can virtually stop its engine by itself. It works through the clutch, so when the car come to a standstill,

one has to just select neutral gear, release the clutch and the engine switches off with a Start/Stop

symbol appearing on the dashboard. When he/she wants to move off again he/she has to simply dip the clutch,

the engine restarts and you can select first gear and pull away. The system can easily be deactivated, if one

wishes, by a switch within easy reach.

6. RECUPERATION

When one is trying to save energy while driving it makes sense to recover it where one can. VW uses improved

alternators and batteries in combination with an energy management system, to store kinetic energy that would

normally be lost during slowing down or braking. The un-utilized alternator voltage during slowing down or

braking is used to add extra charge to the battery during this period. This extra battery charge can

then be utilised during acceleration or starting, instead of drawing all the energy from the alternator, thus

placing less of a burden on the engine and reducing fuel consumption. Recuperation is a feature of some of our

BlueMotion cars. Along with it the car is fitted with low rolling resistance tyres. They need less engine power to

move the car forward, saving fuel and helping to cut emissions, while still offering excellent performance.

7. GEAR RATIOS

Manual gearboxes with optimised gear ratios are another way of saving fuel. The longer gear ratios for the

higher gears reduce consumption. The lower engine speed also cuts noise - both for those in the car and those

outside it. Fuel saving also depends on how the car is driven and some BlueMotion models are fitted with a

system that indicates a recommended gear, giving one the opportunity to adjust your driving style for greater

economy. According to the driving situation, the intelligent engine management recommends the most efficient

gear in the multifunction display. An arrow pointing upwards tells you to move up a gear, and an arrow pointing

down recommends a lower gear. If the gear already selected is the best one for the current speed, a dot appears.

8. AERODYNAMICS:17

The smoother the airflow over your car as it goes forward, the less drag there is holding it back and the less

effort is needed to move the car forward. That means better performance and lower fuel consumption. That's

why VW constantly optimises the aerodynamics of the cars they manufacture by:

The body is more steamlined and gaps between panels are narrower.

Headlights and indicators are combined.

Radiator grilles, underbody panels and spoilers are designed to reduce drag.

A very slight change in the drag coefficient of a car can help alter the performance of the car significantly,

especially when travelling at high speeds on the highway most of the power produced by the cars goes on to

overcoming the aerodynamic drag so it becomes essential to optimize the aerodynamic performance of the car

in order to make it efficient at high speeds.the greater the speed the greater will be the affect of aerodynamics

on the cars performance for example the worlds fastest car Bugati Veyron has a 1000bhp engine, out of which

250bhp is enough to propel the car to a speed of 300kmph but for the remaining 100 odd Km/H it requires the

extra 750bhp. A comparison between the coefficients of drag of different Bluemotion cars and the normal cars

shows the improved aerodynamics of these cars. In table 3 there is a comparison between the Cd values of

different car models.

Maruthi 800 Maruthi Alto VW Beetle (new) VW Tiguan VW Passat Bluemotion

VW 1 litter concept

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Figure 5: Comparison between automobile drag coefficients (Cd).

9. CONCLUSION

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With the increase in number of vehicles on road it is becoming much important that we make them cleaner and

greener. All the bluemotion technologies together increase the efficiency of an ordinary diesel engine from

38% to about 43% and of a petrol engine from 32% to 36%.

Figure 5: Trend of CO2

emissions during different years

From the graph above its evident that a little change today can mean a much better tomorrow so these small

changes can help in contributing a lot to the future generation. Proper, timely maintenance is essential to make

the car efficient throughout its life, a VW study suggested that proper timely maintenance of simple things like

tyre pressure, engine oil, etc can help save the fuel and thus reduce the emissions.

REFERENCES

i. Joseph Katz, Allen Plotkin; Low-speed aerodynamics, Cambridge University Press, Edition: 2 – 2001.

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ii. Robert Bosch GmbH, Diesel-engine management, Robert Bosch GmbH, 2003.

iii. Herbert Frank Percy Purday Diesel Engine Design, CRC Press, Edition: 5.

iv. Alec Stokes Manual gearbox design, Society of Automotive Engineers, Edition: 3.

v. http://www.volkswagen.co.uk/technology/bluemotion.

vi. http://www.nas.nasa.gov/About/Education/Racecar.

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