Engine Optimization Methodologies: Tools and Strategies for Diesel

Automotive Research Centerarc

Diesel Engine Optimization MethodologiesDiesel Engine Optimization Methodologies

NAC

Engine Optimization Methodologies:Engine Optimization Methodologies:

Tools and Strategies forTools and Strategies forDiesel Engine DesignDiesel Engine Design

George Delagrammatikas

Dennis Assanis, Zoran Filipi, Panos Papalambros,Nestor Michelena

The University of Michigan

May 24, 2000



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BACKGROUND:

VEHICLE AND ENGINEFUNDAMENTALS

ENGINE TUNING

INVERSEDESIGN

TARGETCASCADING

CVT,INJECTIONTIMINGS

MAPSHAPING

ANDMATCHING

ENGINE FLEXIBILITY:COMPRESSION RATIO,

CVT,HYBRID

NOVELTECHNOLOGIES



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MotivationMotivation

• Federal Regulations– Fuel economy (CAFE)

– Emissions (NOx, smog, and other pollutants)

• Public Awareness– ‘Green’ movement

– Global warming scare

• Decrease Dependence on Foreign Oil– Avoid another oil crisis



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ObjectivesObjectives

• Develop an engine optimization framework– 21st century conventional and hybrid heavy truck

• Implement techniques to conventional vehicle– Define a problem analytically

– Apply suitable driving cycle(s)

– Investigate location of use on engine map

• Extend lessons learned to hybrid vehicle– How different are demands on engine and

transmission?

– Need for a systems approach



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Euro III Steady State Test ProcedureEuro III Steady State Test Procedure



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Power Demands on EnginePower Demands on Engine

Torque,Speed

at Wheel

Torque,Speed

at EngineWHEEL ENGINE



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HEV System Simulation FrameworkHEV System Simulation Framework

ADVISOR

Matlab-SIMULINK environment

Parallel HEV

ENGINE FUEL DELIVERYLOOK-UP TABLE

RPMTORQUE

FUEL (g/s)



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Baseline Vehicle ParametersBaseline Vehicle Parameters

Cummins M11-330 (246 kW) Diesel Engine

Wheel/axle assembly for heavy truck

Kenworth T400 Vehicle

Standard heavy vehicle accessory loads

Standard catalyst for CI engine

Eaton Fuller RTLO-12610B 10-Speed Transmission

Generic 10-spd constant efficiency gearbox

Heavy Vehicle Powertrain Control

Eaton Fuller RTLO-12610B 10-Speed Transmission

Generic 10-spd constant efficiency gearbox



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Baseline Cummins Engine MapBaseline Cummins Engine Map



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Driving Cycles InvestigatedDriving Cycles Investigated

US06 REP05

FHDSFUDS



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Engine Use Points for Various CyclesEngine Use Points for Various Cycles

US06 REP05

FHDSFUDS



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Power Frequency for Each CyclePower Frequency for Each Cycle

US06 REP05

FHDSFUDS



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Ou

tpu

t T

orq

ue

Ou

tpu

t T

orq

ue

Engine SpeedEngine Speed

Ideal BSFC Line GenerationIdeal BSFC Line Generation



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• Determine cumulative fuel throughput foreach cycle investigated

– Interpolate BSFC from engine map for everytorque/speed combination for that given cycle

– Integrate all BSFC’s from above step

– Find the total time that engine is producing power

– Mean effective BSFC = total BSFC/engine on time

Benefits of Flexible Engine DesignsBenefits of Flexible Engine DesignsActual Transmission CaseActual Transmission Case



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Ideal BSFC Ideal BSFC vsvs. Power Level. Power Level

PowerPower

BS

FC

(g

/kW

-hr)

BS

FC

(g

/kW

-hr)



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Benefits of Flexible Engine DesignsBenefits of Flexible Engine DesignsIdeal Transmission CaseIdeal Transmission Case

• Find ideal BSFC transmission line on enginemap used for a given cycle

– Interpolate BSFC for every visited power level onthe BSFC vs. Power graph

– Sum of all BSFC’s is cumulative fuel throughput

– Mean effective BSFC = numerical average of totalfuel throughput during time steps when engine isactive



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Potential Benefits of Ideal CVT DesignPotential Benefits of Ideal CVT Design

0

20

40

60

80

100

120

140

US06 REP05 FUDS FHDS

4*BSFCmin

2*BSFCmin

Incr

ease

in M

ean

BS

FC

Per

Cyc

leIn

crea

se in

Mea

n B

SF

C P

er C

ycle



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Optimum Injection Timing MethodOptimum Injection Timing Method

• Using an optimization framework– Vary injection timing for every torque/speed

combination (over 200 map points, ~100 executionsper point)

– Computationally prohibitive

• Parallel computer framework– Run as many maps as you want at different

injection timings

– Coalesce data with a Matlab-based routine

– One map = ~5 minutes



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Injection Timing MapsInjection Timing Maps

Engine SpeedEngine Speed

Ou

tpu

t T

orq

ue

Ou

tpu

t T

orq

ue



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Optimum Injection Timing MapOptimum Injection Timing Map

RPMRPMFuelingFueling

RateRate

Tim

ing

Tim

ing



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Variable Compression Ratio EngineVariable Compression Ratio Engine

• Hypothetical investigation of novel enginedesign

– Find the ideal fuel consumption benefit

– Apply ideal transmission techniques from previousslides

• Determine how BSFC can be optimized atvarious power levels

– First maximize power density to find engine’spower upper bound

– Allow engine controller to change parameters thatare not normally variable



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Problem FormulationProblem Formulation• For each power level :

– 50, 100, 200, 300, 400, 500 kW

• Minimize BSFC, subject to:– overall phi < 0.6

– 20% < percent premixed burn < 40%

– peak cylinder pressure < 150 bar

• Variables:– Inlet manifold pressure

– Compression ratio

– Injection timing

– Fuel

– Engine speed



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Same Engine - Different MapsSame Engine - Different Maps



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VCRE - Combined MapVCRE - Combined Map

RPMRPM

TO

RQ

UE

TO

RQ

UE



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Ideal BSFC Line vs. Power Level

170

180

190

200

210

220

230

240

50 100 150 200 250 300 350 400 450 500

Power (kW)

BS

FC

(g

/kW

-hr)

vcre_bsfc

base_bsfc



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Hybrid Powertrain InvestigationsHybrid Powertrain Investigations



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Demands on Engine - CVT vs. 5-SpeedDemands on Engine - CVT vs. 5-Speed



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Demands on Motor - CVT vs. 5-SpeedDemands on Motor - CVT vs. 5-Speed



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Battery SOC - CVT vs. 5-SpeedBattery SOC - CVT vs. 5-Speed



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Zero Delta SOC - CVT vs. 5-SpeedZero Delta SOC - CVT vs. 5-Speed



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Additional Hybrid Clustering ScenariosAdditional Hybrid Clustering Scenarios

Power-Assist

BatteryRecharge

40

20

60



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Future DirectionsFuture Directions

• How realistic is the variable compression ratioengine for the driving cycles and vehicles we areconsidering?

• How can we better quantify the benefits ofincreased flexibility in transmission parameters?

• What are the effects of injection timing andvariable valve timing on engine mapcharacteristics?

• Is it better to cluster points around optimumpower levels on an engine map or disregard thatan engine can be described by a single map?



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Integration with Target CascadingIntegration with Target Cascading

• Parameterize engine torque curve

• Maximize engine turndown ratio whilemeeting mobility constraints

• Match maximum torque curve with a realengine defined by high fidelity model

• Use engine visitation points in conjunctionwith control strategies to meet BSFC andemissions targets

• Send results back to top level for verificationand subsequent iteration



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Parameterized Max Torque Curve - IParameterized Max Torque Curve - I



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Parameterized Max Torque Curve - IIParameterized Max Torque Curve - II



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Sample Torque CurvesSample Torque Curves

Min cluster area Min rated torque

Min rated power



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EngineEngineMatchingMatching

SubproblemSubproblem



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ConclusionsConclusions

• High fidelity engine model can be used atdifferent levels in the design process

• Methods have been illustrated on a variety ofdifferent engines

• Continue feed-backward work with ADVISORand extend methodology to VESIM

Documents

Engine Optimization Methodologies: Tools and Strategies for Diesel