Engine Optimization Methodologies: Tools and Strategies for Diesel Engine Design

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Engine Optimization Methodologies:

Tools and Strategies for

Diesel 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 ENGINE

FUNDAMENTALS ENGINE TUNING INVERSE DESIGN CVT, INJECTION TIMINGS MAP SHAPING AND MATCHING ENGINE FLEXIBILITY: COMPRESSION RATIO, CVT,HYBRID NOVEL TECHNOLOGIES

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Motivation

• Federal Regulations

–

Fuel economy (CAFE)

–

Emissions (NOx, smog, and other pollutants)

• Public Awareness

–

‘Green’ movement

–

Global warming scare

• Decrease Dependence on Foreign Oil

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Objectives

• Develop an engine optimization framework

–

21

st

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

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Euro III Steady State Test Procedure

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Power Demands on Engine

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HEV System Simulation Framework

ADVISOR Matlab-SIMULINK environment

Parallel HEV

ENGINE FUEL DELIVERY LOOK-UP TABLE

RPM TORQUE

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Baseline 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

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Baseline Cummins Engine Map

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Driving Cycles Investigated

US06 REP05

FHDS FUDS

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Engine Use Points for Various Cycles

US06 REP05

FHDS FUDS

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Power Frequency for Each Cycle

US06 REP05

FHDS FUDS

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Output Torque

Engine Speed

Ideal BSFC Line Generation

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• Determine cumulative fuel throughput for

each cycle investigated

–

Interpolate BSFC from engine map for every

torque/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 Designs

Actual Transmission Case

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Ideal BSFC

vs

. Power Level

Power

BSFC (g/kW-hr)

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Benefits of Flexible Engine Designs

Ideal Transmission Case

• Find ideal BSFC transmission line on engine

map used for a given cycle

–

Interpolate BSFC for every visited power level on

the BSFC vs. Power graph

–

Sum of all BSFC’s is cumulative fuel throughput

–

Mean effective BSFC = numerical average of total

fuel throughput during time steps when engine is

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Potential Benefits of Ideal CVT Design

0 20 40 60 80 100 120 140

US06 REP05 FUDS FHDS

4*BSFCmin 2*BSFCmin

Incr

eas

e in M

ean BSFC Per

Cyc

le

Incr

eas

e in M

ean BSFC Per

Cyc

le

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Optimum Injection Timing Method

• Using an optimization framework

–

Vary injection timing for every torque/speed

combination (over 200 map points, ~100 executions

per point)

–

Computationally prohibitive

• Parallel computer framework

–

Run as many maps as you want at different

injection timings

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Injection Timing Maps

Engine Speed

Output Torque

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Optimum Injection Timing Map

Timing

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Variable Compression Ratio Engine

• Hypothetical investigation of novel engine

design

–

Find the ideal fuel consumption benefit

–

Apply ideal transmission techniques from previous

slides

• Determine how BSFC can be optimized at

various power levels

–

First maximize power density to find engine’s

power upper bound

–

Allow engine controller to change parameters that

are not normally variable

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Problem 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:

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VCRE - Combined Map

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

/k

W

-hr)

vcre_bsfc base_bsfc

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Hybrid Powertrain Investigations

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Demands on Engine - CVT vs. 5-Speed

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Demands on Motor - CVT vs. 5-Speed

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Battery SOC - CVT vs. 5-Speed

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Zero Delta SOC - CVT vs. 5-Speed

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Additional Hybrid Clustering Scenarios

Power-Assist Battery Recharge 40 20 60

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Future Directions

• How realistic is the variable compression ratio

engine for the driving cycles and vehicles we are

considering?

• How can we better quantify the benefits of

increased flexibility in transmission parameters?

• What are the effects of injection timing and

variable valve timing on engine map

characteristics?

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Integration with Target Cascading

• Parameterize engine torque curve

• Maximize engine turndown ratio while

meeting mobility constraints

• Match maximum torque curve with a real

engine defined by high fidelity model

• Use engine visitation points in conjunction

with control strategies to meet BSFC and

emissions targets

• Send results back to top level for verification

and subsequent iteration

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Parameterized Max Torque Curve - I

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Parameterized Max Torque Curve - II

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Sample Torque Curves

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Engine

Matching

Subproblem

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Conclusions

• High fidelity engine model can be used at

different levels in the design process

• Methods have been illustrated on a variety of

different engines

• Continue feed-backward work with ADVISOR

and extend methodology to VESIM