Co-sponsored by TACOM and NAVISTAR Vehicle Integration ...arc.engin.umich.edu/events/archive/annual/conf99/assanis_stein.pdf · Torque converter design-Transmission design: Clutch

Vehicle IntegrationVehicle Integration

Dennis Assanis and Jeffrey Stein

May 25-26, 1999

Fifth Annual ARC Conference

Co-sponsored by TACOM and NAVISTAR

Vehicle IntegrationAutomotive Research Center

arc Project TeamProject Team

¥ Jeff Stein, Professor UM

¥ Dennis Assanis, Professor UM

¥ Zoran Filipi, Research Scientist UM

¥ Loucas Louca, Research Fellow UM

¥ Geoff Rideout, Graduate Student UM

¥ Yongsheng Wang, Visiting Researcher UM

¥ Pranab Das, Engine Technology Manager NAVISTAR

¥ Xinqun Gui, Product Engineer NAVISTAR

¥ Dan Grohnke, Senior Development Engineer NAVISTAR

¥ Steve Gravante, Development Engineer NAVISTAR


arc OutlineOutline

¥ Introduction

¥ Vehicle/Engine SIMulation (VESIM)

¥ Simulation Results- Model Validation

- Component Design

¥ Summary/Conclusions

¥ Future Work


arc MotivationMotivation

¥Integrated Ground Vehicle Simulation:-Critical for concurrent engineering: Vehicledesign for MobilityÈPerformance evaluation of alternative vehicle sub-

systems.

ÈDesign and optimization studies:¥ Driveability

¥ Fuel economy

¥ Emissions

¥ NVH


arc Vehicle/Engine Simulation Vehicle/Engine Simulationto Improve Driveabilityto Improve Driveability

¥ Manage Engine Torque- Engine start

- Low idle

- Tip-in control

- Low/High speed acceleration

- Part load cruise

- Vehicle brake

- Steering control

- Load disturbances

¥ Optimize Shift Quality- Vehicle launch behavior

- Vehicle acceleration

- Up-shift and down-shift

- Coast down

- Climbing hills

¥ Compensate DrivelineSurge & Jerk- Driver comfort

- Driveline protection

- PTO applications

- Specialty applications

¥ Manage Engine/ChassisInteractions- Coordinated traction control

- Transaxle management

- Vehicle brake management

- Compression brake

- Exhaust brake control


arc State-of-the-ArtState-of-the-Art

¥ Models of Engines, Drivelines and Vehicle ÒDynamicsÓ arewidely available.- Not easily integrated

- Inappropriate model complexity

¥ Integrated models of these components are:- Not widely available

- Overly simple component models

- Fixed structure models

- Empirical models

- Steady-state models


arc

ÒNRMM is a computer-based collectionof equations and algorithms designedto predict the steady-state operating

capability of a given vehicle operating in a prescribed terrain.Ó

NATO Reference Mobility ModelNATO Reference Mobility Model

¥Transient effects cannot be evaluated¥Models have fixed structure


arc Key IssuesKey Issues

¥ Definitions of vehicle mobility- Driveability

- Gradeability

- etc.

¥ Flexible integrated software environment.

¥ Variable complexity engine, driveline and vehicle models.

¥ Transient engine system models.

¥ Measurements of complete vehicle response.

¥ Validation of integrated models.


arc Objectives for Vehicle MobilityObjectives for Vehicle Mobility

¥Develop and verify a virtual simulationenvironment.

¥Develop and validate physical-based models ofsystem components (engine/driveline/vehicle).

¥Develop evaluation metrics for driveability.

¥Design and evaluate components.


arc Simulation GoalsSimulation Goals

¥ Predictions of engine-driveline-vehicle interactions underhighly dynamic conditions:- Start from stand still

- Gear shifts

¥ Studies and evaluation of different system configurationsand design options:- Engine fueling strategy, EGR management

- Engine/turbocharger matching

- Torque converter design

- Transmission design: Clutch and gear ratios

- Tire/suspension tuning


arc

IM

InterCooler

Air Exhaust Gas

Trns

D-R

T C

C

EM

T

VEHICLE DYNAMICS

DIESELENGINE

DRIVELINE

Vehicle Systemð IntegrationVehicle Systemð Integration


arc Integration ofIntegration ofVariable Complexity ModelsVariable Complexity Models

t

RPM

MULTI-CYLINDERDIESEL ENGINE

EXHAUSTMANIFOLD

INTAKEMANIFOLD

INTER-COOLER

COMPRESSOR TURBINE

WA

ST

EG

AT

E

FUELSYSTEM

Air

FuelExhaustgas

W.

EMPIRICAL POINT-MASS

THERMODYNAMIC

MULTI-BODY

SIMPLIFIED

HIGH-FIDELITY

VEHICLE DYNAMICSENGINE


arc Non-Linear, TransientNon-Linear, TransientDiesel Engine ModelDiesel Engine Model

CYLINDERCONTROLVOLUME

Convective heat transfer;based on turbulent flow in

pipes

Global turbulencemodel based on the energy

cascade concept

Radiation (duringcombustion); Assanis-Heywood or Annand

Quasi-steady, one-Dflow equations for flow

past the valves

Engine dynamicsAnd Friction

Phenomenologicalcombustion model -

Watson

Ignition delay -Arrhenius

Parent simulation: Assanis and Heywood (1986)


arcExternal Component ModelsExternal Component Models

IM

InterCooler

C

EM

T

ÒFilling and emptyingÓ ofmanifold control volumes

Empirical correlations formanifold heat transfer andpressure loss

Turbomachineryperformance defined

by maps

Turbocharger dynamicscontrolled by rotorinertia and damping

Intercoolerperformance defined

by intercoolereffectiveness


arc

Trns

D-R

T C

Driveline ModelDriveline Model

Flexible Propshaft

Flexible Driveshaft

¥Quasi-Static¥Lookup Tables

¥Flexible Gears¥Gear Inertias¥Gear Ratios¥Blending Functions¥Clutches¥Shift Logic

Wheel Hub

¥Equal Torque¥Gear Inertias


arc Vehicle Dynamics ModelVehicle Dynamics Model

Longitudinal

¥Wheel Inertia¥Wheel Slip¥Rolling Resistance

¥Total Vehicle Mass¥Aerodynamic Drag

Heave

Road ExcitationFlexible Tire

SprungMass

UnsprungMass

Suspension

Coupling


arc VVehicleehicle E Enginengine SIMSIMulationulation

Double Click to Plot Engine

Double Click to load data

Double Click to Plot Powertrain

Double Click to Plot Vehicle

WheelTorque

Brake

Road Profile

WheelSpeed

VEHICLE DYNAMICS

time_fast

time

Road Profile

Driver demand

EngineSpeed

Driver Demand

WheelSpeed

EngineTorque

WheelTorque

DRIVELINE

Load Torque

Driver command

EngineSpeed

DIESEL ENGINE

Clock

Brake Table


arc Vehicle SpecificationsVehicle Specifications

¥ V8 DI Diesel

¥ Turbocharged, Intercooled

¥ 7.3 liters

¥ Bore: 0.1044 m

¥ Stroke: 0.1062 m

¥ Compression Ratio: 17.4

¥ Rated Power: 210 HP@2400 rpm

¥ GVWR: 7950 Kg

¥ Wheelbase: 3.7 m

¥ CG Location: 2.2 m from front

¥ Frontal Area: 5 m2

¥ Air Drag Coefficient (CD): 0.8

¥ 4 Speed Automatic Transmission

¥ Rear Wheel Drive - 4x2

Vehicle/DrivelineEngine

NAVISTAR 4700 Series


arc Case StudiesCase Studies

¥Launch Performance-Validation

-DesignÈFueling strategy

ÈTorque converter

¥Driveability- Shift Quality

ÈClutch design


arc Launch PerformanceLaunch Performance

¥ Vehicle starting from standstill- Engine is idling

- Brakes are applied

¥ Launch vehicle by:- Releasing brakes

- Pressing the gas pedal all the way

¥ Experimental data are obtained:- Engine Speed

- Vehicle Speed

¥ Simulation results are generated under the same conditions


arc Model Validation (0-60 MPH)Model Validation (0-60 MPH)

0 5 10 15 20 25 30 350

500

1000

1500

2000

2500

3000

0 5 10 15 20 25 30 350

10

20

30

40

50

60

Eng

ine

Spe

ed [r

pm]

Time [sec]

TestVESIM

Veh

icle

Spe

ed [m

ph]

Time [sec]

TestVESIM

1st 2nd 3rd 4th Gear


arc

0 1 2 3 4 5 60

500

1000

1500

2000

2500

3000

3500

4000

Model Validation (Stall Test):Model Validation (Stall Test):Engine/Torque Converter InteractionEngine/Torque Converter Interaction

Eng

ine

Spe

ed [r

pm]

Time [sec]

TestVESIM


arc

DriverDemand

Tip-inFunction

Fueling Map

Modified Map: less restrictive correction atlow boost/low speed

Fueling StrategyFueling Strategy

Engine SpeedAnd

Boost Pressure

MinFuel to

Cylinder

BaseCalibration

0.81

1.21.4

1.61.8

x 105

-50

0

50

100

15040

50

60

70

80

90

100

Boost pressure

Fueling map - boost correction

Percent rated speed


arc

-1 0 1 2 3 4 5 60

500

1000

1500

2000

2500

3000

Fuelling Strategy:Fuelling Strategy:

Engine ResponseEngine Response

Standard Fuel MapModified Fuel MapE

ngin

e S

peed

[rpm

]

Time [sec]


arc

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

5

10

15

Standard Fuel MapModified Fuel Map

Veh

icle

Spe

ed [m

ph]

Time [sec]


Vehicle ResponseVehicle Response


arc

0 0.2 0.4 0.6 0.8 1 1.20

0.5

1

1.5

2

2.5

3

3.5

4


Veh

icle

Jer

k [m

/s3 ]

Time [sec]


Vehicle JerkVehicle Jerk


arc

0 1 2 3 4 5 60

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1F

uel t

o A

ir R

atio

Time [sec]



In-Cylinder Mixture CompositionIn-Cylinder Mixture Composition


arc

0 1 2 3 4 5 6 70

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4P

rem

ixed

/Diff

usio

n C

ontr

olle

d B

urni

ng

Time [sec]



Combustion, Premixed Combustion, Premixed vsvs Diffusion Diffusion


arc Torque Converter DesignTorque Converter Design

0 1 2 3 4 5 60

500

1000

1500

2000

2500

3000

3500

4000E

ngin

e S

peed

[rpm

]

Time [sec]

StockAlternate


arc Shift QualityShift Quality

¥Study the effect of shifting on:-Driveability

¥Vary the duration of the shift event:-Nominal design: 0.8 seconds

-New designs:È0.4 seconds

È1.2 seconds


arc Clutch TimingClutch Timing

Speed Ratio

Torque Ratio

Time

Shift Duration


arc Shift Quality - Vehicle JerkShift Quality - Vehicle Jerk

4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6-8

-6

-4

-2

0

2

4

6

8F

orw

ard

Jerk

[m/s

3 ]

Time [sec]

0.4 sec shift0.8 sec shift1.2 sec shift


arc Shift Quality - Wheel SlipShift Quality - Wheel Slip

Decrease in shift duration increases tire wear

Whe

el S

lip

4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6-0.2

-0.18

-0.16

-0.14

-0.12

-0.1

-0.08

-0.06

-0.04

-0.02

0W

heel

Slip

Time [sec]

0.4 sec shift0.8 sec shift1.2 sec shift


arc SummarySummary

¥ Integrated virtual vehicle for mobility studies.

¥ Verification of integrated model response under selectedconditions.

¥ Studied the design of fueling strategy, torque converterselection, shift duration on vehicle mobility.

¥ Demonstrated tradeoffs between driveline and enginedesign.


arc ConclusionsConclusions

¥ Higher fidelity vehicle/engine integration is possible.

¥ Engine/vehicle interactions are important to vehicle mobilitydesign and evaluation.

¥ Additional work on the definitions of mobility, models ofengines and drivelines is necessary.


arc Future StudiesFuture Studies

¥ Measure complete response.

¥ Create a spectrum of component models.

¥ Determine appropriate use of component models.

¥ Define mobility metrics: driveability, gradeability, etc.

Documents

Co-sponsored by TACOM and NAVISTAR Vehicle Integration ...arc.engin.umich.edu/events/archive/annual/conf99/assanis_stein.pdf · Torque converter design-Transmission design: Clutch