Modeling and Analysis of a Lean Combustion Engine by ... · Lean Combustion Modeling . Gasoline Systems . 7 Combustion Engine Model for Vehicle Simulation GT Map-based Engine Model

GS/ESC2 - Tophoven | 8/14/2013 | © Robert Bosch GmbH 2013. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Lean Combustion Modeling, GT-Conference 2013

Gasoline Systems

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Modeling and Analysis of a Lean Combustion Engine by Combining Engine and Vehicle Simulation

GS/ESC2 - Jens Tophoven


Lean Combustion Modeling

Gasoline Systems

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Content

1. Standardized Simulation Methodology • Motivation • ICE Model • Vehicle Model • Modifications for SGDI

2. Results of SGDI-Simulation • F/C-Map • Detailed Analysis

3. Summary and Outlook

3

Eng. Disp.

No. of Cyl.

CR

DI/PFI

TC/NA


COD


Gasoline Systems

High Diversification in Powertrain Topologies As a Consequence an Overall System Optimization is required

Engine

Dual Clutch

E-Motor DCT

Clutch 1

> 100V

48V

Engine Clutch

MT

Engine eCS MT

14 V

48V BRS

PHEV - P2 w/ DCT

BRS on transmission side (w/ eCS)

Conventional Powertrain

Boost

e-Drive

Recuperation

Coasting

Powertrain-Topology Engine Configuration Operating Strategy

Hybrid-Drive

Min. CO2

14V

SGDI



Gasoline Systems

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Motivation for Standardized Simulation Methodology Target: Detailed analysis of components and effect on FC and DPI

Buildup of a Standard Engine Model based on a modern Benchmark Engine

Uncertainties for Analysis based on Measured Maps

Engine Friction and Auxiliary-Operation

No Component Switch within same Engine Generation

Tolerances in Lower Heating Value

FC Measurement at very low Load

BM

EP

[bar

]

Engine Speed [RPM]???

no

relia

ble

anal

ysis

po

ssib

le

Simulation based Approach



Gasoline Systems

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Fluid Dynamics

Friction

Combustion

Combustion Engine Model Developing a State-of-the-Art Engine Model

Benchmark Engine

• T/C-Layout • Pipes • Valves

Turbulent Flame Approach

Fischer and MIT Approach*

* Fischer, G.; Reibmitteldruck - Ottomotor; FVV-Vorhaben Nr. 629 Sandoval, D. et al.; An Improved Friction Model for Spark-Ignition Engines; SAE 2003-01-0725 ** Schmid, A. et al.; Ein neuer Ansatz zur Vorhersage des ottomotorischen Klopfens; Berlin, 2010

Detailed Engine Model Fuel Flow Map

Char. Line Max. Torque

Gas Exchange Map

Friction Map

BM

EP [b

ar]

Speed [RPM]

BM

EP [b

ar]

Speed [RPM]

BM

EP [b

ar]

Speed [RPM]

BM

EP [b

ar]

Speed [RPM]

Knocking

Knock Model by Schmid**



Gasoline Systems

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Engine Knock Model Knock Model based on Publication of A. Schmid* (enhanced Franzke Approach)

Only small Deviations between measured and simulated Center of Combustion

* Schmid, A. et al.; Ein neuer Ansatz zur Vorhersage des ottomotorischen Klopfens; Berlin, 2010

BM

EP

[bar

]

0

5

10

15

20

25

30

35

Engine Speed [RPM]1000 2000 3000 4000 5000 6000

-2

-2

-1

-1

-1

-1

0

0

0

0

22

2

2

1

1

1

∆ mfb50 [deg CA]

Matching Simulation vs. Measurement

Pre Reaction Integral (Franzke)

advanced by influence of turbulence on pre-reaction zone

with

∫=

=

⋅

⋅⋅⋅

=End

Start ereaction

d

epcn

IT

ba

PR

ϕϕ

ϕϕ ϕ

ϕ)(Pr

16

1

Empiric Knock Model

),,,,()(Pr ϕϕ relvunburnedburnedereaction VkTTfT =

r

v uuk

′=

0

)(ϕ 10 ≤≤ vk



Gasoline Systems

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Combustion Engine Model for Vehicle Simulation GT Map-based Engine Model (due to Simulation Time)

ICE

Air System Model • PT1-Element for Intake Manifold Dynamics • Gradient Model for Boost Pressure Increase

Torque Demand

VCO

Ignition Timing Model • TWC Heat-Up • Drive-Away • Idling Condition • Fast Torque Decrease

Fuel-Maps (based on

GMEP)

Gas-Exchange

TWC Model • O2-Increase while Fuel-Cut-Off • O2-Decrease by Fuel-Enrichment

Warmup Condition

-

+

Clutch

NSC Model (opt.) • NOx-Increase while Lean Operation • NOx-Decrease by Fuel-Enrichment

Engine Operation

Strategy (Lean Comb., CDA)

Friction

To Transmission



Gasoline Systems

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Overview vehicle model Vehicle model (GT-Suite)

Driving Profile • Driving Cycle • Driver (PI-Controller)

Control • Vehicle Control (Co-Simu- lation Matlab/Simulink) • Brake Control • Clutch Control

Vehicle • Transmission • Differential

eDrive and Powernet • Electric Machine • Battery • Electric Auxiliaries

Map-Based Engine • TWC / NSC • Gas Exchange Losses • Friction Losses • Spark Retard

Signal Bus



Gasoline Systems

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FC Advantage of (Stratified) Lean Combustion Simulation of FC-Map in SGDI-Mode with detailed ICE Model (1.4 l DI/TC)

BM

EP [b

ar]

0

2

4

6

8

10

12

14

Engine Speed [RPM]1000 2000 3000 4000 5000 6000

-25

-15

-15

-10

-10

-10

-10

-8

-8

-8

-5

-5

-5-3 -3

-3

-3

0

∆ BSFC [%]

λ 1.4

λ 1.4

F/C Advantage for Stratified 3… > 25 %, for Homogenous Lean 3…10 %

Modifications for Standard

ICE-Model*

Knock Model modified to consider

Charge Dilution

External EGR added for limiting NOx-Emissions

Combustion Model adapted

SI-Turbulent Flame

Throttle- and Wastegate Control adapted to Demands of SGDI-Operation

Stratified Lean (λ >> 1)

Homogenous Lean (λ > 1)

* Data for Matching of SGDI-Models based both on published Literature and on own Lean-Combustion Measurements with 1.2l DI/TC Mahle-Engine

To Torque

Coordinator



Gasoline Systems

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Modeling NSC (NOx-Storage-Catalyst) Simplified NSC-Model and Operation Strategy

Receive Torque

EngSpeed

NOx-Map* Op.Mode FuelCutOff

Receive Op.Mode

Receive FuelCutOff

StoredNOxMass

dtmm ∫=

+ NSCReg.

λ-Efficiency TorqueLoss

AFR to FuelMap

Fuel2NOx - πFuel Flow

From FuelMap

π

Calculating Waste Fuel

Flow

AFR

* Data for Matching of SGDI-Models based both on published Literature and on own Lean-Combustion Measurements with 1.2l DI/TC Mahle-Engine



Gasoline Systems

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Operation Strategy for SGDI Determination between SGDI and Homogenous λ-1 Operation

Vehicle Acceleration

(Forecast)

Drv.Cycle

Min. Max.

Engine Temperature

Vehicle Speed

NSC Loading

Op.Point Eng.Speed Eng.Torque

Engine FuelFlow

Operating Mode

Additional SparkRetard

NSC Regeneration

PMan (Lean)

PMan (λ-1)

Tim

e D

elay

du

e to

Air-

Sys

tem

D

ynam

ics

Analysis of NEDC with time based Mode-Switch Simulation

of WLTC not possible

Measure for WLTC: Bosch-Op.Strategy Reproduced Operating Strategy based

on different Engine Parameters

Results Switch between Hom. and Lean

Operation nearly exact Slight Differences in NSC-Regeneration



Gasoline Systems

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Predictive Operation Strategy in NEDC For new Driving Cycles or Driving Situations predictive Operation Strategy necessary

Predictive Operation Strategy suitable for Simulation of other Driving Cycle

SGDI

HOMOn

OffNSC-Reg

SGDI

HOMOn

OffNSC-Reg

vehi

cle

spee

d [k

m/h

]

0

40

80

120

SGDI/LeanHOM

NSC-Reg

vehi

cle

spee

d [k

m/h

]

0

40

80

120

time [s]0 120 240 360 480 600 720 840 960 1080 1200

∆ F/C < 0.5 %

* Altenschmidt, F. et al.; Das strahlgeführte Mercedes-Benz Brennverfahren – Nicht nur für den Schichtbetrieb entwickelt; 8. Tagung Diesel- und Benzin-Direkteinspritzung; Berlin, 2010

Published*

Bosch Operating Strategy



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Evaluation of Cycle-Simulation Split of Losses for Vehicle- and detailed Split of Losses for Engine-Simulation

Split of Losses for Evaluating best Operation Strategy and Optimization Potentials

Optimization measures

Increased CR, VCR

Combustion system, cEGR, thermal management

Spark retard (calibration)

Dethrottling: cEGR, Lean, VVT/VVL, CDA, eDZ, ...

Thermal management, auxiliaries, eDZ, …

Transmission

Recuperation potential

Required energy for vehicle drive

Ener

gy [k

Wh]

0

1

2

3

4

5

Time [s]0 240 480 720 960 1200

ideal isochoric process wall heat, real gas, comb. spark timing gas exchange engine friction powertrain brakes air drag rolling resistance

110 g CO2

Ene

rgy

[kW

h/km

]

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

115 g

G4

Ene

rgy

[kW

h/km

]

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

G5-3 SGDI



Gasoline Systems

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Results of SGDI-Simulation Split of Losses for SGDI-Engine for NEDC and WLTC

Benefit of SGDI 5.5 % in NEDC, about 4.5 % in WLTC (depending on calibration)

ideal isochoric process wall heat, real gas, combustion spark timing gas exchange engine friction powertrain brakes air drag rolling resistance

NEDC WLTC*

* All WLTC results are preliminary, since WLT-procedure is not finalized!

SGDI-Operation: • dethrottling main driver

for f/c benefit • additional f/c due to

NSC-Regeneration • potential in WLTC

depends strongly on calibration

4.4

%

5.5

%

1.4 l DI/TC 1.4 l SGDI/TC 1.4 l DI/TC 1.4 l SGDI/TC

Boundaries: Compact Class Vehicle (1330 kg), Manual Transmission

4.5

%

Eng. Disp.

No. of Cyl.

CR

DI/PFI

TC/NA

SGDI

COD



Gasoline Systems

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Outlook: HEV-Simulation High Diversification in Powertrain-Topologies requires overall System Optimization

Engine

Dual Clutch

E-Motor DCT

Clutch 1

> 100V

48V

Engine Clutch

MT

Engine eCS MT

14 V

48V BRS

PHEV - P2 w/ DCT

BRS on transmission side (w/ eCS)

Conventional Powertrain

Boost

e-Drive

Recuperation

Coasting

Powertrain-Topology Engine Configuration Operating Strategy

Hybrid-Drive

Min. CO2

14V



Gasoline Systems

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Conclusion

Standardized Simulation Methodology for detailed CO2-Potential Analysis

Detailed general Engine Model for Comparison of State of the Art Engine Concepts Combustion Knocking Friction

Map Based Combustion Engine Model and Vehicle Model for Cycle Simulation

Analysis of Lean Operation Mode was presented as an Example NSC-Model Operation Strategy

Comparison of conventional λ = 1 turbocharged DZ Engine with SGDI shows a CO2-potential of 5.5 % in NEDC and 4.5 % in WLTC*

* All WLTC results are preliminary, since WLT-procedure is not finalized!



Gasoline Systems

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Thank you for your attention

Documents

Modeling and Analysis of a Lean Combustion Engine by ... · Lean Combustion Modeling . Gasoline Systems . 7 Combustion Engine Model for Vehicle Simulation GT Map-based Engine Model