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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
1
Modeling and Analysis of a Lean Combustion Engine by Combining Engine and Vehicle Simulation
GS/ESC2 - Jens Tophoven
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
Gasoline Systems
2
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
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.
COD
Lean Combustion Modeling
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
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
Gasoline Systems
4
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
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
Gasoline Systems
5
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**
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
Gasoline Systems
6
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
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
Gasoline Systems
7
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
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
Gasoline Systems
8
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
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
Gasoline Systems
9
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
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
Gasoline Systems
10
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
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
Gasoline Systems
11
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
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
Gasoline Systems
12
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
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
Gasoline Systems
13
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
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
Gasoline Systems
14
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
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
Gasoline Systems
15
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
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
Gasoline Systems
16
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!
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
Gasoline Systems
17
Thank you for your attention