optimization studies of engine friction...total engine friction, strip-down test. optimization...
TRANSCRIPT
M.Sc. Oleg Krecker, PhD candidate, BMWB.Eng. Christoph Hiltner, Master’s student, Affiliation BMW
OPTIMIZATION STUDIES OF ENGINE FRICTIONEUROPEAN GT CONFERENCE FRANKFURT/MAIN, OCTOBER 8TH, 2018
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 2
AGENDA
Motivation and objective1
Improvements on preliminary results2
Friction reduction studies with GT-SUITE’s Integrated Design Optimizer 3
Conclusion and further developments4
MOTIVATION
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 3
Thermal engine model
1D Simulation warm up & fuel consumption within driving cycles
Test
Warm up
0 200 400 600 800 1000 12000
50
100
150
Zeit [s]
TH
_Z
ST
_1
_2
_0
5 [°C
]
m.TH_ZST_1_2_05
Tem
pera
ture
[°C]
Time [s]
Cylinder Liner Temperature, NEDC
Simulationdata
Final result:
Impact on CO2 - emissions
Corre
latio
n &
valid
atio
n
Predictive evaluation of concepts and trends in engine friction reduction„As simple as possible and as complex as necessary“
other losses
mech. power
Piston assembly
Crank-shaft
Oil + vacuum
Belt driveCylinder head+ chain drive
Measurement data (motored and fired)
Fric
tion
Speed
pump
Friction
Low
Total engine
fired
1-cylinder fired(floating liner)
Total engine / strip-down
Single components motored
Transient cycles
Low High
Real boundary conditions
Data resolution &reproducibility
High
Measured
Pred
icte
d
0D/1D Friction Simulation Total engine
GT-SUITE
Crucial formodel calibration
0D/1D Friction SimulationOBJECTIVE
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 4
Low
Total enginefired
1-cylinder fired(floating liner)
Total engine / strip-down
Single components motored
Transient cycles
Low High
Closeness of basic conditions to reality
Possible measuring resolution & reproducibility
High
Fast prediction
Agile transferability
Relative comparison
Physical evaluation
Requ
irem
ents
Validation Calibration OptimizationFriction
Advanced parameter analysis using GT-SUITE Integrated Design Optimizer (IDO)
Systems
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 5
AGENDA
Motivation and objective1
Improvements on preliminary results2
Friction reduction studies with GT-SUITE’s Integrated Design Optimizer 3
Conclusion and further developments4
PRELIMINARY RESULTSTOTAL ENGINE FRICTION, STRIP-DOWN TEST
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 6
Total Engine Test Rig Transmission Oil- & Vacuum – Pump Water pumpAcc. Belt Drive Inlet Camshaft + ValvetrainExhaust Camshaft + ValvetrainBalancer Shaft Piston SkirtPiston RingsSmall End BearingBig End Bearing Main Bearings Seals
Sim
ulat
ion
Expe
ri-m
ent
Strip-Down Test, 90°C
1000 2000 3000 4000Speed [rpm]
Fric
tion
Torq
ue [N
m]
Necessary model improvements:
Fric
tion
dist
ribut
ion:
pr
evio
us m
odel
ass
umpt
ion
� Buildup� Parameter
identification� Validation
� Further investigation on model parameters
� Validation of single camshaft friction
� Parameter identification
� Extend measurements for validation
Gap due to:− Missing simulation of chain friction.− Non-validated belt drive friction model.− Inaccuracies between single state strip-down
measurements, total engine friction behavior and its equivalent simulation.
PRELIMINARY RESULTSTOTAL ENGINE FRICTION, STRIP-DOWN TEST
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 7
Total Engine Test Rig Transmission Oil- & Vacuum – Pump Water pumpAcc. Belt Drive Inlet Camshaft + ValvetrainExhaust Camshaft + ValvetrainBalancer Shaft Piston SkirtPiston RingsSmall End BearingBig End Bearing Main Bearings Seals
Sim
ulat
ion
Expe
ri-m
ent
Strip-Down Test, 90°C
1000 2000 3000 4000Speed [rpm]
Fric
tion
Torq
ue [N
m]
Gap due to:− Missing simulation of chain friction.− Non-validated belt drive friction model.− Inaccuracies between single state strip-down
measurements, total engine friction behavior and its equivalent simulation.
Necessary model improvements:
Fric
tion
dist
ribut
ion:
pr
evio
us m
odel
ass
umpt
ion
� Buildup� Parameter
identification� Validation
� Further investigation on model parameters
� Validation of single camshaft friction
� Parameter identification
� Extend measurements for validation
0 1000 2000 3000 4000 5000
Camshaft + valvetrain frictionTorque
transducer
CHAIN DRIVE FRICTION MODEL
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 8
Validation Method
In chain-guide/sprocket contacts:- Friction coefficient guides- Friction coefficient sprocketsIn chain links: - Longitudinal damping- Torsional damping
Main friction/power loss parameters
Modelling
Strip-Down states Single component motored
Torquetransducer
Feasible magnitude and slope of chain drive power loss.
Inaccuracies due to missing system interdependency (e.g. chain tensioner dynamics).
Speed [rpm]
Pow
er lo
ssch
ain
drive
[W
]IDO Calibration
subtract subtract
Torquetransducer
0 1000 2000 3000 4000 5000 6000
FEAD FRICTION MODEL
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 9
Validation MethodModelling
Single component motored
In belt-pulley contacts:- Friction coefficient- Contact damping In belt properties: - Bending stiffness- Shearing stiffness- Longitudinal damping
Main friction/power loss parameters
Friction torque of each accessory
Speed [rpm]
Pow
er lo
ssFE
AD [W
]
IDO Calibration Feasible magnitude FEAD power loss.
Inaccuracies due to missing system interdependency (e.g. accessory roller bearing).
CURRENT RESULTSTOTAL ENGINE FRICTION, STRIP-DOWN TEST
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 10
Necessary model improvements:
Buildup Parameter
identification Validation
Parameter identification
Extend measurements for validation
CURRENT RESULTSTOTAL ENGINE FRICTION, STRIP-DOWN TEST
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 11
Strip-Down Test, 90°C
1000 2000 3000 4000Speed [rpm]
Fric
tion
Torq
ue [N
m]
Total engine, measuredRemaining components, measuredMain components, simulated
Acc. Belt Drive Chain DriveCylinder Head UnitPiston AssemblyBalancer Shaft Crankshaft
Necessary model improvements:
Buildup Parameter
identification Validation
Parameter identification
Extend measurements for validation
1000 2000 3000 4000Speed [rpm]
Fric
tion
Torq
ue [N
m]
1000 2000 3000 4000Speed [rpm]
Fric
tion
Torq
ue [N
m]
1000 2000 3000 4000Speed [rpm]
Fric
tion
Torq
ue [N
m]
Cylin
der H
ead
+Ch
ain
Bala
ncer
Sha
ftCr
anks
haft
Test Rig Transmission Oil- & Vacuum – Pump Water pump
- Correlation of measurement and simulation has been improved. - Single component friction simulation shows feasible agreement
to measured data. - Note: magnitude and trend of single component friction has to be
questioned critically if compared to total engine friction losses.
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 12
AGENDA
Motivation and objective1
Improvements on preliminary results2
Friction reduction studies with GT-SUITE’s Integrated Design Optimizer 3
Conclusion and further developments4
0 2000 4000 6000
GT-SUITE INTEGRATED DESIGN OPTIMIZERSETTINGS FOR FEAD MODEL
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 13
Variables forcalibration
i = 15
Variables forpower loss reduction
i = 7
Search algorithm Genetic, NSGA-III
Population size 50
Number of generations 10
Variables forcalibration
i = 7
1st loop 2nd loop Example parameters:LuGre friction coefficient, belt damping coefficient, belt-pulley connection damping ratio, …
Example parameters:LuGre friction coefficient, belt damping coefficient, belt shear stiffness, belt axial stiffness, …
0
1
2
3
4
0 300 600
Design [-]
Obj
ectiv
e fu
nctio
n [W
]*10
5
0
200
400
600
800
1000
0 300 600
Design [-]
Obj
ectiv
e fu
nctio
n [W
]
Speed [rpm]
Pow
er lo
ss [W
]
(*)
(*hypothetical, no-constraint study)
0 2000 4000 6000
Speed [rpm]
Pow
er lo
ss [W
]
Best design Base design TargetCalibrated design
Calibrated design
No-constraint design
Constraintdesign
VARIATION STUDIESFEAD FRICTION MODEL
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 14
0 1000 2000 3000 4000 5000 6000
meas., 222N meas., 316N
sim., 222N sim., 316N
Speed [rpm]
Pow
er lo
ssFE
AD [
W]
0 1000 2000 3000 4000 5000 6000
meas., 222N meas., 217N, 2nd Layout
sim., 222N sim., 217N, 2nd Layout
Speed [rpm]
Pow
er lo
ssFE
AD [
W]
Belt pre-tension Belt layout
Higher pre-tension leads to more power losses. Good correlation in mid to high speed ranges. Further investigation on low speed power losses necessary.
Less power losses by removing a pulley and changing the belt layout (e.g. remove water pump in case it is electrically driven).
Good correlation in mid to high speed ranges. Further investigation on low speed power losses necessary.
0 1000 2000 3000 4000 5000 6000
OPTIMIZATION STUDIESFEAD FRICTION MODEL
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 15
Speed [rpm]
Pow
er lo
ssFE
AD [
W] - 80%
power loss
FEAD power loss minimization
Idea
Resu
ltsCr
itica
lco
nclu
sion
Inner belt power dissipation is determined by the belt material properties. Soft belt (less axial stiffness, less shear stiffness) might decrease power losses.
Parameter comparison base design vs. best design:1. Axial stiffness & LuGre friction coeff. comparable magnitude. 2. Shear stiffness & belt damping significantly lower in best design. More than 80% power loss reduction.
Torque transmission of soft belt still sufficient? Belt slip rate? Functionality of accessories assured?Fatigue strength in long terms?Wear?
Calibrated design
No-constraint design
Constraintdesign
METHODOLOGYWORKFLOW IMPROVEMENTS
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 16
Simulation model
f(x1, x2…)
Known parameters
Assumptions
“Tuning factors”
Sensitivity
Inte
rdep
ende
ncy
Parameter categorizing
Sensitivity analysis
Validation Parameter identification
Calibration OptimizationFriction
Enhanced simulation engineering
Variables forcalibration
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 17
AGENDA
Motivation and objective1
Improvements on preliminary results2
Friction reduction studies with GT-SUITE’s Integrated Design Optimizer 3
Conclusion and further developments4
CONCLUSION AND FURTHER DEVELOPMENTS
Optimization Studies of Engine Friction | Oleg Krecker | October 8th 2018 Slide 18
Conclusion
− All major friction components of a modern petrol engine have been modelled within GT-SUITE.
− GT-SUITE’s Integrated Design Optimizer is a powerful tool for extensive parameter studies of each friction sub-model. But comprehensive definition of parameter range and magnitude is challenging (usually due to lack of data).
− Current workflow of model parameter studies will be enhanced by extended sensitivity analyses.
Final parameter freeze of friction
sub-models
Model calibration and proof of friction
prediction
Validation of secondary model outputs (besides
friction)
Development of a friction optimized
engine design concept
Further investigation on
design regarding feasibility
Furth
er d
evel
opm
ents