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7/22/2019 BorgWarner DCTWet ClutchesFrictionMtrls Gold (1)
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Slide 0
Dual Clutches and Friction Materials
Wet DCT
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Slide 1
Content
Function of a Dual Clutch
DC Architecture
Clutch Sizing
Thermal Simulation
Wet versus Dry
DC Wet Friction Material
DC Trends and New Developments
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Slide 2
Dual Clutch Function
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Principle of Dual Clutch
2 clutches, each of them connected to a transmission shaft
Independent opening and closing of clutches
Very smooth shifting no power flow interruption
Clutches = launch clutches;
no TC required
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Dual Clutchmain components
PistonsActuation of clutches
Main hubDistribution of oil flows
Return SpringsOpen the clutches
Clutch packsFriction and Separator
plates for torque transfer
Clutch HubsConnection to
transmission shafts
Input hubConnection to engine
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Actuation of Outer Clutch
Pressure Oil
Piston Ring OC
movement
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Actuation of Inner Clutch
Piston ring IC
movement
Pressure Oil
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Cooling of Clutches
Lube Oil
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Architecture ofWet Dual Clutches
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Traditional architectures
Nested vs Parallel
Clutch packs
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Clutch pack architecture
nested parallel
more efficient use of cooling flow
both clutches same thermal capacity
shorter axial length smaller outer diameter
smaller inertias to be synchronized
lower cost
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DualTronic PowerSplit Transmission
2 single clutches
Driven by a chain
Small and micro cars
Compact transmission design
Lower torque applications (~200Nm)
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Clutch conceptsw/o support with support
nested
parallel Technically possiblebut long axial dimension
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Slide 13
Clutch Sizing
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Clutch capacity calculation
G = Md / p = * zf* AAp* rmean
pmax,st = pmax - pspr
AAp = apply piston area
Md = * zf* p * AAp* rmean
rmean= 2 / 3 * (r3f,outr
3f,in) / (r
2f,outr
2f,in)
= friction coefficient
Zf = number of friction surfaces
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Odd Clutch
0.000
0.200
0.400
0.600
0.800
1.000
1.200
1.400
1.600
1.800
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 1000
0
1100
0
1200
0
Drehzahl [U/min]
Druck
[bar]
resultierender Zentrifugaldruck
Federdruck
Federdruck - res. Differenzdruck
Even Clutch
-4.000
-3.000
-2.000
-1.000
0.000
1.000
2.000
3.0004.000
5.000
6.000
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 1000
0
1100
0
1200
0
Drehzahl [U/min]
Druck[bar]
resultierender Zentrifugaldruck
Federdruck
Federdruck - res. Differenzdruck
Clutch hydraulic balancing
Fc= m * v2/ r
Pressure
chamber Balance
chamber
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Thermal Simulation
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Simulation (hill hold and launch)
2400 U/min
141 C
4000 U/min @ 5s
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Simulation (race start)
4500 U/min
142 C
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Wet vs Dry
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Main characteristicsWet Clutch* Dry Clutch**
compact size actuation system space demanding
cooling lubricant no lubricant
high energy inputs possible limited use
all vehicle classes limited use
pump to circulate cooling oil required ambient air cooled
minimal wear high wear
*w ith hydraulic piston actuation system **w ith release system
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Projects in series production
Nm
rpm
6000
7000
8000
9000
100 300 500 700 900 1100
BW Wet DCT
Wet DCTDry DCT
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Slide 22
Friction Material
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Current Trends in Transmissions and Requirements of
Wet Friction Materials
TRANSMISSION TRENDS WET FRICTION MATERIAL REQUIREMENTS
Higher pressures Low deformation, low lining loss
Improved efficiency
Smaller pump, lower ATF flow Higher energy facings, higher heat resistance at low lubrication flow
Reduce drag loss Improved groove pattern design
Reduced size/weight Higher , increased heat resistance
Higher speeds, higher energies Stable coefficients of friction, no hot spots
Continuous slip clutches Good V; no shudder; no noise
ATF compatibility Inert to chemical and physical interactions with fluids
Better consistency of shift qualityBetter PVT stability, positive -V slope; reduced variation under
various conditions
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Development of Todays High Heat Resistance and High
Performance Friction Materials
FRICTION PROPERTYWET FRICTION MATERIAL CONTROLLING
FACTORS
o, low speed dynamic coefficient Friction material ingredients and ATF additives adsorption
i, initial dynamic coefficient at high speed Hydrodynamic effects / porosity / compression / roughness
Mechanical strength Fiber type, fiber fibrillation, fiber / resin bond strengths
Heat resistance More synthetic fibers (aramid, carbon), higher porosity
Positive -V slope Balance of paper ingredients with ATF additives adsorption and poresize
Hot spot resistance Resiliency, oil film
Glazing Ingredient compatibility with ATF additives, pore size
Compression set Optimization of fibers/, fillers and resins type / amounts
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ATF additives
Friction Material chemical effects
Smoothness/uniformity
ATF film
Lining permeability
Compressibility
Groove effects
Surface Smoothness
0 0.2 0.4 0.6 0.8 10
100
200
300
Time (seconds)
Torque(Nm)
Asperity Torque
Hydrodynamic
Torque
Total Torque
Controlling Factors for Engagement
Torque Curve Slope
Time (seconds)
Torque(Nm)
Lining permeability
Compressibility
Groove effects
Surface Smoothness
ATF additives
Friction Material Chemical effects
Smoothness/uniformity
ATF film
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Slide 26
BWs Unified Friction System Model
RegionI
OilFilm
RegionII
OilFilm
RegionIII
OilFilm
RegionIV
Oil Film
RPM
DragTorque
RegionI
Full Oil
Sheet
RegIII
Rivulet
Sheet
RegionIV
NoOil Sheet
RegII
Tran-
sition
Interface Temperature vs Time
0 20 40 60 80 1000
50
100
150
200
250
300
Time-Seconds
il
Thermoelastic
InstabilityThermoplastic
Instability
TEI: No Functional
Problem, NotProgressive
TPI: Distortion,
Progressive ThermalDamage
Temperature
Prediction
ENGAGE_W
Model
Heat Transfer
Coefficients
Torque
Model
Breakaway
Coefficient
Thermal
Degradation
Open Pack
Drag
Effectof friction materialpermeability ont he engagementofa wet clutch as predicted byhydrodynamic models
Torque Response Curve Shapes
0
50
100
150
200
250
300
350
400
450
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Time (s)
Torque(Nm)
Increasing friction material permeability
Pressure
Speed
Permeability Test Set Up
Ring Sample
63 mm
82 mm
63 mm
82 mm
Fluid: Water
Fluid Pressure: 230 kPaFluid Volume: 292 cm3
Sample Pressure: 620 kPa
LateralPermeability Set Up
Optimizedgroove
pattern for
drag loss
Determine
interface
temperature
Determine
torque
characteristics
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DCT Material Requirements
Interface Temperature
Deterioration
DualTronic
friction material
Conventional
friction material
Durability
Increase surface adsorption
for ATF modifiers
No glazing
Heat Resistance Ingredients
Controllability
High lining dimensional stability
Positive -v slope at various
pressure and temperature
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Oil flow effects on temperature
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ATF Flow
Improved Heat
Resistance
Anti-Shudder
Characteristics
Internal Structure
Surface Texture
High TemperatureSynthetic Fibers
High Porosity
Surface Friction Modifier/Filler
DCT Material
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Friction Coefficient after Durability Test
Slip Speed [rpm]
FrictionCoeffic
ient
Positive m-v slope is
desirable
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Materials and Groove Pattern
Conventional
- lower porosity
- simple groove pattern- standard materials
DCT
- high porosity, higher elasticity
- complex groove pattern
- special material composition
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DCT material launch charactertics
Laun
chtorquec
urves
8L/min.o
il,
hightemperature
Conventional material DCT material
Start of test Start of test
End of testEnd of test
Stable,
desirable
torque shapespeed
torque
Torque
vibration
M d l X
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Launch Durability 8 L/min. Oil
-0.0025
-0.002-0.0015
-0.001
-0.0005
0
0.0005
0.001
0.0015
3000 5000 7000 9000 11000 13000
Cycles
COFGr
adient(500rpm-200rpm)
Conventional
DCT
More robust positive -
v gradient
M d l X
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Carbon Woven material not desirable
Carbon Woven
Sliding Speed Sliding Speed
DCT Material
Low
coefficient
Negative -v,
potential for
shudder
High lining
loss due tocompression0.005 0.011 0.027 0.055 0.110 0.164 0.219 0.274 0.482 0.548 0.712 0.958 1.205
1.643
415
774
1933
2956
0.110
0.1150.120
0.125
0.130
0.135
0.140
0.145
0.150
0.155
0.160
0.165
0.170
0.175
0.180
FRICTIONC
OEFFICIENT(?
SLIDING SPEED (m/s)
SURFACE PRESSURE (kPa)
M d l X
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Effect on -V Characteristics by Creating More ATF
Additives Adsorption Sites for Friction ModifiersMid Pressure (1.0MPa) at 90C
0.00
0.05
0.10
0.15
0.20
0 0.1 0.2 0.3 0.4 0.5Speed (m/s)
Coefficien
t-of-Friction
New Oil / New Material
Mid Pressure (1.0MPa) at 90C
0.00
0.05
0.10
0.15
0.20
0 0.1 0.2 0.3 0.4 0.5Speed (m/s)
Coefficient-of-Friction
Damaged FM Oil / New Material
Mid Pressure (1.0MPa) at 90C
0.00
0.05
0.10
0.15
0.20
0 0.1 0.2 0.3 0.4 0.5
Speed (m/s)
Coefficient-of-F
riction
Damaged FM Oil / Greater Surface Enhancement
New OilStandard Plate
Degraded OilStandard Plate
Degraded Oil-Surface EnhancedPlates with moreadsorption sites
M d l X
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DCT Material Analyses After Durability Test
SEM/EDS X-ray
#662
Coun
ts
Energy (KeV)
Coun
ts
Energy (KeV)
No Glazing
No surface
accumulation of
P.S from degraded
ATF
Energy Densities (j/mm2)5.83
Oil Temperature 100C
Speed (rpm) 3,300
Slip time (seconds ) 7-10
sec
Porous
surface
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Summary
High temperature launches
Noise Resistance
Creep resistance
Good Durability
Enablers
New Tribological Characterization Methods
Advanced Friction Interface Phenomena Understanding
Predictive Methods and Model
High Performance DCT
Composite Friction Material
DCT
Shifting Clutches
Slipping Clutches
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Slide 38
Trends
new developments
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Micro / Small Class Vehicle
Main Vehicle Class Micro, Small
Max Engine Torque 140 Nm
Vehicle Weight 1150 kg
Maximum Weight 1650 kg
Trailer Weight 1000 kg
Vehicle for Analysis
Max Transmission Input Torque = 170 Nm
Module X
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High Efficiency DualTronic
Drag Loss ReductionOptimized Groove PatternHigh Precision
Cooling Flow Control
Reduced Cooling Flow Smaller Pump Size Reduced Leakage
High Pressure ActuationElectro Hydraulic SystemElectric Flow Pump
Based on existing
DualTronic Technology
Efficiency
Improvement
Clutch Controls
Module X
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Efficiency
60%
65%
70%
75%
80%
85%
90%
95%
100%
19% 20% 21% 22% 23% 24% 25%
NEDC Engine Efficiency [%]
NEDCTransmissionEfficiency[%
Transmissions
20%
19%
18%
17%
16%
15%
Constant
Overall
EfficiencyLines
MT
HEDCT+HP
DRY DCT+HP
HEDCT
WET DCT
CVT-WSC
CVT-T/C
AT (NIC+L/U)
AT
DCTs with best
overall efficiency
from fuel to wheels
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WetHigh EfficiencyDry
96,8%
94,6%
92,5%
93,3%
90%
92%
94%
96%
98%
100%
WET DCT
2008
HEDCT HEDCT
HP ACT.
DRY DCT
HP ACT.
FuelConsumption[%
New Friction Mat.
Red. Leakage
High Pre. Flow Ctrl.
Pump On-Demand&
Flow On-Demand
Ratio Limitation
Higher Inertia
MT
Module X
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Break-up of Losses in NEDC
0
100
200
300
400500
600
700
800
WET
DCT
HEDC
T
HEDC
THP
ACT
.
DRYDC
THP
ACT
.
Energy [kJ] Flow Pump Elec.
Act. Pump Elec.
Flow + Act. Pump Mech.
DCT Inertia
Drag (Hyd. + Bearings)
Creep Torque
Gearbox Losses
TCU + Solenoid
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better fuel economyreduced emissions
great performance
Thank you!