BorgWarner DCTWet ClutchesFrictionMtrls Gold (1)

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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Dual Clutch Function


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Slide 3

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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Slide 4

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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Slide 7

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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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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Slide 16

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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Slide 23

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

Module X


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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

Module X


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Slide 39

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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Slide 40

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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Slide 41

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

Module X


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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

Module X


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better fuel economyreduced emissions

great performance

Thank you!

BorgWarner DCTWet ClutchesFrictionMtrls Gold (1)

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Transcript of BorgWarner DCTWet ClutchesFrictionMtrls Gold (1)