June, 2010

Dual Clutch Transmission Technological Advantages and

Implementation Strategies

2

Electro-Hydraulic Controls for

DCTs

Michael Ritschel

3

Terminology

Electro-hydraulic controls for wet and

dry DCTs

Electro-hydraulic controls

w/ steady state pump

(„Low pressure“ systems)

Electro-hydraulic controls

w/ on demand pump

(„High pressure“ systems)

Wet DCT Wet DCT

Dry DCT

LP System HP System

4

Electro-Hydraulic Principle

Electric Hydraulic

electric

current

Output Power Input Signal

solenoid

armature

spool

hydraulic

flow/pressure

Fmagnetic

Fhydraulic

5

Outline

Electro-Hydraulic Controls LP Systems

- Steady State Pump - Power Supply

DCT Power Flow

Controls Modules

Controls Functions w/ Examples

Electro-Hydraulic Controls HP Systems

- On Demand Pump - Power Supply

DCT Power Flow

Controls Modules

Controls Functions w/ Examples

6

LP System - Main Characteristics

Mechanically Driven Pump

Pump Sizes ~12-18 cc/rev

Maximum Line Pressure 15-20 bar

System Leakage

Combined Oil Circuit with Gear Set

Oil Contaminated with Wear Particles

7

Power Supply - LP System

Steady State Pump

„Low Pressure“ - LP System

Engine

Hydraulic

Control

Module

(HCM)

Pump

p_Line

max. line pressure (e.g. 20bar)

time

p_Line (normal operating)

p_Clutch

pre

ssure

Engine On = Pump On

Pump

Drive

8

DCT Power Flow - LP System

Engine

LP System w/o Integration

Hydraulic

Control

Module

Gears Wet

Clutch

Transmission Control Unit

TCU Engine Control Unit

ECU

Ac

tua

tio

n

Lu

be

Ge

ar

Ac

tua

tio

n

Shift

Forks

Oil Circuit

Generator

Battery

Gear Lubrication

Cooling

9

DCT Power Flow - LP System (Options)

Engine

LP System

Hydraulic

Control

Module

Gears Wet

Clutch

Transmission Control Unit

TCU

Engine Control Unit

ECU

Ac

tua

tio

n

Lu

be

Ge

ar

Ac

tua

tio

n

Shift

Forks

Oil Circuit

Generator

Battery

Gear Lubrication

Cooling

w/ Integrated TCU, Integrated Gear Actuation

10

DCT Controls Examples - LP System

DCT Controls Examples

„Low Pressure“

Integrated TCU

w/o integrated

gear actuation

Integrated

TCU

Integrated

gear actuation

Integrated

gear actuation

w/o integrated

TCU

11

DCT Controls Functions - LP System

Filtration

Main Pressure Control

Clutch Cooling

Gear Actuation

Clutch Control

12

LP System - Filtration

Sump

Suction Filter

Pump Pressure Filter

Option2 (Control Circuit)

Oil Cleanliness Requirement

acc ISO 4406 xx/19/16

Oil Volume 5-7 liters

Pressure Filter

Option1 (Bypass)

Line

Main Pressure Regulator Second

Priority

Suction

Pilot Pressure

13

LP System - Filters

ß15 > 200 (99,5%)

Flow > 1.5 l/min

Exchangable

Mesh size ~ 60 -150 µm

Flow > 40 l/min

Lifetime

Suction Filter

Pressure Filter

Source Filtran

14

Main Pressure Regulator

LP System - Main Pressure Control

p_Line

Second

Priority

Suction

Variable Bleed Solenoid (VBS)

Normally High (NH)

15

LP System - Main Pressure Control

current VBS

pre

ssure

VB

S ~9 bar

~1.2 A

VBS Characteristic

NH

Line Pressure Characteristic

Line Sweep

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

9,0

10,0

11,0

12,0

13,0

14,0

15,0

16,0

17,0

18,0

19,0

20,0

21,0

22,0

23,0

24,0

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 1,1 1,2

Current VBS(A)

Lin

e P

res

su

re (

bar)

16

LP System - Clutch Cooling

p_Line

Pump Flow

Lube Regulator

Variable Force Solenoid (VFS) Low-Flow

Normally High (NH)

Clutch

Lube

Cooler /

Gear

Lubrication

17

LP System - Clutch Cooling

current VFS LF

~1.2 A

~8 bar

pre

ssure

VF

S L

F

VFS Low-Flow

Characteristic NH

Lube Flow Characteristic Lube Sweep

0,000

5,000

10,000

15,000

20,000

25,000

0,000 0,200 0,400 0,600 0,800 1,000 1,200

Current VFS LF [A]

Lu

be

Flo

w [

l/m

in]

18

LP System - Solenoids

Open-End VBS Low-cost option for Line,

Lube, Axis Feed and Cut-Off control

Low-Flow VFS Exceptional accuracy

across temperature and pressure ranges

Low leakage

Line, Lube, Axis Feed and Cut-Off control

Mini Direct-Acting VFS (MDA)

Low-Flow VFS

Open-End Variable Bleed

Solenoids (OE VBS)

19

LP System - Gear Actuation

p_Line

Multiplex Actuation

MPx 1 On/Off Sol

5 4 2 6 R 1 3 N

Actuator Multiplex Valve #2

MPx 2 On/Off Sol

Actuator Multiplex Valve #1

Act 1VBS Normally Low

Actuator 1 Regulator

Actuator 2 Regulator

Act 2 VBS Normally Low

Shift Forks

On/Off Solenoids

VBS

Normally Low (NL)

20

LP System - Multiplex

current VBS

pre

ssure

VB

S ~9 bar

~1.2 A

VBS Characteristic

NL

Axis Feed Pressure

Characteristic

Axis Feed Pressure

0,000

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

20,000

0,000 0,200 0,400 0,600 0,800 1,000 1,200

Current VBS [A]

Axis

Fe

ed

Pre

ss

ure

[b

ar]

21

LP System - Gear Actuation

Direct Access Actuation

p_Line

Shift Forks

6 4

Act 1VBS Normally Low

Actuator 1 Regulator

Actuator 2 Regulator

Act 2 VBS Normally Low

5 2 R 1 3 N

ACS 1 ACS 2 ACS 3 ACS 4

Area Control Solenoid (ACS)

22

LP System - Direct Access

ACS Characteristic

0

1

2

3

4

5

6

7

8

9

10

0 0,2 0,4 0,6 0,8 1 1,2

Current ACS [A]

Flo

w A

CS

[l/m

in]

ACS Flow Characteristic

23

LP System - Solenoids

On/Off Solenoids

Low-cost option for

gear actuation control

Multiplexing control

Area Control

Solenoids (ACS)

Acurate control of

piston velocity

Lube flow control

Area Control Solenoids (ACS)

On/Off Solenoids

24

LP System - Clutch Control

Direct Clutch Control

VFS odd VFS even

Clutch Odd Clutch Even

p_Line

Variable Force Solenoid (VFS) - High Flow

25

Odd AF VFS Sweep

0,0

2,0

4,0

6,0

8,0

10,0

12,0

14,0

16,0

18,0

20,0

22,0

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 1,1 1,2 1,3 1,4 1,5

Current VFS (A)

Pre

ssu

re C

lutc

h (

Ba

r)

Odd Reg Sweep Line Pressure

LP System - Clutch Control

Clutch Pressure Characteristic

VFS High Flow

26

LP System Solenoids

VFS High Flow

Ideal for direct clutch

control

Fast and stable clutch

filling performance

Exceptional accuracy

across temperature and

pressure ranges

Low leakage

High-Flow VFS

27

Outline

Electro-Hydraulic Controls LP Systems - Steady State Pump - Power Supply

DCT Power Flow

Controls Modules

Controls Functions w/ Examples

Electro-Hydraulic Controls HP Systems - On Demand Pump- Power Supply

DCT Power Flow

Controls Modules

Controls Functions w/ Examples

28

HP System - Main Characteristics

E-Motor Driven Pump (on demand)

Pump Sizes ~ 1.5-3 cc/rev

Maximum Line Pressure > 40 bar

Accumulator Size ~ 200 - 500 ccm

Very Low System Leakage

Separate Oil Circuit for Controls

High Oil Cleanliness Required

Low Viscosity Oil

29

Power Supply - HP System

min. line pressure (e.g. 40bar)

On Demand Pump (w/ Accumulator)

„High Pressure“ - HP System

M

Hydraulic

Control

Module

(HCM)

Power Pack

Accumulator

E-Motor Pump

p_Line

Pump On

time

max. line pressure (e.g. 60bar)

p_Line

pre

ssure

p_Clutch

Pump Off

30

DCT Power Flow - HP System

Wet Clutch System

Engine Control Unit

ECU

Hydraulic

Control

Module

Engine Gears Wet

Clutch

Transmission Control Unit

TCU

Ac

tua

tio

n

Ge

ar

Ac

tua

tio

n

Shift

Forks

Oil Circuit I

Generator

Battery

Oil Circuit II

Lu

be

31

DCT Power Flow - HP System

Dry Clutch System

Hydraulic

Control

Module

Engine Gears Dry

Clutch

Transmission Control Unit

TCU Engine Control Unit

ECU

Ac

tua

tio

n

Ge

ar

Ac

tua

tio

n

Shift

Forks

Generator

Battery

Oil Circuit II

Oil Circuit I

32

HP Module typical content

• HP solenoids

• Actuation pistons

• Position sensors

• Pressure sensors

• Shifter valve(s)

• Electric motor

• High pressure pump

• Line pressure accumulator

DCT Controls Example - HP System

33

HP Module key features

•Electric on-demand pump

•High Efficiency - Very low

leakage

•Compatible with stop /

start functions

•Compatible with both wet

and dry DCT HP systems.

•Potential application

outside DCT

DCT Controls Example - HP System

34

DCT Controls Functions HP

Filtration

Accumulator / Main Pressure Control

Gear Actuation

Clutch Control

35

HP System - Filtration

Oil Cleanliness Requirement

acc. ISO 4406 xx/17/13

Oil Volume 2-3 liter

(separate oil circuit)

M

Sump

Pump

Pressure Filter

Accumulator

ß10 > 200

Lifetime

p_Line

Source Hydac

E-Motor

36

HP System - Accumulator

Diaphragm

Accumulator

Piston

Accumulator

Source

Freudenberg

Accu Characteristics

0,00

100,00

200,00

300,00

400,00

500,00

600,00

0 10 20 30 40 50 60 70

Pressure [bar]

Accu

Vo

lum

e [

cm

^3]

37

HP System - Accumulator

0

50

100

150

200

250

0 10 20 30 40 50 60 70 80

Pressure [bar]

de

lta

Oil

Vo

lum

e [

cc

.]

90 20 -20

Temperature [癈 ]

Volume per shift

~20cc

38

HP System - Gear Actuation

Press Cont Sol Press Cont Sol

P_Line

Odd Gears and Clutch Even Gears and Clutch

Area Cont Sol Area Cont Sol Area Cont Sol Area Cont Sol

Flow Characteristic ACS

~10l/min

AC

S F

low

ACS Current

~2A

39

HP System - Clutch Control

Clutch Control

Press Cont Sol Press Cont Sol

p_Line

Clutch Pressure Characteristic

VFS

40

HP System - Solenoids

Fully Sealed

Pressure & Flow Control

Partially Sealed

Pressure & Flow Control Fully or Partially Sealed

On/Off

System Pressures Up To 100 bar

Control Pressure Range Up To 60 bar

Flow > 10 L/min at 10 bar P

De-Energized Leakage < 8 cc/min

Fully Sealed, Partially Sealed and

Unsealed Designs

41

HP System - Low Leakage

Cartridge Design

Very Low Clearance

Between Spool and

Sleeve

Axial Distances

Optimized