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