The document discusses optimizing a wet dual clutch transmission (DCT) fluid through testing and formulation. Tribometer testing was used to evaluate fluid performance, showing positive and negative engagement characteristics. Fluid formulations included additives for friction modification, wear protection, and other properties. Clutch plate and vehicle dynamometer testing evaluated launch performance, lock-up times, and durability over nearly 120,000 shifts. Fluid testing showed improved friction durability, faster lock-up times, and good viscosity retention. Component inspections after testing found acceptable wear and corrosion protection. The optimized DCT fluid demonstrated robust performance for automotive applications.

1. OPTIMISING THE WET DCT WITH FLUID
TECHNOLOGY
-FROM TRIBOLOGY TO IN-VEHICLE PERFORMANCE
MICHAEL GAHAGAN-LUBRIZOL LTD, DERBY, UK
JAMES ZHANG-LUBRIZOL, BEIJING,P.R.CHINA
© 2013 The Lubrizol Corporation, all rights reserved.

2. Contents
•
•
•
•
Tribometer testing
Formulation
Clutch plate friction testing
Vehicle dynamometer testing
–
–
–
–
–
Driving cycle
Sensor set-up
Test outputs/results
Fluid results
Transmission rating/inspection
• Conclusions
2
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3. Tribometer testing
Tribometer VSFT disk/rotor configuration
Steel rotor
with
annulus
Plain disk friction material
on steel backing
Test DCT Fluid
Force
3
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4. Tribometer testing
VSFT test rig - detail of test head
Torque cell
Spindle
Test oil reservoir
Heater
4
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Coolant
Pneumatic cylinder

5. Tribometer testing
VSFT mu-v curves
(friction coefficient versus m/s curves)
Positive engagement characteristic
DCTF
5
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Negative engagement characteristic
Comparison

6. Formulation
DCTF – formulation and viscometrics
• Additive Package
–
–
–
–
–
–
–
Friction modifiers
Anti-wear
Copper corrosion inhibitor
Dispersant
Detergent
Seal swell agent
Antioxidant
• Viscosity modifier
• Base Oil
6
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Viscosity:KV 100 °C= 6.9 cSt
BV -40 °C = < 12,000 cP

7. Clutch plate friction testing
High Energy Launch Testing
7
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8. Clutch plate friction testing
Midpoint mu (friction coefficient)
8
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9. Clutch plate friction testing
Clutch lock-up time
9
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10. Clutch plate friction testing
10
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11. Vehicle dynamometer testing
Drive cycle highlights
Phase
Details
Warm-up
Vehicle idled at 0 mph
Accelerator Pedal Position [%]
20
40
Standing Starts
60
80
100
Single-Gear
Downshifts
11
Total Miles
16917
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Downshift
Sequence
4-3-2
5-4-3
6-5-4-3
7-6-5-4-3
7-6-5-4
7-6-5
Skip-Shift
Downshifts
Period
288 hours
Start Speed
[mph]
30
35
40
48
70
85
selected
selected
Cool Down
Cool down cycle
Downshifts Upshifts Launches
70
94
7

12. Vehicle dynamometer testing
Set-up on dynamometer
(1) Blower; (2) Drive Axle and Roller; (3) Fueling Station with Hand Dispenser; (4)
Stationary Axle; (5) Instrumentation and Control Cables
12
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13. Vehicle dynamometer testing
Robot driver
13
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14. Vehicle dynamometer testing
Driving profile
Vehicle Speed [mph]
100
80
60
40
20
0
0
14
5
10
Time [minutes]
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15
20
25

15. Vehicle dynamometer testing
Sensor location
Transmission Sump
Mechatronic
module
Heat exchanger
15
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Mechatronic(case)
Clutch housing

16. Vehicle dynamometer testing
Standing Starts
16
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17. Vehicle dynamometer testing
KPa
Average pressures
17
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18. Vehicle dynamometer testing
Temperature profile
18
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19. Vehicle dynamometer testing
19
Calcium
Copper
Iron
Molybdenum
Phosphorus
Silicon
Sodium
Zinc
Interval
SOT
(Virgin)
SOT
T2-1
T2-2
T2-3
T2-4
T2-5
T2-6
(EOT)
Boron
Elemental analysis (ASTM D5185)
39
41
46
45
47
48
43
226
223
223
221
222
223
218
<1
<1
4
5
6
6
7
<1
1
42
56
75
92
111
<1
<1
<1
<1
<1
<1
<1
540
532
532
529
530
528
530
2
2
14
16
18
19
21
7
7
10
10
11
12
12
<1
1
4
6
9
10
11
46
222
7
121
<1
532
20
11
13
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20. Vehicle dynamometer testing
Viscosity change
ASTM D445
Interval
Viscosity Viscosity
Actual
@100C, @ 40C,
Odometer Test Miles
cSt
cSt
SOT
(Virgin)
23,015
0
6.75
31.96
SOT
23,015
0
6.67
32.10
T2-1
26,015
3000
6.66
31.66
T2-2
29,071
6056
6.64
31.54
T2-3
6.58
31.34
35,015
12000
6.56
31.27
T2-5
T2-6
(EOT)
© 2013 The Lubrizol Corporation, all rights reserved.
9001
T2-4
20
32,016
38,015
15000
6.52
31.09
39,932
16917
6.52
31.11
KRL shear
test rig, 60
hours = 6.50
cSt

21. Vehicle dynamometer testing
Component inspection/rating
21
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22. Vehicle dynamometer testing
Component inspection/rating
22
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23. Vehicle dynamometer testing
23
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24. Conclusions
•
•
•
•
•
Tribometer for fluid selection
Improved friction durability
Faster lock-up times
Good shear stability (viscosity retention)
Severe test
–
–
–
–
–
118,674 shifts, over loaded-high ambient
trouble-free transmission performance
acceptable wear
trace levels of non-ferrous metals
surfaces clean, corrosion protection
• Robust core additive technology for DCT application
24
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25. Thanks for your attention
Working together, achieving great things
When your company and ours combine energies, great things can happen.
You bring ideas, challenges and opportunities. We’ll bring powerful additive and
market expertise, unmatched testing capabilities, integrated global supply and
an independent approach to help you differentiate and succeed.
Contact us
– Name: James Zhang or Michael Gahagan
– E-mail: James.Zhang@Lubrizol.com
– E-mail: Michael.Gahagan@Lubrizol.com
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