VT2+: Further improving the fuel economy of the VT2...
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Transcript of VT2+: Further improving the fuel economy of the VT2...
VT2+: Further improving the fuel
economy of the VT2 transmission
Gert-Jan Vogelaar
Punch Powertrain
21/03/2011 CVT2010 2
Introduction
• VT2 in the market
• Project approach
• Transmission losses
• Flexibility and range
• Idle stop and idle speed
• Summary of improvements
• Conclusions
21/03/2011 CVT2010 3
Current VT2 Applications
21/03/2011 CVT2010 4
Fuel consumption comparison
-6,0%
-4,0%
-2,0%
0,0%
2,0%
4,0%
6,0%
8,0%
2008 2009 2010 2011 2012 2013
DCT
AMT
VT2 Applications
Trend VT2
• VT2 applications keep on achieving better fuel economy
• From 2011, as good as Manual Transmission
• VT2 gets within range of DCTs and AMTs
21/03/2011 CVT2010 5
Project approach
• Identify relevant working areas
• Identify contribution of different losses
• Attack the most contributing losses
• Identify limiting factors on flexibility and range
• Select and improve critical components
21/03/2011 CVT2010 6
Transmission losses
• Relevant areas:
– Driving in Overdrive
– Losses at standstill
• Only these areas are investigated
21/03/2011 CVT2010 7
Losses in OD
Losses in Overdrive
variator
48%
pump
17%
drag R clutch
2%
drag D clutch
0%
pre-tension
bearings
4%
bearings/gears
1%
other
28%
Losses in OD reduced by 19%
variator
34%
Improvement
due to
improved
clamping
control
19%
drag D clutch
0%
drag R clutch
2%
pump
12%
pretention
bearings
4%
bearings/gears
1%
other
28%
• Main losses in Overdrive caused by pump and variator
• 19% reduction via improved clamping control
• Corresponds to approximately 1.5% on NEDC cycle
21/03/2011 CVT2010 8
Losses at standstillLosses at standstill in D
drag R clutch
2%
other
16%
variator
0%
drag D clutch
69%
pump
13%
pretention
bearings
0%
bearings/
gears
0%
Losses at standstill
reduced by 67%
pretention
bearings
0%
bearings/gears
0%
pump
13%
drag D clutch
2%
variator
0% drag R clutch
2%
other
16%
Improvement
due to improved
clutch control
67%
• Drag in D clutch by far the biggest cause of losses
• Reduction of 67% realised via improved clutch control
• Corresponds to 1-1.5% on NEDC cycle
21/03/2011 CVT2010 9
Flexibility and range
• Approach: Try to lower engine speed whenever possible
• Via optimising variogram in software
• Via improving oil balance
-6,0%
-4,0%
-2,0%
0,0%
2,0%
4,0%
6,0%
8,0%
2008 2009 2010 2011 2012 2013
Improvement via:
Improved clutch controlImproved variogram
Improved warm up cycle
21/03/2011 CVT2010 10
Improving oil balance
Engine speed
Oil
flo
ws
Oil supply
Available for shifting
Consumers
Required for shifting
Minimum engine
speed out of
Low ratio
Engine speed
Oil f
low
s
Oil supply
Available for shifting
Old available flow for shifting
Required for shifting
Improvement in
minimum engine
speed out of Low
• Bigger oil pump improves supply, but increases transmission losses
• Improved pressure regulators reduce the oil consumption
• Via both measures animprovement of 1.9% can be
realised (measured)
Engine speed
Oil f
low
s
Oil supply old
Available for shifting
Old available flow for shifting
Required for shifting
Improved oil supply
Improvement in
minimum engine
speed out of Low
21/03/2011 CVT2010 11
Idle stop and idle speed
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Total driving Overall total Total stand still
1st cycle
2nd cycle
3rd cycle
4th cycle
• VT2 includes idle stop capability, without mechanicaladaptation
• Contribution of fuel consumption during idle measuredbetween 8-14%, but what part can effectively be reduced?
• In case during first two ECE cycles, idle stop is not yetapplied, approximately 6% improvement can be realised
21/03/2011 CVT2010 12
Summary of improvements
Option availableNow-9.9%-6.0%*Idle stop
Improvement estimated,
hardware testing started.
2012-5.3%-1.2%Idle speed
Improvement measured.
Hardware testing started.
2012-4.1%-1.9%Oil consumption
Test result. Validation on-going2011-2.3%-1.2%New oil
Simulation result,
SW under development
2011-1.1%-1.5%Clamping control
Improvement measured,
SW validated
2011+0.4%-4.1%Clutch control, variogram,
warm up cycle
Production2010+4.7%-Baseline
StatusByFE vs. MT
(cumm)
FE vs.
VT2
Improvement
* Maximum value. Value will reduce if idle speed is reduced, but the sum of idle stop and idle speed
improvements will not be lower than 6%.
21/03/2011 CVT2010 13
Future improvements on VT2
-10,0%
-8,0%
-6,0%
-4,0%
-2,0%
0,0%
2,0%
4,0%
6,0%
8,0%
2008 2009 2010 2011 2012 2013
Without idle stop
Including idle stop
Historical trend
DCT
AMT
21/03/2011 CVT2010 14
Conclusions
• Via a simple and straightforward approach, the weakareas in the VT2 could be determined and improved
• From 2011, VT2 can deliver similar fuel economy as the MT of the same vehicle
• Additional planned SW and HW improvements will givethe VT2 a benefit over MT of 4.4% in the NEDC by 2012
• From 2011, VT2 can be 5% better than an MT in the NEDC if the idle stop option will be used
• From 2012 VT2 can be 9% better than an MT in the NEDC if the idle stop option will be used
• With these improvements, VT2 can match or do betterthan the best AMTs and DCTs
Thank you for your attention
21/03/2011 CVT2010 16
Further outlook
-8.5%-2.0%Hydraulics, controls
-6.7%-1.5%Curved pulleys / chain
-13.0%-6.0%*Idle stop
-5.3%-1.2%Idle speed
-4.1%-1.9%Oil consumption
-2.3%-1.2%New oil
-1.1%-1.5%Clamping control
+0.4%-4.1%Clutch control, variogram, warm up cycle
+4.7%-Baseline
FE vs. MT (cumm)FE vs. VT2Improvement
• Hybridisation: See presentation by P. Debal
* Maximum value. Value will reduce if idle speed is reduced, but the sum of idle stop and idle speed
improvements will not be lower than 6%.