Dearborn, October 16th, 2012
Two-Stage Variable Compression Ratio (VCR) System to Increase Efficiency in Gasoline Powertrains
DEER Conference 2012
D. Tomazic, H. Kleeberg, S. Bowyer, FEV Inc.
J. Dohmen, K. Wittek, B. Haake, FEV GmbH
© by FEV – all rights reserved. Confidential – no passing on to third parties
Content
Introduction and motivation
Layout of FEV’s two-stage VCR system
CO2 reduction potential
Combination with future technologies
Summary and conclusion
12-04-27_WMS_2012_VCR.pptx K. Wittek 2
© by FEV – all rights reserved. Confidential – no passing on to third parties
Introduction and Motivation Principle Influence of Compression Ratio on Fuel Consumption
3
Compression ratio (CR) [-]
BSF
C [%
]
high
100
low
CRbase
2000 rpm / WOT 2000 rpm / BMEP = 2 bar
14 8
VCR
12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
Introduction and Motivation Classification of VCR Systems
Variable piston TDC position
εmin
εmax
Unconventional cranktrains
Variable distance head - crankshaft
Variable kinematic lengths
4 12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
Content
Introduction and motivation
Layout of FEV’s two-stage VCR system
CO2 reduction potential
Combination with future technologies
Summary and conclusion
5 12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
Layout of FEV’s Two-stage VCR System Working Principle: Conrod
6 6 12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
Layout of FEV’s Two-stage VCR System Working Principle: Mechanical Actuation
7
Cam disc carrier
View from top
horizontal movement
valve body
functional surface
12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
Layout of FEV’s Two-stage VCR System Transition Time During Load Step
8
actual CR ideal CR
high
low -0.2 0.0 0.2 0.4 0.6 0.8 1.0
2500
2000
1500
1000
500
0
CR
[-]
Acce
lera
tor
Peda
l [-]
Manifold pressure [m
bar]
Time [s]
Full Load
Part Load
n = 2000 rpm Oil temp. = 90°C
12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
Layout of FEV’s Two-stage VCR System Influence of Oil Temperature
9
0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 0
high
low
CR
[-]
Time [s]
n = 2000 rpm BMEP = 8 bar Oil temp.:
0°C 90°C
CR ‘low high‘ CR ‘high low‘ �̇� = 𝛼𝐷 ⋅ 𝐴 ⋅
2Δ𝑝𝜌
12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
Content
Introduction and motivation
Layout of FEV’s two-stage VCR system
CO2 reduction potential
Combination with future technologies
Summary and conclusion
10 12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
50 kph, 3rd gear
70 kph,5th gear
120 kph, 6th gear
50 kph, 3rd gear
70 kph,5th gear
120 kph, 6th gear
BM
EP [b
ar]
0
5
10
15
20
25
Engine Speed [rpm]1000 2000 3000 4000 5000
1312
1110
9
8
14
ε =
Continuous VCR
CO2 Reduction Potential Compression Ratio Maps Continuous VCR vs. Two-stage VCR
11
Engine Speed [rpm]1000 2000 3000 4000 5000
131211109876543210
Fuel Sharein NEDC [%]
VCR shift line
ε = 12
ε = 8
Two-stage VCR CR 8/12
12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
CO2 Reduction Potential Influence of CR-stages on the VCR Shift Line and BMEP at WOT
12
50 kph, 3rd gear70 kph, 5th gear
BM
EP [b
ar]
0
5
10
15
20
25
Engine Speed [rpm]1000 2000 3000 4000 5000
CR 9/14 CR 8/12
120 kph, 6th gear
VCR shift lines 8 ↔ 12
9 ↔ 14
12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
Layouts of CR stages
8/12 8/13 8/14 9/14 10/14
CO2 Reduction Potential Simulation Boundaries - Europe
Vehicle IWC 1372 kg
6-speed MT
2.0 L TC GDI, RON 95
Pmax = 180 kW (const.)
Base CR 9,6 (BMEPmax = 22 bar)
BMEPmax (function of CRlow)
13 12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
CO2 Reduction Potential Simulation Results - Europe
14
1 0 0
1 1 0
1 2 0
1 3 0
1 4 0
1 5 0
1 6 0
CO
2 Em
issi
on [g
/km
]
Base fixed CR
NEDC
-5.6% -5.9% -5.7% -5.8% -5.5%
WLTP
-5.1% -5.2% -4.5% -5.0% -4.3%
CR = 9.6 CR = 8/12 CR = 8/13 CR = 8/14 CR = 9/14 CR = 10/14
12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
CO2 Reduction Potential Simulation Results - USA
15 12-04-27_WMS_2012_VCR.pptx K. Wittek
FTP 75Full size sedan
Baseline CR = 9/12 CR = 9/13 CR = 9/14 CR = 10/12 CR = 10/13 CR = 10/14
CO
2 E
mis
sion
s [g
/km
]
170
175
180
185
190
195
200 Premium Fuel Regular Fuel
-4.8%-3.9%-2.8%
-4.5% -5.3% -6.0% -4.8% -6.5%-5.6%
-2.8% -4.0% -4.8%
CR
= 1
0.5
CR
= 1
0
Vehicle: 1670 kg (3682 lbs) Engine: 2.0L GTDI w/ P = 180 kW; RON 95 Transmission: 7 Speed wet DCT
© by FEV – all rights reserved. Confidential – no passing on to third parties
CO2 Reduction Potential Simulation Results - USA
16 12-04-27_WMS_2012_VCR.pptx K. Wittek
Fuel share in FTP75 [%]
BM
EP [b
ar]
0
2
4
6
8
10
12
14
16
18
20
22
24
Engine Speed [rpm]1000 2000 3000 4000 5000 6000
Turbocharged DI 2.0L CR=10/14
CR = 14
CR = 10
FTP75 - Full Size Sedan w/ Premium Fuel
6
5
4
3
2
1
0
© by FEV – all rights reserved. Confidential – no passing on to third parties
CO2 Reduction Potential Simulation Results - USA
17 12-04-27_WMS_2012_VCR.pptx K. Wittek
BM
EP [b
ar]
0
2
4
6
8
10
12
14
16
18
20
22
24
Engine Speed [rpm]1000 2000 3000 4000 5000 6000
Turbocharged DI 2.0L CR=10/14
CR = 14
CR = 10
US06 - Full Size Sedan w/ Premium Fuel
8
7
6
5
4
3
2
1
0.8
0.5
0.3
0
Fuel share in US06 [%]
© by FEV – all rights reserved. Confidential – no passing on to third parties
Content
Introduction and motivation
Layout of FEV’s two-stage VCR system
CO2 reduction potential
Combination with future technologies
Summary and conclusion
18 12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
Combination with Future Technologies
Alternative fuels
Gasoline controlled auto ignition (GCAI)
19
‘Extreme downsizing’
12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
1 0 0
1 1 0
1 2 0
1 3 0
1 4 0
1 5 0
1 6 0
CO
2 Em
issi
on [g
/km
] Combination with Future Technologies Two-stage VCR Combined with ‘Extreme’ Downsizing
20
Inertia weight class: 1372 kg 6-speed MT, gear ratios adapted Pmax = 180 kW (const.)
Base fixed CR
NEDC WLTP
-5.9%
-5.2%
2.0l, CR = 9.6 2.0l, CR = 8/13
‘Extreme Downsizing‘ Fixed CR
1.5l, CR = 8.2
-7.1%
-6.5%
1.5l, CR = 8/12
12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
Combination with Future Technologies Two-stage VCR Combined with GCAI - Gasoline Controlled Auto Ignition
21
Base vehicle: 1372 kg, 1.8L -4% CO2 in NEDC
Fixed CR = 9.8
GCAI operation area
Load too low for GCAI
Two-stage VCR CR = 9.8/13 -12% CO2 in NEDC
Load too high for GCAI
12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
Combination with Future Technologies Two-stage VCR Combined with Alternative Fuels
22
BM
EP [b
ar]
0
5
10
15
20
25
Engine Speed [rpm]1000 2000 3000 4000 5000
2.0l, TC, Two-Stage VCR 8/12 (optimized for RON 95)
RON 95
RON 98
RON 91
Exx
12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
Two-stage VCR System Summary and Conclusions
VCR can help to resolve the conflict between part load and full load CR layout especially for boosted downsized gasoline engines
The presented two-stage VCR system is based on a variable length conrod with eccentric piston pin suspension and can be adapted to existing engines with moderate effort
The transition time can be adjusted according to the thermodynamic requirements
CO2 reduction potential for moderate downsized GDI engines 5 – 6% Increased benefit for extreme downsized GDI engines of up to 7% in NEDC Operating area of GCAI technology can be significantly enlarged resulting in
up to 12% CO2 reduction in combination with two-stage VCR in NEDC The higher knock resistance of alternative (flex) fuels can be used via
adaptation of the VCR shift line in the map
23 12-04-27_WMS_2012_VCR.pptx K. Wittek
© by FEV – all rights reserved. Confidential – no passing on to third parties
DEER Conference 2012 Two-stage VCR system
Thank you for your kind attention!
24 12-04-27_WMS_2012_VCR.pptx K. Wittek