ME433 Project: Variable Compression Ratio Engine Systems
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ME433 Project: Variable Compression Ratio Engine Systems Anthony Crawford Ph.D., P.E.
description
ME433 Project: Variable Compression Ratio Engine Systems. Anthony Crawford Ph.D., P.E. Compression ratio. Knock Limits Compression Ratio. Ways to mitigate knock Higher octane fuel Sophisticated control system Reduced compression ratio. Theoretical VCR Benefit. - PowerPoint PPT Presentation
Transcript of ME433 Project: Variable Compression Ratio Engine Systems
ME433 Project:Variable Compression Ratio Engine Systems
Anthony CrawfordPh.D., P.E.
Compression ratio
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11 kr
Knock Limits Compression Ratio
• Ways to mitigate knock– Higher octane fuel– Sophisticated control system– Reduced compression ratio
Theoretical VCR Benefit
• Engine Efficiency (Envera 2.2L VCR I4, a 3.6L turbo-DI V6, and a 5.7L V8 )
• Torque/Power Improved at below WOT levels
NmQ
rKT fLV
30112 1 fLV mQ
rKP
3011 1
Various VCR Systems
System Criterion 1 2 3 4 5 6 7 8 9 10Suitability for
Cont. CR Continuous VCR 2-stage VCR
Determination of Actual CR + + + + + + - - - -
Chamber Shape -- ++ ++ ++ ++ ++ ++ ++ ++ ++
Impact on Package - -- -- -- - - ++ + + +
Modification of Production o -- -- -- - - + + + +
Oscillating Mass ++ -- -- ++ ++ -- -- + + --
Friction ++ - - ++ - - o + -- oCosts o - -- -- - - o - - --
++ very low negative impact + low negative impact o moderate impact
- high negative impact -- very high negative impact
• Secondary piston– Changes clearance V
VCR that adjust the clearance volume without modifying the TDC
System Criterion 1 2 3 4 5 6 7 8 9 10
Suitability for Cont. CR Continuous VCR 2-stage VCR
Determination of Actual CR
+ + + + + + - - - -
Chamber Shape
-- ++ ++ ++ ++ ++ ++ ++ ++ ++
Impact on Package
- -- -- -- - - ++ + + +
Modification of Production
o -- -- -- - - + + + +
Oscillating Mass
++ -- -- ++ ++ -- -- + + --
Friction ++ - - ++ - - o + -- o
Costs o - -- -- - - o - - --
++ very low negative impact+ low negative impact
o moderate impact-high negative impact
--- very high negative impact
• Rotation– Moves cylinder up
VCR that adjust the clearance volume without modifying the TDC
System Criterion 1 2 3 4 5 6 7 8 9 10
Suitability for Cont. CR Continuous VCR 2-stage VCR
Determination of Actual CR
+ + + + + + - - - -
Chamber Shape
-- ++ ++ ++ ++ ++ ++ ++ ++ ++
Impact on Package
- -- -- -- - - ++ + + +
Modification of Production
o -- -- -- - - + + + +
Oscillating Mass
++ -- -- ++ ++ -- -- + + --
Friction ++ - - ++ - - o + -- o
Costs o - -- -- - - o - - --
++ very low negative impact+ low negative impact
o moderate impact-high negative impact
--- very high negative impact
• Translation– Moves cylinder up
VCR that adjust the clearance volume without modifying the TDC
System Criterion 1 2 3 4 5 6 7 8 9 10
Suitability for Cont. CR Continuous VCR 2-stage VCR
Determination of Actual CR
+ + + + + + - - - -
Chamber Shape
-- ++ ++ ++ ++ ++ ++ ++ ++ ++
Impact on Package
- -- -- -- - - ++ + + +
Modification of Production
o -- -- -- - - + + + +
Oscillating Mass
++ -- -- ++ ++ -- -- + + --
Friction ++ - - ++ - - o + -- o
Costs o - -- -- - - o - - --
++ very low negative impact+ low negative impact
o moderate impact-high negative impact
--- very high negative impact
VCR that adjust the clearance volume by modifying the TDC
• Linkage– Adjust base pivot or link length to affect TDC
System Criterion 1 2 3 4 5 6 7 8 9 10
Suitability for Cont. CR Continuous VCR 2-stage VCR
Determination of Actual CR
+ + + + + + - - - -
Chamber Shape
-- ++ ++ ++ ++ ++ ++ ++ ++ ++
Impact on Package
- -- -- -- - - ++ + + +
Modification of Production
o -- -- -- - - + + + +
Oscillating Mass
++ -- -- ++ ++ -- -- + + --
Friction ++ - - ++ - - o + -- o
Costs o - -- -- - - o - - --
++ very low negative impact+ low negative impact
o moderate impact-high negative impact
--- very high negative impact
VCR that adjust the clearance volume by modifying the TDC
• Rocking– Movement on one side generates opp. movement in piston
System Criterion 1 2 3 4 5 6 7 8 9 10
Suitability for Cont. CR Continuous VCR 2-stage VCR
Determination of Actual CR + + - + + + - - - -
Chamber Shape -- ++ ++ ++ ++ ++ ++ ++ ++ ++
Impact on Package - -- -- -- - - ++ + + +
Modification of Production o -- -- -- - - + + + +
Oscillating Mass ++ -- -- ++ ++ -- -- + + --
Friction ++ - - ++ - - o + -- oCosts o - -- -- - - o - - --
++ very low negative impact+ low negative impact
o moderate impact-high negative impact
--- very high negative impact
VCR that adjust the clearance volume by modifying the TDC
• Elastic component– Elastic components
compress at higher pressures thus reducing clearance volume and reducing compression ratio at higher loads
VCR that adjust the clearance volume by modifying the TDC
• Eccentric pivots– Effectively adjusts
link lengths System Criterion 1 2 3 4 5 6 7 8 9 10
Suitability for Cont. CR Continuous VCR 2-stage VCR
Determination of Actual CR + + - + + + - - - -
Chamber Shape -- ++ ++ ++ ++ ++ ++ ++ ++ ++
Impact on Package - -- -- -- - - ++ + + +
Modification of Production o -- -- -- - - + + + +
Oscillating Mass ++ -- -- ++ ++ -- -- + + --
Friction ++ - - ++ - - o + -- oCosts o - -- -- - - o - - --
++ very low negative impact+ low negative impact
o moderate impact-high negative impact
--- very high negative impact
Conclusions
• VCR systems have the promise to increase:– engine efficiency/power/torque– operate with multiple cycles– adjust to accommodate knock limitations of
various fuels.• Multiple VCR systems each have their own
advantages and disadvantages with regard to:– effectiveness– complexity– ability to be integrated into current engines
Key References• Pischinger, S., et. al. “Two-stage Variable Compression Ratio
with Eccentric Piston Pin,” MTZ Worldwide Edition, 2009-02.
• Mendler, C., “Envera Variable Compression Ration Engine,” US DOE report DE-FC26-05NT42484, March 15, 2011.
• Aina, T., et. al. “Influence of compression ratio on the performance characteristics of a spark ignition engine,” Advances in Applied Science Research, 3 (4): 1915-1922, 2012.
