ME 433 Project Variable Compression Ratio Engine Systems

ME 433 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 • Engine Efficiency (Envera 2. 2 L VCR I 4, a 3. 6 L turbo-DI V 6, and a 5. 7 L V 8 ) • Torque/Power Improved at below WOT levels

Various VCR Systems System Criterion Suitability for Cont. CR Determination of Actual CR Chamber Shape Impact on Package Modification of Production Oscillating Mass Friction Costs 1 2 3 4 5 6 7 Continuous VCR 8 9 10 2 -stage VCR + + + - - -- ++ ++ ++ - -- - - ++ + o -- -- -- - - + + ++ -- -- ++ ++ -- -- + + -- ++ o - -- ++ -- - - o o + - -- o -- ++ very low negative impact - high negative impact + low negative impact o moderate impact -- very high negative impact

VCR that adjust the clearance volume without modifying the TDC • Secondary piston – Changes clearance V Criterion. System Suitability for Cont. CR Determination of Actual CR Chamber Shape Impact on Package Modification of Production Oscillating Mass Friction Costs 1 2 3 4 5 6 7 Continuous VCR 8 9 10 2 -stage VCR + + + - - -- ++ ++ ++ - -- - - ++ + o -- -- -- - - + + ++ -- -- ++ ++ -- -- + + -- ++ - - o + -- o 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 without modifying the TDC • Rotation – Moves cylinder up System Criterion Suitability for Cont. CR Determination of Actual CR Chamber Shape Impact on Package Modification of Production Oscillating Mass Friction Costs 1 2 3 4 5 6 7 Continuous VCR 8 9 10 2 -stage VCR + + + - - -- ++ ++ ++ - -- - - ++ + o -- -- -- - - + + ++ -- -- ++ ++ -- -- + + -- ++ - - o + -- o 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 without modifying the TDC • Translation – Moves cylinder up System Criterion Suitability for Cont. CR Determination of Actual CR Chamber Shape Impact on Package Modification of Production Oscillating Mass Friction Costs 1 2 3 4 5 6 7 Continuous VCR 8 9 10 2 -stage VCR + + + - - -- ++ ++ ++ - -- - - ++ + o -- -- -- - - + + ++ -- -- ++ ++ -- -- + + -- ++ - - o + -- o 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 Criterion. System for link length to affect TDCSuitability Cont. CR Determination of Actual CR Chamber Shape Impact on Package Modification of Production Oscillating Mass Friction Costs 1 2 3 4 5 6 7 Continuous VCR 8 9 10 2 -stage VCR + + + - - -- ++ ++ ++ - -- - - ++ + o -- -- -- - - + + ++ -- -- ++ ++ -- -- + + -- ++ - - o + -- o 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 Suitability for Cont. CR Determination of Actual CR Chamber Shape Impact on Package Modification of Production Oscillating Mass Friction Costs 1 2 3 4 5 6 7 Continuous VCR 8 9 10 2 -stage VCR + + - + + + - - -- ++ ++ ++ - -- - - ++ + o -- -- -- - - + + ++ -- -- ++ ++ -- -- + + -- ++ o - -- ++ -- - - o 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 Suitability for Cont. CR Determination of Actual CR Chamber Shape Impact on Package Modification of Production Oscillating Mass Friction Costs 1 2 3 4 5 6 7 Continuous VCR 8 9 10 2 -stage VCR + + - + + + - - -- ++ ++ ++ - -- - - ++ + o -- -- -- - - + + ++ -- -- ++ ++ -- -- + + -- ++ o - -- ++ -- - - o 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-FC 26 -05 NT 42484, 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): 19151922, 2012.