Effect of the Intake Valve Lift and Closing Angle on Part Load Efficiency of a Spark Ignition Engine

Michelangelo Balmelli, Norbert Zsiga, Laura Merotto and Patrik Soltic
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Michelangelo Balmelli: Automotive Powertrain Technologies Laboratory, Empa Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
Norbert Zsiga: Automotive Powertrain Technologies Laboratory, Empa Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
Laura Merotto: Automotive Powertrain Technologies Laboratory, Empa Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
Patrik Soltic: Automotive Powertrain Technologies Laboratory, Empa Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland

Energies, 2020, vol. 13, issue 7, 1-16

Abstract: This study provides an experimental evaluation of the effectiveness of Miller cycles with various combinations of lift and intake valve closing angle for a passenger car engine with premixed combustion in naturally aspirated operation. A fully variable electro-hydraulic valve train provided different valve lift profiles. Six load points, from 1.5 up to 5 bar brake mean effective pressure at a constant engine speed of 2000 min −1 , were tested with 6 different intake valve lift/intake valve closing angle combinations. The intake valve closing angle was always set before bottom dead center to achieve the desired load with unthrottled operations. Experimental comparison with throttled operation outlines an indicated efficiency increase of up to 10% using high intake lift with early valve closing angle. Furthermore, this analysis outlines the influences that early intake valve closing angle has on fuel energy disposition. Longer combustion duration occurs using early intake valve closing angle because of turbulence dissipation effects, leading to slight reductions in the heat-to-work efficiency. However, overall pressure and temperature levels decrease and consequently heat losses and losses due to incomplete combustion decrease as well. Overall, we found that combustion deterioration is compensated/mitigated by the reduction of the heat losses so that reductions of pumping losses using early intake valve closing can be fully exploited to increase the engine’s efficiency.

Keywords: Miller cycles; early intake valve closing; electro hydraulic valve train; energy balance; heat losses (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (6)

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