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Open AccessArticle

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

Automotive Powertrain Technologies Laboratory, Empa Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
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Energies 2020, 13(7), 1682; https://doi.org/10.3390/en13071682
Received: 11 February 2020 / Revised: 12 March 2020 / Accepted: 20 March 2020 / Published: 3 April 2020
(This article belongs to the Special Issue Advances in Spark-Ignition Engines)
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. View Full-Text
Keywords: Miller cycles; early intake valve closing; electro hydraulic valve train; energy balance; heat losses Miller cycles; early intake valve closing; electro hydraulic valve train; energy balance; heat losses
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Balmelli, M.; Zsiga, N.; Merotto, L.; Soltic, P. Effect of the Intake Valve Lift and Closing Angle on Part Load Efficiency of a Spark Ignition Engine. Energies 2020, 13, 1682.

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