Title: Cylinder-pressure-based methods for sensing spark-ignition engine knock

Authors: Jonathan M. Borg, Alex C. Alkidas

Addresses: Research and Development, Hitachi America Ltd., Farmington Hills, MI, USA. ' Department of Mechanical Engineering, Oakland University, Rochester, MI, USA

Abstract: This study used experimental in-cylinder pressure measurements and heat-release analysis to examine the various methods used to quantify the severity of knock and its onset, for a range of engine speeds of 1000 to 4000 rpm. The methods proposed in the literature for assessing the magnitude of knock are grouped into four major categories. It is shown that most have good correlation with the maximum amplitude of the pressure oscillations, which is the most commonly used method. Based on the heat-release analysis, the auto-ignition behaviour of the end-gases was categorised into three types, depending on the location and magnitude of the highest heat release rates due to flame propagation combustion and explosive combustion. At the higher engine speeds, the onset of auto-ignition could be reliably established from the heat-release analysis and it was found to occur about 2 crank angle degrees advanced of the knock onset.

Keywords: knock sensing; knock intensity; knock onset; heat release; autoignition; spark ignition engines; cylinder pressure; flame propagation combustion; explosive combustion; vehicle design.

DOI: 10.1504/IJVD.2007.013678

International Journal of Vehicle Design, 2007 Vol.45 No.1/2, pp.222 - 241

Published online: 11 May 2007 *

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