Abstract
In order to detect the combustion quality in a production SI engine, the ion sensor of gasket type was used. The relationship between the ion current and the rate of heat release was discussed. Under the operating conditions that the equivalence ratio, intake pressure and engine speed were varied, the averaged timing of rise of ion current for gasket ion sensor corresponds with the timing of 50% MFB. The ion current fraction accumulated, ICFA, was defined from the summation waveforms of ion current for gasket ion sensor. It was found that the timing of 5% ICFA corresponds with that of 50% MFB and the timing of 50% ICFA corresponds with that of 90% MFB. Therefore, the circular type gasket ion sensor can obtain the information of rate of heat release for individual cycle.
