Detection of Combustion Quality in a Production SI Engine Using Ion Sensor

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 has been discussed. Under varying equivalence ratio, intake pressure and engine speeds, the averaged start and peak timings of the ion current for 8 electrodes correspond to timings of 50% MFB and 90% MFB respectively, are also discussed. The waveforms accumulated for all signals of the 8 electrodes are discussed as being analogues to the waveform of a ring ion sensor. Coincidentally, the cycle resolved ion current waveforms accumulated from the 8 electrodes is seen to vary with the rate of heat release. The ion current fraction accumulated (ICFA), has been defined using the summation waveforms of ion current from a 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 ring ion sensor can obtain the information of the rate of heat release for individual cycles in a production SI engine.