Abstract
In order to investigate the relationship between ion current and combustion characteristics, an ion current probe utilizing conventional spark plug was applied to gasoline HCCI (Homogeneous Charge Compression Ignition) combustion with hot residual gas. The ion current signals from an ion current probe and in-cylinder pressure were measured simultaneously. The ion current signal of the single cycle of the HCCI combustion had almost one peak. There were slightly differences of the start and peak timing of ion currents at two probe locations in the early stage of reaction, and the differences in both probes was almost zero in the late stage of reaction. Under the homogeneous gas composition, it seems that similar signals of the ion current will be detected even if the ion current signals were detected locally. The characteristics of ion current in whole reaction may be able to conjecture with considering the characteristics of local ion current under homogeneous gas composition. It was found that there is high correlation between the timing of the ion current and the timing of the rate of heat release in spite of various engine conditions.
