| 摘要 |
PROBLEM TO BE SOLVED: To provide a combustion state determination device which can exactly determine a combustion state of an internal combustion engine even if a leak current flowing between a center electrode and a side electrode is generated, from ion current due to carbon deposited on an ignition plug.SOLUTION: An ion current waveform area in a combustion state determination zone of an ion current is calculated, an inclination of the leak current of the ignition plug is estimated from smoldering resistance generated at the ignition plug, a leak current area in the combustion state determination zone is calculated, a true ion current obtained by subtracting a leak current area from the ion current waveform area is calculated, a knock integrated value is calculated from the ion current detected by an ion current detection circuit, it is determined that there occurs a knock in the internal combustion engine when a coordinate composed of the knock integrated value and a true ion current waveform area calculated from the true ion current is lager than a knock threshold, and thereby the combustion state is determined from an exact true ion current value obtained from the smoldering resistance even if the leak current flowing between the center electrode and the side electrode is generated due to the carbon deposited on the ignition plug. |
