| 摘要 |
PROBLEM TO BE SOLVED: To detect only ion current components generated by combustion at the time of combustion even when a leak current is generated. SOLUTION: The mifire detecting device is provided with an ion current detecting means 16 for detecting the ion current generated in a cylinder immediately after combustion, a leak detecting means 21 for detecting a leak current generated between electrodes of an ignition plug, a first waveform shaping means 20 for pulse-shaping the detected ion current by comparing the detected ion current to a first threshold value for judging the ion current, which is set based on a level at the rise time of the ion current superposed on the leak current, a second waveform shaping means 18 for pulse shaping the detected ion current by comparing the detected ion current to a second threshold value fixed to a lower value than the first threshold value, and a selecting means 22 for selectively outputting the pulse shaped by the first waveform shaping means 20 as a combustion pulse when the current is detected, and for selectively outputting the pulse shaped by the second waveform shaping means 18 as a combustion pulse when no leak current is detected.
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