| 摘要 |
PROBLEM TO BE SOLVED: To further increase accuracy of knocking determination in reference to an ion current.SOLUTION: An ion current signal obtained by measurement 51 via a circuit for ion current detection is filtered by a band pass filter 52 for passing frequency components of noises, so as to acquire a time point where the filtered signal has a maximum or minimum value. A certain period of time from the time point is defined as a section which may contain noise. The ion current signal obtained by the measurement 51 via the circuit is processed by a band pass filter 53 for passing frequency components of a signal generated due to knocking, and a signal in the period of the filtered signal is obtained by subtraction 54 and 55. Determination 56 and 57 are made as to the presence of knocking on the basis of the attenuated signal. |
