Knock determining device and method for internal combustion engine

摘要

A band pass filter processing extracts the vibration component (frequency component) of the 1st to the 4th order frequency band from the output of the knock sensor. A primary frequency band is established as the frequency band containing the fundamental frequency (primary resonance frequency) which is the lowest frequency of the knocking vibration frequencies. The 2nd to the 4th order frequency band is established as the frequency band containing the 2nd to the 4th order resonance frequency. Based on the vibration strength of the primary frequency component, the comparison result between the composite vibration waveform which compounded the 1st to the 4th order frequency component and the ideal knock waveform, and the vibration strength of the summation of the 1st to the 4th order frequency component, the noise and knocking are distinguished from each other with sufficient accuracy.