KNOCKING DETECTION SYSTEM FOR ENGINE

摘要

PURPOSE:To enable an accurate detection of knocking of an engine by performing a Fourier transformation processing and an arithmetic average processing of an output of a knocking sensor. CONSTITUTION:An output signal of a sensor S1 is inputted into a microcomputer muCOM through an A/D conversion circuit. A knocking detection signal inputted into the computer muCOM is subjected to a Fourier transform processing and then, an arithmetic average processing. In other words, the addition of the results of the Fourier transformation allows cancellation of background noises by addition of the positive pole of background noises generating at rondom and the negative pole noises as shown by the background noise N' while the elongation of a knocking signal S generating in only one polarity by addition thereof as shown by the knocking signal S'. The use of a specified judgement level V enables the identification of the presence of knocking signals accurately. In this manner, the accurate detection of engine knockings can be performed.