KNOCK CONTROL SYSTEM FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To determine the presence or absence of knocks precisely in consideration of a variation in the knock determination level caused by a variation in the background noise level that is superposed on a knock signal waveform. SOLUTION: A knock sensor 10 detects knock strength values, which are accumulated into the total whose half point is used as a median and from which a value in correspondence with the standard deviation thereof is computed. The background noise(BGN) level that is calculated from the standard- deviation-correspondent value is added to or subtracted from the knock strength values into a value in correspondence with a standard deviation for knock detection. The knock strength values are compared with a knock determination level prepared from the median and the knock-detection-standard-deviation- correspondent value against any influence by a variation in the BGN level, which comparison determines the presence or absence of knocks. The procedures make a precise determination of the presence or absence of knocks from the knock strength values, and permit appropriate control of the operating conditions of an internal-combustion engine.