Engine-knock detection method and apparatus

摘要

An amplitude envelope signal is derived from the output of an engine-knock sensor. Either the peak value of the envelope signal or its steepest rate of rise initiates the operation of a delay circuit providing a signal after a delay that is dependent upon the magnitude of the peak value or rate of rise. The envelope signal is also compared with a reference signal responsive to or representing or simulating background noise levels, and a comparison signal is produced when the envelope signal exceeds the reference signal. Engine-knock recognition is determined by the coincidence of the comparison signal and the delayed signal, and may be subjected also to a measurement window criterion which limits the appearance of an engine-knock signal to a particular arc of crankshaft revolution.