Device for detecting knocking in an internal combustion engine

摘要

A device for detecting knocking in an internal combustion engine capable of preventing accuracy for detecting knocking from being deteriorated by noise when resetting the LC resonance masking unit. An ionic current signal detected by an ionic current detecting unit is supplied to a buffer amplifier 5 via an LC resonance masking unit 31. To a first operational amplifier 51 of the buffer amplifier is connected a capacitor 513 for rejecting noise in parallel with a first feedback resistor 512. A second operational amplifier inverts again the ionic current signal inverted by the first operational amplifier. The buffer amplifier prevents a stepwise change on the input to the band-pass filtering unit when the masking of the LC resonance masking unit is reset, and suppresses a reduction in accuracy for detecting the knocking.