Patent ID: 6054860
Filing Date: 2000-04-25
Classification: F02P,G01L

Abstract:
A device for detecting knocking in an internal combustion engine comprising:an ionic current detecting unit which applies a voltage across a pair of electrodes installed in a combustion chamber of the internal combustion engine and detects an ionic current flowing between the pair of electrodes when a gas mixture in the combustion chamber is burned;means for masking LC resonance noise superposed on a signal output from the ionic current detecting unit after discharge of a spark plug;a band-pass filtering means for extracting knocking frequency components from a signal output from the LC resonance masking means;means for determining whether knocking has occurred in the internal combustion engine based upon a signal output from the band-pass filtering means; anda buffering device installed between the LC resonance masking means and the band-pass filtering means, the buffering device rejecting a stepwise chance in a signal input to the band-pass filtering means when the LC resonance masking means is reset, wherein the buffering device includes an operational amplifier including an inverting input and an output, an input resistor coupled to the inverting input and a feedback resistor connected between the output of the operational amplifier and the inverting input, and a capacitor connected in parallel with the feedback resistor.