Patent ID: 6418785
Filing Date: 2002-07-16
Classification: F02D,F02P,G01M

Abstract:
A misfire detecting apparatus for an internal combustion engine for detecting combustion of an air/fuel mixture or occurrence of misfire event within an engine cylinder of an internal combustion engine on the basis of an ion current which makes appearance upon combustion of the air/fuel mixture, comprising:ion current detecting means for detecting an ion current which depends on an amount of ions generated within said engine cylinder immediately after combustion of the air/fuel mixture within said engine cylinder; first waveform shaping means for shaping the ion current as detected into a pulse signal indicating combustion/misfire event by comparing with a first threshold value for deciding occurrence of the ion current, said first threshold value being set on the basis of a bottom-hold value of said ion current; and means for outputting said pulse signal as a combustion pulse signal indicating either combustion of the air/fuel mixture or occurrence of misfire event.