Patent ID: 6314724
Filing Date: 2001-11-13
Classification: F02D

Abstract:
An air-fuel ratio controller for an internal combustion engine with a catalytic converter in an exhaust passage, said air-fuel ratio controller comprising:an air-fuel ratio sensor that produces a signal indicative of an air-fuel ratio of an exhaust gas in the exhaust passage on an upstream side of the catalytic converter;an engine sensor that produces a signal indicative of misfiring of the engine; anda control unit operatively coupled to said air-fuel ratio sensor and said engine sensor, wherein said control unitcomputes an estimated quantity of oxygen to be stored in the catalytic converter based on said signal from said air-fuel ratio sensor,determines if the engine is misfiring based on said signal from said engine sensor, andproduces an estimated adjustment value and adjusts an air-fuel ratio of intake air fuel mixture based on said estimated adjustment value such that said estimated quantity of oxygen to be stored substantially coincides with a predetermined target quantity of oxygen to be stored, except when misfiring is determined based on said signal from said engine sensor, in which case a predetermined value is used to control said air-fuel ratio of said intake air-fuel mixture.