Patent ID: 6698186
Filing Date: 2004-03-02
Classification: F01N,F02D,Y02T

Abstract:
An apparatus for controlling the air-fuel ratio of an internal combustion engine, comprising:an exhaust gas sensor disposed downstream of a catalytic converter which is disposed in an exhaust passage of an internal combustion engine, for detecting the concentration of a particular component of a exhaust gas emitted from the internal combustion engine and having passed through the catalytic converter; air-fuel ratio manipulated variable generating means for sequentially generating a manipulated variable to determine the air-fuel ratio of the exhaust gas entering said catalytic converter to converge an output of said exhaust gas sensor to a predetermined target value; air-fuel ratio manipulating means for manipulating the air-fuel ratio of an air-fuel mixture to be combusted in said internal combustion engine depending on said manipulated variable; and deteriorated state evaluating means for sequentially determining the value of a deterioration evaluating linear function from time-series data of the output of said exhaust gas sensor, said deterioration evaluating linear function having variable components represented by said time-series data of the output of said exhaust gas sensor, and evaluating a deteriorated state of said catalytic converter based on the determined value of the deterioration evaluating linear function, while the air-fuel ratio of the air-fuel mixture is being manipulated by said air-fuel ratio manipulating means.