Apparatus for controlling air-fuel ratio of internal combustion engine

摘要

The air-fuel ratio of an air-fuel mixture to be combusted in an internal combustion engine 1 is manipulated to converge an output VO2/out of an O2 sensor 6 which is disposed downstream of a catalytic converter 3 to a target value VO2/TARGET depending on an operating state of the internal combustion engine 1, while at the same time a deterioration evaluating parameter is determined from time-series data of the output VO2/out of the O2 sensor 6. The value of the deterioration evaluating parameter is corrected depending on an average value of the output VO2/out of the O2 sensor 6 or the target value VO2/TARGET, and the deteriorated state of the catalytic converter 3 is evaluated based on the corrected value of the deterioration evaluating parameter.