Patent ID: 7222482

Claim:
An air-fuel ratio control apparatus of an internal combustion engine comprising: an exhaust gas purifying catalyst disposed in an exhaust passage of the internal combustion engine; fuel cutting means for cutting fuel to be supplied to the internal combustion engine at the time of deceleration of the internal combustion engine; and catalyst degradation suppressing means for suppressing degradation of the exhaust gas purifying catalyst by prohibiting operation of the fuel cutting means when it is determined that the degradation of the exhaust gas purifying catalyst advances, wherein the catalyst degradation suppressing means sets an operation permitting period, during which the operation of the fuel cutting means is permitted after completion of a fuel quantity increasing operation of the internal combustion engine; and the catalyst degradation suppressing means determines a completion timing of the operation permitting period based on an integration quantity of intake air taken into the internal combustion engine after the completion of the fuel quantity increasing operation.