Patent ID: 7474956

Claim:
An air-fuel ratio control system of an internal combustion engine comprising: an exhaust purification catalyst having an oxygen storage capacity arranged in an exhaust passage of the internal combustion engine, storing oxygen in the exhaust when a concentration of oxygen in inflowing exhaust is in excess, and releasing stored oxygen when the concentration of oxygen in the exhaust is insufficient, an intake air amount detecting means for detecting an intake air amount of said internal combustion engine, a linear air-fuel ratio sensor arranged at an upstream side of said exhaust purification catalyst and having an output characteristic substantially proportional to an air-fuel ratio of the exhaust, an O 2 sensor arranged at a downstream side of said exhaust purification catalyst and sensing if an air-fuel ratio of the exhaust is rich or lean, a target air-fuel ratio controlling means for performing feedback control of a target air-fuel ratio of exhaust flowing into said exhaust purification catalyst based on detection information from said intake air amount detecting means and said O 2 sensor, and a fuel injection amount controlling means for performing feedback control of the fuel injection amount based on output information of said linear air-fuel ratio sensor so as to control said air-fuel ratio of the exhaust flowing into the exhaust purification catalyst to said target air-fuel ratio, said air-fuel ratio control system of an internal combustion engine characterized in that said target air-fuel ratio controlling means performs feedback control of said target air-fuel ratio so that even when said intake air amount changes, a correction amount per unit time of an oxygen storage amount of said exhaust purification catalyst is made constant.