Patent Document ID: 8126635
Application ID: 12664766
Patent Status: 1

Claim One:
1. An air-fuel ratio control apparatus for an internal combustion engine that includes a lift amount change mechanism for changing a lift amount of intake valves and a sensor for outputting a signal corresponding to a concentration of oxygen in exhaust gas and sets a fuel injection amount command value through a feedback control using a correction amount calculated based on an output value of the sensor, the air-fuel ratio control apparatus comprising: a learning unit that learns amounts of divergence of the correction amount from a reference value thereof as divergence amount learning values respectively as to a plurality of set lift amount regions; a correction unit that calculates a divergence amount correction value based on the respective divergence amount learning values learned by the learning unit and the lift amount of the intake valves and correcting the fuel injection amount command value in an increasing/decreasing manner with the calculated divergence amount correction value; wherein a reflection unit that reflects a learning result of the divergence amount learning value of a specific one of the plurality of the set lift amount regions on the divergence amount learning value of another one of the lift amount regions if there is a history indicating that the divergence amount learning value of the specific one of the lift amount regions has been learned and there is no history indicating that the divergence amount learning value of that another one of the lift amount regions has been learned, wherein the reflection unit appropriates the divergence amount learning value of the specific one of the lift amount regions as the divergence amount learning value of that another one of the lift amount regions if a lift amount in another one of the lift amount regions is smaller than the lift amount in the specific one of the lift amount region.