Patent ID: 8302571

Claim:
An air-fuel ratio control device of an internal combustion engine, the engine including a variable valve lift mechanism, which changes the lift amount of an intake valve, and a sensor that outputs a signal corresponding to the oxygen concentration in exhaust gas, wherein, when an execution condition is not met after operation of the engine has been started, the control device sets a fuel injection amount command value through prediction control based on the operating condition of the engine, and when the execution condition is met, the control device sets the fuel injection amount command value through feedback control using a correction amount computed based on the output value of the sensor, the control device comprising: a learning section, wherein, when the execution condition is met, the learning section learns, as a deviation amount learned value, a constant deviation amount between the correction amount and its reference value in different manners between a case in which the lift amount is in a first lift amount region used only when the execution condition is not met and a case in which the lift amount is in a second lift amount region used only when the execution condition is met, the learning section computes and stores the relationship between the deviation amount and the lift amount based on the deviation amount learned value; a correction section that computes a deviation amount correction value from the stored relationship and based on the lift amount, and corrects the fuel injection amount command value using the deviation amount correction value; and an inhibiting section, wherein, when there is no record of completing learning of the deviation amount when the lift amount is in the first lift amount region, the inhibiting section inhibits the lift amount from being shifted from the first lift amount region to other lift amount region.