INTERNAL COMBUSTION ENGINE CONTROL APPARATUS

An embodiment (control apparatus) for an internal combustion engine according to the present invention determines, based on an output value Voxs of the downstream air-fuel ratio sensor 67 disposed downstream of a three-way catalyst 43, determines which air-fuel ratio request, a rich request or a lean request, is occurring. The control apparatus sets a target upstream air-fuel ratio abyfr to a target rich air-fuel ratio afRich when the rich request is occurring, and sets the target upstream air-fuel ratio abyfr to a target lean air-fuel ratio afLean when the lean request is occurring. Each of the target rich air-fuel ratio afRich and the target lean air-fuel ratio afLean is varied depending on an intake air amount Ga. Further, the control apparatus increases a purge amount of an evaporated fuel as a magnitude (air-fuel ratio change amount AF, | afLean - afRich | ) of a difference between the target rich air-fuel ratio afRich and the target lean air-fuel ratio afLean becomes larger.