APPARATUS AND METHOD FOR CONTROLLING AN INTERNAL COMBUSTION ENGINE

A control device for an engine, the engine includes an exhaust gas control apparatus that is configured to store NOx and react NOx with a reduction agent. The control device includes an electronic control unit. The electronic control unit is configured to: (i) execute a rich spike control, the rich spike control is a control executed to temporarily change an in-cylinder air-fuel ratio from a leaner air-fuel ratio than the stoichiometric air-fuel ratio to the stoichiometric air-fuel ratio or a richer air-fuel ratio than the stoichiometric air-fuel ratio, and (ii) vary an overlap amount of an intake valve and an exhaust valve such that the overlap amount is less during non-execution of the rich spike control than during execution of the rich spike control, in an operation range where a pressure of the intake port becomes higher than a pressure of the exhaust port.