Control system for internal combustion engine

Abstract

To provide a control system for an internal combustion engine, which is capable of providing a stable intake air amount through reduction of pumping loss and blow-back of combustion gases by appropriately controlling the valve-opening timing of the intake valves, and thereby being capable of securing excellent drivability. In the control system, the valve-closing timing of the exhaust valveis changed by an exhaust-side variable valve-operating mechanism, whereby the internal EGR amount is controlled, and the valve-opening timing of an intake valveof an internal combustion engineis changed by an intake-side variable valve-operating mechanism. Further, a target valve-opening timing CAINVO serving as a target of the valve-opening timing of the intake valveis set such that the length of time from the top dead center of a pistonat the start of the intake stroke to the valve-opening timing of the intake valvebecomes equal to the length of time from the valve-closing timing of the exhaust valveto the top dead center, and based on the target valve-opening timing, the intake-side variable valve-operating mechanism is controlled. Further, as the valve-closing timing of the exhaust valve, one of the detected actual valve-closing timing and the set target valve-closing timing is used.