CONTROL DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

The objective of this invention is to control valve timing appropriately on the basis of fuel properties and the engine temperature, thereby improving exhaust emissions. An engine (10) is equipped with a function whereby variable valve mechanisms (36, 38) are driven, thereby controlling the delayed opening of an intake valve and controlling the early closing of an exhaust valve. An ECU (60) variably sets a low temperature determination value (T1) on the basis of the alcohol concentration in the fuel. When the engine water temperature (Thw) is equal to or less than the low temperature determination value (T1), intake valve delayed opening control is prohibited and exhaust valve early closing control is permitted. Thus, during cold operation it is possible to avoid deterioration in combustion performance (deterioration of in-cylinder turbulence) due to the intake valve control, and to prevent deterioration in exhaust emissions. Furthermore, because exhaust valve control is permitted, it is possible to ensure a negative overlap period which satisfies the control requirement by advancing the valve-closing timing of the exhaust valve (34), for example. Accordingly, it is possible to improve exhaust emissions and the warmup performance of a catalyst.