Valve actuating apparatus for internal combustion engine

摘要

A valve actuating apparatus for an internal combustion engine selectively operating in the normal Otto cycle or the Miller cycle is provided which enables the engine to achieve stable combustion and improved fuel economy during cruising or in a low-load engine operating region. A delayed-closing cam for Miller cycle operation and a normal cam having a cam profile for earlier valve-closing timing of the intake valve than a cam profile of the delayed-closing cam are provided on a camshaft. A cam profile-switching mechanism switches between the delayed-closing cam and the normal cam, for opening and closing the intake valve. An ECU controls the switching mechanism such that when a detected operating condition of the engine indicates starting or idling, the intake valve is operated by the normal cam, and when the detected operating condition indicates cruising, the intake valve is operated by the delayed-closing cam.