Abstract: A device for varying steplessly, throughout the operating range of an internal combustion engine, the duration of the processes of induction and exhaust, and the lift of the valves associated with these processes; the device employing, within a four valve combustion chamber, a pair of valves for each of the functions of induction and exhaust; each pair of valves being driven by a different camshaft; for each valve, a rotatable drum of common axis with the camshaft, and having a valve actuating rocker arm pivoted at one end within the drum; wherein angular rotation of the drum causes the cam to reciprocate the rocker arm, and therefore, the valve, at a point earlier or later in cam rotation; the combination, for instance, of an advanced opening point of the first valve, and a retarded closing point of the second valve, giving an extended duration of the process associated with the two valves.

Abstract: A control system for controlling intake and exhaust valves of an internal combustion engine includes electromagnetic actuator means for opening and closing the intake and exhaust valves. When the engine is idling, drive signals applied to the electromagnetic actuator means for selected cylinders are cut off, so that only the other cylinders are enabled.