Abstract: A turbocharger drive system associated with an internal combustion engine includes a plurality of turbochargers drivable by exhaust gases from the engine, a plurality of rotary electric machines mounted on the rotatable shafts, respectively, of the turbochargers and operable as electric motors or generators, and a single rotary electric machine coupled to the rotatable shaft of the engine. When the engine rotates at a low speed and under a high load, the rotary electric machine coupled to the engine shaft operates as an electric generator to generate electric power to drive the rotary electric machines mounted on the turbocharger shafts as electric motors, so that the boost pressure is increased to increase the output power of the engine. Since the multistage turbochargers are power-assisted by the respective rotary electric machines, the boost pressure builds up sharply.

Abstract: An electromagnetic valve control system includes electromagnets having fixed magnetic poles facing opposite end surfaces of a reciprocally movable magnetic plate which is coupled to each of intake and exhaust valves. The intake and exhaust valves can be opened and closed under electromagnetic attractive forces produced by energizing the electromagnets. When the rotational speed of an engine incorporating the electromagnetic valve control system is lower than a predetermined speed, the intake and exhaust valves are opened and closed at a timing close to the top dead center and the bottom dead center of an engine cylinder associated with the intake and exhaust valves. The speeds of flow of intake air and exhaust gases are detected, and when the rotational speed of the engine is higher than the predetermined speed, the timing of closing the intake and exhaust valves is modified such that the intake and exhaust valves will be closed at the time the speeds of flow of intake air and exhaust gases become zero.