Patent ID: 7992531

Claim:
A phase varying apparatus for use with an engine, the phase varying apparatus comprising: an outer cylinder part to which the rotation of a crankshaft of the engine is transmitted; an inner cylinder part that is rotatable relative to the outer cylinder part and that is connected to a camshaft used to open and close an intake valve or an exhaust valve of the engine; and an intermediate member interposed between the outer cylinder part and the inner cylinder part; the phase varying apparatus varying an opening/closing timing of the intake valve or the exhaust valve while creating relative rotations between the outer cylinder part and the inner cylinder part by means of an action of the intermediate member; wherein the improvement comprises: a rotary drum that drives the intermediate member; an electromagnetic clutch including a plurality of magnets that are fixedly arranged at predetermined intervals along a circumferential direction of the rotary drum and that are magnetized alternately in opposite directions and a coil wound around an iron core; and a magnetic flux induction member that is made of ferromagnetic material and that has a plurality of claws each of which is close to a magnetic pole of the magnet, the magnetic flux induction member having a slight gap formed between the iron core and the magnetic flux induction member and having a magnetic path made up of the iron core and the magnets; and wherein the magnetic flux induction member is fixed to the outer cylinder part or to the inner cylinder part, and the rotary drum is accelerated and decelerated by a magnetic force exerted on the magnet by means of the claw, and the intermediate member is driven while controlling an ON state, an OFF state, and a direction of an electric current to be supplied to the coil.