Patent ID: 8245679

Claim:
A variable valve timing apparatus for adjusting valve timing of a valve which is opened and closed by a camshaft driven by torque transmission from a crankshaft in an internal combustion engine, the apparatus comprising: a case defining a fluid chamber inside; magneto-rheological fluid kept in the fluid chamber, the magneto-rheological fluid having a viscosity variable in accordance with magnetic flux passing through; a control device which carries out variable control of the viscosity of the magneto-rheological fluid by varying the magnetic flux; a rotor rotatably supported on the case and penetrated the case to come into contact with the magneto-rheological fluid so that the rotor receives a braking torque according to the viscosity of the magneto-rheological fluid; an angular phase adjusting mechanism engaged with the rotor at an outside of the case for adjusting an angular phase difference between the crankshaft and the camshaft according to the braking torque acting on the rotor; and a sealing device provided between the case and the rotor, wherein the sealing device comprising: a magnet supported on one of the case and the rotor for supplying magnetic flux; a plurality of flux guides supported on one of the case and the rotor and annularly arranged along the rotational direction of the rotor for defining a plurality of guide gaps with the other one of the case and the rotor, and for guiding the magnetic flux to the guide gaps, the guide gaps being arranged in a multi row fashion between an inside and an outside of the case; and further comprising: a nonmagnetic shield member for covering the sealing device in the case, wherein the distances of the guide gaps are smaller than a thickness of the nonmagnetic shield member.