Patent ID: 7913825

Claim:
An electronically controlled viscous fluid coupling assembly for a fan member comprising: (a) an output member configured for attachment to a fan member; (b) an input member bearing mounted to said output member and rotatable around said output member and at input speed, said input member comprising a body member and a cover member; (c) a stationary mounting member bearing coupled to said input member; (d) a viscous fluid supply mechanism positioned within said input member and comprising a rotor member, a reservoir plate member having a fluid aperature, a fluid reservoir, a fluid chamber, a working chamber and a quantity of viscous fluid; (e) an electromagnetic member mounted on said stationary mounting member; (f) an electromagnetically actuated valve mechanism for controlling viscous fluid engagement of said output member with said input member, said valve mechanism having a moveable member for opening, partially opening and covering said fluid aperature responsive to a magnetic field generated by said electromagnetic member; and (g) a differential speed sensor mechanism for determining the rotational speed of said output member, said differential speed sensor mechanism comprising a magnetic sensing device coupled to said stationary mounting member, a pole member attached to said input member, and a multi-pole ring magnet member; wherein the differential speed of the input member and output member is determined by the difference in speed between said pole member and said ring magnet member; and wherein the operation and the speed of a fan member is controlled by said viscous fluid coupling assembly without a wire tether member.