A fluid friction coupling for driving a fan of an internal combustion engine includes a solenoid configured such that it surrounds a drive shaft and is operatively arranged for moving a control part. The control part moves a valve body which controls the flow of a viscous fluid into a working chamber. The fluid friction coupling is of particularly compact configuration and magnetic losses are kept particularly low.

A fan clutch assembly for a vehicle includes an electromagnetic control assembly for actuating a rotatable valve plate. A rotatable shaft is connected to the valve plate. A ferromagnetic element is slidably mounted on the shaft. When an electromagnetic coil is energized, the resulting flux attracts the ferromagnetic element. As the ferromagnetic element slides, it is rotated to cause rotation of the shaft, thereby opening the valve plate.

A self-supporting brush holder assembly 10 is disposed on the cylindrical outer surface of a shaft 20 of a viscous fan drive 11 which is rotatable about an axis of rotation 25. The brush holder assembly includes a first portion 12 having a generally C-shaped concave surface 16 and a second portion 14 having a generally C-shaped concave surface 18 which is adaptable to mate with the generally C-shaped concave surface of the first portion to define an annular surface 28 defining a cylindrical opening having its longitudinal axis adapted to be disposed coaxial to the axis of rotation. The cylindrical opening is adapted to surround the cylindrical outer surface of the shaft 20 with the annular surface 28 being disposed contiguous to the cylindrical outer surface of the shaft 20 to support the first and second portions 12, 14 on the shaft 20 to prevent radial movement between the shaft and the first and second portions. The brush holder 10 includes channels 44 located in one of the first and second portions disposed in a generally radial direction and brush members 22 and 24 are located in the channels and are biased in a radially inwardly direction so that one brush member engages with a commutating ring located on the shaft and the other brush member engages with the outer surface of the shaft. The shaft 20 includes an annular groove 50 therein and the annular surface 28 includes a complementary annular land 48 thereon which is adapted to be received in the annular groove 50 of the shaft 20 to positively locate the brush holder relative to the shaft and prevent movement in an axial direction therebetween. A tether member 58 is secured to one portion of the brush holder at one end thereof and is adapted to be secured to a fixed member 64 at the opposite end thereof to prevent rotation of the first and second portions upon rotation of the shaft.

A fluid coupling device is provided of the type including an input coupling (11) and an output coupling assembly (13) including a case cover member (17) including a chimney portion (39) and chimney extension (81). The coupling includes a valve plate (31) defining a fluid port (45), and operation of the coupling is controlled in response to the rotational position of the valve arm (43), by means of a valve shaft (41). The position of the valve shaft (41) is controlled, in response to an electrical input signal by means of an actuator assembly (61), which includes an annular steel housing member (63). The housing member is stationary, and is mounted relative to the chimney extension (81) by means of a set of ball bearings (77) which comprise the only bearing support between the actuator assembly (61) and the rotating coupling. As a result of this design, there is no high speed interface between the rotating coupling and the stationary actuator assembly to result in excessive wear, heat generation, and degradation of performance.

Disclosed is a fluid friction clutch assembly, comprising a drive shaft; a primary disk mounted for rotation on the drive shaft; a driven clutch housing surrounding the primary disk and being rotatably supported with respect to the drive shaft, the clutch housing containing a partition therein defining a work chamber and a reservoir separated by the partition, wherein the partition includes in its radially outer area at least one overflow opening closeable by means of a valve lever comprised of a magnetic material and a return flow orifice associated with pump means for pumping a viscous torque-transmitting medium from the work chamber to the reservoir; a pulley member mounted on the drive shaft for driving the shaft and means, associated with the pulley member, for selectively magnetically actuating the valve lever, in order to selectively open and close the overflow opening.