Abstract: A viscous fluid clutch includes an internally-mounted pump plate for separating a working chamber from a reservoir. Discharge ports in the pump plate permit fluid flow from the reservoir to the working chamber. Return orifices in the pump plate direct return flow back to the reservoir. A rotatable control arm is supported by arcuate baffle walls formed in a cover to enhance the seal provided at the discharge ports. The baffle walls limit the amount of fluid which can collect at a discharge port from the reservoir when the clutch is at rest.

Abstract: A viscous fluid clutch includes an internally-mounted pump plate for separating a working chamber from a reservoir. Fill openings in the pump plate permit fluid flow from the reservoir to the working chamber. Orifices in the pump plate direct return flow back to the reservoir. Fluid accumulators formed in a cover are aligned with each of the pump plate orifices. A non-radical channel formed in the cover begins at a respective accumulator and terminates at an inner reservoir chamber. Centripetal forces of the rotating clutch pump fluid from the accumulators to the reservoir. The geometry of the channels prevents migration of fluid from the reservoir to the working chamber without the use of mechanical valves when the clutch is at rest.

Abstract: A viscous fluid fan clutch assembly for a vehicle includes an internally-mounted pump plate for separating a working chamber from a reservoir. A plurality of pressure-sensitive fluid check valves are provided in the pump plate to permit only one-way fluid flow from a pumping chamber to the reservoir. Each check valve includes an interior chamber having a pair of angled side walls which terminate at a normally-closed outlet. When a predetermined fluid pressure is achieved in the pumping chamber, the side walls are forced apart to open the outlet. The closing of the outlet is not dependent upon fluid pressure in the reservoir.