Abstract: A viscous fluid clutch includes a cover having an airflow ring. The airflow ring can be formed integrally with or separately from the cover. Concentric inner and outer walls are attached to each other by radially spaced fins. A cooling passage for airflow is provided between each pair of adjacent fins. During rotation, a cooling airflow passes freely between the fins, improving the rate of heat transfer from the clutch. Such construction of the walls and fins and a method for forming the cover are well suited for casting and eliminate the need for costly prior art machining. A labyrinth seal can be formed between the cover and housing by an annular flange on the housing received into a complementary groove in the cover.

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.