Abstract: Shrouded engine cooling fan in which the interface between an outer stationary shroud fixed with respect to a radiator and an inner and rotating shroud fixed to the tips of the fan blades define a generally toroidal chamber in which a vortex of air is generated in response to the rotational drive of said fan that acts as a seal to block the flow of recirculation air from the fan discharge to the fan entrance over a wide range of fan operating points to increase fan operating efficiency and reduce fan generated noises.

Abstract: A variable speed transverse fan is provided for booster application in multi-ducted heating, ventilating and air conditioning systems for automotive vehicle. The transverse fan may be employed in a front arm rest and is selectively powered to provide air flow control to the rear passengers such as by increasing flow to the rear passenger when the main fan is on low speed. Because of the high turbining loss characteristic of this type of fan, a significant reduction of the air flow to the rear can be obtained if desired by turning the transverse booster fan off when the main fan is on high speed.

Abstract: An engine cooling fan driven through a viscous clutch and having a mechanically shearable drive element into the powered input of the viscous clutch which shears at a predetermined low torque level to prevent fan damage due to viscous clutch lockup and limits fan speeds to a relatively low torque level.