Abstract: A split rotor cooling fan clutch includes an input member that is constantly driven at engine speed, or at some selected proportion thereof. An output member is journaled on the input member so as to be supported thereon in a substantially nonrotating state when decoupled and alternately, to be concentrically rotatable in concert therewith at a variety of speeds. A space presented between the input and output members contains a quantity of magnetorheological fluid. An engagement mechanism includes the split rotor and coil, with a ferromagnetic element positioned to define an operative gap between the rotor and the ferromagnetic element. The coil is selectively energized with a given current to result in a torque transfer between the input and output elements that provides a rotational speed of the fan tailored to the cooling requirements of the associated engine. Internal heat generation is managed electronically to prevent overheating.

Abstract: A magnetorheological fluid fan clutch effects modulated rotational motion transmission between a rotatable input shaft carrying an input clutch plate and a housing having a front cover and a rear cover forming a cavity about the input clutch plate wherein the front and rear covers operate as output clutch plates. A nonmagnetic spacer is positioned between the front and rear covers and radially outside the input clutch plate. A bearing supports the housing on the input shaft through the rear cover so that the input clutch plate is rotatable on the input shaft relative to the housing. Magnetorheological fluid is carried in the cavity, through which torque is variably transferred between the input clutch plate and the housing.

Abstract: A magnetorheological fluid fan clutch effects modulated rotational motion transmission between a rotatable input shaft carrying an input clutch plate and a housing having a front cover and a rear cover forming a cavity about the input clutch plate wherein a core carried in the front and rear covers operates as output clutch plates. Bearings support the housing on the input shaft through the front and rear covers so that the input clutch plate is rotatable on the input shaft relative to the housing. Magnetorheological fluid is carried in the cavity, through which torque is variably transferred between the input clutch plate and the housing. A coil is positioned radially outside the non-magnetic spacer and carries a variable electrical current to effect a variable magnetic field across the input clutch plate and through the magnetorheological fluid providing modulated torque transmission between the input clutch plate and the core.