Torque transfer device with hydrostatic torque control system

Abstract

In one form, the present teachings provide a power transmission device that includes a rotatable input shaft, a rotatable output shaft and a ring gear fixed for rotation with the input shaft. A carrier is fixed for rotation with the output shaft. A pump assembly includes an inner rotor supported for rotation on the carrier and an outer rotor encompassing the inner rotor. The outer rotor is in driving meshed engagement with the ring gear. The pump provides pressurized fluid to one of first and second fluid ports. A flow restrictor is moveable to selectively restrict fluid flow relative to one of the first and second ports. In another form, the present teachings provide a power transmission device with a ring gear and a carrier assembly that are coupled to first and second rotary members, respectively. The carrier assembly includes pump assemblies, each of which having a rotor pin, an inner rotor rotatably received on the rotor pin, and an outer rotor that is rotatably received over the inner rotor. The outer rotors have planet gear teeth that are meshingly engaged with teeth of the ring gear. First and second fluid conduits are coupled to first and second sides of the pump assemblies, respectively, to facilitate the flow of hydraulic fluid into and out of the pump assemblies when they are operated in a first rotational direction. A valve is coupled to at least one of the first and second fluid conduits. The valve has a valve element, which is movable between first and second positions, for controlling fluid flow through the valve.