Synchronous motor system employing a non-synchronous motor for enhanced torque output

Claim 1

A motor-driven actuator for providing synchronous torque at an actuator output member, said actuator designed for driving, through the actuator output member, a load having a predetermined minimum torque requirement and a predetermined maximum torque requirement greater than the predetermined minimum torque requirement, comprising a) a frame; b) a torque linkage mounted on the frame and having first and second input members cumulatively applying torque received at the torque linkages's input members to the actuator output member; c) a synchronous motor mounted on the frame and having an output member connected to provide torque to the torque linkage's first input member; d) a first torque limiting clutch transmitting a preselected maximum amount of torque from an input member thereof to an output member thereof connected to provide torque to the second input member of the output linkage; and e) a non-synchronous motor mounted on the frame and having an output member connected to provide torque to the input member of the first torque limiting clutch, wherein the synchronous motor has a maximum torque capacity such that the torque applied to the load by the synchronous motor through its output member and the torque linkage to the torque linkage'output member, is no less than the difference between the predetermined maximum and minimum load torque requirements.