Electric drive system with a selectable one-way clutch

A system for selectively rotating a rear drive axle including a pair of rear drive axles of a vehicle having an engine providing primary propulsive torque to a front drive axle of the vehicle, a gear set with a first set of rotatable elements, and a differential with a second set of rotatable elements, the system comprising:

• a motor having a rotor;
• a pair of selectable one-way clutch (SOWC) assemblies wherein each SOWC assembly of the pair of SOWC assemblies is positioned on a respective one of the pair of rear drive axles, and wherein each SOWC assembly of the pair of SOWC assemblies is configured for transferring a torque from the rotor to a respective one of the pair of rear drive axles when the pair of SOWC assemblies is engaged, and for preventing rotation of the rotor and each of the first and second set of rotatable elements when the pair of SOWC assemblies is disengaged;
• and
• a controller operable for detecting when additional propulsive torque is required above a level of the primary torque, for transmitting a motor control signal to the motor to turn on the motor when the additional propulsive torque is required, and for selectively engaging the pair of SOWC assemblies when the motor is running to thereby transfer torque from the rotor to the rear drive axles.

A method for minimizing parasitic spin losses in an electric rear drive motor (eRDM) motor system operable for rotating a pair of rear drive axles in a vehicle having a controller and an engine powering a front drive axle, the eRDM system having an electric motor, a reduction gear set with a first set of rotatable elements, and a differential positioned between the pair of rear drive axles with a second set of rotatable elements, the method comprising:

• turning the electric motor on using the controller when additional propulsive energy is required above a primary propulsive energy level provided by the engine;
• engaging a pair of selectable one-way clutch (SOWC) assemblies via the controller when the electric motor is on and the engine is powering the front axle to thereby transfer torque from the electric motor to the pair of rear drive axles;
• and
• disengaging the pair of SOWC assemblies via the controller to thereby prevent rotation of a rotor portion of the motor and of the first and second set of rotatable elements when the electric motor is off.