Torque transfer clutch with ball screw actuator

A transfer case for distributing torque between first and second drivelines of a motor vehicle, comprising:

• a first output arrangement adapted to transfer drive torque from the engine to the first driveline;
• a second output arrangement adapted to drive the second driveline;
• a control system including a sensor for sensing an operating characteristic of the vehicle and controller for receiving an input signal from said sensor and generating an electric output signal in response thereto;
• a transfer clutch having a clutch pack of interleaved first and second clutch plates operably connected respectively to said first and second output arrangements;
• and
• a power-operated actuator adapted to be activated by said output signal of said controller, said actuator including an electric motor having a rotatable output member, a drive member arranged concentrically with said output member and adapted to move linearly in response to rotation of said motor output member for applying a clutch engagement force on said clutch pack, and balls retained in threads formed between said motor output member and said drive member.

A transfer case for transferring drive torque between

• a primary driveline and a secondary driveline, comprising:
• a first output adapted to drive the primary driveline;
• a second output adapted to drive the secondary driveline;
• and
• a controllable coupling between said first output and said second output including a clutch assembly having a first set of clutch plates coupled to said first output and interleave with a second set of clutch plates operably coupled to said second output, and an electric operator for selectively effecting torque transfer between said first and second outputs, said electric operator including a motor having a fixed stator and a bi-directionally rotating output member, a bi-directionally translating lead screw for selectively engaging said interleaved clutch plates, and balls disposed in threads formed between said motor output member and said lead screw.