Ball ramp actuator with indexing plates

A clutch assembly for rotationally coupling two rotatable shafts comprising:

• an input shaft rotating about an axis of rotation;
• an output shaft having an axis of rotation;
• a ball ramp mechanism for generating a clamping force comprising;
• an annular control ring having an axis of rotation, said control ring having a plurality of circumferential control grooves formed in a face of said control ring, said control ring varying in axial depth, an equivalent number of rolling elements one occupying each of said control grooves, an activation ring having an axis of rotation coaxial with said axis of rotation of said control ring, said activation ring having a plurality of activation grooves substantially identical in number, shape and radial position to said control grooves where said activation grooves at least partially oppose said control grooves and where each of said rolling elements is contained between one of said activation grooves and a respective control groove, said control ring being axially and rotationally moveably disposed relative to said activation plate, said control ring having an annular control plate radially extending therefrom and said activation ring having an annular activation plate radially extending therefrom;
• an annular intermediate plate nonrotatably connected to said output shaft and disposed between said control plate and said activation plate;
• a coil for creating of an electromagnetic field in a coil pole upon introduction of an electrical current in said coil where said coil pole is magnetically coupled to said control plate and said intermediate plate and said activation plate;
• a first index ring acting to limit the rotation of said activation ring relative to said input shaft;
• a second index ring acting to limit the rotation of said control ring relative to said input shaft;
• where upon introduction of an electrical current in said coil an electromagnetic field is generated to rotationally couple said control plate to said intermediate plate and said intermediate plate to said activation plate.