Electromagnetic clutch with asymmetric spoke patterns

摘要

An electromagnetic clutch assembly for transfer cases (16) and other motor vehicle powertrain applications includes a friction disc clutch pack (150) and an electromagnetic operator that applies compressive force to the clutch pack. The electromagnetic operator includes an electromagnetic coil, a rotor (170) partially surrounding the coil, an armature (174) and a ball ramp operator (152) assembly that provides compressive force when the coil is energized. The rotor and armature include aligned paths or tracks of arcuate slots (246) separated by webs or spokes (248) which create a sinuous magnetic flux path and improve performance. The number of slots and thus the number of spokes in the rotor and armature paths are unequal. This inequality greatly reduces pulsations caused by small fluctuations in clutch engagement associated with the repeated, simultaneous alignment and non-alignment of the spokes in a rotor and armature having equal numbers of spokes. This results in improved smoothness of operation and reduces noise and vibration.