Electromagnetic clutch having high torque transfer

Abstract

A high torque transfer electromagnetic clutch having a rotor which is rotated by an external driving power source through a belt, an armature plate attached to a drive shaft and an electromagnetic means for selectively attracting the armature plate into engagement with the rotor for transmitting the rotation of the driving power source to the drive shaft via respective frictional surfaces. In one embodiment of the invention, one frictional surface is machined to a rough surface with a plurality of uniformly formed peaks, each peak having an acute shape. The surface is then covered with a film layer of plating. The other frictional surface is finished by polishing. When the frictional surfaces engage, particles from the film layer are shaved off and accumulated in minute depression in the other frictional surface. Particles are also shaved from the other frictional surface and adhere to the film layer particles to form a material which exhibits a high resistance to the shear forces created by the rotating rotor. Accordingly, the level of torque transferred by the clutch is increased. In other embodiments of this invention, the peaks of the machined frictional surface are trapezoidal in shape, thus providing more contact surface upon engagement of the frictional surfaces and thereby increasing the amount of torque transferred. In a further embodiment of the invention, the film layer is formed from a powder material.