Electromagnetic clutches are well known in the art and have been utilized commercially in many applications, including automobiles, for a number of years.
A typical electromagnetic clutch includes a rotor which generally comprises an inner annular bearing portion, a clutch portion extending generally radially outwardly from one end of the inner portion, and an outer annular portion extending from the clutch portion in a generally overlying spaced relation with respect to the inner portion. The spacing between the inner and outer annular portions receives an electromagnetic coil to be energized to create a flux field in the rotor which allows attracting a floating plate mounted to the outer annular portion for selective coupling therewith when the electromagnetic coil is energized.
The clutch portion often includes a series of arcuate slots. The purpose of the arcuate slots is to direct the flux field back and forth between the floating plate and the clutch portion of the rotor for efficient magnetic attraction between the floating plate and the rotor.
The reverse clutch, as described in this patent, comprises an additional spring mechanism (metal or elastomeric, with or without pins) that allows for a floating plate to transfer torque to the hub plate by means of friction when the coil is de-activated.
Such a clutch allows selectively coupling and uncoupling of a rotatable shaft mounted to the hub plate.