Patent ID: 7677376

Claim:
An electromagnetic frictionally engaged clutch having the features: a) the clutch comprises a rotor part which is provided with a friction lining and is connected in a rotationally fixed fashion to a first shaft and on which an electric coil is arranged, as well as an armature plate which can be moved in a rotationally fixed fashion but axially movable from an engaged end position into a disengaged end position and is connected to a second shaft; b) a first permanent magnet is arranged on the rotor part; c) the clutch comprises at least one second permanent magnet which is arranged between the armature plate and a stop, wherein the at least one second permanent magnet exerts an axial force on the armature plate which is opposed to the magnetic force of the first permanent magnet; d) the first permanent magnet and the at least one second permanent magnet are selected such that the resulting force is exerted on the armature plate by the first permanent magnet and the at least one second permanent magnet forces the armature plate against the friction lining of the rotor part when the coil is not energized if the armature plate is in its engaged end position and the armature plate is forced against the stop which is spaced apart axially from the friction lining of the rotor part if it is in its disengaged end position, and e) currents can be applied to the electric coil in such a way that the magnetic field generated thereby moves the armature plate into its engaged end position or its disengaged end position as a function of the direction of the current.