Warner Electric Brake & Clutch Company

Thomas P Roll

An apparatus and method is provided for energizing a multiple-turn winding of an electromagnetic coupling having an armature and a rotor separated by an air gap; in response to the closure of the air gap, the energization of the winding is reduced so as to reduce the torque coupling between the armature and rotor. By reducing the initial torque coupling between the armature and rotor the frictional vibrations of the coupling--which occur during engagement of the armature and rotor and which generate audible noise--are reduced and the coupling engages more smoothly and quietly. Preferably, the energization of the winding is reduced in response to the increased magnetic inductance of the winding resulting from the closure of the air gap between the armature and rotor. Also, the torque coupling between the armature and rotor is preferably minimized in response to the increased magnetic inductance so as to provide 100% slippage upon initial contact of the rotor with the armature. From the reduced energization of the winding occurring after the closure of the air gap, the energization of the winding is controlled to gradually increase to full torque coupling and 0% slippage. To further reduce the audible noise upon engagement of the armature and rotor, the flux gaps in both the armature and rotor are composed of non-magnetic areas which are asymmetrically positioned in the magnetic material comprising the armature and rotor. By asymmetrically positioning the non-magnetic areas, the audible noise from the vibrations of the armature and rotor is reduced; the vibrations are caused by the frictional slippage between the armature and rotor upon their initial engagement.

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Janesville, WI, United States of America

Thomas P Roll