Permanent magnet elevator disk brake

摘要

A brake assembly (18) includes a permanent magnet (36) that generates a first magnetic field (52) in a direction that causes application of a clamping force on a brake disk (22). An electromagnet (38) is energized with current of a proper polarity to generate a second magnetic field (54) opposite the first magnetic field (52). The rate and magnitude at which current is applied produces a controlled repulsive force between the two magnetic fields (52, 54) to disengage the brake disk (22). As a distance between the permanent magnet (36) and the electromagnet (38) increases, the difference in field strength decreases until an equilibrium position is obtained. The brake is applied and released in a controlled manner by varying the strength of the second magnetic field (54) relative to the first magnetic field generated by the permanent magnet (36).