US Patent 11143256 Magnetically actuated brake

A magnetic brake for a motor uses the magnetic force on the surface of a flux concentrating rotor to pull a flexible brake spring or friction sheet into friction contact with the rotor. An electromagnetic stator pulls the flexible brake spring or friction sheet away from the rotor when it is energized. The brake spring may be a variable thickness around the circumference in a radial flux motor or radially in an axial flux motor and is thicker near where it is fixed to the housing. The brake spring may be split so it can clamp down on the rotor symmetrically. The OD of the brake spring may be closer to the surrounding stator near the fixed section of the brake spring so the air gap to the brake stator is smaller and the gap to the rotor and the ID of the brake spring is larger to allow the brake stator to pull on this area with greater force initially when it is energized to disengage the brake.