Patent ID: 8754560

Claim:
A permanent magnet rotor, comprising: a rotor core having a generally cylindrical shape with an outer circumferential surface and a rotational axis, the rotor core being entirely formed of a magnetic material; and a plurality of permanent magnets formed in the rotor core and arranged circumferentially at preset angular intervals about the circumferential surface, each of the permanent magnets extending in a direction parallel to the rotational axis and having a center portion, a radially inward side, a radially outward side, and two outer ends that are respectively spaced apart from the circumferential surface by respective bridge regions formed in the rotor core; wherein the outer ends are arranged closer to the circumferential surface than the center portion, and each of the permanent magnets defines a respective intermediate portion in the rotor core that is bounded by the radially outward side of the permanent magnet, the bridge regions at each of the outer ends, and the circumferential surface of the rotor core, such that the intermediate portions are isolated from a remainder of the rotor core by their respective permanent magnets and the respective bridge regions; wherein the material of the bridge regions is metallurgically transformed to possess greater magnetic reluctance than the material of the intermediate portions of the rotor core to reduce magnetic flux leakage from the intermediate portions through the bridge regions and cause the intermediate portions to have an increased magnetic flux density relative to a magnetic flux density of the bridge regions.