US Patent 7355310 Permanent magnet synchronous motor

A permanent magnet synchronous motor is of a rotating magnetic field type, and includes a stator which generates a rotating magnetic field, and a rotor having fixed magnetic poles. The rotor includes first and second rotor units arranged axially thereof. The first and second rotor units each have a rotor core, and permanent magnet pieces bonded on the outer peripheral surface of the rotor core. The rotor cores of the first and second rotor units are engaged with each other. The rotor cores each have pin insertion holes into which guide pins are inserted to position the rotor units in proper circumferential positional relation with respect to each other when the rotor cores are connected to each other by bolts.