Patent ID: 8878410

Claim:
A rotor for an electric rotating machine, the rotor comprising: a hollow cylindrical rotor core; and a plurality of permanent magnets embedded in the rotor core so as to form a plurality of magnetic poles on a radially outer periphery of the rotor core, the magnetic poles being arranged at predetermined intervals in a circumferential direction of the rotor core so that polarities of the magnetic poles alternate between north and south in the circumferential direction, wherein the rotor core has a plurality of openings each of which extends in the axial direction of the rotor core so as to penetrate the rotor core, when viewed along the axial direction of the rotor core, each of the openings is symmetrically positioned with respect to a centerline of a corresponding one of the magnetic poles which bisects the corresponding magnetic pole in the circumferential direction of the rotor core, for each of the openings, there are provided n reinforcing portions, where n is an integer not less than 2, the n reinforcing portions extend to connect a pair of radially-inner and radially-outer peripheral portions of the rotor core which are respectively positioned radially inside and radially outside the opening, thereby partitioning the opening into (n+1) parts, such that in the radially-inner and radially-outer peripheral portions of the rotor core connected by the n reinforcing portions, only the radially-inner peripheral portion of the rotor core is positioned radially inside the permanent magnets forming the corresponding magnetic pole, and when viewed along the axial direction of the rotor core, the n reinforcing portions are symmetrically arranged with respect to the centerline of the corresponding magnetic pole and positioned closer to the centerline of the corresponding magnetic pole than the permanent magnets forming the corresponding magnetic pole.