Patent ID: 7612480

Claim:
A motor comprising: a rotor portion rotating about a central axis and including: a shaft arranged concentrically with the central axis; a rotor core having a substantially cylindrical shape attached to the shaft; and a plurality of field magnets arranged at an outer circumferential surface of the rotor core facing the central axis, and each of the plurality of field magnets extending in a direction that is substantially parallel to the central axis; wherein the rotor core includes: a plurality of magnet retaining holes accommodating therein the plurality of field magnets; and a plurality of flux barrier holes arranged in the direction that is substantially parallel to the central axis at a space between a corresponding pair of the plurality of field magnets, one magnet in the corresponding pair of the plurality of field magnets having a magnetic polarity different from another magnet in the corresponding pair of the plurality of field magnets; wherein each of the plurality of flux barrier holes is independent of a corresponding pair of the plurality of magnet retaining holes; each of the plurality of magnet retaining holes includes a concave portion extending toward a corresponding flux barrier hole; and each of the plurality of magnet retaining holes includes at a side thereof facing the corresponding flux barrier hole a pair of side portions spaced apart from one another, and each of the plurality of magnet retaining holes includes the concave portion at a portion radially between the pair of side portions.