Patent ID: 8643239

Claim:
A motor comprising: a rotor including a rotor core, a plurality of magnet pole portions arranged along a circumferential direction of the rotor core, and a plurality of core pole portions formed integrally with the rotor core, wherein each of the magnet pole portions is formed by embedding a magnet in the rotor core, each of the core pole portions is arranged between the magnet pole portions that are adjacent to each other in the circumferential direction, and each of the core pole portions is spaced apart from the adjacent one of the magnet pole portions by a void; and a stator including a plurality of teeth, which are arranged at equal intervals along a circumferential direction and facing toward the rotor in a radial direction, and a plurality of windings, which are arranged on the plurality of teeth; wherein the magnet pole portions or the core pole portions define first magnetic pole portions, each of the first magnetic pole portions includes a surface, which faces the teeth, and a first opposing part and a second opposing part, which are arranged in an axial direction, the first opposing part includes an auxiliary groove, which has two side surfaces facing toward each other in the circumferential direction, in part of the surface in the circumferential direction, and the second opposing part entirely does not include the auxiliary groove in the surface in the circumferential direction; and where M(°) represents an open angle of the first magnetic pole portion, G(°) represents an open angle of the void, and L represents the number of teeth, an angle D 1 from a center line in the circumferential direction of the first magnetic pole portion to the side surface in the auxiliary groove that is closer to the center line in the circumferential direction satisfies D 1 =M/2+G−a×360(°)/L (where a is a natural number).