Patent ID: 7667364

Claim:
A brushless motor, comprising: a stator that includes: an annular stator core having teeth arranged with a spacing in a circumferential direction of the annular stator core; and coils wound around the teeth respectively; and a rotor that includes a rotor core and magnetic poles of segment magnets arranged annularly along a circumferential direction of the rotor core, the segment magnets stacked at a plurality of stages in an axial direction of the rotor core, wherein a length direction of each of the segment magnets is parallel with the axial direction of the rotor core; and wherein the following expression is satisfied: (2×β/ P )+θ<(360/ P ) where P is the number of the magnetic poles of the segment magnets at each stage, β (electrical angle) is the effective pole angular aperture on the outer peripheral surface of the rotor core, and θ is the skew angle equivalent to a phase shift angle between the corresponding magnetic poles of the segment magnets at the adjacent stages.