Patent ID: 7939976

Claim:
A rotary electric machine comprising: a shaft; a two-phase stator, arranged around the shaft and including an approximately ring-shaped magnetic body, and a plurality of main poles projecting radially from the magnetic body, each main pole including a plurality of inductor teeth arranged at a tip thereof; and a rotor portion including first and second rotor units which have substantially the same structure and are fixed to the shaft, each of the first and second rotor units including a pair of rotor magnetic poles and a permanent magnet arranged therebetween, each rotor magnetic pole including a plurality of fine teeth which are arranged at a substantially regular pitch and opposed to the stator via an air gap, the fine teeth of one of the pair of rotor magnetic poles being offset by half a pitch from the fine teeth of the other rotor magnetic pole, the adjacent rotor magnetic poles of the first and second rotor magnetic poles being arranged with their fine teeth aligned with each other in an axial direction and having the same magnetic polarity; wherein the plurality of inductor teeth of each main pole of the stator include a pair of innermost inductor teeth arranged at a first pitch in a central portion of the main pole, a pair of intermediate inductor teeth arranged on the outside of the innermost inductor teeth and at a second pitch from the innermost inductor teeth, and a pair of outermost inductor teeth arranged on the outside of the intermediate inductor teeth and at a third pitch from the intermediate inductor teeth, each of the first pitch, the second pitch, and the third pitch being different from a tooth pitch of the fine teeth of the rotor magnetic poles, and at least one of the first pitch, the second pitch, and the third pitch being different from the other ones of the first pitch, the second pitch, and the third pitch; a sum of a vector of a permeance of one of the innermost inductor teeth, a vector of a permeance of an adjacent one of the intermediate inductor teeth, and a vector of permeance of an adjacent one of the outermost inductor teeth in the fourth harmonic plane is substantially zero; a sum of vectors of permeances of inductor teeth at symmetrical positions with respect to a center line of the main pole in the fourth harmonic plane is substantially zero; and vectors of permeances of the innermost, intermediate, and outermost inductor teeth for the first rotor unit in the fourth harmonic plane and vectors of permeances the innermost, intermediate, and outermost inductor teeth for the second rotor unit in the fourth harmonic plane are canceled out by each other.