Patent ID: 7385321

Claim:
A motor having shifted teeth of pressed powder construction, comprising: an inner rotor; and a cylindrical stator arranged concentrically with the rotor and with an air gap therebetween; said stator having two spaced stator elements and a ring shaped permanent magnet held between the stator elements and magnetized so as to form N and S poles in the axial direction of the stator, a plurality of small stator teeth A and Ā separated in the axial direction of the stator from each other and formed on the inner peripheral surface of one of the spaced stator elements, a plurality of small stator teeth B and B separated in the axial direction of the stator from each other and formed on the inner peripheral surface of the other of the spaced stator elements, and stator windings for A phase and B phase wound around the stator elements, respectively; said rotor having a plurality of small rotor teeth formed on the outer peripheral surface thereof similar in number to the small stator teeth, wherein each of said stator and said rotor is formed of pressed powder comprising a soft magnetic material and at least one of a resin and an inorganic material, and wherein said small rotor teeth are arranged axisymmetrically with vernier pitch, wherein a ratio of a thickness of the small stator teeth Ā in the axial direction of the stator to a thickness of the small stator teeth A in the axial direction of the stator is set to a value smaller than 1 so as to equalize substantially in mean permeance both small stator teeth A and Ā to each other, and wherein a ratio of a thickness of the small stator teeth B in the axial direction of the stator to a thickness of the small stator teeth B in the axial direction of the stator is set to a value smaller than 1 so as to equalize substantially in mean permeance both small stator teeth Ā and B to each other.