Patent ID: 7102265

Claim:
A four-pole synchronous motor comprising: a housing: an output shaft rotatably supported in the housing; a cylindrical magnet rotor having four magnetic poles, said magnet rotor being rotatably supported in said housing on said output shaft; a stator, through which the output shaft extends, provided in a space encased by said magnet rotor, said stator having a stator core on which armature coils are formed with bobbins, the stator core having first magnetic pole cores formed at opposing sides of a connection body part of crisscrossed connected body parts and second magnetic pole cores formed at other opposing sides of the connection body part, the first magnetic pole cores including magnetic flux acting surface parts extended at opposing sides of the first magnetic pole cores in a circumferential direction, and a shape of each of the magnetic flux acting surface parts on one side of a longitudinal centerline of the first magnetic pole cores being different from that on another side by having a concave section for partially increasing magnetic resistance on the one side, so as to be magnetically asymmetrical with respect to the longitudinal centerline, and the magnetic flux acting surface parts of the first magnetic pole cores and the second magnetic pole cores, which face said magnet rotor, being formed in the circumferential direction to extend an angle in a range of 50–70 degrees.