Minebea Company, Limited

Haruyoshi Hino

Yuzuru Suzuki

Sakae Fujitani

Hideki Sakiyama

Naomi Inoue

Hiroto Nakamata

A claw pole type synchronous motor has two cylindrical stator assembles arranged back-to-back and a magnetized rotor provided coaxially with the stator assemblies. The rotor has a length larger than the total thickness of the stator assemblies and always covers the inner peripheral surfaces of the stator assemblies so as to reduce vibration due to axial movements of the rotor with respect to the stator assemblies. The motor also has an electrical phase angle defined between the center lines of the corresponding claw poles of the adjacent stator assemblies made equal to the theoretical electrical phase angle minus an electrical angel within a range more than 0.degree. and less than 10.degree..

Motor structure

A motor structure including a rotor 1 having a permanent magnet 10 where north poles and south poles are alternately disposed in a moving direction of the rotor, a stator 5a including at least two stator yokes having stator pole teeth 3a, 4a respectively which face to the permanent magnet at a distance and are respectively positioned side by side in the moving direction to bear north poles or south poles respectively due to an electric current flowing through a coil 2a to thereby form at least one phase, wherein the stator pole teeth 3a, 4a are different from each other with respect to an effective area through which magnetic flux passes, whereby high harmonic wave phases generated from the pole teeth 3a, 4a are different from each other by 180 degrees in electric angle to thereby be canceled mutually, therefore an induced electromotive force wave containing hardly high harmonic wave is obtained to thereby reduce a motor vibration.

To reduce as much as possible the motor vibration due to the effect of harmonic components contained in the induced electromotive force waveform induced in the armature coil. In a motor structure, the pole tooth shapes of one pole tooth and the corresponding pole tooth thereto constituting one phase are made different from each other by changing their areas or amounts of skew, whereby the third harmonics caused by variations in the magnetic fluxes interlinking with these pole teeth are caused to cancel each other. Thus, the rotational vibration which has hitherto been a problem can be reduced and, further, the accuracy of the rotor movement can be improved without lowering the dynamic torque characteristic of the motor.

A claw pole type synchronous motor has input frequency increasing portions in a form of notches or holes formed in portions of claw poles which have the lowest magnetic flux densities so that the motor operates in a range from a low frequency to a high frequency without lowering torques too much.

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Shizuoka-ken, Japan

Haruyoshi Hino