US 5,962,947 AGranted

Motor structure

AssigneeMinebea Co., Ltd.

InventorsYuzuru Suzuki, Haruyoshi Hino, Sakae Fujitani, Naomi Inoue, Hideki Sakiyama

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Abstract

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.

Claims7

Dependent claims

A motor structure having a first part with N and S magnetic poles disposed fixedly and alternately and a second part having pole teeth provided corresponding to the magnetic poles of the first part and spaced apart therefrom, each polarity of the pole teeth being changed so as to cause movement between said first part and said second part, the motor structure comprising:

an outer yoke including said second part;
an inner yoke including said second part;
first trapezoidal pole teeth, each having a first slant portion and being disposed in a periphery of said outer yoke at even intervals;
second trapezoidal pole teeth, each having a second slant portion which differs in size from said first slant portion, said second teeth being disposed at a center position between respective ones of said first pole teeth;
and
a coil exciting said first and second pole teeth;
whereby third harmonics generated by changes in magnetic fluxes interlinking with the first and second pole teeth are caused to cancel one another, and
a slant S of the first and second pole teeth is defined by the equation S=2C/.tau.P, where C is defined as one half of the slant portion of the lateral side of the pole teeth and .tau.P is defined as the pole pitch.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/910,253Filed 13 Aug 1997
Priority: JP 8-27648718 Oct 1996
Granted: 5 Oct 1999
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H02K 1/145
Stator cores with salient poles: having an annular coil, e.g. of the claw-pole type
H02K 21/145
With magnets rotating within the armatures: having an annular armature coil
H02K 2201/06
Specific aspects not provided for in the other groups of this subclass relating to the magnetic circuits: magnetic cores, or permanent magnets…
H02K 2201/12
Specific aspects not provided for in the other groups of this subclass relating to the magnetic circuits: transversal flux machines