JPH07308057A - Permanent magnet type synchronous motor - Google Patents

Abstract

PURPOSE:To reduce a cogging torque and reduce the production cost for a permanent magnet by forming the tip portions of a plurality of tooth portions projecting out to the inner side of a hollow cylindrical york portion consisting of a laminated core into a circular projection and setting the radius of curvature of the circular arc within a particular range. CONSTITUTION:A stator 3 consisting of a laminated core provided at a tooth portion 2 projecting out to the inner side of a hollow cylindrical york 1 is formed, and a tip portion 21 of the tooth portion 2 is formed to a circular arc shape in projecting direction. Therefore, an air gap G changing almost in sine wave form is formed along the circumferential direction between a cylindrical permanent magnet 5 and the tip portion 21 of the tooth portion 2 formed to a circular arc shape projecting toward the permanent magnet 5. Here, the radius of curvature of the circular arc of the tip portion 21 is in the range of 0.8 to 1.1 if the width of the tooth portion 2 is W. By doing this, the cogging torque can be reduced and the molding dies for the permanent magnets can be simplified and production cost can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-compact permanent magnet type synchronous motor for driving a microrobot or the like, which generates high torque.

[0002]

2. Description of the Related Art Conventionally, a permanent magnet type synchronous motor is composed of a tooth portion which is excited by an armature winding inside a hollow cylindrical yoke portion, and a permanent magnet which is opposed to the inside of the tooth portion with a gap. The permanent magnet is provided with a rotor and a plurality of magnetic poles having different polarities are alternately formed in the circumferential direction. By the way, if the air gap magnetic flux density is kept almost constant at the circumferential position of the tip of the tooth with the air gap length kept constant, cogging torque is generated. The air gap magnetic flux density at the center is increased and the air gap magnetic flux density at both ends is reduced to make the air gap magnetic flux density between the tip of the tooth and the permanent magnet into a sinusoidal shape in the circumferential direction. Distributors are disclosed (for example, Japanese Patent Laid-Open No. Sho 63-63).
-162853, JP-A-63-140644).

[0003]

However, in the above-mentioned prior art, the molding die of the permanent magnet is complicated because the thickness of the permanent magnet changes, but the molding die of the permanent magnet that requires a manufacturing process such as sintering is required. When the shape of the mold becomes complicated, it takes a lot of time and effort to obtain the dimensional accuracy after sintering, and the manufacturing cost becomes high. An object of the present invention is to reduce the cogging torque and specify the manufacturing cost of the permanent magnet by specifying the tip shape of the tooth portion.

[0004]

In order to solve the above problems, the present invention provides a hollow cylindrical yoke portion made of a laminated iron core, a plurality of tooth portions projecting inward of the yoke portion, and winding around the tooth portions. And a rotor composed of a cylindrical permanent magnet that is opposed to the tip of the tooth portion with a gap and that has a plurality of magnetic poles of different polarities alternately formed in the circumferential direction. In the provided permanent magnet type synchronous motor, the tips of the teeth are formed so as to project in an arc shape, and the radius of curvature r of the arc is 0.8 W to 1. W when the width of the teeth is W. The range is 1 W.

[0005]

With the above means, the tip of the tooth portion facing the permanent magnet is formed so as to project in an arc shape, and the permanent magnet is formed into a cylindrical shape. Therefore, the permeance distribution between the tooth portion and the permanent magnet is sinusoidal. The wavy distribution can reduce the cogging torque, the molding die for the permanent magnet can be simplified, and the manufacturing cost can be reduced.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing an embodiment of the present invention. In the drawing, 2 which protrudes inside the hollow cylindrical yoke portion 1
A stator 3 formed of a laminated iron core provided with individual tooth portions 2 is formed, and a tip portion 21 of the tooth portion 2 is formed in an arc shape in a protruding direction. An armature coil 4 is wound around the tooth portion 2.
Inside the tooth portion 2, a rotor 6 composed of a cylindrical permanent magnet 5 is rotatably supported so as to face the tip of the tooth portion 2 via a gap G, and a plurality of magnetic poles having different polarities in the circumferential direction. Are formed alternately. Cylindrical permanent magnet 5 and permanent magnet 5
A gap G that changes in a substantially sinusoidal shape along the circumferential direction is formed between the end portion 21 of the tooth portion 2 that is formed in an arc shape so as to project toward. Here, a case where the shape of the tip portion 21 of the tooth portion 2 is determined will be described. The permeance distribution of the air gap when the ratio of the radius of curvature r of the tip portion 21 to the width W of the tooth portion 2 was changed was examined by magnetic field analysis. That is, when the radius of curvature r of the arc of the tip portion 21 of the tooth portion 2 is W, where the width of the tooth portion 2 is W, one having a range of 0.5 W to 1.5 W at 0.1 W pitch is created, and The ratio of the harmonic component of the permeance distribution in the air gap G, where the case where the part has a uniform air gap with the outer circumference of the rotor is 1, was examined. As a result, as shown in FIG. 2, the proportion of harmonic components is small in the range of 0.8 W ≦ r ≦ 1.1 W, which shows that the cogging torque can be reduced most in this range.
Therefore, the radius of curvature r of the arc of the tip portion 21 may be in the range of 0.8 W to 1.1 W, where W is the width of the tooth portion. Since the permanent magnet 5 is formed into a cylindrical shape, the molding die for the permanent magnet is simple and the manufacturing cost is extremely low. The tooth portion 2 is formed in an arc shape, but since the yoke portion 1 and the tooth portion 2 are integrally formed of a laminated iron core, the press die can be easily manufactured, and the dimensional accuracy is increased by the press working. There is no problem because it does not require much effort. In addition, in the present embodiment, the number of tooth portions 2 is 4
However, the number may be increased to two or more such as six and eight, and the number of magnetic poles may be increased according to the number of teeth.

[0007]

As described above, according to the present invention, the permanent magnet is formed in a cylindrical shape, and the tip of the tooth portion facing the permanent magnet is formed in an arc shape so that the tooth portion and the permanent magnet can be formed. Since the permeance distribution between is distributed in a sinusoidal shape,
The cogging torque can be reduced. Further, the shape of the permanent magnet and the molding die are simplified, and there is an effect that an inexpensive permanent magnet type synchronous motor can be provided.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a permeance distribution according to the embodiment of this invention.

[Explanation of symbols]

1 yoke part, 2 tooth part, 21 tip part, 3 stator, 4 armature coil, 5 permanent magnet, 6 rotor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Asanuma 2-1, Kurosaki Shiroishi, Hachimansai-ku, Kitakyushu, Fukuoka Prefecture Yasukawa Electric Co., Ltd.

Claims (1)

[Claims] 1. A stator comprising a hollow cylindrical yoke portion made of a laminated iron core, a plurality of tooth portions projecting inward of the yoke portion, and an armature coil wound around the tooth portion, and a tip of the tooth portion. A permanent magnet synchronous motor having a rotor made of a cylindrical permanent magnet having a plurality of magnetic poles having different polarities alternately formed in the circumferential direction, the distal end portion of the tooth portion Is formed so as to project in an arc shape, and the radius of curvature r of the arc is in the range of 0.8 W to 1.1 W, where W is the width of the tooth portion. .