JP2000262026A - Axial direction gap type micromotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an axial direction gap type micromotor which can suppress cogging torque and reduce torque fluctuation rate. SOLUTION: Stator teeth 11 and 21 of an axial direction gap type micromotor, having a rotor 3 comprising a disc-type permanent magnet which is magnetized in the axial direction so as to position the polarities N and S alternately in the circumferential direction and has a plurality of pole pairs on both its sides and has a 1st stator 1 and a 2nd stator 2, which are placed on both the sides of the rotor 3 so as to face each other vertically with a gap therebetween and have the plurality of teeth 11 and 21 respectively and armature windings 4 wound on the stator teeth 11 and 21 are formed into involute curves as viewed in the axial direction of the micromotor. If currents are applied to the armature windings 4 of the respective stators, the rotor 3 rotates smoothly even if the rotation angle is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to, for example, consumer OA
The present invention relates to an axial gap type micromotor having a permanent magnet and used for a micromotor of a device or an industrial FA device, and more particularly to a device for reducing cogging torque.

[0002]

2. Description of the Related Art Conventionally, an axial gap type micromotor used for a micromotor of OA equipment, FA equipment and the like is as shown in FIG. In the figure, an axial gap type micromotor is magnetized in the axial direction such that polarities of N and S are alternately located in a circumferential direction, and a disk-shaped permanent magnet having a plurality of magnetic pole pairs formed on both surfaces. Rotor 3 consisting of magnet
And a first stator 7 and a second stator 8 which are opposed to both surfaces of the rotor 3 via a gap and have a plurality of stator teeth 71, 81 each having a sector shape. The wound armature winding 9, the shaft 5 vertically disposed on the surface of the rotor 3, the first stator 7 and the second
A ring-shaped frame 6 for connecting the two stators disposed between the stators 8 and a bearing 51 are provided.

[0003]

However, in the prior art, each of the stators 7 and 8 has its own stator teeth 71 and 8 respectively.
Because the shape of 1 is fan-shaped and the radial length of the tooth is narrow,
The number of turns of the armature winding 9 wound around one tooth portion cannot be increased, and the electromagnetic gap between the wound armature windings 9 increases. As a result, each time the rotation angle of the rotor 3 changes, the gap suction force in the axial direction fluctuates, and the cogging torque between the first stator 7 and the second stator 8 sandwiching the rotor 3 increases, and the torque fluctuation rate also increases. There was a problem. Accordingly, an object of the present invention is to provide an axial gap type micromotor capable of suppressing the occurrence of cogging torque and reducing the torque fluctuation rate.

[0004]

In order to solve the above-mentioned problem, the present invention according to claim 1 is characterized in that the magnets are magnetized in the axial direction so that the polarities of N and S are alternately arranged in the circumferential direction. A rotor composed of disk-shaped permanent magnets each having m (m is an integer) magnetic pole pairs is vertically opposed to both surfaces of the rotor with a gap therebetween, and n (n is an integer) respectively
A first stator and a second stator having a plurality of stator teeth and an armature winding wound around the stator teeth;
A ring-shaped frame connecting the two stators disposed between the first stator and the second stator, wherein the stator teeth are viewed from the axial direction of the motor. , Formed in an involute curve. According to a second aspect of the present invention, in the axial gap type micromotor according to the first aspect, the first stator and the second
Position the stator teeth of the stator 18
It is arranged by being shifted by 0 / (m × n) degrees. According to the above-described means, the armature winding is wound around each stator tooth formed in the involute shape, so that the number of turns of the armature winding wound per tooth can be increased. The electromagnetic gap between the turned armature windings can be reduced. As a result, the gap suction force in the axial direction does not fluctuate every time the rotation angle of the rotor changes, so that the cogging torque can be reduced between the first stator and the second stator with the rotor interposed therebetween. Can also be reduced.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1A and 1B show an axial gap type micromotor according to a first embodiment of the present invention. FIG. 1A is a cross-sectional view showing a motor configuration, and FIG. 1B is a top view of a stator. The same components as those in the related art are denoted by the same reference numerals, and description thereof will be omitted. Only different points will be described. In the figure, the points different from the conventional one are as follows. That is,
1 is a first stator, 2 is a second stator, 11 and 21 are stator teeth provided on each of the stators 1 and 2, and 4 is an armature winding wound around each of the stator teeth 11 and 21. The stator teeth 11, 21 are formed in an involute curve when viewed from the axial direction of the motor. Here, the following method is used to machine the stator teeth 11, 21 into an involute curve. FIG. 2 is a partial cross-sectional view of a stator tooth portion processed into an involute curve shape in FIG. As the involute curve A unwinds the virtual yarn C wound around the virtual circle B, the ends of the virtual yarn C are turned counterclockwise from the position A in the figure by 30 °, 60 °, 90 °, 120 °.
In other words, the curve is drawn by moving in the order of b → c → d → e in the figure. The hatched portions surrounded by the involute curves shown in FIG. 2 are the stator teeth 11 and 21, and the armature winding 4 is wound around the stator teeth 11 and 21 as shown in FIG.
Each of the stators 1 and 2 as shown in FIG. Next, the operation will be described. Since each of the stators 1 and 2 had a configuration in which the circumferential electromagnetic gap between the stator teeth 11 and 21 was reduced, a current was applied to the armature winding 4 wound around each of the stator teeth 11 and 21. At this time, the rotor 3 rotates smoothly without changing the gap suction force in the axial direction every time the rotation angle changes between the first stator 1 and the second stator 2. Next, a second embodiment of the present invention will be described. FIG. 3 is a circumferential development of a rotor and a stator showing a second embodiment of the present invention. In the figure, a rotor 3 composed of permanent magnets having m = 6 magnetic pole pairs, a first stator 1 having n = 4 stator teeth 11a, 11b, 11c and 11d, and four rotors are also provided. Stator teeth 21a, 2
The example of the motor provided with the 2nd stator 2 which formed 1b, 21c, and 21d is shown. That is, the difference from the first embodiment is that the positions of the stator teeth 11 and 21 of the first stator 1 and the second stator 2 are shifted from each other by 180 in the circumferential direction.
/ (M × n) degrees, and the position shift angle at this time is α in the figure. By doing so, the cogging torque generated between the first stator 1 and the second stator 2 with the rotor 3 interposed therebetween can be effectively canceled. The operation is basically the same as that of the first embodiment, and the description is omitted. Next, the torque fluctuation rate of the axial gap type micromotor according to the present invention will be described. Among the embodiments of the present invention, a micromotor according to the first embodiment was actually manufactured on a trial basis, and its effect was confirmed by a test. FIG. 4 is a graph showing a comparison between the present invention and a conventional torque fluctuation rate. As shown in the figure, it was found that the value of the conventional torque fluctuation rate was reduced from 5% to 2% in the present invention, and the torque fluctuation rate was reduced. Therefore, the shape of each stator tooth portion is involute, and the armature winding is wound around the stator tooth portion formed on the involute curve, so that the armature is wound around one tooth portion. The number of turns of the winding can be increased, and the electromagnetic gap between the wound armature windings can be reduced.
As a result, each time the rotation angle of the rotor changes, the gap suction force in the axial direction does not change, and
The cogging torque between the stator and the second stator can be reduced, and thereby the torque fluctuation rate can be reduced.

[0006]

As described above, according to the present invention, since the stator teeth are formed as involute curves, the occurrence of cogging torque occurring between the stators with the rotor interposed therebetween is suppressed, and the torque fluctuation rate is reduced. There is an effect of obtaining an axial gap type micromotor capable of performing the above. In addition, since the positions of the stator teeth of each stator are shifted from each other in the circumferential direction, the cogging torque can be more effectively canceled.

[Brief description of the drawings]

FIG. 1 shows an axial gap type micromotor according to a first embodiment of the present invention, in which (a) is a cross-sectional view showing a motor configuration;
(B) is a top view of the stator.

FIG. 2 is a partial cross-sectional view of a stator tooth portion processed into an involute curve in FIG. 1;

FIG. 3 is a circumferential development view of a rotor and a stator showing a second embodiment of the present invention.

FIG. 4 is a graph showing a comparison between the present invention and a conventional torque fluctuation rate.

FIG. 5 is a conventional axial gap type micromotor,
FIG. 3A is a cross-sectional view illustrating a motor configuration, and FIG. 3B is a top view of a stator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 first stator 2 second stator 11 stator teeth 21 stator teeth 11a, 11b, 11c, 11d permanent magnets 21a, 21b, 21c, 21d permanent magnet 3 rotor 4 armature winding 5 shaft 6 frame A involute curve B Virtual circle C Virtual thread

Claims (2)

[Claims] 1. A disk-shaped permanent magnet which is magnetized in the axial direction so that polarities of N and S are alternately positioned in a circumferential direction, and has m (m is an integer) magnetic pole pairs on both surfaces. And n (n is an integer) stator tooth portions and armature windings wound around the stator tooth portions, each of which is vertically opposed to both surfaces of the rotor with a gap therebetween. An axial gap type micromotor comprising: a first stator and a second stator; and a ring-shaped frame that connects the two stators disposed between the first stator and the second stator. Is formed in an involute curve when viewed from the axial direction of the motor. 2. The position of the stator teeth of the first stator and the second stator is set to 180 / (m
× n) The axial gap type micromotor according to claim 1, which is displaced by degrees.