JPH04344149A - Commutator for motor - Google Patents

Abstract

PURPOSE:To eliminate drop of brush pieces into a slit between commutator segments and to prevent generation of a vibration in a commutator for a motor, having a plurality of brush pieces branched from an end of a brush. CONSTITUTION:A commutator 6 made of a plurality of commutator segments 3, and a brush 5 made of brush pieces 4 in contact with the segments 3 divided at its end into plurality, are provided. A skew angle is formed at the slit 2 between the segments 3, and the angle is so set that the pieces 4 are simultaneously brought into contact with the peripheries of the adjacent segments 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor commutator that can eliminate mechanical vibrations.

0002

[Prior Art] Fig. 10 shows an example of a commutator of a conventional motor.
, as shown in FIG. In FIG. 10, the cylindrical motor case 21 has an open right end, and a side plate 24 is attached to this opening. Motor case 2
1 and the center of the side plate 24 are fitted with bearings 25, 25, and these bearings 25, 25 rotate the shaft 26.
is rotatably supported.

A shaft 2 is provided on the inner peripheral surface of the motor case 21.
A magnet 22 is attached at a position facing the rotor portion 27 attached to the center portion of the magnet 6 with a gap therebetween. A terminal 23 is attached to the outside of the side plate 24,
It is connected to a brush 29 inside the motor. shaft 26
has a rotor section 27 in its center and a commutator 28 on its side.
is attached to the rotor section 2 together with the shaft 26.
7 and commutator 28 are adapted to rotate together. The rotor portion 27 has a plurality of salient poles, and a coil is wound around each salient pole. A brush 29 is in contact with the commutator 28.

FIG. 11 shows an enlarged view of the contact area between the commutator 28 and the brush 29. In FIG. 11, a damper 32 is attached to the brush 29 to prevent vibration. A plurality of commutator segments 31 are provided on the surface of the commutator 28 in contact with the brushes 29, and each commutator segment 31
A slit 30 is provided therebetween parallel to the line of contact between the brush 29 and the commutator segment 31. shaft 2
When the commutator 28 rotates together with the commutator 28, the commutator segments 31 that the brushes 29 contact are sequentially switched, thereby switching the current flowing through the coils of the rotor section 27.

[0005]

[Problems to be Solved by the Invention] In the conventional DC motor as described above, the commutator 28 rotates and the brush 29
When contacting the next commutator segment 31, there is a slit 30 between the commutator segments 31, so α
A step as shown in FIG. 2 is generated, and the brush 29 falls into this step, causing the brush 29 to vibrate greatly. brush 29
vibrations lead to mechanical noise and arcing. When an arc occurs, it causes electrical noise that adversely affects other electronic components, accelerates wear of the brushes and commutator due to arc destruction, and generates powder due to reaction with the internal atmosphere, which can significantly reduce the characteristics and life of the motor. There was a problem of lowering the

The damper 32 described with reference to FIG. 11 is used to eliminate the vibration of the brush 29, but this does not eliminate the cause of the vibration of the brush 29 itself.
It did not lead to a fundamental solution to the problem.

[0007] As a method for preventing the vibration of the brush 29, Japanese Patent Laid-Open No. 1-222642 discloses a technique in which a skew angle is provided to the slits of the commutator and the skew angle is set to 3 to 20 degrees. There is. The technique described in the above publication sets the skew angle based on the overall width dimension of the brush 29, so it is effective only when there is only one brush piece at the tip of the brush, that is, when there is no branching. If the tip of the brush is branched and made up of multiple brush pieces, the line of contact between the brush and the commutator segment will fall into the slit, which will not help eliminate vibration.

[0008] The present invention has been made to solve these problems.In a brush in which the tip of the brush is branched and composed of a plurality of brush pieces, each brush piece is connected to a commutator segment. To provide a motor commutator which prevents brushes from vibrating by preventing them from falling into slits between them.

[0009]

[Means for Solving the Problems] A commutator for a motor according to the present invention includes a commutator composed of a plurality of commutator segments;
It has a brush whose tip part is divided into a plurality of brush pieces and comes into contact with the commutator segments, and the slit between the commutator segments has a skew angle, and the skew angle is different from that of each brush piece. is an angle that allows simultaneous contact with the circumferential surfaces of mutually adjacent commutator segments.

0010

[Operation] As the commutator rotates, each brush piece switches from contacting one commutator segment to contacting the next adjacent commutator segment. At this time,
A skew angle is attached to the slit between the commutator segments, and this skew angle is an angle that allows each brush piece to contact the circumferential surface of adjacent commutator segments at the same time. The pieces do not fall into the slits between the commutator segments and no vibrations occur.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a motor commutator according to the present invention will be described with reference to FIGS. 1 to 9. In FIGS. 1 to 5, the brush 5 is composed of a brush base 1 and a plurality of brush pieces 4 at the tip thereof. The brush piece 4 is in contact with a commutator segment 3 on a commutator 6 that rotates together with the motor shaft, and supplies the current flowing through the commutator segment 3 to the coils of the rotor part of the motor. As is well known, the commutator 6 has a plurality of commutator segments 3, and each commutator segment 3 is located on a cylindrical surface centered on the central axis of the motor shaft. A slit 2 for current switching is provided between each commutator segment 3 on the surface of the commutator 6.

If the slit 2 is parallel to the line of contact between the commutator segment 3 and the brush piece 4, the brush piece 4 falls into the slit 2 and vibrates as explained with reference to FIG. Commutator segment 3
The skew angle is set obliquely to the contact line between the brush piece 4 and the brush piece 4.

Next, FIG. 3 shows the setting of the above skew angle.
~Explained with reference to FIG. When setting the skew angle of the slit 2 between the commutator segments, if it is set based on the width dimension of the entire brush, if the tip of the brush is branched into multiple branches, vibrations will occur as described in the above publication. It is not possible to prevent the occurrence of In order to prevent brush vibration from occurring, the skew angle of the slit 2 should be set based on the width dimension of each brush piece 4 at the tip of the brush.

In FIGS. 3 and 4, when the skew angle of the slit 2 is θ, the width of the slit 2 is a, and the width of each brush piece 4 is b, θ≒tan￣ 1(a/ b) Find the skew angle θ by:

Now, suppose that the skew angle θ is as shown in FIG.
If is smaller than the value determined as above, the contact line 14 between the commutator 6 and the brush piece 4 will be included in the slit 2, and the brush piece 4 will fall into the slit 2 and generate vibration. , there is no effect of adding a skew angle to slit 2.

On the other hand, as shown in FIGS. 7 and 8,
If the skew angle θ is equal to or larger than the value determined by the above formula, each brush piece 4 can simultaneously contact the circumferential surfaces of the commutator segments 3, 3 adjacent to each other. , each brush piece 4 does not fall into the slit 2, and vibration of the brush pieces 4 and the brush 5 as a whole can be prevented from occurring. Therefore, the skew angle θ is θ≧
Set so that tan￣ 1 (a/b).

Note that, as shown in FIG. 8, the skew angle θ is ta
If n￣ is larger than 1 (a/b), brush vibration can be prevented as described above, but one brush piece 4 may come into contact with both adjacent commutator segments 3, 3. There is a problem that the efficiency of the rectifying action decreases because the time spent in the rectifier increases.

In this respect, as shown in the example of FIG.
If the skew angle θ is set to 1 (a/b), vibration of the brush can be prevented and the efficiency of the rectifying action is also good, so it is desirable to set the skew angle θ to such a value.

Next, another embodiment of the present invention shown in FIG. 9 will be described. In the embodiments described so far, the slits between the commutator segments extend in a straight line, but in the embodiment shown in FIG. 9, the slits 12 between the commutator segments 13, 13 are formed in a wave shape. Two brush pieces 4 are arranged within one pitch of the wavy slit 12, and one brush piece 4 is arranged to overlap one inclined part of the slit 12. Further, when the width of the slit 12 is a and the width of each brush piece 4 is b, the angle of one inclined part of the slit 12 where each brush piece 4 overlaps, that is, the skew angle θ is Configure as in the example.

In the embodiment shown in FIG. 9 as well, each brush piece 4 has commutator segments 13, 13 adjacent to each other.
Since each brush piece 4 can contact the circumferential surface of the brush at the same time, each brush piece 4 will not fall into the slit 12, and vibration of the brush pieces 4 and the brush 5 as a whole can be prevented from occurring.

In the embodiment shown in FIG. 9, the inflection point of the wavy slit 12 is square, but this inflection point may be arcuate.

[0022]

According to the present invention, in a commutator for a motor having a brush whose tip end is made up of a plurality of brush pieces, a skew angle is provided in the slit between the commutator segments, and the skew angle is set at an angle that allows each brush piece to simultaneously contact the circumferential surface of the adjacent commutator segment, eliminating the cause of brush vibration itself and eliminating the generation of arcs and electrical noise caused by brush vibration. It is possible to solve various problems such as Furthermore, since there is no need to use a damper to damp vibrations generated in the brush, there is also the effect that the number of parts can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of a commutator for a motor according to the present invention.

FIG. 2 is a cross-sectional front view of the same as above.

FIG. 3 is an enlarged plan view of the main parts of the embodiment.

FIG. 4 is an enlarged plan view of the portion surrounded by a circle 10 in FIG. 3.

FIG. 5 is a perspective view of the above embodiment.

FIG. 6 is a plan view showing an example of a skew angle of a slit.

FIG. 7 is a plan view showing an example of the skew angle of the slit according to the above embodiment.

FIG. 8 is a plan view showing another example of the skew angle of the slit according to the above embodiment.

FIG. 9 is a plan view showing another embodiment of a commutator for a motor according to the present invention.

FIG. 10 is a partially sectional plan view showing an example of a conventional motor.

FIG. 11 is an enlarged front view of the commutator portion of the motor.

FIG. 12 is a perspective view of the commutator portion of the same as above.

FIG. 13 is a plan view of the same as above.

FIG. 14 is an enlarged front view of the same as above.

[Explanation of symbols]

2 Slit 3 Commutator segment 4 Brush piece 5 Brush

Claims (1)

[Claims] 1. A commutator comprising a plurality of commutator segments, and a brush having a tip portion divided into a plurality of brush pieces that contact the commutator segments, wherein A commutator for a motor, characterized in that the slit has a skew angle, and the skew angle is an angle that allows each brush piece to simultaneously contact the circumferential surface of adjacent commutator segments.