JPH0424778Y2 - - Google Patents

Description

[Detailed explanation of the idea] (Industrial application field) The present invention relates to a brush holding device for an electric motor.

(Prior Art) FIG. 3 shows a cross-sectional view of a conventional brush holding device. In the figure, 1a and 1b are an anode brush and a cathode brush, 2
Reference numeral 3 designates a brush holder that accommodates both brushes 1a and 1b, respectively, and 3 a spring that presses the brushes 1a and 1b against the commutator 5. 4 is a base for fixing the brush holder 2, and 6 is an anode brush 1a.
This is an insulating plate for insulating the base 4 from the base 4. A rear bracket 7 fixes the base 4 of the brush holder 2, and is fixed with screws 8. In addition, 9 is an armature, 10 is a coil of the armature 9, 11 is a magnet that generates magnetic flux, and 12 is a bearing that supports the shaft of the armature 9 on the rear bracket 7.

In the conventional brush holding device configured as described above, the brushes 1a and 1b are pressed against the commutator 5 by the spring 3, and form an electric circuit with the coil 10. When current flows through this circuit, a rotational force is generated in the armature 9 due to the action with the magnet 11 that excites the motor.

(Problem to be Solved by the Invention) In the conventional brush holding device configured as described above, the spring 3 that presses the brushes 1a and 1b against the commutator 5 is heated once to its yield stress before being put into the holder 2. The material was compressed to an almost intimate state (full compression) exceeding 100 mL, straining the crystals of the material and strengthening it (hereinafter referred to as pressure hardening), and after improving its strength, it was incorporated into the holder 2. There was a problem that assembly was time consuming.
Further, in the brush holder of the conventional brush holding device, when the brush is placed into the holder following the coil spring and assembled into the electric motor, the brush may be pushed into the holder more than necessary. If the brush is pushed into the holder more than necessary, the coil spring may be subjected to additional compression forces from its fully compressed or sealed state, which can cause the coil spring to buckle or twist within the holder, damaging the spring. There was a problem that I sometimes let it happen.

The purpose of the present invention was to solve these conventional problems.By incorporating a brush holding device into an electric motor, the spring is work hardened and strengthened. It is an object of the present invention to provide a brush holding device that prevents damage to a spring without applying an unnecessarily compressive force to the spring.

(Means for Solving the Problems) The brush holding device of the present invention is provided with a stopper on the inner surface of the brush holder to prevent the brush from entering the bottom side of the holder from a predetermined position, and the stopper and the bottom of the brush holder are connected to each other. The spacing between the brush and the brush is set to be shorter than the compressed length reaching the yield point of a coil spring having one end in contact with the bottom of the holder and the other end in contact with the end of the brush.

(Function) According to the brush holding device of the present invention, when assembling the brush holding device into an electric motor, a coil spring is inserted into the brush holder, and then a brush is inserted. When assembling this brush holding device into an electric motor, the brush is pushed into the holder against the pressing force of the coil spring until it contacts the stopper and attached to the specified location, and then the hand that is pushing the brush is released and the end face of the brush is removed. Contact with commutator. As a result, the coil spring is compressed within the distance between the bottom of the holder and the stopper by pushing the brush until it comes into contact with the stopper, and this compressed length is shorter than the compressed length that reaches the yield point of this coil spring. The coil spring is work hardened and has improved strength.

(Example) Hereinafter, the brush holding device of the present invention will be described with reference to an example shown in the drawings. FIG. 1 shows a sectional view of a brush holding device according to an embodiment of the present invention;
a is a stepped portion formed on the inner wall surface of the brush holder 2, and the brush 1 accommodated in the brush holder 2 is
Since the brushes a and 1b come into contact with the stepped portion 2a and are prevented from further entering the brush holder 2, the stepped portion 2a functions as a stopper. On the other hand,
The coil spring 3 that presses the brushes 1a and 1b against the commutator 5 is arranged in the brush holder 2 so that one end is in contact with the bottom of the brush holder 2 and the other end is in contact with the rear end of the brushes 1a and 1b. By this coil spring 3, the brushes 1a, 1b
is pressed against the commutator 5. At this time, the stepped portion 2a
The length to the bottom of the brush holder 2, that is, the depth, is set shorter than the compression length of the coil spring 3 that reaches its yield point. Initial length of brushes 1a and 1b or brush holder 2 and commutator 5
The distance between the brushes 1a and 1b is such that when the brush holding device is assembled into the motor, the brushes 1a and 1b are not in a position where they are completely in contact with the stopper stage 2a, but in a position slightly closer to the commutator 5 side. is set to . In other words, the tip of the coil spring 3 comes into contact with the brushes 1a and 1b at a point where it slightly protrudes toward the commutator side beyond the step 2a, and there is a slight play or margin to the rear with respect to the brushes. It means giving. Note that the other configurations are the same as the conventional brush holding device shown in FIG.

According to the brush holding device of the embodiment of the present invention configured as described above, when assembling the brush holding device,
The coil spring 3 is put into the brush holder 2, and then the brushes 1a and 1b are put into the holder 2. When assembling this brush holding device into an electric motor, when fixing the brush holder 2 in a predetermined position while pushing the brushes 1a and 1b into the brush holder 2, push the brushes until they come into contact with the stepped portion 2a, which is a stopper. The coil spring 3 is compressed to the distance between the stepped portion 2a and the bottom of the holder 2. This stepped portion 2a and the holder 2
Since the distance between the coil spring 3 and the bottom of the coil spring 3 is set to be slightly shorter than the compression length when the coil spring 3 is in a close contact state that causes work hardening, the coil spring 3 is compressed until it reaches its yield point, and as a result, the coil spring 3 is compressed until it reaches its yield point. The spring 3 is work hardened, that is, compressed to exceed its yield stress, thereby straining the crystals of the material and strengthening it, improving its strength. In this way, the coil spring can be work-hardened to increase its strength by utilizing the process of assembling the brush holding device into the electric motor, so that the assembly work can be easily performed.

Also, if you try to push the brushes 1a, 1b into the brush holder 2 more than necessary, the brushes 1a, 1b
Since b comes into contact with the step part 2a which is the stopper,
It is possible to avoid compressing the coil spring 3 beyond full compression, and damage to the spring 3 can be prevented.

In the above embodiment, the brush 1 is arranged in the circumferential direction of the commutator 5.
Although the example in which the commutators a and 1b are arranged has been described, as shown in FIG. Even if they are in contact with each other, the same effect as in the above embodiment can be obtained.

Incidentally, the brush holder 2 and the rear bracket 7 may be integrally molded from resin, and a wire-wound type may be used instead of a magnet for exciting the electric motor.

(Effect of the invention) As explained above, according to the brush holding device of the invention, a brush stopper is provided on the inner wall of the brush holder, and the distance between the stopper and the bottom of the brush holder is adjusted to reach the yield point of the coil spring. By setting the length shorter than the compression length, the coil spring can be work-hardened and strengthened simply by incorporating the brush holder into the motor, and the coil spring will not be compressed more than necessary when pushing the brush into the brush holder. Therefore, it is possible to provide a highly reliable brush holding device without causing damage due to buckling or twisting of the coil spring.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a brush holding device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of another example of the brush holding device, and FIG. 3 is a cross-sectional view of a conventional brush holding device. 1a, 1b...Brush, 2...Brush holder, 2a...Step, 3...Coil spring, 5
... Commutator, 7 ... Rear bracket, 9 ... Armature, 13 ... Face type commutator. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims for Utility Model Registration] (1) In order to press one end of the brush housed in the brush holder against a commutator of an electric motor, a pressing force is applied to the other end of the brush by a coil spring disposed inside the brush holder. In the brush holder, the brush holder is provided with a stopper on the inner surface for preventing the brush from entering the bottom side of the holder from a predetermined position, and the distance between the stopper and the bottom of the brush holder is such that one end is A brush holding device, characterized in that the brush holding device is set to be shorter than the compressed length reaching the yield point of the coil spring whose other end is in contact with the bottom of the holder and with the other end of the brush. (2) The brush holding device according to claim 1, wherein the commutator is a gaffe-eight commutator that the brush comes into contact with.