JPS5966082A - Brush for rotary electric machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a brush for a rotating electric machine having a laminated structure.

Recently, in response to the demand for resource and energy conservation, electric motors have been designed to be smaller and lighter by cutting down the dimensions, but this has resulted in frequent problems caused by rectifying sparks. In other words, the rectification performance of the motor deteriorates despite the reduction in size and weight, which causes sparks to be generated from the brushes, causing abnormal wear of the brushes, rough damage to the commutator, and even flashover. Therefore, in order to solve these drawbacks, brushes are required to have greater spark resistance than conventional brushes. Incidentally, it is well known that the rectifying spark becomes smaller as the contact resistance of the brush increases, so that a spark-resistant brush can be found by bonding a low-resistance brush and a high-resistance brush. To further explain this with reference to FIG. 1, 1 is a brush made of carbon blocks with different resistances bonded together.

If the rotational direction of the rotor having the commutator 2 is the direction of the arrow P, then the low resistance block 1a is located at the front with respect to the direction of one rotation.
It is composed of a high-resistance pro-socket that follows] b. 3
is broken by the lead wire.

However, block 1 with a low resistance of 4000 μΩ・m
a and specific resistance 20.000 μΩ・High resistance block 1 at the mouth
When a brush with the above configuration using B was examined, it was found that a good oxide film was not formed on the surface of the commutator 20, resulting in poor sliding. That is, the laminated brush having the above structure basically has the disadvantage that it is difficult to form a good oxide film, and rectifying sparks cannot necessarily be reduced.

The present invention was made to solve the above-mentioned problems, and its object is to provide a brush for a rotating electric machine having a laminated structure capable of reducing rectifying sparks.

The present invention provides a brush for a rotating electrical machine made by laminating two types of carbon blocks with different resistances, in which a portion of the commutator surface in the axial direction of the rotor on which the low-resistance block slides is connected to the brush with the low-resistance block. The present invention relates to a brush for a rotating electrical machine configured to be larger than a portion on which a high resistance block slides.

In the present invention, the low-resistance block only needs to have the function of transmitting and receiving current to and from the pair of wires on the commutator, and the high-resistance block has the function of suppressing sparks between the brush and the commutator. For this reason, high-resistance blocks are used that have higher contact resistance than low-resistance blocks. Since contact resistance is normally proportional to electrical specific resistance, high-resistance blocks with higher electrical specific resistance than low-resistance blocks are used, but their values are not limited as long as they are determined depending on the application.

It is preferable that the width of the cross section, where the low resistance block and the high resistance block slide together, is 30% of the low resistance block. Brush thickness (distance in rotor rotation direction)
There is no limit to the thickness of the high resistance block as long as it is within the range that suppresses sparks.

In terms of rectification performance, it is preferable for the brush for a rotating electric machine of the present invention to be laminated so that the front side with respect to the rotating direction of the rotor is a low resistance block and the rear side is a high resistance block. In the case of a rotating electric machine that rotates reversibly, it is sufficient to sandwich a low resistance brush and attach high resistance blocks to the front and rear parts. The high-resistance block and the low-resistance block are bonded together by a known method using an adhesive or the like.

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 Figure 2 shows the usage state of the brush 1 having a laminated structure.If the rotation direction of the rotor having the commutator 2 is the direction of the arrow P, then the electrical specific resistance is the front position with respect to the direction of one rotation. 4000
A carbon block 1a with a low resistance of μΩ・m and a high resistance carbon with an electrical specific resistance of 20.000 μΩ・α, which is located downstream of the block 1a in the rotational direction and is bonded with adhesive to both ends of the rotor in the axial direction of the block 1a. It is composed of blocks 1c and 1c. In this case, the total width of block IC is 2 of the width of block 1a.
I was assigned 0 staff.

Example 2 FIG. 3 shows a brush 1 with a laminated structure according to another example of the present invention using carbon blocks of the same phase as in Example 1.
In this case, the high-resistance carbon block 1d is in the shape of an opening, and the vertical and horizontal dimensions are the same as 1a, so the block 1a can be butted against the block 1a and easily bonded to the block 1a in the same way as in the case of manufacturing a conventional laminated brush. I was able to laminate it with the agent.

As a result of applying the brushes of Examples 1 and 2 to a 500W DC motor, the spark number was 4 and the brush life was 2000 hours in the past.

The spark number is reduced to 3 and the brush life is 30
00 hours, a significant improvement.

In the above example, brushes used for a rotor that rotates in only one direction are shown, but for rotating electric machines that rotate reversibly, blocks with high resistance and blocks with low resistance in the rotation direction of the rotor are shown. As a result of using brushes attached to the front and back sides, the same effect as above was obtained.

The sliding state of the brush with the above configuration in this embodiment depends on the performance of the large block 1a in the part that slides on the commutator surface, and the sliding part in which both the block 1a and the block IC or 1d slide. Because it is small, FIL (the influence of the condition of the iron film is small, preventing the brush from sliding poorly, and rectifying sparks are reduced by the high-resistance block) can improve the rectifying performance of the rectifier.

As described above, the brush according to the present invention may suffer from sliding failure.

[Brief explanation of drawings]

Figure 41 is a perspective view showing how the conventional laminated brush is used.
FIG. 2 is a perspective view showing how a laminated brush according to one embodiment of the present invention is used, and FIG. 3 is a perspective view showing how a laminated brush according to another embodiment of the present invention is used. Explanation of symbols l... Brush 1a, 1b, 1c, 1d - Block 2...
Commutator 3...Lead wire 1st section 2 Figure

Claims (1)

[Scope of Claims] 1. In a brush for a rotating electrical machine made by laminating two types of carbon blocks with different resistances, a portion on which the low resistance block slides on the commutator surface in the axial direction of a rotor. A brush for a rotating electric machine configured so that the core is larger than the part where both the low resistance block and the high resistance block slide. 2. The brush for a rotating electric machine according to claim 1, wherein the forward side in the rotational direction of the rotor is a low-resistance block and the rearward side is a high-resistance block. 3. A brush for a rotating electric machine according to claim 1 or 2, wherein high resistance Glocks are provided at both ends in the +1q11 direction of the rotor of the low resistance block.