JP3288175B2 - Carbon brush for electric machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon brush for an electric machine which is brought into sliding contact with a commutator in a generator, a commutator motor or the like.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication Nos. Hei 5-38099 and Hei 5-182733 disclose brushes for electric machines.
As shown in the above publication, a brush body whose tip is worn by contact with a commutator, a lead wire connected to the rear end of the brush body, and a brush body which abuts on the rear end of the brush body. There is a brush for an electric machine including a compression spring for urging a brush body toward the commutator. The brush body is generally a carbon-based brush, and is obtained by mixing a binder made of synthetic resin or the like with carbon and compressing and solidifying the same.
If necessary, a material obtained by sintering the compressed and solidified material at a low or high temperature, or a material obtained by mixing a powder of a good conductive metal with carbon and sintering the material is employed. An electric machine brush employing such a carbon-based brush body is referred to as an electric machine carbon brush, and the brush body generally employs a resistive rectifier to suppress sparks generated when the brush comes into sliding contact with a commutator. Because of the need to increase the size, a type having a high electric resistance is used.

[0003]

By the way, in a carbon brush for an electric machine of the above-mentioned type (hereinafter simply referred to as a carbon brush), when a brush body having a large electric resistance is used as the brush body, There is a problem that the rectification efficiency is reduced due to a large resistance loss of the brush body, and a problem that heat generation due to the resistance loss causes thermal deterioration of the brush body.

As a means for solving these problems, the above-mentioned publication discloses that the brush body is composed of a carbon-based main part and a good conductive part made of an electric conductor higher than the main part. A carbon brush formed by connecting a lead wire to a conductive portion is disclosed. In the carbon brush, when a good conductive portion is formed in a carbon-based main portion of the brush body, the total electrical resistance of the brush body is small, and the brush body is entirely made of a low-resistance good conductive material. There is an advantage that heat generation due to resistance loss can be suppressed while maintaining a good rectification efficiency without a significant decrease in the rectification resistance as compared with the above. Also, the latter publication discloses a carbon brush in which a good conductive metal coating is applied to the outer peripheral surface of the carbon-based brush main body except for the tip end surface. In the carbon brush, current flows from both the lead wire and the metal coating to the brush body, so that the total electric resistance of the brush body is reduced, and the same effect as the carbon brush disclosed in the former publication is obtained. There is an advantage of playing.

However, in the former carbon brush, the brush main body has a special structure, and in order to form the brush main body, a hole having a predetermined length is provided in a longitudinal direction in a carbon-based main body to obtain a good conductive property. Filled with metal powder and solidified,
The lead wire must be joined to the good conductive part formed by filling and solidifying in this way, which is extremely troublesome in manufacturing, and the good conductive part and the main part thus formed have thermal expansion. Therefore, there is a problem that the main part is damaged due to the difference in thermal expansion. In order to cope with this, there is a problem that a metal powder having a special shape must be adopted as a material constituting the good conductive portion. In the latter carbon brush, electroless plating must be applied to the outer peripheral surface of the brush main body, and in this case also, there is a serious problem in manufacturing.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a carbon brush which has at least the same functions and effects as those of both carbon brushes and can solve the above-mentioned problems.

[0007]

SUMMARY OF THE INVENTION According to the present invention, carbon or carbon is mainly used and its tip is worn by contact with a commutator.
A brush body having a rectangular cross-section having a predetermined length, a lead wire connected to a rear end of the brush body, and a compression contacting the rear end of the brush body to urge the brush body toward the commutator. In a carbon brush for an electric machine provided with a spring, in a longitudinal direction of an opposite side surface of the brush body ,
At least one pair of grooves are formed, and at least a pair of elastically deformable arms that are arranged side by side at predetermined intervals and a connecting part that connects these arms to each other at a rear end.
A fitting member made of a conductive material is provided;
From the rear end of the brush body, and
Compression spring between the portion and the rear end face of the brush body
And connecting the connecting portion to the lead wire,
The tip of the arm section is elastically brought into contact with the groove section.
And the brush body into which the fitting member has been fitted is held.
And the brush body can be moved in the longitudinal direction
It is characterized by having done.

[0008]

In [Action and Effect of the Invention] carbon brush thus configured, the lead wire to the brush body, the current from the highly conductive terminal is resiliently contact the outer surface of the brush body flows that And the total electrical resistance of the brush body decreases. As a result, compared to the case where the brush body is made of a low-resistance good conductive material, the rectification resistance does not significantly decrease, and heat generation due to resistance loss can be largely suppressed while maintaining good rectification efficiency. Things.

[0009] In the carbon brush, with the can employ conventional brush body as the brush body, the good conductivity of the terminals of the fitting member to the outer surface of such a brush body to resiliently abut Since it is only a small amount, it can be easily manufactured without any troublesome work, and there is no manufacturing problem as seen in the above-described conventional carbon brushes.

[0010]

Examples of EXAMPLES Hereinafter the present invention will be described with reference to the drawings, the carbon brush of the present invention is shown in FIGS. 1 to 3
ing. The carbon brush 20 includes a brush body 21 and
Lead wire 22, holder 23, compression spring 24
And a fitting member 25. In the carbon brush 20, the brush body 21 has a rectangular shape with a predetermined length, and employs an ordinary brush body formed by mixing a binder made of a synthetic resin or the like with carbon and compressing and solidifying the mixture. In the brush body 21, a pair of grooves 21a, 21b is formed on each of the upper and lower surfaces. Each groove 21a,
21b has a predetermined depth, and extends from the front end to the rear end.
Extending in the direction . A lead wire 22 is joined to the rear end of such a brush body 21. The holder 23 has a rectangular section with an open end.

The fitting member 25 includes a pair of upper and lower arms 25a and 25b which are arranged side by side at predetermined intervals, and a connecting portion 2 which connects the two arms 25a and 25b to each other at a rear end.
5c, and is made of brass, which is a good conductive material. The space between the two arms 25a, 25b is formed to be slightly smaller than the vertical thickness of the brush body 21, and the respective arms 25a, 25b
Is formed in a semicircular shape protruding inward. Each of the arms 25a and 25b is formed so as to be elastically deformable in the vertical direction with each end of the connecting portion 25c as a fulcrum.

The fitting member 25 is fitted from the rear end side of the brush body 21 to the outside thereof. In the fitted state, the rear end of the lead wire 22 is connected to the connecting portion 25c, and A compression spring 24 is interposed between 25c and the rear end surface of the brush body 21. Also, the fitting member 25
Each arm 25a of, 25b is the grooves 21a of the brush body 21, and located within 21b, and elastically abuts and constitute terminals to the bottom of the tips of the tip 25d are respective grooves 21a, 21b ing. Brush body 21, have been fitted in the holder 23 in a state where the fitting member 25 is fitted, the length
It can be moved in the hand direction. And the brush body
21 is resiliently <br/> to abut the tip commutator C is assembled to the motor.

The carbon brush 20 constructed as described above
During the operation of the electric motor , current flows through the brush body 2 through the lead wire 22 in the brush body 21 of the carbon brush 20.
1 flows from the rear end to the commutator C via the front end, and the arms 25a, 25b, 25d of the fitting member 25.
From the brush body 11 to the commutator C
Flows to For this reason , the total electric resistance can be reduced as compared with the case where all the current flows from the rear end to the commutator C via the front end of the brush main body 21, and the resistance loss of the current in the brush main body 21 can be reduced. The operation efficiency of the brush body 21 can be suppressed, and the heat generation due to the resistance loss can be suppressed, and the thermal degradation of the brush main body 21 can be prevented.

[0014] In this carbon brush 20, the brush together with the can employ conventional brush body as the body 21, such brush body 21 of the outer surface fitting the fitting member 25 engages with the arm 25a , 25b
Because you are configured to abut the tip to elastically, the carbon brush 20 can be easily manufactured without requiring a troublesome work, solve the conventional problems in manufacturing such seen in each carbon brush can do.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional plan view of a carbon brush of the present invention.

FIG. 2 is a longitudinal sectional side view of the carbon brush taken along a line AA in FIG. 1;

FIG. 3 is a front view of the carbon brush as viewed in the direction of arrow B in FIG. 2;

[Explanation of symbols]

 20 → Carbon brush 21 → Brush body 22 → Lead wire 23 → Holder 24 → Compression spring 25 → Mating member 25a, 25b → Arm part (terminal) 25c → Connecting part

Claims (1)

(57) [Claims] 1. A brush body having a rectangular cross section with a predetermined length, which is mainly made of carbon or carbon and whose tip is worn by contact with a commutator, and a lead wire connected to a rear end of the brush body. And a carbon brush for an electric machine comprising a compression spring that abuts on a rear end of the brush body and urges the brush body toward the commutator .
Form at least a pair of grooves in the longitudinal direction of the opposing side surfaces
And a conductive material including at least a pair of elastically deformable arms arranged side by side at predetermined intervals and a connecting portion connecting the arms at a rear end thereof. A mating member, and the mating member is connected to a rear end of the brush body.
And the rear end face of the brush body with the connecting portion
The compression spring is interposed between the
While connecting to the lead wire,
The fitting member is provided so as to resiliently contact the groove, and the fitting member
Fit the fitted brush body into the holder and
A carbon brush for an electric machine, wherein the main body is movable in a longitudinal direction .