JPH07111763A - Carbon brush - Google Patents

Abstract

PURPOSE:To prevent the damage of a commutator which is caused by the contact of the lead wire of a brush with the commutator at wear of the brush, and to make the commutator usable sufficiently even at the insertion of a second brush. CONSTITUTION:In the place of a carbon brush 1 which is closer to a commutator than the end of a lead wire 2, an insulator 4 is provided, and the lead wire 2 is fastened to the carbon brush 1 by a copper powder 3. By this more excellent configuration than the ones of conventional carbon brushes, in case of the chafing of the carbon brush 1, the driving of a motor can be stopped without the damage of the commutator, since the insulator 4 is contacted with the commutator ahead of the lead wire 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a carbon brush for electric machinery (hereinafter referred to as a brush).

[0002]

2. Description of the Related Art Brushes are used in commutator motors and generators, but especially brushes used in household vacuum cleaners and cooker commutator motors have a short brush life and require brush replacement. is there.

A conventional brush will be described below.
FIG. 4 shows a brush with a lead wire.

FIG. 5 shows a cross section of the brush. 4 and 5, 1 is a brush and 2 is a lead wire.
The lead wire 2 is inserted into the insertion hole formed in the brush 1 and is fixed by the copper powder 3.

The brush constructed as described above wears from the side opposite to the lead side as it is operated, but at the end the lead wire is exposed and comes into contact with the commutator.

[0006]

However, in the above-mentioned conventional structure, when the brush is worn, the commutator and the brush lead wire come into contact with each other to generate a spark. If this spark continues for a long time, the surface of the commutator will be damaged, the accuracy of the commutator surface will deteriorate, and there will be a problem that the brush will be worn out immediately even if the second brush is inserted. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a brush which solves the above-mentioned conventional problems and which causes less sparking when the brush wears and the motor stops in a short time.

[0008]

In order to achieve the above object, the brush of the present invention has a structure in which an insulator is provided at the brush wear limit portion of the head of the brush body.

[0009]

With this configuration, when the brush is worn, the insulator is exposed before the lead wire, and at that time, the lead wire and the commutator are no longer connected to each other, and the operation of the electric motor can be stopped.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. In the figure, the same members as those in the conventional example are given the same numbers. 1, FIG. 2, and FIG. 3, 1 is a brush, 2 is a lead wire, 4 is an insulator, and 3 is a copper powder fixing the lead wire 2 and the insulator 4 to the brush 1.

In the above structure, the brush is worn away from the side opposite to the lead side as it is operated, but the insulator is exposed before the lead wire, at which point the lead wire and the commutator are no longer connected and the motor is stopped. . The spark is generated for a short time and the commutator surface is not damaged so that the second brush can be sufficiently operated.

As described above, according to the present embodiment, by providing the insulator at the wear limit portion of the brush, the spark generation time at the time of brush wear can be shortened, and the operation of the electric motor can be performed without damaging the commutator. Can be stopped.
Operation with the second brush is also possible.

The insulator 4 is preferably made of a ceramic material which is harder than the brush 1 and resistant to heat, and has a spherical shape.
It goes without saying that the desired effect can be obtained if the shape is a half or less of the brush cross-sectional area, such as a square shape or a deformed square shape.

Further, although the lead wires are oriented in the horizontal direction in FIG. 3, it goes without saying that the same configuration as in FIG. 1 can be used.

[0015]

As is apparent from the above description, the brush of the present invention is provided with an insulator having a hardness higher than that of the brush at the wear limit portion, so that the insulator becomes a commutator before the lead wire when the brush is worn. By making contact with each other, the operation of the electric motor can be stopped without damaging the commutator, and the excellent carbon brush can be brought into a sufficiently operable state even when the second brush is inserted.

[Brief description of drawings]

FIG. 1 is a sectional view of a brush according to an embodiment of the present invention.

FIG. 2 is a sectional view of a brush according to another embodiment of the present invention.

FIG. 3 is a sectional view of a brush according to another embodiment of the present invention.

FIG. 4 is an external perspective view of a brush with lead wires.

FIG. 5 is a sectional view of a conventional brush.

[Explanation of symbols]

 1 Carbon brush 2 Lead wire 3 Copper powder for fixing 4 Insulator

Claims (3)

[Claims] 1. A carbon brush characterized in that a lead wire is provided at the head of the brush main body, and an insulator having a hardness higher than that of the carbon brush is provided at a brush wear limit portion. 2. The carbon brush according to claim 1, wherein a ceramic material is used for an insulator having a hardness higher than that of the carbon brush. 3. The carbon brush according to claim 1, wherein the insulator is a sphere or a prism and has a cross sectional area of 1/2 or less of the brush.