JPS6223258Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to the brushes of rotating electric machines, and can be easily detected by using an external alarm device such as a bell or lamp, without having to look into the narrow dark space inside the machine to check the wear level of the brushes. This has been improved so that the degree of wear of the brush can be detected.

Conventionally, in order to detect the wear of the brushes of a rotating electrical machine, as shown in FIG. The amount of reduction is visually checked. However, the area around the brushes of rotating electric machines is generally a dark area and is often narrow. Therefore, it is difficult to carry out the above-mentioned inspection work, and
Depending on the degree of darkness, there is a problem that the scale 2, brush 3, etc. cannot be clearly seen.

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, it is an object of the present invention to provide a brush for a rotating electrical machine that can easily detect wear limits, overloads, and abnormal commutation.

The present invention achieves the above object by embedding a high friction coefficient member made of carbon or the like containing a material with a high friction coefficient such as phenolic resin as a binder together with a thermocouple to the depth of the wear limit of the brush body. The technical idea is based on the fact that the above-mentioned conditions and phenomena can be detected by using a thermocouple to detect an abnormal rise in temperature.

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

As shown in FIG. 2, the brush 7 according to this embodiment
has a brush body 7a which is a normal electrographite carbon brush, a high friction coefficient member 7b having a larger friction coefficient than the brush body 7a, and a temperature sensor such as a thermocouple 8. While being accommodated, it is in contact with a commutator 6 fitted to the boss 5a of the rotating shaft 5. At this time, the high friction coefficient member 7b is buried in the brush body 7a to the depth of the wear limit of the brush body 7a. Further, the thermocouple 8 is embedded in the high friction coefficient member 7b.

Generally, carbon has a higher coefficient of friction as it has a larger amount of non-graphitizable material (ash content). Therefore, the high friction coefficient member 7b in this example was formed by selecting phenolic resin as the non-graphitizable material and making carbon contain about 10% of phenolic resin. More specifically, the high friction coefficient member 7b is formed by adding 10% phenolic resin as a binder to electrographite, which is commonly used as a brush, and firing the mixture at 2000°C to 3000°C. In this way, the friction coefficient becomes
It becomes 0.7-0.8. Incidentally, the friction coefficient of the brush body 7a, which is an electrographite carbon brush, is 0.2 to 0.3. An electrographite brush with a thickness of 12.5 mm, a width of 20 mm, and a height of 27 mm, and a brush with the same dimensions as the above brush made by adding 10% phenol resin to electrographite and using the method described above were each placed in a DC machine. implement,
When a temperature test was conducted by passing a current of 4A/cm ² through both brushes, the latter became 25°C hotter.

Therefore, when the brush 7 is reduced to the dimension d in the figure, the commutator 6 comes into contact with the high friction coefficient member 7b, and high heat is generated at this portion. This heat is detected by a thermocouple 8. Therefore, although not shown, the voltage detected by the thermocouple 8 can be amplified and used to generate some kind of alarm, such as lighting a lamp or ringing a bell.

Note that although the rotating electric machine in the above embodiment is a DC machine, it may of course be other induction machines, synchronous machines, etc. In addition, since the brush according to the present invention has a thermocouple 8 inside, heat generated in the brush body 7a due to overload and abnormal rectification and conducted via the high friction coefficient member 7b is transferred to the thermocouple. 8, these abnormal phenomena can also be detected.

In addition, in the above embodiment, the high friction coefficient member 7
b is made of a material whose main component is carbon, but the material is not particularly limited as long as the coefficient of friction is greater than that of the brush body 7a so that the brush can slide, for example, as long as it does not damage the commutator surface.

As specifically explained above with the examples,
According to the present invention, since the degree of wear of the brush can be detected using a thermocouple, there is no need to rely on visual inspection as in the past, and the condition of the brush can be easily and reliably grasped.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a brush of a conventional rotating electric machine held in a brush holder, and FIG. 2 is a partially cutaway front view showing an embodiment of the present invention together with its surrounding parts. In the drawing, 7 is a brush, 7a is a brush body, 7b
is a high friction coefficient member, and 8 is a thermocouple.

Claims (1)

[Scope of utility model registration request] The brush body is made of a carbon brush such as electrographite, and the brush body is made of a material that has a larger coefficient of friction than the brush body. Phenol resin, etc. is embedded in the brush body as a binder to the depth of the brush body's wear limit. A brush for a rotating electric machine, comprising a high friction coefficient member made of carbon or the like, and a thermocouple embedded in the high friction coefficient member.