JPS6166547A - Brush for rotary electric machine - Google Patents

Abstract

PURPOSE:To remove the black coating produced on the sliding surface of the brush of a rotary electric machine so as to prevent the output decrease thereof, by uniformly adding to the brush material an amorphous compound which includes silica of a predetermined weight percentage and of a normal grain diameter as a main compound. CONSTITUTION:To the brush material of rotary electric machine, which has as a main compound a mixture of a metal and graphite, an amorphous compound is uniformly added which includes as a main compound silica of 0.02-2wt% to the gross weight of the brush and of the normal grain diameter of 1-100mmu. By use of the brush having such a constitution, the black coating produced on the sliding surface of the brush can be removed so that the output decrease in the machine is prevented.

Description

[Detailed description of the invention] [Field of application of the invention] The present invention relates to improvements in brushes for rotating electric machines such as motors and generators, and more particularly to improvements in abrasive brushes for rotating electric machines. [Prior art]

Brushes for rotating electric machines are known, to which a small amount of abrasives such as silica and alumina are added (for example, "Brushes for Electrical Machines and Their Use" 115-1169, published by Nikkan Kogyo Shimbun, 1976). Crystalline silica made from crushed sand or crystalline alumina with a large average particle size of 1 μm or more is used. The purpose of adding the abrasive is to remove the black film that forms on the surface of the feces mini cheetah when using the brush. This black film is mainly composed of cuprous oxide from fecal mini cheetahs and graphite from brushes, and has low conductivity. This may cause a decline in the rectification performance or output of the equipment. However, these abrasives have a large average particle size of 1μ or more, are crystalline, and have sharp crystal faces, so they have the disadvantage of wearing out the feces and brushes, whereas brushes for rotating electric machines used in automobile electrical equipment etc. , consisting primarily of a mixture of metal and graphite. This kind of brush has a black film mainly composed of graphite that forms on the sliding surface of the brush.
There is a problem that the output of the rotating electrical machine decreases. Immediately after use, the brush's sliding surface exhibits a surface texture that corresponds to the mixing ratio of metal and graphite, but as use continues, the graphite in the brush forms a thin film on the sliding surface. Because it covers the surface and has low conductivity, the contact resistance between the brush and the humutator increases, reducing the output. Such a film formed on the sliding surface of the brush cannot be removed by a conventionally known abrasive that is crystalline and has an average particle size of 1 μm or more. The reason for this is not clear, but it is presumed that the abrasive in this brush is too hard and the particles are too large to transfer into the film formed on the surface of the mini cheetah, so the brush surface is not polished.

OBJECTS OF THE INVENTION The object of the present invention is to suppress the wear of the fun mutator and brush by improving the abrasive. Another object of the present invention is to remove the black film that occurs on the sliding surface of the brush, which is a secondary problem with brushes made of a mixture of metal and graphite, and to prevent a decrease in the output of rotating electrical equipment.

Arrangement 1 of the Invention The present invention provides a brush for a rotating electric machine containing 0.02 to 2% by weight.
An amorphous compound containing silica as a main component and having an average particle size of 11μ to 100++μ is uniformly added thereto. As the main component of the brush, either a mixture of metal and graphite or a mixture of graphite alone can be used.6However, considering the necessity of removing the coating on the sliding surface of the brush (5α), a mixture of metal and graphite can be used. It is particularly effective against The effect of the silica compound added is determined by the amount added to the total weight of the brush, so the total weight of the brush should be 100% by weight.
The amount of the silica compound added is shown in weight percent. [Example] The material of the brush will be explained. As the graphite, any of carbon graphite, electrical graphite, natural graphite, etc. can be used. Furthermore, when using an organic binder such as a phenol resin, an epoxy resin, or a urea resin, the binder is converted to carbon by subsequent firing, so the amount of graphite is determined by converting the carbon generated from the binder into graphite. Graphite is used alone or mixed with metal powder such as copper to increase conductivity. Preferred metal powders include copper, silver, aluminum, tin, lead, iron, nickel, manganese, and the like. The mixing amount of metal powder and graphite powder is 10 to 8
Graphite powder is preferably 90 to 20% by weight relative to 0% by weight, more preferably 70% by weight is graphite powder relative to 30 to 80% by weight of metal powder.
~20% by weight. The brush may be composed only of metal or graphite and a silica-based compound, but other components are not excluded. Other components include, for example, molybdenum disulfide, tungsten disulfide, or boron nitride in an amount of about 1 to 4% by weight. The silica-based compound to be used is preferably SiO□-only, but may be one containing silica as a main component, such as silica-alumina in which about 10 to 30 mol% of the 5ijlt atoms in Sin are replaced with A1 atoms. Compounds etc. may also be used. Silica-based compounds are limited to amorphous compounds. An amorphous material is less likely to cause wear on the funmutator or brush, and can efficiently remove the film on the brush sliding surface. The silica-based compound used in the present invention is generally 5ic14
An amorphous compound containing silica as a main component obtained by 1) hydrolysis of silica, decomposition of an organic silicon compound, decomposition of an alkali metal silicate with an acid, etc. can be suitably used. Next, the effect of a silica-based compound is determined by its average particle size, and the range in which it can be used is an average particle size of 1 mμ to Loomμ.
limited to those of A more preferable range of the average particle size is 3 to 70 mμ. Those with an average particle size of 1 mμ or less are difficult to manufacture, difficult to handle, and lack practical value. On the other hand, those with 100a+μ or more not only cannot remove the film on the brush sliding surface, but also have a small 0 particle size distribution that wears out the mini cheater and brush, but the permissible particle size range is wide. Normally this is not a problem, and although it is not meant to be particularly limiting,
It is preferable that the total amount of particles having a particle size of 100+nμ or more and 111μ or less is 20% by weight or less of the total amount of the silica-based compound. The amount of the silica compound added is limited to 0.02 to 2% by weight. If it is less than this, there will be no effect at all, and if it is more than this, the wear of the mini cheater and brush will be significant. Note that the effect of addition is determined by the amount added relative to the total weight of the brush, so the amount of silica-based compound added is shown assuming that the total weight of the brush is 100% by weight.The silica-based compound needs to be uniformly distributed in the brush. Here, "uniform" means excluding segregation on the surface of the brush or island-like segregation inside the brush. If it is non-uniform, local wear will occur and it will not be effective in removing the film. For example, the brush is manufactured as follows. To complete a brush by adding a silica compound to graphite powder or a mixture of metal powder and graphite powder, mixing uniformly, press-molding with a mold, etc., and sintering. Here, it is preferable to use a hydrophobic silica compound, such as one in which a portion of the Si--OH groups on the silica surface are substituted with 5i-CH- groups. Hydrophobic materials increase the fluidity of the brush raw material, increase the packing density into molds, etc., and stabilize the filling amount. A test example will be explained. 30 parts by weight of natural graphite powder treated with phenolic resin (meaning the total amount of carbon and natural graphite remaining when the resin is thermally decomposed), 70 parts by weight of electrolytic copper powder, and a hydrophobic dry powder of each average particle size. amorphous SiO2
The powder was added and mixed in a mixer for approximately 1 hour. The brush material was molded using a mold and sintered at approximately 600"C to obtain a brush. 1. Assemble the brush to an OKW starter motor for automobiles, rotate the engine for 2 seconds, and rest for 28 seconds. The motor was operated for 10°000 cycles, with one cycle of operation.The performance was evaluated by measuring the output reduction rate of the motor before and after the test and the amount of wear on the mini cheater and brush (Samples 1 to 6).Comparison Therefore, tests were also conducted on samples without abrasive additives (sample 11) and samples with added crystalline SiO□ powder obtained by crushing silica sand (samples 12 to 14).The results are shown in the table. Sample No. SiO25iO=Amount□ Average particle size (a+μ)-Ω1JingdanD 1 7 2.0 2 12 0.05 3 12 0.5 4 12 1.0 5 12 2.0 6 40 1.0 11X 0 12* 40mμ 3.0 13× 4μ 1.0 14) iE 40μ 1.0X; ,O00081
,32 7,,80,061,10 6,10,0? 1,15 2.4 0.0? 1,084.2
0,10 1,303.5 0.
0? 1.2510.2 0.07
1,128, S O, 181, 60 9, 80, 212, 10 10, 50, 352, 45 Comparing the brushes of the example and those of the comparative example, it was found that the output was prevented from decreasing and the fun mutator and brush It can be seen that an excellent effect on preventing wear can be obtained. In addition, similar results were obtained regarding prevention of wear of the brush and funmutator in the case of a brush whose main component is solid graphite. Examining the test example in detail, sample 6
(Example) and Sample 12 (Comparative Example), while suppressing wear of the fun mutator etc. by using an amorphous material,
It can be seen that it is possible to prevent a decrease in output. Regarding the effect of average particle size of S+Oz, from sample 1, 4.6, average particle size 1
It can be seen that the maximum effect can be obtained with a diameter of 2 mμ. Note that when 1% by weight of amorphous 5in2 with an average particle size of about 1 μm was added, results similar to Sample 12 of the comparative example were obtained. Regarding the amount of S i O2 added, samples 2, 3, and 4.5
It can be seen from the comparison that the best results are obtained with 1.0% by weight. Although not shown in the table, Si with a hand powder particle size of 40 mμ
When approximately 4% by weight of o2 was added, although it was effective in preventing a decrease in output, the result was similar to that of the comparative example of sample 12 in terms of wear and tear on the fan mutator and brushes.

【Effect of the invention】

According to the present invention, it is possible to effectively remove the film on the surface of the Hunmutator and to suppress wear of the Hunmutator and the brush. In the case of a brush whose main component is a mixture of graphite and metal, it is possible to remove the black film on the brush surface, which was previously impossible, and it is possible to prevent a decrease in the output of the motor, etc.

Claims (2)

[Claims] (1) In a brush for a rotating electrical machine whose main component is a substance that is a member of the group consisting of a mixture of metal and graphite and single graphite, the brush contains 0.02 to 2.0% of the total weight of the brush.
A brush for a rotating electric machine, characterized in that an amorphous compound containing silica as a main component and having an average particle diameter of 1 mμ to 100 mμ is uniformly added in a weight percent. (2) In the brush for a rotating electric machine according to claim 1, the main component of the brush is a mixture of metal and graphite, and the mixing ratio of the metal and graphite is 10 to 80% by weight of the metal. A brush for a rotating electrical machine characterized by containing 90 to 20% by weight of graphite.