SU997153A1 - Composite material for electric machine commutators - Google Patents

Description

.G

  The invention relates to electrical materials, in particular to composite materials based on carbon fiber materials used for collectors of electrical machines.

The closest to the invention is a composite material for collectors of electric machines based on carbon fiber materials and insulation, bonded with a polymeric binder. In the Analogs presented, the alternation of a layer of carbon fabric with an insulating one increases the electrical resistance of the material only in the direction perpendicular to the plane of the said layers, which slightly increases its switching capacity. To further improve the switching properties, it is necessary that in the direction of one of the axes of the rectangular coordinate system the material has a low electrical resistance, and

in the other two directions did not conduct. - electricity. In this case, the contact resistance of the current collection elements. Made of such material, it is inversely proportional to the contact area, which significantly improves the process of switching in an electric machine.

The purpose of the invention is to improve the switching properties of the material.

The goal is achieved by the fact that

10 material contains parallel laid carbon fibers, each of which is covered with an insulating composition in the following ratio of components, wt.%:

Carbon Fiber70-80

15

Isolating composition 20-30

The coating of each fiber with an insulating composition provides a pronounced amisotropy of electrical properties, i.e. high electrical conductivity of the material in one direction (along the fibers) and relatively low electrical conductivity in the two other directions of the Cartesian coordinate system (across the fibers), determined by the resistance of the insulation between adjacent fibers. The positive effect of high FDI electrical properties of this composite material is that the contact resistance of the brush with the lamella varies inversely proportional to the area of contact. In this case, the resistance difference below the running and incident edges of the brush at the end of the switching period increases (ideally, to an infinitely large value). And this means that at the moment of opening (locking) of the sections by the bark of the winding, the breaking current has an insignificant value, thereby reducing the amount of air released in the sliding contact at the final switching stage. Thus, spark-free operation of the brush contact in the electric machine is achieved, thereby reducing the electroerosive wear of the contacting elements and the level of radio interference. To obtain a composite material, carbon fibers of the PAN type are coated with a heat-resistant insulating compound - lacquer of the type PE-943. To apply an insulating coating, the carbon fibers are dipped into a bath with the liquid phase of the specified insulating composition and dried at a temperature of leO-lSO C. Then the carbon fibers with the applied insulation are impregnated with polymeric binder T-1, subjected to secondary drying at each other and placed parallel to each other in a press -form and pressed at 180-200 C and a pressure of 150-200 at.:. If you need to increase the thickness of the insulation coating, the process of applying the insulation was repeated several times. Example 1. PAN - fibers are coated with a heat-resistant insulating compound - a lacquer of the type PE-943, dipped in an insulating bath, followed by drying in a scapula at. The result is a carbon fiber coated with an insulating composition, in the following ratio of components, wt.%: PAN - fiber 70; lacquer of type PE-943 30. Then the insulated carbon fibers are impregnated with silicone binder T-1, dried at 60 ° C, placed in a mold, and pressing is performed at a pressure of 200 at and 180 ° C before polymerization of the binder. Example 2. Operations are carried out as in example 1, with carbon fibers coated with an insulating composition at the following ratio of components, wt.%: PAN - fibers75 Lacquer type PE-94325 Example 3. Operations are performed as in example 1, with carbon fibers coated with an insulating composition The following ratio of components, wt.%: PAN - fibers80 Lacquer type PE-94320 The main physicomechanical properties of the proposed composite material and the prototype are tabulated. As can be seen from the table, the composite material of example 2, made on the basis of PAN fiber and heat-resistant insulating composition - varnish type PE-943 in a weight ratio of 75-25, respectively, has better properties compared to other materials listed in the table.

Claims (1)

Therefore, the indicated weight ratio of material components is optimal. Deviations in the weight ratios of the components of the proposed composite material adversely affect its properties. For example, an increase in the content of an insulating composition in a composite material of more than 25% leads to an increase in its electrical resistivity, and consequently, an electric loss in the brush-collector contact increases. In this case, overheating of the current collection elements is possible, which causes wear and tear on contact with the elements and facilitates spark formation. Reducing the content of the insulating composition to less than 25% significantly reduces the reliability of the insulation coating of carbon fibers, thereby providing the necessary anisotropy and the switching properties of this composite material are reduced. Thus, a composite material based on carbon fibers with preliminarily applied insulation in a weight ratio of 75:25, respectively, has the best mechanical characteristics and commuting properties. The electrical resistivity of this composite material is relatively small, so it can be used for the manufacture of collectors of electric machines. Its low density and high strength properties make it possible to manufacture collectors that can be used at peripheral speeds above 100 m / s. 9 36 The high switching capacity of the proposed material is due to the fact that its contact resistance in the process of switching varies inversely with the area of contact. This, in turn, provides spark-free operation of the brush contact, reduction of contact parts, reduction of radio interference, and increased service life of the electric machine. The use of this composite material in the production of collectors significantly improves the quality and service life of collector electric machines. Claims of Invention Composite material for collectors of electrical machines based on carbon fiber materials and insulation, brace. polymeric binder, characterized in that, in order to improve the switching properties of the material, it is made in the form of parallel laid carbon fibers, each of which is covered with an insulating composition in the following ratio of components, wt.%: Carbon fiber 70-80 Insulating composition .20- 30 Sources of information taken into account in the examination}. USSR author's certificate N 670993, cl. H 01 R 39/04, 1979.