SU1319123A1 - Composition for electric brushes - Google Patents

Description

The invention relates to electromechanics and concerns brushes of electric machines operating under difficult switching conditions, exposure to significant vibration and shock loads, the presence of oil and oil products vapors in the contact zone, for example traction electric machines,

In the proposed composition, carbon fibers, located in the open pores of a porous electrographitized material, penetrating its entire volume, are additional conductors of electric current, which contributes significantly to the stability of the physicomechanical characteristics of brushes, especially their electrical resistivity. The presence of additional paths of electric current in the brush makes it possible to significantly relieve the main electrographic brush material, to reduce the actual current density in the contact, which contributes to increasing the switching capacity of the brush-collector assembly. The presence of flexible carbon fiber in the pores increases the density, strength and elasticity of the brush, which contributes to the increase in wear resistance and service life of brushes and reduce friction losses in the sliding contact,

Hydrocarbon fibers with a diameter of 0.02–7.0 µm are introduced into the open pores of a porous electrographitized material with the following ratio of component components, wt%: carbon fibers with a diameter of 0.02–7.0 µm 0.2–12.0 porous electrographic material else.

When the values of the components of the brushes are outside the specified limits, the stability of the physicomechanical characteristics decreases and the performance properties of the brushes deteriorate.

When the content of carbon fibers in the brush is below the proposed limit, the instability of the electrical resistivity increases, the density, strength and elastic properties of the brush decrease, the wear and friction coefficient increase.

If carbon fibers are contained above the proposed limit in the brush, the brush hardness increases significantly, which leads to deterioration of the mechanical characteristics of the contact and covering the collector

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copper. The brush produces a considerable thickness polish, as a result of which the main transfer is the fritting (breakdown) of the collector film, which leads to disruptions in the process of political formation, an increase in the brush wear and friction losses in the contact.

Example 1. In the mixer with

W the working volume of the chamber 400 l load carbon black (15 wt,%), pitch. coke (30.1 wt.%). The powders are mixed for 30 minutes before, then 37.1 wt.% Water is poured into the mixer and the mixture is stirred for 30 minutes before, the mixture of coal tar pitch (12.7 wt.%) Heated to 150 ° C is poured into the mixer and mixing for 3.5–4 h up to a temperature of 130 массы of the mass of 130 ° C; then the mass is unloaded | They are chewed and rolled on rollers heated

to 140-150 ° C. After that, the mass is cooled and milled to a particle size of less than 500 μm in size (fraction content less than 63 μm 68%) in the mill. The pressing of the blocks is carried out with each column with a density of 1.50-1.52 g / cm, the firing of the blocks is carried out in a tunnel-type furnace at a maximum temperature of 1200 ° C, and the graphitization is carried out in a furnace at 2700 ° С. make samples and brushes for testing. Specific

35 The volume of open pores according to mercury porosimetry 0.176 cm / g, pore size in diameter 0.01-3.5 microns,

Example 2, Samples of the brush material, made according to the example

 1, is subjected to a single impregnation with an organic solution of polyacrylonitrile in an autoclave at a residual pressure of 0.94 kgf / cm “Then the samples are treated in a drying oven at

45 120-150 s. The content in the polyacrylonitrile samples is 0.58 wt.%

After this, the brush blanks and samples are heated to 2700 ° C.

50 in a special oven isothermal heating. At the indicated temperatures, the polyacryl: nitrile fibrous material placed in the pores passes into the state of graphite and begins to pass a current. The yield of graphite is 34.5 wt.%. Taking into account this ratio, the content of carbon fiber in the brush is determined (0.2 wt.%). The mercury porosimetry method determines the open porosity value and the diameter of open pores. The value of the specific volume of open pores decreases by 24% and is 0.134, however, the content of open pores with a diameter of 0.02-7.0 varies only slightly. Thus, the resulting carbon fibers have a diameter of from 0.02 to 7.0 microns.

EXAMPLE 3 According to the technology of Examples 1 and 2, brush samples were prepared using double impregnation and drying. The carbon fiber content is 6.2 wt.%, The specific volume of open pores with a diameter of 0.02-7.0 μm is 0.098 CMVr.

Example 4. According to the technology of examples 1 and 2, samples of brushes were prepared using triple impregnation and drying. The carbon fiber content is 12.0 wt.%, The specific volume of open pores with a diameter of 0.02-7.0 μm is 0.061 cmu / g.

Example 5. According to the technology of examples 1. And 2, samples of brushes are prepared using four-fold impregnation and drying. The carbon fiber content of 12.82 wt.%, The specific volume of open pores with a diameter of 0.02-7.0 microns 0.036.

Example 6. According to the technology of examples 1 and 2, samples of brushes were prepared using a single impregnation in an autoclave at a pressure reduced to 0.92 kgf / cm. The content of carbon fiber with a diameter of 0.02–7.0 μm in a brush is 0.18 wt.%, The specific volume of open pores with a diameter of 0.02–7.0 μm is 1.12 cm / g.

The results of testing known and proposed brushes are shown in the table.

Claims (1)

As follows from the test results presented in table 3, the stability of the physicomechanical characteristics of brushes — electrical resistivity and hardness — is significantly increased (for example, the spread of O values of electrical resistivity is 2–10 units for the proposed brush instead of 24 units for known, 4 units instead of 6 units) the wear of the brush decreases when tested on the 5th KZK-95 unit, and when tested under operating conditions, the service life of the brushes increases by 1.2-1.5 times, due to the improved switching capacity another the current improves the condition of the 0 / brush-collector unit in operation. Invention Formula Composition for electric brushes, containing porous electrophotographic material and carbon: fibers, characterized in that, in order to increase service life, switching properties and reduce friction losses, carbon 0 fibers have a diameter of 0.02-7, 00 μm and located in the open pores of the porous electrographitized material in the following ratio of components, wt.%: 2 Carbon fibers diameter 0.02 7.0 micron 0.2-12.0 Porous Electro graphitized materialEverything give 0.18 0.20 6.23 12.0 12.82 23-58 26-32 24-30 24-28 24-26 10-160.25 12-180.20 12-160,15 14-160,12 15-160,10 The width of the spark work zone of a traction engine at j 13A / cm, % No zone, sparkling 1 1/4 No zone, arcing 1 1/4 0.98 1.42 3.74 5.24 vniipi Order 2519/48 Circulation 625 Random polygons pr-tie, about Uzhgorod, st. Project, 4 0.22 0.20 0.18 0.16 0.19 Table continuation Performance Testing Brush collector state 136 Traces of sincere and burning That is not satisfactory Also Covering collector Subscription