SU1723590A1 - Method of manufacture of electromagnetic devices - Google Patents

Abstract

This invention relates to electromagnetic devices. In the manufacture of protected electromagnetic devices, it is placed in a housing with a gap, and the gap is filled with heat-conducting electrically insulating filler. The filler is made of powder material - periclase and compound - bishafit. Then the device is dried at 100-200 ° C. This method allows to increase the reliability of the device, to increase its heat transfer, since the thermal conductivity of the filler rises to 0.6-0.7 W / m ° C.

Description

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The invention relates to electrical engineering, in particular, to methods for manufacturing electromagnetic devices.

A known method of manufacturing electromagnetic devices of a protected execution is placed in an outer case filled inside with a mixture of powdered silica filler and resin.

The disadvantage of this method is low () p 0.2-0.3 W / m ° C) the average thermal conductivity of the mixture due to air inclusions, low mixture fluidity and occupancy of the internal cavities of the device. The use of a mixture of a quartz complex with a high thermal conductivity coefficient (L 0.9 W / m ° C) requires the use of vacuum impregnation under pressure, which is not suitable for mass production of electromagnetic devices of a protected design.

There is also known a method for manufacturing electromagnetic devices of a protected design, for example, vibratory pumps Kid, in which an electric coil worn on a magnetic circuit is installed in a housing and filled in air with a hot compound based on powdered silica and epoxy resin.

The disadvantage of this method is due to the low average value of the coefficient of thermal conductivity of the mixture used. The lack of thermal conductivity of the filler and heat transfer from the outer pump housing leads to the combustion of its coil within 0.5 hours of work in a well without water.

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The purpose of the invention is to increase the thermal conductivity of the filler and the reliability of the device by increasing heat transfer.

The goal is achieved by the fact that according to the method of manufacturing devices of a protected version, in which the device is placed in a case, then it is filled with a heat-conducting filler made of a powder material and a compound, followed by drying, as a powder material - bishafit, and the drying is carried out by heat treatment of the device in the temperature range above the beginning of the evaporation of water from bischofite (more than 100 ° C) and below the maximum permissible by insulation class cat device ears (up to 200 ° C).

The increased thermal conductivity, density and mechanical strength of the preparation of the filler is achieved due to the fact that the basic salt, originally formed from periclase (MDO) and an aqueous solution of bishafit (MgCte bNZO) according to the equation MgO + MCte + Had 2MgOHCI, polymerizes in a chain of magnesium atoms oxygen locked at the ends by the remaining atoms of the compound. The mechanical strength of the resulting compound reaches a level at which it can be used in abrasive products and millstones.

Tests have shown that a chemical compound based on periclase and bishafit has a thermal conductivity of 0.6–0.7 W / m ° C, a specific electrical resistivity of 10–10 Ohm-m and a significant linear expansion allowing it to be used in as an effective heat-conducting and electrically insulating filler.

A method of manufacturing electromagnetic security devices is carried out as follows.

The device in an assembled state is placed on a horizontal surface so that its filled cavities are facing upwards, and the casing and surfaces of the electromagnetic part of the device form walls to hold periclase and bischofite. The prepared dry electrotechnical powder through a funnel with a crane or through a nozzle is fed into all filled cavities of the device until the calculated amount of powder is consumed. Shake the device if necessary; After reaching 90% of the height of the cavities, the calculated amount of bishafit is formed, forming a water surface at the upper level of the cavities of the device. 10-15 minutes after the spontaneous absorption of the bishafit and keeping only its residue on the surface, pour out the rest of the periclase and close the lid if there is a cover.

Bishafit is capable of impregnating periclase to a depth of 100 mm in about 10 to 15 minutes. At greater depths, layering and wetting should be used. In the closed case of the device several removable plugs should be provided, which are removed after the device is filled with filler. The device is placed on a conveyor and sent to an oven with a temperature above 100 ° C. The choice of temperature is determined by the productivity of the process of evaporation of water from the mixture, i.e. drying and permissibility of heating according to the class of wire and coil insulation (up to 200 ° C). After-furnace drying is possible by connecting coils of devices to an electrical source. Drying is carried out until the filler solidifies, which is determined by stopping the release of water vapor from the plug holes, which are then closed.

Replacing the air inside the cavities of the device, which has a coefficient of thermal conductivity and 0.3 W / m ° C) with a dense ceramic material that exerts great pressure on the walls due to expansion and has a coefficient of thermal conductivity of 0.6 - 0.7 W / (m ° C) , increases heat transfer to the outer surface, and consequently, the power of the device (approximately 40%).

The use of a polymerized periclase with the Baby pump, with its long-term activation without water, eliminates the burning of the coil, and the superheat is only 160 ° C.

A fo rm a lm and a b r o p t e Method of manufacturing electromagnetic devices of a protected version, in which this device is placed in a case, then the cavities between the device and the case are filled with heat-conducting electrically insulating filler made of a powder material and compound followed by drying the filler, characterized in that, in order to increase the reliability of the device by increasing heat transfer, periclase is used as the powder material. and as a compound, bishafit, and drying is carried out by heat treatment at 100-200 ° C.

Claims (1)

Claim A method of manufacturing electromagnetic devices of protected design, in which this device is placed in a housing, then the cavities between the device and the housing are filled with heat-conducting electrical insulating filler made of powder material and compound, followed by drying of the filler, characterized in that, in order to increase the reliability of the device by increasing heat transfer, periclase is used as a powder material, and bischafite is used as a compound, and drying is carried out by heat treatment at 100200 ° C.