JPH0269911A - Insulation method for vacuum electrical equipment coils - Google Patents

Abstract

PURPOSE:To easily obtain an insulated coil in which its gas discharge is small and its moisture absorption is less in the atmosphere by fusion-depositing to cover the surface of the coil wound from an electric wire insulated with an inorganic material with fluorine resin. CONSTITUTION:An insulated coil in which an inorganic material-insulated coil 2 impregnated with an inorganic impregnating agent having a low viscosity is inserted into a stator core 1 insulated from a ground and molded with an inorganic impregnating agent having a high viscosity is heat treated to form an inorganic mold 3 made of a ceramic insulation layer having a small gas discharge amount. Its surface is coated by welding with fluorine resin to form a fluorine resin coating layer 4. The core 1, the coil 2, the mold 3 and the layer 4 are contained in a stator housing 5. Thus, the insulated coil having substantially small gas discharge and small moisture absorption in the atmosphere can be easily obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of insulating electrical equipment wires used in a vacuum environment such as semiconductor manufacturing equipment or outer space.

[Conventional technology]

Equipment used in a vacuum environment is required to emit less gas. This is because if there is a large amount of gas released from equipment, problems such as adversely affecting other equipment or requiring a longer time to pump to create a vacuum will occur.Especially in electrical equipment, gas emitted from insulating materials may cause problems. An insulated wire ring that emits a large amount of gas and releases less gas is desired.

For this reason, conventionally, the following insulation methods have been developed for insulated coils of vacuum motors and the like.

The first is an insulation method based on relatively heat-resistant organic insulating materials, such as polyamide-imide wire for the electric wire, polyimide film for the insulation film, and heat-resistant alkyd varnish for the coil varnish (Sanyo Denki Co., Ltd. Vacuum stepping motor; Lecture materials sponsored by Trikepp)
(Isao Kusunoki, Jun Murakami-1 Yoshiyuki Terui, Takashi Kobayashi, Hideo Doumeki: Vacuum, 30
(1987) 619).

The second method is to shield the insulating layer with metal and isolate it from the vacuum environment. This is a method of shielding the rotated stake with a stainless steel can (Tadashi Takematsu, Part of Moriyama, Hiroyuki Yamakawa, Masaru Ogasawara: Vacuum, 3)
(1988) 388).

The third method is to form a ceramic insulating layer by impregnating or impregnating a coil of electric wire with an impregnating agent whose main components are a silicone compound and synthetic mica (Japanese Patent Application No. 62-1
No. 6907).

However, in an insulation system mainly using an organic insulating material with relatively high heat resistance, the organic material releases a large amount of gas due to its woody nature, and it is not possible to reduce the amount of gas released from the insulating layer.

In the method of shielding the insulating layer with metal and isolating it from the vacuum environment, coils using stainless steel sheathed MI type cables have the problem that the stainless steel sheath generates heat due to eddy currents, which increases the amount of gas released from the stainless steel. In addition, the method of shielding the stator along with the coils with a stainless steel can reduces the amount of gas released, but the can increases the magnetic gearing between the stake and the rotor, reducing motor efficiency and making the structure complicated. Since it is necessary to process thin-walled cans, there are problems in that productivity is low and costs are high.

As a solution to these problems, there is an insulation method that forms a ceramic insulating layer. This insulation method involves impregnating a coil around which electric wire is wound with an inorganic impregnating agent to form a ceramic insulating layer.It is easy to obtain an insulated coil with a low amount of woody gas emissions. It also does not reduce the efficiency of the motor.

[Problem to be solved by the invention]

However, the insulating layer of the insulating wire made of an inorganic material formed in this way is porous and has a property of easily adsorbing moisture in the atmosphere, so that the adsorbed moisture is released in a vacuum.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for insulating a vacuum electrical equipment coil, which releases less gas in a vacuum environment.

[Means for Solving the Problems] Therefore, the present invention provides a wire ring in which an electric wire insulated with a non-metallic material is wound, a wire ring in which an insulated electric wire is wound and impregnated with an inorganic impregnating agent, or a wire ring in which an insulated electric wire is wound and impregnated with an inorganic impregnating agent. A fluororesin is welded and coated on the surface of the wire, which is molded with a material to form a ceramic insulating layer.

(Function) A wire ring made by winding an inorganic insulated wire in this way, or an insulated wire made by winding the wire and impregnating it with an inorganic impregnating agent, or impregnating and molding it, is heated at high temperature to form a ceramic insulating layer that releases less gas. After that, the surface of the insulated wire ring is welded and coated with fluororesin while it is not absorbing moisture.In particular, after sufficient heating and degassing treatment is performed in a vacuum, the fluororesin is welded and coated while the insulated wire is kept in a vacuum. By doing this, it is possible to completely prevent the wire from absorbing moisture, and the pores of the insulated wire are also covered in a vacuum state, which further reduces the amount of gas in the insulated wire. The evacuation time when enclosing equipment containing wires in a vacuum state becomes shorter, and the degree of vacuum achieved becomes higher.

(Example〕 Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a sectional view showing a stator of an axial gap motor using the present invention. After inserting an inorganic insulating coil 2 impregnated with a low-viscosity inorganic impregnant into a stator core 1 with ground-to-ground insulation, it is molded with a high-viscosity inorganic impregnant to form an inorganic mold 3, and the surface is covered with fluororesin. It was manufactured by applying a welded coating layer 4. Note that 5 is a stator housing.

As an inorganic impregnating agent, the following was used, which was obtained by mixing a silicone compound and synthetic mica and diluting them with a residual organic solvent. Methyl silicone resin (Shin-Etsu Chemical Co., Ltd. KR251) and synthetic fluorine mica (Topy Industries Co., Ltd. PDM-7) in a weight ratio of 1=1.
After mixing with and kneading with a ball mill, diluted with xylene,
The low viscosity inorganic impregnating agent was adjusted to have a viscosity of 500 CP at 20°C, and the high viscosity inorganic impregnating agent was adjusted to 2000 CP using a C-type viscometer.

The inorganic insulated coil 2 was impregnated with a low-viscosity inorganic impregnating agent adjusted as described above, air-dried for 1 hour, and further heated at 80°C for 2 hours.
The solvent was evaporated by heating at 120° C. for 2 hours, and this was inserted into the legs of the stator core 1 and installed in the stator housing 5.

Furthermore, the gap between the outer peripheral surface of the inorganic insulated coil 2 and the stator core 1 and stator housing 5 was filled with a high viscosity inorganic impregnating agent, and heated at 80°C for 4 hours and then at 120°C for 4 hours to evaporate the solvent, and then heated to 200°C. The methyl silicone resin was cured with C and then fired at 400°C to form an inorganic mold 3. The ceramic insulating layer formed by this inorganic mold 3 is made of SiO□, which is a decomposition product of silicone resin, and trace amounts of fluorine compounds such as SiFa and KF that vaporize from the synthetic fluorine mica in the impregnation agent during firing at 400°C. A part of it is melted down and becomes ceramic aggregate. Although this aggregate has sufficient strength, it has a porous structure due to the gases produced by the decomposition of the solvent and silicone resin being released outside the system.

After the temperature of this inorganic mold 3 has cooled to 300°C, a fluororesin is attached to the surface of the part that is in contact with the outside air, and the fluororesin is welded and coated by heating to 350°C, which is higher than the melting point of the fluororesin. Layer 4 was formed.

The above-mentioned fluororesin is required to have high heat resistance and low moisture adsorption, so we focused on three points: maximum continuous operating temperature, water contact angle, and melt viscosity for ease of welding and coating. Among various organic materials, a tetrafluoroethylene-perfluoroalkyl vinyl ether co-M combination; PFA (Daikin Industries, Ltd., Neoflon AC3839) was selected.

Further, for reference, a test piece (not shown) of an inorganic mold alone and a test piece in which a fluororesin was welded to the surface of the inorganic mold alone to form a coating layer were prepared.

In order to examine the evacuation characteristics of the stator and test piece insulated in this manner, an evacuation test was conducted by incorporating the stator and test piece into a vacuum vessel 14 of a vacuum apparatus shown in FIG. 6 is a rotary pump, 8 is a diffusion pump, and 15 is a vacuum motor using the stator described above. The measurement results of exhaust characteristics are shown in FIGS. 2 and 3. Symbol A in the figure indicates the pressure characteristics of the stator and test piece using the ceramic insulated wire of the present invention, and symbol B indicates the pressure characteristics of the stator and test piece using the conventional ceramic insulated wire.

FIG. 2 shows the exhaust characteristics when vacuum evacuation was performed for IHr, followed by haking at a relatively low temperature of 100° C. for 6 hours, and further evacuation was performed.

At the initial stage, the pressure A when a stator using the ceramic insulated wire of the present invention is installed is the pressure B when a similar stator using only the conventional ceramic insulated wire is installed.
The pressure is approximately one order of magnitude lower than that of IXI 0-5t o
It takes about one-third of the conventional time to exhaust to r r. Even if the evacuation time is increased, the value is always lower than that of characteristic B of only ceramic insulated wire. This difference is due to the difference in the amount of moisture trapped in the insulated wire ring, and is thought to be because the heking temperature is relatively low, so the rate of water release from the insulated wire ring is slow, and the water continues to be released indefinitely. The ultimate pressure was lower not only before baking but also after baking, and its effect was recognized.

Figure 3 shows the results of a single test piece, showing the exhaust characteristics when evacuation was performed for 4 hours and then haking was performed at 140°C for 19 hours. The pressure A of the test piece of the present invention is lower than the pressure B of only the inorganic insulation mold 4 hours after the start of evacuation. The reason why the ultimate pressure during baking is higher than that of the stator shown in FIG. 2 is because the surface area of the insulator is larger.

In this manner, by welding and coating the surface of the ceramic insulating layer with a fluororesin to prevent moisture adsorption, the ultimate pressure after heking can be lowered in a vacuum device that performs heking at a relatively low temperature.

In this example, the impregnating agent used to form the ceramic insulating layer is silicone-based, but it is not limited to this, and is not limited to paints made from organic metal polymers (for example, Show Excel from Showa S Electric Wire, Tyranno Coat from Ube Industries), or alkali metals. It is also possible to use a silicate-based inorganic adhesive (for example, Aron Ceramics manufactured by Noriwa Gosei ■). In addition to PFA, fluororesin such as FEP (tetrafluoroethylene-hexafluoropropylene copolymer) can also be used as the fluororesin to be welded and coated on the surface of the insulated wire ring. A spray coating method, a fluidized dipping method, etc. can be used to coat an insulated wire heated above the melting point of the resin.

〔Effect of the invention〕

As explained above, by using the insulation method of the present invention, it is possible to easily obtain an insulated wire ring that essentially releases less gas and has less water adsorption in the atmosphere. This has the effect of shortening the evacuation time when installing and enclosing equipment in a vacuum device, and making it possible to easily obtain pressures in the ultra-high vacuum region.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the stator of an axial gap motor using the ceramic insulated wire ring of the present invention, and FIGS. 2 and 3 show the insulation according to the present invention and the conventional insulation when evacuated in a vacuum device. A characteristic diagram showing the exhaust characteristics, FIG. 4 is a schematic diagram of the vacuum apparatus. ] is a stator core, 2 is an inorganic insulated coil, 3 is an inorganic mold, and 4 is a fluororesin welded coating layer. Figure 1 Figure 2 Exhaust 1 hour (H'') Figure 3 Exhaust time (Hr)

Claims (4)

[Claims] 1. A method for insulating wire wheels for vacuum electrical equipment, which comprises welding and coating a fluororesin on the surface of a wire ring made by winding electric wires insulated with an inorganic material. 2. A wire ring for vacuum electrical equipment, characterized in that a wire ring made by winding an insulated electric wire is impregnated with an inorganic impregnating agent to form a ceramic insulation layer, and then a fluororesin is deposited and coated on the surface of the ceramic insulation layer. Insulation method. 3. A method of insulating a wire for vacuum electrical equipment, which comprises molding the wire with an inorganic material to form a ceramic insulating layer, and then welding and coating the surface of the ceramic insulating layer with a fluororesin. 4. 4. The method of insulating a vacuum electrical equipment wire according to claim 1, wherein the fluororesin welding coating is performed in a vacuum.