JPS581978Y2 - ceramic hermetic terminal - Google Patents

Description

[Detailed description of the invention] This invention is a ceramic airtight terminal used for power introduction terminals of electrical equipment (including electric heaters) placed in tanks and pressure vessels filled with fluids such as high-temperature water and steam. It is related to.

Conventionally, the above-mentioned ceramic airtight terminals have been widely used because they have excellent electrical insulation properties under fluid conditions such as water and steam.

A conventional terminal of this kind is constructed as shown in Fig. 1 (a ceramic e is attached via a flange d to the tip of an exterior sheath C which has a lead wire inside through an insulator a, and the ceramic e and the lead wire are connected to each other through a flange d). The exterior sheath C is attached to the wall g of a tank or pressure vessel, etc. by welding, etc., and is placed inside the tank or pressure vessel. The ceramic e in the power introduction terminal i was exposed, but this ceramic airtight terminal can withstand temperatures from room temperature without any problem if it is constantly in fluids such as water or steam. High-temperature water, steam, or other fluids filled in tanks, pressure vessels, etc. that exhibit excellent electrical insulation properties up to 4,000 ℃ are supplied from the equipment process, are suddenly released, or conversely are cooled. Since fluid may be injected into a tank or pressure vessel, in such a case, the power introduction terminal portion i, that is, the ceramic material e, of the conventional product is subject to rapid temperature changes.

Although the above-mentioned ceramics have excellent electrical insulation properties, they are made of inorganic fired materials such as alumina, magnesia, and cordierite, so they are resistant to thermal shocks up to 150% due to temperature changes.
Ceramic e can withstand only about C, and if it is subjected to temperature changes exceeding this temperature, the ceramic e itself cracks, allowing fluids such as water and steam to enter through these cracks, resulting in a loss of electrical insulation properties.

Therefore, the present invention was developed in view of the above-mentioned drawbacks of the conventional technology.
In the power introduction terminal part of the ceramic hermetic terminal, by providing an appropriate thermal buffer part through an air gap in the ceramic part, it is possible to maintain sufficient electrical insulation function even against temperature changes up to about 300'C. The purpose is to

The drawings showing the embodiments of the present invention will be described in detail below.
In FIG. 2, the power introduction terminal part 2 of the electrical equipment 1 placed in a tank or pressure vessel (not shown) is connected to a flange made of Kovar or the like at the tip of an exterior sheath 5 which has a lead wire 4 inside through an insulator 3. 6 is attached by welding or the like, a ceramic l is airtightly attached to the tip of the flange 6 using, for example, a silver plate, and the ceramic γ and the lead wire 4 are airtightly connected with a sleeve 8 made of Kovar or the like. ing.

Further, the ceramic 1 and the sleeve 8 are hermetically bonded by silver solder or the like, and the sleeve 8 and the lead wire 4 are hermetically bonded by welding or the like.

In the present invention, the outer periphery of the ceramic γ is covered with a heat-resistant coating 9 made of an insulating inorganic or organic material so that the ceramic γ is not exposed to the outside. In this method, a tube 9a made of the above-mentioned material is fitted onto the outer periphery of the ceramic γ over the flange 6 and the sleeve 8 as shown in FIG. An air gap 10 is formed between the tube 9a and the outer periphery of the tube 9a.As for the material of the heat-resistant coating 9, alumina, Teflon, cordierite, Macol, etc. can be used for the tube 9a.

As explained above, according to the ceramic airtight terminal according to the present invention, the ceramic γ of the power introduction terminal portion 2 is covered with the heat-resistant coating 9 made of an insulating inorganic or organic material, so that the ceramic γ is not exposed. In addition, since an air gap 10 is formed between the coating 9 and the ceramic γ, even if the power introduction terminal 2 undergoes a sudden temperature change, the heat will not propagate directly to the ceramic γ. Instead, the heat is propagated by conduction through the heat-resistant coating 9 on the outer periphery and the air gap 10, and both 9° and 10 have a buffering effect against thermal shock caused by sudden temperature changes in the surrounding area. Since it protects the ceramic γ, cracks do not occur in the ceramic γ, and there are young fruits that can maintain excellent electrical insulation properties for a long period of time even against large temperature changes.

[Brief explanation of the drawing]

FIG. 1 is a vertical side view showing a conventional ceramic airtight terminal, and FIG. 2 is a vertical side view showing a ceramic airtight terminal according to the present invention. 2... Power introduction terminal part, 3... Insulator, 4... Lead wire, 5... Exterior sheath, 6... Flange, γ・
...Ceramics, 8...Sleeve, 9...Heat-resistant coating.

Claims (1)

[Scope of utility model registration request] A ceramic is attached via a flange to the tip of an exterior sheath that has a lead wire inside through an insulator, and the ceramic is connected from the flange to the power introduction terminal section, which is formed by airtightly connecting the ceramic and the lead wire with a sleeve. A ceramic hermetic terminal comprising a sleeve covered with a heat-resistant coating made of an insulating inorganic or organic material to form an air gap between the coating and the ceramic.