JPH0128378Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to shaft seal technology, and relates to an improvement of a mechanical seal as a dry seal that seals a gas in a dry state.

[Conventional technology]

BACKGROUND ART In recent years, for example, in the field of pharmaceuticals and fine chemicals, various types of mechanical seals, so-called dry seals, have been used as means for sealing the pressure gas sealed in the stirrer of a reactor.

FIG. 4 shows an example of the above mechanical seal,
In the figure, symbol a is a non-rotating alumina or silicon carbide floating sheet closely fixed to the inner periphery of the housing c on the fuselage side, b is airtightly supported on the outer periphery of the rotating shaft d via a bellows e, and the bellows A rotating ring made of fluorinated ethylene resin that is pressed in the axial direction by coil springs e and coil springs f.The rotating ring b and the floating sheet a slide closely against each other with appropriate surface pressure, allowing the floating sheet to move into the machine. It seals the various gases G enclosed. Originally, this mechanical seal was often used primarily for the purpose of sealing liquids, but due to the materials of the floating seat a and rotating ring b, it has good sliding characteristics, so it is used as a dry seal as described above. It is also ideal for applications such as

[Problem that the invention attempts to solve]

However, the sealing performance of the mechanical seal against gas G is limited between the floating seat a and the rotating ring b.
To explain in more detail, when the temperature of the sliding part is relatively high, the micro roughness of the sliding surface becomes smooth due to heat, so the amount of leakage increases. However, under low-temperature conditions, particularly at temperatures below 0°C, moisture contained in the machine and in the atmosphere will freeze in and around the sliding parts, causing damage between the sliding surfaces of floating sheet a and rotating ring b. The problem is that the gap between seals becomes larger, or the sliding surface becomes worn and roughened due to ice crystals, etc., which increases the amount of leakage and shortens the life of the seal.

[Means for solving problems]

The present invention was developed with the aim of solving the above-mentioned problems, and is characterized by having a heating mechanism such as an electric heater on the floating seat on the non-rotating side of a mechanical seal used as a dry seal. .

[Effect]

That is, by heating the floating sheet using the heating mechanism and maintaining it at an appropriate temperature range above a certain level, the freezing of moisture in the sliding part of the floating sheet with the rotating ring and its vicinity is prevented. It is possible to prevent the progress of wear and surface roughness on the sliding surface.

〔Example〕

Hereinafter, embodiments of the present invention will be described based on the drawings.

First, in the first embodiment shown in FIGS. 1 and 2, conductive means 4, 4 are provided on the stepped end surface 3 formed on the outer periphery of the sliding surface 2 of a floating sheet 1 of a mechanical seal used as a dry seal. A substantially C-shaped plate-shaped electric heater 5 is connected to an external power source (not shown) through the floating sheet 1.
Since the sliding portion of the rotary ring 6 is heated to an appropriate temperature level by the heater 5, it is possible to prevent the sliding portion and its vicinity from freezing. FIG. 3 shows another embodiment in which a floating sheet 1' made of alumina or silicon carbide is directly connected between the terminals 7, 7 of the conductive means 4, 4 connected to an external power source, so as to conduct electricity. The floating sheet 1' itself is used as a heating element based on electrical resistance.

[Effect of idea]

As explained above, the mechanical seal of the present invention has a heat generating mechanism in the floating sheet, so when used as a dry seal under low temperature conditions, the sliding surface may wear out prematurely due to freezing of the sliding part and its vicinity. It also exhibits excellent effects such as suppressing surface roughness and significantly improving sealing performance and seal life.

[Brief explanation of the drawing]

Fig. 1 is a half-cut sectional view of essential parts showing one embodiment of the present invention, Fig. 2 is a perspective view of a floating sheet, Fig. 3 is a perspective view of a floating sheet in another embodiment, and Fig. 4 is a perspective view of a floating sheet in another embodiment. It is a half-cut sectional view showing a conventional structure. 1, 1'...Floating sheet, 2...Sliding surface, 4...Conducting means, 5...Electric heater, 6...
...Rotating ring, 7...Terminal.

Claims (1)

[Scope of utility model registration request] A mechanical seal used as a dry seal that seals gas through dry sliding between a rotating ring and a floating sheet, characterized in that the floating sheet on the non-rotating side has a heat generating mechanism such as an electric heater. Mechanical seal.