RU1789806C - Shaft seal assembly - Google Patents

Abstract

Usage: means of sealing the shaft. SUMMARY OF THE INVENTION: a device includes a gap seal and a face seal placed in series between a housing and a shaft. Non-rotating sealing elements are made as a single part from a material with high thermal conductivity. The friction zone of the mechanical seal is located directly above the gap seal. 1 ill.

Description

The invention relates to mechanical engineering, in particular to means for sealing rotating shafts.

A shaft seal is known (application FRG, class F 16 J 15/34, No. 2844945, property 16.16. 10.78, publ. 30.04.80), comprising a mechanical seal assembly and a non-contact seal located in series with a cylindrical shaft section and a profiled sleeve mated to a fixed housing. A drawback of this device is the inability to increase the effectiveness of the labyrinth seal when fluid flows through the mechanical seal.

A device for sealing a shaft is also known, including a gap seal and a mechanical seal placed in series between the housing and the shaft, containing rotating and non-rotating sealing elements (see the book: Seals and sealing technique. Handbook, M .: Mechanical Engineering, 1986, p.329 , fig. 9.34). A feature of the seal is the presence of an annular groove in the fixed element of the gap seal,

in which fluid is supplied through the radial channel of the housing to cool the gap. Sealing has a limited scope, due to the need to control the temperature of the structure within specified limits.

The aim of the invention is to increase the reliability of the assembly when the gap seal is located on the outside of the assembly by converting the leakage of the working fluid passing through it by heating into a two-phase liquid-vapor mixture.

The goal is achieved in that in the known node of the shaft seal, including sequentially located between the housing and the shaft gap and mechanical seals containing rotating and non-rotating sealing elements, non-rotating sealing elements are made as a single part of a material with high thermal conductivity, and the friction zone of the mechanical seal located directly above the gap seal.

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WITH

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About Os

The novelty of the proposed solution lies in the fact that non-rotating sealing elements are made as a single part from a material with high thermal conductivity, and the friction zone of the mechanical seal is located directly above the slotted seal. ..

The drawing shows the proposed shaft seal assembly / Arbdbl section.

In the housing 1, a rotating shaft 2 is mounted with which the rotating mechanical seal element 3 is fastened, for example, is hermetically mounted in a sleeve 4 mounted on the shaft 1 and sealed with a rubber ring 5. The non-rotating mechanical seal element 6 is hermetically installed in the housing sleeve 7, made from a material having high thermal conductivity, for example, from a copper alloy. The elastic sealing ring 8 has three functions: it seals the housing sleeve 7 with respect to the flange 9, which is sealed in the housing; provides the necessary contact pressure between the elements 3 and 6 of the mechanical seal, which is achieved, for example, by installing an adjusting pad 10 on the shaft; and also performs the function of a hinge providing contact between elements 3 and 6 in the presence of a beating of the shaft 1. The housing sleeve 7 with the shaft 2 (in the design with the sleeve 4 mounted on the shaft) forms a gap seal 11.

In order to increase the wear resistance of the gap seal 11, which is arranged sequentially behind the mechanical seal, a sleeve 12 of antifriction material can be pressed into the housing sleeve 7, and a sleeve 13 of antifriction material can also be pressed onto the sleeve 4. Instead of sleeve 12 and sleeve 13, known anti-friction coatings (e.g. silver plating) can be used.

In the proposed construction, an annular drainage chamber 14 is additionally made in the flange 9 and communicates with the atmosphere through the channel 15 and is limited on the shaft side by a seal 16, for example, of a screw type or sleeve.

The shaft seal assembly operates as follows.

In case of leakage through the end face

the seal activates the gap seal 11. In this case, part of the heat generated from the friction of the mechanical seal elements 3 and 6 is transferred to the working fluid — leakage, and also propagates through the housing sleeve 7 to the gap seal 11 to its non-rotating sleeve 12. When high sliding speed and contact pressure (for example, at pV 10 MPa m / s,

where p is the nominal contact pressure, MPa;

V is the sliding velocity, m / s), a significant amount of heat is released, and flowing through the mechanical seal

and the gap seal 11, the liquid partially passes into steam, so that a liquid-vapor mixture flows through the seal 11. From the literature it is known (see, for example, Beatty P.A., Hughes W.F. - Turbulent twophase flow

in annular Seals. - ASLE - Traus, 1987, 30, No. 1, 11-18) that the presence of a vapor phase in the gap is an important mechanism for reducing leakage in a gap seal, and leakage of a single-phase fluid

more than two-phase, and cooling the system leads to increased leaks. A leak in the form of a liquid-vapor mixture can be discharged through the drainage cavity T4 and channel 15. A forced gas purge of the cavity 15 sealed by the external seal 16 can also be arranged. Thus, the proposed technical solution allows to obtain a positive effect, consisting in

increase the reliability of the node.

Claims (1)

SUMMARY OF THE INVENTION A shaft seal assembly comprising slotted and mechanical seals arranged in series between a housing and a shaft, comprising rotating and non-rotating sealing elements, characterized in that the non-rotating sealing elements are made as a single piece of material with high thermal conductivity, and the friction zone of the mechanical seal is located directly above the gap seal, which is located on the outside of the assembly.