UA71935C2 - Shaft seal - Google Patents

Abstract

A shaft seal is intended for use in turbo-compressors and pumps. To decrease the friction coefficient between the rotary gasket ring and axial-movabletightening ring made of solid alloy there is installed an intermediate ring made of carbon-graphite. At that, due to gas forces acting in the tightening gap the intermediate ring is tight pressed to the axial-movable tightening ring, and for tightening the contact surfaces of the ends of both rings are to be grounded. The axial-movable tightening ring provides small deformations at high pressure, and the intermediate ring p[provides high tribotechnical properties of the friction couple.

Description

Description of the invention

The invention relates to sealing technology and can be used in turbocompressors and pumps of various purposes for sealing rotating shafts.

The closest to the one that is claimed, in terms of technical essence and the positive technical and economic effect that is achieved, is the design of the shaft seal, which is accepted as a prototype and contains an axially movable sealing ring installed hermetically in the housing and separating the high and low pressure cavities. with a pressure spring and a secondary seal placed in the annular groove of the housing, and a rotating sealing ring fixed on the shaft 70 (Patent of Ukraine Mo21905 E16.)15/16 dated 28.02.95).

However, this design of the shaft seal has low reliability, because in the process of operation at high pressures, the shaft seal loses its self-centering ability. In practice, there are cases when the composition of the pumped gas may change during the operation of the compressor. In these cases, the seal does not work according to the calculated parameters, which also reduces the reliability of the sealing unit. 19 The invention is based on the task of increasing the reliability of the shaft sealing operation in different modes by improving the tribotechnical properties of the friction pair "axially movable sealing ring - rotating sealing ring", as well as by using grooves on the periphery of the rotating sealing ring with stepped sections of different depths and geometric forms

The task is solved by the fact that the shaft seal, which contains an axially movable sealing ring with a compression spring and a secondary seal located in the annular groove of the housing, which is hermetically installed in the housing and separates the high and low pressure cavities, and a rotating sealing ring fixed on the shaft, on the end surface of which a sealing partition is made and located on the periphery of the groove, according to the invention, between the rotating sealing ring, on the outer periphery of which the grooves are made, and the axially movable sealing ring, an intermediate ring made of carbon graphite is installed. The grooves are made in the form of a trapezoid. The grooves are additionally equipped with at least one recess and/or protrusion in the form of a trapezoid. The grooves are made in the form of an equilateral trapezoid. The grooves are additionally equipped with at least one recess and/or protrusion in the form of an equilateral trapezoid. The grooves are made in the shape of a rectangle. The grooves are additionally equipped with at least one recess and/or a protrusion made in the form of a rectangle

Thus, the proposed design of the shaft seal has the following distinguishing features: c - an intermediate ring is installed between the rotating sealing ring, on the outer periphery of which grooves are made, and the axially movable sealing ring. This is provided to reduce the coefficient of friction between the axially movable sealing ring and the rotating sealing ring, which allows the use of axially movable sealing rings and rotating sealing rings manufactured

Made of hard alloy materials, which, in turn, allows to reduce the amount of deformation of these rings and preserve - the self-centering ability of the shaft seal; - the groove is made in the form of an equilateral trapezoid. Designed for gas capture. The design of the groove allows capturing the same amount of gas during normal and reverse rotation of the shaft. This is ensured by the equality of the angles of inclination of the sides of the trapezoid; With 70, the groove, made in the form of an equilateral trapezoid, works equally in both directions of shaft rotation, which is also convenient when replacing parts (the rings for the right and left seals are identical). Another advantage

The purpose of using this groove is to prevent the rings from breaking in the event of a possible emergency rotation of the shaft in the opposite direction from the usual direction; - the groove is additionally equipped with at least one recess and/or protrusion made in the form of an equilateral trapezoid. The stepped structure of the groove creates zones of increased pressure at each step of the groove, and that makes the bearing layer more rigid and the sealing gap more stable; the shape of the protrusion or recess in the form of an equilateral trapezoid is intended to repeat the geometry of the initial groove; - the groove is made in the form of a trapezoid. Designed for gas capture. It allows capturing different amounts of gas during normal and reverse rotation of the shaft, which is provided by the difference in the angles of inclination of the side sides of the 20 trapezoid; a groove made in the form of an arbitrary trapezoid does not work equally in both directions. The angle of inclination of the sides of the trapezoid can be used to adjust the efficiency of gas injection and, accordingly, the gas consumption. - the groove is additionally equipped with a depression and/or a protrusion made in the form of a trapezoid. The stepped structure of the groove creates zones of increased pressure on each step of the groove, which makes the bearing layer more rigid, and the sealing gap more stable; the shape of the protrusion or recess is made in the form

GF) trapezoid in order to repeat the geometry of the initial groove; - the groove is made in the shape of a rectangle. A rectangular groove does not work as efficiently as a trapezoidal groove, but it is easy to manufacture, which is its main advantage (due to the right angles); the rectangular groove works equally in both directions of shaft rotation; 60 - the groove is additionally equipped with a recess and/or a protrusion made in the form of a rectangle. The stepped structure of the groove creates zones of increased pressure on each step of the groove, which makes the bearing layer more rigid and the sealing gap more stable; the shape of the protrusion or depression is made in the form of a trapezoid in order to repeat the geometry of the original groove; - the intermediate ring is made of carbon graphite. Carbon graphite impregnated with various components (antimony, silicon, phenol-formaldehyde resins, etc.) has good tribotechnical (antifriction) properties, which is necessary when placing an intermediate ring between an axially movable sealing ring and a rotating sealing ring, which are made of hard alloy materials (silicon carbide, tungsten carbide, etc.). This provides good tribotechnical properties of the pair "hard alloy on hard alloy".

The stepped structure of the groove creates zones of increased pressure on each step of the groove, which makes the bearing layer more rigid and the sealing gap more stable; the shape of the protrusion or recess is made in the form of a trapezoid in order to repeat the geometry of the original groove.

Traditionally, in the nodes of dry gas seals, the rotating sealing ring is made of a hard and durable material, as a rule, from a hard alloy (silicon carbide, tungsten carbide, etc.), and/or the axially movable sealing ring is made of a material with lower strength properties with with good tribotechnical properties, as a rule, from carbon graphite impregnated with various components (antimony, silicon, phenol-formaldehyde resins, etc.). The main condition for the satisfactory operation of the seal is the condition of preserving the plane-parallelism of the sealing gap between the rotating sealing ring and the axially movable sealing ring. With relatively small changes in the value of the gas gap /5, a pair of forces appears that tends to restore the initial gap. That is, the seal has a self-centering ability.

However, strong deformations of the carbon graphite axial-moving sealing ring occur in the sealing units operating at high pressures (over 110 kg/cm?). The size of the deformations exceeds the size of the sealing gap and, therefore, the seal loses its self-centering ability. In order to reduce the deformations of the axially movable sealing ring, it, like the rotating sealing ring, must be made of hard alloy. However, the "hard alloy on hard alloy" friction pair has weak tribotechnical properties. To reduce the coefficient of friction in this technical solution, an intermediate ring made of carbon graphite is installed between the rotating sealing ring and the axially movable sealing ring made of hard alloy. At the same time, due to the gas forces acting in the sealing gap, the intermediate ring will be tightly pressed against the axially movable sealing su

Rings, and for sealing, the contact surfaces of the ends of both rings must be ground.

The axially movable sealing ring will provide small deformations at high pressure, and the intermediate i9) ring will provide good tribotechnical properties of the friction pair. When designing a seal, one of the calculated values is the depth of the dynamic grooves. The parameter that affects the calculated depth of the groove is the viscosity of the gas being compacted. Viscosity, as is known, depends on the composition of the gas being compressed and its parameters (temperature, pressure). In practice, however, there are cases when the compressor not only operates at different modes (in terms of temperature and pressure), but the composition of the pumped gas may change during operation. In these cases, the compaction does not work according to the calculated parameters, which reduces Ge"! reliability of the sealing assembly. The proposed design of the shaft seal makes it possible to reverse the direction of rotation of the shaft, and due to the dynamic grooves with stepped sections of different depths - to obtain stable operation of the seal at different modes (by temperature and pressure) and for different composition of the gas - which is being sealed. The stepped structure of the dynamic groove creates zones of increased pressure at each step of the groove, which makes the bearing layer more rigid and the sealing gap more stable.

Thus, all essential features of this technical solution are aimed at solving the given task, namely at increasing the reliability of the shaft sealing.

The essence of this invention is explained by the drawings, where Fig. 1 shows a longitudinal section of the shaft seal; - Fig. 2 - a view of the groove in the form of an equilateral trapezoid; Fig. 3 - a view of a groove in the form of a trapezoid; Fig. 4 - a view of a groove in the shape of a rectangle. "» The shaft seal contains the following details:

On the shaft 1 are installed the body 2, the main sleeve Z, the rotating sealing ring 4, on the end surface of which a sealing partition is made (not shown) and are located on the periphery of the groove (not shown); on -I shaft 1, an axially movable sealing ring 5 is also installed, placed in the annular groove of the housing 1, with an I-shaped bracket b, a pressure spring 7. A pin 8 is installed above the axially movable sealing ring 5. Between the rotating sealing ring 4 and an intermediate ring 9, made of carbon graphite, is installed with an axially movable sealing (Se) ring 5.

Shaft sealing works as follows:

Mami The pumped gas or liquid, which is in the high-pressure cavity (not shown), enters the sl grooves (not shown) made on the periphery of the rotating sealing ring 4. When the shaft 1 rotates, the grooves act on the gas medium or liquid and raise them pressure, resulting in a sealing layer with a higher density than in a low-pressure cavity (not shown). In addition,

Compressed gas when moving to the center meets the resistance of the bottom part of the grooves (not shown) and the sealing partition (not shown). The specified power factors allow establishing and maintaining a stable value

Ф, the end sealing gap based on the equality of hydrostatic forces acting on the outer surfaces of the co-rotating sealing ring 4 and the axially movable sealing ring 5, the force from the pressure spring 7 and the hydrodynamic balancing force arising due to the action of the grooves (not shown) on a gaseous medium. In a more acceptable version, the rotating sealing ring 4 and the axially movable sealing ring 5 are made of hard alloys, for example, tungsten carbide or metal ceramics, that is, from a material with minimal deformations during operation. An intermediate ring made of carbon graphite is installed between the rotating sealing ring 4 and the axially movable sealing ring 5, which improves the tribotechnical properties of the sealing rings 65 made of hard alloy materials when the shaft 1 rotates.

Several options for manufacturing grooves are possible (not shown). Depending on the goal they achieve,

grooves can be made in the form of an equilateral trapezoid, an arbitrary trapezoid or in the form of a rectangle.

The grooves are made as stepped areas of different depths, which allows for stable sealing operation at different modes (temperature and pressure) and for different composition of the gas being compressed. In addition, the stepped structure of the dynamic groove creates zones of increased pressure at each step of the groove, which makes the bearing layer more rigid and the sealing gap more stable.

Grooving (not shown) on the periphery of the end surface of the rotating sealing ring 4 can be done in several ways, for example, by ion etching using masks applied to the end surface of the rotating sealing ring, by laser processing, or the grooves can be made mechanically. , for example, using traditional methods of metalworking, in particular milling.

Thus, this technical solution ensures the reliability of the shaft seal operation at different temperature and pressure regimes and for different composition of the gas being sealed.

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Claims (7)

The formula of the invention 1. The shaft seal, which contains an axially movable sealing ring with a pressure spring and a secondary seal located in the annular groove of the housing, which is installed hermetically in the housing and separates 2 cavities of high and low pressure from each other, and a rotating sealing ring fixed on the shaft, on the end surface of which has a sealing partition and is located on the periphery of the groove, which differs in that an intermediate ring made of 70 carbon graphite is installed between the rotating sealing ring, on the outer periphery of which grooves are made, and the axially movable sealing ring. 2. Shaft sealing according to claim 1, which differs in that the grooves are made in the form of a trapezoid. 3. Shaft sealing according to claims 1 or 2, which is characterized by the fact that the grooves are additionally equipped with at least one depression and/or protrusion made in the form of a trapezoid. 4. Shaft sealing according to claim 1, which differs in that the grooves are made in the form of an equilateral trapezoid. 5. Shaft sealing according to claims 1, 4, which is characterized by the fact that the grooves are additionally equipped with at least one recess and/or projection made in the form of an equilateral trapezoid. 6. Shaft sealing according to claim 1, which differs in that the grooves are made in the shape of a rectangle. 7. A shaft seal according to claims 1 or 6, which is characterized by the fact that the grooves are additionally equipped with at least one recess and/or protrusion made in the form of a rectangle. Official bulletin "Industrial Property". Book 1 "Inventions, useful models, topographies of integrated microcircuits", 2005, M 1, 15.01.2005. State Department of Intellectual Property of the Ministry of Education and Science of Ukraine. 6) IF) (ze) (o) "- and - - and? -i - se) (95) sl ime) 60 b5