RU2657026C2 - Sealing device of rod seal - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: sealing element of the rod seal contains at least one chamber (1), in which first and second split rings (2, 3) are placed, the parts of which are tightened by springs (6), first and second solid support rings (4, 5) that are installed on both sides from split rings (2, 3) and are made of a material stronger than the material of split rings (2, 3). Increasing the seal tightness, increasing the compressor capacity and reducing the wear of the rod seal packing rings are achieved due to the fact that: split rings (2, 3) and solid support rings (4, 5) have the same outer diameters; split rings (2, 3) are made sealing, herewith cuts of packing rings (2, 3) are overlapped and shifted relative to each other in the angular direction; on each support ring (4, 5), on the side facing split ring (2, 3) there is concentric protrusion (7), the outer surface of which is completely enclosed by depression (8) of split ring (2, 3).

EFFECT: technical solution is applied in rod seals of piston compressors of medium and high pressure operating at large pressure drops with lubrication, with limited lubrication and without lubrication of cylinders and rods.

4 cl, 5 dwg

Description

Technical field

The claimed technical solution relates to sealing technology and is used in the seals of the piston compressors of medium and high pressure, operating at large pressure drops with lubricant, with limited lubrication and without lubrication of the cylinders and seals.

State of the art

It is known, for example, the compressor high-pressure sealing device (patent of the Russian Federation for utility model No. 143449, IPC F16J 15/00 / Voroshilov I.V., No. 2013138325/06, declared 19.08.2013; publ. 20.07.2014, bull. No. 20, [1]). As in this technical solution, the specified analogue [1] contains the first stuffing box. In each first stuffing box there are O-rings of the first and second types, bracelet springs and a support ring. The rings have three radial cuts and are pulled together by bracelet springs. The support ring is made without cuts.

At the analogue [1], the sealing rings are fixed with each other by a pin.

The first disadvantage of the analogue [1] is that the support ring abuts only one of the o-rings. When changing the direction of gas movement, the second o-ring is not protected. The second disadvantage of the analogue [1] is that the support ring lies freely on the rod, which leads to wear of the support ring and rod.

Known oil seal for gas compressors (RF patent for the invention No. 2561960, IPC F16J 15/00, F04D 29/08 / Voroshilov I.V., No. 2013138323/06, declared 08/19/2013; publ. 09/10/2015, bull. No. 25 [2]). As in this technical solution, the specified analogue [2] contains sealing chambers. Each chamber contains a cut sealing ring, the segments of which are pulled together by a spring ring, and a cut end ring, whose segments are also pulled by a spring ring. Each seal chamber additionally includes a thrust ring.

At the analogue [2], the thrust ring is fixed to the casing with guide screws and is pressed against the sealing ring by at least one point spring.

The disadvantage of the analogue [2] is that the thrust ring is pressed against only one ring. This leads to extrusion of the material of the second ring, the gap between the rod and the chamber.

An oil seal with flat sealing elements is also known (Internet resource http://egineerinasystems.ru/trudi-mezhdunarodnoy-nauchno-tehnicheskoy-konferencii-po-kompressorostroyeniyu/analiz-raboti-shtoka.php, 01/15/2016, 15:33, [ 3]).

As in this technical solution, the specified analogue [3] contains chambers with sealing elements consisting of two split rings and two continuous support rings. Each of the split rings is surrounded by a bracelet spring, which makes a preliminary seal between the stuffing box ring and the stem. The second split ring in the direction of gas movement is made sealing and cut into six parts in such a way that short radial cuts are blocked by segments from above. The support rings are mounted on both sides in the bores of the split rings. Split rings are made of AFG-80 BC graphitofluoroplast. The support rings are made of PCB, in which chiffon is used as a filler.

In the indicated analogue [3], the first split ring in the direction of gas movement is made closing and cut into three parts. The closing ring does not prevent the passage of gas into the chamber and, being pressed by the gas pressure to the sealing ring, serves to block the cutouts of the sealing ring from the end face. The support rings are installed on the outer sides in the bores of the split locking and sealing rings. The indicated support rings are installed in relation to the stem with a guaranteed clearance. Between the outer surfaces of the support rings and the inner bores of the closing and sealing rings after manufacture, a gap is provided that is smaller in size than the gap between the support rings and the rod.

The first disadvantage of this analogue [3] is the deformation of split sealing and closing rings at large pressure drops. This reduces the tightness of the stem seal. When the pressure drop across the sealing element, for example, is 4 MPa, the split rings are pressed against the walls of the chamber with such force that it causes plastic deformation of the split rings. As a result of this deformation, the ring is so tightly attached to the chamber wall that it interferes with the self-installation of the stem during distortions, misalignment, and radial runout. The rod, trying to occupy the desired position for it, breaks the inner diameter of the split rings. At the same time, the gap between the stem and split rings increases, which leads to a decrease in the seal tightness. In addition, when the stem is self-installing between the split rings and the stem, friction increases. During friction, the material of the split rings is heated and extruded into the gap between the rod and the chamber.

The second disadvantage of this analogue [3] is that the first split ring in the direction of gas movement is made closing. Radial cuts at the closing ring are not blocked by segments (PI Plastinin, Piston compressors. Volume 2. Design fundamentals. Designs. - 3rd ed., Revised and additional - M .: KolosS, 2008. pp. 360-361 , Fig. 3.5.7, 6, [4]). Since the locking ring does not prevent the passage of gas into the chamber, the seal tightness is reduced.

The specified analogue [3] is the set of essential features the closest analogue of the same purpose to this technical solution. Therefore, it is adopted as a prototype.

Disclosure of the essence of the technical solution

The first technical result provided by this technical solution is to increase the tightness of the sealing device of the stem seal.

The second technical result is an increase in compressor performance.

The third technical result is the reduction in wear of the sealing rings of the stem seal.

The essence of the claimed technical solution lies in the fact that the sealing device of the stem seal contains at least one chamber in which the first and second split rings are placed, parts of which are pulled together by springs, the first and second continuous support rings that are installed on both sides of the split rings and made of a material more durable than the material of split rings. It differs in that:

- split rings and continuous support rings have the same outer diameters;

- split rings are made sealing, while the cuts of the sealing rings are closed and offset relative to each other in the angular direction;

- on each supporting ring, on the side facing the split ring, a concentric protrusion is made, the outer surface of which is completely covered by the cavity of the split ring.

The above essence is a combination of essential features of the claimed technical solution, ensuring the achievement of all the claimed technical results.

In special cases, it is permissible to carry out the technical solution as follows.

Depths in depth can be made at least up to the middle of the axial height of the rings.

Between the annular surfaces of the protrusions of the support rings and the annular surfaces of the depressions of the sealing rings, gaps are predominantly made smaller than the gaps between the support rings and the rod.

The axial height of the second support ring may be greater than the axial height of the first support ring, while the axial height of the second split ring is greater than the axial height of the first split ring.

The authors of the claimed technical solution made a prototype of this solution, the tests of which confirmed the achievement of technical results.

Brief Description of the Drawings

FIG. 1 shows a drawing of a sealing device for a stem seal; FIG. 2 - implementation of the support ring; in FIG. 3 - implementation of the sealing ring according to example 1; in FIG. 4 - implementation of the sealing ring according to example 2; FIG. 5 - implementation of the sealing device of the stem seal according to example 5.

Implementation of a technical solution.

The sealing device of the stem seal (Fig. 1) contains at least one chamber (1) in which the first split ring (2), the second split ring (3), the first continuous support ring (4), and the second continuous support ring (5) are placed ) and springs (6).

Split rings (2, 3) and continuous support rings (4, 5) have the same outer diameters. Continuous support rings (4, 5) are installed on both sides of the split rings (2, 3). The first support ring (4) closes from the end of the slot in the first split ring (2), which increases the tightness of the sealing device. During the period of expansion of gas from the dead space in the compressor cylinder and during the period of gas suction, the pressure in the stuffing box may be greater than the pressure in the cylinder, which leads to gas suction from the stuffing box and a decrease in compressor performance. The installation of the first support ring (4) on the side of the end face of the first split ring (2) eliminates this drawback, making the sealing device more airtight, which leads to an increase in compressor performance. Support rings (4, 5) additionally play the role of anti-extrusion rings.

The location of the support rings (4, 5) on both sides of the split rings (2, 3) allows both split rings (2, 3) to be sealed. The cuts of the sealing rings (2, 3) are overlapped and offset relative to each other in the angular direction. Since two sealing rings (2, 3) are installed in the chamber (1), more gaps are closed in comparison with the prototype [1]. This increases the seal tightness. Parts of the split rings (2, 3) are pulled together by springs (6), which pre-seal between the rings (2, 3) and the stem. The split rings (2, 3) are non-metallic, made of a self-lubricating material, for example, based on fluorone-4.

The material of the support rings (4, 5) should be more durable with respect to the sealing rings (2, 3). Due to the more durable material, the support rings (4, 5) do not undergo plastic deformation. For non-lubricated compressors, the support rings (4, 5) can be made, for example, from PCB grade Sh and grafelon. For compressors with limited lubrication and with lubrication, the support rings (4, 5) can be made, for example, of PCB grade Sh, grafelon, bronze.

On each supporting ring (4, 5), on the side facing the split ring (2, 3), a concentric protrusion (7) is made (Fig. 2), the outer surface (9) of which is covered by a cavity (8) (Fig. 3 ) split ring (2, 3). The outer surface (9) of the protrusion (7) consists of an end surface and an annular surface. Depressions (8) in depth are made at least to the middle of the axial height of the sealing rings (2, 3). In this case, the depth of the trough (8) of the split ring (2, 3) is greater than the height of the protrusion (7) of the support ring (4, 5).

The first and second support rings (4, 5) are installed in relation to the stem with a guaranteed clearance. Between the annular surfaces of the protrusions (7) of the support rings (4, 5) and the annular surfaces of the depressions (8) of the sealing rings (2, 3) after the manufacture of the packing, a radial clearance is provided that is smaller in size than the gap between the support rings (4, 5) and stock. After running in along the inner diameter, the sealing rings (2, 3) are supported by the protrusions (7) of the support rings (4, 5) and are not pressed against the stem. In addition, due to the presence of support rings (4, 5), the sealing rings (2, 3) are not pressed against the walls of the chamber (1). Thus, the sealing rings (2, 3) do not deform and retain the ability to move during runout and distortions of the stem. This increases the tightness of the sealing device of the stem seal and reduces the wear of the sealing rings of the stem seal.

Case Studies

Example 1. O-rings (2, 3) consist of four parts.

Example 2. Sealing rings (2, 3) consist of six parts (Fig. 4).

Example 3. If the gas compressed in the cylinder is wet, then the support rings (4, 5) can be made of graphelon-20, PCB Sh.

Example 4. If the gas compressed in the cylinder is dry, then the support rings (4, 5) can be made of graphelon-25M, textolite W.

Example 5. If the gas compressed in the cylinder is wet, then the sealing rings (2, 3) can be made of flubon-20.

Example 6. If the gas compressed in the cylinder is dry, then the sealing rings (2, 3) can be made of flubone - DM - 2.

Example 7. The axial height of the first support ring (5) is equal to the axial height of the second support ring (4).

Example 8. In order to increase the strength of the packing at high pressure differences acting on the sealing device, the axial height of the second support ring (5) is greater than the axial height of the first support ring (4). In this case, the axial height of the second split ring (3) is greater than the axial height of the first split ring (2) (Fig. 5).

Example 9. To ensure overlap of the joints, the sealing rings (2, 3) are mutually fixed with pins (not shown).

The implementation of the proposed technical solution is not limited to the above examples.

Work description

During compressor operation, split rings (2, 3) and support rings (4, 5) are pressed axially by the differential pressure to the end surface of the housing of the next chamber. In addition, split rings (2, 3) are pressed against the stem in the radial direction under the action of a differential pressure. If both split rings (2, 3) are made sealing, then the stem is sealed under pressure drops acting both in one direction and in the other. In the forward pressure differential, the main sealing ring is ring (3), and in the opposite direction of the differential pressure, the main sealing ring is ring (2).

The support rings (4, 5) do not allow the sealing rings (2, 3) to press against the walls of the chamber (1). As a result, there is no deformation of the sealing rings (2, 3). In addition, there is no extrusion of the material of the sealing rings (2, 3) into the gap between the chamber (1) and the rod. In this case, as the sealing rings (2, 3) are run-in to the stem, the radial gaps between the annular surfaces of the protrusions (7) of the support rings (4, 5) and the annular surfaces of the depressions (8) of the sealing rings (2, 3) are eliminated. After that, the sealing rings (2, 3) tightly enclose the protrusions (7) of the support rings (4, 5) with their depressions (8). As a result of this, there is no further pressing of the sealing rings (2, 3) to the stem. This reduces the wear of the sealing rings (2, 3) of the stem seal, reduces friction losses and increases the tightness of the sealing device of the stem seal.

Industrial applicability

This technical solution is implemented using industrially produced devices and materials, can be manufactured at any industrial enterprise and will be widely used in sealing technology for sealing the compressor cylinder.

Claims (7)

1. The sealing device of the stem seal containing at least one chamber in which the first and second split rings are placed, parts of which are pulled together by springs, the first and second continuous support rings, which are installed on both sides of the split rings and are made of a material that is more durable than the material of the split rings, characterized in that - split rings and continuous support rings have the same outer diameters; - split rings are made sealing, while the cuts of the sealing rings are closed and offset relative to each other in the angular direction; - on each supporting ring on the side facing the split ring, a concentric protrusion is made, the outer surface of which is completely covered by the cavity of the split ring. 2. A sealing device according to claim 1, characterized in that the hollows in depth are made at least to the middle of the axial height of the rings. 3. The sealing device according to claim 1, characterized in that between the annular surfaces of the protrusions of the support rings and the annular surfaces of the depressions of the sealing rings, gaps are made that are smaller than the gaps between the support rings and the rod. 4. The sealing device according to claim 1, characterized in that the axial height of the second support ring is greater than the axial height of the first support ring, while the axial height of the second split ring is greater than the axial height of the first split ring.

Images