CN115773245A

CN115773245A - Mechanical seal for screw compressor

Info

Publication number: CN115773245A
Application number: CN202211696579.0A
Authority: CN
Inventors: 蒋敏; 吴磊波
Original assignee: NINGBO TIANGONG MACHINERY SEALING CO LTD
Current assignee: NINGBO TIANGONG MACHINERY SEALING CO LTD
Priority date: 2022-12-28
Filing date: 2022-12-28
Publication date: 2023-03-10

Abstract

The invention provides a mechanical seal for a screw compressor, which comprises a shaft sleeve, a gland, a main seal and an auxiliary seal, wherein the main seal and the auxiliary seal are assembled between the shaft sleeve and the gland; a lip seal is arranged on the inner cavity wall of the gland close to the medium end, corresponding to the mounting boss at one end of the shaft sleeve, the inner ring of the lip seal is hermetically sleeved on the outer wall of the mounting boss, so that a sealing cavity is formed between the outer side of the main seal and the inner cavity wall of the gland, a liquid inlet hole and a liquid outlet hole which are respectively communicated with the sealing cavity are formed in the gland, a flow guide part is arranged on the inner cavity wall of the gland, so that flushing liquid in the liquid inlet hole directly washes the outer side of a friction pair of the main seal, and the liquid inlet hole and the liquid outlet hole are axially positioned on two sides of the flow guide part; an exhaust port communicated with the isolation cavity is formed in the side wall of the gland. The mechanical seal for the screw compressor disclosed by the invention can effectively realize lubricating oil seal and can realize stable seal of a refrigerant.

Description

Mechanical seal for screw compressor

Technical Field

The invention relates to the technical field of mechanical seals, in particular to a mechanical seal for a screw compressor.

Background

The mechanical seal is a shaft seal of a rotating machine, and since a rotating shaft penetrates inside and outside the equipment, a circumferential gap exists between the shaft and the equipment, a medium in the equipment leaks outwards through the gap, and if the pressure in the equipment is lower than the atmospheric pressure, air leaks into the equipment, so that a shaft seal for preventing the leakage is needed. The shaft seal has many kinds, and the mechanical seal has advantages such as a small leakage amount and a long life, and therefore the mechanical seal is the most important shaft seal system in these devices.

The excellent versatility of screw compressors, both centrifugal and piston compressors, while avoiding their disadvantages, makes them well suited for use throughout the world from very small chemical processes to large-scale plants. Therefore, process screw compressors are preferred in many operations and processes in the chemical and petrochemical industries, while oil-injected twin screw compressors have the advantages of high reliability and low operating costs, which are ideal compression equipment for process gases and applications. At present, a screw compressor exists, the medium of the screw compressor is lubricating oil containing 20% -30% of refrigerants, the operation rotating speed reaches 3000-5000RPM, the pressure can reach 1.5MPa, the existing mechanical seal of the compressor can seal the lubricating oil, but the sealing effect of the refrigerant is not ideal, the pressure fluctuation of a sealing cavity of the compressor is obvious, and certain requirements are met for the pressure regulating performance of the mechanical seal.

Disclosure of Invention

The invention solves the problems that: the mechanical seal for the screw compressor overcomes at least one defect in the prior art, can effectively realize lubricating oil sealing, and can realize stable sealing of a refrigerant.

In order to solve the problems, the invention provides a mechanical seal for a screw compressor, which comprises a shaft sleeve and a gland sleeved outside the shaft sleeve, wherein a main seal is arranged between one end of the shaft sleeve, which is close to a medium, and one end of the shaft sleeve, which is close to the atmosphere, and the other end of the shaft sleeve, which is close to the atmosphere, and an auxiliary seal is arranged between the other end of the shaft sleeve and the inner cavity of the gland, so that an isolation cavity is formed between the outside of the shaft sleeve and the inner cavity of the gland; the inner cavity wall of the gland is provided with a lip seal at a position corresponding to the mounting boss, the inner ring seal of the lip seal is sleeved on the outer wall of the mounting boss so as to form a seal cavity between the outer side of the main seal and the inner cavity wall of the gland, the gland is provided with a liquid inlet hole and a liquid outlet hole which are respectively communicated with the seal cavity, the inner cavity wall of the gland is provided with a flow guide part so that a flushing liquid in the liquid inlet hole can directly flush the outer side of a friction pair of the main seal, and the liquid inlet hole and the liquid outlet hole are axially positioned at two sides of the flow guide part; and an exhaust port communicated with the isolation cavity is formed in the side wall of the gland.

Compared with the prior art, the invention has the advantages that:

in the mechanical sealing structure, a double-end-face series design structure is adopted, the main seal is in a contact type, the auxiliary seal is in a non-contact type, and specifically, the main seal directly contacts a medium, and the medium enters a grinding surface of the main seal to form a wet liquid film during operation of the mechanical sealing structure, so that the sealing performance is realized; an isolation cavity is arranged between the auxiliary seal and the main seal, but no buffer solution is added in the isolation cavity, namely, a dry environment is always kept, so that a liquid film is not generated between the grinding surfaces of the auxiliary seal, the isolation cavity is a dry gas seal, and when a rotating shaft of a compressor rotates highly, a gas film is formed between the grinding surfaces of the auxiliary seal and is used for emergently sealing a medium leaked from the main seal in the isolation cavity; more specifically, in the scheme of the invention, the lip seal structure is arranged at the medium end, and the seal cavity is formed between the lip seal and the outer side of the main seal, so that the lip seal plays a role in sealing when the compressor normally works, and stable pressure can be established at the main seal cavity by matching with the liquid outlet hole, so that the refrigerant can not be released due to pressure reduction; when the pressure of the sealing cavity is suddenly increased, the lip seal can be opened under the pushing of high pressure to release pressure, and the effect of preventing the machine seal from being damaged due to sudden high pressure is achieved. The end, close to the medium, in the gland is provided with a throttling and pressure regulating structure design, so that the double sealing performance of the mechanical seal on lubricating oil and a refrigerant is effectively improved; and leakage collection is arranged outside the gland, namely, the refrigerant leaked out of the main seal part can be discharged through an exhaust port and is connected to the combustor to be combusted.

As an improvement, the flow guide part is an annular flow guide sleeve, the radial outer end of the flow guide sleeve is connected with the inner cavity wall of the gland, the radial inner end of the flow guide sleeve extends towards the main seal, and a channel is reserved between the inner side wall of the flow guide sleeve and the outer side wall of the main seal; the radial outer end of the flow guide sleeve is provided with an exhaust hole which is communicated along the axial direction of the flow guide sleeve. In the improved structure, the flow guide sleeve is used for guiding the flushing liquid to align to the position of the main sealing surface, so that the cooling effect is improved, and the service life of the seal is prolonged; in addition, the setting of exhaust hole prevents effectively that sealed chamber from influencing the leakproofness because of gas gathering.

In a further improvement, the inner cavity wall of the end of the gland close to the medium is provided with two positioning clamping grooves distributed along the axial direction of the gland, and clamping springs are arranged in the two positioning clamping grooves; one end of the lip seal is axially abutted against one end of the flow guide sleeve, and the other ends of the lip seal and the flow guide sleeve are respectively abutted and limited with the two clamp springs along the axial direction. In the above-mentioned improved structure, lip seal and water conservancy diversion cover pass through two jump rings location connection in the inner chamber of gland, simple structure, simple to operate.

And the inner end of the positioning pin is assembled in the positioning hole. In the above-mentioned improved structure, the setting of locating pin and locating hole realizes that the circumference of water conservancy diversion cover prevents changeing spacing effect, also can play the spacing effect of axial antiskid simultaneously.

The main seal comprises a driving ring and a main static ring component, wherein one end of the mounting boss, which is far away from the medium, is provided with a dynamic ring groove, one end of the driving ring is assembled in the dynamic ring groove, one end of the main static ring component is assembled in the first mounting groove, and the other end of the main static ring component is abutted with the other end of the driving ring in a manner of relative rotation along the circumferential direction, so as to form a main friction pair; and an elastic compensation element is assembled between the first mounting groove and the main static ring component.

The main stationary ring assembly comprises a main stationary ring, a main stationary ring seat and a first positioning ring, wherein the main stationary ring seat comprises a bottom plate and a positioning sleeve, the positioning sleeve is axially formed at the radial inner end of the bottom plate, the bottom plate is assembled in the first mounting groove, a plurality of connecting bolts are movably arranged on the bottom plate in a penetrating manner, the first positioning ring is positioned at one side of the bottom plate, which is far away from the first mounting groove, and a plurality of threaded holes respectively connected with the connecting bolts are formed in the first positioning ring; the radial outer end of the first positioning ring is provided with an anti-rotation lug, the radial outer side wall of the main static ring is provided with an anti-rotation groove matched with the anti-rotation lug, the radial inner side of the main static ring is hermetically matched in the positioning sleeve, and the end part of the main static ring is abutted against the first positioning ring; and a first elastic compensation element is assembled between the first positioning ring and the bottom plate.

In another improvement, the secondary seal includes a secondary moving ring and a secondary stationary ring, a driving ring is sleeved outside one end of the shaft sleeve close to the atmosphere, one end of the driving ring extends towards one end of the isolation cavity to form a mounting sleeve, and the secondary moving ring is sleeved outside the mounting sleeve; the end part of the gland close to the atmosphere side is connected with an end cover, one side of the end cover close to the isolation cavity is provided with a static ring groove, one end of the auxiliary static ring is assembled in the static ring groove, and the other end of the auxiliary static ring is abutted against one end of the auxiliary rotating ring in a circumferential direction in a relatively rotatable manner so as to form an auxiliary friction pair; and a second elastic compensation element is arranged between the auxiliary static ring and the end cover.

And the two ends of the auxiliary rotating ring are respectively abutted and limited between the limiting sleeve and the limiting step.

In another improvement, a second positioning ring is assembled between the end faces of the static ring groove and the auxiliary static ring, and the second elastic compensation element is arranged between the static ring groove and the second positioning ring; the bottom surface of the static ring groove is provided with an anti-rotation pin, and the outer walls of the second positioning ring and the auxiliary static ring are provided with anti-rotation grooves matched with the anti-rotation pin.

Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

FIG. 1 is a schematic view of a half-section of a mechanical seal for a screw compressor according to the present invention;

FIG. 2 is an enlarged view of the structure at X in FIG. 1;

FIG. 3 is an enlarged view of the structure at Y in FIG. 1;

FIG. 4 is a schematic view of a secondary seal structure of the present invention;

fig. 5 is a partial schematic view of a structure of a clasping pressing block at one end of the shaft sleeve.

Description of reference numerals:

1. a shaft sleeve; 2. a gland; 3. an isolation chamber; 4. mounting a boss; 5. a first mounting groove; 6. sealing the lips; 7. sealing the cavity; 8. a liquid inlet hole; 9. a liquid outlet hole; 10. a flow guide sleeve; 11. an exhaust hole; 12. positioning a clamping groove; 13. a clamp spring; 14. positioning holes; 15. positioning pins; 16. an exhaust port; 17. a driving ring; 18. a movable ring groove; 19. a main stationary ring; 20. a main stationary ring seat; 21. a first positioning ring; 22. a base plate; 23. a positioning sleeve; 24. a connecting bolt; 25. an anti-rotation lug; 26. an anti-rotation groove; 27. an auxiliary movable ring; 28. a secondary stationary ring; 29. a drive ring; 30. installing a sleeve; 31. an end cap; 32. a static ring groove; 33. a limiting boss; 34. a limiting sleeve; 35. a second positioning ring; 36. an anti-rotation pin; 37. a first spring; 38. a first spring hole; 39. a second mounting groove; 40. a second spring; 41. a second spring hole; 42. a first connection hole; 43. a set screw; 44. positioning the convex column; 45. a positioning groove; 46. a second connection hole; 47. a drive screw; 48. a transmission groove; 49. tightly holding a pressing block; 50. an air inlet.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

In the description of the present invention, it should be noted that the terms "outer end", "inner side wall", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for convenience of description and simplification of the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and operate, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" in the description are used for convenience of distinguishing and understanding only, and do not have a specific meaning or definition. The tail end refers to an end of the moving ring, which faces away from the friction surface, for example, the tail end of the moving ring refers to an end of the moving ring, which faces away from the friction surface.

In the description of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the term "connected" is to be interpreted broadly, e.g. as a fixed connection, a detachable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

As shown in fig. 1, the invention provides a mechanical seal for a screw compressor, which comprises a shaft sleeve 1 sleeved outside a rotating shaft of the compressor, wherein a seal ring is arranged between the inner wall of one end of the shaft sleeve 1 and the outer wall of the rotating shaft; the external cover of axle sleeve 1 is equipped with gland 2, and gland 2 is used for being connected fixedly with the installation cavity of compressor.

In addition, a main seal is arranged between one end of the shaft sleeve 1 close to the medium and one end of the inner cavity of the gland 2, and an auxiliary seal is arranged between one end of the shaft sleeve 1 close to the atmosphere and the other end of the inner cavity of the gland 2, so that an isolation cavity 3 is formed between the outer part of the shaft sleeve 1 and the inner cavity of the gland 2; specifically, the main seal in the structure is mainly used for realizing the primary seal of the medium end, once the main seal leaks, part of the medium enters the isolation cavity 3 chamber, and the auxiliary seal can be used as an emergency seal at the moment, so that the double-end-face sealing structure can keep more stable sealing performance.

Specifically, as shown in fig. 2, in this embodiment, an installation boss 4 is disposed at one end of the shaft sleeve 1 close to the medium, a first installation groove 5 is disposed at one end of the inner cavity of the gland 2, one end of the main seal is assembled at one end of the installation boss 4 far away from the medium, and the other end is assembled in the first installation groove 5; a lip seal 6 is arranged on the inner cavity wall of the gland 2 at a position corresponding to the mounting boss 4, wherein the inner ring of the lip seal 6 is hermetically sleeved on the outer wall of the mounting boss 4, so that a sealing cavity 7 is formed between the outer side of the main seal and the inner cavity wall of the gland 2; on the other hand again, set up respectively with the feed liquor hole 8 and the play liquid hole 9 of sealed chamber 7 intercommunication on gland 2, and be provided with water conservancy diversion portion on gland 2's the inner chamber wall, so that the vice outside of main sealed friction can directly be washed to the flush fluid in feed liquor hole 8, effectively promote the cooling efficiency to the friction surface, and feed liquor hole 8 in this structure, go out liquid hole 9 and lie in the both sides of water conservancy diversion portion along the axial, simultaneously under the effect of water conservancy diversion portion, assurance coolant liquid and sealed face contact time that can be better, promote the cooling from another angle, the radiating effect.

On the other hand, in the structure, the lip seal 6 plays a role in sealing when the compressor works normally, and stable pressure can be established at the main sealing cavity 7 by matching with the liquid outlet hole 9, so that the refrigerant is not released due to pressure reduction; when the pressure of the seal cavity 7 is suddenly increased, the lip seal 6 is opened to release the pressure under the pushing of high pressure, and the function of preventing the machine seal from being damaged due to the sudden high pressure is achieved.

In this embodiment, the preferable flow guiding portion is an annular flow guiding sleeve 10, a radial outer end of the flow guiding sleeve 10 is connected with an inner cavity wall of the gland 2, a radial inner end of the flow guiding sleeve 10 extends towards the main seal, and a channel is reserved between an inner side wall of the flow guiding sleeve 10 and an outer side wall of the main seal for a cooling liquid to pass through; on the other hand, the radial outer end of the flow guide sleeve 10 is provided with an exhaust hole 11 which is through along the axial direction of the flow guide sleeve, so that the sealing cavity 7 is prevented from influencing the sealing performance due to gas accumulation.

More specifically, in this embodiment, an inclined plane is disposed on a main stationary ring 19 (described in detail later) of the main sealing structure, one side of the flow guiding sleeve 10 close to the inclined plane is parallel to the inclined plane to form an inclined flushing channel, and the central axis of the liquid inlet hole 8 is parallel to the inclined plane, so that the flushing liquid is flushed along an angle tangent to the inclined plane, thereby improving the efficiency.

Two positioning clamping grooves 12 distributed along the axial direction of the inner cavity wall at one end of the gland 2 close to the medium are formed in the inner cavity wall, and clamping springs 13 are arranged in the two positioning clamping grooves 12; one end of the lip seal 6 is axially abutted against one end of the flow guide sleeve 10, and the other ends of the lip seal 6 and the flow guide sleeve 10 are respectively abutted against and limited by the two clamp springs 13 along the axial direction; and the outer wall of the flow guide sleeve 10 is provided with a positioning hole 14, the side wall of the gland 2 is provided with a positioning pin 15 in a penetrating way, and the inner end of the positioning pin 15 is assembled in the positioning hole 14, so that the circumferential anti-rotation limit of the flow guide sleeve 10 is realized, and the axial anti-skid limit can also be realized. More specifically, the rubber sealing strip portion at the position of the structure is in sealing fit on the outer wall of the mounting boss 4 towards the bending direction of the medium end, when the pressure of the sealing cavity 7 is too high, the rubber sealing strip can be pushed away along the bending direction to form an air leakage channel, and the surface main seal is damaged due to the too high pressure. In addition, in the structure, a wear-resistant coating is added on the outer wall of the mounting boss 4 at a position corresponding to the rubber sealing strip.

As shown in fig. 1, in the present embodiment, a vent 16 communicating with the isolation chamber 3 is formed on the sidewall of the gland 2, so that the refrigerant leaking from the primary seal can be discharged through the vent 16 at regular time and burned by the burner.

The following is a detailed description of the structure of the primary seal and the secondary seal:

the main seal comprises a driving ring 17 and a main static ring component, a movable ring groove 18 is formed in one end, far away from a medium, of the mounting boss 4, one end of the driving ring 17 is assembled in the movable ring groove 18, axial limiting of the driving ring 17 is achieved by clamping the corresponding positioning clamping ring on the outer wall of the shaft sleeve 1, and the driving ring 17 is prevented from being separated from the movable ring groove 18. One end of the main static ring component is assembled in the first mounting groove 5, and the other end of the main static ring component is abutted against the other end of the driving ring 17 in a manner of relative rotation along the circumferential direction so as to form a main friction pair; more specifically, the main stationary ring assembly comprises a main stationary ring 19, a main stationary ring seat 20 and a first positioning ring 21, the main stationary ring seat 20 comprises a bottom plate 22 and a positioning sleeve 23, the positioning sleeve 23 is axially formed at the radial inner end of the bottom plate 22, the bottom plate 22 is assembled in the first mounting groove 5, and the bottom plate 22 is axially connected in the first mounting groove 5 through a connecting screw; in addition, as shown in fig. 3, a plurality of connecting bolts 24 are movably arranged on the bottom plate 22 in a penetrating manner, the first positioning ring 21 is positioned on one side of the bottom plate 22 far away from the first mounting groove 5, and a plurality of threaded holes respectively connected with the connecting bolts 24 are formed in the first positioning ring 21; the radial outer end of the first positioning ring 21 is provided with an anti-rotation lug 25, and the radial outer side wall of the main stationary ring 19 is provided with an anti-rotation groove 26 matched with the anti-rotation lug 25, so that circumferential anti-rotation of the main stationary ring 19 is realized.

Otherwise, as shown in fig. 2. The radial inner side of the main static ring 19 is hermetically assembled in the positioning sleeve 23, and the end part of the main static ring 19 is abutted with the first positioning ring 21; the first elastic compensation element is assembled between the first positioning ring 21 and the bottom plate 22, so that the main static ring 19 always has a tendency of moving towards one side of the driving ring 17, namely, in the process of using and wearing the main sealing grinding surface, under the elastic action of the first elastic compensation element, the main static ring 19 can always keep the sealing fit with the driving ring 17, and the stability of the sealing performance is ensured. In addition, a static ring compensation type structure is adopted in the structure, and the static ring part is static, so that the compensation structure can bear higher rotating speed. Preferably, the first elastic compensation element includes a plurality of first springs 37, a plurality of first spring holes 38 are formed in the bottom plate 22, the first spring holes 38 are circumferentially and uniformly distributed, one end of each first spring 37 abuts against and is assembled in the corresponding first spring hole 38, and the other end of each first spring 37 abuts against an end surface of the first positioning ring 21, as shown in fig. 2.

As shown in figure 1, the washing liquid accessed by the liquid inlet hole 8 in the structure can realize the cooling and washing of the main seal, and can also carry out the washing of the first spring 37, thereby avoiding the unstable elastic compensation force caused by the accumulated impurities of the first spring 37.

The setting of first retainer ring 21 makes the installation of main quiet ring 19 more convenient in this embodiment structure to at the axial displacement in-process of main quiet ring 19, each connecting bolt 24 can play the guide effect, guarantees the stationarity of sliding. And the first positioning ring 21 is connected with the bottom plate 22 through the connecting bolt 24 to form an integral structure, so that the mechanical seal is convenient to assemble, namely, before the integral mechanical seal is assembled, the main static ring 19, the first positioning ring 21 and the bottom plate 22 can be preassembled in the integral assembly structure, the loss of parts during assembly is avoided, the installation efficiency is improved, the probability of neglected assembly of the parts is reduced, and the final sealing effect of a product is ensured.

In this embodiment, the driving ring 17 and the main stationary ring 19 are made of silicon carbide, and compared with the conventional silicon carbide-graphite pairing structure, the graphite pairing structure is flash-exploded due to expansion of the refrigerant when heated, so that the graphite ring is low in strength and easy to damage, and the silicon carbide does not have the problem.

In addition, as shown in fig. 4, the secondary seal comprises a secondary rotating ring 27 and a secondary stationary ring 28, the outside of the end of the shaft sleeve 1 near the atmosphere is sleeved with a driving ring 29, one end of the driving ring 29 extends towards one end of the isolation cavity 3 to form a mounting sleeve 30, and the secondary rotating ring 27 is sleeved outside the mounting sleeve 30; specifically, an annular limiting boss 33 is arranged on the outer wall of the mounting sleeve 30, a limiting sleeve 34 is arranged at one end, away from the driving ring 29, of the mounting sleeve 30, and the limiting sleeve 34 is connected to the outside of the mounting sleeve 30 in a threaded fit mode, so that two ends of the auxiliary moving ring 27 are respectively abutted against and limited between the limiting sleeve 34 and a limiting step, connection between the auxiliary moving ring 27 and the mounting sleeve 30 is achieved, and a corresponding sealing ring is assembled between the inner wall of the auxiliary moving ring 27 and the outer wall of the mounting sleeve 30. In addition, a second mounting groove 39 is arranged at the end part of the gland 2 close to the atmosphere side, an end cover 31 is assembled in the second mounting groove 39, the radial outer end of the cover plate is fixedly connected with the end surface of the gland 2 through a screw, an annular static ring groove 32 is arranged at the radial inner end of the end cover 31 and one side close to the isolation cavity 3, one end of an auxiliary static ring 28 is assembled in the static ring groove 32, and the other end of the auxiliary static ring 28 is abutted with one end of an auxiliary movable ring 27 in a circumferential direction in a relatively rotatable manner to form an auxiliary friction pair; and a second elastic compensation element is arranged between the auxiliary static ring 28 and the end cover 31, so that the auxiliary static ring 28 always has the tendency of moving towards the side of the auxiliary movable ring 27, and the sealing performance of the sealing surface is better ensured.

More specifically, in the above structure, a second positioning ring 35 is fitted between the end surface of the stationary ring groove 32 and the end surface of the auxiliary stationary ring 28, and the second elastic compensation element is disposed between the stationary ring groove 32 and the second positioning ring 35; an anti-rotation pin 36 is arranged on the bottom surface of the static ring groove 32, and anti-rotation grooves 26 matched with the anti-rotation pin 36 are formed in the outer walls of the second positioning ring 35 and the auxiliary static ring 28; and one side that is close to vice stationary ring 28 at the radial inner of second holding ring 35 is equipped with the sealing washer groove, is equipped with the sealing washer at the outside cover in the vertical limit of stationary ring groove 32, and the sealing washer is fixed a position between the terminal surface of sealing washer groove and vice stationary ring 28 along the axial of installing sleeve 30, realizes the sealing connection of vice stationary ring 28 and end cover 31 to the sealing washer has stable spacing, can not take place to remove. Similarly, the second elastic compensation element in this structure includes a plurality of second springs 40, a plurality of second spring holes 41 are opened at one end of the end cover 31, one ends of the plurality of second springs 40 are respectively abutted and fitted in the second spring holes 41, and the other ends of the plurality of second springs 40 are respectively abutted on the second positioning ring 35, so as to realize axial elastic compensation of the secondary stationary ring 28, as shown in fig. 4.

In the above structure, a plurality of first connection holes 42 distributed along the circumferential direction are formed in the side wall of the driving ring 29, a set screw 43 is assembled in each first connection hole 42, a positioning convex column 44 is arranged at the end of each set screw 43, and a plurality of positioning grooves 45 matched with each positioning convex column 44 are correspondingly formed in the outer wall of the shaft sleeve 1; when the driving ring 29 is sleeved on the outer wall of the shaft sleeve 1 and moves axially to a set position, the driving ring 29 and the shaft sleeve 1 are prepositioned by a plurality of fastening screws 43 to form an integral structure; in addition, a plurality of second connecting holes 46 which are staggered with the first connecting blocks are further formed in the side wall of the driving ring 29, a transmission screw 47 is assembled in each second connecting hole 46, a transmission groove 48 is correspondingly formed in the outer wall of the shaft sleeve 1 and corresponds to the position of each transmission screw 47, when the whole set of mechanical seal is installed outside the rotating shaft to a set position, the second transmission screws 47 are screwed, the end portions of the transmission screws 47 drive the side wall of the shaft sleeve 1 to deform slightly, and accordingly a holding effect is achieved. More specifically, in order to make the side wall of the shaft sleeve 1 easy to deform and hold tightly, notches are formed at two circumferential sides of each transmission groove 48 at the end part of the shaft sleeve 1 to form a plurality of deformable holding pressing blocks 49, as shown in fig. 5.

In this embodiment, the secondary seal adopts dry gas seal, that is, there is no medium lubrication on the wear surface of the secondary seal, and there is no isolation liquid in the isolation cavity 3, so that under the high-speed operation of the mechanical seal, a certain gas film is generated between the secondary rotating ring 27 and the secondary stationary ring 28, and once the primary seal leaks, the medium enters the isolation cavity 3, and the leaked medium can be sealed by the gas film. And the side wall of the gland 2 is also provided with an air inlet 50, namely, gas with certain pressure can be introduced into the isolation cavity 3, so that a high-pressure cavity is formed in the isolation cavity 3, and when the pressure of the isolation cavity 3 is higher than that of the sealing cavity 7, the effect of preventing media at the main sealing part from leaking to the isolation cavity 3 can be achieved.

Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and such changes and modifications will fall within the scope of the present disclosure.

Claims

1. The utility model provides a mechanical seal for screw compressor, includes axle sleeve (1) and suit axle sleeve (1) outside gland (2), axle sleeve (1) be close to the medium one end with be provided with the main seal between the one end of gland (2) inner chamber, axle sleeve (1) be close to atmospheric one end with be equipped with vice sealed between the other end of gland (2) inner chamber, so that axle sleeve (1) outside with form between gland (2) inner chamber and keep apart chamber (3), its characterized in that:

an installation boss (4) is arranged at one end, close to a medium, of the shaft sleeve (1), a first installation groove (5) is formed at one end of an inner cavity of the gland (2), one end of the main seal is assembled at one end, far away from the medium, of the installation boss (4), and the other end of the main seal is assembled in the first installation groove (5); a lip seal (6) is arranged on the inner cavity wall of the gland (2) corresponding to the mounting boss (4), the inner ring of the lip seal (6) is sleeved on the outer wall of the mounting boss (4) in a sealing manner, so that a sealing cavity (7) is formed between the outer side of the main seal and the inner cavity wall of the gland (2), a liquid inlet hole (8) and a liquid outlet hole (9) which are respectively communicated with the sealing cavity (7) are formed in the gland (2), a flow guide part is arranged on the inner cavity wall of the gland (2), so that flushing liquid in the liquid inlet hole (8) can directly flush the outer side of a friction pair of the main seal, and the liquid inlet hole (8) and the liquid outlet hole (9) are axially positioned on two sides of the flow guide part; and an exhaust port (16) communicated with the isolation cavity (3) is formed in the side wall of the gland (2).

2. The mechanical seal for a screw compressor according to claim 1, wherein: the flow guide part is an annular flow guide sleeve (10), the radial outer end of the flow guide sleeve (10) is connected with the inner cavity wall of the gland (2), the radial inner end of the flow guide sleeve (10) extends towards the main seal, and a channel is reserved between the inner side wall of the flow guide sleeve (10) and the outer side wall of the main seal; the radial outer end of the flow guide sleeve (10) is provided with an exhaust hole (11) which is communicated along the axial direction.

3. The mechanical seal for a screw compressor according to claim 2, wherein: the inner cavity wall of one end, close to the medium, of the gland (2) is provided with two positioning clamping grooves which are distributed along the axial direction of the gland, and clamping springs (13) are arranged in the two positioning clamping grooves; one end of the lip seal (6) is axially abutted against one end of the flow guide sleeve (10), and the other ends of the lip seal (6) and the flow guide sleeve (10) are respectively abutted against and limited by the two clamp springs (13) along the axial direction.

4. The mechanical seal for a screw compressor according to claim 3, wherein: the outer wall of the flow guide sleeve (10) is provided with a positioning hole (14), the side wall of the gland (2) is provided with a positioning pin (15) in a penetrating mode, and the inner end of the positioning pin (15) is assembled in the positioning hole (14).

5. The mechanical seal for the screw compressor according to any one of claims 1 to 4, characterized in that: the main seal includes drive ring (17) and main quiet ring (19) subassembly, mounting boss (4) are kept away from the one end of medium and have been seted up movable ring groove (18), the one end of drive ring (17) is joined in marriage the dress and is in movable ring groove (18), the one end of main quiet ring (19) subassembly is joined in marriage the dress in first mounting groove (5), the other end of main quiet ring (19) subassembly with the butt that circumference can relatively rotate is followed to the other end of drive ring (17) to it is vice to form main friction.

6. The mechanical seal for a screw compressor according to claim 5, wherein: the main static ring (19) assembly comprises a main static ring (19), a main static ring seat (20) and a first positioning ring (21), the main static ring seat (20) comprises a bottom plate (22) and a positioning sleeve (23), the positioning sleeve (23) is axially formed at the radial inner end of the bottom plate (22), the bottom plate (22) is assembled in the first mounting groove (5), a plurality of connecting bolts (24) are movably arranged on the bottom plate (22) in a penetrating mode, the first positioning ring (21) is located on one side, away from the first mounting groove (5), of the bottom plate (22), and a plurality of threaded holes connected with the connecting bolts (24) are formed in the first positioning ring (21); an anti-rotation lug (25) is arranged at the radial outer end of the first positioning ring (21), an anti-rotation groove (26) matched with the anti-rotation lug (25) is arranged on the radial outer side wall of the main static ring (19), the radial inner side of the main static ring (19) is hermetically assembled in the positioning sleeve (23), and the end part of the main static ring (19) is abutted to the first positioning ring (21); a first elastic compensation element is arranged between the first positioning ring (21) and the bottom plate (22).

7. The mechanical seal for a screw compressor according to claim 1, wherein: the auxiliary seal comprises an auxiliary movable ring (27) and an auxiliary stationary ring (28), a driving ring (29) is sleeved outside one end, close to the atmosphere, of the shaft sleeve (1), one end of the driving ring (29) extends towards one end of the isolation cavity (3) to form a mounting sleeve (30), and the auxiliary movable ring (27) is sleeved outside the mounting sleeve (30); the end part of the gland (2) close to the atmosphere side is connected with an end cover (31), one side of the end cover (31) close to the isolation cavity (3) is provided with a static ring groove (32), one end of the auxiliary static ring (28) is assembled in the static ring groove (32), and the other end of the auxiliary static ring (28) is abutted to one end of the auxiliary dynamic ring (27) in a manner of relative rotation along the circumferential direction so as to form an auxiliary friction pair; a second elastic compensation element is arranged between the auxiliary static ring (28) and the end cover (31).

8. The mechanical seal for a screw compressor according to claim 7, wherein: the outer wall of the mounting sleeve (30) is provided with a limiting boss (33), one end of the mounting sleeve (30) far away from the driving ring (29) is in threaded fit with a limiting sleeve (34), and two ends of the auxiliary moving ring (27) are respectively abutted against and limited between the limiting sleeve (34) and the limiting step.

9. The mechanical seal for a screw compressor according to claim 8, wherein: a second positioning ring (35) is assembled between the static ring groove (32) and the end face of the auxiliary static ring (28), and the second elastic compensation element is arranged between the static ring groove (32) and the second positioning ring (35); be provided with on the bottom surface of quiet annular (32) and prevent changeing round pin (36), all seted up on the outer wall of second holding ring (35) and vice quiet ring (28) with prevent changeing recess (26) of changeing round pin (36) complex.