Double-end-face sealing device for screw compressor

Abstract

The utility model provides a double-end-face sealing device for a screw compressor, which relates to the field of mechanical sealing and comprises a shaft sleeve and a sealing seat, a movable ring seat is arranged on the outer wall of one end of the shaft sleeve, a wet-type main seal is assembled between one end of the sealing seat and the movable ring seat, and a dry gas sealing component is arranged between the other end of the sealing seat and the other end of the shaft sleeve; a second mounting groove is formed in the inner side of the end, away from the shell, of the sealing seat, an air inlet and an air outlet which communicate with the second mounting groove are formed in the sealing seat, and a throttling assembly is arranged between the inner wall of the sealing seat and the outer wall of the shaft sleeve; the end, located in the shell, of the sealing base is connected with a flushing sleeve, an oil inlet and an oil outlet are formed in the flushing sleeve, and a lip seal used for preventing oil in the screw cavity from reversely entering the flushing sleeve is arranged between the inner wall of the end, away from the sealing base, of the flushing sleeve and the outer wall of the shaft sleeve. The double-end-face sealing device for the screw compressor is stable in sealing performance and long in service life, and especially can effectively seal flammable and explosive working conditions.

Description

Technical Field

[0001] The utility model relates to the technical field of mechanical seals, in particular to a double-end face sealing device for a screw compressor. Background Art

[0002] Twin-screw compressors can be divided into refrigeration compressors and process gas compressors according to different usage conditions. The former mainly uses refrigerant as the refrigeration medium and compresses the refrigerant through two rotating screws, thereby realizing the core process of the entire refrigeration process. The process gas compressor achieves precise gas compression through two intermeshing rotating screws, which continuously engage and disengage during high-speed rotation to compress the gas to the required pressure and temperature. The advantages of twin-screw compressors are high working efficiency, high energy utilization, low noise, low vibration, good stability, and light weight. These technologies are widely used in air compressors, industrial pumps, refrigerators, condensers and other fields, providing strong support for industrial production and manufacturing.

[0003] Commonly used shaft seals for twin-screw compressors include packing seals, labyrinth seals, and mechanical seals, and mechanical seals are currently the most mainstream form of sealing. Traditional mechanical seal structures have good adaptability and life for traditional refrigeration or process gas compressors, and are also the mainstream in the current market. However, in flammable and explosive process gas compressors, packing seals have large leakage, and labyrinth seals also have the risk of large leakage, so they must not be used. Traditional mechanical seals often use double-end faces and isolation liquid or buffer for flushing and cooling. The auxiliary isolation liquid or buffer in this structure cannot effectively collect leakage for flammable and explosive process gas conditions. Utility Model Content

[0004] In order to overcome at least one of the defects in the above prior art, the utility model provides a double-end face sealing device for a screw compressor, which has stable sealing performance and long service life, and can effectively seal in flammable and explosive working conditions.

[0005] The utility model provides a double-end face sealing device for a screw compressor, comprising a shaft sleeve and a sealing seat sleeved on the outside of the shaft sleeve for axial connection with the shell of the compressor, wherein the outer wall of the shaft sleeve located at one end in the shell is provided with a dynamic ring seat, a wet main seal is arranged between a first mounting groove of the sealing seat near one end of the shell and the dynamic ring seat, and a dry gas sealing component is arranged between the other end of the sealing seat and the other end of the shaft sleeve; a second mounting groove is arranged on the inner side of the sealing seat away from one end of the shell, the dry gas sealing component is accommodated in the second mounting groove, an air inlet and an air outlet respectively communicated with the second mounting groove are arranged on the sealing seat, a throttling component axially located between the first mounting groove and the second mounting groove is arranged between the inner wall of the sealing seat and the outer wall of the shaft sleeve; a flushing sleeve sleeved on the outer side of the main seal is connected to one end of the sealing seat located in the shell, an oil inlet hole and an oil outlet hole are arranged on the flushing sleeve, and a lip seal for preventing screw cavity oil from reversely entering the flushing sleeve is arranged between the inner wall of the flushing sleeve away from one end of the sealing seat and the outer wall of the shaft sleeve.

[0006] Compared with the prior art, the double end face sealing device for a screw compressor of the utility model has the following advantages:

[0007] 1. The double-end face sealing device structure for the screw compressor of the utility model has more stable sealing performance and longer service life compared with the traditional packing seal or single multi-pass lip seal structure;

[0008] 2. In this structure, the primary seal adopts a wet main seal, and the secondary seal adopts a dry gas seal, which can well cope with the working conditions where the process gas is flammable and explosive; in addition, the sealing chamber between the primary seal and the secondary seal is separated by a throttling component, which effectively prevents the medium from entering the dry gas end sealing chamber after the wet main seal leaks;

[0009] 3. More importantly, in this sealing structure, the oil required for the operation of the compressor itself is used to flush and cool the sealing surface of the wet main sealing structure, taking away the friction heat in time to ensure stable and reliable sealing performance;

[0010] 4. A lip seal is arranged between the inner wall of the flushing sleeve away from the sealing seat and the outer wall of the shaft sleeve to prevent the screw running oil in the shell from entering the flushing sleeve in reverse, that is, the lip of the lip seal faces the working chamber of the screw compressor. This design can effectively prevent the process gas compressed by the screw compressor and the working oil from entering the chamber where the wet main seal is located from the working chamber, and the pressure design requirement of the flushing oil is higher than the working chamber pressure of the compressor. The flushing oil side is on the back of the lip seal. The back of the lip seal is under pressure and theoretically has no sealing effect on the flushing oil. In addition, the flushing oil rushes into the screw chamber through the oil outlet hole to lubricate the screw and dissipate heat from the screw.

[0011] As an improvement, an annular groove is provided on the outer wall of the flushing sleeve near one end of the sealing seat, and a plurality of oil inlet holes distributed circumferentially and radially penetrating therethrough are provided at the bottom of the annular groove, each of the oil inlet holes corresponds to the sealing surface of the wet main seal, and an oil inlet channel connected to the annular groove is provided on the shell, and the oil outlet hole is connected to the screw chamber of the compressor.

[0012] Further improvement, a positioning retaining ring is provided on the inner wall of the shell, and the end of the flushing sleeve away from the sealing seat is close to the positioning retaining ring; a positioning boss is provided on the outer peripheral wall of the flushing sleeve, and the positioning boss is sealed with the inner wall of the shell to form an oil outlet buffer cavity between the inner wall of the shell and the positioning retaining ring, the flushing sleeve and the positioning boss; a waist-shaped hole extending in the circumferential direction is provided on the side wall of the flushing sleeve to form the oil outlet hole, and the oil outlet hole is connected to the oil outlet buffer cavity, and an oil return notch is provided on the side wall of the flushing sleeve near one end of the positioning retaining ring.

[0013] Furthermore, the throttling assembly includes a throttling ring connected to the bottom of the second mounting groove and located at the radial inner end, and a first throttling groove is arranged on the inner wall of the throttling ring; a second throttling groove is arranged on the outer wall of the sleeve near the first throttling groove.

[0014] As a further improvement, the sealing seat is provided with a collecting channel for connecting the first mounting groove and the air outlet.

[0015] Furthermore, the dry gas seal assembly includes a secondary dynamic ring and a secondary static ring, the outer part of the sleeve located in the second mounting groove is sleeved with a fixed sleeve, and the secondary dynamic ring is sleeved and fixed on the fixed sleeve; the sealing seat is connected to a positioning seat at one end away from the shell, and the positioning seat is provided with a static ring seat extending axially to the second mounting groove, the secondary static ring is mounted on the static ring seat, and a dry seal grinding surface that can rotate relative to each other in the circumferential direction is formed between the secondary static ring and the secondary dynamic ring.

[0016] As a further improvement, a plurality of spiral grooves are provided on the end surface where the auxiliary dynamic ring abuts against the auxiliary static ring, and the rotation direction of each of the spiral grooves is consistent with the rotation direction of the compressor main shaft.

[0017] As a further improvement, an annular stationary ring groove is provided on the stationary ring seat, one end of the secondary stationary ring is fitted in the stationary ring groove, and a retaining ring is provided between the stationary ring groove and the tail end of the secondary stationary ring, and an elastic compensation piece is provided between the end of the retaining ring away from the secondary stationary ring and the bottom of the stationary ring groove.

[0018] Other improved features and advantages of the utility model will be described in the subsequent specific embodiments, and partly become apparent from the description, or understood by implementing the utility model. The purpose and other advantages of the utility model can be achieved and obtained through the structures specifically pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a three-dimensional diagram of a double end face sealing device for a screw compressor of the utility model;

[0020] Figure 2 It is a front view of the double end face sealing device for the screw compressor of the utility model;

[0021] Figure 3 for Figure 2 Middle AA section view;

[0022] Figure 4 for Figure 2 Middle BB section view;

[0023] Figure 5 It is a structural schematic diagram of the flushing sleeve in the utility model;

[0024] Figure 6 for Figure 3 The structure diagram is enlarged at the X in the middle;

[0025] Figure 7 for Figure 4 The structure diagram at Y in the middle is enlarged;

[0026] Figure 8 for Figure 3 The structure diagram at Z is enlarged;

[0027] Fig. 9 It is a structural schematic diagram of the auxiliary dynamic ring in the utility model.

[0028] Description of reference numerals:

[0029] 1. Shaft sleeve; 2. Sealing seat; 3. Moving ring seat; 4. First mounting groove; 5. Second mounting groove; 6. Air inlet; 7. Air outlet; 8. Flushing sleeve; 9. Oil inlet hole; 10. Oil outlet hole; 11. Lip seal; 12. Annular groove; 13. Positioning retaining ring; 14. Positioning boss; 15. Oil outlet buffer chamber; 16. Oil return notch; 17. Throttle ring; 18. First throttle groove; 19. Second throttle groove; 20. Collecting channel; 21. Auxiliary moving ring; 22. Auxiliary static ring; 23. Fixed sleeve; 24. Positioning seat; 25. Static ring seat; 26. Spiral groove; 27. Static ring groove; 28. Retaining ring; 29. ​​Housing; 30. Active ring; 31. Main static ring; 32. Oil inlet channel; 33. Auxiliary exhaust hole. DETAILED DESCRIPTION

[0030] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0031] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "fixed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0032] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] See also Figures 1 to 8 As shown, an embodiment of the present application discloses a double-end face sealing device for a screw compressor, which includes a sleeve 1 mounted on the outside of the compressor main shaft, the sleeve 1 is drivingly connected to the main shaft, that is, the sleeve 1 rotates synchronously with the main shaft, a sealing ring is arranged between the inner wall of one end of the sleeve 1 and the main shaft, and the other end of the sleeve 1 is drivingly connected to the main shaft through a plurality of circumferentially distributed set screws.

[0034] A sealing seat 2 for axial connection with the compressor housing 29 is sleeved on the outside of the shaft sleeve 1, a dynamic ring seat 3 is arranged on the outer wall of the shaft sleeve 1 at one end inside the housing 29, a first mounting groove 4 is provided on the inner side of the sealing seat 2 near one end of the housing 29, a concave dynamic ring groove is provided on the dynamic ring seat 3 near one end of the sealing seat 2, and a wet main seal is arranged between the dynamic ring groove and the first mounting groove 4; specifically, the wet main seal comprises an active ring 30 and a main static ring 31, wherein one end of the active ring 30 is sealingly fitted in the dynamic ring groove, and one end of the main static ring 31 is along the It is axially slidably mounted in the first mounting groove 4, and the other end of the main static ring 31 is circumferentially rotatably abutted against the other end of the active ring 30 to form a main sealing grinding surface to play a main sealing role. In addition, in this structure, an elastic compensation part is also arranged between the main static ring 31 and the bottom of the first mounting groove 4, which is mainly used to compensate for the wear of the main sealing grinding surface. When the sealing grinding surface is worn, the main static ring 31 is always tightly fitted on the end face of the active ring 30 under the action of the elastic compensation part, so as to ensure stable and reliable sealing performance.

[0035] In addition, a dry gas sealing assembly is arranged between the other end of the sealing seat 2 and the other end of the sleeve 1; a second mounting groove 5 is provided on the inner side of the sealing seat 2 away from the end of the shell 29, and the dry gas sealing assembly is accommodated in the second mounting groove 5. The sealing seat 2 is provided with an air inlet 6 and an air outlet 7 which are respectively connected to the second mounting groove 5. In this structure, the air inlet 6 and the air outlet 7 are mainly arranged to provide special gas to the dry gas sealing assembly to ensure that a stable sealing air film is formed between the sealing grinding surfaces of the dry gas sealing assembly.

[0036] On the other hand, a throttling assembly is provided between the inner wall of the sealing seat 2 and the outer wall of the sleeve 1 and is axially located between the first mounting groove 4 and the second mounting groove 5. The throttling assembly here divides the sealing chamber of the entire mechanical seal into two independent sealing chambers to prevent the medium from entering the dry gas end sealing chamber after the wet main seal leaks.

[0037] In addition, at the wet seal end, a flushing sleeve 8 sleeved on the outside of the wet main seal is connected to the end of the seal seat 2 located in the housing 29, and the flushing sleeve 8 is provided with an oil inlet 9 and an oil outlet 10, wherein the oil inlet is connected to the oil inlet of the compressor, and the oil outlet 10 is directly connected to the screw cavity, and the operating oil of the compressor itself is used to flush and cool the wet main seal, thereby ensuring the service life and sealing performance of the wet main seal; and a lip seal 11 is provided between the inner wall of the flushing sleeve 8 away from the end of the seal seat 2 and the outer wall of the shaft sleeve 1 to prevent the screw operating oil in the housing 29 from reversely entering the flushing sleeve 8. In this structure, the lip of the lip seal 11 faces the working cavity of the screw compressor. This design can effectively prevent the process gas and working oil compressed by the screw compressor from entering the cavity where the wet main seal is located from the working cavity, and the pressure design requirement of the flushing oil is higher than the working cavity pressure of the compressor. The flushing oil side is on the back of the lip seal 11, and the back of the lip seal 11 is under pressure, which theoretically has no sealing effect on the flushing oil. On the right side of the flushing sleeve 8 close to the lip seal 11, an oil outlet 10 is designed to allow the flushing oil to enter the screw cavity to lubricate the screw and dissipate the heat of the screw. On the other hand, the design of the lip seal 11 allows the outer side of the main sealing end face to be filled with oil more fully, so that the sealing surface can operate in the working condition with liquid film for a long time, thereby increasing the service life of the seal.

[0038] More specifically, in this embodiment, see the attached Figure 5 and 6 An annular groove 12 is provided on the outer wall of the flushing sleeve 8 near one end of the sealing seat 2, and a plurality of oil inlet holes 9 distributed circumferentially and radially penetrating are provided at the bottom of the annular groove 12, each oil inlet hole 9 corresponds to the sealing surface of the wet main seal, and an oil inlet channel 32 connected to the annular groove 12 is provided on the shell 29, and the oil outlet hole 10 is connected to the screw cavity of the compressor. The multi-point distributed flushing inlet design effectively improves the flushing and cooling effect of the sealing grinding surface of the wet main seal.

[0039] In addition, in the above structure, see the attached Figure 6 It can be seen that a positioning retaining ring 13 is provided on the inner wall of the housing 29, and the end of the flushing sleeve 8 away from the sealing seat 2 is close to the positioning retaining ring 13; and a positioning boss 14 is provided on the outer peripheral wall of the flushing sleeve 8, and the positioning boss 14 is sealed with the inner wall of the housing 29, so that an oil outlet buffer chamber 15 is formed between the inner wall of the housing 29 and the positioning retaining ring 13, the flushing sleeve 8, and the positioning boss 14, that is, the flushing oil will not directly and quickly return to the screw cavity, but will first enter the oil outlet buffer chamber 15 for buffering, and the side of the flushing sleeve 8 A waist-shaped hole extending in the circumferential direction is opened on the wall to form an oil outlet hole 10, and the oil outlet hole 10 is connected to the oil outlet buffer chamber 15. An oil return notch 16 is opened on the side wall of the flushing sleeve 8 near the end of the positioning baffle ring 13. In this structure, the design of the waist-shaped oil outlet hole 10, the oil outlet buffer chamber 15 and the oil return notch 16 allows the oil to maintain a suitable flow rate and flow rate to flow back to the screw chamber, while meeting the flushing and cooling of the wet main seal, better ensuring the normal operation of the screw, and will not cause abnormal operation of the screw due to abnormal oil return.

[0040] In this embodiment, preferably, the throttling assembly includes a throttling ring 17 connected to the bottom of the second mounting groove 5 and located at the radial inner end, and a first throttling groove 18 is arranged on the inner wall of the throttling ring 17; a second throttling groove 19 is arranged on the outer wall of the sleeve 1 near the first throttling groove 18, and two groups of throttling groove structures are arranged axially, which effectively improves the throttling effect and better prevents oil from entering the dry gas sealing chamber after the wet main seal fails.

[0041] In the present embodiment, another important structure is that a collecting channel 20 for connecting the first mounting groove 4 and the air outlet 7 is provided on the sealing seat 2. Therefore, even if a slight leakage occurs at the wet main seal, the oil leaked into the corresponding chamber will enter the air outlet 7 through the collecting channel 20, and then be processed at the air outlet 7 by connecting to a dedicated oil-gas separation device.

[0042] See attached Figure 8 and 9 The dry gas seal assembly includes a secondary moving ring 21 and a secondary static ring 22. The shaft sleeve 1 is provided with a fixed sleeve 23 on the outside of the inner part of the second mounting groove 5. The secondary moving ring 21 is fixed on the fixed sleeve 23. The end of the seal seat 2 away from the housing 29 is connected with a positioning seat 24. The positioning seat 24 is provided with a static ring seat 25 extending axially to the second mounting groove 5. The secondary static ring 22 is mounted on the static ring seat 25, and a dry seal grinding surface that can rotate relatively in the circumferential direction is formed between the secondary static ring 22 and the secondary moving ring 21. Among them, a plurality of spiral grooves 26 are provided on the end surface where the secondary moving ring 21 abuts against the secondary static ring 22, and the rotation direction of each spiral groove 26 is consistent with the rotation direction of the compressor main shaft, so that a stable gas film is formed between the end surfaces of the secondary moving ring 21 and the secondary static ring 22.

[0043] See the attached Figure 8 An annular stationary ring groove 27 is provided on the stationary ring seat 25, one end of the auxiliary stationary ring 22 is slidably mounted in the stationary ring groove 27 along the axial direction, and a retaining ring 28 is provided between the stationary ring groove 27 and the tail end of the auxiliary stationary ring 22, and an elastic compensating member is provided between the end of the retaining ring 28 away from the auxiliary stationary ring 22 and the bottom of the stationary ring groove 27. The elastic compensating member acts on the auxiliary stationary ring 22 through the retaining ring 28, which can make the PV value between the auxiliary stationary ring 22 and the auxiliary dynamic ring 21 more stable, thereby ensuring stable and reliable sealing performance.

[0044] In addition, see Appendix Figure 6 and 8 The elastic compensator at the dry gas seal assembly has the same structure as the elastic compensator at the wet main seal, both of which include multiple cylindrical springs evenly distributed along the circumference, and corresponding spring holes are opened at the bottom of the first mounting seat or the static ring groove 27. One end of each spring is positioned in the corresponding spring hole, and the other end is abutted against the tail end of the main static ring 31 or the end of the retaining ring 28 away from the secondary static ring 22. The spring hole is set to better ensure the stability of the spring expansion and contraction. The above two elastic compensators are both set at the tail end of the static ring, that is, the static mechanical seal design. Even if the main shaft runs or the shaft diameter is relatively large, it can still effectively compensate the sealing surface and increase the service life of the mechanical seal.

[0045] In addition, see Appendix Figure 3 It can be seen that an auxiliary exhaust hole 33 is also provided at the upper end of the sealing seat 2. If the inflammable and explosive gas leaks, if it is liquefied in the low-pressure area, it can be collected through the outlet 7; if it is not liquefied in the low-pressure area, it is collected through the auxiliary exhaust hole 33. This can better ensure that the inflammable and explosive gas will not leak into the atmosphere and cause harm, and the safety is high.

[0046] In the description of the present application, the description with reference to the terms "present embodiment", "some embodiments", etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradicting each other.

[0047] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A double end face sealing device for a screw compressor, characterized in that: The invention comprises a shaft sleeve (1) and a sealing seat (2) sleeved on the outside of the shaft sleeve (1) for axial connection with a housing (29) of a compressor, wherein the outer wall of the shaft sleeve (1) at one end inside the housing (29) is provided with a dynamic ring seat (3), a wet main seal is arranged between a first mounting groove (4) at one end of the sealing seat (2) close to the housing (29) and the dynamic ring seat (3), and a dry gas sealing assembly is arranged between the other end of the sealing seat (2) and the other end of the shaft sleeve (1); a second mounting groove (5) is arranged on the inner side of the end of the sealing seat (2) away from the housing (29), and the dry gas sealing assembly is accommodated in the second mounting groove (5), and the sealing seat (2) is provided with a plurality of mounting grooves (4) on the inner side of the housing (29). An air inlet (6) and an air outlet (7) are provided on the seal seat (2) and are connected to the second mounting groove (5) respectively; a throttling assembly is provided between the inner wall of the seal seat (2) and the outer wall of the shaft sleeve (1) and is axially located between the first mounting groove (4) and the second mounting groove (5); one end of the seal seat (2) located in the housing (29) is connected to a flushing sleeve (8) sleeved on the outside of the wet main seal; the flushing sleeve (8) is provided with an oil inlet hole (9) and an oil outlet hole (10); a lip seal (11) is provided between the inner wall of the flushing sleeve (8) at one end away from the seal seat (2) and the outer wall of the shaft sleeve (1) for preventing the oil in the screw chamber from reversely entering the flushing sleeve (8).

2. The double end face sealing device for a screw compressor according to claim 1, characterized in that: An annular groove (12) is provided on the outer wall of the flushing sleeve (8) near one end of the sealing seat (2), and a plurality of oil inlet holes (9) distributed along the circumference and radially penetrating the annular groove (12) are provided at the bottom of the annular groove (12), and each of the oil inlet holes (9) corresponds to the sealing surface of the wet main seal. An oil inlet channel (32) connected to the annular groove (12) is provided on the housing (29), and the oil outlet hole (10) is connected to the screw chamber of the compressor.

3. The double end face sealing device for a screw compressor according to claim 1 or 2, characterized in that: A positioning retaining ring (13) is arranged on the inner wall of the shell (29), and one end of the flushing sleeve (8) away from the sealing seat (2) is close to the positioning retaining ring (13); a positioning boss (14) is arranged on the outer peripheral wall of the flushing sleeve (8), and the positioning boss (14) is sealed with the inner wall of the shell (29) so that an oil outlet buffer cavity (15) is formed between the inner wall of the shell (29) and the positioning retaining ring (13), the flushing sleeve (8) and the positioning boss (14); a waist-shaped hole extending in the circumferential direction is opened on the side wall of the flushing sleeve (8) to form the oil outlet hole (10), and the oil outlet hole (10) is connected to the oil outlet buffer cavity (15), and an oil return notch (16) is opened on the side wall of the flushing sleeve (8) near the end of the positioning retaining ring (13).

4. The double end face sealing device for a screw compressor according to claim 1, characterized in that: The throttling assembly comprises a throttling ring (17) connected to the bottom of the second mounting groove (5) and located at the radial inner end, and a first throttling groove (18) is arranged on the inner wall of the throttling ring (17); and a second throttling groove (19) is arranged on the outer wall of the shaft sleeve (1) near the first throttling groove (18).

5. The double end face sealing device for a screw compressor according to claim 1 or 4, characterized in that: The sealing seat (2) is provided with a collecting channel (20) for connecting the first mounting groove (4) and the air outlet (7).

6. The double end face sealing device for a screw compressor according to claim 1, characterized in that: The dry gas seal assembly comprises a secondary dynamic ring (21) and a secondary static ring (22); the shaft sleeve (1) is sleeved with a fixed sleeve (23) on the outside of the inner part of the second mounting groove (5); the secondary dynamic ring (21) is sleeved and fixed on the fixed sleeve (23); the seal seat (2) is connected to a positioning seat (24) at one end away from the housing (29); the positioning seat (24) is provided with a static ring seat (25) extending axially to the second mounting groove (5); the secondary static ring (22) is mounted on the static ring seat (25), and a dry seal grinding surface that can rotate relatively in the circumferential direction is formed between the secondary static ring (22) and the secondary dynamic ring (21).

7. The double end face sealing device for a screw compressor according to claim 6, characterized in that: A plurality of spiral grooves (26) are provided on the end surface where the auxiliary dynamic ring (21) abuts against the auxiliary static ring (22), and the rotation direction of each spiral groove (26) is consistent with the rotation direction of the compressor main shaft.

8. The double end face sealing device for a screw compressor according to claim 6 or 7, characterized in that: An annular stationary ring groove (27) is provided on the stationary ring seat (25), one end of the auxiliary stationary ring (22) is mounted in the stationary ring groove (27), a retaining ring (28) is provided between the stationary ring groove (27) and the tail end of the auxiliary stationary ring (22), and an elastic compensation piece is provided between the end of the retaining ring (28) away from the auxiliary stationary ring (22) and the bottom of the stationary ring groove (27).

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