A sealing structure applied to a dry-type oil-free double-screw compressor

Abstract

The utility model relates to a compressor sealing technical field, concretely relates to a sealing structure for being applied to dry type oil -free double screw compressor, including sealed cavity, rotating part, prelacing labyrinth seal, carbon ring seal and rotating shaft seal. Rotating part sets up in sealed cavity inside. From sealed cavity close to compressor compression cavity one side, prelacing labyrinth seal, carbon ring seal and rotating shaft seal are in sealed cavity inside in proper order and are coaxially covered and set up rotating part outside. The balance port, the vent, the isolated gas inlet and the lubricating oil inlet are arranged on the sealed cavity. The structure adds prelacing labyrinth seal and rotating shaft seal on the basis of carbon ring seal, forms combined sealing, and its combination different sealing characteristics can realize efficient, excellent sealing effect.

Description

Technical Field

[0001] This utility model relates to the field of compressor sealing technology, specifically to a sealing structure applied to a dry oil-free twin-screw compressor. Background Technology

[0002] The compression process of a dry-type oil-free twin-screw compressor is non-contact compression. Its core operating system consists of male and female rotors, a synchronous gear set, and bearings. The male and female rotors do not directly contact each other during compression; they are driven separately by the synchronous gear set, composed of a driving wheel and a driven wheel, achieving precise meshing. Simultaneously, the male and female rotors are supported and positioned by bearings, ensuring coaxiality and stability during operation. Because the system includes moving parts such as bearings and synchronous gears, lubricating oil needs to be continuously supplied during compressor operation to reduce frictional losses and extend service life. Therefore, a sealing structure must be installed between the compression chamber and the bearing / gear chamber. This sealing structure must provide bidirectional isolation, preventing the compressed medium from leaking into the bearing / gear chamber and preventing the medium from mixing and contaminating the lubricating oil, while also preventing lubricating oil or impurities in the bearing / gear chamber from entering the compression chamber, ensuring the purity of the compressed medium. Its performance directly determines the compressor's operational reliability and applicable scenarios.

[0003] Currently, the industry mainly adopts four types of sealing structures to meet the sealing requirements of dry oil-free twin-screw compressors.

[0004] The first type is the rotary shaft seal, also known as a lip seal. It forms a seal by tightly fitting one or more lips against the surface of the rotating shaft. The lips can self-deform under hydraulic pressure to ensure a proper fit with the sealing surface, and they also have a certain degree of self-compensation capability after wear occurs. This structure is simple in design and low in manufacturing cost. However, because the lip and the rotating shaft are in contact, friction and wear are inevitable during operation. Long-term use can easily lead to seal failure, and it is not suitable for dry friction conditions. Poor lubrication will significantly shorten its service life.

[0005] The second type is mechanical seals, which are also contact seals. The core components include a rotating ring and a stationary ring. The rotating ring is made of graphite, and the stationary ring is made of silicon carbide. The rotating ring and spring assembly are fixed to the shaft and rotate synchronously with it, while the stationary ring is locked to the housing. Medium isolation is achieved through continuous friction between the rotating and stationary rings. After the rotating ring wears down, the preload of the spring maintains contact with the stationary ring, ensuring continuous sealing. This structure provides relatively good sealing, but the contact friction between the rotating and stationary rings generates a large amount of heat, requiring coolant to be circulated through the sealing area for cooling. Furthermore, it is not suitable for high-speed, high-temperature operating scenarios, limiting its applicability.

[0006] The third type is the labyrinth seal, which is a non-contact seal. This structure can achieve a good sealing effect when the compressor is running at high speed and stable conditions. However, due to the inherent gap between the rotating and stationary parts, the leakage problem will be significantly aggravated under unstable operating conditions such as compressor start-up, acceleration, deceleration, and shutdown, making it difficult to meet the application scenarios with strict requirements for leakage control.

[0007] The fourth type is the carbon ring seal, which is also a non-contact seal. This structure can adapt to high speed and high temperature conditions, but due to the inherent gap between the graphite sealing ring and the bushing, leakage problems are still prone to occur during compressor start-up and shutdown and unstable speed changes, making it difficult to simultaneously meet the dual requirements of high adaptability to operating conditions and low leakage.

[0008] In summary, the sealing structures currently used in dry oil-free twin-screw compressors all have significant technical shortcomings. Contact-type rotary shaft seals and mechanical seals are either limited by dry friction life or by high-speed, high-temperature operating conditions. Non-contact labyrinth seals and carbon ring seals, on the other hand, suffer from significant leakage problems due to inherent gaps, especially under unstable operating conditions. These issues mean that existing sealing structures cannot fully meet the sealing requirements of dry oil-free twin-screw compressors under different operating conditions, necessitating a sealing structure design that balances adaptability to operating conditions and low leakage performance. Utility Model Content

[0009] To overcome the shortcomings of existing technologies, this application provides a sealing structure for use in dry-type oil-free twin-screw compressors. This structure, based on a carbon ring seal, adds a pre-positioned labyrinth seal and a rotary shaft seal to form a combined seal. By combining the characteristics of different seals, it achieves efficient and excellent sealing performance.

[0010] To achieve the above objectives, this utility model provides a sealing structure for use in dry oil-free twin-screw compressors.

[0011] The sealing structure used in a dry, oil-free twin-screw compressor includes a sealing cavity, a rotating component, a pre-labyrinth seal, a carbon ring seal, and a rotating shaft seal. The rotating component is located inside the sealing cavity. The pre-labyrinth seal, carbon ring seal, and rotating shaft seal are sequentially arranged inside the sealing cavity, starting from the side closest to the compressor's compression chamber, and coaxially fitted around the rotating component. The sealing cavity is equipped with a balance port, a vent port, an isolation gas inlet, and a lubricating oil inlet. The balance port is located on the side of the carbon ring seal closest to the pre-labyrinth seal and communicates with the interior of the sealing cavity. The isolation gas inlet is located in the axial center of the carbon ring seal and communicates with the interior of the sealing cavity. The vent port is located on the side of the carbon ring seal closest to the rotating shaft seal and communicates with the interior of the sealing cavity. The lubricating oil inlet is located on the side of the rotating shaft seal furthest from the carbon ring seal and communicates with the interior of the sealing cavity.

[0012] Preferably, the carbon ring seal includes multiple carbon rings, which are sequentially arranged in the annular groove of the sealing cavity along the axial direction of the rotating component. Preferably, the carbon ring seal includes at least seven carbon rings.

[0013] Preferably, the inner wall of the annular groove of the sealing cavity is provided with an annular limiting boss, and adjacent carbon rings are separated by the limiting boss, and the two end faces of the carbon rings are respectively in contact with the two sides of the limiting boss.

[0014] Preferably, the gap between the carbon ring of the carbon ring seal and the outer surface of the rotating part is 0.01 to 0.04 mm.

[0015] Preferably, the rotary shaft seal has a lip, which is positioned towards the carbon ring seal side and is in contact with the outer surface of the rotating component.

[0016] Preferably, the front labyrinth seal includes several annular sealing teeth, which are arranged sequentially along the axial direction of the rotating component, and a flow-blocking gap and an expansion cavity are formed between adjacent annular sealing teeth.

[0017] Preferably, the tip of the annular sealing tooth of the front labyrinth seal is rounded, with a radius of 0.1 to 0.2 mm.

[0018] Preferably, the inner wall of the sealing cavity is provided with stepped positioning grooves, and the front labyrinth seal, carbon ring seal and rotary shaft seal are respectively embedded in the corresponding positioning grooves and fixedly connected to the sealing cavity by bolts.

[0019] Preferably, the outer surface of the rotating component is provided with a wear-resistant coating at the position corresponding to the carbon ring seal, and the thickness of the wear-resistant coating is 0.05 to 0.1 mm.

[0020] Preferably, an annular sealing gasket is provided on the contact surface between the front labyrinth seal and the sealing cavity. The inner diameter of the annular sealing gasket is clearance-fitted with the outer diameter of the rotating part, and the cross-section of the annular sealing gasket is U-shaped and opens towards the compression cavity.

[0021] Compared with the prior art, the beneficial effects of this application are as follows: Firstly, the sealing structure applied to dry-type oil-free twin-screw compressors integrates the advantages of a front-mounted labyrinth seal, carbon ring seal, and rotary shaft seal, overcoming the inherent disadvantages of a single seal. This combined sealing structure avoids the problem of labyrinth seals failing to provide a complete seal, solves the shortcomings of carbon ring seals in handling frequent start-stop cycles, and overcomes the defect of rotary shaft seals being unsuitable for high temperatures and high speeds. This allows each seal to function properly within the combined structure, creating a synergistic sealing effect.

[0022] Secondly, this combined sealing structure is adaptable to various operating conditions of dry-type oil-free twin-screw compressors, capable of handling high-speed operation scenarios. It achieves effective sealing by leveraging the throttling effect of the front labyrinth seal and the stable gap of the carbon ring seal. It can also adapt to high-temperature environments of compressed media, ensuring operational reliability through the high-temperature resistance of the carbon ring seal. Furthermore, it can handle frequent start-stop conditions, reducing leakage risks during start-stop phases by utilizing the characteristic of the carbon ring to contact rotating parts by gravity when stationary and to form a stable gap through centrifugal force during operation.

[0023] Furthermore, this structure completely solves the leakage problem of the original single seal. This combined sealing structure combines the auxiliary sealing of the isolation gas, the pressure regulation of the balance port, and the final sealing effect of the rotary shaft seal, ensuring that the compressed medium does not leak into the bearing gear cavity, while preventing lubricating oil or impurities from contaminating the compressed medium, ultimately achieving the optimal sealing effect. Attached Figure Description

[0024] This application can be better understood by describing its embodiments in conjunction with the accompanying drawings, in which: Figure 1 This is a schematic diagram of a sealing structure applied to a dry oil-free twin-screw compressor according to this application; Figure 2 For example Figure 1 The illustrated embodiment is a schematic diagram of the working state of the carbon ring seal when the medium is under positive pressure; Figure 3 For example Figure 1 The illustrated embodiment is a schematic diagram of the working state of the carbon ring seal when the medium is under negative pressure.

[0025] Explanation of icon numbers: 1. Sealed cavity; 2. Rotating component; 3. Pre-labyrinth seal; 4. Carbon ring seal; 5. Rotary shaft seal; 6. Balance port; 7. Vent port; 8. Isolation gas inlet; 9. Lubricating oil inlet. Detailed Implementation

[0026] Unless otherwise defined, the technical or scientific terms used in this specification and claims shall have the ordinary meaning as understood by one of ordinary skill in the art to which this utility model pertains.

[0027] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0028] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0029] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. They can refer to a mechanical connection or an electrical connection. They can refer to a direct connection or an indirect connection through an intermediate medium, or a connection within two components. For those skilled in the art, the specific meaning of the above terms in this utility model can be understood through the specific circumstances.

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0031] This utility model provides a method such as Figures 1 to 3 The diagram shows a sealing structure applied to a dry, oil-free twin-screw compressor.

[0032] The sealing structure applied to a dry, oil-free twin-screw compressor includes a sealing cavity 1, a rotating component 2, a pre-labyrinth seal 3, a carbon ring seal 4, and a rotating shaft seal 5. The rotating component 2 is disposed inside the sealing cavity 1. The rotating component 2 can be a rotor shaft or a shaft sleeve. The pre-labyrinth seal 3, the carbon ring seal 4, and the rotating shaft seal 5 are sequentially disposed inside the sealing cavity 1, starting from the side of the sealing cavity 1 closest to the compressor compression chamber, and are coaxially sleeved outside the rotating component 2.

[0033] This combined sealing structure uses a sealing cavity 1 as the basic carrier, with a rotating component 2 disposed within it. A pre-labyrinth seal 3, a carbon ring seal 4, and a rotating shaft seal 5 are sequentially arranged inside the sealing cavity 1 from near to far from the compression cavity, thus forming a layered interception sealing path. This layout forces the compressed medium to pass through multiple seals sequentially, significantly improving leakage prevention compared to a single seal and reducing leakage risk at the structural source.

[0034] In some embodiments, the inner wall of the sealing cavity 1 is provided with stepped positioning grooves. The front labyrinth seal 3, carbon ring seal 4, and rotary shaft seal 5 are respectively embedded in the corresponding positioning grooves and fixedly connected to the sealing cavity 1 by bolts. This connection method can precisely limit the front labyrinth seal 3, carbon ring seal 4, and rotary shaft seal 5 to their corresponding assembly positions. Even if the compressor vibrates during operation, the sealing components will not undergo axial displacement or radial offset, ensuring stable sealing gaps and fit, avoiding seal failure due to component loosening, and extending the service life of the overall structure.

[0035] The pre-labyrinth seal 3 may include several annular sealing teeth arranged sequentially along the axial direction of the rotating component 2, with intercepting gaps and expansion cavities formed between adjacent annular sealing teeth. During operation, when the compressed medium passes through the gaps, it forms eddies and generates a throttling effect, initially reducing the medium pressure and permeability. Preferably, the tips of the annular sealing teeth of the pre-labyrinth seal 3 are rounded, with a radius of 0.1–0.2 mm. The rounded corner treatment can reduce the wear of the teeth caused by medium impact and extend the service life of the sealing teeth.

[0036] In some embodiments, an annular sealing gasket is provided on the contact surface between the pre-labyrinth seal 3 and the sealing cavity 1. The inner diameter of the annular sealing gasket is clearance-fitted with the outer diameter of the rotating component 2, and the cross-section of the annular sealing gasket is U-shaped and opens towards the compression cavity. The U-shaped annular sealing gasket can further prevent the initial medium from leaking from the gap between the seal and the cavity, enhancing the pre-sealing effect, and is especially suitable for high-speed operation scenarios of the compressor.

[0037] The gap between the carbon ring of the carbon ring seal 4 and the outer surface of the rotating part 2 can be 0.01–0.04 mm. When the compressor is stationary, the carbon ring contacts the outer surface of the rotating part 2 due to gravity, preventing excessive gaps that could lead to leakage during start-up and shutdown. During operation, the carbon ring forms a stable gap with the rotating part 2 under centrifugal force, reducing frictional losses.

[0038] The carbon ring seal 4 may include multiple carbon rings, which are sequentially arranged in the annular groove of the sealing cavity 1 along the axial direction of the rotating member 2. The axial arrangement of multiple carbon rings can throttle the medium multiple times, gradually reducing the leakage. Preferably, the carbon ring seal 4 includes at least seven carbon rings.

[0039] The outer surface of the rotating part 2, corresponding to the position of the carbon ring seal 4, may be provided with a wear-resistant coating, the thickness of which is 0.05 to 0.1 mm.

[0040] The inner wall of the annular groove of the sealing cavity 1 may be provided with an annular limiting boss. Adjacent carbon rings are separated by the limiting boss, and the two end faces of the carbon rings respectively fit against the two sides of the limiting boss. The limiting boss of the annular groove in the sealing cavity 1 can be used to precisely separate adjacent carbon rings, prevent the carbon rings from stacking or shifting axially, ensure that the sealing gap of each carbon ring is uniform, ensure that multiple carbon rings work together, and effectively cope with frequent start-stop conditions.

[0041] Preferably, the rotary shaft seal 5 has a lip, which faces the carbon ring seal 4 and is in contact with the outer surface of the rotating component 2. During operation, the lubricating oil introduced by the lubricating oil inlet 9 first lubricates the bearings and gears, and then flows to the lip of the rotary shaft seal 5, reducing friction and wear between the lip and the rotating component 2. After the lip wears, it automatically compensates through its own elasticity, always maintaining a tight fit, forming a final sealing barrier to prevent the leakage of a small amount of residual medium after passing through the carbon ring seal 4, while preventing lubricating oil from re-entering the carbon ring area and contaminating the medium.

[0042] The sealing cavity 1 is provided with a balance port 6, a vent port 7, an isolation gas inlet 8, and a lubricating oil inlet 9. The balance port 6 is located on the side of the carbon ring seal 4 near the front labyrinth seal 3 and communicates with the inside of the sealing cavity 1. The isolation gas inlet 8 is located in the axial middle of the carbon ring seal 4 and communicates with the inside of the sealing cavity 1. The vent port 7 is located on the side of the carbon ring seal 4 near the rotating shaft seal 5 and communicates with the inside of the sealing cavity 1. The lubricating oil inlet 9 is located on the side of the rotating shaft seal 5 away from the carbon ring seal 4 and communicates with the inside of the sealing cavity 1.

[0043] In the embodiments described in this application, each opening on the sealing cavity 1 precisely matches the sealing assembly. The balance port 6 is located upstream of the carbon ring seal 4. When the medium is under positive pressure, it connects to the low-pressure side suction port of the compressor; when the medium is under negative pressure, it connects to the positive pressure medium on the exhaust side, effectively balancing the pressure difference on both sides of the carbon ring seal 4 and reducing the power of medium leakage. The isolation gas inlet 8 is located in the middle of the carbon ring seal 4. The pressurized isolation gas introduced flows bidirectionally along the axial direction of the rotating component 2, preventing the upstream medium from breaking through the carbon ring and flowing to the right into the lubricating oil space before finally being discharged to the atmosphere, preventing lubricating oil from contaminating the carbon ring. The vent port 7 promptly discharges the mixed gas downstream of the carbon ring seal 4, preventing pressure buildup from affecting the seal. The lubricating oil inlet 9 provides a channel for the rotary shaft seal 5 and the bearing to share lubrication, simplifying the structure while ensuring the stable operation of the rotary shaft seal 5.

[0044] Specifically, in the embodiments described in this application, during operation, when the compressed medium permeates outward, it first contacts the pre-labyrinth seal 3. Through the intercepting gap between the annular sealing teeth and the expansion cavity, a vortex throttling effect is formed, initially reducing the pressure. Simultaneously, the U-shaped annular sealing gasket prevents leakage of the medium from the gap between the seal and the cavity. The remaining medium continues to permeate into the carbon ring seal 4 area. At this time, the balance port 6 balances the pressure difference on both sides of the carbon ring by connecting the medium on the corresponding pressure side, reducing leakage force. When stationary, the carbon ring contacts the rotating component 2 by gravity; during operation, it forms a stable gap of 0.01–0.04 mm by centrifugal force. Combined with the bidirectional flow of pressurized gas introduced through the isolation gas inlet 8, this not only prevents the medium from breaking through multiple carbon rings but also prevents downstream lubricating oil contamination.

[0045] When the compressed medium is under positive pressure, if it is a normal positive pressure, the balance port 6 is closed. The medium after passing through the carbon filter merges with the isolation gas flowing to the left from the isolation gas inlet 8 and is discharged from the vent port 7. If it is a high-pressure positive pressure, such as Figure 2 As shown, the balance port 6 is connected to the low-pressure side intake port of the compressor. The medium, which still has a high pressure after passing through the first two carbon rings of the pre-labyrinth seal 3 and carbon ring seal 4, is led to the low-pressure side intake port through the balance port 6, which significantly reduces the pressure of the medium that continues to permeate to the right. The remaining medium merges with the isolation gas flowing to the left from the isolation gas inlet 8 and is discharged from the vent port 7, further improving the effect of the carbon ring seal 4.

[0046] When the compression medium is under negative pressure, such as Figure 3 As shown, the positive pressure medium from the compressor exhaust side is introduced through the balance port 6. A portion of the positive pressure medium flows to the left, counteracting the isolation gas that permeates into the compression chamber, thus preventing the isolation gas from the isolation gas inlet 8 from entering the compression chamber and contaminating the medium. The other portion of the positive pressure medium flows to the right, merging with the isolation gas flowing to the left from the isolation gas inlet 8, and is discharged from the vent port 7.

[0047] A small amount of residual medium that breaks through the carbon ring is intercepted by the lip of the rotating shaft seal 5. The lip is in close contact with the rotating part 2 and is lubricated by the lubricating oil introduced through the lubricating oil inlet 9. After wear, it can be elastically compensated. Finally, the trace amount of mixed gas that is not intercepted is discharged through the vent 7, realizing the complete isolation of the medium and the lubricating oil, and adapting to stable operation under multiple working conditions.

[0048] The embodiments involved in this application achieve complete isolation between the compression medium and the lubricating oil through multi-layer sealing cooperation, adaptive design for operating conditions, and precise pressure regulation. This ensures the purity of the compression medium and adapts to various operating conditions such as high speed, high and low pressure media, and frequent start-stop, significantly improving the operating stability and service life of the compressor.

[0049] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above are only specific embodiments of this utility model and are not intended to limit this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A sealing structure applied to a dry, oil-free twin-screw compressor, characterized in that, The device includes a sealed cavity, a rotating component, a pre-labyrinth seal, a carbon ring seal, and a rotating shaft seal. The rotating component is disposed inside the sealed cavity. The pre-labyrinth seal, carbon ring seal, and rotating shaft seal are sequentially disposed inside the sealed cavity, starting from the side of the sealed cavity closest to the compressor's compression chamber, and coaxially sleeved on the outside of the rotating component. The sealed cavity is provided with a balance port, a vent port, an isolation gas inlet, and a lubricating oil inlet. The balance port is located on the side of the carbon ring seal closest to the pre-labyrinth seal and communicates with the interior of the sealed cavity. The isolation gas inlet is located in the axial middle of the carbon ring seal and communicates with the interior of the sealed cavity. The vent port is located on the side of the carbon ring seal closest to the rotating shaft seal and communicates with the interior of the sealed cavity. The lubricating oil inlet is located on the side of the rotating shaft seal furthest from the carbon ring seal and communicates with the interior of the sealed cavity.

2. The sealing structure according to claim 1, characterized in that, The carbon ring seal comprises multiple carbon rings, which are sequentially arranged in the annular groove of the sealing cavity along the axial direction of the rotating component.

3. The sealing structure according to claim 2, characterized in that, The inner wall of the annular groove of the sealed cavity is provided with an annular limiting boss. Adjacent carbon rings are separated by the limiting boss, and the two end faces of the carbon rings are respectively attached to the two sides of the limiting boss.

4. The sealing structure according to claim 1, characterized in that, The gap between the carbon ring of the carbon ring seal and the outer surface of the rotating part is 0.01 to 0.04 mm.

5. The sealing structure according to claim 1, characterized in that, The rotating shaft seal has a lip, which is positioned towards the carbon ring seal side and is in contact with the outer surface of the rotating component.

6. The sealing structure according to claim 1, characterized in that, The pre-labyrinth seal includes several annular sealing teeth, which are arranged sequentially along the axial direction of the rotating component, and a flow-blocking gap and an expansion cavity are formed between adjacent annular sealing teeth.

7. The sealing structure according to claim 6, characterized in that, The tip of the annular sealing tooth of the pre-labyrinth seal is rounded, with a radius of 0.1 to 0.2 mm.

8. The sealing structure according to claim 1, characterized in that, The inner wall of the sealed cavity is provided with stepped positioning grooves. The front labyrinth seal, carbon ring seal and rotary shaft seal are respectively embedded in the corresponding positioning grooves and fixedly connected to the sealed cavity by bolts.

9. The sealing structure according to claim 1, characterized in that, The outer surface of the rotating component is provided with a wear-resistant coating at the position corresponding to the carbon ring seal, and the thickness of the wear-resistant coating is 0.05 to 0.1 mm.

10. The sealing structure according to claim 1, characterized in that, The contact surface between the front labyrinth seal and the sealing cavity is provided with an annular sealing gasket. The inner diameter of the annular sealing gasket is clearance-fitted with the outer diameter of the rotating component, and the cross-section of the annular sealing gasket is U-shaped and opens towards the compression cavity.

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