A well shut-in device for well logging

Abstract

The application discloses a well sealing device for well logging, and relates to the technical field of well logging wellhead safety, which comprises a sleeve fixed on the inner wall of the well logging, a fixed ring body fixed on the inner wall of the sleeve at the wellhead, a plurality of annularly distributed positioning grooves in the form of a cylinder in the fixed ring body, and the positioning grooves being oriented towards the center of the fixed ring body, a wellhead fixing element fixed at the top center of the fixed ring body and corresponding to the cable in the middle part, a guiding device fixed on the inner wall of the fixed ring body and fixedly connected with the bottom of the wellhead fixing element at the top, a sealing device fixed at the bottom of the guiding device and coaxially arranged with the guiding device and provided with a passage corresponding to the cable in the middle part, an inner tube fixed at the bottom of the sealing device, and a pressure relief device arranged between the inner tube and the sleeve. The well sealing device realizes the integration of well sealing and blowout control functions, guarantees the free movement of the cable, and improves the operation safety, reliability and maintenance convenience.

Description

Technical Field

[0001] This invention relates to the field of wellhead safety technology in well logging, and more specifically, to a well sealing device for well logging. Background Technology

[0002] In logging operations of oil and gas wells, geothermal wells, and other similar wells, wireline logging operations require maintaining a safe and controllable pressure environment at the wellhead while allowing continuous lowering and lowering of the wireline and logging tools. If the wellhead seal between the wireline and the wellhead is unreliable, high-pressure oil, gas, water, or other media can easily escape along the outer surface of the wireline, leading to wellhead leakage or even ejection, seriously threatening personal safety and the safety of surface equipment. In actual production, traditional well sealing devices have significant technical defects: the sealing system is prone to wear due to the reciprocating motion of the wireline, increasing the risk of leakage under high pressure; the guiding mechanism lacks adaptive adjustment capability, resulting in severe wireline wear and high movement resistance, affecting logging efficiency; the pressure control system has fragmented functions and a sluggish pressure relief response, leading to unstable wellhead pressure. Therefore, it is necessary to provide a well sealing device for logging to solve the problems mentioned in the background. Summary of the Invention

[0003] To achieve the above objectives, the present invention provides the following technical solution: a well sealing device for well logging, comprising:

[0004] The casing is fixed to the inner wall of the logging well.

[0005] The fixed ring is fixed on the inner wall of the casing at the wellhead. It has multiple ring-shaped positioning grooves inside, which are cylindrical in shape and face the center of the fixed ring.

[0006] The wellhead fixing component is fixed to the top center of the fixing ring body, and the middle part corresponds to the cable;

[0007] The guide device is fixed on the inner wall of the fixed ring, and its top is fixedly connected to the bottom of the wellhead fixing component;

[0008] The sealing device is fixed to the bottom of the guide device and is coaxially arranged with the guide device, with a channel in the middle corresponding to the cable;

[0009] The inner tube is fixed at the bottom of the sealing device;

[0010] The pressure relief device is installed between the inner tube and the outer sleeve.

[0011] Furthermore, preferably, the guiding device includes:

[0012] The control ring is fixed to the inner wall of the fixed ring.

[0013] Multiple moving channels are arranged in a ring shape, radially penetrating the control ring body and corresponding to the positioning slots in the fixed ring body;

[0014] Multiple balls are arranged in a ring and are rolled in the moving channel, fitting against the side wall of the cable;

[0015] The automatic adjustment component has one end movable within the moving channel and the other end fixed within the positioning groove in the fixed ring, and the ball bearing is tactilely connected to the automatic adjustment component.

[0016] Furthermore, preferably, the automatic adjustment component includes:

[0017] The connecting arc body is movable within the moving channel and is connected to the rotating ball bearing.

[0018] The fixed circular surface is fixed inside the positioning groove in the fixed ring body and is located at the end of the positioning groove away from the center;

[0019] A compression spring connects the fixed circular surface and the connecting arc.

[0020] Furthermore, preferably, the sealing device includes:

[0021] The positioning ring is located at the bottom of the guide device;

[0022] Two limiting ring surfaces are symmetrically distributed vertically, with the outer ring fixed to the positioning ring and the upper limiting ring surface fixedly connected to the bottom of the guide device;

[0023] The sealing components are arranged in two sets, one above the other, between the limiting ring surfaces. Each set has multiple sealing components arranged in a ring, and the sealing components in the two sets are staggered.

[0024] The elastic arc plate is set in accordance with the sealing component, with its two ends fixedly connected to the inner wall of the positioning ring and its middle part fixedly connected to the sealing component.

[0025] Furthermore, preferably, the sealing assembly includes:

[0026] A closed arc body, one side of which is slidably connected to a limiting annular surface, and the other side of which is slidably connected to another closed arc body in another group;

[0027] The connecting arc plate is fixed at the outer arc of the closed arc body and is fixedly connected to the elastic arc plate.

[0028] Two fixed columns, shaped like semi-cylinders, are symmetrically distributed and fixed on both sides of the closed arc.

[0029] The fitting mechanism is located at the inner arc of the closed arc body, and its two ends are fixedly connected to the fixed column.

[0030] Furthermore, preferably, the bonding mechanism includes:

[0031] Two connectors are symmetrically distributed and fixedly connected to the fixed column, and the connectors are located inside the closed arc and the fixed column.

[0032] The flexible bonding surface corresponds to the inner arc of the closed arc body, is fixed between the two connecting parts, and fits against the side wall of the cable;

[0033] Two flexible adjustment surfaces are symmetrically distributed on the top and bottom, connecting the flexible bonding surface and the inner arc of the closed arc body.

[0034] Furthermore, as a preferred embodiment, a microporous oil injection system is connected to the flexible bonding surface. The microporous oil injection system is set in the closed arc body and injects high-temperature resistant grease through a micro-pump to form a dynamic lubricating film between the cable and the flexible bonding surface.

[0035] Furthermore, preferably, the pressure relief device includes:

[0036] The movable ring is positioned between the sleeve and the inner tube.

[0037] A buffer ring is positioned between the moving ring and the fixed ring;

[0038] Multiple connecting columns are arranged in a ring and are offset from the positioning groove in the fixed ring. The top of the connecting column is fixedly connected to the fixed ring, and the bottom is slidably connected to the moving ring and the buffer ring. A pressure relief hole is provided on the inner side of the bottom of the connecting column.

[0039] Compared with the prior art, the beneficial effects of the present invention are:

[0040] In this invention, the rolling connection between the ball bearings in the guide device and the automatic adjustment component achieves the effects of adaptively adapting to changes in cable diameter, reducing frictional resistance, and ensuring free movement and precise guidance.

[0041] By coordinating the upper and lower sets of staggered sealing components and the elastic arc plate in the sealing device, the effects of constructing multiple sealing barriers, adapting to cable surface irregularities, and eliminating micro-leakage channels are achieved.

[0042] By setting up an elastic connection between the flexible bonding surface and the flexible adjustment surface in the bonding mechanism, the effect of adapting to the micro-undulations of the cable, forming a gapless bonding, and forming a dynamic lubricating film in conjunction with the micro-pore oil injection system is achieved.

[0043] By linking the moving ring and the buffer ring in the pressure relief device, the effects of pressure buffering, rapid pressure relief beyond the threshold, and maintaining stable wellhead pressure are achieved.

[0044] The overall device achieves integrated wellhead sealing and blowout prevention control through a coordinated design of guidance, sealing, and pressure relief, ensuring the free movement of the cable while improving operational safety and reliability. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the overall structure of a well sealing device used for logging.

[0046] Figure 2 This is a schematic diagram of the guiding device structure;

[0047] Figure 3 This is a schematic diagram of the automatic adjustment component structure;

[0048] Figure 4 This is a schematic diagram of the sealing device structure;

[0049] Figure 5 This is a schematic diagram of the sealing assembly structure;

[0050] Figure 6 To fit the schematic diagram of the mechanism;

[0051] Figure 7 This is a schematic diagram showing the positional relationship between the upper and lower sealing components;

[0052] Figure 8 This is a schematic diagram of the pressure relief device.

[0053] In the diagram: 1. Casing; 2. Fixed ring; 3. Wellhead fixing component; 4. Guide device; 5. Sealing device; 6. Inner tube; 7. Pressure relief device; 41. Control ring; 42. Moving channel; 43. Ball bearing; 44. Automatic adjustment component; 51. Positioning ring; 52. Restricting ring surface; 53. Sealing component; 54. Elastic arc plate; 71. Moving ring; 72. Buffer ring; 73. Connecting column; 441. Connecting arc; 442. Fixed circular surface; 443. Compression spring; 531. Closed arc; 532. Connecting arc plate; 533. Fixed column; 534. Fitting mechanism; 5341. Connector; 5342. Flexible fitting surface; 5343. Flexible adjustment surface. Detailed Implementation

[0054] Please see Figures 1 to 8 In this embodiment of the invention, a well sealing device for logging includes:

[0055] Casing 1 is fixed to the inner wall of the logging well;

[0056] The fixed ring 2 is fixed on the inner wall of the casing 1 at the wellhead. It has multiple ring-shaped positioning grooves inside, which are cylindrical in shape and face the center of the fixed ring 2.

[0057] Wellhead fixing component 3 is fixed at the top center of the fixing ring 2, and the middle part corresponds to the cable;

[0058] The guide device 4 is fixed on the inner wall of the fixed ring 2, and its top is fixedly connected to the bottom of the wellhead fixing part 3;

[0059] The sealing device 5 is fixed to the bottom of the guide device 4 and is coaxially arranged with the guide device 4, with a channel in the middle corresponding to the cable;

[0060] The inner tube 6 is fixed to the bottom of the sealing device 5;

[0061] The pressure relief device 7 is installed between the inner tube 6 and the sleeve 1.

[0062] In this embodiment, the guiding device 4 includes:

[0063] The control ring 41 is fixed on the inner wall of the fixed ring 2;

[0064] Multiple moving channels 42 are arranged in a ring and radially penetrate the control ring 41, corresponding to the positioning grooves in the fixed ring 2.

[0065] Multiple balls 43 are arranged in a ring and are rolled in the moving channel 42, fitting against the side wall of the cable.

[0066] The automatic adjustment component 44 has one end movable within the moving channel 42 and the other end fixed within the positioning groove in the fixed ring 2, and the ball 43 is tactilely connected to the automatic adjustment component 44.

[0067] In other words, when the cable passes through the wellhead fixing component 3 and enters the guiding device 4, the ball bearing 43 rolls within the moving channel 42 to perform radial displacement and compresses the automatic adjustment component 44 to adapt to the cable size. The automatic adjustment component 44 is always in contact with the cable sidewall to achieve dynamic guidance, ensuring the cable moves freely while maintaining precise guidance, adapting to the logging needs of cables with different diameters. In addition, the casing 1 is fixed to the inner wall of the well as the basic support structure of the device, while the fixing ring 2 is fixed to the inner wall of the casing 1 at the wellhead. The ring 2 has annularly distributed cylindrical positioning grooves inside, with the groove openings facing the center. Together, they form the wellhead positioning frame, which not only ensures the stable connection between the device and the well wall, but also provides a precise installation reference for the subsequent guiding and sealing structures through the positioning grooves. The rigid fixing of the casing 1 ensures the overall structural stability, and the positioning groove design of the fixing ring 2 enables modular assembly of components, improving installation efficiency and maintenance convenience.

[0068] In this embodiment, the automatic adjustment component 44 includes:

[0069] The connecting arc body 441 is movably positioned within the moving channel 42 and rotatably connected to the ball bearing 43;

[0070] The fixed circular surface 442 is fixed inside the positioning groove in the fixed ring 2 and is located at the end of the positioning groove away from the center;

[0071] Compression spring 443 connects fixed circular surface 442 and connecting arc body 441.

[0072] In other words, when the cable passes through the wellhead fixing part 3 and enters the guide device 4, the ball 43 rolls within the moving channel 42 to perform radial displacement. Simultaneously, the ball 43 rolls on the connecting arc body 441 and compresses the compression spring 443. The portion of the ball 43 protruding from the moving channel 42 is dynamically adjusted to adapt to the cable specifications. Under the combined action of the fixed circular surface 442 and the compression spring 443, the compression spring 443 pushes the connecting arc body 441 to keep the ball 43 always in contact with the side wall of the cable, achieving dynamic positioning and guidance. The rolling design of the ball 43 effectively reduces the frictional resistance of the cable. The spring-arc structure of the automatic adjustment component 44 achieves adaptive radial adjustment, ensuring free movement of the cable while maintaining accurate guidance, adapting to the logging needs of cables with different diameters.

[0073] In this embodiment, the sealing device 5 includes:

[0074] Positioning ring 51 is located at the bottom of guide device 4;

[0075] Two limiting ring surfaces 52 are symmetrically distributed vertically. The outer ring is fixed to the positioning ring 51, and the upper limiting ring surface 52 is fixedly connected to the bottom of the guide device 4.

[0076] The sealing components 53 are arranged in two groups, one above the other, and are positioned between the limiting annular surfaces 52. Each group has multiple sealing components arranged in a ring, and the sealing components 53 in the upper and lower groups are staggered.

[0077] The elastic arc plate 54 is provided corresponding to the sealing component 53, with its two ends fixedly connected to the inner wall of the positioning ring 51 and its middle part fixedly connected to the sealing component 53.

[0078] In other words, after the cable passes through the guide device 4, the cable is in a vertical state. Then, when the cable passes through the sealing device 5, under the restriction of the positioning ring 51, the elastic arc plate 54 and the cable control the position of the sealing component 53. The sealing component 53 slides on the limiting ring surface 52 and fits against the cable sidewall to form a seal. Under the combined action of the upper and lower sealing components 53, the annular gap between the cable sidewall and the limiting ring surface 52 is completely closed.

[0079] In this embodiment, the sealing assembly 53 includes:

[0080] The closed arc 531 is slidably connected to the limiting annular surface 52 on one side and to the closed arc 531 in another group on the other side.

[0081] The connecting arc plate 532 is fixed at the outer arc of the closed arc body 531 and is fixedly connected to the elastic arc plate 54.

[0082] The fixed column 533 is a semi-cylindrical shape, and two are symmetrically distributed and fixed on both sides of the closed arc 531;

[0083] The fitting mechanism 534 is located at the inner arc of the closed arc body 531, and its two ends are fixedly connected to the fixed column 533 respectively.

[0084] In other words, the sealing assembly 53 adopts a staggered annular distribution design with two sets of upper and lower components. When the cable passes through, the elastic arc plate 54 applies radial extrusion force to the closed arc body 531 through the connecting arc plate 532, driving the closed arc body 531 to contract towards the center along the limiting annular surface 52. At this time, the semi-cylindrical fixed columns 533 fixed on both sides of the closed arc body 531 move synchronously, driving the bonding mechanism 534 to move closer to the cable sidewall, and finally forming a tight fit with the cable surface. The elastic deformation characteristics of the elastic arc plate 54, in conjunction with the connecting arc plate 532, enable the closed arc body 531 to adapt to changes in cable diameter, and drive the bonding mechanism 534 to adapt to the logging requirements of cables of different specifications. Since the upper and lower sealing assemblies 53 are staggered, the closed arc body 531 of the upper component and the closed arc body 531 of the lower component form a cross sealing area in the radial direction, constructing multiple sealing barriers to effectively resist high-pressure fluid leakage at the wellhead.

[0085] It should be noted that, under the cable diameter limitation, when the sealing assembly 53 moves outward, the closed arc 531 in the upper and lower sets of sealing assemblies 53 always overlaps. Thus, the second set of sealing assemblies 53 seals the gap generated by the single set of sealing assemblies 53 during the movement, so that the sealing assembly 53 seals the area corresponding to the closed arc 531 during the movement and adjustment process, and under the action of the bonding mechanism 534, it fully seals the gap between the cable sidewall and the limiting ring surface 52.

[0086] In this embodiment, the bonding mechanism 534 includes:

[0087] Two connectors 5341 are symmetrically distributed and are fixedly connected to the fixed column 533. The connectors 5341 are located inside the closed arc 531 and the fixed column 533.

[0088] The flexible bonding surface 5342 corresponds to the inner arc of the closed arc body 531, is fixed between the two connecting parts 5341, and is bonded to the side wall of the cable.

[0089] Two flexible adjustment surfaces 5343 are symmetrically distributed on the top and bottom, connecting the flexible bonding surface 5342 and the inner arc of the closed arc 531.

[0090] In other words, the connector 5341 is rigidly connected to the closed arc body 531 through the fixed column 533, ensuring that the entire mechanism moves synchronously with the closed arc body 531. When the closed arc body 531 is squeezed towards the center by the elastic arc plate 54, the connector 5341 drives the flexible bonding surface 5342 to bond with the side wall of the cable. At this time, the flexible adjustment surface 5343 undergoes elastic deformation, absorbing the slight irregularities on the cable surface, ensuring that the flexible bonding surface 5342 and the cable surface form a gapless contact. The flexible bonding surface 5342 is made of highly elastic silicone rubber material, which, together with the flexible adjustment surface 5343, can adapt to the micro-undulations of the cable surface, ensuring the sealing surface is bonded and eliminating micro-leakage channels.

[0091] In this embodiment, a microporous oil injection system is connected to the flexible bonding surface 5342. The microporous oil injection system is set inside the closed arc body 531 and injects high-temperature resistant grease through a micro-pump to form a dynamic lubricating film between the cable and the flexible bonding surface 5342.

[0092] In other words, while the flexible bonding surface 5342 is bonded to the cable surface, the microporous oil injection system pre-installed in the closed arc body 531 continuously injects high-temperature resistant grease (such as silicone-based grease) into the space between the flexible bonding surface 5342 and the cable through micro-channels inside the flexible bonding surface 5342. This forms a dynamic lubricating film with a thickness of about 0.1 mm on the contact surface, reducing the coefficient of sliding friction, reducing cable wear, and preventing grease carbonization failure under high-temperature conditions. Furthermore, when the flexible bonding surface 5342 is scratched by foreign objects, the microporous oil injection system can inject grease containing repair agents, which forms a repair layer at the scratch through chemical bonding, restoring sealing performance and extending the service life of the component.

[0093] In this embodiment, the pressure relief device 7 includes:

[0094] The movable ring 71 is movably positioned between the sleeve 1 and the inner tube 6;

[0095] A buffer ring 72 is disposed between the movable ring 71 and the fixed ring 2;

[0096] Multiple connecting posts 73 are arranged in a ring and are offset from the positioning groove in the fixed ring 2. The top is fixedly connected to the fixed ring 2, and the bottom is slidably connected to the moving ring 71 and the buffer ring 72. A pressure relief hole is provided on the inner side of the bottom of the connecting post 73.

[0097] In other words, when the wellhead pressure increases, the moving ring 71 moves towards the fixed ring 2 under pressure, compressing the buffer ring 72 to achieve pressure buffering and allowing the connecting column 73 to leak out. When the pressure exceeds the threshold, the bottom of the moving ring 71 moves to the position of the pressure relief hole on the connecting column 73, discharging the excess pressure through the connecting column 73 and maintaining the wellhead pressure stability. Furthermore, the linkage design between the moving ring 71 and the buffer ring 72 achieves pressure buffering, avoiding instantaneous high-pressure impacts. The pressure relief hole of the connecting column 73 is linked with the position of the moving ring 71 to perform rapid pressure relief, ensuring the safe operation of the device in a high-pressure environment.

[0098] In practice, the cable is first guided into the guide device 4 via the wellhead fixing component 3. The inner ball bearing 43 rolls in the moving channel 42 and compresses the compression spring 443 of the automatic adjustment component 44. Dynamic contact and guidance with the cable sidewall are achieved through the radial adjustment of the connecting arc body 441. Then, the cable continues to descend to the sealing device 5. The elastic arc plate 54 drives the upper and lower sets of staggered sealing components 53 to contract towards the center along the limiting ring surface 52 through the connecting arc plate 532. The closing arc body 531 drives the flexible contact surface of the fixed column 533 and the contact mechanism 534. 5342 fits tightly against the cable surface, and the flexible adjustment surface 5343 absorbs surface irregularities. At the same time, the micro-orifice oil injection system injects high-temperature resistant grease to form a dynamic lubrication film, achieving multiple seals and friction reduction. When the wellhead pressure rises, the moving ring 71 of the pressure relief device 7 moves under pressure towards the fixed ring 2 to compress the buffer ring 72. When the pressure exceeds the threshold, the pressure relief hole of the connecting column 73 opens to release the pressure. Finally, through the positioning frame support, guidance, sealing and pressure relief of the casing 1 and the fixed ring 2, the wellhead is sealed while ensuring the free movement of the cable.

[0099] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A well sealing device for logging, characterized in that: include: The casing (1) is fixed on the inner wall of the logging well; The fixed ring (2) is fixed on the inner wall of the casing (1) at the wellhead. It has multiple ring-shaped positioning grooves inside, which are cylindrical and face the center of the fixed ring (2). The wellhead fixing component (3) is fixed at the top center of the fixing ring (2), and the middle part corresponds to the cable; The guide device (4) is fixed on the inner wall of the fixed ring (2), and its top is fixedly connected to the bottom of the wellhead fixing component (3); The sealing device (5) is fixed at the bottom of the guide device (4) and is coaxially arranged with the guide device (4), with a channel in the middle corresponding to the cable; The inner tube (6) is fixed to the bottom of the sealing device (5); A pressure relief device (7) is installed between the inner tube (6) and the sleeve (1); The sealing device (5) includes: A positioning ring (51) is set at the bottom of the guide device (4); Two limiting ring surfaces (52) are symmetrically distributed on the top and bottom. The outer ring is fixed on the positioning ring (51), and the upper limiting ring surface (52) is fixedly connected to the bottom of the guide device (4). The sealing components (53) are arranged in two groups, one above the other, between the limiting ring surfaces (52). Each group has multiple sealing components arranged in a ring, and the sealing components (53) in the upper and lower groups are staggered. The elastic arc plate (54) is provided corresponding to the sealing component (53), with its two ends fixedly connected to the inner wall of the positioning ring (51) and its middle part fixedly connected to the sealing component (53); The sealing assembly (53) includes: The closed arc (531) is slidably connected to the limiting ring surface (52) on one side and slidably connected to the closed arc (531) in another group on the other side; The connecting arc plate (532) is fixed at the outer arc of the closed arc body (531) and is fixedly connected to the elastic arc plate (54); The fixed column (533) is a semi-cylindrical shape, with two symmetrically distributed and fixed on both sides of the closed arc (531); The fitting mechanism (534) is set at the inner arc of the closed arc body (531), and its two ends are fixedly connected to the fixed column (533); The bonding mechanism (534) includes: Two connectors (5341) are symmetrically distributed and are fixedly connected to the fixed column (533), and the connectors (5341) are located inside the closed arc (531) and the fixed column (533); The flexible bonding surface (5342) corresponds to the inner arc of the closed arc body (531), and is fixed between the two connecting parts (5341) and bonded to the side wall of the cable; The flexible adjustment surface (5343) has two symmetrically distributed surfaces, which connect the flexible bonding surface (5342) and the inner arc of the closed arc (531).

2. A well-sealing device for logging according to claim 1, characterized in that: The guiding device (4) includes: The control ring (41) is fixed on the inner wall of the fixed ring (2); The moving channel (42) is provided in multiple rings, which radially penetrate the control ring (41) and correspond to the positioning groove in the fixed ring (2); Multiple balls (43) are arranged in a ring and are rolled in the moving channel (42) to fit against the side wall of the cable; The automatic adjustment component (44) has one end movable in the moving channel (42) and the other end fixed in the positioning groove in the fixed ring (2), and the ball (43) is tumbledly connected to the automatic adjustment component (44).

3. A well-sealing device for logging according to claim 2, characterized in that: The automatic adjustment component (44) includes: The connecting arc body (441) is movable within the moving channel (42) and rotatably connected to the ball bearing (43); The fixed circular surface (442) is fixed inside the positioning groove in the fixed ring body (2) and is located at the end of the positioning groove away from the center; Compression spring (443), connecting fixed circular surface (442) and connecting arc body (441).

4. A well-sealing device for logging according to claim 1, characterized in that: A microporous oil injection system is connected to the flexible bonding surface (5342). The microporous oil injection system is set inside the closed arc body (531) and injects high-temperature resistant grease through a micro pump to form a dynamic lubricating film between the cable and the flexible bonding surface (5342).

5. A well-sealing device for logging according to claim 1, characterized in that: The pressure relief device (7) includes: The movable ring (71) is movable between the sleeve (1) and the inner tube (6); A buffer ring (72) is disposed between a movable ring (71) and a fixed ring (2); The connecting column (73) is provided in multiple rings and is offset from the positioning groove in the fixed ring (2). The top is fixedly connected to the fixed ring (2), and the bottom is slidably connected to the moving ring (71) and the buffer ring (72). The bottom inner side of the connecting column (73) is provided with a pressure relief hole.

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