Wellhead device for replacing a gate valve of a Christmas tree under pressure

Abstract

The application relates to a wellhead device for replacing a gate valve of an oil tree under pressure and belongs to the field of petroleum industry, which comprises a first sealing assembly, a ventilation pipeline, a fixing part, an inflation sealing part and a tightening part, the fixing part is fixed with one end of the ventilation pipeline, the fixing part is fixed with the inflation sealing part, the ventilation pipeline is communicated with the inflation sealing part, the inflation sealing part is arranged in the tightening part, the inflation sealing part can abut against the inner ring surface of the oil tree, the tightening part can move outward along the radial direction and extrude the inflation sealing part, the first sealing assembly comprises a driving part and a rotating rod fixed with the output end of the driving part, the rotating rod is fixed with the tightening part, the rotating rod is movably arranged in the ventilation pipeline along the radial direction, the ventilation pipeline is spaced from the rotating rod, and the gate valve can be replaced without stopping production and pressure relief.

Description

Technical Field

[0001] This invention relates to the petroleum industry, and in particular to a wellhead device for replacing gate valves under pressure in a wellhead. Background Technology

[0002] The Christmas tree gate valve is a core wellhead control device installed on the Christmas tree. It is a type of gate valve where the gate moves linearly along the vertical line of the valve seat to cut off or allow fluid flow. Its main functions include controlling oil and gas production, ensuring emergency well shut-in safety, and supporting downhole operations such as acid fracturing and water injection. During oilfield production, the Christmas tree gate valve is subjected to harsh conditions such as high pressure, corrosive media, and fluid erosion. Its valve plate, valve seat, valve stem, sealing packing, and bearings are highly susceptible to corrosion, wear, and aging of seals, requiring timely replacement of faulty gate valves.

[0003] However, current routine gate valve maintenance and replacement operations require production to be stopped and well pressure released first. Stopping production will interrupt oil production and affect the production schedule; releasing pressure will require pumping back the large amount of chemicals and water already injected downhole into the tanker truck, and then injecting them again after the replacement is completed, which not only greatly increases the workload, but is also time-consuming and labor-intensive. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defect of the prior art that requires production to be stopped and pressure released to replace the wellhead gate valve, thereby providing a working wellhead device for replacing the wellhead gate valve under pressure.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A working wellhead device for replacing gate valves under pressure at an oil production tree, comprising an oil production tree, including: The first sealing assembly includes a venting pipe, a fixing member, an inflatable seal, and a tightening member. The fixing member is fixed to one end of the venting pipe and the inflatable seal. The venting pipe is connected to the inflatable seal. The inflatable seal is disposed inside the tightening member. The inflatable seal can abut against the inner annular surface of the tree. The tightening member can move radially outward and compress the inflatable seal.

[0006] Preferably, the first sealing assembly includes a driving member and a rotating rod fixed to the output end of the driving member. The rotating rod is fixed to the clamping member and is movably inserted into the ventilation pipe along the radial direction. The ventilation pipe and the rotating rod are spaced apart. Alternatively, the first sealing assembly includes a handwheel and a rotating rod fixed to the handwheel, the rotating rod being fixed to the clamping member, the rotating rod being movably inserted into the vent pipe along the radial direction, and the vent pipe and the rotating rod being spaced apart.

[0007] Preferably, the clamping member includes a rotating part, a fixed part, a moving part, and an arc-shaped part. The rotating rod is fixed to the rotating part, the fixed part is fixed to the fixing member, one end of the moving part near the fixed part is slidably connected to the rotating part, and one end of the moving part away from the fixed part is fixed to the arc-shaped part. The moving part can move radially outward, and the arc-shaped part can abut against the inner ring surface of the inflatable seal.

[0008] Preferably, the rotating part has a plurality of spaced arc-shaped grooves, the clamping member includes a protrusion, the protrusion is slidably connected to the arc-shaped groove, the lower side of the fixing part has a limiting groove, and the moving part is slidably connected to the limiting groove.

[0009] Preferably, the first sealing assembly further includes a vent pipe, the fixing member has a plurality of vent grooves, the vent pipe passes through the vent grooves, and the outlet end of the vent pipe faces the arc-shaped portion.

[0010] Preferably, a second sealing assembly is included, comprising a seal and a compression member. The seal is movably inserted through the vent pipe, and the compression member is sleeved on the vent pipe, extending vertically upward. The compression member is located above the seal, and a protrusion is provided at the lower end of the compression member, which can compress the seal.

[0011] Preferably, the device further includes a fixing component, which includes a support member, a limiting member, and a plug-in member. The support member is fixed to the plug-in member, and the limiting member is threadedly connected to the support member. The limiting member can be fixed to the ventilation pipe.

[0012] Preferably, the fixing component further includes a plurality of nuts, the plug-in component includes a plug-in portion and an annular portion fixed to the plug-in portion, the plug-in portion is conical, the annular portion is provided with a plurality of threaded holes, and the plurality of nuts are threadedly connected to the threaded holes.

[0013] Preferably, the first sealing assembly further includes an inflation component, which can be fixed to the support component, and the input end of the inflation component is connected to the ventilation pipe.

[0014] Preferably, the fixing component further includes a snap-fit ​​member, the upper end of the ventilation pipe is provided with a snap-fit ​​part, the snap-fit ​​member is movably inserted through the ventilation pipe, the outer diameter of the snap-fit ​​member is larger than the outer diameter of the extrusion member, the inner diameter of the snap-fit ​​member is smaller than the inner diameter of the extrusion member, the snap-fit ​​member is provided with a snap-fit ​​groove and an elastic part, and the snap-fit ​​part can snap into the snap-fit ​​groove.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The wellhead device for replacing gate valves under pressure at the wellhead, as provided in the above technical solution, includes a first sealing component comprising a ventilation pipe, a fixing component, an inflation seal, and a tightening component. Gas flows into the ventilation pipe and inflates the inflation seal, causing it to expand and abut against the inner annular surface of the wellhead to form an initial seal. Simultaneously, the tightening component radially pushes the inflation seal outward, causing it to undergo elastic deformation to enhance the radial sealing force. This establishes a reliable sealing barrier under wellhead pressure, allowing for gate valve replacement without production shutdown and depressurization. This effectively solves the problems of interrupted oil production operations due to production shutdown and depressurization, and the increased workload, time, and labor costs associated with repeated pumping of chemical agents and injected water in existing technologies. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 A schematic diagram of a working wellhead device for replacing gate valves under pressure in an embodiment of the present invention; Figure 2 for Figure 1 A magnified view of part A shown; Figure 3 This is a cross-sectional view of the wellhead device for replacing the gate valve under pressure in an embodiment of the present invention; Figure 4 for Figure 3 A magnified view of part B shown; Figure 5 This is a cross-sectional view of a working wellhead device for replacing gate valves under pressure in a partial embodiment of the present invention; Figure 6 for Figure 5 A magnified view of part C shown; Figure 7 for Figure 5 A magnified view of part D shown; Figure 8 An exploded view of a portion of the first sealing assembly provided in an embodiment of the present invention; Figure 9 for Figure 8 A magnified view of part F shown; Figure 10 This is a schematic diagram of a portion of the first sealing assembly provided in an embodiment of the present invention; Figure 11 for Figure 10 A magnified view of part G shown.

[0018] Explanation of reference numerals in the attached figures: 1. First sealing assembly; 11. Ventilation pipe; 111. Snap-fit ​​part; 12. Fixing member; 121. Ventilation groove; 13. Inflatable sealing member; 14. Tightening member; 141. Rotating part; 1411. Arc groove; 142. Fixing part; 143. Moving part; 144. Arc part; 145. Protrusion; 15. Rotating rod; 16. Ventilation pipe; 2. Second sealing assembly; 21. Sealing member; 22. Extrusion member; 3. Fixing assembly; 31. Support member; 32. Limiting member; 33. Insertion member; 331. Insertion part; 332. Annular part; 34. Snap-fit ​​part; 341. Snap-fit ​​groove; 342. Elastic part; 4. Christmas tree. Detailed Implementation

[0019] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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 the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] Please refer to the following carefully. Figures 1 to 11 This invention relates to a working wellhead device for replacing gate valves under pressure in a production tree, comprising a first sealing component 1, a second sealing component 2, and a fixing component 3. The first sealing component 1 provides a first sealing function, the second sealing component 2 provides a second sealing function, and the fixing component 3 is mainly used to fix the first sealing component 1 and the second sealing component 2. In addition, both the first sealing component 1 and the second sealing component 2 are inserted into the production tree 4 during use and fixed by the fixing component 3.

[0022] Specifically, the first sealing assembly 1 includes a ventilation pipe 11, a fixing member 12, an inflatable sealing member 13, and a tightening member 14. The material of the inflatable sealing member 13 can be nitrile rubber, hydrogenated nitrile rubber, fluororubber, or special fluororubber, etc. The cross-section of the inflatable sealing member 13 is U-shaped after inflation. The fixing member 12 is fixed to one end of the ventilation pipe 11. The fixing method can be welding. The diameter of the fixing member 12 is smaller than the diameter of the Christmas tree 4 to ensure that the first sealing assembly 1 can extend into the Christmas tree 4. The fixing member 12 is fixed to the inflation seal 13. The fixing method is not limited. The ventilation pipe 11 is connected to the inflation seal 13. The tightening member 14 is set inside the inflation seal 13 to inflate the inflation seal 13 with gas. The inflation seal 13 is annular. The outer ring surface of the inflation seal 13 abuts against the inner ring surface of the Christmas tree 4 to form the first sealing effect. The tightening member 14 can move radially outward and squeeze the inflation seal 13, causing the inflation seal 13 to undergo elastic deformation and enhance the sealing performance. The first sealing assembly 1 also includes an inflation member, which can be an electric air pump. The inflation member can be fixed to the support member 31; or, please read carefully. Figure 1 A placement frame is fixed on the crossbeam on the upper side of the support member 31. The electric air pump can be placed in the placement frame. The input end of the air inflator is connected to the air pipe 11. The upper end of the air pipe 11 is also provided with an air inlet for connecting to the electric air pump to inflate gas into the air sealing member 13.

[0023] There are three ways to fix the inflatable seal 13 to the fixing member 12. The first way is to process a groove on the lower side of the fixing member 12, embed the inflatable seal 13 into the groove, and use the radial force generated by the inflation to achieve a tight seal. The fixing plate is pressed with bolts or other fasteners to form a firm limit. After use, if the inflatable seal 13 is damaged or has a large amount of oil adhering to it, this fixing method can replace the inflatable seal 13. The second way is to permanently bond the seal 21 to the metal air inlet and other components. The third way is to use a fastening steel hook to hook the flange groove and achieve the sealing of the Christmas tree 4 through inflation pressure.

[0024] Please read carefully. Figures 5 to 7 The first sealing assembly 1 includes a driving component and a rotating rod 15 fixed to the output end of the driving component. The driving component can be a rotary motor. The rotating rod 15 is fixed to the clamping member 14. The rotating rod 15 is movably inserted into the ventilation pipe 11 along the radial direction. The ventilation pipe 11 and the rotating rod 15 are spaced apart. When the rotary motor is started, it drives the rotating rod 15 to rotate, thereby driving the clamping member 14 to rotate, causing the clamping member 14 to move radially outward, compressing the inflatable sealing member 13 and enhancing the first sealing effect. Alternatively, the first sealing assembly 1 includes a cam and a rotating rod 15 fixed to the cam. The operator can manually rotate the cam to achieve the technical effect achievable by the above-mentioned technical features.

[0025] Please read carefully. Figures 8 to 11 The clamping member 14 includes a rotating part 141, a fixed part 142, a moving part 143, and an arc-shaped part 144. The rotating part 141 and the fixed part 142 are both circular. The fixed part 142 has a through groove at its central axis. The moving part 143 can be elongated or cylindrical. The arc-shaped part 144 can be understood as a segment of an annular ring. The rotating rod 15 passes through the through groove and is fixed to the central axis of the rotating part 141. The fixed part 142 is fixed to the fixing member 12. Multiple connecting rods can be provided. One end of the connecting rod is fixed to the fixing member 12, and the other end of the connecting rod is fixed to the fixed part 142. The fixed part 142 is fixed to the fixing member 12 through the connecting rods. The end of the moving part 143 near the fixed part 142 is slidably connected to the rotating part 141, and the end of the moving part 143 away from the fixed part 142 is fixed to the arc-shaped part 144. The moving part 143 can move radially outward.

[0026] Please refer to the following carefully. Figure 11 The rotating part 141 has multiple evenly spaced arc-shaped grooves 1411. The clamping member 14 includes a protrusion 145, which is slidably connected to the arc-shaped grooves 1411. The protrusion 145 drives the moving part 143 and the arc-shaped part 144 to reciprocate along the arc-shaped grooves 1411, and the diameters of the moving part 143 and the arc-shaped part 144 gradually increase or decrease. The lower side of the fixed part 142 has a limiting groove. In the vertical direction, the projection of the limiting groove overlaps with the projection of the moving part 143. The shape of the limiting groove matches the shape of the moving part 143. The moving part 143 is slidably connected to the limiting groove, so that the protrusion 145 and the arc-shaped groove 1411 reciprocate linearly in the radial direction. That is, the limiting groove mainly serves to limit the movement direction of the moving part 143. When the rotary motor starts, it drives the rotating rod 15 to rotate, which in turn drives the rotating part 141 to rotate. At this time, the fixed part 142 remains stationary. Utilizing the principle of mechanical linkage, the evenly distributed moving parts 143 move along the radial limiting grooves. When the central shaft rotates, the moving parts 143, driven by the rotating rod 15, move radially outward or inward. The moving rod drives the arc-shaped part 144 to move radially outward. The arc-shaped part 144 compresses the inflatable seal 13, causing the inflatable seal 13 to undergo elastic deformation, thereby enhancing the first layer of sealing.

[0027] The first sealing assembly 1 also includes a vent pipe 16, which includes a vent pipe 16 and a limiting part communicating with the vent pipe 16. The limiting part is annular and has a square protrusion on its lower side. The fixing member 12 has multiple vent grooves 121 and recessed grooves. The vent grooves 121 and recessed grooves are not communicating. The vent grooves 121 are annularly arranged. In the vertical direction, the projection of the recessed groove overlaps with the projection of the square protrusion, which limits the vent pipe 16 so that the end of the vent pipe 16 away from the fixing part 142 always faces the arc-shaped part 144. The diameter of the vent groove 121 is smaller than the diameter of the limiting part. Multiple vent pipes 16 are respectively inserted through the vent grooves 121. The outlet ends of the multiple vent pipes 16 face the arc-shaped part 144. At least most of the gas acts on the arc-shaped part 144. The arc-shaped part 144 is subjected to increased force, which squeezes the inflatable sealing member 13. The inflatable sealing member 13 undergoes elastic deformation, thereby enhancing the first sealing effect.

[0028] The second sealing assembly 2 includes a sealing element 21 and a pressing element 22 to achieve a second sealing effect. The sealing element 21 is movably inserted through the ventilation pipe 11, and the pressing element 22 is sleeved on the ventilation pipe 11, extending vertically upward. The pressing element 22 is located above the sealing element 21, and the lower end of the pressing element 22 has a protrusion 145 that can compress the sealing element 21. The diameters of the sealing element 21 and the pressing element 22 are slightly smaller than the inner diameter of the Christmas tree 4 to ensure that the second sealing assembly 2 can extend into the Christmas tree 4. Therefore, the pressing element 22 needs to compress the sealing element 21 axially, causing the sealing element 21 to undergo elastic deformation radially, thereby achieving a second sealing effect.

[0029] Please refer to the following carefully. Figure 1 The fixing component 3 includes a support 31, multiple limiting members 32, a plug-in member 33, and multiple nuts. The lower end of the support 31 is fixed to the plug-in member 33, and the fixing method can be welding. The plug-in member 33 includes a plug-in part 331 and an annular part 332 fixed to the plug-in part 331. The plug-in part 331 is conical and can be inserted into the ground. The annular part 332 is provided with multiple threaded holes. Multiple nuts are threadedly connected to the multiple threaded holes respectively, and the fixing to the ground is achieved through threaded connection. Multiple limiting members 32 are threadedly connected to the support 31 respectively. The limiting members 32 can abut against the ventilation pipe 11, thereby achieving the fixing of the first sealing component 1 and the second sealing component 2.

[0030] Please refer to the following carefully. Figure 7The fixing component 3 also includes a snap-fit ​​component 34. The upper end of the ventilation pipe 11 is provided with a snap-fit ​​part 111. The snap-fit ​​part 111 is fixed to the outer ring surface of the ventilation pipe 11. Along the axial direction downward, the diameter of the outer ring surface of the snap-fit ​​part 111 gradually increases. Along the axial direction, the snap-fit ​​part 111 and the extrusion member 22 are spaced apart. The axial length of the snap-fit ​​component 34 is slightly greater than the distance between the snap-fit ​​part 111 and the extrusion member 22. The snap-fit ​​component 34 is movably inserted through the ventilation pipe 11. The outer diameter of the snap-fit ​​component 34 is greater than the outer diameter of the extrusion member 22, and the inner diameter of the snap-fit ​​component 34 is smaller than the inner diameter of the extrusion member 22. The snap-fit ​​component 34 is provided with a snap-fit ​​groove 341 and an elastic part 342. The snap-fit ​​part 111 can snap into the snap-fit ​​groove 341. When the snap-fit ​​component 34 moves downward along the axial direction, the elastic part 342 moves outward along the radial direction, and the extrusion member 22 moves downward. The extrusion member 22 extrudes the sealing member 21 and maintains the extrusion.

[0031] In actual use, the staff first hoisted the entire device into place, inserting the first sealing component 1 and the second sealing component 2 into the inner cavity of the tree 4. The conical insertion part 331 of the fixing component 3 was then inserted into the ground, and the annular part 332 was locked with a nut to achieve overall stable support of the device. Subsequently, the first sealing operation was initiated. Air was first injected into the annular air-filled sealing component 13 through the air inflator and ventilation pipe 11, causing it to expand and adhere to the inner wall of the tree 4. Simultaneously, the drive unit (rotary motor) was activated or the cam was manually rotated. The rotating rod 15 drove the moving part 143 of the clamping component 14 to move radially outward, and the airflow from the ventilation pipe 16 acted on the arc-shaped part 144, resulting in a total of... The air-filled sealing element 13 undergoes elastic deformation to enhance the radial sealing effect. Then, a second seal is implemented by pressing down the snap-fit ​​element 34 to engage with the snap-fit ​​groove 341 at the upper end of the ventilation pipe 11. The snap-fit ​​element 34 is driven to push the extrusion element 22 axially downward, causing the protrusion 145 at the lower end of the extrusion element 22 to axially compress the sealing element 21, forcing the sealing element 21 to undergo elastic deformation radially, thereby forming an axial compression second seal. Finally, the ventilation pipe 11 is locked by the limiting element 32. Utilizing the dual sealing principle of "radial air-filled compression" and "axial compression tightening", safe sealing is achieved in a pressurized environment at the wellhead, facilitating the subsequent replacement of the Christmas tree 4 gate valve.

[0032] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A working wellhead device for replacing gate valves under pressure at a Christmas tree, comprising a Christmas tree (4), characterized in that, include: The first sealing assembly (1) includes a ventilation pipe (11), a fixing member (12), an inflation seal (13), and a tightening member (14). The fixing member (12) is fixed to one end of the ventilation pipe (11), and the fixing member (12) is fixed to the inflation seal (13). The ventilation pipe (11) is connected to the inflation seal (13). The inflation seal (13) is disposed inside the tightening member (14). The inflation seal (13) can abut against the inner annular surface of the tree (4). The tightening member (14) can move radially outward and squeeze the inflation seal (13).

2. The wellhead device for replacing the gate valve under pressure at the Christmas tree according to claim 1, characterized in that, The first sealing assembly (1) includes a driving member and a rotating rod (15) fixed to the output end of the driving member. The rotating rod (15) is fixed to the clamping member (14). The rotating rod (15) is movably inserted into the ventilation pipe (11) along the radial direction. The ventilation pipe (11) and the rotating rod (15) are spaced apart. Alternatively, the first sealing assembly (1) includes a handwheel and a rotating rod (15) fixed to the handwheel. The rotating rod (15) is fixed to the clamping member (14). The rotating rod (15) is movably inserted into the ventilation pipe (11) in the radial direction. The ventilation pipe (11) and the rotating rod (15) are spaced apart.

3. The wellhead device for replacing the gate valve under pressure at the Christmas tree according to claim 2, characterized in that, The clamping member (14) includes a rotating part (141), a fixed part (142), a moving part (143), and an arc-shaped part (144). The rotating rod (15) is fixed to the rotating part (141), the fixed part (142) is fixed to the fixing member (12), the moving part (143) is slidably connected to the rotating part (141) at one end near the fixed part (142), and the moving part (143) is fixed to the arc-shaped part (144) at one end away from the fixed part (142). The moving part (143) can move radially outward, and the arc-shaped part (144) can abut against the inner ring surface of the inflatable sealing member (13).

4. The wellhead device for replacing the gate valve under pressure at the Christmas tree according to claim 3, characterized in that, The rotating part (141) has a plurality of spaced arc grooves (1411), the clamping member (14) includes a protrusion (145), the protrusion (145) is slidably connected to the arc groove (1411), the lower side of the fixing part (142) has a limiting groove, and the moving part (143) is slidably connected to the limiting groove.

5. The wellhead device for replacing the gate valve under pressure at the Christmas tree according to claim 4, characterized in that, The first sealing assembly (1) further includes a vent pipe (16), the fastener (12) has a plurality of vent grooves (121), the vent pipe (16) passes through the vent grooves (121), and the outlet end of the vent pipe (16) faces the arc-shaped portion (144).

6. The wellhead device for replacing the gate valve under pressure at the Christmas tree according to claim 1, characterized in that, The second sealing assembly (2) includes a seal (21) and a squeeze member (22). The seal (21) is movably inserted through the vent pipe (11). The squeeze member (22) is sleeved on the vent pipe (11) and extends vertically upward. The squeeze member (22) is located above the seal (21). The lower end of the squeeze member (22) is provided with a protrusion (145), which can squeeze the seal (21).

7. The wellhead device for replacing the gate valve under pressure at the Christmas tree according to claim 6, characterized in that, It also includes a fixing component (3), which includes a support (31), a limiting component (32) and a plug (33). The support (31) is fixed to the plug (33), the limiting component (32) is threadedly connected to the support (31), and the limiting component (32) can be fixed to the ventilation pipe (11).

8. The wellhead device for replacing the gate valve under pressure at the Christmas tree according to claim 7, characterized in that, The fixing component (3) also includes a plurality of nuts. The plug-in component (33) includes a plug-in portion (331) and an annular portion (332) fixed to the plug-in portion (331). The plug-in portion (331) is conical. The annular portion (332) is provided with a plurality of threaded holes. The plurality of nuts are threadedly connected to the threaded holes.

9. The wellhead device for replacing the gate valve under pressure at the Christmas tree according to claim 8, characterized in that, The first sealing assembly (1) further includes an inflation component, which can be fixed to the support component (31), and the input end of the inflation component is connected to the ventilation pipe (11).

10. The wellhead device for replacing the gate valve under pressure at the Christmas tree according to claim 9, characterized in that, The fixing component (3) also includes a snap-fit ​​component (34). The upper end of the ventilation pipe (11) is provided with a snap-fit ​​part (111). The snap-fit ​​component (34) is movably inserted through the ventilation pipe (11). The outer diameter of the snap-fit ​​component (34) is larger than the outer diameter of the extrusion part (22). The inner diameter of the snap-fit ​​component (34) is smaller than the inner diameter of the extrusion part (22). The snap-fit ​​component (34) is provided with a snap-fit ​​groove (341) and an elastic part (342). The snap-fit ​​part (111) can snap into the snap-fit ​​groove (341).

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