A wellhead dismounting auxiliary device

Abstract

The application discloses a wellhead dismounting auxiliary device, which improves the technical problems of low efficiency, poor operation convenience and big safety hidden danger during wellhead dismounting. The device comprises a control valve connected to the top of a tubing hanger and used for being connected with a tubing, and a stop valve connected to the top of the tubing hanger. An external hand pump is connected with a downhole safety valve and a gas release valve through the stop valve. When the downhole safety valve and the gas release valve are in a normal open state, the opening and closing of the downhole safety valve and the gas release valve can be controlled by controlling the opening and closing of the stop valve. The application can improve the efficiency of wellhead dismounting operation, improve the operation convenience and reduce the safety hidden danger.

Description

Technical Field

[0001] This invention belongs to the technical field of oil well operation tools, and specifically relates to a wellhead disassembly and assembly auxiliary device. Background Technology

[0002] Currently, when conducting offshore oil and water well tubing operations, considering the handling of complex situations such as reverse circulation well washing after tubing unsealing or encountering stuck tubing during tripping, it is necessary to reconnect the hydraulic control lines of the downhole safety valves and venting valves to the drilling platform after the Christmas tree is dismantled and before the riser and blowout preventer assembly are installed, so as to enable the surface to control the downhole safety valves and venting valves.

[0003] However, after reconnecting the hydraulic control line, interference frequently occurs between the BOP assembly's operating handle and the hydraulic control line when operators open and close the BOP assembly, which affects the pressure testing of the BOP assembly in the tubing string. Simultaneously, there is a risk of squeezing the hydraulic control line during the reconnection of the lift tubing, often resulting in rework. Therefore, reconnecting the hydraulic control line often affects the overall efficiency and safety of wellhead assembly and disassembly operations.

[0004] It is evident that wellhead disassembly and assembly operations in related technologies suffer from problems such as low disassembly and assembly efficiency, poor operational convenience, and significant operational safety hazards. Therefore, improving the efficiency of wellhead disassembly and assembly operations, enhancing operational convenience, and reducing safety hazards are of great significance for achieving efficient wellhead disassembly and assembly. Summary of the Invention

[0005] In order to solve all or some of the above problems, the purpose of this invention is to provide a wellhead disassembly and assembly auxiliary device, which can improve the efficiency of wellhead disassembly and assembly operations, improve the convenience of operation, and reduce safety hazards.

[0006] This invention provides a wellhead disassembly and assembly auxiliary device, comprising:

[0007] A control valve is connected to the top of the tubing hanger, and the control valve is used to connect to the tubing;

[0008] A shut-off valve is connected to the top of the oil pipe hanger;

[0009] The external hand pump is connected to the downhole safety valve and the venting valve through the shut-off valve. When the downhole safety valve and the venting valve are in the normally open state, the opening and closing of the downhole safety valve and the venting valve can be controlled by controlling the opening and closing of the shut-off valve.

[0010] Optionally, the control valve includes:

[0011] The upper connector is used to connect to the oil pipe;

[0012] The outer cylinder is connected to the bottom of the upper connector;

[0013] The lower connector is connected to the bottom of the outer cylinder and is used to connect with the oil pipe.

[0014] A plate valve is located at the bottom of the outer cylinder and is used to seal the lower port of the outer cylinder;

[0015] A power unit is disposed inside the outer cylinder, and the power unit is used to control the opening and closing of the plate valve.

[0016] Optionally, the plate valve includes:

[0017] A valve seat is located at the bottom of the outer cylinder;

[0018] The valve plate is hinged to the valve seat;

[0019] A torsion spring is disposed between the valve seat and the valve plate, and the torsion spring is used to control the valve plate to flip and cause the valve plate to block the lower port of the valve seat;

[0020] The power component is used to push the valve plate to flip and open the lower port of the valve seat.

[0021] Optionally, the power component includes:

[0022] The piston is vertically slidably connected inside the outer cylinder;

[0023] A spindle is connected to the bottom of the piston;

[0024] A shear pin, at least one in number, is provided on the upper connector;

[0025] The number of shear grooves is the same as that of the shear pins, and they are formed on the side wall of the piston. The shear pins are inserted into the corresponding shear grooves one by one.

[0026] When the oil pipe is pressurized, the piston can move downward under pressure and break the shear pin. At this time, the mandrel pushes the valve plate to flip, so that the lower port of the outer cylinder opens.

[0027] Optionally, a balance valve is provided on the valve seat. When the mandrel moves downward, the mandrel can control the balance valve to open and connect the lower connector to the outer cylinder.

[0028] Optionally, the power component further includes:

[0029] A forced-opening connector is connected inside the upper connector, and the oil pipe can be connected to the forced-opening connector;

[0030] A forced-open plug is vertically slidably connected to the bottom of the forced-open connector;

[0031] A forced-opening blind hole is provided at the top of the forced-opening plug;

[0032] Multiple through holes are provided, each located on the circumferential sidewall of the forced opening plug, and each of the multiple through holes is connected to the forced opening blind hole.

[0033] A limiting part is provided on the forced opening plug;

[0034] The bottom end of the forced-opening plug is located inside the piston, and the limiting part abuts against the upper end face of the piston, so that the forced-opening plug can push the piston downward under pressure.

[0035] Optionally, the top of the upper connector is threaded with a guide tube, and the oil pipe is threadedly connected to the forced-opening connector after being inserted into the guide tube.

[0036] Optionally, a guide slope is provided at the top of the inner wall of the guide tube.

[0037] Optionally, the upper connector is threadedly connected to the outer cylinder. One of the upper connector and the outer cylinder is detachably connected to a limiting pin, and the other has a limiting groove. After the upper connector and the outer cylinder are threadedly connected, the limiting pin can be inserted into the limiting groove.

[0038] Optionally, the outer cylinder is threadedly connected to the lower connector. One of the outer cylinder and the lower connector is detachably connected with a locking pin, and the other has a locking groove. When the outer cylinder and the lower connector are threadedly connected, the locking pin can be inserted into the locking groove.

[0039] As can be seen from the above technical solution, the wellhead disassembly and assembly auxiliary device provided by the present invention has the following advantages:

[0040] This device uses a shut-off valve to control the opening and closing of the downhole safety valve and venting valve, eliminating the need to reconnect the hydraulic control line. This avoids interference between the blowout preventer (BOP) assembly's operating handle and the hydraulic control line, ensuring smooth pressure testing of the BOP assembly. Furthermore, eliminating the need to reconnect the hydraulic control line reduces the risk of damage to the line during tubing reconnection, minimizing rework and improving wellhead assembly / disassembly efficiency while ensuring operational safety.

[0041] Other features and advantages of the present invention will be set forth in the following description. Attached Figure Description

[0042] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the technical solutions of the present invention, and do not constitute a limitation on the technical solutions of the present invention.

[0043] Figure 1This is a schematic diagram of the structure in which the control valve and the shut-off valve are installed on the oil pipe hanger in an embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram of the structure of the blowout preventer assembly installed on the oil pipe in an embodiment of the present invention;

[0045] Figure 3 This is a cross-sectional view of the control valve in an embodiment of the present invention;

[0046] Figure 4 This is a cross-sectional view of the forced-opening connector and forced-opening plug in an embodiment of the present invention;

[0047] Figure 5 This is a schematic diagram of the structure in which the forced-opening connector and the forced-opening plug are installed in the upper connector in an embodiment of the present invention;

[0048] Figure 6 for Figure 3 An enlarged schematic diagram of region A in the middle.

[0049] Explanation of reference numerals in the attached figures:

[0050] 1. Gate valve; 2. Control valve; 21. Upper connector; 22. Outer cylinder; 23. Lower connector; 3. Plate valve; 31. Valve seat; 32. Valve plate; 4. Power component; 41. Piston; 42. Spindle; 43. Shear pin; 44. Shear groove; 45. Forced opening connector; 46. Forced opening plug; 47. Forced opening blind hole; 48. Through hole; 49. Limiting part; 5. Balance valve; 51. Receiving groove; 52. Balance hole; 53. Balance ball; 54. Elastic component; 6. Guide tube; 7. Guide slope; 8. Limiting pin; 9. Limiting groove; 10. Locking pin; 11. Locking groove; 12. Sealing ring. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be arbitrarily combined with each other.

[0052] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6The illustration shows an embodiment of the present invention, which discloses a wellhead assembly / disassembly auxiliary device, including a shut-off valve 1 and a control valve 2. The control valve 2 is connected to the top of the tubing hanger and is used to connect to the tubing. Simultaneously, the shut-off valve 1 is connected to the top of the tubing hanger, and an external hand pump is connected to a downhole safety valve and a venting valve through the shut-off valve 1. When the downhole safety valve and the venting valve are in the normally open state, the opening and closing of the downhole safety valve and the venting valve can be controlled by controlling the opening and closing of the shut-off valve 1.

[0053] In one embodiment, such as Figure 1 , Figure 2 As shown, after the Christmas tree is removed, control valve 2 (naturally closed) is connected to the tubing hanger. The hand pump is connected to the downhole safety valve and vent valve via shut-off valve 1. Pressure is applied to open the downhole safety valve and vent valve, and then shut-off valve 1 is closed. The downhole safety valve and vent valve are then in the normally open state. At this point, there is no need to reconnect the hydraulic control line. When the blowout preventer (BOP) assembly is installed on the tubing, pressure testing of the BOP assembly can be performed. In this state, the closed control valve 2 acts similarly to the downhole safety valve, effectively controlling any potential overflows in the tubing.

[0054] The wellhead assembly / disassembly auxiliary device in this embodiment controls the opening and closing of the downhole safety valve and venting valve using the shut-off valve 1, eliminating the need to reconnect the hydraulic control line. This avoids interference between the blowout preventer (BOP) assembly's operating handle and the hydraulic control line, ensuring smooth pressure testing of the BOP assembly. Furthermore, eliminating the need to reconnect the hydraulic control line reduces the risk of damage to the line during tubing reconnection, minimizing rework and improving the efficiency and safety of wellhead assembly / disassembly operations.

[0055] In one embodiment, such as Figure 3 , Figure 4 As shown, the control valve 2 includes an upper connector 21, an outer cylinder 22, and a lower connector 23 connected sequentially from top to bottom. The upper connector 21 is used to connect to the oil pipe, and the lower connector 23 is used to hook the oil pipe. A plate valve 3 is provided at the bottom of the outer cylinder 22, and the plate valve 3 is used to block the lower port of the outer cylinder 22. At the same time, a power component 4 is also provided inside the outer cylinder 22, and the power component 4 is used to control the opening and closing of the plate valve 3, so as to realize the control of the opening and closing of the lower port of the outer cylinder 22.

[0056] In special emergency situations where forward and reverse circulation is required to wash and pressure the well or run tools, the control valve 3 can be opened through the power component 4 to create a passage, thereby enabling forward and reverse circulation and meeting the needs of washing and pressure the well or running cutting tools, thus improving practicality.

[0057] In one embodiment, such as Figure 3 , Figure 4As shown, the plate valve 3 includes a valve seat 31, a valve plate 32, and a torsion spring (not shown in the figure). The valve seat 31 is fixedly connected to the bottom of the outer cylinder 22, the valve plate 32 is hinged to the valve seat 31, and the torsion spring is disposed between the valve seat 31 and the valve plate 32. The torsion spring is used to control the valve plate 32 to flip and to block the lower port of the valve seat 31. The power component 4 is used to push the valve plate 32 to flip and to open the lower port of the valve seat 31.

[0058] In one embodiment, such as Figure 3 , Figure 4 As shown, the power component 4 includes a piston 41 vertically slidably disposed within the outer cylinder 22. A spindle 42 is integrally formed at the bottom of the piston 41, and the spindle 42 is used to push the valve plate 32 to flip, thereby opening the lower port of the outer cylinder 22. At least one shear pin 43 is detachably connected to the upper connector 21. The side wall of the piston 41 has the same number of shear grooves 44 as the shear pins 43, and the shear pins 43 are inserted one-to-one into the corresponding shear grooves 44. When the oil pipe is pressurized, the piston 41 can move downwards under pressure, causing the shear pins 43 to break. At this time, the spindle 42 pushes the valve plate 32 to flip, thereby opening the lower port of the outer cylinder 22.

[0059] In this embodiment, there are two shear pins 43. In other embodiments, the number of shear pins 43 may be different, depending on the actual situation, which will not be elaborated here.

[0060] In one embodiment, such as Figure 3 , Figure 4 , Figure 5 As shown, the power component 4 also includes a forced opening connector 45 threadedly connected to the upper connector 21, and the oil pipe can be connected to the forced opening connector 45. Meanwhile, a forced opening plug 46 is vertically slidably connected to the bottom of the forced opening connector 45.

[0061] In one embodiment, such as Figure 3 , Figure 4 , Figure 5 As shown, the top of the forced-opening plug 46 is provided with a forced-opening blind hole 47, and the circumferential sidewall of the forced-opening plug 46 is provided with multiple through holes 48, and the multiple through holes 48 are respectively connected to the forced-opening blind hole 47. A limiting part 49 is provided on the forced-opening plug 46, and the bottom end of the forced-opening plug 46 is located inside the piston 41, and the limiting part 49 abuts against the upper end face of the piston 41, so that the forced-opening plug 46 can push the piston 41 downward under pressure.

[0062] In practice, considering severe wellbore leakage or the poor mud pump operation capacity of some offshore platforms, relying solely on circulation to generate pump pressure is sometimes insufficient to shear the shear pin 43. By setting up a forced opening plug 46 for forced opening of the blind hole 47, under the same gas displacement, the throttling effect of the forced opening plug 46 can cause the forced opening plug 46 to be subjected to a large thrust. This thrust is far greater than the force required by the piston 41 to push the valve plate 32 to flip alone. Therefore, the shear pin 43 can be quickly sheared, thereby ensuring that the lower port of the outer cylinder 22 can be stably opened.

[0063] In this embodiment, the limiting part 49 is a limiting ring integrally formed on the forced opening plug 46, and the limiting ring abuts against the upper end face of the piston 41 to ensure that the forced opening plug 46 can push the piston 41 to move downward stably. Of course, in other embodiments, other structures such as limiting blocks can also be used, as long as they can push the piston 41 to move downward.

[0064] In one embodiment, such as Figure 3 , Figure 6 As shown, a balancing valve 5 is provided on the valve seat 31. The balancing valve 5 includes a receiving groove 51 formed on the valve seat 31, and a balancing hole 52 formed on the valve seat 31 communicating with the receiving groove 51. The receiving groove 51 and the balancing hole 52 can connect the outer cylinder 22 and the lower connector 23. At the same time, a balancing ball 53 is slidably disposed in the receiving groove 51. The inner diameter of the groove opening of the receiving groove 51 gradually decreases to prevent the balancing ball 53 from sliding out of the balancing groove 51, and the balancing ball 53 can block the groove opening of the receiving groove 51. An elastic element 54 is provided in the receiving groove 51 to push the movement of the balancing ball 53. The elastic element 54 can be an elastic ball or a spring, etc.

[0065] When the spindle 42 moves downward, it pushes the balance ball 53 to move and causes the balance ball 53 to enter the receiving groove 51. At this time, the balance ball 53 opens the balance hole 52 and the balance groove 51, thereby connecting the outer cylinder 22 and the lower connector 23, thus balancing the pressure on the upper and lower sides of the valve plate 32. This allows the valve plate 32 to open smoothly even when there is a high pressure difference between the upper and lower sides, improving the stability of use.

[0066] In one embodiment, such as Figure 3 , Figure 5 As shown, the top of the upper connector 21 is threaded with a guide tube 6, and after the oil pipe is inserted into the guide tube 6, it is threaded with the forced opening connector 45. At the same time, the top of the inner wall of the guide tube 6 is integrally formed with a guide slope 7, which makes the top of the guide tube 6 into a trumpet shape, thereby facilitating the reconnection of the oil pipe, ensuring successful docking in one go, playing the role of quick docking, protecting the threads, and improving work efficiency and safety.

[0067] In one embodiment, such as Figure 3 , Figure 5As shown, the upper connector 21 is threadedly connected to the outer cylinder 22. One of the upper connector 21 and the outer cylinder 22 is detachably connected to a limiting pin 8, and the other has a limiting groove 9. After the upper connector 21 and the outer cylinder 22 are threadedly connected, the limiting pin 8 can be inserted into the limiting groove 9 to improve the connection stability between the upper connector 21 and the outer cylinder 22.

[0068] In this embodiment, the bottom end of the upper connector 21 is threaded to the inner side of the outer cylinder 22, meaning the bottom end of the upper connector 21 is located inside the outer cylinder 22. A limiting pin 8 is disposed on the outer cylinder 22, and a limiting groove 9 is formed in the side wall of the upper connector 21. If the top end of the outer cylinder 22 is threaded to the inner side of the upper connector 21, then the limiting pin 8 is disposed on the upper connector 21, and the limiting groove 9 is formed in the side wall of the outer cylinder 22. In this application, the limiting pin 8 is threadedly connected to the upper connector 21 or the outer cylinder 22. In other embodiments, it can also be magnetically fixed or snap-fit ​​fixed, as long as the limiting pin 8 can be detached.

[0069] In one embodiment, such as Figure 3 , Figure 5 As shown, the outer cylinder 22 is threadedly connected to the lower connector 23. One of the outer cylinder 22 and the lower connector 23 is detachably connected with a locking pin 10, and the other has a locking groove 11. When the outer cylinder 22 and the lower connector 23 are threadedly connected, the locking pin 10 can be inserted into the locking groove 11 to improve the connection stability between the outer cylinder 22 and the lower connector 23.

[0070] In this embodiment, the bottom end of the outer cylinder 22 is threaded to the inner side of the lower connector 23, meaning the bottom end of the outer cylinder 22 is located inside the lower connector 23. A locking pin 10 is disposed on the lower connector 23, and a locking groove 11 is formed in the side wall of the outer cylinder 22. If the top end of the lower connector 23 is threaded to the inner side of the outer cylinder 22, then the locking pin 10 is disposed on the outer cylinder 22, and the locking groove 11 is formed in the side wall of the lower connector 23. In this application, the locking pin 10 is threadedly connected to the lower connector 23 or the outer cylinder 22. In other embodiments, it can also be magnetically fixed or snap-fit ​​fixed, as long as the detachable limiting pin 8 can be achieved.

[0071] In one embodiment, such as Figure 3 , Figure 5 As shown, sealing rings 12 are also provided between the upper connector 21 and the outer cylinder 22, and between the outer cylinder 22 and the lower connector 23, to improve the sealing effect and thus improve the stability of the device.

[0072] As can be seen from the above process, this device can ensure the establishment of circulation and cutting channels without reconnecting the hydraulic control line, and without affecting the pressure testing of the blowout preventer (BOP) assembly. The elimination of the need to reconnect the hydraulic control line avoids interference between the BOP assembly's operating handle and the hydraulic control line, thus ensuring the smooth progress of the BOP assembly's pressure testing. Furthermore, eliminating the need to reconnect the hydraulic control line reduces the risk of damage to the hydraulic control line during reconnection of the lift tubing, minimizing rework and improving the efficiency of wellhead assembly and disassembly operations while ensuring operational safety.

[0073] Simultaneously, the device uses the spindle 42 to push the valve plate 32 to rotate, connecting the outer cylinder 22 with the lower connector 23, thus meeting the needs of cyclic operation and the establishment of cutting channels. Furthermore, by incorporating a forced-opening structure, the valve plate 32 can be stably opened, ensuring a stable passage between the outer cylinder 22 and the lower connector 23, thereby improving operational stability.

[0074] It should be noted that, unless otherwise stated, the technical or scientific terms used in this invention should have the ordinary meaning as understood by one of ordinary skill in the art.

[0075] 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 technical features indicated. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A wellhead disassembly and assembly auxiliary device, characterized in that, include: A control valve (2) is connected to the top of the tubing hanger, and the control valve (2) is used to connect to the tubing; The shut-off valve (1) is connected to the top of the oil pipe hanger; The external hand pump is connected to the downhole safety valve and the vent valve through the shut-off valve (1). When the downhole safety valve and the vent valve are in the normally open state, the opening and closing of the downhole safety valve and the vent valve can be controlled by controlling the opening and closing of the shut-off valve (1). The control valve (2) includes: The upper connector (21) is used to connect to the oil pipe; The outer cylinder (22) is connected to the bottom of the upper connector (21); The lower connector (23) is connected to the bottom of the outer cylinder (22), and the lower connector (23) is used to connect with the oil pipe. A plate valve (3) is provided at the bottom of the outer cylinder (22) and is used to block the lower port of the outer cylinder (22); A power component (4) is disposed inside the outer cylinder (22), and the power component (4) is used to control the opening and closing of the plate valve (3); The plate valve (3) includes: A valve seat (31) is disposed at the bottom of the outer cylinder (22); Valve plate (32) is hinged to valve seat (31); A torsion spring is disposed between the valve seat (31) and the valve plate (32), and the torsion spring is used to control the valve plate (32) to flip and cause the valve plate (32) to block the lower port of the valve seat (31); The power component (4) is used to push the valve plate (32) to flip and open the lower port of the valve seat (31); The power component (4) includes: The piston (41) is vertically slidably connected inside the outer cylinder (22); The spindle (42) is connected to the bottom of the piston (41); Shear pin (43), at least one in number, and disposed on the upper connector (21); Shear grooves (44) are the same number as the shear pins (43) and are opened on the side wall of the piston (41). The shear pins (43) are inserted into the corresponding shear grooves (44) one by one. When the oil pipe is pressurized, the piston (41) can move downward under pressure and break the shear pin (43). At this time, the spindle (42) pushes the valve plate (32) to flip so that the lower port of the outer cylinder (22) opens. A balance valve (5) is provided on the valve seat (31). When the spindle (42) moves downward, the spindle (42) can control the balance valve (5) to open and make the lower connector (23) connected to the outer cylinder (22).

2. The wellhead disassembly and assembly auxiliary device according to claim 1, characterized in that, The power component (4) also includes: A forced-opening connector (45) is connected inside the upper connector (21), and the oil pipe can be connected to the forced-opening connector (45); The forced opening plug (46) is vertically slidably connected to the bottom of the forced opening connector (45); A forced blind hole (47) is provided at the top of the forced plug (46); Multiple through holes (48) are provided on the circumferential sidewall of the forced opening plug (46), and the multiple through holes (48) are respectively connected to the forced opening blind hole (47); A limiting part (49) is provided on the forced opening plug (46); The bottom end of the forced opening plug (46) is located inside the piston (41), and the limiting part (49) abuts against the upper end face of the piston (41), so that the forced opening plug (46) can push the piston (41) downward under pressure.

3. The wellhead disassembly and assembly auxiliary device according to claim 2, characterized in that, The top of the upper connector (21) is threaded with a guide tube (6), and the oil pipe is threadedly connected to the forced opening connector (45) after being inserted into the guide tube (6).

4. The wellhead disassembly and assembly auxiliary device according to claim 3, characterized in that, A guide slope (7) is provided at the top of the inner wall of the guide tube (6).

5. The wellhead disassembly and assembly auxiliary device according to claim 1, characterized in that, The upper connector (21) is threadedly connected to the outer cylinder (22). One of the upper connector (21) and the outer cylinder (22) is detachably connected to a limiting pin (8), and the other has a limiting groove (9). When the upper connector (21) and the outer cylinder (22) are threadedly connected, the limiting pin (8) can be inserted into the limiting groove (9).

6. The wellhead disassembly and assembly auxiliary device according to claim 1, characterized in that, The outer cylinder (22) is threadedly connected to the lower connector (23). One of the outer cylinder (22) and the lower connector (23) is detachably connected with a locking pin (10), and the other has a locking groove (11). When the outer cylinder (22) and the lower connector (23) are threadedly connected, the locking pin (10) can be inserted into the locking groove (11).

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