A high-precision downhole laser guidance tool

Abstract

The present invention discloses a high-precision downhole laser guidance tool, which relates to the technical field of drilling equipment, including a transmission system, which is driven by a power system, the transmission system including a shell structure, on which a reference pin is provided, the reference pin radially extends through the shell structure to the interior of the shell structure, and abuts against the outer wall of a rotating shaft structure rotatably arranged in the shell structure, a plurality of correction grooves are provided on the outer wall of the rotating shaft structure, the correction groove has a first contact surface, and a lamp target structure is installed inside the rotating shaft structure, which can generate laser to the ground sensing system, so that ground personnel can observe the relative position of the laser and the reference point on the sensing system; when the transmission system deviates, the power system drives the rotating shaft structure to rotate so that the reference pin enters the correction groove and abuts the first contact surface, and then applies a force opposite to the deviation direction to the rotating shaft structure and drives the rotating shaft structure to rotate until the laser coincides with the reference point, thereby completing the correction of the transmission system and effectively improving the drilling accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling equipment, and in particular to a high-precision downhole laser guidance tool. Background Art

[0002] With the long-term exploitation of shallow oil and gas resources, shallow oil and gas resources are constantly decreasing. To meet the growing energy demand, the depth and difficulty of oil and gas well drilling are constantly increasing. Deep wells, ultra-deep wells, horizontal wells and other complex drilling operations account for an increasing proportion of exploration and development in China and abroad. As these deep wells, ultra-deep wells, horizontal wells and other complex drilling operations increase, the performance requirements of drill pipe are also becoming increasingly higher.

[0003] During the coiled tubing drilling process, due to changes in formation factors (such as changes in formation inclination and hardness, hole reaming, etc.) and operating conditions (such as reverse torque, changes in drilling speed and drilling pressure), the coiled tubing drilling trajectory is prone to deviate from the original design trajectory, resulting in reduced drilling accuracy. Therefore, after the drill pipe deviates, correction is required to improve drilling accuracy, prevent damage to the drill pipe, drilling failure, and avoid losses.

[0004] To this end, we proposed a high-precision downhole laser guidance tool. Summary of the Invention

[0005] In view of the above-mentioned defects or deficiencies in the prior art, it is desired to provide a high-precision downhole laser guidance tool.

[0006] The present invention provides a high-precision downhole laser guidance tool, comprising:

[0007] A transmission system, wherein the transmission system is used for drilling;

[0008] a power system, the power system being used to drive the transmission system;

[0009] The transmission system comprises:

[0010] a shell structure extending in a first direction, with a reference pin provided on an outer wall thereof, the reference pin penetrating the outer wall of the shell structure in a radial direction of the shell structure and extending into the interior of the shell structure;

[0011] a rotating shaft structure, the rotating shaft structure being rotatably disposed within the housing structure, the rotating shaft structure having a plurality of correction grooves uniformly distributed along the circumference on an outer wall thereof, the correction grooves having a first contact surface; and an installation space being disposed within the rotating shaft structure;

[0012] a light target structure, the light target structure being arranged inside the installation space and configured to emit a laser to a sensing system located on the ground to display a relative position of the laser and a reference point on the sensing system;

[0013] When the transmission system is offset, the power system drives the rotating shaft structure to rotate so that the reference pin enters the correction groove and abuts the first contact surface, and then applies a force opposite to the offset direction to the rotating shaft structure and drives the rotating shaft structure to rotate until the laser coincides with the reference point.

[0014] According to the technical solution provided by an embodiment of the present invention, the housing structure includes:

[0015] a first shell, the first shell extending along the first direction, with two ends respectively being a first end and a second end;

[0016] a second shell extending along the first direction, with two ends thereof being a third end and a fourth end respectively;

[0017] The first shell and the second shell are arranged in sequence in the first direction, and the third end is threadedly sleeved on the outer wall of the second end.

[0018] According to the technical solution provided by an embodiment of the present invention, the rotating shaft structure includes:

[0019] a first transmission shaft extending along the first direction, with a fifth end and a sixth end respectively; the fifth end extending outside the first housing for connecting to a drill bit;

[0020] a second transmission shaft, the second transmission shaft extending along the first direction, with two ends thereof being a seventh end and an eighth end respectively;

[0021] A universal shaft is provided between the first transmission shaft and the second transmission shaft, and both ends of the universal shaft are respectively threadedly connected to the sixth end and the seventh end.

[0022] According to the technical solution provided by an embodiment of the present invention, the rotating shaft structure further includes:

[0023] A compression connection joint, one end of which extends into the second shell and is threadedly connected to the eighth end, and the other end of which is used to connect to the power system.

[0024] According to the technical solution provided by an embodiment of the present invention, a through hole arranged along its radial direction is opened on the outer wall of the first shell, the reference pin is arranged inside the through hole, and one end of the reference pin passes through the through hole and extends to the inside of the first shell.

[0025] According to the technical solution provided in an embodiment of the present invention, a plurality of the correcting grooves are evenly arranged circumferentially on the outer wall of the seventh end, and the first contact surface of the correcting groove extends radially along the second transmission shaft;

[0026] The correction groove also includes a second contact surface, whose extension direction forms a preset angle with the extension direction of the first contact surface. The second contact surface is used to guide the reference pin so that the reference pin is away from the correction groove when the second transmission shaft rotates.

[0027] According to the technical solution provided in an embodiment of the present invention, a positioning groove is provided on the second transmission shaft and is connected to the interior thereof. A positioning key is provided in the positioning groove, and a side wall of the positioning key close to the axis of the second transmission shaft protrudes from the inner wall of the second transmission shaft.

[0028] The lamp target structure is arranged inside the second transmission shaft and is interference-fitted with the positioning key.

[0029] The technical solution provided in the embodiment of the present invention further includes a bearing structure;

[0030] The bearing structure comprises:

[0031] a lower TC bearing, the lower TC bearing comprising a first inner ring and a first outer ring, the first inner ring being threadedly connected to the outer wall of the fifth end, and the first outer ring being threadedly connected to the inner wall of the first end;

[0032] Two upper TC bearings, both of which are sleeved on the second transmission shaft and located on the outer walls of the seventh and eighth ends, respectively. The upper TC bearings have a second inner ring and a second outer ring, the second inner ring is connected to the outer wall of the second transmission shaft, and the second outer ring is connected to the inner wall of the second housing;

[0033] The second outer ring of the upper TC bearing corresponding to the seventh end is close to the side wall of the first transmission shaft and abuts against the second end of the first housing;

[0034] A string bearing is sleeved on the second transmission shaft and located between the two upper TC bearings. The string bearing has a third inner ring and a third outer ring. The third inner ring is connected to the outer wall of the second transmission shaft, and the third outer ring is connected to the inner wall of the second shell.

[0035] According to the technical solution provided in an embodiment of the present invention, a gasket is further provided on the outer wall of the eighth end, located on the side of the upper TC bearing corresponding to the eighth end away from the first transmission shaft, and the gasket abuts against the upper TC bearing corresponding to the eighth end and the compression connection joint at both ends in the first direction.

[0036] In summary, the present invention specifically discloses a high-precision downhole laser guidance tool, including a transmission system driven by a power system, the transmission system including a housing structure, on which a reference pin is provided, and the reference pin extends radially through the housing structure to the interior of the housing structure and abuts against the outer wall of a rotating shaft structure rotatably provided inside the housing structure, a plurality of correction grooves are uniformly provided on the outer wall of the rotating shaft structure along the circumferential direction, the correction grooves have a first contact surface, and an installation space is provided inside the rotating shaft structure for installing a lamp target structure, which can emit laser light to a ground sensing system, making it convenient for ground personnel to observe the relative position of the laser light and the reference point on the sensing system;

[0037] When the transmission system deviates, the power system drives the rotating shaft structure to rotate so that the reference pin enters the correction groove and abuts the first contact surface. Then, a force opposite to the deviation direction is applied to the rotating shaft structure to drive the rotating shaft structure to rotate until the laser coincides with the reference point. At this point, the transmission system is corrected, effectively improving the drilling accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0039] Figure 1 This is a front cross-sectional view of a high-precision downhole laser guidance tool.

[0040] Figure 2 An exploded view of a high-precision downhole laser guidance tool.

[0041] Figure 3 Schematic diagram of the driving fluid flow direction.

[0042] Figure 4 Schematic diagram of the laser direction.

[0043] Numbers in the figure: 1. Reference pin; 2. Correction groove; 3. Target structure; 4. First shell; 5. Second shell; 6. First transmission shaft; 7. Second transmission shaft; 8. Universal joint; 9. Compression connection joint; 10. Through hole; 11. Positioning groove; 12. Positioning key; 13. Lower TC bearing; 14. Upper TC bearing; 15. String bearing; 16. Gasket; 17. Wear strip; 18. Flow port. DETAILED DESCRIPTION

[0044] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings.

[0045] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0046] Please refer to Figure 1 and Figure 2 As shown, a high-precision downhole laser guidance tool comprises:

[0047] Transmission system, the transmission system is used for drilling;

[0048] Power system, the power system is used to drive the transmission system;

[0049] The transmission system includes:

[0050] The shell structure extends along the first direction, and a reference pin 1 is provided on its outer wall. The reference pin 1 penetrates the outer wall of the shell structure radially and extends to the interior of the shell structure; the first direction is Figure 1 mid-horizontal direction;

[0051] A rotating shaft structure is rotatably disposed inside the housing structure. A plurality of correcting grooves 2 are uniformly distributed along the circumference of the outer wall of the rotating shaft structure. The correcting grooves 2 have a first contact surface. An installation space is provided inside the rotating shaft structure.

[0052] The target structure 3 is arranged inside the installation space and is used to emit laser light to the sensing system on the ground. Figure 4 , to show the relative position of the laser and the reference point on the sensing system;

[0053] When the transmission system deviates, the power system drives the shaft structure to rotate so that the reference pin 1 enters the correction groove 2 and abuts the first contact surface, and then applies a force opposite to the deviation direction to the shaft structure and drives the shaft structure to rotate until the laser coincides with the reference point.

[0054] The power system is set on the ground and has a driving end, which is connected to the transmission system so that the driving end can drive the transmission system to rotate and realize drilling work;

[0055] There is also an induction system on the ground with a reference point;

[0056] The laser is emitted through the light target structure 3, and a light spot appears on the sensing system. The ground personnel can observe the relative position of the light spot and the reference point;

[0057] The correction groove 2 has a first contact surface and a second contact surface, wherein the first contact surface extends radially along the rotating shaft structure, and the extension direction of the second contact surface forms a preset angle with the radial direction of the rotating shaft structure. When the rotating shaft structure rotates, the reference pin 1 is located at one end inside the shell structure and contacts the outer wall of the rotating shaft structure, and moves along the outer wall of the rotating shaft structure. When the reference pin 1 is located at one end inside the shell structure and contacts the edge of the first contact surface, the reference pin 1 will fall into the correction groove 2, and the rotating shaft structure continues to rotate. The second contact surface can guide the reference pin 1 to keep the reference pin 1 away from the correction groove 2.

[0058] When the power system drives the transmission system for drilling, changes in formation factors (such as changes in formation inclination and hardness, hole reaming) and working conditions (such as counter-torque, changes in drilling speed and weight on bit) will affect the linear drilling of the transmission system, causing the drill pipe to deviate. When the drill pipe deviates, the shaft structure will bend to a certain extent, and the bent part will abut against the inner wall of the wellbore.

[0059] When the drill pipe deviates, the light spot of the laser emitted by the target structure 3 hitting the sensing system will deviate from the reference point. At this time, the drilling operation needs to be stopped.

[0060] The driving end of the power system drives the rotating shaft structure to reverse, and the second contact surface guides the reference pin 1 so that the reference pin 1 enters the correction groove 2 until it contacts the first contact surface. At this time, the rotating shaft structure and the housing structure are considered to be in the reference position, that is, the transmission system is in the reference position.

[0061] By observing the position of the light spot on the sensing system, ground personnel can observe the relative position of the light spot and the reference point, thereby knowing the offset direction of the transmission system;

[0062] The power system applies a force opposite to the offset direction to the shaft structure. This force pushes the shaft structure, causing the bend of the shaft structure to apply pressure to the inner wall of the well. The shaft structure is driven to rotate by the power system, and the shaft structure presses the inner wall of the well to continue drilling. During this process, the light spot will gradually approach the reference point on the sensing system until it coincides with the reference point. At this time, it is considered that the transmission system has been corrected, and drilling work can continue.

[0063] The shell structure includes:

[0064] A first shell 4, the first shell 4 extends along a first direction, and has two ends, respectively, a first end and a second end;

[0065] The second shell 5 extends along the first direction, and has two ends, namely a third end and a fourth end;

[0066] The first shell 4 and the second shell 5 are arranged in sequence in the first direction, and the third end is threadedly sleeved on the outer wall of the second end;

[0067] Furthermore, a through hole 10 is formed on the outer wall of the first shell 4 along its radial direction, and the reference pin 1 is arranged inside the through hole 10, and one end of the reference pin 1 passes through the through hole 10 and extends into the interior of the first shell 4;

[0068] The first shell 4 and the second shell 5 are connected by threads, thereby ensuring the tightness of the connection.

[0069] The shaft structure includes:

[0070] A first transmission shaft 6 extends along the first direction, with a fifth end and a sixth end respectively; the fifth end extends outside the first housing 4 for connecting to a drill bit;

[0071] A second transmission shaft 7, the second transmission shaft 7 extends along the first direction, and has two ends, respectively, a seventh end and an eighth end;

[0072] A universal shaft 8, which is disposed between the first transmission shaft 6 and the second transmission shaft 7, with both ends of the universal shaft 8 being threadedly connected to the sixth end and the seventh end respectively;

[0073] Furthermore, the shaft structure further includes:

[0074] A compression connector 9, one end of which extends into the second housing 5 and is threadedly connected to the eighth end, and the other end of which is used to connect to the power system;

[0075] The driving end of the power system and the clamping connection joint 9 transmit power to the rotating shaft structure. When the transmission system deviates, the driving end applies pressure to the clamping connection joint 9, thereby applying pressure to the rotating shaft structure; the universal joint 8 ensures the continuity of power transmission.

[0076] The second transmission shaft 7 is provided with a positioning groove 11 connected to the interior thereof, and a positioning key 12 is provided in the positioning groove 11. The side wall of the positioning key 12 close to the axis of the second transmission shaft 7 protrudes from the inner wall of the second transmission shaft 7;

[0077] The lamp target structure 3 is arranged inside the second transmission shaft 7 and is interference-fitted with the positioning key 12;

[0078] During assembly, by installing the positioning key 12 in the positioning groove 11, the lamp target structure 3 is then installed into the second transmission shaft 7 from the eighth end of the second transmission shaft 7, so that there is an interference fit between the lamp target structure 3 and the positioning key 12, thereby ensuring that the lamp target structure 3 is installed stably.

[0079] Also includes a bearing structure;

[0080] The bearing structure includes:

[0081] The lower TC bearing 13 includes a first inner ring and a first outer ring, wherein the first inner ring is threadedly connected to the outer wall of the fifth end, and the first outer ring is threadedly connected to the inner wall of the first end;

[0082] Two upper TC bearings 14 are sleeved on the second transmission shaft 7 and are located on the outer walls of the seventh and eighth ends, respectively. The upper TC bearings 14 have a second inner ring and a second outer ring. The second inner ring is connected to the outer wall of the second transmission shaft 7, and the second outer ring is connected to the inner wall of the second housing 5.

[0083] The second outer ring of the upper TC bearing 14 corresponding to the seventh end is close to the side wall of the first transmission shaft 6 and abuts against the second end of the first housing 4;

[0084] The string bearing 15 is sleeved on the second transmission shaft 7 and located between the two upper TC bearings 14. The string bearing 15 has a third inner ring and a third outer ring. The third inner ring is connected to the outer wall of the second transmission shaft 7, and the third outer ring is connected to the inner wall of the second housing 5.

[0085] By setting up a bearing structure, the housing structure and the shaft structure can be stably rotated relative to each other, and at the same time, the housing structure and the shaft structure can be pressurized to avoid excessive bending of the transmission system and causing fracture;

[0086] Further, optionally, a wear strip 17 is provided between the first inner ring and the first outer ring, and a wear strip 17 is provided between the second inner ring and the second outer ring;

[0087] Furthermore, the second end abuts against the upper TC bearing 14 corresponding to the seventh end, and the gasket 16 abuts against the compression connection joint 9, so that the two compression connection joints 9 abut against the string bearing 15 respectively, thereby ensuring the tightness of the structure and stable power transmission.

[0088] There is a gap between the shell structure and the shaft structure for the flow of driving fluid;

[0089] Furthermore, the first transmission shaft 6 is hollow inside, and a flow port 18 communicating with the inside of the first transmission shaft 6 is provided on the side wall thereof for allowing the driving fluid to flow;

[0090] like Figure 3 As shown, the driving hydraulic system inputs, passes through the gap between the second housing 5 and the second transmission shaft 7, then flows through the two upper TC bearings 14 and the string bearing 15, enters the gap between the first housing 4 and the first transmission shaft 6, and enters the first transmission shaft 6 through the flow port 18, and then drives the drill bit to rotate to perform drilling work;

[0091] Optionally, the drive fluid is mud.

[0092] It should be noted that the driving end of the power system is connected to the eighth end; optionally, deep drilling can be performed by connecting multiple sets of transmission systems in sequence.

[0093] Working Principle: During drilling, the power system drives the transmission system to rotate and drill below the ground. As the transmission system continues to penetrate deeper into the ground, it will deviate due to changes in formation factors (such as changes in formation inclination and hardness, hole reaming, etc.) and working conditions (such as counter-torque, changes in drilling speed and drilling pressure). When this deviates, the light spot generated by the laser target structure 3 on the sensing system will shift. Ground personnel can observe the relative position of the light spot and the reference point on the sensing system.

[0094] When the transmission system deviates, the shaft structure bends relative to the drilling direction, and the bend abuts against the inner wall of the wellbore;

[0095] When deviation correction is required, the power system drives the rotating shaft structure to reverse, and the reference pin 1 is guided by the second contact surface to enter the deviation correction groove 2 and abut against the first contact surface. At this time, the rotating shaft structure and the housing structure are considered to be in the reference position. At this time, the ground personnel observe the relative position of the light spot and the reference point to determine the deviation direction of the transmission system;

[0096] Subsequently, the power system applies pressure to the shaft structure, with the pressure direction being opposite to the offset direction, thereby enabling the curved part of the shaft structure to squeeze the inner wall of the wellbore. The power system then drives the shaft structure to rotate, thereby enabling the shaft structure to continuously approach the initial drilling direction. Ground personnel observe that the light spot gradually approaches the reference point until it coincides with the reference point. At this point, it is believed that the transmission system has returned to the initial drilling direction, completing the correction of the transmission system, and then drilling work can continue, effectively improving the drilling accuracy.

[0097] The above description is merely a preferred embodiment of the present invention and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of the invention is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the inventive concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions disclosed in the present invention.

Claims

1. A high-precision downhole laser guidance tool, characterized in that: include: A transmission system, wherein the transmission system is used for drilling; a power system, the power system being used to drive the transmission system; The transmission system comprises: A shell structure, the shell structure extending in a first direction, a reference pin (1) being provided on an outer wall thereof, the reference pin (1) penetrating the outer wall of the shell structure in a radial direction of the shell structure and extending into the interior of the shell structure; A rotating shaft structure, the rotating shaft structure being rotatably arranged inside the shell structure, a plurality of correction grooves (2) uniformly distributed along its circumference are arranged on the outer wall of the rotating shaft structure, the correction grooves (2) having a first contact surface; and an installation space is arranged inside the rotating shaft structure; A light target structure (3), the light target structure (3) being arranged inside the installation space and used for emitting laser light to a sensing system located on the ground to display the relative position of the laser light and a reference point on the sensing system; When the transmission system deviates, the power system drives the rotating shaft structure to rotate so that the reference pin (1) enters the deviation correction groove (2) and abuts the first contact surface, and then applies a force opposite to the deviation direction to the rotating shaft structure and drives the rotating shaft structure to rotate until the laser coincides with the reference point.

2. A high-precision downhole laser guidance tool according to claim 1, characterized in that: The housing structure comprises: A first shell (4), the first shell (4) extending along the first direction, with two ends thereof respectively being a first end and a second end; A second shell (5), the second shell (5) extending along the first direction, with two ends thereof being a third end and a fourth end respectively; The first shell (4) and the second shell (5) are arranged in sequence in the first direction, and the third end is threadedly sleeved on the outer wall of the second end.

3. A high-precision downhole laser guidance tool according to claim 2, characterized in that: The rotating shaft structure comprises: A first transmission shaft (6), the first transmission shaft (6) extending along the first direction, with two ends respectively being a fifth end and a sixth end; the fifth end extending outside the first housing (4) and being used for connecting to a drill bit; a second transmission shaft (7), the second transmission shaft (7) extending along the first direction, with two ends thereof being a seventh end and an eighth end respectively; A universal shaft (8), the universal shaft (8) being arranged between the first transmission shaft (6) and the second transmission shaft (7), and the two ends of the universal shaft (8) being threadedly connected to the sixth end and the seventh end respectively.

4. A high-precision downhole laser guidance tool according to claim 3, characterized in that: The rotating shaft structure further includes: A compression connection joint (9), one end of the compression connection joint (9) extends into the second housing (5) and is threadedly connected to the eighth end, and the other end of the compression connection joint (9) is used to connect to the power system.

5. A high-precision downhole laser guidance tool according to claim 2, characterized in that: A through hole (10) arranged along the radial direction is provided on the outer wall of the first shell (4), the reference pin (1) is arranged inside the through hole (10), and one end of the reference pin (1) passes through the through hole (10) and extends into the interior of the first shell (4).

6. A high-precision downhole laser guidance tool according to claim 3, characterized in that: A plurality of the deviation-correcting grooves (2) are evenly arranged circumferentially on the outer wall of the seventh end, and the first contact surface of the deviation-correcting groove (2) extends radially along the second transmission shaft (7); The correction groove (2) further comprises a second contact surface, the extension direction of which forms a preset angle with the extension direction of the first contact surface, and the second contact surface is used to guide the reference pin (1) when the second transmission shaft (7) rotates so that the reference pin (1) is away from the correction groove (2).

7. A high-precision downhole laser guidance tool according to claim 3, characterized in that: The second transmission shaft (7) is provided with a positioning groove (11) communicating with the interior thereof, a positioning key (12) is provided in the positioning groove (11), and the side wall of the positioning key (12) close to the axis of the second transmission shaft (7) protrudes from the inner wall of the second transmission shaft (7); The lamp target structure (3) is arranged inside the second transmission shaft (7) and is interference-fitted with the positioning key (12).

8. The high-precision downhole laser guidance tool according to claim 4, characterized in that: Also includes a bearing structure; The bearing structure comprises: A lower TC bearing (13), the lower TC bearing (13) comprising a first inner ring and a first outer ring, the first inner ring being threadedly connected to the outer wall of the fifth end, and the first outer ring being threadedly connected to the inner wall of the first end; Two upper TC bearings (14), both of which are sleeved on the second transmission shaft (7) and located on the outer walls of the seventh end and the eighth end, respectively, and the upper TC bearings (14) have a second inner ring and a second outer ring, the second inner ring is connected to the outer wall of the second transmission shaft (7), and the second outer ring is connected to the inner wall of the second housing (5); The second outer ring of the upper TC bearing (14) corresponding to the seventh end is close to the side wall of the first transmission shaft (6) and abuts against the second end of the first housing (4); A string bearing (15), the string bearing (15) is sleeved on the second transmission shaft (7) and located between the two upper TC bearings (14), the string bearing (15) having a third inner ring and a third outer ring, the third inner ring being connected to the outer wall of the second transmission shaft (7), and the third outer ring being connected to the inner wall of the second housing (5).

9. A high-precision downhole laser guidance tool according to claim 8, characterized in that: A gasket (16) is also sleeved on the outer wall of the eighth end, located on a side of the upper TC bearing (14) corresponding to the eighth end and away from the first transmission shaft (6), and the gasket (16) abuts against the upper TC bearing (14) corresponding to the eighth end and the compression connection joint (9) at both ends in the first direction.

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