Adjustable pull rod with force value display and overload protection functions

Abstract

The utility model discloses an adjustable pull rod with force value display and overload protection functions, which comprises an upper joint positioned at one end of the adjustable pull rod and capable of being connected to a structure to be detected; the lower joint is positioned at the other end of the adjustable pull rod and is connected to a base body structure; the rod body is connected with the upper joint and the lower joint, and the rod body is configured to be capable of being operated to extend or retract so as to apply an axial force along the axial direction of the rod body to a to-be-detected structure; the upper connector is connected with one end of the rod body through the force measuring device, the force measuring device is constructed to be capable of measuring the axial force and displaying the numerical value and the direction of the axial force, and the rod body can be operated to be elongated or shortened based on the numerical value of the axial force; and the overload protection device is used for connecting the lower joint with the other end of the rod body, and is configured to be invalid when the axial force exceeds a preset threshold value of the overload protection device so as to realize overload protection.

Description

Technical Field

[0001] The utility model relates to an adjustable pull rod, in particular to an adjustable pull rod with force value display and overload protection functions. Background Art

[0002] In the aviation industry, aircraft trim actuators are complex and expensive. If this structure is accidentally damaged, damage assessment and repair operations are extremely complex and costly. For example, according to the maintenance procedures for the ARJ21-700 aircraft, the safety rod locking device of the aircraft's horizontal stabilizer trim actuator must be regularly tested for functionality. During this test, a pull rod is required. By adjusting the extension and contraction of the pull rod, the safety rod of the trim actuator is locked and unlocked to test whether the safety rod is functioning properly. At the same time, to ensure the safety of the fuselage structure and the horizontal stabilizer connection structure at both ends of the pull rod during testing, the tensile (compressive) force of the safety rod is limited to 10,000 Newtons. Therefore, using a pull rod that is simple to operate and highly reliable is the most feasible method.

[0003] To achieve this functionality, a simple internally and externally threaded rod is typically used to extend and retract the tie rod. However, this device lacks force control, can easily damage the aircraft structure, and provides inadequate safety protection. Alternatively, a hydraulic actuator rod can be used to extend and retract the tie rod. However, this requires a hydraulic source, is complex, and carries the risk of hydraulic oil leakage contaminating the aircraft structure. Utility Model Content

[0004] In order to solve the above technical problems, the utility model provides an adjustable pull rod with force value display and overload protection function, characterized in that the adjustable pull rod includes:

[0005] an upper joint, the upper joint being located at one end of the adjustable pull rod and being configured to be coupled to a structure to be inspected;

[0006] a lower joint located at the other end of the adjustable tie rod and configured to be coupled to a base structure;

[0007] a rod body coupled between the upper joint and the lower joint and configured to be operable to extend or shorten so as to apply an axial force along the axial direction of the rod body to the structure to be inspected;

[0008] a force measuring device coupled between the upper joint and one end of the rod body, the force measuring device being configured to measure the axial force and display the magnitude and direction of the axial force; and

[0009] an overload protection device, the overload protection device being connected between the lower joint and the other end of the rod body,

[0010] The rod is configured to be operable to extend or shorten based on the value of the axial force, and the overload protection device is configured to fail when the axial force exceeds a predetermined threshold of the overload protection device, thereby achieving overload protection.

[0011] According to an embodiment of the present utility model, the rod body includes a left-handed threaded rod, a right-handed threaded rod and a sleeve arranged between the left-handed threaded rod and the right-handed threaded rod and threadedly connected to the corresponding ends of the left-handed threaded rod and the right-handed threaded rod respectively, wherein the other end of the left-handed threaded rod opposite to the one end connected to the sleeve is connected to the force measuring device, and the other end of the right-handed threaded rod opposite to the one end connected to the sleeve is connected to the overload protection device, wherein a left-handed thread groove is provided on the inner surface of the end of the sleeve connected to the left-handed threaded rod, and a right-handed thread groove is provided on the inner surface of the other end of the sleeve connected to the right-handed threaded rod, so that the left-handed threaded rod and the right-handed threaded rod can extend or retract the sleeve by rotating the sleeve, thereby extending or shortening the rod body.

[0012] According to one embodiment of the present invention, one end of the left-handed threaded rod is provided with a thin rod extending along the central axis of the left-handed threaded rod, and the thin rod is constructed to have a through recess extending along most of the length of its central axis;

[0013] One end of the right-hand threaded rod is provided with an open chamber extending along the central axis of the right-hand threaded rod and a through hole extending perpendicular to the central axis of the right-hand threaded rod, the chamber being configured to accommodate the thin rod, the through hole accommodating an internally threaded cylindrical pin passing through a through recess of the thin rod to couple the left-hand threaded rod with the right-hand threaded rod; and

[0014] A through hole extending perpendicular to the central axis of the sleeve is provided in the middle of the sleeve, so that the internally threaded cylindrical pin can be inserted into the through hole of the right-handed threaded rod via the through hole of the sleeve.

[0015] According to one embodiment of the present invention, the force measuring device includes a force sensor and a display device communicatively coupled to the force sensor;

[0016] The force sensor is configured to give an alarm when reaching or exceeding a set value, and the display device can display the value and direction of the axial force in real time.

[0017] According to one embodiment of the present invention, the force sensor is connected to the upper joint and the left-hand threaded rod via a cylindrical pin.

[0018] According to one embodiment of the present utility model, the overload protection device includes a shear bolt and a retaining bolt, wherein the shear bolt and the retaining bolt are respectively arranged in corresponding through holes of the right-handed threaded rod to connect the right-handed threaded rod with the lower joint, and the material strength of the shear bolt is less than the material strength of the retaining bolt.

[0019] According to one embodiment of the present invention, the overload protection device further includes a shear bolt bushing, wherein the shear bolt bushing is arranged in a through hole at the other end of the right-handed threaded rod to receive the shear bolt, thereby preventing the shear bolt from directly contacting the right-handed threaded rod.

[0020] According to one embodiment of the present invention, the material strength of the shear bolt bushing exceeds the material strength of the right-hand threaded rod.

[0021] According to one embodiment of the present invention, the overload protection device further comprises a retaining bolt bushing, which is arranged in a through hole at the other end of the right-hand threaded rod to receive the retaining bolt, thereby preventing the retaining bolt from directly contacting the right-hand threaded rod.

[0022] The retaining bolt bushing is made of elastic material, so that when the overload protection device is subjected to the axial force, the shear bolt first bears the axial force, and the shear bolt breaks when the axial force exceeds the predetermined threshold.

[0023] According to one embodiment of the present invention, the sleeve is provided with a plurality of small planes in the middle of the outer portion thereof for operating the sleeve.

[0024] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present utility model.

[0025] The positive and progressive effects of the above-described embodiment of the present invention are that the tie rod not only has the function of adjusting extension and contraction, but also can display the force value. It also provides structural overload protection, where the shear bolt breaks when subjected to a predetermined force. Furthermore, when the shear bolt breaks, the tie rod maintains its ability to maintain the connection between the two structural components that need to remain connected. The tie rod has a simple mechanical structure, is easy to manufacture, has a compact size, is reliable in function, is easy to operate, and requires minimal operator skill. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Non-limiting and non-exhaustive embodiments of the present invention are described with reference to the following drawings, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. The advantages of the present invention will become better understood through the following description and drawings, wherein:

[0027] Figure 1 1 is a perspective view of an adjustable pull rod with force value display and overload protection functions according to an embodiment of the present utility model;

[0028] Figure 2 is a schematic diagram of a force measuring device for an adjustable pull rod according to an embodiment of the present utility model;

[0029] Figure 3 is a schematic diagram of a rod body for an adjustable pull rod according to an embodiment of the present utility model;

[0030] Figure 4 It is a schematic diagram of an overload protection device for an adjustable pull rod according to an embodiment of the present utility model.

[0031] Description of reference numerals:

[0032] 1: Upper connector

[0033] 2: Force measuring device

[0034] 3: Left-hand threaded rod

[0035] 4: Cylindrical pin

[0036] 5: Sleeve

[0037] 6: Right-hand threaded rod

[0038] 7: Internal thread cylindrical pin

[0039] 8: Shear bolt

[0040] 9: Retaining bolt

[0041] 10: Outer bushing

[0042] 11: Retaining bolt bushing

[0043] 12: Shear bolt bushing

[0044] 13: Hexagonal nut

[0045] 14: Spring washer

[0046] 15: Lower connector DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. The following description is for illustrative purposes only and is not intended to limit the present invention. Any other similar situations also fall within the scope of protection of the present invention.

[0048] In the following detailed description, directional terms, such as "left," "right," "up," "down," "front," and "back," are used with reference to the directions depicted in the accompanying drawings. Components of the embodiments of the present invention can be positioned in a variety of different orientations, and the directional terms are used for illustrative purposes only and are not intended to be limiting.

[0049] In the following description, unless otherwise specified or limited, the terms "connected," "coupled," and "fixed" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integrated connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of these terms in this utility model based on specific circumstances.

[0050] To test aircraft horizontal stabilizer trim actuators safely and conveniently, this utility model provides an adjustable pull rod with force display and overload protection. During testing, the pull rod displays the applied axial force and, when the axial force exceeds a predetermined threshold, activates an overload protection device to protect the connected structure.

[0051] like Figure 1 As shown, according to one embodiment of the present utility model, the adjustable pull rod includes an upper joint 1, a force measuring device 2, a left-handed threaded rod 3, a cylindrical pin 4, a sleeve 5, a right-handed threaded rod 6, an internally threaded cylindrical pin 7, a shear bolt 8, a retaining bolt 9, an outer bushing 10, a retaining bolt bushing 11, a shear bolt bushing 12, a hexagonal nut 13, a spring washer 14, and a lower joint 15.

[0052] An upper joint 1 and a lower joint 15 are located at either end of the tie rod, allowing the tie rod to connect the external structure. The structures of the upper joint 1 and the lower joint 15 can vary depending on the type of external structure being connected to meet the connection requirements. For example, in one embodiment, the upper joint 1 includes a cylindrical body and a protrusion extending from the body, and is used to connect to the structure to be inspected. The lower joint 15 has a U-shaped structure and is used to connect to the base structure.

[0053] like Figure 2As shown, force measurement device 2 includes a force sensor positioned between upper connector 1 and left-hand threaded rod 3. The force sensor comprises a cylindrical structure and cylindrical protrusions extending axially away from the cylindrical structure at the centers of its two end faces. The cylindrical protrusion has threads on its side and a through-hole extending perpendicular to its axis for accommodating a cylindrical pin 4. The force sensor can be any sensor capable of measuring the axial force (tension or compression) exerted by the rod.

[0054] The upper joint 1 and the left-handed threaded rod 3 include a recessed portion on their end surfaces near the end of the force sensor for accommodating the cylindrical protrusion of the force sensor, and a through-hole on the side surface near the end of the force sensor for accommodating the cylindrical pin 4. The side surfaces of the recessed portions of the upper joint 1 and the left-handed threaded rod 3 are provided with threads. The upper joint 1, the force sensor, and the left-handed threaded rod 3 are coupled together by threading the cylindrical protrusion of the force sensor into the recessed portions of the upper joint 1 and the left-handed threaded rod 3, respectively, and aligning the through-hole of the cylindrical protrusion of the force sensor with the through-holes of the upper joint 1 and the left-handed threaded rod 3, respectively. The cylindrical pin 4 is then inserted into the through-holes of the upper joint 1, the left-handed threaded rod 3, and the force sensor, respectively.

[0055] The force measurement device 2 also includes a display device communicatively coupled to the force sensor. This display device includes a display capable of displaying the force sensor's readings in real time and distinguishing the direction of the axial force applied by the rod, i.e., the direction of the tension or compression. The display device includes input and output devices and has a warning function. For example, when the tension or compression sensed by the force sensor reaches or exceeds a predetermined threshold, the display device issues a warning. The force sensor and display device are commercially available, for example, the cylindrical tension and compression sensor ZZ210-010L and portable instrument recorder ZZ910 from Shanghai Zhizhan Measurement and Control System Co., Ltd.

[0056] like Figure 3 As shown, the rod body of the adjustable pull rod includes a left-handed threaded rod 3, a right-handed threaded rod 6 and a sleeve 5 arranged between the left-handed threaded rod 3 and the right-handed threaded rod 6 and threadedly connected to the corresponding ends of the left-handed threaded rod 3 and the right-handed threaded rod 6. The left-handed threaded rod 3 includes a main body and a thin rod extending from the main body. The end of the main body near the sleeve 5 has a left-handed thread, which cooperates with the left-handed thread in the sleeve 5. The thin rod extends away from the main body along the axis of the main body from the end face of the end of the main body near the sleeve 5. The length of the thin rod is roughly equal to the length of the main body. Alternatively, the length of the thin rod can also be designed as needed. The diameter of the thin rod is smaller than the diameter of the main body, and the thin rod includes a through recess extending along its axis. The recess is generally elliptical and its length is slightly smaller than the length of the thin rod, that is, the recess extends along most of the length of the thin rod.

[0057] like Figure 3 As shown, the sleeve 5 comprises a hollow tubular structure for accommodating a left-handed threaded rod 3 and a right-handed threaded rod 6. A left-handed thread is provided on the interior of the sleeve 5 near the end of the left-handed threaded rod 3, allowing the left-handed threaded rod 3 to be threadedly coupled to the sleeve 5. A right-handed thread is provided on the interior of the sleeve 5 near the end of the right-handed threaded rod 6, allowing the right-handed threaded rod 6 to be threadedly coupled to the sleeve 5. Thus, one end of the sleeve 5 is threadedly coupled to the left-handed threaded rod 3, and the other end of the sleeve 5 is threadedly coupled to the right-handed threaded rod 3.

[0058] The middle portion of the exterior of the sleeve 5 includes a through hole extending perpendicular to the central axis of the sleeve 5, which is used to accommodate an internally threaded cylindrical pin 7. A plurality of small facets, such as six small facets, are provided near the through hole, which are used to operate the sleeve 5 so that the sleeve 5 rotates around its axis. For example, the operator can use a tool (such as a wrench) or directly operate the sleeve 5 manually to rotate the sleeve 5. Since one end of the sleeve 5 is threadedly connected to the left-handed threaded rod 3 and the other end of the sleeve 5 is threadedly connected to the right-handed threaded rod 6, when the sleeve 5 is rotated, the left-handed threaded rod 3 and the right-handed threaded rod 6 perform linear motion in opposite directions to achieve the extension and contraction of the pull rod. During the extension or contraction of the pull rod, the tension or pressure applied by the pull rod is displayed in real time on the display device of the force measuring device for observation.

[0059] The right-handed threaded rod 6 is provided with right-hand threads on its exterior near the sleeve 5 to engage with the right-handed threads inside the sleeve 5. Also provided at the right-handed threaded rod 6's end near the sleeve 5 is an open chamber extending away from the central axis of the right-handed threaded rod 6 and a through hole extending perpendicular to the central axis of the right-handed threaded rod 6. When the left-handed and right-handed threaded rods 3 and 6 are respectively threadedly coupled to the sleeve 5, the thin rod of the left-handed threaded rod 3 is inserted into the open chamber of the right-handed threaded rod 6, and an internally threaded cylindrical pin 7 is inserted through the external through hole of the sleeve 5 into the recess of the left-handed threaded rod 3 and the through hole of the right-handed threaded rod 6, thereby coupling the left-handed and right-handed threaded rods 3 and 6. This arrangement prevents the pull rod from extending further when the sleeve 5 is rotated to extend the left-handed and right-handed threaded rods 3 and 6 to their maximum lengths, thereby preventing the left-handed and right-handed threaded rods 3 and 6 from detaching from the sleeve 5.

[0060] like Figure 4 As shown, the end of the right-hand threaded rod 6 near the lower joint 15 includes two opposing flat surfaces radially offset from the central axis of the right-hand threaded rod 6 and extending parallel to the central axis. These flat surfaces are provided with two through-holes arranged sequentially along the central axis of the right-hand threaded rod 6 to respectively accommodate the shear bolt bushing 12 and the retaining bolt bushing 11 of the overload protection device. Specifically, the through-hole near the sleeve 5 accommodates the shear bolt bushing 12, while the through-hole away from the sleeve 5 accommodates the retaining bolt bushing 11.

[0061] The right-hand threaded rod 6 is connected to the lower joint 15 through the overload protection device. In addition to the retaining bolt bushing 11 and the shear bolt bushing 12, the overload protection device also includes a shear bolt 8, a retaining bolt 9, an outer bushing 10, a hexagonal nut 13 and a spring washer 14.

[0062] The shear bolt 8 and retaining bolt 9 are universal bolts, respectively disposed within corresponding through-holes in the right-handed threaded rod 6 to connect the right-handed threaded rod 6 to the lower joint 15. The strength of the shear bolt 8 is significantly less than the material strength of the retaining bolt 9. The shank of the shear bolt 8 may be formed with two grooves. Specifically, based on practical needs and through limited shear testing and calculations, grooves may be formed in the shank of the shear bolt 8 to define the double shear breaking value of the shear bolt. The shear bolt 8 prevents excessive tensile (compressive) forces from being transmitted to the connecting structure at both ends of the tie rod, thereby avoiding damage to the connecting structure and providing overload protection.

[0063] To prevent the lower joint 15 of the tie rod from detaching from the right-handed threaded rod 6 when shear bolt 8 breaks, thereby causing the structure connected by the tie rod to lose connection, the retaining bolt 9 is constructed to withstand a shear force far greater than the shear breaking value of the shear bolt 8 without breaking. Therefore, the tie rod can continue to maintain the connection with the structure to be tested, avoiding the connected structure to be tested from losing connection and becoming free, which could lead to uncontrollable risks.

[0064] like Figure 4 As shown, outer bushings 10 are respectively disposed within the four through-holes of lower joint 15, and the material strength of outer bushings 10 exceeds that of lower joint 15. Outer bushings 10 receive shear bolts 8 and retaining bolts 9 and prevent them from directly interacting with lower joint 15, thereby protecting lower joint 15. Outer bushings 10 can be replaced when worn or damaged.

[0065] The retaining bolt bushing 11 is arranged in the through hole of the right-handed threaded rod 6 for accommodating the retaining bolt 9, and receives the retaining bolt 9. The retaining bolt bushing 11 includes an elastic material, for example, silicone rubber. When the retaining bolt bushing 11 is subjected to an axial force along the axial direction of the rod body, the retaining bolt bushing 11 is compressed to ensure that the shear bolt 8 first bears the axial force. If the axial force exceeds the predetermined shear force breaking value, the shear bolt 8 breaks. When the shear bolt 8 breaks, the retaining bolt 9 begins to bear the axial force and prevents the right-handed threaded rod 6 from being separated from the lower joint 15, thereby maintaining the connection effect of the pull rod on the external structure and avoiding accidents. In addition, the retaining bolt bushing 11 can also prevent the retaining bolt 9 from directly contacting the right-handed threaded rod 6, protecting the right-handed threaded rod 6. The retaining bolt bushing 11 can be replaced when worn or damaged.

[0066] Shear bolt bushing 12 is disposed within the through-hole of right-hand threaded rod 6 for accommodating shear bolt 8 and receives shear bolt 8. Shear bolt bushing 12 is made of a material having a strength exceeding that of right-hand threaded rod 6. Shear bolt bushing 12 prevents shear bolt 8 from directly contacting right-hand threaded rod 6, thereby protecting right-hand threaded rod 6. Shear bolt bushing 12 can be replaced when worn or damaged.

[0067] The hexagonal nut 13 and the spring washer 14 are sequentially arranged in cooperation with the outer bushing 10 and accommodate the shanks of the shear bolt 8 and the retaining bolt 9. The hexagonal nut 13 and the spring washer 14 can be of a universal type.

[0068] The adjustable pull rod with force display and overload protection described in this utility model can be used to test the safety lever locking device of the horizontal stabilizer trim actuator of an aircraft. During the test process, the adjustable pull rod includes the following operating steps:

[0069] S1 Select appropriate shear bolts and retaining bolts according to the requirements of the test work;

[0070] S2: Based on the distance between the connecting seat of the fuselage structure and the horizontal stabilizer connecting structure, operate the sleeve to make the length of the tie rod match the above distance;

[0071] S3: Connect the upper joint of the tie rod to the connection seat of the horizontal stabilizer connection structure, and connect the lower joint of the tie rod to the connection seat of the fuselage structure;

[0072] S4 operates the sleeve to extend or shorten the pull rod according to the test requirements;

[0073] S5: Slowly operate the sleeve and observe the tension (compression) value on the display device to prevent the tension (compression) value of the tie rod from exceeding the predetermined threshold. If the tension (compression) value does not exceed the predetermined threshold and the horizontal stabilizer operates abnormally, the operation must be stopped immediately and the fault must be eliminated. If the tension (compression) value does not exceed the predetermined threshold and the horizontal stabilizer operates normally, the test process is completed. If the tension (compression) value exceeds the predetermined threshold, the shear bolt will be sheared and a loud breaking sound will be emitted. At this time, the operation must be stopped immediately and the fault must be eliminated. Then, the shear bolt must be replaced and the test process can be continued.

[0074] After the S6 test process is completed, operate the sleeve to extend or shorten the tie rod so that the tie rod reaches a detachable state without tension (compression);

[0075] S7: Release the connection between the upper and lower joints and the connection bases of the fuselage structure and the horizontal stabilizer connection structure, and remove the tie rods;

[0076] S8 Check the appearance and function of the pull rod, shorten the pull rod to the shortest state, and store it in a packaging box.

[0077] The adjustable pull rod provided by the utility model can also be used in other fields, for example, to safely tighten two mechanical structures in the field of mechanical engineering.

[0078] The adjustable tie rod provided by this utility model has the function of adjusting extension and contraction, can realize force value display, and also has an overload protection function, in which the shear bolt with a set shear breaking value breaks when subjected to a predetermined force. When the shear bolt breaks, the tie rod can continue to connect the structural components. The tie rod has a simple mechanical structure, is easy to manufacture, has a compact appearance, is reliable in function, is easy to operate, and requires low operator skills.

[0079] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of protection of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of protection of the present invention.

Claims

1. An adjustable pull rod with force value display and overload protection function, characterized in that: The adjustable pull rod comprises: an upper joint, the upper joint being located at one end of the adjustable pull rod and being configured to be coupled to a structure to be inspected; a lower joint located at the other end of the adjustable tie rod and configured to be coupled to a base structure; a rod body coupled between the upper joint and the lower joint and configured to be operable to extend or shorten so as to apply an axial force along the axial direction of the rod body to the structure to be inspected; a force measuring device coupled between the upper joint and one end of the rod body, the force measuring device being configured to measure the axial force and display the magnitude and direction of the axial force; and an overload protection device, the overload protection device being connected between the lower joint and the other end of the rod body, The rod is configured to be operable to extend or shorten based on the value of the axial force, and the overload protection device is configured to fail when the axial force exceeds a predetermined threshold of the overload protection device, thereby achieving overload protection.

2. The adjustable pull rod according to claim 1, characterized in that: The rod body includes a left-handed threaded rod, a right-handed threaded rod and a sleeve arranged between the left-handed threaded rod and the right-handed threaded rod and threadedly connected to the corresponding ends of the left-handed threaded rod and the right-handed threaded rod, wherein the other end of the left-handed threaded rod opposite to the one end connected to the sleeve is coupled to the force measuring device, and the other end of the right-handed threaded rod opposite to the one end connected to the sleeve is coupled to the overload protection device, wherein a left-handed thread groove is provided on the inner surface of the end of the sleeve connected to the left-handed threaded rod, and a right-handed thread groove is provided on the inner surface of the other end of the sleeve connected to the right-handed threaded rod, so that the left-handed threaded rod and the right-handed threaded rod can extend or retract the sleeve by rotating the sleeve, thereby extending or shortening the rod body.

3. The adjustable pull rod according to claim 2, characterized in that: One end of the left-handed threaded rod is provided with a thin rod extending along the central axis of the left-handed threaded rod, and the thin rod is configured to have a through recess extending along most of the length of the central axis thereof; One end of the right-hand threaded rod is provided with an open chamber extending along the central axis of the right-hand threaded rod and a through hole extending perpendicular to the central axis of the right-hand threaded rod, the chamber being configured to accommodate the thin rod, the through hole accommodating an internally threaded cylindrical pin passing through a through recess of the thin rod to couple the left-hand threaded rod with the right-hand threaded rod; and A through hole extending perpendicular to the central axis of the sleeve is provided in the middle of the sleeve, so that the internally threaded cylindrical pin can be inserted into the through hole of the right-handed threaded rod via the through hole of the sleeve.

4. The adjustable pull rod according to claim 2, characterized in that: The force measurement device includes a force sensor and a display device communicatively coupled to the force sensor; The force sensor is configured to give an alarm when reaching or exceeding a set value, and the display device can display the value and direction of the axial force in real time.

5. The adjustable pull rod according to claim 4, characterized in that: The force sensor is coupled to the upper joint and the left-hand threaded rod via a cylindrical pin.

6. The adjustable pull rod according to claim 2, characterized in that: The overload protection device includes a shear bolt and a retaining bolt, wherein the shear bolt and the retaining bolt are respectively arranged in corresponding through holes of the right-handed threaded rod to connect the right-handed threaded rod with the lower joint, and the material strength of the shear bolt is less than the material strength of the retaining bolt.

7. The adjustable pull rod according to claim 6, characterized in that: The overload protection device further includes a shear bolt bushing, wherein the shear bolt bushing is disposed in a through hole at the other end of the right-hand threaded rod to receive the shear bolt, thereby preventing the shear bolt from directly contacting the right-hand threaded rod.

8. The adjustable pull rod according to claim 7, characterized in that: The material strength of the shear bolt bushing exceeds the material strength of the right-hand threaded rod.

9. The adjustable pull rod according to claim 7, characterized in that: The overload protection device further includes a retaining bolt bushing, which is disposed in a through hole at the other end of the right-hand threaded rod to receive the retaining bolt, thereby preventing the retaining bolt from directly contacting the right-hand threaded rod. The retaining bolt bushing is made of elastic material, so that when the overload protection device is subjected to the axial force, the shear bolt first bears the axial force, and the shear bolt breaks when the axial force exceeds the predetermined threshold.

10. The adjustable pull rod according to claim 2, characterized in that: The sleeve is provided with a plurality of facets in the middle of its exterior for operating the sleeve.

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