High-precision control method applicable to space linkage antenna array deployment and recovery mechanism

Abstract

This invention provides a high-precision control method for space-link antenna array deployment and retraction mechanisms, relating to the field of radar antenna array erection technology. The high-precision control method counteracts gravity-induced deformation by employing unidirectional internal stress pre-deformation design on the deployment and retraction mechanism, reducing gravity-induced deformation during deployment and retraction. This results in symmetrical deformation of the scissor arms along the centerline, achieving optimal overall flatness at the frame mounting position, and realizing a high-precision, repeatable configuration for the deployment and retraction mechanism. Furthermore, the control precision of the deployment and retraction mechanism is further ensured by using a synchronous linkage mechanism between the upper and lower scissor arms, multiple synchronously operating drive cylinders on the scissor arms, a hinge shaft at the hinge point of the scissor arms combined with two sets of back-to-back, backlash-free conical roller bearings to achieve stable hinge connection between the outer and inner connecting rods, and a frame hinge seat connecting the frame at the hinge shaft end of the scissor arms.

Description

Technical Field

[0001] This invention relates to the field of radar antenna array erection technology, and specifically to a high-precision control method applicable to space linkage antenna array deployment and retraction mechanisms. Background Technology

[0002] As radar antenna array apertures increase, the survivability and operational stealth of radars are urgent requirements in modern warfare. Space-linked antenna array deployment and dismantling systems have extremely high mobility and can realize the mobile deployment and dismantling of highly integrated large-aperture antenna arrays, making them an excellent choice for the deployment and dismantling of low-frequency large-aperture radar arrays.

[0003] However, spatial linkage mechanisms have many hinge points and are extremely flexible. How to control array deformation and ensure the accuracy of the antenna array while ensuring the erection and dismantling of large-aperture antenna arrays is a major engineering problem. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a high-precision control method applicable to space linkage antenna array deployment and recovery mechanisms, solving the problem of poor control accuracy in space linkage antenna array deployment and recovery mechanisms.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A high-precision control method applicable to space linkage antenna array deployment and retraction mechanisms, the high-precision control method comprising:

[0007] The first of the lower scissor arms Unit arm unfolded length relatively The lengthening process generates internal stress in the deployed state of the scissor arm, causing it to tilt upwards at an angle of [value missing]. The deflection satisfies:

[0008]

[0009] in, This represents the unit arm extension length of the upper scissor arm;

[0010] Its value is set to ;

[0011] For the upper scissor arm The deflection angle of the first unit arm relative to the first unit arm.

[0012] Preferably, the deployment and recovery mechanism includes: a support, a scissor arm, and a column frame;

[0013] The support is equipped with a scissor arm that extends and retracts in the horizontal direction;

[0014] The scissor arm is equipped with multiple columns of frames arranged along the extension and retraction direction, each column of frames extending vertically.

[0015] The scissor arm includes: an upper scissor arm and a lower scissor arm;

[0016] The upper part of the column frame is connected to the upper scissor arm, and the lower part is connected to the lower scissor arm.

[0017] Preferably, in the deployed state of the upper scissor arm, its first... Vertical displacement at the end of the unit arm for:

[0018]

[0019]

[0020] in, The angle of deflection of the adjacent unit arm of the upper scissor arm at the corresponding hinge point.

[0021] Preferably, the high-precision control method further includes:

[0022] A synchronous linkage mechanism is installed between the upper scissor arm and the lower scissor arm;

[0023] The synchronous linkage mechanism includes: a fixed hinge point, a first link, a second link, and a third link;

[0024] The fixed hinge point is set on the support, the midpoint of the first link is hinged to the fixed hinge point, and the two ends of the first link are respectively hinged to the head ends of the second link and the third link.

[0025] The end of the second link is hinged to the upper scissor arm, and the end of the third link is hinged to the lower scissor arm. The second link and the third link are of equal length.

[0026] Preferably, the upper connecting rod at the head end of the upper scissor arm is hinged to the support, the lower connecting rod at the head end of the upper scissor arm is hinged to the first slider, the first slider is slidably connected to the support, and the end of the second connecting rod is hinged to the first slider.

[0027] The lower connecting rod at the head end of the lower scissor arm is hinged to the support, the upper connecting rod at the head end of the lower scissor arm is hinged to the second slider, the second slider is slidably connected to the support, and the end of the third connecting rod is hinged to the second slider.

[0028] The support is provided with a limit baffle to limit the movement limit positions of the first slider and the second slider;

[0029] Pins are provided between the support and the first and second sliders to fix the first and second sliders to the support after the scissor arm is extended or retracted.

[0030] Preferably, the high-precision control method further includes:

[0031] Multiple synchronously operating drive cylinders are installed on the scissor arm, and the extension direction of all drive cylinders is parallel to the extension and retraction direction of the scissor arm.

[0032] The drive cylinder self-locks after being deployed, enabling rigid positioning of the scissor arm along the deployment direction.

[0033] Preferably, the high-precision control method further includes:

[0034] At the hinge point of the scissor arm, a hinge shaft is used in conjunction with two sets of back-to-back tapered roller bearings to stably hinge the outer connecting rod and the inner connecting rod.

[0035] The outer connecting rod has an outer hinge hole, and the inner connecting rod has an inner hinge hole.

[0036] The head end of the hinge shaft is interference-fitted with the outer hinge hole, and the end end is connected to the inner hinge hole bearing through two sets of back-to-back tapered roller bearings, thereby realizing the hinge connection between the outer connecting rod and the inner connecting rod.

[0037] The hinge shaft is provided with a first stud at its end. Two sets of tapered roller bearings are installed back to back in the inner hinge hole. The end of the hinge shaft is connected to two first round nuts by threads through the two sets of tapered roller bearings. The first round nuts are tightened with torque to eliminate the gaps and press the two sets of tapered roller bearings together. A first anti-loosening washer is provided between the two first round nuts.

[0038] Preferably, the inner end of the inner hinge hole is fitted with a cap to prevent sand and foreign objects from entering.

[0039] Preferably, the inner connecting rod is provided with a grease inlet communicating with the inner hinge hole for periodically injecting grease into the tapered roller bearing.

[0040] Preferably, the high-precision control method further includes:

[0041] The scissor arm is connected to the column frame via a column frame hinge seat at the hinge head end;

[0042] The frame hinge seat includes: a sliding bearing, a hinge seat, a retaining ring, a second anti-loosening washer, and a second round nut;

[0043] The hinge seat is connected to the hinge shaft bearing via a sliding bearing, and the frame is fixedly connected to the hinge seat;

[0044] One end of the sliding bearing is limited by the shoulder of the hinge shaft, and the other end is limited by the retaining ring;

[0045] The hinge head is provided with a second stud, which passes through the retaining ring and the second anti-loosening washer in sequence and is then threadedly connected to the second round nut.

[0046] This invention provides a high-precision control method suitable for space-linked antenna array deployment and reception mechanisms. Compared with existing technologies, it has the following advantages:

[0047] In this invention, the high-precision control method offsets the deformation caused by gravity by designing a unidirectional internal stress pre-deformation for the deployment and retrieval mechanism, reducing the deformation caused by gravity during the deployment and retrieval process. This results in the scissor arms exhibiting symmetrical deformation along the centerline, and the overall flatness at the frame installation position reaches the optimal state, achieving a high-precision repeatable configuration for the deployment and retrieval mechanism. Furthermore, the control precision of the deployment and retrieval mechanism is further ensured by setting a synchronous linkage mechanism between the upper and lower scissor arms, setting multiple synchronously operating drive cylinders on the scissor arms, using a hinge shaft at the hinge point of the scissor arms in conjunction with two sets of back-to-back, backlash-free tapered roller bearings to achieve stable hinge connection between the outer and inner connecting rods, and connecting the frame frame to the hinge shaft end of the scissor arms via a frame frame hinge seat. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the unfolding and retracting mechanism in an embodiment of the present invention.

[0050] Figure 2 This is a schematic diagram of a modified unfolding and retracting mechanism in an embodiment of the present invention.

[0051] Figure 3 This is a schematic diagram illustrating the structural principle of the synchronous linkage mechanism in an embodiment of the present invention.

[0052] Figure 4 This is a schematic diagram of the hinge of the scissor arm in an embodiment of the present invention.

[0053] Figure 5 for Figure 4 Enlarged view of point A in the middle.

[0054] Figure 6 for Figure 4 Enlarged view of point B in the middle.

[0055] The reference numerals in the figure are set as follows: support 10, column frame 20, upper scissor arm 30, first slider 31, lower scissor arm 40, second slider 41, fixed hinge point 50, first connecting rod 51, second connecting rod 52, third connecting rod 53, drive cylinder 60, hinge shaft 70, tapered roller bearing 71, outer connecting rod 72, inner connecting rod 73, first round nut 74, first anti-loosening washer 75, cover 76, grease inlet 77, column frame hinge seat 80, sliding bearing 81, hinge seat 82, retaining ring 83, second anti-loosening washer 84, second round nut 85. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] This application provides a high-precision control method suitable for space linkage antenna array deployment and recovery mechanisms, thus solving the problem of poor control accuracy in space linkage antenna array deployment and recovery mechanisms.

[0058] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0059] Example:

[0060] This invention provides a high-precision control method applicable to space linkage antenna array deployment and recovery mechanisms, the high-precision control method comprising:

[0061] By implementing a unidirectional internal stress pre-deformation design for the deployment and retraction mechanism, the deformation caused by gravity is offset, thereby reducing the deformation of the deployment and retraction mechanism caused by gravity during the deployment and retraction process and achieving a high-precision repeatable configuration for the deployment and retraction mechanism.

[0062] like Figure 1 As shown, the deployment and retraction mechanism includes: a support 10, a scissor arm, and a column frame 20;

[0063] The support 10 is equipped with a scissor arm that extends and retracts in the horizontal direction.

[0064] The scissor arm is equipped with multiple column frames 20 arranged along the extension and retraction direction. Each column frame 20 extends vertically, and the antenna array is mounted on the column frame 20.

[0065] The scissor arms include: an upper scissor arm 30 and a lower scissor arm 40;

[0066] The upper part of the column frame 20 is connected to the upper scissor arm 30, and the lower part is connected to the lower scissor arm 40.

[0067] like Figure 2 As shown, in the deployed state, the deformation of the scissor arm is mainly caused by the angular deflection at the hinge point. The scissor arm consists of multiple unit arms between adjacent hinge points. In the deployed state, the upper scissor arm 30... Vertical displacement at the end of the unit arm for:

[0068]

[0069]

[0070] in, The unit arm extension length between two adjacent hinge points of the upper scissor arm 30;

[0071] The angle of deflection of the adjacent unit arm of the upper scissor arm 30 at the corresponding hinge point.

[0072] The unidirectional internal stress pre-deformation includes:

[0073] The lower scissor arm 40 Unit arm unfolded length relatively The lengthening process generates internal stress in the deployed state of the scissor arm, causing it to tilt upwards at an angle of [value missing]. The deflection satisfies:

[0074]

[0075] in, Its value is set to ;

[0076] This results in the scissor arm exhibiting symmetrical deformation along the centerline, and the overall flatness at the mounting position of the frame 40 reaches its optimal state.

[0077] like Figure 1 , Figure 3 As shown, the high-precision control method further includes:

[0078] A synchronous linkage mechanism is set between the upper scissor arm 30 and the lower scissor arm 40 to improve the synchronization rate of the extension and retraction of the upper scissor arm 30 and the lower scissor arm 40.

[0079] The synchronous linkage mechanism includes: a fixed hinge point 50, a first link 51, a second link 52, and a third link 53;

[0080] The fixed hinge point 50 is set on the support 10. The midpoint of the first connecting rod 51 is hinged to the fixed hinge point 50, and the two ends of the first connecting rod 51 are respectively hinged to the head ends of the second connecting rod 52 and the third connecting rod 53.

[0081] The end of the second link 52 is hinged to the upper scissor arm 30, and the end of the third link 53 is hinged to the lower scissor arm 40. The second link 52 and the third link 53 are of equal length.

[0082] like Figure 1 , Figure 3 As shown, the upper connecting rod at the head end of the upper scissor arm 30 is hinged to the support 10, the lower connecting rod at the head end of the upper scissor arm 30 is hinged to the first slider 31, the first slider 31 is slidably connected to the support 10, and the end of the second connecting rod 52 is hinged to the first slider 31.

[0083] The lower connecting rod at the head end of the lower scissor arm 40 is hinged to the support 10, the upper connecting rod at the head end of the lower scissor arm 40 is hinged to the second slider 41, the second slider 41 is slidably connected to the support 10, and the end of the third connecting rod 53 is hinged to the second slider 41.

[0084] The support 10 is provided with a limit baffle to limit the movement limit positions of the first slider 31 and the second slider 41;

[0085] Pins are provided between the support 10 and the first slider 31 and the second slider 41 to fix the first slider 31, the second slider 41 and the support 10 after the scissor arm is extended or retracted.

[0086] like Figure 1 As shown, the high-precision control method further includes:

[0087] Multiple synchronously operating drive cylinders 60 are installed on the scissor arm, and the extension direction of all drive cylinders 60 is parallel to the extension and retraction direction of the scissor arm.

[0088] The drive cylinder 60 self-locks after being deployed, enabling rigid positioning of the scissor arm along the deployment direction.

[0089] like Figure 4 , Figure 5 As shown, the high-precision control method further includes:

[0090] The hinge point of the scissor arm uses a hinge shaft 70 in conjunction with two sets of back-to-back tapered roller bearings 71 to achieve a stable hinge connection between the outer connecting rod 72 and the inner connecting rod 73, thereby improving the overall rigidity of the scissor arm and reducing the deformation of the extension and retraction mechanism.

[0091] The outer connecting rod 72 has an outer hinge hole, and the inner connecting rod 73 has an inner hinge hole.

[0092] The head end of the hinge shaft 70 is interference-fitted with the outer hinge hole, and the end end is connected to the inner hinge hole bearing through two sets of back-to-back tapered roller bearings 71, thereby realizing the hinge connection between the outer connecting rod 72 and the inner connecting rod 73.

[0093] The hinge shaft 70 is provided with a first stud at its end. Two sets of tapered roller bearings 71 are installed back-to-back in the inner hinge hole. The end of the hinge shaft 70 is threadedly connected to two first round nuts 74 after passing through the two sets of tapered roller bearings 71. The first round nuts 74 are tightened with torque to eliminate gaps and press the two sets of tapered roller bearings 71 tightly. A first anti-loosening washer 75 is provided between the two first round nuts 74 to prevent the first round nuts 74 from loosening.

[0094] A cap 76 is installed at the inner end of the inner hinge hole to prevent sand and foreign objects from entering.

[0095] The inner connecting rod 73 is provided with a grease inlet 77 that connects to the inner hinge hole, which is used to periodically inject grease into the tapered roller bearing 71 to ensure smooth rotation.

[0096] like Figure 4 , Figure 6 As shown, the high-precision control method further includes:

[0097] The scissor arm hinge pin 70 is connected to the column frame 20 through the column frame hinge seat 80, so that even if the upper scissor arm 30 and the lower scissor arm 40 are out of sync during the extension and retraction process, the column frame 20 can still maintain axial force, avoiding radial stress in the column frame 20 that could lead to deformation or even breakage.

[0098] The column frame hinge seat 80 includes: a sliding bearing 81, a hinge seat 82, a retaining ring 83, a second anti-loosening washer 84, and a second round nut 85;

[0099] The hinge seat 82 is connected to the hinge shaft 70 bearing through the sliding bearing 81, and the frame 20 is fixedly connected to the hinge seat 82;

[0100] One end of the sliding bearing 81 is limited by the shoulder of the hinge shaft 70, and the other end is limited by the retaining ring 83;

[0101] The hinge shaft 70 is provided with a second stud at its head end. The second stud passes through the retaining ring 83 and the second anti-loosening washer 84 in sequence and is then threadedly connected to the second round nut 85.

[0102] In summary, compared with the prior art, the present invention has the following beneficial effects:

[0103] 1. In this embodiment of the invention, the high-precision control method offsets the deformation caused by gravity by performing unidirectional internal stress pre-deformation design on the deployment and retraction mechanism, reduces the deformation caused by gravity in the deployment and retraction process, so that the scissor arm exhibits symmetrical deformation along the centerline, and the overall flatness at the installation position of the column frame 40 reaches the optimal state, thereby realizing a high-precision repeatable configuration of the deployment and retraction mechanism.

[0104] 2. In this embodiment of the invention, the high-precision control method improves the synchronization rate of the extension and retraction of the upper scissor arm 30 and the lower scissor arm 40 by setting a synchronous linkage mechanism between the upper scissor arm 30 and the lower scissor arm 40, thereby further ensuring the control precision of the extension and retraction mechanism.

[0105] 3. In this embodiment of the invention, the high-precision control method sets multiple synchronously operating drive cylinders 60 on the scissor arm. After the drive cylinders 60 are deployed into position, they self-lock, which can achieve rigid positioning of the scissor arm along the deployment direction, further ensuring the control accuracy of the deployment and retraction mechanism.

[0106] 4. In this embodiment of the invention, the high-precision control method achieves stable hinge connection between the outer connecting rod 72 and the inner connecting rod 73 by using a hinge shaft 70 in conjunction with two sets of back-to-back tapered roller bearings 71 installed at the hinge point of the scissor arm, thereby improving the overall rigidity of the scissor arm, reducing the deformation of the unfolding mechanism, and further ensuring the control accuracy of the unfolding mechanism.

[0107] 5. In this embodiment of the invention, the high-precision control method connects the column frame 20 to the head end of the hinge shaft 70 of the scissor arm through the column frame hinge seat 80, so that even if the upper scissor arm 30 and the lower scissor arm 40 are out of sync during the extension and retraction process, the column frame 20 can still maintain axial force, avoiding radial stress in the column frame 20 that could lead to deformation or even breakage, thus further ensuring the control precision of the extension and retraction mechanism.

[0108] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0109] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-precision control method for a space-link antenna array deployment and retraction mechanism, characterized in that, The deployment and retraction mechanism includes: a support (10), a scissor arm, and a column frame (20). The support (10) is equipped with a scissor arm that extends and retracts in the horizontal direction; The scissor arm is equipped with multiple column frames (20) arranged along the extension and retraction direction, and each column frame (20) extends vertically. The scissor arms include: an upper scissor arm (30) and a lower scissor arm (40). The upper part of the column frame (20) is connected to the upper scissor arm (30), and the lower part is connected to the lower scissor arm (40); The high-precision control method includes: The first of the lower scissor arm (40) Unit arm unfolded length relatively The lengthening process generates internal stress in the deployed state of the scissor arm, causing it to tilt upwards at an angle of [value missing]. The deflection satisfies: in, The unit arm unfolded length of the upper scissor arm (30); Its value is set to ; For the upper scissor arm (30) The deflection angle of the first unit arm relative to the first unit arm; The angle of deflection of the adjacent unit arm of the upper scissor arm (30) at the corresponding hinge point.

2. The high-precision control method for space linkage antenna array deployment and retraction mechanism as described in claim 1, characterized in that, The high-precision control method also includes: A synchronous linkage mechanism is provided between the upper scissor arm (30) and the lower scissor arm (40); The synchronous linkage mechanism includes: a fixed hinge point (50), a first link (51), a second link (52), and a third link (53); The fixed hinge point (50) is set on the support (10), the midpoint of the first link (51) is hinged to the fixed hinge point (50), and the two ends of the first link (51) are respectively hinged to the head ends of the second link (52) and the third link (53). The end of the second link (52) is hinged to the upper scissor arm (30), and the end of the third link (53) is hinged to the lower scissor arm (40). The second link (52) and the third link (53) are of equal length.

3. The high-precision control method for space linkage antenna array deployment and retraction mechanisms as described in claim 2, characterized in that, The upper connecting rod at the head end of the upper scissor arm (30) is hinged to the support (10), the lower connecting rod at the head end of the upper scissor arm (30) is hinged to the first slider (31), the first slider (31) is slidably connected to the support (10), and the end of the second connecting rod (52) is hinged to the first slider (31). The lower connecting rod at the head end of the lower scissor arm (40) is hinged to the support (10), the upper connecting rod at the head end of the lower scissor arm (40) is hinged to the second slider (41), the second slider (41) is slidably connected to the support (10), and the end of the third connecting rod (53) is hinged to the second slider (41). The support (10) is provided with a limit baffle to limit the movement limit positions of the first slider (31) and the second slider (41); Pins are provided between the support (10) and the first slider (31) and the second slider (41) to fix the first slider (31), the second slider (41) and the support (10) after the scissor arm is extended or retracted.

4. The high-precision control method for space linkage antenna array deployment and retraction mechanisms as described in claim 1, characterized in that, The high-precision control method also includes: Multiple synchronously operating drive cylinders (60) are installed on the scissor arm, and the extension direction of all drive cylinders (60) is parallel to the extension and retraction direction of the scissor arm. The drive cylinder (60) self-locks after being deployed, which enables rigid positioning of the scissor arm along the deployment direction.

5. The high-precision control method for space linkage antenna array deployment and retraction mechanism as described in claim 1, characterized in that, The high-precision control method also includes: At the hinge point of the scissor arm, a hinge shaft (70) is used in conjunction with two sets of back-to-back tapered roller bearings (71) to stably hinge the outer connecting rod (72) and the inner connecting rod (73). The outer connecting rod (72) has an outer hinge hole, and the inner connecting rod (73) has an inner hinge hole; The head end of the hinge shaft (70) is interference-fitted with the outer hinge hole, and the end is connected to the inner hinge hole bearing through two sets of back-to-back tapered roller bearings (71), thereby realizing the hinge connection between the outer connecting rod (72) and the inner connecting rod (73). The hinge shaft (70) is provided with a first stud at its end. Two sets of tapered roller bearings (71) are installed back to back in the inner hinge hole. The end of the hinge shaft (70) is connected to two first round nuts (74) by thread through the two sets of tapered roller bearings (71). The first round nuts (74) are tightened with torque to eliminate gaps and press the two sets of tapered roller bearings (71) together. A first anti-loosening washer (75) is provided between the two first round nuts (74).

6. The high-precision control method for space linkage antenna array deployment and retraction mechanism as described in claim 5, characterized in that, A cap (76) is installed at the inner end of the inner hinge hole to prevent sand and foreign objects from entering.

7. The high-precision control method for space linkage antenna array deployment and retraction mechanism as described in claim 5, characterized in that, The inner connecting rod (73) is provided with a grease inlet (77) that connects to the inner hinge hole, for periodically injecting grease into the position of the tapered roller bearing (71).

8. The high-precision control method for space linkage antenna array deployment and retraction mechanism as described in claim 5, characterized in that, The high-precision control method also includes: The scissor arm's hinge pin (70) is connected to the column frame (20) via the column frame hinge seat (80). The column frame hinge seat (80) includes: a sliding bearing (81), a hinge seat (82), a retaining ring (83), a second anti-loosening washer (84), and a second round nut (85); The hinge seat (82) is connected to the hinge shaft (70) bearing through a sliding bearing (81), and the column frame (20) is fixedly connected to the hinge seat (82); One end of the sliding bearing (81) is limited by the shoulder of the hinge shaft (70), and the other end is limited by the retaining ring (83); The hinge shaft (70) is provided with a second stud at its head end. The second stud passes through the retaining ring (83) and the second anti-loosening washer (84) in sequence and is then threadedly connected to the second round nut (85).

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