Municipal public municipal pipe well construction auxiliary device

Abstract

The utility model discloses a municipal public municipal tube well construction auxiliary device in the technical field of municipal construction equipment, which comprises an operation plate, moving mechanisms are mounted on the lower surface of the operation plate, a controller is mounted on the upper surface of the operation plate, a lifting mechanism and a clamping mechanism are mounted between the moving mechanisms, the clamping mechanism is mounted on the lifting mechanism, and the device further comprises a mounting frame. A mounting block is mounted below the mounting frame, a cylinder is mounted on the upper surface of the mounting frame, a lifting rod is mounted at the output end of the cylinder, a lifting cavity extending in the vertical direction is formed in the side face of the mounting frame and located on the upper surface of the mounting block, the lifting rod extends into the lifting cavity, and the free end of the lifting rod is fixedly connected with a pressing plate. A telescopic guide rod is fixedly mounted on the lower surface of the top plate, a movable cavity is formed in the mounting block, the telescopic guide rod extends into the movable cavity, the free end of the telescopic guide rod is rotationally connected with a clamping jaw grabbing assembly, and a reset spring sleeves the telescopic guide rod and is located between the top plate and the mounting block.

Description

Technical Field

[0001] The utility model relates to the technical field of municipal construction equipment, in particular to a construction auxiliary device for municipal public utility manholes. Background Technique

[0002] With the development of urban infrastructure construction, the developed underground pipe networks have led to an increasing number and types of manholes set in municipal engineering, including water pipe manholes, sewage manholes, power maintenance manholes, etc. During the construction process of any kind of manhole, it is necessary to open the manhole cover for construction.

[0003] For the existing patent with the authorized announcement number of CN215101767U, this patent can make the operation of opening and closing the manhole cover more labor-saving by one person, reduce the waste of manpower, and at the same time reduce the probability of accidental injury to the staff, improving safety. However, when this construction auxiliary device for municipal manholes is actually used, due to the different diameters of different manhole covers, the distances between the two lifting holes on them are also different, and it is impossible to adjust the position of the lifting rod according to the distance between the lifting holes on the actual manhole cover, so the applicable range is small. Content of the Utility Model

[0004] The purpose of the utility model is to provide a construction auxiliary device for municipal public utility manholes to solve the above-mentioned technical problems.

[0005] To achieve the above purpose, the utility model provides the following technical solutions:

[0006] A construction auxiliary device for municipal public utility manholes includes an operation board. A moving mechanism is installed on the lower surface of the operation board, and a controller is installed on the upper surface. A lifting mechanism and a clamping mechanism are installed between the moving mechanisms. The clamping mechanism is installed on the lifting mechanism and includes an installation frame. An installation block is installed below the installation frame. A cylinder is installed on the upper surface of the installation frame. The output end of the cylinder is installed with a lifting rod. A lifting cavity extending in the vertical direction is opened on the side surface of the installation frame. The lifting cavity is located on the upper surface of the installation block. The lifting rod extends into the lifting cavity, and the free end is fixedly connected with a pressing plate. A top plate is attached below the pressing plate. A telescopic guide rod is fixedly installed on the lower surface of the top plate. An activity cavity is opened in the installation block. The telescopic guide rod extends into the activity cavity, and the free end is rotatably connected with a claw grabbing assembly. A return spring is sleeved outside the telescopic guide rod. The return spring is located between the top plate and the installation block.

[0007] As a further solution of the present utility model: The jaw grasping assembly includes two rotating rods. The two rotating rods are rotatably connected to the free end of the telescopic guide rod through a first hinge. The two rotating rods are rotatably connected to the mounting block through a second hinge. Two abutting blocks are fixedly connected to the free ends of the two rotating rods. Two clamping blocks are fixedly connected to the lower surfaces of the two abutting blocks. Support blocks are fixedly connected to the opposite side surfaces of the two clamping blocks.

[0008] As a further solution of the present utility model: Activity grooves are provided at the connection ends of the two rotating rods and the telescopic guide rod. The first hinge slides along the activity groove. A mounting cavity is provided through the side surface of the mounting block. The mounting cavity communicates with the activity cavity and corresponds to the position of the first hinge.

[0009] As a further solution of the present utility model: The two abutting blocks extend towards each other, and inclined surfaces are provided at their free ends. The pressing plate is slidably connected to the lifting cavity and lifts along the lifting cavity.

[0010] As a further solution of the present utility model: The lifting mechanism includes a servo motor fixedly installed on the upper surface of the operation board. The output end of the servo motor is fixedly connected with a screw rod. The screw rod is rotatably connected to the operation board through a bearing and extends below the operation board. A first lifting block is threadedly connected to the screw rod. The first lifting block is fixedly installed on the side surface of the mounting frame.

[0011] As a further solution of the present utility model: A second lifting block is fixedly connected to the side surface of the mounting frame away from the first lifting block. A sliding rod is slidably connected to the second lifting block. The sliding rod is vertically arranged and parallel to the screw rod. The upper end of the sliding rod is fixedly installed on the lower surface of the operation board. Limit blocks are provided at the free ends of the screw rod and the sliding rod.

[0012] As a further solution of the present utility model: Both the air cylinder and the servo motor are electrically connected to the controller.

[0013] As a further solution of the present utility model: The moving mechanism includes four support legs evenly distributed at the four corners of the lower surface of the operation board. Universal wheels are provided at the free ends of the four support legs. A push handle is provided on the upper surface of the operation board.

[0014] As a further solution of the present utility model: A limiting mechanism is provided between the two support legs. The limiting mechanism includes a connecting rod installed between the opposite side surfaces of the two support legs. An electric push rod is provided on the lower surface of the connecting rod. A limiting plate is fixedly connected to the output end of the electric push rod.

[0015] Compared with the prior art, the beneficial effects of the present utility model are:

[0016] In the present utility model, the controller can control the lifting mechanism and the clamping mechanism. The lifting mechanism is used to drive the clamping mechanism to lift, and the clamping mechanism is used to clamp the manhole cover.

[0017] In the present utility model, the pressing plate can drive the top plate to move vertically downward. The top plate drives the telescopic guide rod to move vertically downward and compresses the return spring. When the pressing plate rises, the top plate loses pressure, and the return spring drives the top plate and the telescopic guide rod to move vertically upward. The above technical solution can achieve the vertical downward or upward movement of the telescopic guide rod.

[0018] In the present utility model, when the two abutting blocks are in a horizontal state, the two clamping blocks are in a vertical state, and the two supporting blocks are in a horizontal state. When the two rotating rods rotate, the two abutting blocks drive the two clamping blocks to separate from each other until the distance is greater than the diameter of the manhole cover. When the lifting mechanism drives the installation frame to move in place, the two supporting blocks are located below the manhole cover. At this time, the two rotating rods rotate in the reverse direction, the two abutting blocks drive the two clamping blocks to approach each other. While the two clamping blocks clamp the side surface of the manhole cover, the two supporting blocks support the lower side of the manhole cover, thereby realizing the clamping and fixing of the manhole cover. Since the moving range of the two clamping blocks is very large, the present utility model can be flexibly adjusted according to the different diameters of the manhole covers to clamp manhole covers with different diameters and improve the scope of application. Description of the Drawings

[0019] Figure 1 is a three-dimensional structural schematic diagram of the present utility model;

[0020] Figure 2 is a structural schematic diagram of the lifting mechanism in the present utility model;

[0021] Figure 3 is a structural schematic diagram of the clamping mechanism in the present utility model;

[0022] Figure 4 is a partial structural schematic diagram of the clamping mechanism in the present utility model.

[0023] In the figure: 1. Operating panel; 2. Moving mechanism; 21. Support leg; 22. Universal wheel; 3. Limiting mechanism; 31. Connecting rod; 32. Electric push rod; 33. Limiting plate; 4. Push handle; 5. Lifting mechanism; 51. Servo motor; 52. Screw rod; 53. First lifting block; 54. Second lifting block; 55. Slide bar; 56. Limiting block; 6. Clamping mechanism; 61. Installation frame; 611. Lifting cavity; 62. Installation block; 621. Movable cavity; 622. Installation cavity; 63. Cylinder; 64. Lifting rod; 65. Pressure plate; 66. Top plate; 67. Telescopic guide rod; 68. Return spring; 69. Claw grasping assembly; 691. Rotating rod; 692. First hinge; 693. Movable groove; 694. Second hinge; 695. Abutting block; 696. Clamping block; 697. Support block; 698. Inclined surface; 7. Controller. Detailed implementation mode

[0024] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0025] Embodiment

[0026] A construction auxiliary device for municipal public utility manholes, refer to Figures 1 - 4 , including an operating panel 1. A moving mechanism 2 is installed on the lower surface of the operating panel 1. The moving mechanism 2 includes four support legs 21 evenly distributed at the four corners of the lower surface of the operating panel 1. Universal wheels 22 are provided at the free ends of the four support legs 21. A push handle 4 and a controller 7 are provided on the upper surface of the operating panel 1; the effects achieved by the above components are: the operating panel 1 can move on the road surface through the support legs 21 and the universal wheels 22 until it moves above the manhole cover; the operating panel 1 can be pushed through the push handle 4.

[0027] As Figures 1 - 4 shown, in this implementation plan: A limiting mechanism 3 is provided between two support legs 21. The limiting mechanism 3 includes a connecting rod 31 installed between the opposite side surfaces of the two support legs 21. An electric push rod 32 is provided on the lower surface of the connecting rod 31. The electric push rod 32 is electrically connected to the controller 7. The output end of the electric push rod 32 is fixedly connected to a limiting plate 33; the effects achieved by the above components are: when the operating panel 1 moves in place, the electric push rod 32 is started through the controller 7. The electric push rod 32 drives the limiting plate 33 to move downward until it contacts the road surface. Due to the friction between the limiting plate 33 and the road surface, the operating panel 1 can be fixed to the ground.

[0028] As Figures 1 - 4As shown in the figure, in this implementation: a lifting mechanism 5 and a clamping mechanism 6 are installed between the moving mechanisms 2. The lifting mechanism 5 is installed on the operation board 1, and the clamping mechanism 6 is installed on the lifting mechanism 5. The controller 7 can control the lifting mechanism 5 and the clamping mechanism 6. The lifting mechanism 5 is used to drive the clamping mechanism 6 to lift, and the clamping mechanism 6 is used to pick up the manhole cover.

[0029] As Figures 1 - 4 shown in the figure, in this implementation: the lifting mechanism 5 includes a servo motor 51 fixedly installed on the upper surface of the operation board 1. The servo motor 51 is electrically connected to the controller 7. The output end of the servo motor 51 is fixedly connected to a screw rod 52. The extending direction of the screw rod 52 is perpendicular to the lower surface of the operation board 1. The screw rod 52 is rotatably connected to the operation board 1 through a bearing and extends below the operation board 1. A first lifting block 53 is threadedly connected to the screw rod 52. The effects achieved by the above components are: the controller 7 controls the start and stop of the servo motor 51. After the operation board 1 moves above the manhole cover and is fixed in position by the limiting mechanism 3, the servo motor 51 can drive the first lifting block 53 to lift along the length direction of the screw rod 52 through the screw rod 52. The extending direction of the screw rod 52 is perpendicular to the lower surface of the operation board 1, which can ensure that the first lifting block 53 lifts along the vertical direction. The screw rod 52 is rotatably connected to the operation board 1 through a bearing, which can ensure that during the rotation of the screw rod 52, it will not lift spirally along the operation board 1 but will rotate along the operation board 1.

[0030] As Figures 1 - 4 shown in the figure, in this implementation: the clamping mechanism 6 includes a mounting frame 61. The first lifting block 53 is fixedly installed on the side surface of the mounting frame 61. A second lifting block 54 is fixedly connected to the side surface of the mounting frame 61 away from the first lifting block 53. A sliding rod 55 is slidably connected to the second lifting block 54. The sliding rod 55 is vertically arranged and parallel to the screw rod 52. The upper end of the sliding rod 55 is fixedly installed on the lower surface of the operation board 1. Limiting blocks 56 are provided at the free ends of the screw rod 52 and the sliding rod 55. The effects achieved by the above components are: during the vertical lifting process of the first lifting block 53, it can drive the mounting frame 61 to lift along the vertical direction. The second lifting block 54 lifts along the sliding rod 55 and is fixedly connected to the mounting frame 61, so it can ensure that the mounting frame 61 stably lifts along the vertical direction. The sliding rod 55 is vertically arranged and parallel to the screw rod 52, which can ensure that the moving direction of the second lifting block 54 is parallel to that of the first lifting block 53 and ensure that the mounting frame 61 stably lifts along the vertical direction.

[0031] As Figures 1 - 4As shown in the figure, in this embodiment: an installation block 62 is installed below the installation frame 61, a cylinder 63 is installed on the upper surface of the installation frame 61, the cylinder 63 is electrically connected to the controller 7, a lifting rod 64 is installed at the output end of the cylinder 63, a lifting cavity 611 extending in the vertical direction is formed on the side surface of the installation frame 61, the lifting cavity 611 is located on the upper surface of the installation block 62, the lifting rod 64 extends into the lifting cavity 611, and the free end is fixedly connected with a pressing plate 65. The pressing plate 65 is slidably connected to the lifting cavity 611 and moves up and down along the lifting cavity 611. The effects achieved by the above components are: the controller 7 can control the start and stop of the cylinder 63; the cylinder 63 can drive the lifting rod 64 to move vertically up and down, and the lifting rod 64 drives the pressing plate 65 to move up and down along the lifting cavity 611; the lifting cavity 611 has the same extending direction as the lifting rod 64, so that the lifting rod 64 can stably drive the pressing plate 65 to move up and down along the lifting cavity 611.

[0032] As Figures 1 - 4 shown, in this embodiment: a top plate 66 is attached to the lower side of the pressing plate 65, a telescopic guide rod 67 is fixedly installed on the lower surface of the top plate 66, a movable cavity 621 is formed in the installation block 62, the telescopic guide rod 67 extends into the movable cavity 621, and the free end is rotatably connected with a jaw grasping assembly 69. A return spring 68 is sleeved outside the telescopic guide rod 67, and the return spring 68 is located between the top plate 66 and the installation block 62. The effects achieved by the above components are: the pressing plate 65 can drive the top plate 66 to move vertically downward, the top plate 66 drives the telescopic guide rod 67 to move vertically downward, and compresses the return spring 68; when the pressing plate 65 rises, the top plate 66 loses pressure, and the return spring 68 drives the top plate 66 and the telescopic guide rod 67 to move vertically upward; the above technical solution can realize the vertical downward or upward movement of the telescopic guide rod 67.

[0033] As Figures 1 - 4As shown, in this embodiment: The jaw grasping assembly 69 includes two rotating rods 691. The two rotating rods 691 are rotatably connected to the free end of the telescopic guide rod 67 through a first hinge 692. An activity groove 693 is provided at the connection end of the two rotating rods 691 and the telescopic guide rod 67. The first hinge 692 slides along the activity groove 693. A mounting cavity 622 is provided through the side of the mounting block 62. The mounting cavity 622 communicates with the activity cavity 621 and corresponds to the position of the first hinge 692. The two rotating rods 691 are rotatably connected to the mounting block 62 through a second hinge 694. The effects achieved by the above components are as follows: The first hinge 692 can rotatably connect the two rotating rods 691 and the free end of the telescopic guide rod 67. During the vertical downward or downward movement of the telescopic guide rod 67, the two rotating rods 691 will rotate along the second hinge 694. At this time, if the relative positions of the first hinge 692 and the two rotating rods 691 do not change, the two rotating rods 691 cannot rotate. Therefore, the activity groove 693 provides conditions for the relative positions of the first hinge 692 and the two rotating rods 691 to change. The first hinge 692 slides along the activity groove 693, so that during the vertical downward or downward movement of the telescopic guide rod 67, the two rotating rods 691 will rotate along the second hinge 694. The setting of the mounting cavity 622 creates conditions for mounting the first hinge 692.

[0034] As Figures 1 - 4 shown, in this embodiment: Two abutting blocks 695 are fixedly connected to the free ends of the two rotating rods 691. The two abutting blocks 695 extend in the direction of approaching each other, and the free ends are provided with inclined surfaces 698. The effects achieved by the above components are as follows: In the initial state, when the telescopic guide rod 67 does not move downward, the two abutting blocks 695 are in a horizontal state. At this time, the two abutting blocks 695 are in a state of almost touching. The two abutting blocks 695 can prevent the two rotating rods 691 from rotating excessively and limit the rotation range of the two rotating rods 691. When the telescopic guide rod 67 moves downward and the two rotating rods 691 rotate, the setting of the inclined surface 698 can enable the two abutting blocks 695 to rotate normally without being squeezed against each other and causing inability to rotate.

[0035] As Figures 1 - 4As shown in the figure, in this embodiment: clamping blocks 696 are fixedly connected to the lower surfaces of two abutting blocks 695, and support blocks 697 are fixedly connected to the opposite sides of the two clamping blocks 696; the effects achieved by the above components are as follows: when the two abutting blocks 695 are in a horizontal state, the two clamping blocks 696 are in a vertical state, and the two support blocks 697 are in a horizontal state. When the two rotating rods 691 rotate, the two abutting blocks 695 drive the two clamping blocks 696 to separate from each other until the distance therebetween is greater than the diameter of the manhole cover. When the lifting mechanism 5 drives the mounting frame 61 to move into place, the two support blocks 697 are located below the manhole cover. At this time, the two rotating rods 691 rotate in the opposite direction, the two abutting blocks 695 drive the two clamping blocks 696 to approach each other. While the two clamping blocks 696 clamp the side surface of the manhole cover, the two support blocks 697 support the lower side of the manhole cover, thereby realizing the clamping and fixing of the manhole cover; since the moving range of the two clamping blocks 696 is very large, the present utility model can be flexibly adjusted according to the different diameters of the manhole covers to clamp manhole covers with different diameters, improving the scope of application.

[0036] The working principle of the present utility model is as follows: First, the operating board 1 is pushed by the push handle 4, and the operating board 1 moves on the ground through the support legs 21 and the universal wheels 22. When the operating board 1 moves above the manhole cover, the electric push rod 32 is started through the controller 7, and the electric push rod 32 drives the limiting plate 33 to move downward until it contacts the road surface. At this time, the operating board 1 is fixed to the ground. Then, the cylinder 63 is started through the controller 7, and the cylinder 63 drives the lifting rod 64 to descend vertically. The lifting rod 64 drives the pressing plate 65 to descend along the lifting cavity 611. The pressing plate 65 drives the top plate 66 to move vertically downward. The top plate 66 drives the telescopic guide rod 67 to move vertically downward and compresses the return spring 68. When the telescopic guide rod 67 moves vertically downward, it drives the two rotating rods 691 to rotate along the second hinge 694 through the first hinge 692. The two rotating rods 691 drive the two clamping blocks 696 to separate from each other through the abutting blocks 695 until the distance is greater than the diameter of the manhole cover. Then, the servo motor 51 is started through the controller 7, and the servo motor 51 drives the screw rod 52 to rotate along the operating board 1. During the rotation of the screw rod 52, it drives the first lifting block 53 to descend along the length direction of the screw rod 52. The first lifting block 53 drives the installation frame 61 to descend until the two support blocks 697 are located below the manhole cover. Then, the controller 7 controls the cylinder 63 to contract. The cylinder 63 drives the pressing plate 65 to move vertically upward through the lifting rod 64. At this time, the top plate 66 loses pressure, and the return spring 68 drives the top plate 66 and the telescopic guide rod 67 to move vertically upward. The telescopic guide rod 67 drives the two rotating rods 691 to rotate reversely along the second hinge 694 through the first hinge 692. The two rotating rods 691 drive the two clamping blocks 696 to approach each other through the abutting blocks 695. While the two clamping blocks 696 clamp the side of the manhole cover, the two support blocks 697 support the lower side of the manhole cover, thus realizing the clamping and fixing of the manhole cover. Then, the controller 7 controls the servo motor 51 to lift the clamping mechanism 6 and the manhole cover in place. Then, the controller 7 controls the electric push rod 32 to separate the limiting plate 33 from the road surface. Finally, the manhole cover can be moved by pushing the operating board 1 with the push handle 4.

[0037] The above is only the preferred specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model, according to the technical solution and the inventive concept of the present utility model, makes equivalent substitutions or changes, and should be covered within the protection scope of the present utility model.

Claims

1. A municipal public municipal pipe well construction auxiliary device, comprising an operating panel (1), characterized in that: The operating panel (1) is provided with a moving mechanism (2) on its lower surface and a controller (7) on its upper surface; a lifting mechanism (5) and a clamping mechanism (6) are provided between the moving mechanism (2); the clamping mechanism (6) is provided on the lifting mechanism (5) and comprises a mounting frame (61); a mounting block (62) is provided below the mounting frame (61); a cylinder (63) is provided on the upper surface of the mounting frame (61); a lifting rod (64) is provided at the output end of the cylinder (63); a lifting chamber (611) extending in a vertical direction is provided on the side of the mounting frame (61); the lifting chamber (611) is located at the mounting block On the upper surface of (62), the lifting rod (64) extends into the lifting cavity (611), and the free end is fixedly connected to a pressure plate (65), a top plate (66) is attached below the pressure plate (65), a telescopic guide rod (67) is fixedly installed on the lower surface of the top plate (66), an active cavity (621) is opened in the mounting block (62), the telescopic guide rod (67) extends into the active cavity (621), and the free end is rotatably connected to a clamping claw grasping assembly (69), a reset spring (68) is provided on the outer sleeve of the telescopic guide rod (67), and the reset spring (68) is located between the top plate (66) and the mounting block (62).

2. A municipal public pipe well construction auxiliary device according to claim 1, characterized in that: The clamping claw grasping assembly (69) includes two rotating rods (691), the two rotating rods (691) are rotatably connected to the free end of the telescopic guide rod (67) through a first hinge (692), the two rotating rods (691) are rotatably connected to the mounting block (62) through a second hinge (694), the free ends of the two rotating rods (691) are fixedly connected to two abutting blocks (695), the lower surfaces of the two abutting blocks (695) are fixedly connected to clamping blocks (696), and the opposite sides of the two clamping blocks (696) are fixedly connected to supporting blocks (697).

3. A municipal public pipe well construction auxiliary device according to claim 2, characterized in that: A movable groove (693) is provided at the connecting end of the two rotating rods (691) and the telescopic guide rod (67), and the first hinge (692) slides along the movable groove (693). A mounting cavity (622) is provided through the side of the mounting block (62), and the mounting cavity (622) is connected with the movable cavity (621) and corresponds to the position of the first hinge (692).

4. A municipal public pipe well construction auxiliary device according to claim 3, characterized in that: The two abutting blocks (695) extend in a direction approaching each other, and a slope (698) is provided at a free end. The pressing plate (65) is slidably connected to the lifting chamber (611) and is lifted and lowered along the lifting chamber (611).

5. A municipal public pipe well construction auxiliary device according to claim 4, characterized in that: The lifting mechanism (5) comprises a servo motor (51) fixedly mounted on the upper surface of the operating panel (1); a screw rod (52) is fixedly connected to the output end of the servo motor (51); the screw rod (52) is rotatably connected to the operating panel (1) via a bearing and extends below the operating panel (1); a first lifting block (53) is threadedly connected to the screw rod (52); and the first lifting block (53) is fixedly mounted on the side of the mounting frame (61).

6. A municipal public pipe well construction auxiliary device according to claim 5, characterized in that: A second lifting block (54) is fixedly connected to the side of the mounting frame (61) away from the first lifting block (53); a sliding rod (55) is slidably connected to the second lifting block (54); the sliding rod (55) is vertically arranged and parallel to the screw rod (52); the upper end of the sliding rod (55) is fixedly mounted on the lower surface of the operating panel (1); and free ends of the screw rod (52) and the sliding rod (55) are provided with limit blocks (56).

7. A municipal public pipe well construction auxiliary device according to claim 6, characterized in that: The cylinder (63) and the servo motor (51) are both electrically connected to the controller (7).

8. A municipal public pipe well construction auxiliary device according to claim 7, characterized in that: The moving mechanism (2) comprises four supporting legs (21) evenly distributed at the four corners of the lower surface of the operating panel (1), the free ends of the four supporting legs (21) are provided with universal wheels (22), and the upper surface of the operating panel (1) is provided with a push handle (4).

9. A municipal public pipe well construction auxiliary device according to claim 8, characterized in that: A limiting mechanism (3) is provided between the two supporting legs (21), and the limiting mechanism (3) comprises a connecting rod (31) installed between opposite sides of the two supporting legs (21), an electric push rod (32) is provided on the lower surface of the connecting rod (31), and an output end of the electric push rod (32) is fixedly connected to a limiting plate (33).

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