Greenhouse gas emission flux collector

Abstract

The invention is suitable for the technical field of greenhouse gas detection, and provides a greenhouse gas emission flux collector, which comprises a rack, and the rack comprises a top plate and a bottom plate; the device further comprises a first adjusting assembly, the first adjusting assembly comprises supporting rods, and each supporting rod is rotationally provided with a first adjusting connecting rod; the detection mechanism is mounted at the bottom of the driving mechanism; the positioning mechanism comprises a positioning seat, a fixed top block is installed in the middle of the positioning seat, movable plates are symmetrically installed on the two sides of the positioning seat, pin rollers are installed on the movable plates, stud gears are rotatably installed between the fixed top block and the movable plates, and a connecting rod is arranged on the side, close to the supporting rod, of the driving mechanism; a second adjusting assembly connected with the connecting rod is arranged in the supporting rod. The device can be suitable for inspection wells with various calibers and depths, can automatically detect and collect greenhouse gases at different depths in the inspection wells, and is high in working efficiency and good in using effect.

Description

Technical Field

[0001] This invention belongs to the field of greenhouse gas detection technology, and in particular relates to a greenhouse gas emission flux collector. Background Technology

[0002] Greenhouse gases are gases in the atmosphere that absorb long-wave radiation reflected from the Earth's surface and then re-emit it, such as water vapor, carbon dioxide, and most refrigerants. Water vapor (H₂O), carbon dioxide (CO₂), nitrous oxide (N₂O), Freon, and methane (CH₄) are the main greenhouse gases in the Earth's atmosphere. Their effect is to warm the Earth's surface, similar to how a greenhouse traps solar radiation and heats the air inside. This warming effect of greenhouse gases is called the "greenhouse effect."

[0003] Wastewater production is enormous, with total COD and ammonia nitrogen reaching 19.88 million tons and 4.25 million tons, respectively. The wastewater collection process results in the storage of large quantities of wastewater in pipelines, which contains abundant organic substrates. Microorganisms in the pipeline sediments, biofilms, and wastewater anaerobicly degrade these organic substrates, producing large amounts of methane and carbon dioxide. Wastewater collection has become a significant source of greenhouse gases in the atmosphere. Gas flux refers to the change in the amount of gas emitted per unit time and per unit area; a positive value indicates the emission of gas from soil or water into the atmosphere, while a negative value indicates the absorption of the corresponding gas from the atmosphere by soil or water.

[0004] Currently, for calculating greenhouse gas emission fluxes from urban sewage pipe networks, existing sampling devices are simple in structure and cannot be effectively applied to manholes of different diameters and depths. This results in the inability of these devices to effectively monitor greenhouse gas emission fluxes from various manholes. Using different sampling devices for different manhole diameters would increase monitoring costs and lead to resource waste. Summary of the Invention

[0005] The purpose of this invention is to provide a greenhouse gas emission flux collector, which aims to solve the problems mentioned in the background art.

[0006] This invention is implemented as follows: a greenhouse gas emission flux collector includes a frame, a top plate, and a bottom plate below the top plate, the bottom plate being connected to the top plate via several connecting frames; it also includes: The first adjustment assembly includes several support rods arranged in a ring on the base plate, and the support rods are slidably mounted on the base plate radially. Each support rod is rotatably mounted with a first adjustment link. The end of the first adjustment link away from the support rod is connected to a drive mechanism installed at the bottom of the top plate. The drive mechanism is used to perform linear movement in the vertical direction. The first adjustment link is used to convert the linear movement of the drive mechanism in the vertical direction into the radial sliding of the support rod along the base plate. The detection mechanism is installed at the bottom of the drive mechanism and is used to monitor the greenhouse gas emission flux in the manhole; A positioning mechanism is installed at the end of a support rod away from the base plate. The positioning mechanism includes a positioning seat, a fixed top block installed in the middle of the positioning seat, movable plates symmetrically installed on both sides of the positioning seat, and a roller rotatably installed on the side of the movable plate away from the support rod. Teeth are provided on both the upper and lower sides of the fixed top block, and teeth are provided on the side of the movable plate near the fixed top block. A spur gear is rotatably installed between the fixed top block and the movable plate, and the spur gear meshes with the teeth on both the fixed top block and the movable plate. A connecting rod is provided on the side of the driving mechanism near the support rod, and a second adjusting component is provided at the end of the support rod near the positioning seat. The connecting rod passes through the side wall of the positioning seat and is connected to the second adjusting component. The second adjusting component switches the state in which the fixed top block and the roller are in contact with the manhole side wall by driving the connecting rod to move horizontally.

[0007] In a further technical solution, the driving mechanism includes a drive motor installed at the bottom of the top plate and a lifting sleeve slidably installed on the base plate in a vertical direction. The output end of the drive motor is connected to a vertically arranged lead screw, and the lifting sleeve is sleeved on the lead screw and connected to the lead screw by a thread. The ends of each of the first adjusting rods away from the support rod are rotatably installed on the side wall of the lifting sleeve.

[0008] A further technical solution is provided, wherein the detection mechanism includes a mounting base installed at the bottom of the lifting sleeve, and a pressure sensor and a flow sensor are provided at the bottom of the mounting base. The pressure sensor is used to detect the gas pressure at different depths inside the manhole, and the flow sensor is used to detect the gas flow rate at different depths inside the manhole.

[0009] In a further technical solution, each of the support rods is provided with three sets of positioning mechanisms at its end. The positioning seat in one set of the positioning mechanisms is directly connected to the end of the support rod. The other two sets of positioning mechanisms are symmetrically distributed on the upper and lower sides of the positioning mechanism connected to the support rod. The connecting rods in the three sets of positioning mechanisms are simultaneously connected to a second adjustment component.

[0010] In a further technical solution, the second adjustment component includes an electric telescopic rod installed in the support rod, the movable end of the electric telescopic rod is connected to an adjustment rod, the adjustment rod is slidably installed in the support rod, and the connecting rods in each group of positioning mechanisms are all connected to the adjustment rod.

[0011] In a further technical solution, the support rod is also provided with a third adjustment component for adjusting the distance between the positioning mechanisms located on both sides and the positioning mechanism located in the middle.

[0012] In a further technical solution, the third adjustment component includes two sliding seats symmetrically installed on the upper and lower sides of the support rod, and the interior of the sliding seats is connected to the interior of the support rod through a return spring. A second adjustment link is rotatably installed on the sliding seat, and the ends of the two second adjustment links away from the sliding seat are respectively rotatably connected to the positioning seats in a set of positioning mechanisms. Trapezoidal blocks are symmetrically arranged on both sides of the sliding seat, and a limiting platform matching the trapezoidal blocks is provided on the base plate.

[0013] This invention provides a greenhouse gas emission flux collector. In use, simply open the manhole cover, place the entire device inside the manhole, and activate the drive mechanism. The drive mechanism, via a first adjusting linkage, moves the support rods away from the base plate. The support rods then push the positioning seat towards the manhole sidewall, ultimately bringing the fixed top block in the positioning seat into contact with the manhole sidewall. Through the coordinated operation of the positioning mechanisms on each support rod, the device is secured in the manhole. Simultaneously, the drive mechanism also moves the detection mechanism downwards, positioning it at a lower level for monitoring and collecting greenhouse gases from the manhole. Furthermore, the device's position can be adjusted to monitor different heights within the manhole. Specifically, the second adjusting component in the two opposing support rods is activated. This component moves the connecting rod closer to the support rod, causing the fixed top block to retract into the positioning seat. During this process, the teeth on the fixed top block drive the spur gear to rotate. The spur gear, through the teeth on the movable plate, drives the movable plate to move horizontally in the opposite direction to the fixed top block, causing the roller at the end of the movable plate to abut against the side wall of the manhole. At this point, the device remains stable due to the limiting devices of the positioning mechanisms on the other two support rods. Then, the positioning mechanisms on the other two support rods are adjusted so that the rollers in the corresponding positioning mechanisms also contact the side wall of the manhole. At this point, all positioning mechanisms are in sliding contact with the side wall of the manhole. Under gravity, the device slides downwards stably. When it reaches the designated position, the second adjusting component simply reverses its operation, causing the fixed top block in the positioning mechanism to abut against the inner wall of the manhole again, thus fixing the device in that position. This allows for gas detection and collection at different heights within the manhole. This device is applicable to manholes of various diameters and depths, has a wide range of applications, and can automatically detect and collect greenhouse gases at different depths in manholes. It is highly efficient and effective. Attached Figure Description

[0014] Figure 1 A schematic diagram of a greenhouse gas emission flux collector provided in an embodiment of the present invention; Figure 2 A greenhouse gas emission flux collector provided in an embodiment of the present invention Figure 1 Enlarged view of point B; Figure 3 A bottom view of a greenhouse gas emission flux collector provided in an embodiment of the present invention; Figure 4 A greenhouse gas emission flux collector provided in an embodiment of the present invention Figure 3 Sectional view along direction A; Figure 5This is a schematic diagram of the positioning mechanism in a greenhouse gas emission flux collector provided in an embodiment of the present invention; Figure 6 A greenhouse gas emission flux collector provided in an embodiment of the present invention Figure 2 Enlarged view of point C.

[0015] In the attached diagram: Frame 1; Top plate 11; Connecting frame 12; Base plate 13; Drive mechanism 2; Drive motor 21; Lead screw 22; Lifting sleeve 23; Detection mechanism 3; Mounting base 31; Pressure sensor 32; Flow sensor 33; First adjustment assembly 4; Support rod 41; First adjustment connecting rod 42; Positioning mechanism 5; Positioning seat 51; Fixed top block 52; Spur gear 53; Connecting rod 54; Movable plate 55; Roller 56; Second adjustment assembly 6; Adjusting rod 61; Electric telescopic rod 62; Third adjustment assembly 7; Sliding seat 71; Second adjustment connecting rod 72; Trapezoidal block 73; Limiting platform 74. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0017] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0018] like Figure 1-5 As shown, a greenhouse gas emission flux collector according to an embodiment of the present invention includes a frame 1, the frame 1 including a top plate 11, a bottom plate 13 disposed below the top plate 11, and the bottom plate 13 being connected to the top plate 11 via a plurality of connecting frames 12; it also includes: The first adjustment component 4 includes a plurality of support rods 41 arranged in a ring on the base plate 13, and the support rods 41 are slidably mounted on the base plate 13 along the radial direction. Each support rod 41 is rotatably mounted with a first adjustment link 42. The end of the first adjustment link 42 away from the support rod 41 is connected to the drive mechanism 2 installed at the bottom of the top plate 11. The drive mechanism 2 is used to perform linear movement in the vertical direction. The first adjustment link 42 is used to convert the linear movement of the drive mechanism 2 in the vertical direction into the support rods 41 sliding radially along the base plate 13. The detection mechanism 3 is installed at the bottom of the drive mechanism 2 and is used to monitor the greenhouse gas emission flux in the manhole; A positioning mechanism 5 is installed at the end of the support rod 41 away from the base plate 13. The positioning mechanism 5 includes a positioning seat 51, a fixed top block 52 installed in the middle of the positioning seat 51, and movable plates 55 symmetrically installed on both sides of the positioning seat 51. A roller 56 is rotatably installed on the side of the movable plate 55 away from the support rod 41. Teeth are provided on both the upper and lower sides of the fixed top block 52, and teeth are provided on the side of the movable plate 55 near the fixed top block 52. The fixed top block 52 and the movable plate 55 rotate... A spur gear 53 is mounted on the drive mechanism 2, and the spur gear 53 meshes with the teeth on the fixed top block 52 and the movable plate 55. A connecting rod 54 is provided on the side of the drive mechanism 2 near the support rod 41. A second adjustment component 6 is provided on the end of the support rod 41 near the positioning seat 51. The connecting rod 54 passes through the side wall of the positioning seat 51 and is connected to the second adjustment component 6. The second adjustment component 6 switches the state in which the fixed top block 52 and the roller 56 are in contact with the manhole side wall by driving the connecting rod 54 to move horizontally.

[0019] In this embodiment of the invention, four support rods 41 are provided. Initially, the device is in a retracted state for easy carrying and storage. In this state, one end of the fixed top block 52 is located outside the positioning seat 51, and the movable plate 55 is retracted into the positioning seat 51. In use, simply open the manhole cover, place the entire device into the manhole, and activate the drive mechanism 2. The drive mechanism 2, through the first adjusting linkage 42, drives the support rods 41 to move away from the base plate 13. The support rods 41 push the positioning seat 51 towards the manhole sidewall, ultimately bringing the fixed top block 52 in the positioning seat 51 into contact with the manhole sidewall. Through the cooperation of the positioning mechanisms 5 on each support rod 41, the device can be fixed in the manhole. Simultaneously, the drive mechanism 2 can also drive the detection mechanism 3 downwards, placing it in a lower position for monitoring and collecting greenhouse gases in the manhole. Furthermore, to monitor different height positions within the manhole, the device's position can be adjusted. Specifically, the second adjustment component 6 in the two opposing support rods 41 is activated. The second adjustment component 6 drives the connecting rod 54 to move closer to the support rod 41. The connecting rod 54 can then retract the fixed top block 52 into the positioning seat 51. During this process, the teeth on the fixed top block 52 can drive the spur gear 53 to rotate. The spur gear 53 can then drive the movable plate 55 to move horizontally via the teeth on the movable plate 55, with the direction of movement of the movable plate 55 opposite to that of the fixed top block 52. This causes the roller 56 at the end of the movable plate 55 to abut against the side wall of the manhole. At this time, the device remains stable due to the limiting devices of the positioning mechanisms 5 on the other two support rods 41. Then, the positioning mechanisms 5 on the other two support rods 41 are adjusted so that the roller 56 in the corresponding positioning mechanisms 5 also contacts the side wall of the manhole. At this time, each positioning mechanism 5 slides in contact with the side wall of the manhole. Under the action of gravity, the device will slide down stably. When it moves to the designated position, the second adjustment component 6 only needs to work in reverse to make the fixed top block 52 in the positioning mechanism 5 abut against the inner wall of the manhole again, thereby fixing the device at that position, thus realizing gas detection and collection at different heights in the manhole.

[0020] like Figure 1 and 4 As shown, in a preferred embodiment of the present invention, the driving mechanism 2 includes a driving motor 21 installed at the bottom of the top plate 11 and a lifting sleeve 23 slidably installed on the bottom plate 13 in a vertical direction. The output end of the driving motor 21 is connected to a vertically arranged lead screw 22, and the lifting sleeve 23 is sleeved on the lead screw 22 and connected to the lead screw 22 by a thread. The end of each of the first adjusting connecting rods 42 away from the support rod 41 is rotatably installed on the side wall of the lifting sleeve 23.

[0021] In this embodiment of the invention, when in use, the drive motor 21 can drive the lead screw 22 to rotate, and the lead screw 22 can drive the lifting sleeve 23 to slide along its axial direction (i.e., vertical direction). The lifting sleeve 23 can drive each support rod 41 to slide simultaneously along the radial direction of the base plate 13 through the first adjusting connecting rod 42, thereby pushing each positioning mechanism 5 to contact the side wall of the manhole through the support rod 41.

[0022] like Figure 1 , 3 As shown in Figure 4, in a preferred embodiment of the present invention, the detection mechanism 3 includes a mounting base 31 installed at the bottom of the lifting sleeve 23. A pressure sensor 32 and a flow sensor 33 are provided at the bottom of the mounting base 31. The pressure sensor 32 is used to detect the gas pressure at different depths inside the manhole, and the flow sensor 33 is used to detect the gas flow rate at different depths inside the manhole.

[0023] In this embodiment of the invention, a conventional gas collection device may also be installed on the mounting base 31 to collect gas from different locations inside the manhole, facilitating subsequent laboratory analysis.

[0024] like Figure 1 , 2 As shown in Figures 4 and 5, in a preferred embodiment of the present invention, each of the support rods 41 is provided with three sets of positioning mechanisms 5 at its end. The positioning seat 51 in one set of positioning mechanisms 5 is directly connected to the end of the support rod 41. The other two sets of positioning mechanisms 5 are symmetrically distributed on the upper and lower sides of the positioning mechanism 5 connected to the support rod 41. The connecting rod 54 in the three sets of positioning mechanisms 5 is simultaneously connected to a set of second adjustment components 6.

[0025] In this embodiment of the invention, by providing multiple sets of positioning mechanisms 5 at the end of a support rod 41, the fixing effect of the device and the stability during the movement process are improved.

[0026] like Figure 5 As shown, in a preferred embodiment of the present invention, the second adjustment component 6 includes an electric telescopic rod 62 installed in the support rod 41. The movable end of the electric telescopic rod 62 is connected to an adjustment rod 61. The adjustment rod 61 is slidably installed in the support rod 41, and the connecting rods 54 in each group of positioning mechanisms 5 are connected to the adjustment rod 61.

[0027] In this embodiment of the invention, the adjusting rod 61 is a telescopic connecting rod. In use, the extension and retraction of the electric telescopic rod 62 can drive the adjusting rod 61 to slide in the support rod 41. The adjusting rod 61 can simultaneously drive each connecting rod 54 to move, thereby adjusting the fixed top block 52 and the roller 56 and switching their contact state with the manhole sidewall.

[0028] like Figure 1 , 2 As shown in Figures 4 and 6, in a preferred embodiment of the present invention, the support rod 41 is further provided with a third adjustment component 7 for adjusting the distance between the positioning mechanisms 5 located on both sides and the positioning mechanism 5 located in the middle.

[0029] In this embodiment of the invention, the third adjustment component 7 includes two sliding seats 71 symmetrically installed on the upper and lower sides of the support rod 41, and the interior of the sliding seats 71 is connected to the interior of the support rod 41 through a return spring. A second adjustment link 72 is rotatably installed on the sliding seat 71, and the ends of the two second adjustment links 72 away from the sliding seat 71 are respectively rotatably connected to the positioning seat 51 in a set of positioning mechanisms 5. Trapezoidal blocks 73 are symmetrically arranged on both sides of the sliding seat 71, and a limiting platform 74 matching the trapezoidal block 73 is provided on the base plate 13.

[0030] In the initial state, under the action of the return spring, the sliding seat 71 is in a retracted state, and the trapezoidal block 73 is not in contact with the limiting platform 74. At this time, the third adjusting component 7 can minimize the distance between the positioning mechanisms 5 on the upper and lower sides and the positioning mechanism 5 in the middle. As the support rod 41 extends, the size of the corresponding manhole on the surface continuously increases. In order to ensure the stability of the installation, the inclined surface of the trapezoidal block 73 will contact the limiting platform 74. Under the limiting action of the limiting platform 74, the trapezoidal block 73 will move away from the base plate 13, thereby driving the sliding seat 71 to move synchronously. The sliding seat 71 can drive the corresponding positioning seat 51 to move synchronously through the second adjusting link 72, thereby increasing the distance between the positioning seats 51 on both sides and the positioning seat 51 in the middle, which can increase the fixed area of ​​the device and thus improve the stability of the device.

[0031] Working Principle: In use, simply open the manhole cover, place the entire device inside the manhole, and activate the drive mechanism 2. The drive mechanism 2, via the first adjusting linkage 42, moves the support rod 41 away from the base plate 13. The support rod 41 then pushes the positioning seat 51 towards the manhole sidewall, ultimately bringing the fixed top block 52 in the positioning seat 51 into contact with the manhole sidewall. Through the cooperation of the positioning mechanisms 5 on each support rod 41, the device is fixed in the manhole. Simultaneously, the drive mechanism 2 also moves the detection mechanism 3 downwards, placing it at a lower position for monitoring and collecting greenhouse gas data from the manhole. Furthermore, the device's position can be adjusted to monitor different heights within the manhole. Specifically, the second adjusting component 6 in the two opposing support rods 41 is activated. The second adjusting component 6 drives the connecting rod 54 to move closer to the support rod 41. The connecting rod 54 can drive the fixed top block 52 to retract into the positioning seat 51. During this process, the teeth on the fixed top block 52 can drive the spur gear 53 to rotate. The spur gear 53 can drive the movable plate 55 to move horizontally through the teeth on the movable plate 55. The direction of movement of the movable plate 55 is opposite to that of the fixed top block 52, so that the roller 56 at the end of the movable plate 55 abuts against the side wall of the manhole. At this time, the device can still remain stable due to the limiting device of the positioning mechanism 5 on the other two support rods 41. Then, the positioning mechanism 5 on the other two support rods 41 is adjusted so that the roller 56 in the corresponding positioning mechanism 5 also contacts the side wall of the manhole. At this time, each positioning mechanism 5 slides in contact with the side wall of the manhole. Under the action of gravity, the device will slide down stably. When it moves to the designated position, the second adjustment component 6 only needs to work in reverse to make the fixed top block 52 in the positioning mechanism 5 abut against the inner wall of the manhole again, thereby fixing the device at that position, thus realizing gas detection and collection at different heights in the manhole.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A greenhouse gas emission flux collector, comprising a frame, the frame including a top plate, a bottom plate disposed below the top plate, and the bottom plate being connected to the top plate via a plurality of connecting frames, characterized in that, Also includes: The first adjustment assembly includes several support rods arranged in a ring on the base plate, and the support rods are slidably mounted on the base plate radially. Each support rod is rotatably mounted with a first adjustment link. The end of the first adjustment link away from the support rod is connected to a drive mechanism installed at the bottom of the top plate. The drive mechanism is used to perform linear movement in the vertical direction. The first adjustment link is used to convert the linear movement of the drive mechanism in the vertical direction into the radial sliding of the support rod along the base plate. The detection mechanism is installed at the bottom of the drive mechanism and is used to monitor the greenhouse gas emission flux in the manhole; A positioning mechanism is installed at the end of a support rod away from the base plate. The positioning mechanism includes a positioning seat, a fixed top block installed in the middle of the positioning seat, movable plates symmetrically installed on both sides of the positioning seat, and a roller rotatably installed on the side of the movable plate away from the support rod. Teeth are provided on both the upper and lower sides of the fixed top block, and teeth are provided on the side of the movable plate near the fixed top block. A spur gear is rotatably installed between the fixed top block and the movable plate, and the spur gear meshes with the teeth on both the fixed top block and the movable plate. A connecting rod is provided on the side of the driving mechanism near the support rod, and a second adjusting component is provided at the end of the support rod near the positioning seat. The connecting rod passes through the side wall of the positioning seat and is connected to the second adjusting component. The second adjusting component switches the state in which the fixed top block and the roller are in contact with the manhole side wall by driving the connecting rod to move horizontally.

2. The greenhouse gas emission flux collector according to claim 1, characterized in that, The driving mechanism includes a drive motor installed at the bottom of the top plate and a lifting sleeve slidably installed on the base plate in a vertical direction. The output end of the drive motor is connected to a vertically arranged lead screw, and the lifting sleeve is sleeved on the lead screw and connected to the lead screw by a thread. The end of each of the first adjusting links away from the support rod is rotatably installed on the side wall of the lifting sleeve.

3. The greenhouse gas emission flux collector according to claim 2, characterized in that, The detection mechanism includes a mounting base installed at the bottom of the lifting sleeve. A pressure sensor and a flow sensor are provided at the bottom of the mounting base. The pressure sensor is used to detect the gas pressure at different depths inside the manhole, and the flow sensor is used to detect the gas flow rate at different depths inside the manhole.

4. The greenhouse gas emission flux collector according to claim 1, characterized in that, Each of the support rods is provided with three sets of positioning mechanisms at its end. The positioning seat in one set of positioning mechanisms is directly connected to the end of the support rod. The other two sets of positioning mechanisms are symmetrically distributed on the upper and lower sides of the positioning mechanism connected to the support rod. The connecting rods in the three sets of positioning mechanisms are simultaneously connected to a set of second adjustment components.

5. The greenhouse gas emission flux collector according to claim 4, characterized in that, The second adjustment assembly includes an electric telescopic rod installed in the support rod. The movable end of the electric telescopic rod is connected to an adjustment rod, which is slidably installed in the support rod. The connecting rods in each of the positioning mechanisms are connected to the adjustment rod.

6. The greenhouse gas emission flux collector according to claim 4, characterized in that, The support rod is also provided with a third adjustment component for adjusting the distance between the positioning mechanisms located on both sides and the positioning mechanism located in the middle.

7. The greenhouse gas emission flux collector according to claim 6, characterized in that, The third adjustment component includes two sliding seats symmetrically installed on the upper and lower sides of the support rod, and the interior of the sliding seats is connected to the interior of the support rod through a return spring. A second adjustment link is rotatably installed on the sliding seat. The ends of the two second adjustment links away from the sliding seats are respectively rotatably connected to the positioning seats in a set of positioning mechanisms. Trapezoidal blocks are symmetrically arranged on both sides of the sliding seats, and a limiting platform matching the trapezoidal blocks is provided on the base plate.

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