Electronic instrument input loop overvoltage protection device

Abstract

The invention discloses an electronic instrument input loop overvoltage protection device, which relates to the technical field of electronic overvoltage protection and comprises an overvoltage protector, a rotating shaft is rotatably connected to the overvoltage protector in a penetrating manner, a disconnection protection switch is fixedly connected to the outer surface of the rotating shaft, and overvoltage line protection mechanisms are arranged at the upper end and the lower end of the overvoltage protector. In the case of troubleshooting and maintenance, as the input line is separated from the overvoltage protector, maintenance personnel do not need to worry about accidents caused by carelessness, so that the operation safety is improved, and the risk of electric shock suffered by subsequent users or the maintenance personnel when the subsequent users or the maintenance personnel are in contact with equipment or lines thereof is reduced; moreover, since the input line is still connected to the equipment, the circuit is switched on again due to misoperation sometimes, and potential safety risks are caused, the situation can be effectively avoided due to the separation design, and even if the switch is touched by mistake, the input line is separated from the overvoltage protector, and the circuit cannot be switched on again.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic overvoltage protection, in particular to an electronic instrument input circuit overvoltage protection device. Background Art

[0002] Electronic instrument input circuit overvoltage protection devices are important devices to protect electronic instruments from damage caused by excessive voltage. They are mainly used to monitor the voltage in the electronic instrument input circuit and take protective measures when the voltage exceeds the set threshold to disconnect the circuit input to prevent damage to the instrument. These devices are widely used in various electronic equipment, industrial control systems and household appliances.

[0003] During the operation of the existing overvoltage protection device, if an abnormality occurs, although the circuit input can be automatically disconnected, the input line is still connected to the overvoltage protection device. At this time, since the input line is still connected to the device, if there is a fault or residual charge inside the device, it will not only pose a potential safety threat (such as electric shock risk) to subsequent users or maintenance personnel when they contact the device or its lines, but also when performing troubleshooting and maintenance, the continuous connection of the input line will undoubtedly increase the complexity and difficulty of the work. When performing troubleshooting or daily maintenance, maintenance personnel must be more cautious in handling these still energized lines to avoid unnecessary accidents caused by negligence, which will invisibly prolong the time for troubleshooting and increase the overall maintenance cost.

[0004] Therefore, the present invention proposes an electronic instrument input circuit overvoltage protection device to solve the above problems. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the deficiencies in the prior art, the present invention provides an electronic instrument input circuit overvoltage protection device, which can effectively solve the problems in the prior art.

[0007] (II) Technical solution

[0008] To achieve the above object, the object of the present invention can be achieved by the following technical solutions:

[0009] An overvoltage protection device for an input circuit of an electronic instrument comprises an overvoltage protector, a rotating shaft passing through the overvoltage protector and rotatably connected thereto, a disconnection protection switch being fixedly connected to the outer surface of the rotating shaft, overvoltage line protection mechanisms being arranged at both upper and lower ends of the overvoltage protector, the overvoltage line protection mechanisms being used to automatically disconnect the connection between the input circuit and the overvoltage protector when an abnormality occurs in the input circuit, a line disconnection optimization mechanism being arranged between the overvoltage line protection mechanisms, the line disconnection optimization mechanism being used to slow down the disconnection speed on the way of disconnecting the input circuit and the overvoltage protector.

[0010] As a further solution of the present invention: the overvoltage line protection mechanism includes symmetrically arranged vertical rails, each of which is slidably connected to a T-shaped plate, each of which has symmetrical through grooves on its upper end, and a linkage shaft slidably connected between the through grooves on the same side.

[0011] As a further solution of the present invention: the outer surface of the linkage shaft is equidistantly fixedly connected with a limit plate, the limit plate is provided with a groove on the side away from the linkage shaft, the groove is rotatably connected with a clamping plate, and the lower end surface of the clamping plate is in contact with the inner bottom surface of the groove.

[0012] As a further solution of the present invention: vertical plates are symmetrically arranged on the outer surface of the linkage shaft, the vertical plates are fixedly connected to the overvoltage protector, limiting grooves are provided on the vertical plates, the linkage shafts are slidably connected in the limiting grooves, and the limiting grooves are composed of a combination of oblique grooves and vertical grooves.

[0013] As a further solution of the present invention: the line disconnection optimization mechanism includes symmetrically arranged cross rails, which are fixedly connected to the side walls of the overvoltage protector, and movable plates are slidably connected inside the cross rails. The movable plates are rotatably connected to two connecting plates on the side away from the cross rails, and the connecting plates are rotatably connected to the upper and lower side walls of the T-shaped plates on the side away from the movable plates.

[0014] As a further solution of the present invention: a reset spring is fixedly connected between the movable plate and the cross rail, a clamping hole is opened on the movable plate, a clamping column is clamped in the clamping hole, and the clamping column passes through the sliding connection with the cross rail.

[0015] As a further solution of the present invention: the upper ends of the clamping columns are fixedly connected with fixed plates, the lower ends of the fixed plates are provided with shifting plates, and the shifting plates are fixedly connected to the rotating shafts.

[0016] As a further solution of the present invention: the movable plate is rotatably connected to a lifting plate on one side close to the shift plate, and the lifting plate is rotatably connected to a lifting block on one end away from the movable plate. Support plates are provided on both sides of the lifting block, and the support plates are fixedly connected to the upper end surface of the cross rail. The lifting block is vertically slidably connected between the two support plates, and a counterweight block is fixedly connected to the upper end surface of the lifting block.

[0017] (III) Beneficial effects

[0018] Compared with the prior art, the present invention provides an electronic instrument input circuit overvoltage protection device, which has the following beneficial effects:

[0019] 1. The overvoltage line disconnect mechanism can simultaneously pull the input line and the overvoltage protector apart when the disconnect protection switch is closed, so that the overvoltage protector and its line are no longer energized. During troubleshooting and maintenance, since the input line has been separated from the overvoltage protector, maintenance personnel do not need to worry about accidents caused by negligence, thereby improving the safety of operation and reducing the risk of electric shock suffered by subsequent users or maintenance personnel when contacting the equipment or its lines. In addition, since the input line is still connected to the equipment, the circuit may be reconnected due to misoperation (such as accidentally touching the switch), resulting in potential safety risks. The separation design can effectively avoid this situation, because even if the switch is accidentally touched, the input line has been separated from the overvoltage protector and will not cause the circuit to be reconnected;

[0020] Among them, compared with the manual separation method of staff before detection, automatic separation of the input line and the overvoltage protector can be executed immediately when overvoltage is detected or maintenance is required, without human intervention, thereby reducing the safety risks caused by human errors or negligence. Manual separation may not be thoroughly executed due to improper operation, forgetfulness or time constraints, increasing the risk of electric shock or circuit reconnection.

[0021] 2. The grooves on the side walls of the limit plate can rotate when the clamping plate is driven down and close to the line connector, so as to avoid excessive squeezing of the line by the clamping plate. This can not only effectively prevent damage to the line connector and ensure the reliability and safety of the connection, but also the shape and size of the line connector will vary with different electrical equipment and systems. By adjusting the rotation angle of the clamping plate, the clamping plate can adapt to fit line connectors of different shapes and sizes, thereby improving the versatility and flexibility of the clamping plate.

[0022] 3. By setting up the line disconnection optimization mechanism, the speed of input line separation can be slowed down during the separation process of the input line and the overvoltage protector, which can avoid the impact and stress caused by the rapid separation of the input line, and the potential damage to the overvoltage protector and the input line interface, and reduce the friction and wear between the interface and the connector, thereby extending the service life of the overvoltage protector and the input line. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0024] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0025] Figure 2 For the present invention Figure 1 A schematic diagram of the enlarged structure of the middle A area;

[0026] Figure 3 For the present invention Figure 1 Schematic diagram of the enlarged structure of the middle B area;

[0027] Figure 4 This is a schematic diagram of the connection structure between the T-shaped plate and the linkage shaft of the present invention;

[0028] Figure 5 It is a schematic diagram of the connection structure of the limit plate and the clamping plate of the present invention;

[0029] Figure 6 This is a schematic diagram of the T-shaped plate connection structure of the present invention;

[0030] Figure 7 For the present invention Figure 6 Schematic diagram of the enlarged structure of the middle C area;

[0031] Figure 8 It is a schematic diagram of the connection structure between the cross rail and the movable plate of the present invention.

[0032] In the figure: 1. Overvoltage protector; 2. Disconnection protection switch; 3. Rotating shaft;

[0033] 401, T-shaped plate; 402, vertical rail; 403, linkage shaft; 404, limit plate; 405, clamping plate; 406, through groove; 407, vertical plate; 408, limit groove; 409, groove;

[0034] 501, cross rail; 502, moving plate; 503, connecting plate; 504, dial plate; 505, support plate; 506, return spring; 507, fixed plate; 508, lifting plate; 509, lifting block; 510, counterweight block; 511, clamping column; 512, clamping hole. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] An electronic instrument input circuit overvoltage protection device of this embodiment, such as Figure 1 - Figure 8 As shown, it includes an overvoltage protector 1, a rotating shaft 3 is rotatably connected to the overvoltage protector 1, a disconnection protection switch 2 is fixedly connected to the outer surface of the rotating shaft 3, and overvoltage line protection mechanisms are provided at both upper and lower ends of the overvoltage protector 1. The overvoltage line protection mechanism is used to automatically disconnect the connection between the input line and the overvoltage protector 1 when an abnormality occurs in the input circuit.

[0037] In this embodiment, Figure 1 and Figure 2As shown, the overvoltage line protection mechanism includes symmetrically arranged vertical rails 402, on which T-shaped plates 401 are slidably connected, and through grooves 406 are symmetrically opened on the upper ends of the T-shaped plates 401. A linkage shaft 403 is slidably connected between the through grooves 406 on the same side. When the T-shaped plate 401 slides on the vertical rail 402, the through grooves 406 can push the linkage shaft 403 to move up and down synchronously.

[0038] In this embodiment, Figure 4 and Figure 5 As shown, the outer surface of the linkage shaft 403 is evenly and fixedly connected with the limit plate 404, and the limit plate 404 is provided with a groove 409 on the side away from the linkage shaft 403. The clamping plate 405 is rotatably connected in the groove 409, and the lower end surface of the clamping plate 405 is in contact with the inner bottom surface of the groove 409. When the limit plate 404 drives the clamping plate 405 to slide downward, after the clamping plate 405 contacts the input line, it will slide upward in the groove 409 and lightly contact the input line. Conversely, when the limit plate 404 drives the clamping plate 405 to slide in the opposite direction, the friction between the clamping plate 405 and the input line will be increased synchronously due to the influence of the groove 409, and the two sides of the input line will be clamped and fixed, driving the input line to rise synchronously.

[0039] In this embodiment, Figure 2 As shown, vertical plates 407 are symmetrically arranged on the outer surface of the linkage shaft 403, and the vertical plates 407 are fixedly connected to the overvoltage protector 1. Limiting grooves 408 are provided on the vertical plates 407, and the linkage shafts 403 are slidably connected in the limiting grooves 408. The limiting grooves 408 are composed of a combination of oblique grooves and vertical grooves.

[0040] In the prior art, although the circuit input can be automatically disconnected, the input line is still connected to the overvoltage protection device. At this time, since the input line is still connected to the device, if there is a fault or residual charge inside the device, it will not only pose a potential safety threat (such as electric shock risk) to subsequent users or maintenance personnel when they touch the device or its line, but also the continuous connection of the input line will undoubtedly increase the complexity and difficulty of the work during troubleshooting and maintenance. Maintenance personnel must be more cautious in handling these still energized lines during troubleshooting or routine maintenance to avoid unnecessary accidents caused by negligence, which invisibly prolongs the time for troubleshooting and increases the overall maintenance cost. Compared with the prior art, the input line can be disconnected automatically. When the protective switch 2 is closed, the input line and the overvoltage protector 1 are pulled apart synchronously, so that the overvoltage protector 1 and its line are no longer energized. During troubleshooting and maintenance, since the input line has been separated from the overvoltage protector 1, maintenance personnel do not need to worry about accidents caused by negligence, thereby improving the safety of operation and reducing the risk of electric shock to subsequent users or maintenance personnel when contacting the equipment or its lines. In addition, since the input line is still connected to the equipment, the circuit may be reconnected due to misoperation (such as accidentally touching the switch), resulting in potential safety risks. The separation design can effectively avoid this situation because even if the switch is accidentally touched, the input line has been separated from the overvoltage protector 1 and will not cause the circuit to be reconnected.

[0041] In other aspects, this embodiment also provides a line disconnection optimization mechanism for slowing down the disconnection speed during the process of disconnecting the input line and the overvoltage protector 1, such as Figure 1 , Figure 3 , Figure 6 - Figure 8 As shown, the line disconnection optimization mechanism includes symmetrically arranged cross rails 501, and the cross rails 501 are fixedly connected to the side walls of the overvoltage protector 1. The inside of the cross rails 501 is slidably connected with a movable plate 502. The movable plate 502 is rotatably connected to two connecting plates 503 on the side away from the cross rails 501. The connecting plates 503 are rotatably connected to the upper and lower side walls of the T-shaped plates 401 on the side away from the movable plate 502.

[0042] In this embodiment, Figure 8 As shown, a return spring 506 is fixedly connected between the movable plate 502 and the cross rail 501, and a clamping hole 512 is opened on the movable plate 502. A clamping column 511 is clamped in the clamping hole 512. The clamping column 511 passes through the sliding connection with the cross rail 501. When the clamping column 511 and the clamping hole 512 opened on the movable plate 502 are separated, the movable plate 502 can be pulled to slide automatically between the cross rails 501 through the rebound force of the return spring 506.

[0043] In this embodiment, Figure 7 and Figure 8 As shown, the upper end of the clamping column 511 is fixedly connected to a fixing plate 507, and a dial plate 504 is arranged below the fixing plate 507. The dial plate 504 is fixedly connected to the rotating shaft 3. When the rotating shaft 3 drives the dial plate 504 to rotate, the dial plate 504 will push the fixing plate 507 upward from the bottom to drive the clamping column 511 to move.

[0044] In this embodiment, Figure 7 As shown, the movable plate 502 is rotatably connected to a lifting plate 508 on one side close to the dial plate 504, and the lifting plate 508 is rotatably connected to a lifting block 509 on one end away from the movable plate 502. Support plates 505 are arranged on both sides of the lifting block 509, and the support plates 505 are fixedly connected to the upper end surface of the cross rail 501. The lifting block 509 is vertically slidably connected between the two support plates 505, and a counterweight block 510 is fixedly connected to the upper end surface of the lifting block 509. When the movable plate 502 moves horizontally through the lifting plate 508 to push the lifting block 509 to slide vertically upward between the support plates 505, the counterweight block 510 connected to the upper end of the lifting block 509 can increase the resistance to the lifting block 509 and the movable plate 502 during the movement, thereby slowing down the moving speed of the lifting block 509 and the movable plate 502.

[0045] Compared with the prior art, the speed of separation of the input line can be slowed down during the process of separating the input line and the overvoltage protector 1, thereby avoiding the impact and stress caused by rapid separation of the input line, and causing potential damage to the interface between the overvoltage protector 1 and the input line, and reducing the friction and wear between the interface and the connector, thereby extending the service life of the overvoltage protector 1 and the input line.

[0046] The working process and principle involved in the overall content of the above embodiment are as follows:

[0047] When the overvoltage protector 1 is used to monitor the input line, if the input line is abnormal, the disconnection protection switch 2 connected to the overvoltage protector 1 will rotate on the overvoltage protector 1 through the rotating shaft 3 to close the overvoltage protector 1. During the rotation of the rotating shaft 3, the dial plates 504 connected at both ends will be driven to move synchronously from bottom to top, and contact with the fixed plate 507 set above. As the dial plate 504 continues to move, an upward thrust is applied to the fixed plate 507 from below, driving the clamping column 511 to slide vertically upward on the cross rail 501 and slide out from the clamping hole 512 opened above the movable plate 502. At this time, when the clamping column 511 and the clamping hole 512 are in contact with each other, the clamping column 511 and the clamping hole 512 are in contact with each other. After the complete separation, the return spring 506 connected between the moving plate 502 and the horizontal rail 501 will contract, pulling the moving plate 502 to move horizontally inside the horizontal rail 501. Since the connecting plate 503 is rotatably connected between the moving plate 502 and the upper and lower T-shaped plates 401, during the horizontal movement of the moving plate 502, the connecting plate 503 will be driven to move from an inclined state to a vertical state. As the inclination state of the connecting plate 503 changes, the connecting plate 503 can push the T-shaped plate 401 to slide synchronously on the vertical rail 402, and push the linkage shaft 403 to slide in the limiting groove 408 opened on the vertical plate 407 through the through groove 406 symmetrically opened on the T-shaped plate 401. When the linkage shaft 403 slides from the bottom of the limiting groove 408 to the top, since the clamping plate 405 is in contact with the surface of the input circuit, and the lower end surface of the clamping plate 405 is in contact with the bottom of the groove 409 opened on the side wall of the limiting plate 404, the clamping plate 405 will be limited by the bottom of the groove 409 and cannot rotate downward on the limiting plate 404 during the process of the linkage shaft 403 rising and passing through the limiting plate 404 to drive the clamping plate 405 to move upward synchronously. Therefore, the friction between the clamping plate 405 and the input circuit will be increased, clamping the input circuit, so that during the rising process of the clamping plate 405, the input circuit can be pulled up synchronously, so that the input circuit and the overpressure protection The input line is separated from the overvoltage protector 1 (the initial state of the input line is plugged into the overvoltage protector 1). Not only does the input line have been separated from the overvoltage protector 1 during troubleshooting and maintenance, the maintenance personnel do not need to worry about accidents caused by negligence, thereby improving the safety of operation and reducing the risk of electric shock suffered by subsequent users or maintenance personnel when touching the device or its lines. In addition, since the input line is still connected to the device, sometimes the circuit is reconnected due to misoperation (such as accidentally touching the switch), resulting in potential safety risks. The separation design can effectively avoid this situation because even if the switch is accidentally touched, the input line has been separated from the overvoltage protector 1 and will not cause the circuit to be reconnected.

[0048] In the process of the movable plate 502 moving horizontally through the connecting plate 503, the T-shaped plate 401, the through groove 406, the linkage shaft 403, the limit plate 404 and the clamping plate 405 to drive the input line and the overvoltage protector 1 to separate, the movable plate 502 will synchronously drive one end of the lifting plate 508 connected to the side wall to move horizontally, so that the lifting plate 508 moves from an inclined state to a vertical state. At this time, as the state of the lifting plate 508 changes, the lifting plate 508 will push the lifting block 509 to slide vertically upward between the two supporting plates 505. Since the upper end of the lifting block 509 is connected to the counterweight block 510, during the rising process of the lifting block 509, it will be subject to the resistance generated by the counterweight block 510, slowing down the lifting block 509 during the rising process. The speed is increased, thereby reducing the sliding speed of the moving plate 502 in the cross rail 501. When the sliding speed of the moving plate 502 slows down, the speed at which the moving plate 502 drives the input line and the overvoltage protector 1 to separate is also reduced synchronously through the connecting plate 503, the T-shaped plate 401, the through groove 406, the linkage shaft 403, the limit plate 404 and the clamping plate 405. This can avoid the impact and stress caused by the rapid separation of the input line, and the potential damage to the interface of the overvoltage protector 1 and the input line. The friction and wear between the interface and the connecting parts are reduced, thereby extending the service life of the overvoltage protector 1 and the input line. Compared with the buffering of the spring, the counterweight block 510 will not be damaged, and there is no need for staff to inspect and repair it.

[0049] When the subsequent staff drives the clamping plate 405 to fit the input line, as the clamping plate 405 follows the limiting plate 404 and the linkage shaft 403, and slides vertically downward along the limiting groove 408 opened on the vertical plate 407, when the clamping plate 405 contacts the input line, since there is a gap above the groove 409 opened on the side walls of the clamping plate 405 and the limiting plate 404, the clamping plate 405 will rotate upward in the groove 409 to prevent the clamping plate 405 from excessively squeezing the line, which can not only effectively prevent it from being damaged and ensure the reliability and safety of the connection, but also the shape and size of the line connector will vary depending on different electrical equipment and systems. By adjusting the rotation angle of the clamping plate 405, the clamping plate 405 can be adapted to fit line connectors of different shapes and sizes, thereby improving the versatility and flexibility of the clamping plate 405.

[0050] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. An overvoltage protection device for an input circuit of an electronic instrument, comprising an overvoltage protector (1), a rotating shaft (3) passing through the overvoltage protector (1) and rotatably connected thereto, a disconnection protection switch (2) being fixedly connected to the outer surface of the rotating shaft (3), characterized in that: The overvoltage protector (1) is provided with an overvoltage line protection mechanism at both the upper and lower ends, and the overvoltage line protection mechanism is used to automatically disconnect the connection between the input line and the overvoltage protector (1) when an abnormality occurs in the input circuit; A line disconnection optimization mechanism is arranged between the overvoltage line protection mechanisms, and the line disconnection optimization mechanism is used to slow down the disconnection speed during the process of disconnecting the input line and the overvoltage protector (1).

2. The electronic instrument input circuit overvoltage protection device according to claim 1, characterized in that: The overvoltage line protection mechanism comprises symmetrically arranged vertical rails (402), each of the vertical rails (402) being slidably connected to a T-shaped plate (401), each of the upper ends of the T-shaped plate (401) being symmetrically provided with through grooves (406), and a linkage shaft (403) being slidably connected between the through grooves (406) on the same side.

3. The electronic instrument input circuit overvoltage protection device according to claim 2, characterized in that: The outer surface of the linkage shaft (403) is fixedly connected to a limit plate (404) at equal distances, and a groove (409) is provided on the side of the limit plate (404) away from the linkage shaft (403). A clamping plate (405) is rotatably connected in the groove (409), and the lower end surface of the clamping plate (405) is in contact with the inner bottom surface of the groove (409).

4. The electronic instrument input circuit overvoltage protection device according to claim 3, characterized in that: The outer surface of the linkage shaft (403) is symmetrically provided with vertical plates (407), the vertical plates (407) are fixedly connected to the overvoltage protector (1), the vertical plates (407) are provided with limiting grooves (408), the linkage shaft (403) is slidably connected in the limiting grooves (408), and the limiting grooves (408) are composed of a combination of an oblique groove and a vertical groove.

5. The electronic instrument input circuit overvoltage protection device according to claim 2, characterized in that: The line disconnection optimization mechanism comprises symmetrically arranged transverse rails (501), the transverse rails (501) are fixedly connected to the side walls of the overvoltage protector (1), the interior of the transverse rails (501) are slidably connected with a movable plate (502), the side of the movable plate (502) away from the transverse rails (501) is rotatably connected to two connecting plates (503), and the side of the connecting plate (503) away from the movable plate (502) is rotatably connected to the upper and lower side walls of the T-shaped plates (401).

6. The electronic instrument input circuit overvoltage protection device according to claim 5, characterized in that: A return spring (506) is fixedly connected between the movable plate (502) and the cross rail (501), a clamping hole (512) is provided on the movable plate (502), a clamping column (511) is clamped in the clamping hole (512), and the clamping column (511) penetrates and is slidably connected to the cross rail (501).

7. The electronic instrument input circuit overvoltage protection device according to claim 6, characterized in that: The upper ends of the clamping columns (511) are fixedly connected to a fixing plate (507), a shifting plate (504) is disposed below the fixing plate (507), and the shifting plates (504) are fixedly connected to the rotating shaft (3).

8. The electronic instrument input circuit overvoltage protection device according to claim 7, characterized in that: The movable plate (502) is rotatably connected to a lifting plate (508) at one end close to the shifting plate (504), and the lifting plate (508) is rotatably connected to a lifting block (509) at one end away from the movable plate (502). Support plates (505) are arranged on both sides of the lifting block (509), and the support plates (505) are fixedly connected to the upper end surface of the cross rail (501). The lifting block (509) is vertically slidably connected between the two support plates (505), and a counterweight block (510) is fixedly connected to the upper end surface of the lifting block (509).

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