Locking device for vacuum circuit breaker
By using a locking device including a permanent magnet mechanism and a locking transmission assembly in the vacuum circuit breaker, the problems of complex structure and low space utilization in the prior art are solved, and the effective locking and safety improvement of the chassis truck when closing is achieved.
Patent Information
- Application Number
- CN202420667472.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-02
- Publication Date
- 2025-03-18
- Estimated Expiration
- 2034-04-02
AI Technical Summary
The existing vacuum circuit breaker closing locking device has a complex structure and low space utilization rate, making it difficult to effectively prevent the chassis car from entering and exiting due to artificial misoperation.
The locking device including a bracket, the first rotating shaft, a permanent magnet mechanism and a locking transmission assembly is adopted. The locking transmission assembly is driven by the movable pull rod of the permanent magnet mechanism to achieve limit locking of the chassis car, ensuring that the chassis car cannot enter and exit remotely under the closed state.
It realizes effective locking of the chassis car when the vacuum circuit breaker is closed, prevents misoperation, improves safety, and has a simple structure and high space utilization rate.
Smart Images
Figure CN222637146U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of electric power equipment, in particular to a locking device for a vacuum circuit breaker. Background Art
[0002] At present, vacuum circuit breakers refer to switch devices that can close, carry and break current under normal circuit conditions and can close, carry and break current under abnormal circuit conditions within a specified time. The opening and closing actions of vacuum circuit breakers are realized through the operating mechanism, and the closing and opening operations of vacuum circuit breakers are realized through the linkage between the operating mechanism and the main shaft on the vacuum circuit breaker. With the development of high-voltage electrical appliances and high-voltage AC vacuum circuit breakers, people have higher and higher safety requirements for power distribution products, and high-voltage AC vacuum circuit breakers cannot be shaken in and out of the chassis due to human error, which may cause casualties.
[0003] In the prior art, when the vacuum circuit breaker is closed, in order to ensure the safe operation of the vacuum circuit breaker, a trolley locking assembly for locking the chassis vehicle in the closed state and a closing locking assembly for limiting the closing device from performing secondary closing need to be provided on the operating mechanism. However, the prior art is to respectively provide structures that are linked to the trolley locking assembly and the closing locking assembly on the main shaft, resulting in a complex overall structure and low space utilization. Utility Model Content
[0004] The technical problem to be solved by the utility model is to provide a locking device for a vacuum circuit breaker, which can lock the chassis vehicle while closing the circuit breaker, and has a simple structure and high space utilization. The technical solution adopted is as follows:
[0005] A locking device for a vacuum circuit breaker, characterized in that it includes a bracket, a first rotating shaft, a permanent magnetic mechanism and a locking transmission assembly, the permanent magnetic mechanism is installed on the bracket, and the permanent magnetic mechanism has a movable pull rod that can move up and down relative to the bracket; the first rotating shaft can be rotatably installed on the bracket and runs left and right; the locking transmission assembly includes a first swing arm, a pressure plate, a first locking plate, a second locking plate and a tension spring, the middle part of the first swing arm is hinged on the bracket, the front end of the first swing arm is movably connected to the lower end of the movable pull rod of the permanent magnetic mechanism, the lower end of the pressure plate is fixedly connected to the rear end of the first swing arm, the first locking plate and the second locking plate are both fixedly installed on the first rotating shaft, the first locking plate is located at the rear and lower part of the pressure plate and contacts and cooperates with the pressure plate, and the second locking plate is located below the first locking plate; the two ends of the tension spring are respectively connected to the first locking plate and the bracket.
[0006] In the vacuum circuit breaker, the movable pull rod of the permanent magnet mechanism can move up or down under the drive of the permanent magnet drive module, and the moving end of the vacuum interrupter is driven to move up or down through the insulating pull rod assembly until the moving end of the vacuum interrupter contacts its static end or the moving and static contacts are pulled apart by a certain distance (opening distance), thus completing the opening or opening action of the vacuum circuit breaker. The bottom of the vacuum circuit breaker has a frame bottom plate, and a chassis car is arranged below the frame bottom plate. The chassis car can be remotely moved in and out relative to the vacuum circuit breaker under the drive of the propulsion mechanism; the chassis car is provided with a chassis car tongue plate, and the frame bottom plate is provided with a strip guide hole for the chassis car tongue plate to pass through, and the second locking plate is located in front of the chassis car tongue plate, and the second locking plate can enter the moving path of the chassis car tongue plate or leave the moving path of the chassis car tongue plate under the drive of the first rotating shaft.
[0007] When it is necessary to control the vacuum circuit breaker to perform a closing action, the movable pull rod of the permanent magnet mechanism moves the bracket upward under the drive of the permanent magnet drive module, driving the rear end of the first swing arm to swing downward around the hinge in the middle, and then applying a downward force to the first locking plate through the pressure plate (at this time, the first rotating shaft, the first locking plate and the second locking plate have a tendency to rotate clockwise under the action of the tension spring, so that the first locking plate can always be close to the pressure plate), so that the second locking plate rotates around the second rotating shaft by a certain angle, so that the second locking plate can enter the moving path of the chassis tongue plate (at this time, the second locking plate and the chassis tongue plate are in a vertical state or a substantially vertical state), limiting the rotation of the chassis tongue plate, so that the chassis vehicle cannot be remotely moved in and out, thereby realizing the locking function of the chassis vehicle being unable to be remotely moved in and out when the vacuum circuit breaker is closed. When it is necessary to control the vacuum circuit breaker to open the gate, the movable pull rod of the permanent magnet mechanism moves downward under the drive of the permanent magnet drive module, driving the rear end of the first swing arm to swing upward around the hinge in the middle, so that the first swing arm does not press the first locking plate through the pressure plate. At this time, the first rotating shaft, the first locking plate and the second locking plate rotate clockwise under the action of the tension spring, so that the first locking plate can always be close to the pressure plate, and the second locking plate rotates to a position staggered with the chassis tongue plate, and separates from the moving path of the chassis tongue plate, which will not limit the rotation of the chassis tongue plate, so that the chassis vehicle can be remotely moved in and out.
[0008] As a specific solution of the utility model, the number of the locking transmission assembly and the number of the permanent magnetic mechanism are both set to multiple, and the multiple locking transmission assemblies are sequentially arranged along the axial direction of the first rotating shaft. The number of permanent magnetic mechanisms and locking transmission assemblies is the same and one-to-one corresponding, and the lower end of the movable pull rod of each permanent magnetic mechanism is respectively movably connected to the front end of the first swing arm of the corresponding locking transmission assembly. When any permanent magnetic mechanism of the vacuum circuit breaker is in the closed position, the chassis vehicle cannot be remotely entered or exited.
[0009] As a preferred embodiment of the utility model, the permanent magnet mechanism includes a static iron core, a permanent magnet, an inner magnetic yoke, a moving iron core, the movable pull rod, an electromagnetic coil and a closing spring, the static iron core is installed on the bracket, the permanent magnet is installed on the static iron core, the inner magnetic yoke is sleeved in the permanent magnet, the moving iron core is arranged on the lower side of the static iron core and can move up and down relative to the static iron core, and the electromagnetic coil is installed on the moving iron core; the static iron core is provided with an up-and-down guide through hole, the middle section of the movable pull rod is located in the guide through hole, the upper section of the movable pull rod is provided with a limit block, the limit block is located on the upper side of the static iron core and cooperates with the upper opening edge of the guide through hole, the moving iron core is fixedly installed on the lower section of the movable pull rod, and the lower end of the movable pull rod is movably connected to the front end of the first swing arm; the closing spring is sleeved on the outside of the movable pull rod and is located between the static iron core and the moving iron core, and the upper and lower ends of the closing spring are respectively connected to the static iron core and the moving iron core. When it is necessary to control the vacuum circuit breaker to perform a closing action, a current in a specific direction is passed through the electromagnetic coil. This current causes it to generate a magnetic field in the opposite direction to the permanent magnet at the lower part of the magnetic circuit. The magnetic field force generated by the superposition of the two magnetic fields causes the moving iron core to move upward to the target position of closing. At this time, the closing current disappears, and the permanent magnet uses the low magnetic impedance channel provided by the moving and static iron cores and the thrust of the closing spring to keep the moving iron core in a stable closed position; when it is necessary to control the vacuum circuit breaker to perform an opening action, after the permanent magnet drive module passes a current in the opposite direction through the electromagnetic coil, the current generates a magnetic field on the upper part of the moving iron core that is the same as the permanent magnet magnetic field, reducing the magnetic attraction on the moving iron core, causing it to move downward to the target position of opening. At this time, the moving iron core is kept in a stable opening position under the repulsive force of the permanent magnet and the limiting action of the limit block.
[0010] As a preferred embodiment of the utility model, the locking device for vacuum circuit breaker further includes a second rotating shaft and an indicator assembly, the second rotating shaft can be rotatably mounted on the bracket and is parallel to the first rotating shaft, and the indicator assembly is mounted on the second rotating shaft; the locking transmission assembly also includes a first connecting arm, a second connecting arm and a second swing arm, the lower end of the first connecting arm is fixedly connected to the rear end of the first swing arm, the front end of the second connecting arm is hinged to the upper end of the first connecting arm, the second swing arm is fixedly mounted on the second rotating shaft, and the first end of the second swing arm is hinged to the rear end of the second connecting arm. Specifically, the locking device for vacuum circuit breaker may also include an auxiliary switch, which is mounted on the bracket and is located on one side of the indicator assembly. When the movable pull rod of the permanent magnet mechanism moves up or down under the drive of the permanent magnet drive module, the first swing arm swings up and down around the central hinge driven by the movable pull rod of the permanent magnet mechanism, and then the second rotating shaft and the indicator assembly thereon are driven to rotate clockwise or counterclockwise through the first connecting arm, the second connecting arm and the second swing arm, and the indicator assembly is used to provide the state quantity and indication.
[0011] When the number of the permanent magnetic mechanisms is set to be multiple, the number of the signboard assemblies is generally also set to be multiple. The multiple signboard assemblies are arranged in sequence along the axial direction of the second rotating shaft, and each signboard assembly corresponds to the position of the corresponding permanent magnetic mechanism.
[0012] As a further preferred embodiment of the present invention, the middle part of the first swing arm is hinged to the bracket through a first round pin running left and right, the lower end of the pressure plate and the lower end of the first connecting arm are fixedly connected to the rear end of the first swing arm through a hexagonal pin running left and right, the front end of the second connecting arm is hinged to the upper end of the first connecting arm through a second round pin running left and right, and the front end of the second swing arm is hinged to the second end of the second connecting arm through a third round pin running left and right.
[0013] Compared with the prior art, the utility model has the following advantages:
[0014] This locking device for vacuum circuit breaker can achieve the function of limiting and locking the chassis vehicle while closing the vacuum circuit breaker through the permanent magnet mechanism, the first rotating shaft, the first swing arm, the pressure plate, the first locking plate, the second locking plate and the tension spring. It has the characteristics of preventing misoperation and high safety factor, and has a simple structure and high space utilization. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 It is a structural schematic diagram of a locking device for a vacuum circuit breaker according to a preferred embodiment of the utility model.
[0016] Figure 2 It is a schematic diagram of the connection and cooperation between the bracket, the first rotating shaft and multiple locking transmission components in the preferred embodiment of the utility model.
[0017] Figure 3 yes Figure 2 Side view of .
[0018] Figure 4 It is a structural schematic diagram of the locking transmission component, the auxiliary switch and the indicator sign component in the preferred embodiment of the utility model in the closed state.
[0019] Figure 5 It is a structural schematic diagram of the locking transmission component, the auxiliary switch and the indicator sign component in the preferred embodiment of the utility model in the open state.
[0020] Figure 6 It is a structural schematic diagram of the permanent magnet mechanism in the preferred embodiment of the utility model in the closed state.
[0021] Figure 7 It is a structural schematic diagram of the permanent magnet mechanism in the preferred embodiment of the utility model in the open state. DETAILED DESCRIPTION
[0022] like Figure 1-Figure 7 As shown, the locking device for vacuum circuit breaker includes a bracket 1, a first rotating shaft 2, a second rotating shaft 3, a permanent magnetic mechanism 4, a locking transmission assembly 5, an auxiliary switch 6 and an indicator assembly 7. The permanent magnetic mechanism 4 is installed on the bracket 1, and the permanent magnetic mechanism 4 has a movable pull rod 40 that can move up and down relative to the bracket 1; the first rotating shaft 2 and the second rotating shaft 3 can be rotatably installed on the bracket 1 and are in a left-right direction; the locking transmission assembly 5 includes a first swing arm 51, a pressure plate 52, a first locking plate 53, a second locking plate 54, a tension spring 55, a first connecting arm 56, a second connecting arm 57 and a second swing arm 58. The middle part of the first swing arm 51 is hinged on the bracket 1, and the front end of the first swing arm 51 is movably connected to the lower end of the movable pull rod 40 of the permanent magnetic mechanism 4. The pressure plate 5 2 and the lower end of the first connecting arm 56 are fixedly connected to the rear end of the first swing arm 51, the first locking plate 53 and the second locking plate 54 are both fixedly mounted on the first rotating shaft 2, the first locking plate 53 is located at the rear and lower part of the pressure plate 52 and contacts and cooperates with the pressure plate 52, and the second locking plate 54 is located below the first locking plate 53; the two ends of the tension spring 55 are respectively connected to the first locking plate 53 and the bracket 1; the front end of the second connecting arm 57 is hinged to the upper end of the first connecting arm 56, the second swing arm 58 is fixedly mounted on the second rotating shaft 3, and the first end of the second swing arm 58 is hinged to the rear end of the second connecting arm 57; the indicator assembly 7 is mounted on the second rotating shaft 3, and the auxiliary switch 6 is mounted on the bracket 1 and is located on one side of the indicator assembly 7.
[0023] In this embodiment, the permanent magnet mechanism 4 includes a movable pull rod 40, a static iron core 41, a permanent magnet 42, an inner magnetic yoke 43, a moving iron core 44, an electromagnetic coil 45 and a closing spring 46. The static iron core 41 is mounted on the bracket 1, the permanent magnet 42 is mounted on the static iron core 41, the inner magnetic yoke 43 is sleeved in the permanent magnet 42, the moving iron core 44 is arranged at the lower side of the static iron core 41 and can move up and down relative to the static iron core 41, and the electromagnetic coil 45 is mounted on the moving iron core 44; the static iron core 41 is provided with a guide through hole 45 extending up and down. 11. The middle section of the movable pull rod 40 is in the guide through hole 411. The upper section of the movable pull rod 40 is provided with a limit block 401. The limit block 401 is located on the upper side of the static iron core and cooperates with the upper opening edge of the guide through hole 411. The moving iron core 44 is fixedly installed on the lower section of the movable pull rod 40. The closing spring 46 is sleeved on the outside of the movable pull rod 40, and the upper and lower ends of the closing spring 46 are respectively connected to the static iron core 41 and the moving iron core 44; the lower end of the movable pull rod 40 is movably connected to the front end of the first swing arm 51. When it is necessary to control the vacuum circuit breaker to perform a closing action, a current in a specific direction is passed through the electromagnetic coil 45. This current causes it to generate a magnetic field in the opposite direction to the permanent magnet 42 at the lower part of the magnetic circuit. The magnetic field force generated by the superposition of the two magnetic fields causes the moving iron core 44 to move upward to the target closing position. At this time, the closing current disappears, and the permanent magnet 42 uses the low magnetic impedance channel provided by the moving and static iron cores 41 and the thrust of the closing spring 46 to keep the moving iron core 44 in a stable closed position; when it is necessary to control the vacuum circuit breaker to perform an opening action, after the permanent magnet drive module passes a current in the opposite direction through the electromagnetic coil 45, the current generates a magnetic field in the upper part of the moving iron core that is the same as the magnetic field of the permanent magnet 42, reducing the magnetic attraction on the moving iron core 44, causing it to move downward to the target opening position. At this time, the moving iron core 44 is kept in a stable opening position under the repulsive force of the permanent magnet 42 and the limiting action of the limit block 401.
[0024] In this embodiment, the middle part of the first swing arm 51 is hinged to the bracket 1 through a first round pin 511 running left and right, the lower end of the pressure plate 52 and the lower end of the first connecting arm 56 are fixedly connected to the rear end of the first swing arm 51 through a hexagonal pin 512 running left and right, the front end of the second connecting arm 57 is hinged to the upper end of the first connecting arm 56 through a second round pin 513 running left and right, and the front end of the second swing arm 58 is hinged to the second end of the second connecting arm 57 through a third round pin 514 running left and right.
[0025] In this embodiment, the number of the locking transmission assembly 5, the permanent magnet mechanism 4, and the indicator assembly 7 are all set to multiple, and the multiple locking transmission assemblies 5 are sequentially arranged along the axial direction of the first rotating shaft 2. The number of the permanent magnet mechanism 4 and the locking transmission assembly 5 is the same and one-to-one corresponding, and the lower end of the movable pull rod 40 of each permanent magnet mechanism 4 is respectively movably connected to the front end of the first swing arm 51 of the corresponding locking transmission assembly 5; multiple indicator assembly 7 are sequentially arranged along the axial direction of the second rotating shaft 3, and each indicator assembly 7 corresponds to the position of the corresponding permanent magnet mechanism 4. When any permanent magnet mechanism 4 of the vacuum circuit breaker is in the closed position, the chassis vehicle cannot be remotely entered or remotely exited.
[0026] The following is a brief description of the working principle of the locking device for vacuum circuit breaker:
[0027] In the vacuum circuit breaker, the movable rod 40 of the permanent magnet mechanism 4 can move upward or downward relative to the bracket 1 under the drive of the permanent magnet drive module 100, and drive the moving end of the vacuum interrupter to move upward or downward through the insulating rod assembly until the moving end of the vacuum interrupter contacts with its static end or the moving and static contacts are pulled apart by a distance (opening distance), thereby completing the opening or opening action of the vacuum circuit breaker. The bottom of the vacuum circuit breaker has a frame bottom plate, and a chassis car is arranged below the frame bottom plate. The chassis car can be remotely moved in and out relative to the vacuum circuit breaker under the drive of the propulsion mechanism; the chassis car tongue plate 201 is arranged on the chassis car tongue plate, and the frame bottom plate is provided with a strip guide hole for the chassis car tongue plate 201 to pass through, and the second locking plate 54 is located in front of the chassis car tongue plate 201, and the second locking plate 54 can enter the moving path of the chassis car tongue plate 201 or leave the moving path of the chassis car tongue plate 201 under the drive of the first rotating shaft 2.
[0028] When it is necessary to control the vacuum circuit breaker to close, the movable pull rod 40 of the permanent magnet mechanism 4 moves upward under the drive of the permanent magnet drive module 100, driving the rear end of the first swing arm 51 to swing downward around the first round pin 511, and then applying a downward force to the first locking plate 53 through the pressure plate 52 (at this time, the first rotating shaft 2, the first locking plate 53 and the second locking plate 54 have a tendency to rotate clockwise under the action of the tension spring 55, so that the first locking plate 53 can always be close to the pressure plate 52), so that the second locking plate 54 rotates around the second rotating shaft 3 by a certain angle, so that the second locking plate 54 can rotate to the second rotating shaft 3. 54 is able to enter the moving path of the chassis tongue plate 201 (at this time, the second locking plate 54 and the chassis tongue plate 201 are in a vertical state or a substantially vertical state), limiting the rotation of the chassis tongue plate 201, so that the chassis vehicle cannot be remotely moved in or out, thereby realizing the locking function of the chassis vehicle being unable to be remotely moved in or out when the vacuum circuit breaker is closed; at the same time, the first swing arm 51 drives the second rotating shaft 3 and the indicator sign assembly 7 thereon to rotate counterclockwise through the first connecting arm 56, the second connecting arm 57 and the second swing arm, and the auxiliary switch 6 and the indicator sign assembly 7 are used to provide the function of providing status quantity and indication.
[0029] When it is necessary to control the vacuum circuit breaker to open the gate, the movable pull rod 40 of the permanent magnet mechanism 4 moves downward under the drive of the permanent magnet drive module 100, driving the rear end of the first swing arm 51 to swing upward around the first round pin 511, so that the first swing arm 51 does not press the first locking plate 53 through the pressure plate 52. At this time, the first rotating shaft 2, the first locking plate 53 and the second locking plate 54 rotate clockwise under the action of the tension spring 55, so that the first locking plate 53 can always be close to the pressure plate 52, and the second locking plate 54 rotates to a position offset from the chassis tongue plate 201, and is separated from the moving path of the chassis tongue plate 201, which will not limit the rotation of the chassis tongue plate 201, so that the chassis vehicle can be remotely entered and exited; at the same time, the first swing arm 51 drives the second rotating shaft 3 and the indicator plate assembly 7 thereon to rotate clockwise through the first connecting arm 56, the second connecting arm 57 and the second swing arm, and the auxiliary switch 6 and the indicator plate assembly 7 are used to provide the function of providing state quantity and indication.
[0030] In addition, it should be noted that the names of the various parts of the specific embodiments described in this specification may be different, and any equivalent or simple changes made based on the structure, features and principles described in the utility model patent concept are included in the protection scope of the utility model patent. The technical personnel of the technical field to which the utility model belongs can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the utility model or exceed the scope defined by the claims, they should all fall within the protection scope of the utility model.
Claims
1. A locking device for a vacuum circuit breaker, characterized in that: It includes a bracket, a first rotating shaft, a permanent magnet mechanism and a locking transmission assembly. The permanent magnet mechanism is installed on the bracket, and the permanent magnet mechanism has a movable pull rod that can move up and down relative to the bracket; the first rotating shaft can be rotatably installed on the bracket and runs left and right; the locking transmission assembly includes a first swing arm, a pressure plate, a first locking plate, a second locking plate and a tension spring. The middle part of the first swing arm is hinged on the bracket, the front end of the first swing arm is movably connected to the lower end of the movable pull rod of the permanent magnet mechanism, the lower end of the pressure plate is fixedly connected to the rear end of the first swing arm, the first locking plate and the second locking plate are both fixedly installed on the first rotating shaft, the first locking plate is located at the rear and lower part of the pressure plate and contacts and cooperates with the pressure plate, and the second locking plate is located below the first locking plate; the two ends of the tension spring are respectively connected to the first locking plate and the bracket.
2. A locking device for a vacuum circuit breaker according to claim 1, characterized in that: The number of the locking transmission components and the permanent magnet mechanisms are both set to multiple, and the multiple locking transmission components are arranged in sequence along the axial direction of the first rotating shaft. The number of permanent magnet mechanisms and locking transmission components is the same and corresponds one to one, and the lower end of the movable pull rod of each permanent magnet mechanism is movably connected to the front end portion of the first swing arm of the corresponding locking transmission component.
3. A locking device for a vacuum circuit breaker according to claim 1, characterized in that: The permanent magnet mechanism includes a static iron core, a permanent magnet, an inner magnetic yoke, a moving iron core, the movable pull rod, an electromagnetic coil and a closing spring. The static iron core is installed on the bracket, the permanent magnet is installed on the static iron core, the inner magnetic yoke is sleeved in the permanent magnet, the moving iron core is arranged on the lower side of the static iron core and can move up and down relative to the static iron core, and the electromagnetic coil is installed on the moving iron core; the static iron core is provided with an up-and-down guide through hole, the middle section of the movable pull rod is located in the guide through hole, the upper section of the movable pull rod is provided with a limit block, the limit block is located on the upper side of the static iron core and cooperates with the upper opening edge of the guide through hole, the moving iron core is fixedly installed on the lower section of the movable pull rod, and the lower end of the movable pull rod is movably connected to the front end of the first swing arm; the closing spring is sleeved on the outside of the movable pull rod and is located between the static iron core and the moving iron core, and the upper and lower ends of the closing spring are respectively connected to the static iron core and the moving iron core.
4. A locking device for a vacuum circuit breaker according to any one of claims 1 to 3, characterized in that: The locking device for the vacuum circuit breaker also includes a second rotating shaft and an indicator sign assembly. The second rotating shaft can be rotatably mounted on the bracket and is parallel to the first rotating shaft, and the indicator sign assembly is mounted on the second rotating shaft; the locking transmission assembly also includes a first connecting arm, a second connecting arm and a second swing arm. The lower end of the first connecting arm is fixedly connected to the rear end of the first swing arm, the front end of the second connecting arm is hinged to the upper end of the first connecting arm, the second swing arm is fixedly mounted on the second rotating shaft, and the first end of the second swing arm is hinged to the rear end of the second connecting arm.
5. A locking device for a vacuum circuit breaker according to claim 4, characterized in that: The middle part of the first swing arm is hinged to the bracket through a first round pin running left and right, the lower end of the pressure plate and the lower end of the first connecting arm are fixedly connected to the rear end of the first swing arm through a hexagonal pin running left and right, the front end of the second connecting arm is hinged to the upper end of the first connecting arm through a second round pin running left and right, and the front end of the second swing arm is hinged to the second end of the second connecting arm through a third round pin running left and right.