Portable electromagnetic brake with symmetrical structure

Abstract

This utility model discloses a portable electromagnetic brake with a symmetrical structure, including a slotted disc, brake discs, and cover plates. An electromagnetic coil and a first elastic element are installed within the slotted disc. There is one slotted disc, and two brake discs and two cover plates. The two brake discs are located on opposite sides of the slotted disc, and the two cover plates are located on the outer sides of the two brake discs. A second elastic element is installed inside the brake disc or between the brake disc and the slotted disc. The second elastic element repels the first elastic element, but it also attracts the electromagnetic coil when the coil is energized. This utility model, through its symmetrical structure consisting of one slotted disc, two brake discs, and two cover plates, eliminates the need to distinguish between the front and back when installing the entire electromagnetic brake onto a robot, simplifying and improving production assembly efficiency. Furthermore, the braking force is provided by the two brake discs, resulting in a larger maximum braking torque and a wider torque adjustment range, enhancing adaptability and meeting more application needs.

Description

Technical Field

[0001] This utility model belongs to the field of electromagnetic brake production technology, specifically relating to a portable electromagnetic brake with a symmetrical structure. Background Technology

[0002] Electromagnetic brakes are widely used in various electromechanical equipment to achieve braking and de-braking functions. For example, the joint modules of humanoid robots require electromagnetic brakes. With the application of humanoid robots, issues of stability and safety have arisen. Specifically, humanoid robots need to brake smoothly in the event of sudden power loss, loss of control, or overload, ensuring the safety of surrounding personnel and property. Therefore, higher requirements are placed on the braking torque and dynamic smooth control of electromagnetic brakes in humanoid robots. Simultaneously, the multiple drive joints and sensors of humanoid robots need to be connected through internal wiring harnesses, requiring each component to have a sufficiently large hollow dimension to accommodate the wiring. Furthermore, the symmetrical structure and lightweight design requirements of humanoid robots also necessitate that components be symmetrical and weight-reduced.

[0003] A traditional electromagnetic brake mainly consists of a slotted disc (also called a stator), an armature, a brake disc (also called a friction disc), and a cover plate. The armature is located between the slotted disc and the brake disc, and the brake disc is located between the armature and the cover plate. An electromagnetic coil and a compression spring are installed inside the slotted disc, with the compression spring pressing against the armature. The slotted disc and the cover plate are connected near their edges by multiple screws passing through corresponding through holes in the armature. The brake disc is located between these screws, and a keyway is provided in the central hole wall of the brake disc for circumferential connection with the drive shaft. During operation, the electromagnetic coil is energized, generating an electromagnetic force that attracts the armature, overcoming the spring force, releasing the brake disc and allowing the drive shaft to rotate normally, thus releasing the brake. When the electromagnetic coil is de-energized, the electromagnetic force disappears, and the compression spring pushes the armature to press the brake disc against the cover plate, generating a frictional torque that quickly stops the drive shaft, achieving the braking function.

[0004] The aforementioned traditional electromagnetic brakes have the following drawbacks: 1. The armature, brake disc, and cover plate are all one unit and are located sequentially on one side of the slot, forming an asymmetrical structure. When installing the entire electromagnetic brake onto the robot, it is necessary to distinguish between the front and back sides and stack them accordingly. There is no foolproof design, which reduces production and assembly efficiency. At the same time, the braking force relies entirely on the elastic force generated by the compression spring on the same armature, and its maximum braking torque is not large enough, and the torque adjustable range is small. 2. Using the spring force to push the armature to press the brake disc has two drawbacks. First, the spring is a mechanical component with a limited lifespan. The longer it is used, the less elastic it becomes, which will reduce the braking torque and reduce the braking effect. Second, the armature component is necessary, which will increase the thickness and weight of the entire product, making it inconvenient to use and increasing production costs. 3. The electromagnetic coil and compression spring in the slot are located on the inner and outer rings of the slot, respectively. The effective contact area between the brake disc and the armature and cover plate corresponds only to the outer ring of the slot, resulting in a small friction area, which leads to low braking torque and difficulty in adjustment. 4. The friction surface between the brake disc and the cover plate is a plane perpendicular to the center line of the brake disc. If the product diameter cannot be increased while ensuring sufficient friction, the hollow diameter of the product can only be reduced, making it difficult to pass multiple wire harnesses or oil and gas pipes through the hollow part of the product, thus limiting its application. Utility Model Content

[0005] The purpose of this invention is to provide a portable electromagnetic brake with a symmetrical structure in order to solve the above-mentioned problems.

[0006] This utility model achieves the above objectives through the following technical solutions: A portable electromagnetic brake with a symmetrical structure includes a slotted disc, a brake disc, and a cover plate. The brake disc is located between the slotted disc and the cover plate. An electromagnetic coil and a first elastic element are installed inside the slotted disc. There is one slotted disc and two brake discs and two cover plates. The two brake discs are located on the outer sides of the slotted disc, and the two cover plates are located on the outer sides of the two brake discs. A second elastic element is installed inside the brake disc or between the brake disc and the slotted disc. The second elastic element has a repulsive force with the first elastic element, and the second elastic element can generate an attractive force with the electromagnetic coil when the electromagnetic coil is energized.

[0007] Specifically, depending on the actual application requirements, the first elastic element is a plurality of slotted permanent magnets evenly distributed along the circumferential direction, and the second elastic element is a plurality of brake disc permanent magnets installed in the brake disc and evenly distributed along the circumferential direction, wherein the magnetic poles of the slotted permanent magnets near the brake disc and the magnetic poles of the brake disc permanent magnets near the slots have the same polarity; or, the first elastic element is a plurality of compression springs evenly distributed along the circumferential direction, and the second elastic element is an armature installed between the brake disc and the slots.

[0008] Preferably, in order to extend the normal service life and reduce the overall thickness of the product, the first elastic element is a plurality of slotted permanent magnets evenly distributed along the circumference, and the second elastic element is a plurality of brake disc permanent magnets installed in the brake disc and evenly distributed along the circumference. The magnetic poles of the slotted permanent magnets near the corresponding brake disc and the magnetic poles of the brake disc permanent magnets near the slotted end have the same polarity.

[0009] Preferably, in order to reduce the radial width of the slotted disk and achieve a larger hollow diameter, there are multiple electromagnetic coils arranged uniformly along the circumferential direction, and the multiple electromagnetic coils and the multiple slotted disk permanent magnets are arranged along the circumferential direction of the same virtual circle.

[0010] Preferably, in order to reduce the thickness of the slotted disc while meeting functional requirements, thereby reducing the overall thickness and volume of the electromagnetic brake, and to facilitate the separate control of the braking torque of the two brake discs to achieve better torque adjustment, multiple slotted disc permanent magnets are respectively installed in multiple through holes of the slotted disc. The magnetic poles of the multiple brake disc permanent magnets in the two brake discs are of the same polarity as the corresponding magnetic poles of the slotted disc permanent magnets. Multiple recesses are provided on both sides of the slotted disc, and an electromagnetic coil is installed in each recess. An electromagnetic coil is installed between every two adjacent slotted disc permanent magnets. Multiple countersunk holes are provided on the side surface of the brake disc near the slotted disc, and a brake disc permanent magnet is installed in each countersunk hole.

[0011] Preferably, in order to further reduce the thickness of the slot, the plurality of electromagnetic coils located on the same side of the slot are arranged sequentially at intervals in the circumferential direction, and the two adjacent electromagnetic coils located on both sides of the slot are arranged in a staggered manner in the circumferential direction.

[0012] Preferably, in order to increase the friction area between the brake disc and the cover plate to achieve a larger braking torque without increasing the radial dimension, and at the same time to achieve a larger hollow diameter to meet application requirements, an annular friction pad is bonded to the side surface of the brake disc near the corresponding cover plate. The side surface of the annular friction pad near the corresponding cover plate and the side surface of the cover plate near the corresponding brake disc are inclined planes in mutual contact, and the inclined plane has an angle of 60°-85° with the center line of the brake disc.

[0013] Preferably, in order to further reduce the radial dimension occupied by the slotted disc and the brake disc to achieve a larger hollow diameter, the brake disc is provided with an L-shaped relief groove near the outer wall of the slotted disc, and the portion of the slotted disc near the inner wall is placed in the relief groove of the two brake discs.

[0014] Preferably, in order to facilitate assembly and minimize the radial space occupied and weight of the product, the edge of the slot is provided with a plurality of slot connection lugs that protrude outward in the circumferential direction and are evenly distributed along the circumferential direction, and the edge of the cover plate is provided with a plurality of cover plate connection lugs that protrude outward in the circumferential direction and are evenly distributed along the circumferential direction. A plurality of connecting screws located on both sides of the slot are respectively connected to the plurality of screw holes on the plurality of cover plate connection lugs after passing through the through holes on the plurality of cover plate connection lugs.

[0015] The beneficial effects of this utility model are as follows: This invention utilizes a symmetrical structure consisting of a slotted disc, two brake discs, and two cover plates. When installing the entire electromagnetic brake onto a robot, there is no need to distinguish between the front and back sides, making installation simple and efficient, thus improving production and assembly efficiency. Simultaneously, the braking force is provided by the two brake discs, resulting in a larger maximum braking torque and a wider torque adjustment range, enhancing adaptability and meeting more application needs. By installing permanent magnets in the slotted disc and brake discs, a permanent magnetic repulsion force is generated between them, pressing the brake discs firmly against the cover plates to achieve the braking function. The electromagnetic coil, when energized, generates a magnetic field to overcome this repulsion force, attracting the brake discs to a position with gaps between them and both the slotted disc and the cover plates, thus releasing the brakes. This eliminates the need for the compression spring and armature of traditional electromagnetic brakes. Furthermore, the permanent magnetic repulsion force does not decrease with use and can be maintained. The braking torque remains constant or changes minimally, ensuring long-term stable braking performance. Reducing the armature decreases the overall thickness and weight of the product, facilitating application and lowering production costs. By arranging multiple electromagnetic coils and multiple slotted permanent magnets along the circumference of a virtual circle directly corresponding to the brake disc, the radial dimension of the slotted disc is significantly reduced without affecting the friction area. This not only ensures sufficient braking torque and facilitates torque adjustment through the switching on / off state and current of the electromagnetic coils, but also increases the hollow diameter of the product, allowing for the passage of multiple wire harnesses or oil / gas pipes through the hollow portion, better meeting application requirements. Furthermore, by designing the friction surface between the annular friction pad and the cover plate of the brake disc as a slanted plane, the radial dimension of the brake disc is reduced while maintaining friction, increasing the hollow diameter of the product and better meeting application needs. Attached Figure Description

[0016] Figure 1 This is a top perspective view of the portable electromagnetic brake with a symmetrical structure described in this utility model; Figure 2 This is a top view of the portable electromagnetic brake with a symmetrical structure described in this utility model; Figure 3 yes Figure 2 The enlarged sectional view AA in the figure is also the main sectional view of the portable electromagnetic brake with symmetrical structure described in this utility model. Figure 4 This is a top perspective view of the slot of the portable electromagnetic brake with a symmetrical structure according to the present invention. Figure 5 This is a bottom perspective view of the slot of the portable electromagnetic brake with a symmetrical structure described in this utility model. Figure 6This is a top perspective view of the brake disc of the portable electromagnetic brake with a symmetrical structure as described in this utility model. Figure 7 This is a top view of the brake disc of the portable electromagnetic brake with a symmetrical structure described in this utility model; Figure 8 yes Figure 7 The enlarged sectional view of BB in the figure is also the main sectional view of the brake disc of the portable electromagnetic brake with symmetrical structure described in this utility model.

[0017] In the diagram, 1-connecting screw, 2-cover plate, 3-cover plate connecting lug, 4-bushing, 5-slotted plate, 6-slotted plate mounting lug, 7-slotted plate connecting lug, 8-keyway, 9-annular friction plate, 10-brake disc, 11-slotted plate permanent magnet, 12-brake disc permanent magnet, 13-electromagnetic coil, 14-leaking groove, 15-sloping plane. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings: like Figures 1-8 As shown, the portable electromagnetic brake with a symmetrical structure of this utility model includes a slotted plate 5, a brake disc 10, and a cover plate 2. The brake disc 10 is located between the slotted plate 5 and the cover plate 2. An electromagnetic coil 13 and a first elastic element (refer to the slotted plate permanent magnet 11 below) are installed in the slotted plate 5. There is one slotted plate 5, and two brake discs 10 and two cover plates 2. The two brake discs 10 are located on the outer sides of the slotted plate 5, and the two cover plates 2 are located on the outer sides of the two brake discs 10. A second elastic element (refer to the brake disc permanent magnet 12 below) is installed in the brake disc 10 or between the brake disc 10 and the slotted plate 5. The second elastic element has a repulsive force with the first elastic element, and the second elastic element can generate an attractive force with the electromagnetic coil 13 when the electromagnetic coil 13 is energized.

[0019] like Figures 1-8 As shown, this utility model also discloses the following more optimized specific structures: Specifically, according to actual application needs, the first elastic element is a plurality of slotted permanent magnets 11 evenly distributed along the circumferential direction, and the second elastic element is a plurality of brake disc permanent magnets 12 installed in the brake disc 10 and evenly distributed along the circumferential direction. The magnetic poles of the slotted permanent magnets 11 near the corresponding brake disc 10 and the magnetic poles of the brake disc permanent magnets 12 near the slotted plate 5 have the same polarity (i.e., both are S poles or N poles); or, the first elastic element is a plurality of compression springs evenly distributed along the circumferential direction (not shown in the figure), and the second elastic element is an armature (not shown in the figure) installed between the brake disc 10 and the slotted plate 5.

[0020] In order to extend the normal service life and reduce the thickness of the entire product, the first elastic element is a plurality of slotted permanent magnets 11 evenly distributed along the circumference, and the second elastic element is a plurality of brake disc permanent magnets 12 installed in the brake disc 10 and evenly distributed along the circumference. The magnetic poles of the slotted permanent magnets 11 near the corresponding brake disc 10 and the magnetic poles of the brake disc permanent magnets 12 near the slot 5 have the same polarity.

[0021] In order to reduce the radial width of the slot 5 and achieve a larger hollow diameter, there are multiple electromagnetic coils 13 and they are evenly arranged along the circumferential direction. The multiple electromagnetic coils 13 and the multiple slot permanent magnets 11 are arranged along the circumferential direction of the same virtual circle.

[0022] To reduce the thickness of the slotted disc 5 while meeting functional requirements, thereby reducing the overall thickness and volume of the electromagnetic brake, and to facilitate separate control of the braking torque of the two brake discs 10 for better torque adjustment, multiple slotted disc permanent magnets 11 are respectively installed in multiple through holes (not marked in the figure) of the slotted disc 5. The magnetic poles of the multiple brake disc permanent magnets 12 in the two brake discs 10 that are closest to the slotted disc 5 have the same polarity as the corresponding magnetic poles of the slotted disc permanent magnets 11. Multiple recessed grooves (not marked in the figure) are provided on both sides of the slotted disc 5, and an electromagnetic coil 13 is installed in each of the recessed grooves. An electromagnetic coil 13 is installed between every two adjacent slotted disc permanent magnets 11. Multiple countersunk holes (not marked in the figure) are provided on the side surface of the brake disc 10 closest to the slotted disc 5, and a brake disc permanent magnet 12 is installed in each of the countersunk holes.

[0023] To further reduce the thickness of the slot 5, multiple electromagnetic coils 13 located on the same side of the slot 5 are arranged sequentially at intervals in the circumferential direction, and two adjacent electromagnetic coils 13 located on both sides of the slot 5 are staggered in the circumferential direction.

[0024] In order to increase the friction area between the brake disc 19 and the cover plate 2 without increasing the radial dimension to achieve a larger braking torque, and at the same time to achieve a larger hollow diameter to meet application requirements, an annular friction pad 9 is bonded to the side surface of the brake disc 10 near the corresponding cover plate 2. The side surface of the annular friction pad 9 near the corresponding cover plate 2 and the side surface of the cover plate 2 near the corresponding brake disc 10 are inclined planes 15 that are in mutual contact, and the inclined plane 15 has an angle of 60°-85° with the center line of the brake disc 10, preferably 75°-80°.

[0025] In order to further reduce the radial dimension occupied by the groove 5 and the brake disc 10 to achieve a larger hollow diameter, the brake disc 10 is provided with an L-shaped relief groove 14 near the outer wall of the groove 5, and the part of the groove 5 near the inner wall is placed in the relief groove 14 of the two brake discs 10.

[0026] To facilitate assembly and minimize the radial space and weight of the product, the edge of the slot 5 is provided with multiple slot connection lugs 7 that protrude outwards and are evenly distributed along the circumference. The edge of the cover plate 2 is provided with multiple cover plate connection lugs 3 that protrude outwards and are evenly distributed along the circumference. Multiple connecting screws 1 located on both sides of the slot 5 pass through the through holes on the multiple cover plate connection lugs 3 and are connected to the multiple screw holes on the multiple slot connection lugs 7.

[0027] Figure 1 and Figure 3 The image also shows a bushing 4 placed outside the connecting screw 1 and located between the cover plate 2 and the slotted plate 5; Figure 1 , Figure 2 , Figure 4 and Figure 5 It also shows a plurality of slot mounting lugs 6 provided on the edge of the slot 5 and protruding outward in the circumferential direction and evenly distributed in the circumferential direction, for mounting this electromagnetic brake; Figures 1-3 , Figures 6-8 Several keyways 8 are also shown on the inner circumferential wall of the brake disc 10, which form a circumferential transmission connection structure with the drive shaft (not shown in the figure) and are capable of axial movement; these structures are all conventional adaptive structures.

[0028] like Figures 1-8 As shown, in application, this electromagnetic brake is mounted on the relevant power components of the robot through multiple slotted mounting lugs 6, and forms a circumferential transmission connection structure with the drive shaft (such as the drive shaft connected to the motor shaft) through the keyway 8 of the brake disc 10, so that the brake disc 10 and the drive shaft can move axially relative to each other.

[0029] When the robot's power components need to be released from braking and operate normally, the electromagnetic coil 13 is energized to generate a magnetic field, which produces an electromagnetic attraction on the brake disc permanent magnet 12 and the brake disc 10. By controlling the magnitude of the current in the electromagnetic coil 13 or / and the number of energized electromagnetic coils 13, the electromagnetic attraction on the brake disc 10 is made just enough to overcome the permanent magnet repulsion between the multiple slotted permanent magnets 11 and the multiple brake disc permanent magnets 12, so that the brake disc 10 is located between the slotted plate 5 and the corresponding cover plate 2 with a gap, and the brake disc 10 can rotate freely synchronously with the drive shaft. At this time, the electromagnetic brake is in the released braking state.

[0030] When the robot's relevant power components need to stop rotating to complete timely braking, the electromagnetic field of the electromagnetic coil 13 disappears, and the electromagnetic attraction on the brake disc permanent magnet 12 and brake disc 10 disappears. The permanent magnetic repulsion between the multiple slotted permanent magnets 11 and the multiple brake disc permanent magnets 12 on both sides presses the brake disc 10 tightly against the corresponding cover plate 2. A strong frictional force is generated between the annular friction plate 9 and the corresponding cover plate 2, and the brake disc 10 can no longer rotate and stops quickly, driving the transmission shaft to stop synchronously. At this time, the electromagnetic brake is in the braking state.

[0031] In practical applications, the power components of a robot may require different braking torques to meet various functional needs. Therefore, it is necessary to adjust the braking torque. The wider the adjustment range and the more torque values, the broader its applicability. The braking torque adjustment principle of this invention is as follows: Multiple (six in the figure) electromagnetic coils 13 are installed on both sides of the slot 5. The power supply and current of each electromagnetic coil 13 can be controlled individually. When all electromagnetic coils 13 are de-energized, the braking torque corresponding to the total permanent magnetic repulsion between all the permanent magnets 11 of the slot and all the permanent magnets 12 of the brake discs on both sides is the initial braking torque. When the actual required braking torque is lower than the initial braking torque, some or all of the electromagnetic coils 13 can be energized and a suitable current can be set. At this time, the electromagnetic attraction generated by the energized electromagnetic coils 13 cannot completely overcome the total permanent magnetic repulsion, but it can cancel out a portion of it. Therefore, the friction between the annular friction pad 9 and the corresponding cover plate 2 decreases as the pressure on the brake disc 10 decreases, thereby reducing the actual braking torque. When the actual required braking torque is higher than the initial braking torque, some or all of the electromagnetic coils 13 can be reverse-energized and a suitable current can be set. At this time, the energized electromagnetic coils 13 generate electromagnetic repulsion on the brake disc 10 and the brake disc permanent magnet 12. This electromagnetic repulsion is superimposed on the total permanent magnet repulsion, causing the friction between the annular friction pad 9 and the corresponding cover plate 2 to increase as the pressure on the brake disc 10 increases, thereby increasing the actual braking torque.

[0032] The above embodiments are merely preferred embodiments of this utility model and are not intended to limit the technical solutions of this utility model. Any technical solution that can be implemented based on the above embodiments without creative effort should be considered to fall within the scope of protection of this utility model patent.

Claims

1. A portable electromagnetic brake with symmetrical structure, comprising a slot disc, a brake disc and a cover plate, the brake disc is located between the slot disc and the cover plate, an electromagnetic coil and a first elastic member are installed in the slot disc, characterized in that: There is one slot, and there are two brake discs and two cover plates. The two brake discs are located on the outer sides of the slot, and the two cover plates are located on the outer sides of the two brake discs. A second elastic member is installed inside the brake disc or between the brake disc and the slot. The second elastic member has a repulsive force with the first elastic member, and the second elastic member can generate an attractive force with the electromagnetic coil when the electromagnetic coil is energized.

2. The compact electromagnetic brake with symmetrical structure according to claim 1, characterized in that: The first elastic element is a plurality of slotted permanent magnets evenly distributed along the circumference, and the second elastic element is a plurality of brake disc permanent magnets installed inside the brake disc and evenly distributed along the circumference, wherein the magnetic poles of the slotted permanent magnets near the brake disc and the magnetic poles of the brake disc permanent magnets near the slots have the same polarity; or, the first elastic element is a plurality of compression springs evenly distributed along the circumference, and the second elastic element is an armature installed between the brake disc and the slots.

3. The portable electromagnetic brake with a symmetrical structure according to claim 2, characterized in that: The first elastic element is a plurality of slotted permanent magnets evenly distributed along the circumference, and the second elastic element is a plurality of brake disc permanent magnets installed in the brake disc and evenly distributed along the circumference. The magnetic poles of the slotted permanent magnets near the corresponding brake disc and the magnetic poles of the brake disc permanent magnets near the slots have the same polarity.

4. The portable electromagnetic brake with a symmetrical structure according to claim 3, characterized in that: The electromagnetic coils are multiple and evenly arranged along the circumference, and the multiple electromagnetic coils and the multiple slotted permanent magnets are arranged along the circumference of the same virtual circle.

5. The portable electromagnetic brake with a symmetrical structure according to claim 4, characterized in that: Multiple slotted permanent magnets are respectively installed in multiple through holes of the slotted plate. The magnetic poles of the multiple brake disc permanent magnets in the two brake discs are the same polarity as the corresponding magnetic poles of the slotted plate permanent magnets. Multiple recessed grooves are provided on both sides of the slotted plate, and an electromagnetic coil is installed in each recessed groove. An electromagnetic coil is installed between every two adjacent slotted plate permanent magnets. Multiple countersunk holes are provided on the side surface of the brake disc near the slotted plate, and a brake disc permanent magnet is installed in each countersunk hole.

6. The portable electromagnetic brake with a symmetrical structure according to claim 5, characterized in that: Multiple electromagnetic coils located on the same side of the slot are arranged sequentially at intervals in the circumferential direction, while two adjacent electromagnetic coils located on opposite sides of the slot are arranged in a staggered manner in the circumferential direction.

7. The portable electromagnetic brake with a symmetrical structure according to any one of claims 1-6, characterized in that: An annular friction pad is bonded to the side surface of the brake disc closest to the corresponding cover plate. The side surface of the annular friction pad closest to the corresponding cover plate and the side surface of the cover plate closest to the corresponding brake disc are inclined planes in mutual contact, and the inclined planes have an angle of 60°-85° with the center line of the brake disc.

8. The portable electromagnetic brake with a symmetrical structure according to any one of claims 1-6, characterized in that: The brake disc has an L-shaped relief groove on its outer wall near the groove, and the portion of the groove near the inner wall is placed in the relief groove of the two brake discs.

9. The portable electromagnetic brake with a symmetrical structure according to any one of claims 3-6, characterized in that: The edge of the slot is provided with a plurality of slot connection lugs that protrude outward in the circumferential direction and are evenly distributed along the circumferential direction. The edge of the cover plate is provided with a plurality of cover plate connection lugs that protrude outward in the circumferential direction and are evenly distributed along the circumferential direction. A plurality of connecting screws located on both sides of the slot are respectively connected to the plurality of screw holes on the plurality of cover plate connection lugs after passing through the through holes on the plurality of cover plate connection lugs.

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