A switching device

Abstract

This utility model discloses a switching device, relating to the field of contactor and relay technology. The switching device includes: a ceramic cover, a movable bracket disposed on the inner side of the ceramic cover, a support spring disposed on the top surface of the movable bracket, an active contact piece connected to the upper end of the support spring, an active contact at each end of the active contact piece, and two main stationary contacts passing through the top surface of the ceramic cover; magnets, two magnets disposed on both sides of the ceramic cover in a second direction; the active contacts include: an upper contact and a lower contact, the outer circumferential surface of the upper contact being a spherical upward arc-drawing surface; and the outer circumferential surface of the lower contact being a spherical first downward arc-drawing surface. The above-mentioned switching device solves the technical problems in existing relay contact assemblies where the arc-blocking groove between the moving contact and the moving contact piece has poor arc-drawing effect, the arc remains on the active contact piece for too long, aggravating electro-erosion of the moving contact, failing to effectively cut off the arc, and easily causing adverse extreme phenomena such as combustion and explosion.

Description

Technical Field

[0001] This utility model relates to the field of contactor and relay technology, and in particular to a switching device. Background Technology

[0002] In switching devices such as high-voltage contactors or relays, if the arc remains on the plane for too long, it exacerbates the erosion of the moving contacts. If the external magnetic field is insufficient or weakened, the product cannot effectively cut off the arc, leading to adverse extreme phenomena such as combustion and explosion.

[0003] However, on the one hand, the existing switchgear structure design is unreasonable. At the moment of contact between the active contact and the main stationary contact, a rigid collision may occur, affecting the service life of the switchgear. On the other hand, the surface of the moving contact in existing relay contact assemblies is mostly flat, or a raised moving contact is directly added to the flat surface of the active contact piece. Moreover, the arc-quenching groove set between the moving contact and the moving contact piece has a poor arc-initiating effect, and the arc remains on the active contact piece for too long, aggravating the electro-erosion of the moving contact, failing to effectively cut off the arc, and easily causing adverse extreme phenomena such as combustion and explosion. Therefore, an active contact piece and switchgear designed to solve the above problems are proposed. Utility Model Content

[0004] The purpose of this utility model is to provide a switching device that solves the technical problems of poor arc-initiating effect of the arc-blocking groove set between the moving contact and the moving contact piece in the existing relay contact assembly, the arc remaining on the moving contact piece for too long, aggravating the electro-erosion of the moving contact, failing to effectively cut off the arc, and being prone to adverse extreme phenomena such as combustion and explosion.

[0005] To achieve the above objectives, this utility model provides a switching device, comprising: a ceramic cover, a movable bracket disposed on the inner side of the ceramic cover, a support spring disposed on the top surface of the movable bracket, an active contact piece connected to the upper end of the support spring, an active contact being disposed at each end of the active contact piece, two main stationary contacts passing through the top surface of the ceramic cover, and the movable bracket being driven to reciprocate along a first direction to control the contact and separation of the active contacts and the main stationary contacts;

[0006] Two magnets are disposed on both sides of the ceramic cover in the second direction. When the active contact is separated from the main stationary contact, the two active contacts are respectively located at the center of the magnetic field generated by the magnets. The second direction is perpendicular to the first direction.

[0007] The active contact includes an upper contact and a lower contact, wherein the outer circumferential surface of the upper contact is a spherical upward-drawing arc surface; and the outer circumferential surface of the lower contact is a spherical first downward-drawing arc surface.

[0008] Preferably, an insulating pad is provided on the top surface of the active contact piece, and an insulating base is provided on the top surface of the insulating pad. The insulating base includes a base body, and auxiliary moving springs are respectively provided at both ends of the base body in a third direction. The two auxiliary moving springs are integrally formed, and auxiliary moving contacts are provided at the ends of the auxiliary moving springs. Two lead terminals are provided on the top surface of the ceramic cover, and auxiliary stationary contacts are respectively provided at the lower ends of the two lead terminals. The two auxiliary stationary contacts are respectively located above the corresponding auxiliary moving contacts.

[0009] Preferably, the top surface of the insulating gasket is provided with an assembly hole, a rivet is inserted into the assembly hole, and an mounting plate is sleeved on the outer peripheral side of the upper end of the rivet, the mounting plate being connected to the base.

[0010] Preferably, the top surface of the active contact piece is provided with a first mounting groove for accommodating the lower end of the rivet, and the top surface of the base is provided with a second mounting groove for accommodating the mounting plate, and the mounting plate is fixed in the second mounting groove by screws.

[0011] Preferably, the bottom surface of the active contact piece is provided with an insulating limiting plate, the insulating limiting plate is U-shaped in general, the active contact piece is snapped into the top surface of the insulating limiting plate, the bottom surface of the insulating limiting plate is provided with a through hole for a support spring to pass through, the through hole and the limiting protrusion combine to form a first limiting groove, and the upper end of the support spring is snapped into the first limiting groove.

[0012] Preferably, the bottom surface of the active contact piece is provided with a limiting protrusion, the top surface of the movable bracket is provided with a second limiting groove, the limiting protrusion is engaged with the upper end of the support spring, and the second limiting groove is engaged with the lower end of the support spring.

[0013] Preferably, the top surface of the upper contact and the bottom surface of the lower contact are both planes, the top surface of the upper contact protrudes beyond the top surface of the active contact piece in a first direction, and the bottom surface of the lower contact is coplanar with the bottom surface of the active contact piece.

[0014] Preferably, the two upper contacts are respectively provided with arc-blocking grooves on the side facing the center of the active contact piece, and a first transition arc-leading surface is provided at the connection position between the arc-blocking groove and the upper contact; the active contact piece is provided with a second lower arc-leading surface at the lower part of the two end faces in the third direction, and a second transition arc-leading surface is provided at the connection position between the second lower arc-leading surface and the first lower arc-leading surface.

[0015] Preferably, the active contact piece has two arc-shaped surfaces on its two ends in the third direction. The arc-shaped surfaces include: a first arc-shaped segment and a second arc-shaped segment that are smoothly connected. The first arc-shaped segment is adapted to the first transition arc-shaped surface, and the second arc-shaped segment is adapted to the second lower arc-shaped surface.

[0016] Preferably, the curvature of the first arc segment is greater than that of the second arc segment, and the tangent at one end of the second arc segment near the side of the active contact is perpendicular to the second direction.

[0017] Compared with the above-mentioned background technology, the switch electrical appliance provided by this utility model has the following beneficial effects:

[0018] (1) This utility model provides elastic support for the active contact piece by a support spring. When the active contact abuts against the main stationary contact, the support spring will be compressed and contracted to a certain length to avoid rigid collision between the active contact and the main stationary contact, thereby protecting the active contact and the main stationary contact and extending the service life of the overall switchgear.

[0019] (2) In this utility model, the ceramic cover is provided with magnets on both sides in the second direction. When the active contact is separated from the main stationary contact, the two active contacts are located at the center of the magnetic field generated by the magnets. At this time, the large magnetic field force at the separation position of the active contact and the main stationary contact can generate a large Lorentz force on the arc, further increasing the bending amplitude of the arc formed by the magnetic blow-out, and the arc is easier to extinguish.

[0020] (3) In this utility model, the active contact includes an upper contact and a lower contact. The outer circumferential surface of the upper contact is a spherical upper arc surface, and the outer circumferential surface of the lower contact is a spherical first lower arc surface. From the top surface of the upper contact to the bottom surface of the lower contact, the diameter of the active contact first increases and then decreases. When the active contact is separated from the main stationary contact, the electric arc can be quickly pulled from the upper contact through the upper arc surface and the first lower arc surface to the lower surface of the active contact piece and the space below the active contact piece, increasing the movement speed of the electric arc on the surface of the active contact, accelerating the separation of the electric arc between the active contact and the main stationary contact, preventing other parts from being burned by the electric arc to a certain extent, and reducing the voltage erosion of the active contact, accelerating the arc extinguishing speed, thereby greatly reducing the erosive effect of the electric arc on the active contact piece. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0022] Figure 1 A three-dimensional structural diagram of the switching device provided in the embodiment of this utility model;

[0023] Figure 2 for Figure 1 Schematic diagram of the cross section at point AA;

[0024] Figure 3 for Figure 1 Schematic diagram of the cross section at point BB;

[0025] Figure 4 A three-dimensional structural diagram of the active contact piece provided in an embodiment of this utility model;

[0026] Figure 5 A side view of the active contact provided in an embodiment of this utility model;

[0027] Figure 6 A top view of the active contact piece provided in an embodiment of this utility model;

[0028] Figure 7 This is an assembly diagram of the movable support and insulating base provided in an embodiment of the present utility model;

[0029] Figure 8 This is an exploded view of the insulating base provided in an embodiment of the present invention;

[0030] Figure 9 An exploded view of the insulating base provided in an embodiment of this utility model from another angle;

[0031] Figure 10 for Figure 2 Enlarged view of point C in the middle;

[0032] Figure 11 for Figure 3 Enlarged view of point D in the middle;

[0033] Figure 12 This is a top view of the interior of the switching device provided in an embodiment of the present utility model.

[0034] Specifically, 1-Ceramic cover; 101-Inner protrusion; 102-End space; 103-Middle space; 2-Moving bracket; 201-Support spring; 202-First limiting groove; 3-Active contact piece; 301-Second limiting groove; 302-First assembly groove; 303-Limiting protrusion; 4-Active contact; 401-Upper contact; 402-Upper arc-drawing surface; 403-Lower contact; 404-First lower arc-drawing surface; 5-Arc-isolating groove; 6-First transition arc-drawing surface; 7-Second lower arc-drawing surface; 8-Second transition arc-drawing surface; 9-Curved surface; 901 - First arc segment; 902 - Second arc segment; 10 - Main stationary contact; 11 - Electromagnetic system; 1101 - Push-pull rod; 12 - Insulating gasket; 1201 - Extension; 1202 - Assembly hole; 13 - Insulating base; 1301 - Base; 1302 - Auxiliary moving spring; 1303 - Auxiliary moving contact; 1304 - Second assembly slot; 14 - Lead terminal; 1401 - Auxiliary stationary contact; 15 - Magnet; 16 - Connecting bracket; 17 - Rivet; 18 - Mounting plate; 19 - Insulating limiting plate; 20 - Tangent; 21 - Straight edge. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0036] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] like Figure 1 , Figure 2 and Figure 3 As shown, to achieve the above objectives, this utility model provides a switching device, including: a ceramic cover 1 and a magnet 15. The inner side of the ceramic cover 1 forms a sealed cavity, and a movable support 2 is disposed within the sealed cavity. A support spring 201 is disposed on the top surface of the movable support 2. The upper end of the support spring 201 is connected to an active contact piece 3. An active contact 4 is disposed at each end of the active contact piece 3. Two main stationary contacts 10 are disposed on the top surface of the ceramic cover 1. The two active contacts 4 are respectively located directly above one of the main stationary contacts 10. The movable support 2 can be driven to reciprocate along a first direction, wherein the first direction is the adjacent... Figure 1The Z-direction is used to control the contact and separation of the active contact 4 and the main stationary contact 10. The active contact piece 3 is elastically supported by the support spring 201. When the active contact 4 abuts against the main stationary contact 10, the support spring 201 will be compressed and contracted to a certain length to avoid rigid collision between the active contact 4 and the main stationary contact 10, thereby protecting the active contact 4 and the main stationary contact 10 and extending the service life of the overall switchgear.

[0038] Magnets 15 are respectively provided on both sides of the ceramic cover 1 in the second direction. When the active contact 4 separates from the main stationary contact 10, the two active contacts 4 are respectively located at the center of the magnetic field generated by the magnets 15. At this time, the large magnetic force at the separation position of the active contact 4 and the main stationary contact 10 can generate a large Lorentz force on the arc, further increasing the bending amplitude of the arc caused by magnetic blow-out, making the arc easier to extinguish. Among them, the second direction is Figure 1 In the X direction, the second direction is perpendicular to the first direction.

[0039] like Figure 4 , Figure 5 and Figure 6 As shown, the active contact 4 includes an upper contact 401 and a lower contact 403. The outer circumferential surface of the upper contact 401 is an upward arc surface 402, which is spherical in shape. The outer circumferential surface of the lower contact 403 is a first downward arc surface 404, which is also spherical in shape. The upward arc surface 402 and the first downward arc surface 404 are smoothly connected. Therefore, from the top surface of the upper contact 401 to the bottom surface of the lower contact 403, the diameter of the active contact 4 first increases and then decreases. When the stationary contact 10 breaks, the electric arc can be quickly drawn from the upper contact 401 through the upper arc-leading surface 402 and the first lower arc-leading surface 404 to the lower surface of the active contact 3 and the space below the active contact 3. This increases the movement speed of the electric arc on the surface of the active contact 4, accelerates the separation of the electric arc between the active contact 4 and the main stationary contact 10, and to a certain extent prevents other parts from being burned by the electric arc. It can also reduce the voltage erosion of the active contact 4 and accelerate the arc extinguishing speed, thereby greatly reducing the erosive effect of the electric arc on the active contact 3.

[0040] like Figure 7 , Figure 8 and Figure 9 As shown, in some embodiments of this utility model, an insulating pad 12 is provided on the top surface of the active contact 3, and an insulating base 13 is provided on the top surface of the insulating pad 12. The insulating base 13 includes a base 1301, and auxiliary moving springs 1302 are respectively provided at both ends of the base 1301 in a third direction. The two auxiliary moving springs 1302 are integrally formed, and auxiliary moving contacts 1303 are provided at the ends of the auxiliary moving springs 1302. Wherein, the second direction is... Figure 1In the Y direction, the third direction is perpendicular to the first and second directions, respectively. Further, two lead terminals 14 are provided on the top surface of the ceramic cover 1, and auxiliary stationary contacts 1401 are respectively provided at the lower ends of the two lead terminals 14. The two auxiliary stationary contacts 1401 are located above the corresponding auxiliary moving contacts 1303. When the circuit is connected, the control electromagnetic system 11 drives the push-pull rod 1101 to move the moving bracket 2 closer to the main stationary contact piece along the first direction. Before the active contact 4 abuts against the main stationary contact 10, the auxiliary moving contact 1303 first contacts the auxiliary stationary contact 1401 to connect the capacitive load. The control electromagnetic system 11 continues to drive the push-pull rod 1101 to move the moving bracket 2 closer to the main stationary contact piece along the first direction until the main contact piece abuts against the stationary contact piece to connect to the main circuit. This allows the auxiliary contact piece assembly to connect the capacitive load first, resolving the influence of the capacitive load and preventing it from affecting the contact resistance after the main contact piece is connected to the main circuit, effectively increasing the stability of the contact resistance.

[0041] like Figure 3 , Figure 10 and Figure 11 As shown, in some embodiments of this utility model, two connecting brackets 16 are symmetrically arranged on the top surface of the movable bracket 2. The upper part of the connecting bracket 16 is provided with a socket. The insulating pad 12 is provided with extensions 1201 at both ends in the third direction. The extensions 1201 are inserted into the sockets. The insulating pad 12 is fixed by the two connecting brackets 16. With the support spring 201 supporting the active contact 3, the insulating pad 12 is stably fixed on the top surface of the active contact 3.

[0042] In addition, the top surface of the insulating gasket 12 is provided with an assembly hole 1202, and a rivet 17 is inserted into the assembly hole 1202. The outer peripheral side of the upper end of the rivet 17 is fitted with an mounting plate 18. The top surface of the active contact piece 3 is provided with a first assembly groove 302 for accommodating the lower end of the rivet 17. The top surface of the base 1301 is provided with a second assembly groove 1304 for accommodating the mounting plate 18. The bottom surface of the mounting plate 18 is attached to the bottom surface of the second assembly groove 1304, and the mounting plate 18 is fixed in the second assembly groove 1304 by screws, thereby fixing the base 1301 to the top surface of the insulating gasket 12.

[0043] It should be noted that the bottom surface of the active contact 3 is provided with a limiting protrusion 303, and the top surface of the movable bracket 2 is provided with a first limiting groove 202. The limiting protrusion 303 is engaged with the upper end of the support spring 201, and the first limiting groove 202 is engaged with the lower end of the support spring 201. The design of the limiting protrusion 303 and the first limiting groove 202 can stably limit the two ends of the support spring 201 to ensure the stability of the active contact 3 when it reciprocates in the first direction, thereby ensuring that the switch can stably control the circuit to turn on or off.

[0044] Optionally, an insulating limiting plate 19 is provided on the bottom surface of the active contact 3. The insulating limiting plate 19 is U-shaped, and the active contact 3 is snapped into the top surface of the insulating limiting plate 19. At the same time, a through hole is provided on the bottom surface of the insulating limiting plate 19 for the support spring 201 to pass through. The through hole and the limiting protrusion 303 combine to form a second limiting groove 301, and the upper end of the support spring 201 is stably snapped into the second limiting groove 301. At the same time, through the cooperation of the insulating limiting plate 19 and the insulating gasket 12, the active contact 3 can be isolated from other components, thus protecting the overall switching device.

[0045] like Figure 4 and Figure 5 As shown, in some embodiments of this utility model, the top surface of the upper contact 401 and the bottom surface of the lower contact 403 are both planes, and the top surface of the upper contact 401 protrudes beyond the top surface of the active contact 3 in the first direction. That is, the top surface of the upper contact 401 protrudes by a height H compared to the top surface of the active contact 3. The bottom surface of the lower contact 403 is coplanar with the bottom surface of the active contact 3. This can increase the length and tilt angle of the upper arc-drawing surface 402, thereby increasing the traction effect on the electric arc and accelerating the creepage speed of the electric arc, thus accelerating the arc extinguishing speed and significantly reducing the erosive effect of the electric arc on the active contact 3.

[0046] An arc-blocking groove 5 is provided on the side of the upper contact 401 facing the center of the active contact 3. The arc-blocking groove 5 is used to separate the active contact 3 from the upper contact 401. The arc-blocking groove 5 is arc-shaped and is designed around the circumferential outer side of the upper contact 401. A first transition arc-leading surface 6 is provided at the connection position between the arc-blocking groove 5 and the upper contact 401. The first transition arc-leading surface 6 forms an arc guiding path, guiding the arc in the arc-blocking groove 5 to move quickly towards the second transition arc-leading surface 8 and the second lower arc-leading surface 7.

[0047] In addition, a second lower arc-inducing surface 7 is provided at the lower part of the two ends of the active contact 3 in the third direction. A second transition arc-inducing surface 8 is provided at the junction of the second lower arc-inducing surface 7 and the first lower arc-inducing surface 404. The first transition arc-inducing surface 6, the first lower arc-inducing surface 404, the second transition arc-inducing surface 8 and the second lower arc-inducing surface 7 form a complete arc-inducing path, which facilitates the rapid creep of the arc from the arc-isolating groove 5 and the lower contact 403, further accelerating the arc extinguishing speed, thereby greatly reducing the erosive effect of the arc on the active contact 3.

[0048] It should be noted that, compared with the traditional active contact 3 structure design, the active contact 3 structure in this utility model is simple. It does not require the installation of a first arc-blocking component on the stationary contact head, nor does it require the installation of a second arc-blocking component under the active contact 3 for arc blocking and arc extinguishing. The overall structure is simple and the assembly process is simpler.

[0049] In some embodiments of this utility model, the active contact 3 has two arc-shaped surfaces 9 on its two ends in the third direction. The arc-shaped surfaces 9 include a first arc-shaped segment 901 and a second arc-shaped segment 902 that are smoothly connected. The first arc-shaped segment 901 is adapted to the first transition arc-leading surface 6, and the second arc-shaped segment 902 is adapted to the second lower arc-leading surface 7. Simultaneously, the curvature of the first arc-shaped segment 901 is greater than the curvature of the second arc-shaped segment 902, and the tangent 20 at one end of the second arc-shaped segment 902 near the side of the active contact 3 is perpendicular to the second direction. The electric arc in the arc-isolating groove 5 extends towards the second transition arc-leading surface. 8. While the second lower arc-drawing surface 7 moves rapidly, the arc-shaped structure design of the edge of the active contact 3 allows the arc to be drawn towards the inner side of the ceramic cover 1 via the first arc segment 901 and the second arc segment 902. Compared to the traditional structure design of the straight edge 21 in the active contact 3, the arc moves closer to the magnet 15 at the end of the second arc segment 902 near the inner side of the ceramic cover 1. This results in a stronger magnetic force on the arc when it approaches the magnet 15, a greater bending amplitude caused by the magnetic blow-out, and easier arc extinguishing, thus significantly improving the arc extinguishing efficiency. It also prevents the arc from rushing towards the auxiliary end in the middle of the ceramic cover 1, effectively preventing the arc from damaging the auxiliary end of the central space 103 through creepage.

[0050] like Figure 12 As shown, in some embodiments of this utility model, a sealed cavity is formed on the inner side of the ceramic cover 1. Two inner protrusions 101 are respectively provided on both sides of the inner side of the ceramic cover 1 in the third direction. The four inner protrusions 101 are respectively located on both sides of the first plate in the second direction. The four inner protrusions 101 divide the internal space of the ceramic cover 1 into an end space 102 and a middle space 103. The end space 102 is the space for active contact arc ignition and arc extinguishing, and the middle space 103 is the space for arc creepage of auxiliary moving contact 1303. By separating the active contact arc ignition space and the auxiliary moving contact 1303 arc creepage space, the high voltage and current of the end space 102 can be effectively prevented from damaging the low voltage of the middle space 103 through creepage.

[0051] In summary, when the active contact 4 and the main stationary contact 10 are disconnected, the electric arc can be quickly drawn from the upper contact 401 through the upper arc-leading surface 402 and the first lower arc-leading surface 404 to the lower surface of the active contact piece 3 and the space below the active contact piece 3. This increases the movement speed of the electric arc on the surface of the active contact 4, accelerates the separation of the electric arc between the active contact 4 and the main stationary contact 10, and to a certain extent prevents other parts from being burned by the electric arc. It can also reduce the voltage erosion of the active contact 4 and accelerate the arc extinguishing speed, thereby significantly reducing the erosive effect of the electric arc on the active contact piece 3.

[0052] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0053] This article uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principles of this utility model, and these improvements and modifications also fall within the protection scope of this utility model.

Claims

1. A switching device, characterized in that, include: A ceramic cover has a movable support on its inner side and a support spring on its top surface. The upper end of the support spring is connected to an active contact piece, and each of the two ends of the active contact piece is provided with an active contact. Two main stationary contacts are passed through the top surface of the ceramic cover. The movable support can be driven to reciprocate along a first direction to control the contact and separation of the active contacts and the main stationary contacts. Two magnets are disposed on both sides of the ceramic cover in the second direction. When the active contact is separated from the main stationary contact, the two active contacts are respectively located at the center of the magnetic field generated by the magnets. The second direction is perpendicular to the first direction. The active contact includes an upper contact and a lower contact, wherein the outer circumferential surface of the upper contact is a spherical upward-drawing arc surface; and the outer circumferential surface of the lower contact is a spherical first downward-drawing arc surface.

2. A switching device according to claim 1, characterized in that, An insulating pad is provided on the top surface of the active contact piece, and an insulating base is provided on the top surface of the insulating pad. The insulating base includes a base body, and auxiliary moving springs are respectively provided at both ends of the base body in a third direction. The two auxiliary moving springs are integrally formed, and auxiliary moving contacts are provided at the ends of the auxiliary moving springs. Two lead terminals are provided on the top surface of the ceramic cover, and auxiliary stationary contacts are respectively provided at the lower ends of the two lead terminals. The two auxiliary stationary contacts are respectively located above the corresponding auxiliary moving contacts.

3. A switching device according to claim 2, characterized in that, The top surface of the insulating gasket is provided with an assembly hole, a rivet is inserted into the assembly hole, and an mounting plate is sleeved on the outer peripheral side of the upper end of the rivet. The mounting plate is connected to the base.

4. A switching device according to claim 3, characterized in that, The top surface of the active contact piece is provided with a first mounting groove for accommodating the lower end of the rivet, and the top surface of the base is provided with a second mounting groove for accommodating the mounting plate. The mounting plate is fixed in the second mounting groove by screws.

5. A switching device according to claim 1, characterized in that, An insulating limiting plate is provided on the bottom surface of the active contact piece. The insulating limiting plate is U-shaped. The active contact piece is snapped into the top surface of the insulating limiting plate. A through hole is provided on the bottom surface of the insulating limiting plate. The through hole is used to pass through the support spring. The through hole and the limiting protrusion combine to form a first limiting groove. The upper end of the support spring is snapped into the first limiting groove.

6. A switching device according to claim 1, characterized in that, The bottom surface of the active contact piece is provided with a limiting protrusion, and the top surface of the movable bracket is provided with a second limiting groove. The limiting protrusion is engaged with the upper end of the support spring, and the second limiting groove is engaged with the lower end of the support spring.

7. A switching device according to claim 1, characterized in that, The top surface of the upper contact and the bottom surface of the lower contact are both planes. The top surface of the upper contact protrudes beyond the top surface of the active contact in a first direction, and the bottom surface of the lower contact is coplanar with the bottom surface of the active contact.

8. A switching device according to claim 1, characterized in that, The two upper contacts are respectively provided with arc-blocking grooves on the side facing the center of the active contact piece, and a first transition arc-leading surface is provided at the connection position between the arc-blocking groove and the upper contact; the active contact piece is provided with a second lower arc-leading surface at the lower part of the two end faces in the third direction, and a second transition arc-leading surface is provided at the connection position between the second lower arc-leading surface and the first lower arc-leading surface.

9. A switching device according to claim 8, characterized in that, The active contact piece has two arc-shaped surfaces on its two ends in the third direction. The arc-shaped surfaces include a first arc-shaped segment and a second arc-shaped segment that are smoothly connected. The first arc-shaped segment is adapted to the first transition arc-leading surface, and the second arc-shaped segment is adapted to the second lower arc-leading surface.

10. A switching device according to claim 9, characterized in that, The curvature of the first arc segment is greater than that of the second arc segment, and the tangent at one end of the second arc segment near the side of the active contact is perpendicular to the second direction.

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