Arc extinguishing exhaust system of circuit breaker

Abstract

The utility model discloses a breaker arc extinguishing exhaust system, which comprises an arc extinguishing chamber body, and a plurality of upper exhaust holes and a plurality of lower exhaust holes which are arranged at the rear end of the arc extinguishing chamber body in a vertically staggered manner, a shell is internally provided with a plurality of groups of partition plate structures which divide an exhaust area into a plurality of exhaust channels, and the plurality of exhaust channels are communicated with the upper exhaust holes and the lower exhaust holes. According to the structure that the partition plate is composed of the upper partition rib and the lower partition rib which abut against each other up and down, in order to avoid the upper exhaust hole and the lower exhaust hole, the staggered parts which are partially overlapped and extend in a staggered mode are arranged between the upper partition rib and the lower partition rib, and the structural layout between the partition ribs and the exhaust holes is reasonably optimized, so that the upper exhaust hole and the lower exhaust hole are prevented from being blocked by the upper partition rib and the lower partition rib; according to the utility model, the arc extinguish chamber body is provided with the plurality of exhaust channels, so that the exhaust smoothness of the arc extinguish chamber body is ensured, the temperature rise and pressure in the arc extinguish chamber are reduced, the explosion risk is reduced, and the electrical insulation performance among the plurality of exhaust channels is realized, thereby improving the arc extinguish capacity and breaking capacity of the product.

Description

Technical Field

[0001] The utility model relates to the technical field of low-voltage electrical appliances, in particular to an arc extinguishing exhaust system for a circuit breaker. Background Art

[0002] The arc extinguishing system is an important component of a small circuit breaker, and its function is to extinguish the arc generated on the contact system. The arc extinguishing system of the existing small circuit breaker mainly includes an arc extinguishing chamber, an arc striking structure and an exhaust channel. The arc extinguishing chamber includes an arc extinguishing cover and a plurality of arc extinguishing grids arranged in parallel in the arc extinguishing cover. The rear end of the arc extinguishing chamber is provided with a plurality of exhaust ports staggered up and down. In order to smoothly discharge the arc extinguishing gas to the outside of the circuit breaker, a plurality of exhaust channels connected to the rear of the arc extinguishing chamber are provided in the circuit breaker housing, so that the exhaust port is connected to the exhaust channel. An insulating partition is provided between the plurality of exhaust channels, and the plurality of exhaust channels are separated from each other by the insulating partition to improve the electrical insulation performance. Since one end of the insulating partition is in contact with the rear end of the arc extinguishing chamber, it will block some of the staggered exhaust ports, which will cause poor exhaust or even blockage of the gas in the arc extinguishing chamber, causing the gas temperature and pressure in the arc extinguishing chamber to increase, affecting the breaking capacity of the circuit breaker, and seriously causing the arc extinguishing chamber to explode. Utility Model Content

[0003] The technical problem to be solved by the utility model is to overcome the problem in the prior art that the insulating partition abuts against the rear end of the arc extinguishing chamber, which blocks some staggered exhaust ports, resulting in poor exhaust or even blockage of gas inside the arc extinguishing chamber, which may seriously cause the arc extinguishing chamber to explode and affect the breaking capacity of the circuit breaker.

[0004] In order to solve the above technical problems, the utility model provides a circuit breaker arc extinguishing exhaust system, including an arc extinguishing device arranged in a shell and an exhaust area connected to the rear of the arc extinguishing device, the arc extinguishing device including an arc extinguishing chamber body and an arc extinguishing plate group arranged in the arc extinguishing chamber body, the front end of the arc extinguishing chamber body is an open end, and the rear end of the arc extinguishing chamber body is provided with a plurality of upper exhaust holes and a plurality of lower exhaust holes arranged staggered up and down, and the shell is provided with a plurality of groups of partition structures that separate the exhaust area into a plurality of exhaust channels, each group of partition structures includes an upper partition rib and a lower partition rib that are abutted against each other up and down, and a staggered portion that partially overlaps and extends staggered with each other is provided between the upper partition rib and the lower partition rib, so that the staggered portion of the upper partition rib extends and abuts against the rear end of the arc extinguishing chamber body and is located between two of the upper exhaust holes, and the staggered portion of the lower partition rib extends and abuts against the rear end of the arc extinguishing chamber body and is located between two of the lower exhaust holes.

[0005] As a preferred embodiment, the offset portion includes an overlapping area formed between the upper partition rib and the lower partition rib, an upper offset area formed at the top of the upper partition rib and located on one side of the overlapping area, and a lower offset area formed at the bottom of the lower partition rib and located on the other side of the overlapping area, and the upper offset area and the lower offset area are offset up and down.

[0006] As a preferred solution, the upper partition rib and the lower partition rib are arranged in a bent shape and extend in the housing. A dislocation part is provided in the first half section of the upper partition rib and the lower partition rib close to the arc extinguishing chamber body, and they are offset and abutted against each other up and down. The second half section of the upper partition rib and the lower partition rib far from the arc extinguishing chamber body overlap and abut against each other up and down.

[0007] As a preferred solution, the housing includes a housing base and a housing cover. The upper partition rib and the lower partition rib are respectively arranged on the housing base and the housing cover. Two sets of the partition structures are provided in the exhaust area of the housing. The exhaust area includes three exhaust channels formed by separating the two sets of partition structures.

[0008] As a preferred solution, the three exhaust channels are respectively an upper exhaust channel, a middle exhaust channel and a lower exhaust channel which are sequentially and spacedly distributed at the rear end of the arc extinguishing chamber body. An air outlet structure communicating with the three exhaust channels is provided on the housing.

[0009] As a preferred solution, a terminal groove for installing a terminal is provided on the housing, and a partition strip is arranged between the terminal groove and the exhaust area. The air outlet structure includes a first air hole provided on the partition strip and communicating the terminal groove with the upper exhaust channel.

[0010] As a preferred solution, the air outlet structure includes an air outlet buffer area provided at the ends of the middle exhaust channel and the lower exhaust channel, a second air hole provided at one end of the housing and communicating with the air outlet buffer area, and a third air hole provided at the bottom of the housing and communicating with the air outlet buffer area.

[0011] As a preferred solution, an arc ignition channel is provided in the housing and connected between the contact structure and the front end of the arc extinguishing chamber body. Two arc ignition members are arranged on both sides of the arc ignition channel. A plurality of arc-shaped arc dividing and guiding grooves are formed at intervals in the middle of the arc ignition channel.

[0012] The technical solution of the present utility model has the following advantages compared with the prior art:

[0013] 1. In the arc extinguishing exhaust system of the circuit breaker provided by the utility model, the upper and lower exhaust holes are arranged at the rear end of the arc extinguishing chamber body in an up-and-down staggered arrangement, and multiple exhaust channels are separated in the exhaust area by multiple groups of partition structures. The multiple exhaust channels are all connected to the exhaust holes, so that the arc extinguishing gas is discharged out of the shell through the multiple exhaust channels. In this way, the gas can be dispersed to reduce the gas energy, effectively avoid the reignition of the arc gas, and reduce the internal temperature rise of the product. According to the partition structure, it is composed of upper partition ribs and lower partition ribs that are matched with each other up and down. In order to avoid the upper and lower exhaust holes, a part is provided between the upper and lower partition ribs. The overlapping and mutually staggered extending offset portions, during installation, allow the offset portion of the upper partition rib to extend and abut between any two upper exhaust holes at the rear end of the arc extinguishing chamber body, and allow the offset portion of the lower partition rib to extend and abut between any two upper exhaust holes at the rear end of the arc extinguishing chamber body. By reasonably optimizing the structural layout between the partition ribs and the exhaust holes, this design avoids the upper and lower partition ribs blocking the upper and lower exhaust holes, so as to ensure the smooth exhaust of the arc extinguishing chamber body, which is beneficial to reducing the temperature rise and pressure in the arc extinguishing chamber, reducing the risk of explosion, and achieving electrical insulation performance between adjacent exhaust channels, thereby improving the arc extinguishing ability and breaking capacity of the product.

[0014] 2. In the arc extinguishing exhaust system of the circuit breaker provided by the utility model, three exhaust channels are formed by separating the exhaust area through two groups of partition structures, and an outlet structure connecting the three exhaust channels is provided on the shell. The advantage of such a design is that since the partition structure avoids the exhaust hole at the rear end of the arc extinguishing chamber body, the arc extinguishing gas is evenly discharged from the upper and lower exhaust holes at the rear end of the arc extinguishing chamber, and the arc extinguishing gas is separated and flowed through the three exhaust channels for exhaust. In this way, the residual arc and gas can be divided at this distance in the exhaust area, and the pressure in the arc extinguishing chamber and the exhaust area and the energy of the charged free gas can be quickly reduced, thereby reducing the possibility of reignition of charged gas or arc, and ensuring the safety of product use.

[0015] 3. In the arc extinguishing exhaust system of the circuit breaker provided by the utility model, according to the three exhaust channels, namely the upper exhaust channel, the middle exhaust channel and the lower exhaust channel connected to the rear end of the arc extinguishing chamber body, the charged gas is divided and diverted through the upper exhaust channel, the middle exhaust channel and the lower exhaust channel, so as to reduce the energy of the charged gas. With this structural arrangement, the gas discharged through the upper exhaust channel will eventually be discharged to the outside from the terminal slot position through the first exhaust hole, and the gas discharged through the middle exhaust channel and the lower exhaust channel will be discharged to the outside through the second exhaust hole and the third exhaust hole, thereby reducing the pressure in the shell, avoiding the occurrence of explosion, and making it safer to use. Such a design forms multiple exhaust paths on the shell. During normal use, outside air can enter the product through multiple exhaust ports, and perform heat exchange or heat convection with the high-temperature air in the product, thereby reducing the internal temperature of the product, which has the effect of reducing temperature rise and product power consumption. Brief Description of the Drawings

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art.

[0017] Figure 1 It is a schematic plan view of the arc extinguishing and exhaust system of the circuit breaker of the present invention;

[0018] Figure 2 It is a schematic plan view of the arc extinguishing and exhaust system of the circuit breaker of the present invention;

[0019] Figure 3 It is a schematic sectional view of the arc extinguishing and exhaust system of the circuit breaker of the present invention;

[0020] Figure 4 is Figure 3 A partial enlarged schematic view of the partition structure shown.

[0021] Description of the reference numerals: 1. Housing; 11. Terminal slot; 2. Arc extinguishing chamber body; 21. Upper exhaust hole; 22. Lower exhaust hole; 3. Partition structure; 31. Upper partition rib; 32. Lower partition rib; 4. Misalignment part; 41. Upper misalignment area; 42. Lower misalignment area; 5. Exhaust passage; 51. Upper exhaust passage; 52. Middle exhaust passage; 53. Lower exhaust passage; 54. Exhaust buffer area; 61. First air outlet hole; 62. Second air outlet hole; 63. Third air outlet hole; 7. Arc ignition passage; 8. Arc ignition part; 91. Moving contact; 92. Static contact. Specific Embodiments

[0022] The following will clearly and completely describe the technical solutions of the present invention with reference to the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] In the description of the present invention, it should be noted that the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] Example

[0026] This embodiment provides Figures 1-4 The circuit breaker arc extinguishing exhaust system shown in the figure comprises an arc extinguishing device arranged in a housing 1 and an exhaust area connected to the rear of the arc extinguishing device, wherein the arc extinguishing device comprises an arc extinguishing chamber body 2 and an arc extinguishing sheet group arranged in the arc extinguishing chamber body 2, wherein the front end of the arc extinguishing chamber body 2 is an open end, and the rear end of the arc extinguishing chamber body 2 is provided with a plurality of upper exhaust holes 21 and a plurality of lower exhaust holes 22 arranged in an up-and-down staggered manner, and the housing 1 is provided with a plurality of baffle structures 3 for dividing the exhaust area into a plurality of exhaust channels 5, and each baffle structure 3 ... The plate structure 3 includes an upper partition rib 31 and a lower partition rib 32 which are connected to each other from top to bottom. A dislocation portion 4 which partially overlaps and extends staggered from each other is provided between the upper partition rib 31 and the lower partition rib 32. The dislocation portion 4 includes one end of the upper partition rib 31 and the lower partition rib 32, so that the dislocation portion 4 of the upper partition rib 31 extends to abut against the rear end of the arc extinguishing chamber body 2 and is located between two of the upper exhaust holes 21, and the dislocation portion 4 of the lower partition rib 32 extends to abut against the rear end of the arc extinguishing chamber body 2 and is located between two of the lower exhaust holes 22.

[0027] The above implementation is the core technical solution of this embodiment. Multiple exhaust channels 5 are formed in the exhaust area by dividing multiple groups of partition structures 3. The multiple exhaust channels 5 are all connected to the exhaust holes, so that the arc extinguishing gas is diverted and discharged outside the shell 1 through the multiple exhaust channels 5. In this way, the gas can be dispersed to reduce the gas energy, effectively avoid the reignition of the arc gas, and reduce the temperature rise inside the product. The partition structure 3 is composed of an upper partition rib 31 and a lower partition rib 32 that are matched with each other. In order to avoid the upper and lower exhaust holes, a partially overlapping and mutually staggered offset is provided between the upper and lower partition ribs 32. Part 4, when installed, the offset part 4 of the upper partition rib 31 is extended to abut between the two upper exhaust holes 21 at the rear end of the arc extinguishing chamber body 2, and the offset part 4 of the lower partition rib 32 is extended to abut between the two upper exhaust holes 21 at the rear end of the arc extinguishing chamber body 2. By reasonably optimizing the structural layout between the partition ribs and the exhaust holes, this design avoids the upper and lower partition ribs 32 blocking the upper and lower exhaust holes to ensure the smoothness of exhaust, which is beneficial to reducing the temperature rise and pressure in the arc extinguishing chamber, reducing the risk of explosion, and achieving the electrical insulation performance between adjacent exhaust channels 5, thereby improving the arc extinguishing ability and breaking capacity of the product.

[0028] As a preferred embodiment, referring to Figures 3-4 , the offset portion 4 includes a coincidence area formed by connecting between the upper partition rib 31 and the lower partition rib 32, an upper offset area 41 formed at the top of the upper partition rib 31 and located on one side of the coincidence area, and a lower offset area 42 formed at the bottom of the lower partition rib 32 and located on the other side of the coincidence area. The upper offset area 41 and the lower offset area 42 are arranged in an up-and-down offset manner. The coincidence area is formed by the cooperative contact between the top of the upper partition rib 31 and the bottom of the lower partition rib 32. The upper offset area 41 and the lower offset area 42 are stepped structures for avoiding the upper and lower exhaust holes, so that the upper exhaust hole 21 located above the lower partition rib 32 will not be blocked by the upper partition rib 31. Similarly, the lower exhaust hole 22 located below the lower partition rib 32 will not be blocked by the lower partition rib 32. The upper partition rib 31 and the lower partition rib 32 can effectively offset and avoid the upper and lower exhaust holes through the upper offset area 41 and the lower offset area 42, ensuring the smooth discharge of the arc extinguishing gas from multiple exhaust holes.

[0029] As a specific structural setting, the upper partition rib 31 and the lower partition rib 32 are bent and extend in the housing 1. The first half sections of the upper partition rib 31 and the lower partition rib 32 close to the arc extinguishing chamber body 2 are provided with the offset portion 4 and are offset and abutted up and down. The second half sections of the upper partition rib 31 and the lower partition rib 32 far from the arc extinguishing chamber body 2 coincide and abut up and down. Thus, the multiple exhaust passages formed by separating with multiple sets of partition structures 3 are also bent and extended, which is beneficial to increasing the gas flow distance, beneficial to reducing the temperature and energy of the charged gas, and reducing the probability of restriking.

[0030] In this embodiment, the housing 1 includes a housing base and a housing cover. The upper partition rib 31 and the lower partition rib 32 are respectively arranged on the housing base and the housing cover. When the housing base and the housing cover are cooperatively installed, the upper partition rib 31 and the lower partition rib 32 are driven to be connected to form the partition structure 3. Referring to Figures 1-2 , there are two sets of the partition structure 3 in the exhaust area of the housing 1. The exhaust area includes three exhaust channels 5 formed by separating with two sets of partition structures 3. Among them, an air outlet structure communicating with the three exhaust channels 5 is provided on the housing 1. The advantage of such a design is that since the partition structure 3 avoids the exhaust holes at the rear end of the arc extinguishing chamber body 2, it is beneficial for the arc extinguishing gas to be evenly discharged from the positions of the upper and lower exhaust holes at the rear end of the arc extinguishing chamber, and the arc extinguishing gas is shunted and separated through the three exhaust channels 5 for exhaust flow. In this way, the residual arc and gas can be segmented within this distance in the exhaust area, and the pressure and the energy of the charged free gas in the arc extinguishing chamber and the exhaust area can be rapidly reduced, thereby reducing the possibility of restriking of the charged gas or arc and ensuring the safety of product use.

[0031] Combined with Figures 1-3As shown in the figure, the three exhaust channels 5 are respectively the upper exhaust channel 515, the middle exhaust channel 525, and the lower exhaust channel 535 that are sequentially and spaced apart at the rear end of the arc extinguishing chamber body 2. The charged gas is divided and shunted through the upper exhaust channel 515, the middle exhaust channel 525, and the lower exhaust channel 535, thereby reducing the energy of the charged gas. In order to smoothly discharge the gas to the outside of the housing 1, a terminal groove 11 for installing a terminal is provided on the housing 1, and a partition strip is provided between the terminal groove 11 and the exhaust area. The air outlet structure includes a first air outlet hole 61 provided on the partition strip and communicating the terminal groove 11 with the upper exhaust channel 515. Further preferably, the air outlet structure further includes an air outlet buffer area 54 provided at the ends of the middle exhaust channel 525 and the lower exhaust channel 535, a second air outlet hole 62 provided at one end of the housing 1 and communicating with the air outlet buffer area 54, and a third air outlet hole 63 provided at the bottom of the housing 1 and communicating with the air outlet buffer area 54. With this structural arrangement, the gas discharged through the upper exhaust channel 515 will finally be discharged to the outside through the first air outlet hole from the terminal groove position, and the gas discharged through the middle exhaust channel 525 and the lower exhaust channel 535 will be discharged to the outside through the second air outlet hole and the third air outlet hole, reducing the pressure inside the housing 1 and avoiding the occurrence of explosion, making it safer to use. Such a design forms multiple exhaust paths on the housing 1. During normal use, external air can enter the product through multiple air outlet holes, conduct heat exchange or heat convection with the high-temperature air inside the product, thereby reducing the internal temperature of the product and having the effect of reducing temperature rise and product power consumption.

[0032] As Figure 1 shown in the figure, an arc ignition channel 7 is provided in the housing 1 and connected between the contact structure and the front end of the arc extinguishing chamber body 2. The contact structure includes a moving contact 91 and a static contact 92 that face each other. Two arc ignition members 8 are provided on both sides of the arc ignition channel 7. One of the arc ignition members 8 is connected to the static contact 92 and is used to attract the arc on the static contact 92 into the arc extinguishing chamber body 2. The other arc ignition member 8 extends and is connected between the moving contact 91 and the arc extinguishing chamber body 2 and is used to attract the arc on the head of the moving contact 91 into the arc extinguishing chamber body 2. Multiple arc-shaped arc dividing and guiding grooves are formed at intervals in the arc ignition channel 7. The arc dividing and guiding grooves play a role in dividing and guiding the arc, which can reduce the arc energy. When the moving contact 91 and the static contact 92 are disconnected to generate an arc, the arc is centrally guided into the arc extinguishing chamber body through the arc ignition channel 7 and the arc ignition members 8 to achieve arc extinguishing, accelerating the arc ignition speed and improving the arc extinguishing performance of the circuit breaker.

[0033] Obviously, the above embodiments are merely examples for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the creation of the present utility model.

Claims

1. A circuit breaker arc extinguishing exhaust system, comprising an arc extinguishing device arranged on a housing (1) and an exhaust area connected to the rear of the arc extinguishing device, wherein the arc extinguishing device comprises an arc extinguishing chamber body (2) provided with an arc extinguishing sheet group, characterized in that: The rear end of the arc extinguishing chamber body (2) is provided with a plurality of upper exhaust holes (21) and a plurality of lower exhaust holes (22) arranged in an up-and-down staggered manner. The shell (1) is provided with a plurality of baffle structures (3) for dividing the exhaust area into a plurality of exhaust channels (5). Each baffle structure (3) comprises an upper baffle rib (31) and a lower baffle rib (32) connected to each other up and down. A dislocation portion (4) that partially overlaps and extends in a dislocation manner is provided between the upper baffle rib (31) and the lower baffle rib (32), so that the dislocation portion (4) of the upper baffle rib (31) extends to abut against the rear end of the arc extinguishing chamber body (2) and is located between two of the upper exhaust holes (21), and the dislocation portion (4) of the lower baffle rib (32) extends to abut against the rear end of the arc extinguishing chamber body (2) and is located between two of the lower exhaust holes (22).

2. The circuit breaker arc extinguishing exhaust system according to claim 1, characterized in that: The offset portion (4) comprises an overlapped area formed between the upper partition rib (31) and the lower partition rib (32), an upper offset area (41) formed at the top of the upper partition rib (31) and located on one side of the overlapped area, and a lower offset area (42) formed at the bottom of the lower partition rib (32) and located on the other side of the overlapped area, wherein the upper offset area (41) and the lower offset area (42) are arranged to be offset up and down.

3. The arc extinguishing exhaust system for a circuit breaker according to claim 2, characterized in that: The upper partition ribs (31) and the lower partition ribs (32) are arranged in a bent shape and extend in the housing (1); the upper partition ribs (31) and the lower partition ribs (32) are provided with offset portions (4) at the front half close to the arc extinguishing chamber body (2) and are offset and abutted against each other up and down; the upper partition ribs (31) and the lower partition ribs (32) are overlapped and abutted against each other at the rear half away from the arc extinguishing chamber body (2).

4. A circuit breaker arc extinguishing exhaust system according to any one of claims 1 to 3, characterized in that: The shell (1) comprises a shell base and a shell cover, the upper partition ribs (31) and the lower partition ribs (32) are respectively arranged on the shell base and the shell cover, and two groups of the partition structure (3) are arranged in the exhaust area of ​​the shell (1), and the exhaust area comprises three exhaust channels (5) formed by dividing the two groups of partition structures (3).

5. The arc extinguishing exhaust system for a circuit breaker according to claim 4, characterized in that: The three exhaust channels (5) are respectively an upper exhaust channel (51) (5), a middle exhaust channel (52) (5) and a lower exhaust channel (53) (5) which are sequentially spaced and distributed at the rear end of the arc extinguishing chamber body (2); the housing (1) is provided with an outlet structure connecting the three exhaust channels (5).

6. The arc extinguishing exhaust system for a circuit breaker according to claim 5, characterized in that: The housing (1) is provided with a terminal slot (11) for mounting a wiring terminal, and an isolation strip is provided between the terminal slot (11) and the exhaust area, and the air outlet structure comprises a first air outlet hole (61) provided on the isolation strip and connecting the terminal slot (11) and the upper exhaust channel (51) (5).

7. The arc extinguishing exhaust system for a circuit breaker according to claim 6, characterized in that: The air outlet structure comprises an air outlet buffer zone (54) arranged at the ends of the middle exhaust channel (52) (5) and the lower exhaust channel (53) (5), a second air outlet hole (62) arranged at one end of the shell (1) and connected to the air outlet buffer zone (54), and a third air outlet hole (63) arranged at the bottom of the shell (1) and connected to the air outlet buffer zone (54).

8. The arc extinguishing exhaust system for a circuit breaker according to claim 1, characterized in that: The housing (1) is provided with an arc striking channel (7) connected between the contact structure and the front end of the arc extinguishing chamber body (2), two arc striking members (8) are provided on both sides of the arc striking channel (7), and a plurality of arc-shaped arc-dividing guide grooves are formed in the middle of the arc striking channel (7).

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