Arc extinguishing system and circuit breaker

Abstract

The utility model relates to the technical field of low-voltage electric appliances, in particular to an arc extinguishing system and a circuit breaker. The arc extinguishing system comprises a contact structure and an arc extinguishing chamber. The contact structure comprises a static contact and a moving contact group. The moving contact group comprises a plurality of arc contact pieces and a plurality of main contact pieces which are arranged side by side. The arc extinguish chamber and the moving contact group are arranged oppositely; the arc extinguish chamber is provided with an arc extinguish cavity, one end of the arc extinguish cavity close to the moving contact group is provided with an air inlet channel, and the opening area of the air inlet channel is reduced along the direction far away from the moving contact group; and the movable end of each arc contact piece passes through the inlet of the air inlet channel and extends into the air inlet channel. According to the arc extinguishing system provided by the invention, the structure of the arc extinguishing chamber is improved, so that the speed of the arc going deep into the arc extinguishing chamber can be improved on the basis of not increasing the volume of the arc extinguishing chamber, the breaking capacity of the arc extinguishing system is further improved, and meanwhile, the arc extinguishing system has the advantages of small volume, compact structure and the like.

Description

Technical Field

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

[0002] The arc extinguishing system is one of the key structures of an electrical switch. Usually, the arc extinguishing system includes structures such as a moving contact, a stationary contact and an arc extinguishing chamber. When the moving contact and the stationary contact are disconnected, an arc will be generated. The grid installed in the arc extinguishing chamber needs to be used to cut the generated arc to extinguish the arc.

[0003] In order to improve the arc extinguishing performance of the arc extinguishing chamber, it is generally necessary to increase the speed at which the arc enters the grid group of the arc extinguishing chamber so that the grid can effectively cut the arc and quickly extinguish the arc. To achieve this goal, the current conventional practice is to set a magnetic part on the arc extinguishing chamber to use the magnetic blowing force to accelerate the speed at which the arc enters the arc extinguishing chamber, but this structure will increase the volume of the arc extinguishing chamber, which is not conducive to the miniaturization of the circuit breaker. Utility Model Content

[0004] The first purpose of the utility model is to provide an arc extinguishing system to solve the technical problems of the existing arc extinguishing system, such as slow arc transfer, insufficient breaking capacity and large occupied space.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] An arc extinguishing system comprises a contact structure and an arc extinguishing chamber;

[0007] The contact structure comprises a stationary contact and a moving contact group, wherein the moving contact group comprises a plurality of arcing contact pieces and a plurality of main contact pieces arranged side by side, and the movable end of each of the arcing contact pieces and the movable end of each of the main contact pieces can contact or separate from the stationary contact;

[0008] The arc extinguishing chamber is arranged opposite to the moving contact group; the arc extinguishing chamber has an arc extinguishing cavity, and an air inlet channel is arranged at one end of the arc extinguishing cavity close to the moving contact group, and the opening area of ​​the air inlet channel tends to decrease in the direction away from the moving contact group;

[0009] The movable end of each arc contact piece passes through the inlet of the air inlet channel and extends into the air inlet channel.

[0010] Further, the arc extinguishing chamber comprises two arc extinguishing chamber side walls arranged opposite to each other and a grid plate group arranged between the two arc extinguishing chamber side walls, and the two arc extinguishing chamber side walls and the grid plate group are arranged to form the arc extinguishing cavity;

[0011] The air inlet channel is arranged at one end of the arc extinguishing chamber away from the grid plate group.

[0012] Furthermore, a ratio of a length of at least one of the arc contact pieces extending into the air inlet passage to an extension length of the air inlet passage is greater than or equal to 1 / 2.

[0013] Furthermore, an air outlet channel is provided at one end of the arc extinguishing chamber away from the moving contact group, and an inlet of the air outlet channel is connected to an outlet of the air inlet channel;

[0014] The opening area of ​​the air outlet channel increases in a direction away from the moving contact group.

[0015] Furthermore, each of the arc extinguishing chamber side walls includes interconnected support members and gas producing members, wherein: the two support members are respectively connected to opposite sides of the grid group; the two gas producing members are symmetrically arranged and located at one end of the grid group close to the moving contact group.

[0016] Furthermore, each of the gas producing parts is provided with a contraction surface, the contraction surface is inclined from the moving contact group to the grid group along the direction close to the arc extinguishing chamber, and the gas inlet channel is formed between the contraction surfaces on the two gas producing parts;

[0017] And / or, each of the gas producing parts is provided with an expansion surface, the expansion surface is inclined from the moving contact group to the grid group along a direction away from the arc extinguishing chamber, and the gas outlet channel is formed between the expansion surfaces on the two gas producing parts.

[0018] Furthermore, a movable end of at least one of the main contacts extends into the arc extinguishing chamber.

[0019] Furthermore, the grid plate group includes a plurality of grid plates arranged in sequence, and a limiting groove for inserting the grid plate is provided on a side of each of the gas producing parts close to the grid plate group.

[0020] Furthermore, the length of the arc contact piece is greater than the length of the main contact piece;

[0021] The movable end of the main contact piece is arranged opposite to the inlet of the air inlet passage and is outside the air inlet passage.

[0022] The second object of the utility model is to provide a circuit breaker, comprising the arc extinguishing system described in any one of the above items.

[0023] Beneficial effects of the utility model:

[0024] The utility model provides an arc extinguishing system and a circuit breaker, the arc extinguishing system includes a contact structure and an arc extinguishing chamber; the contact structure includes a static contact and a moving contact group, the moving contact group includes a plurality of arc contact pieces and a plurality of main contact pieces arranged side by side, the movable end of each arc contact piece and the movable end of each main contact piece can contact or separate with the static contact; the arc extinguishing chamber is arranged opposite to the moving contact group; the arc extinguishing chamber has an arc extinguishing cavity, an air inlet channel is arranged at one end of the arc extinguishing cavity close to the moving contact group, and the opening area of ​​the air inlet channel tends to decrease in the direction away from the moving contact group; the movable end of each arc contact piece passes through the entrance of the air inlet channel and extends into the air inlet channel. The arc extinguishing system provided by the present application can improve the speed of the arc penetrating into the arc extinguishing chamber without increasing the volume of the arc extinguishing chamber by improving the structure of the arc extinguishing cavity, thereby improving the breaking capacity of the arc extinguishing system, and at the same time, the arc extinguishing system has the advantages of small size and compact structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of the top view of the arc extinguishing system provided in an embodiment of the utility model;

[0027] Figure 2 A schematic diagram of the connection structure of the contact structure, grid plate group and gas generating member provided in the embodiment of the utility model;

[0028] Figure 3 A schematic diagram of the top view of the arc extinguishing chamber provided in an embodiment of the utility model;

[0029] Figure 4 A schematic diagram of the top view of the two gas producing components provided in the embodiment of the utility model;

[0030] Figure 5 A schematic diagram of the three-dimensional structure of two gas producing parts provided in one embodiment of the utility model;

[0031] Figure 6 A schematic diagram of the connection structure between the grid plate group and the gas producing member provided in the embodiment of the utility model;

[0032] Figure 7 A schematic diagram of the three-dimensional structure of two gas producing components provided in another embodiment of the utility model;

[0033] Figure 8A schematic diagram of the connection structure of a gas-generating component and a magnetic component provided in another embodiment of the utility model.

[0034] icon:

[0035] 1-contact structure; 11-stationary contact; 111-first stationary contact; 112-second stationary contact; 12-moving contact group; 121-arc contact piece; 122-main contact piece;

[0036] 2-arc extinguishing chamber; 21-arc extinguishing chamber; 211-air inlet channel; 212-air outlet channel; 22-arc extinguishing chamber side wall; 221-support member; 222-gas producing member; 2221-contraction surface; 2222-expansion surface; 2223-first clamping block; 2224-limiting groove; 2225-installation cavity; 23-grid group; 24-movable arc-starting plate; 241-fixing part; 242-guiding part; 25-magnetic member. DETAILED DESCRIPTION

[0037] The technical solution of the utility model will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0038] It should be noted that in the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0039] It should be noted that in the description of the present invention, the terms "connection" and "installation" 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 directly connected or connected through an intermediate medium; it can be a mechanical connection or an electrical connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] In conventional arc extinguishing systems, the speed at which the arc enters the grid group of the arc extinguishing chamber is slow, and the breaking capacity of the arc extinguishing system is low. For arc extinguishing systems with magnetic parts on the arc extinguishing chamber, brackets for fixing the magnetic parts are usually required, resulting in a more complicated structure of the arc extinguishing system; in addition, the setting of the magnetic parts increases the volume of the arc extinguishing chamber, which is not conducive to the miniaturization of the circuit breaker.

[0041] Based on this, an embodiment of the present invention provides an arc extinguishing system, referring to Figure 1 and Figure 2 , the arc extinguishing system comprises a contact structure 1 and an arc extinguishing chamber 2;

[0042] The contact structure 1 includes a stationary contact 11 and a moving contact group 12. The moving contact group 12 includes a plurality of arcing contact pieces 121 and a plurality of main contact pieces 122 arranged side by side. The movable end of each arcing contact piece 121 and the movable end of each main contact piece 122 can contact or separate from the stationary contact 11.

[0043] The arc extinguishing chamber 2 is arranged opposite to the moving contact group 12; the arc extinguishing chamber 2 has an arc extinguishing cavity 21, and an air inlet channel 211 is provided at one end of the arc extinguishing cavity 21 close to the moving contact group 12, and the opening area of ​​the air inlet channel 211 tends to decrease in the direction away from the moving contact group 12;

[0044] The movable end of each arc contact piece 121 passes through the entrance of the air inlet channel 211 and extends into the air inlet channel 211 .

[0045] In the above structure, the main contact 122 is mainly used for conducting and cutting off the current, and the arc contact 121 is mainly used for striking the arc; when the current is disconnected, the main contact 122 is disconnected from the static contact 11 before the arc contact 121, and the generated arc is guided by the arc contact 121 into the air inlet channel 211. The opening area of ​​the air inlet channel 211 tends to decrease in the direction away from the moving contact group 12, that is, the air inlet channel 211 has a contraction structure along the air flow direction; the contraction structure of the air inlet channel 211 can increase the pressure difference between the front and rear ends of the arc extinguishing chamber 2, thereby accelerating the air flow from the front end of the arc extinguishing chamber 2 to the back of the arc extinguishing chamber 2. Under the impetus of the air flow, the arc guided into the air inlet channel 211 by the arc contact 121 and the arc that may appear at the main contact 122 can be accelerated and blown into the arc extinguishing chamber 2, thereby effectively improving the breaking capacity of the arc extinguishing system. In addition, since the entrance area of ​​the air inlet channel 211 is large, it is conducive to the arc that may appear at the position of each main contact piece 122 to enter the air inlet channel 211, so as to avoid the problem of the arc that may appear at the main contact piece 122 not being extinguished in time and causing the breaking failure.

[0046] The arc extinguishing system provided in the present application improves the structure of the arc extinguishing chamber 21, and can increase the speed at which the arc penetrates into the arc extinguishing chamber 2 without increasing the volume of the arc extinguishing chamber 2, thereby improving the breaking capacity of the arc extinguishing system, while enabling the arc extinguishing system to have the advantages of small size and compact structure.

[0047] Optionally, the number of the arc contact piece 121 and the number of the main contact piece 122 can be one or more. Figure 1 When there are multiple arcing contact pieces 121, the multiple arcing contact pieces 121 are arranged side by side to form an arcing contact piece group, and one or more main contact pieces 122 are arranged on at least one side of the arcing contact piece group along the width direction. Figure 1 In the illustrated embodiment, a plurality of main contact pieces 122 are respectively disposed on both sides of the arc contact piece group along the width direction.

[0048] In the above structure, the multiple arc contact pieces 121 and the multiple main contact pieces 122 can divide the current passing through the contact structure 1 into several currents in the same direction, thereby effectively improving the short-time withstand capability.

[0049] Furthermore, the length of the arc contact piece 121 is greater than the length of the main contact piece 122;

[0050] The movable end of the main contact piece 122 is disposed opposite to the entrance of the air inlet passage 211 and is outside the air inlet passage 211 .

[0051] Since the main contact 122 is mainly used for conducting and cutting off the current, the main contact 122 needs to maintain a good heat dissipation effect as much as possible during the process of conducting the current. In this embodiment, the arc contact 121 responsible for arc initiation extends into the air inlet channel 211 to ensure that the arc can be concentrated and guided into the air inlet channel 211 to prevent the arc from spreading; while the main contact 122 responsible for conducting and cutting off the current does not extend into the air inlet channel 211, on the one hand to avoid increasing the volume of the arc extinguishing chamber 2, on the other hand to ensure that the main contact 122 can dissipate heat in time during the process of current connection; the active end of the main contact 122 is arranged relative to the entrance of the air inlet channel 211 to ensure that the arc that may appear at the active end of the main contact 122 can smoothly enter the air inlet channel 211 with the air flow.

[0052] It is understandable that in other embodiments, if the heat dissipation effect of the main contact piece 122 and the volume of the arc extinguishing chamber 2 are not considered, the movable end of at least one main contact piece 122 can also extend into the arc extinguishing chamber 21 (specifically, the air inlet channel 211).

[0053] Continue to refer to Figure 1 On the basis of the above structure, the ratio of the length of at least one arc contact piece 121 extending into the air inlet channel 211 to the extension length H of the air inlet channel 211 is greater than or equal to 1 / 2. The above arrangement can ensure that the arc at the arc contact piece 121 is located in the air inlet channel 211 after arcing, further preventing arc spillage.

[0054] Reference Figure 2 The static contact 11 has a first static contact 111 for contacting the arc contact piece 121 and a second static contact 112 for contacting the main contact piece 122; the first static contact 111 is located in the air inlet channel 211, and the second static contact 112 is located at the entrance of the air inlet channel 211.

[0055] Reference Figure 3 The arc extinguishing chamber 2 includes two arc extinguishing chamber side walls 22 arranged opposite to each other and a grid plate group 23 arranged between the two arc extinguishing chamber side walls 22. The two arc extinguishing chamber side walls 22 and the grid plate group 23 are arranged to form an arc extinguishing cavity 21;

[0056] The air inlet channel 211 is disposed at one end of the arc extinguishing chamber 21 away from the grid assembly 23 .

[0057] Analyzing the above structure, the air inlet channel 211 extends from the moving contact group 12 to the grid group 23, and the opening area of ​​the air inlet channel 211 decreases from the moving contact group 12 to the grid group 23. Driven by the pressure difference at both ends of the air inlet channel 211, the arc at the moving contact group 12 can be accelerated to enter the grid group 23.

[0058] Reference Figure 2 and Figure 3 The arc extinguishing chamber 2 also includes a movable arc-striking plate 24, which includes a fixed portion 241 and a guide portion 242 connected to each other, wherein: the fixed portion 241 is located above the grid group 23, and the guide portion 242 is arranged between the two arc extinguishing chamber side walls 22. The guide portion 242 is a V-shaped structure, including a first guide plate and a second guide plate, wherein: the first guide plate is inclined downward from the fixed portion 241 to the active end of the arc contact piece 121 in the current disconnected state; the second guide plate is inclined upward from the first guide plate to the top of the active end of the arc contact piece 121 in the current disconnected state. The movable arc-striking plate 24 is used to guide the arc root at the arc contact piece 121 into the grid group 23 to prevent the arc from spreading from the top of the arc extinguishing chamber 2.

[0059] Continue to refer to Figure 3 An outlet channel 212 is provided at one end of the arc extinguishing chamber 21 away from the moving contact group 12, and the inlet of the outlet channel 212 is connected to the outlet of the inlet channel 211;

[0060] The opening area of ​​the air outlet channel 212 increases in a direction away from the moving contact group 12 .

[0061] In the above structure, the outlet channel 212 is an expansion structure along the air flow direction, and the inlet channel 211 and the outlet channel 212 form a Laval air channel. Referring to the principle of the Laval air channel, the air flow flowing out of the inlet channel 211 can be further accelerated and diffused through the outlet channel 212, thereby further increasing the speed at which the arc enters the grid group 23.

[0062] In this embodiment, the air inlet channel 211 is trumpet-shaped, and the opening area of ​​the air inlet channel 211 gradually decreases from the inlet of the air inlet channel 211 to the outlet of the air inlet channel 211;

[0063] And / or, the air outlet channel 212 is trumpet-shaped, and the opening area of ​​the air outlet channel 212 gradually increases from the inlet of the air outlet channel 212 to the outlet of the air outlet channel 212 .

[0064] Furthermore, each arc extinguishing chamber side wall 22 includes interconnected support members 221 and gas producing members 222, wherein: the two support members 221 are respectively connected to opposite sides of the grid group 23; the two gas producing members 222 are symmetrically arranged and located at one end of the grid group 23 close to the moving contact group 12.

[0065] Reference Figure 4 Each gas producing member 222 is provided with a contraction surface 2221, the contraction surface 2221 is inclined from the moving contact group 12 to the grid group 23 along the direction close to the arc extinguishing chamber 21, and an air inlet channel 211 is formed between the contraction surfaces 2221 on the two gas producing members 222;

[0066] And / or, each gas producing member 222 is provided with an expansion surface 2222 , the expansion surface 2222 is inclined from the moving contact group 12 to the grid group 23 along the direction away from the arc extinguishing chamber 21 , and a gas outlet channel 212 is formed between the expansion surfaces 2222 on the two gas producing members 222 .

[0067] In this embodiment, the outer contour of the cross section of each gas producing part 222 is triangular or trapezoidal, and the two sides of the triangle or the two sides of the trapezoid correspond to the contraction surface 2221 and the expansion surface 2222 respectively; the other side of the triangle or the long side of the trapezoid is away from the arc extinguishing chamber 21; there is a smooth transition between the contraction surface 2221 and the expansion surface 2222 close to the arc extinguishing chamber 21.

[0068] Through the above structure, when the arc extinguishing chamber 2 is installed, an air inlet channel 211 and an air outlet channel 212 are naturally formed between the two gas producing parts 222 .

[0069] Furthermore, the support member 221 is used to support and connect the gas producing member 222 and the grid plate group 23. The support member 221, the gas producing member 222 and the grid plate group 23 can be connected to each other by means of snap connection or screw connection. The following is a connection method provided by an embodiment of the utility model.

[0070] Reference Figure 5 In each arc extinguishing chamber side wall 22, a plurality of first card blocks 2223 are provided on the gas generating member 222, a plurality of first card slots are provided on the supporting member 221, a plurality of first card blocks 2223 and a plurality of first card slots correspond one to one, and the first card blocks 2223 are clamped in the corresponding first card slots;

[0071] Alternatively, in each arc extinguishing chamber side wall 22, a plurality of second card slots are provided on the gas producing part 222, a plurality of second card blocks are provided on the supporting part 221, the plurality of second card slots correspond to the plurality of second card blocks one by one, and the second card blocks are arranged in the corresponding second card slots.

[0072] Figure 5 In the illustrated embodiment, four first clamping blocks 2223 are provided on the gas-producing part 222, and correspondingly, four first clamping grooves are provided on the support part 221. The first clamping blocks 2223 and the first clamping grooves are engaged with each other to limit the displacement of the gas-producing part 222 relative to the support part 221 in the front-to-back and up-and-down directions.

[0073] Reference Figure 5 and Figure 6 The grid plate group 23 includes a plurality of grid plates arranged in sequence, and a limiting groove 2224 for inserting a grid plate is provided on a side of each gas producing member 222 close to the grid plate group 23. Under the common limiting of the grid plate group 23 and the support member 221, the two gas producing members 222 can be limited to approach or move away from each other.

[0074] Through the above arrangement, the two gas generating members 222 and the grid plate group 23 can be fixed between the two supporting members 221 .

[0075] Reference Figure 7 and Figure 8 As an optional embodiment, each gas generating member 222 is provided with a mounting cavity 2225, and a magnetic member 25 is provided in the mounting cavity 2225. When the current is disconnected, the magnetic blowing force generated by the magnetic member 25 can further accelerate the speed at which the arc penetrates into the arc extinguishing chamber 2, thereby further improving the breaking capacity of the arc extinguishing system.

[0076] Since the magnetic component 25 is arranged inside the gas-producing component 222, there is no need to set up a bracket for fixing the magnetic component 25, so that the internal space of the gas-producing component 222 can be fully utilized, and the breaking capacity of the arc extinguishing system can be further improved without increasing the volume of the arc extinguishing chamber 2; the magnetic component 25 is enclosed in the gas-producing component 222, which can effectively isolate the magnetic component 25 and prevent the magnetic component 25 from interfering with other electronic structures, while fixing and protecting the magnetic component 25.

[0077] Based on the above structure, the magnetic member 25 is in the shape of a long strip and is arranged vertically. Two magnetic members 25 are arranged opposite to each other, and a magnetic blowing space is formed between the two magnetic members 25; when the arc passes through the magnetic blowing space, it can be accelerated to move toward the grid group 23 under the magnetic blowing force.

[0078] In summary, in the arc extinguishing system provided by the present application, by arranging an air inlet channel 211 whose opening gradually shrinks along the air flow direction and an air outlet channel 212 whose opening gradually expands along the air flow direction in the arc extinguishing chamber 21, the arc can be accelerated to move from the moving contact group 12 to the grid group 23; the length of the arc contact piece 121 is greater than the length of the main contact piece 122, and the movable end of the arc contact piece 121 extends into the air inlet channel 211, ensuring that the arc can enter the arc extinguishing chamber 2 to avoid arc spillage; the main contact piece 122 is located outside the air inlet channel 211 and is arranged opposite to the entrance of the air inlet channel 211, which is conducive to the arc that may appear at the main contact piece 122 to enter the air inlet channel 211; a magnetic part 25 is installed in the gas producing part 222, which can further accelerate the movement of the arc without increasing the volume of the arc extinguishing chamber 2.

[0079] Due to the adoption of the above structure, the arc extinguishing system provided by the present application has the advantages of high breaking capacity, small size, compact and reliable structure, high short-time tolerance and arc not easy to spread, and has high practicality.

[0080] Another embodiment of the present invention provides a circuit breaker, which includes the arc extinguishing system described in any of the above embodiments. The circuit breaker at least has the technical effects of the above arc extinguishing system, which will not be described in detail here.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. An arc extinguishing system, characterized in that: It comprises a contact structure (1) and an arc extinguishing chamber (2); The contact structure (1) comprises a stationary contact (11) and a moving contact group (12); the moving contact group (12) comprises a plurality of arcing contact pieces (121) and a plurality of main contact pieces (122) arranged side by side; the movable end of each arcing contact piece (121) and the movable end of each main contact piece (122) are both capable of contacting or separating from the stationary contact (11); The arc extinguishing chamber (2) is arranged opposite to the moving contact group (12); the arc extinguishing chamber (2) comprises an arc extinguishing cavity (21); an air inlet channel (211) is arranged at one end of the arc extinguishing cavity (21) close to the moving contact group (12); and an opening area of ​​the air inlet channel (211) tends to decrease in a direction away from the moving contact group (12); The movable end of each arc contact piece (121) passes through the entrance of the air inlet channel (211) and extends into the air inlet channel (211).

2. The arc extinguishing system according to claim 1, characterized in that: The arc extinguishing chamber (2) comprises two arc extinguishing chamber side walls (22) arranged opposite to each other and a grid plate group (23) arranged between the two arc extinguishing chamber side walls (22); the two arc extinguishing chamber side walls (22) and the grid plate group (23) enclose the arc extinguishing cavity (21); The air inlet channel (211) is arranged at an end of the arc extinguishing chamber (21) away from the grid plate group (23).

3. The arc extinguishing system according to claim 1, characterized in that: The ratio of the length of at least one of the arc contact pieces (121) extending into the air inlet channel (211) to the extension length of the air inlet channel (211) is greater than or equal to 1 / 2.

4. The arc extinguishing system according to claim 2, characterized in that: An outlet channel (212) is provided at one end of the arc extinguishing chamber (21) away from the moving contact group (12), and an inlet of the outlet channel (212) is connected to an outlet of the inlet channel (211); The opening area of ​​the air outlet channel (212) tends to increase in a direction away from the moving contact group (12).

5. The arc extinguishing system according to claim 4, characterized in that: Each arc extinguishing chamber side wall (22) comprises a supporting member (221) and a gas producing member (222) which are connected to each other, wherein: the two supporting members (221) are respectively connected to opposite sides of the grid plate group (23); and the two gas producing members (222) are symmetrically arranged and located at one end of the grid plate group (23) close to the moving contact group (12).

6. The arc extinguishing system according to claim 5, characterized in that: Each of the gas producing parts (222) is provided with a contraction surface (2221), the contraction surface (2221) is inclined from the moving contact group (12) to the grid group (23) along a direction close to the arc extinguishing chamber (21), and the gas inlet channel (211) is formed between the contraction surfaces (2221) on the two gas producing parts (222); And / or, each of the gas producing parts (222) is provided with an expansion surface (2222), and the expansion surface (2222) is inclined from the moving contact group (12) to the grid group (23) in a direction away from the arc extinguishing chamber (21), and the gas outlet channel (212) is formed between the expansion surfaces (2222) on the two gas producing parts (222).

7. The arc extinguishing system according to claim 1, characterized in that: The movable end of at least one of the main contacts (122) extends into the arc extinguishing chamber (21).

8. The arc extinguishing system according to claim 5, characterized in that: The grid plate group (23) comprises a plurality of grid plates arranged in sequence, and a limiting groove (2224) for inserting the grid plate is provided on a side of each gas producing component (222) close to the grid plate group (23).

9. The arc extinguishing system according to claim 1, characterized in that: The length of the arc contact piece (121) is greater than the length of the main contact piece (122); The movable end of the main contact piece (122) is arranged opposite to the inlet of the air inlet channel (211) and is outside the air inlet channel (211).

10. A circuit breaker, characterized in that: The invention comprises an arc extinguishing system as claimed in any one of claims 1 to 9.

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