Circuit breaker

Abstract

The utility model relates to the technical field of low-voltage electric appliances, and discloses a circuit breaker. The circuit breaker comprises a base, an arc extinguishing mechanism and a contact mechanism, wherein the arc extinguishing mechanism and the contact mechanism are mounted in the base; a limiting wall is arranged in the base, the limiting wall is used for defining a mounting position of the arc extinguishing mechanism, and a first opening is formed in the limiting wall; an arc extinguishing chamber is formed in the arc extinguishing mechanism, and an inlet of the arc extinguishing chamber is communicated with the first opening; the contact mechanism comprises a movable contact piece and a reverse spraying prevention piece, the movable contact piece is rotatably connected with the base, and one end of the movable contact piece penetrates through the first opening and the inlet of the arc extinguish chamber to be located in the arc extinguish chamber; and the reverse spraying prevention piece is located on the side, away from the arc extinguishing mechanism, of the limiting wall and connected with the movable contact piece, and the reverse spraying prevention piece is configured to be matched with the movable contact piece to shield at least one part of the first opening. The circuit breaker disclosed by the utility model can prevent electric arc from flowing out reversely, and improves the switching performance and the service life of a product.

Description

[0001] This application claims priority to Chinese patent application No. 202420854411.6, filed on April 23, 2024, with invention name “Circuit Breaker”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of low-voltage electrical appliances, and in particular to a circuit breaker. Background Art

[0003] There is an electromotive repulsive force between the moving contact and the stationary contact of the circuit breaker, and the magnitude of the repulsive force is proportional to the magnitude of the current passing through the contact. When a short-circuit current passes through the contact, the electromotive repulsive force generated can cause the moving contact to be repelled in advance and disconnected from the stationary contact before the switch mechanism operates, thereby generating an arc.

[0004] However, after the switch mechanism is actuated and released, a gap is formed between the lower end of the rotating shaft of the moving contact and the housing. Due to the flow of gas, the arc may not flow completely to the arc extinguishing grid, but flow out in the opposite direction from the gap at the lower end of the rotating shaft. As a result, the high-temperature free gas flows to the metal support of the moving contact, which can easily cause the metal support to burn, resulting in reduced switching performance and service life of the equipment. Utility Model Content

[0005] In view of this, the present application provides a circuit breaker that can prevent the arc from flowing in the opposite direction, thereby improving the switching performance and service life of the product.

[0006] This application specifically adopts the following technical solutions:

[0007] The present application provides a circuit breaker, the circuit breaker comprising a base, and an arc extinguishing mechanism and a contact mechanism installed inside the base;

[0008] The base has a limiting wall inside, the limiting wall is used to enclose the installation position of the arc extinguishing mechanism, and the limiting wall is provided with a first opening;

[0009] An arc extinguishing chamber is formed in the arc extinguishing mechanism, and an entrance of the arc extinguishing chamber is communicated with the first opening;

[0010] The contact mechanism includes a moving contact and an anti-backspray component, the moving contact is rotatably connected to the base, and one end of the moving contact passes through the first opening and the entrance of the arc extinguishing chamber and is located in the arc extinguishing chamber; the anti-backspray component is located on the side of the limiting wall away from the arc extinguishing mechanism and is connected to the moving contact, and the anti-backspray component is configured to cooperate with the moving contact to block at least a portion of the first opening.

[0011] Optionally, the surface of the limiting wall away from the arc extinguishing mechanism has a first curved surface, and the surface of the back-spray prevention component facing the limiting wall has a second curved surface;

[0012] The circle where the first arc surface is located and the circle where the second arc surface is located are concentric circles, and the centers of the concentric circles are located on the rotation axis of the movable contact member.

[0013] Optionally, the base includes a first seat portion and a second seat portion that are detachably connected;

[0014] The first seat portion has a first wall, the first wall is provided with a first groove, and the opening of the first groove faces the second seat portion;

[0015] The second seat portion has a second wall body, the second wall body and the first wall body constitute the limiting wall, the first arc surface is located on the second wall body, a second groove is provided on the second wall body, and the second groove is connected with the first groove to form the first opening.

[0016] Optionally, the contact mechanism further comprises a static contact, and the static contact and the dynamic contact can be in contact and cooperate with each other in the arc extinguishing chamber;

[0017] When the moving contact is in the extreme position, the side of the moving contact facing away from the static contact is in contact with the bottom of the first groove, and the lower end of the anti-backspray component is located at the lower side of the bottom of the second groove, wherein the extreme position is the position where the moving contact reaches the maximum rotation angle relative to the static contact.

[0018] Optionally, a tangent direction of a side of the first curved surface close to the first seat portion is parallel to a length direction of the first opening; and / or, the length direction of the first opening is parallel to a height direction of the base.

[0019] Optionally, the back-spray prevention component is located on the lower side of the moving contact, and the orthographic projection of the lower end of the back-spray prevention component on the opening plane of the first opening is located on the lower side of the first opening, wherein the lower side of the moving contact is the side of the moving contact close to the static contact in the contact mechanism.

[0020] Optionally, the width of the back-spray prevention member is greater than or equal to the width of the first opening, and the width direction of the first opening is parallel to the rotation axis of the movable contact member.

[0021] Optionally, the moving contact comprises a rotating part and a contact part;

[0022] The rotating part is located at a side of the back-spray prevention component away from the limiting wall and is connected to the back-spray prevention component. The rotating part is rotatably matched with the base, and a second opening is formed on the rotating part.

[0023] One end of the contact portion extends into the interior of the rotating portion through the second opening and is connected to the rotating portion, and the other end of the contact portion is located in the arc extinguishing chamber.

[0024] Optionally, the rotating portion and the back-spray prevention component are an integrally formed structure.

[0025] Optionally, the moving contact further comprises an insulating protection portion, and the insulating protection portion is located on a side of the moving contact and the anti-back-spraying member close to the static contact in the contact mechanism, wherein:

[0026] The insulating protection portion wraps at least a portion of the surface of the contact portion facing the static contact; and / or,

[0027] The insulating protective portion wraps at least a portion of the surface of the backsplash prevention component facing the first opening.

[0028] In the circuit breaker provided by the embodiment of the present application, the arc extinguishing mechanism and the contact mechanism are both installed inside the base, an arc extinguishing chamber is formed in the arc extinguishing mechanism, a first opening is formed on the limiting wall of the base, and the first opening is connected to the entrance of the arc extinguishing chamber; the contact mechanism includes a moving contact and an anti-back-spraying member, one end of the moving contact extends into the arc extinguishing chamber and contacts and cooperates with the static contact therein, the other end of the moving contact is rotatably connected to the base, and the anti-back-spraying member is located on the side of the limiting wall away from the arc extinguishing mechanism, and is connected to the moving contact, so that it can rotate synchronously under the drive of the moving contact. Therefore, after the moving contact and the static contact are disconnected and an arc is generated, the moving contact and the anti-back-spraying member cooperate to block at least a portion of the first opening, thereby preventing the arc from flowing out in reverse and burning the contact support in the contact mechanism, thereby ensuring that the switching performance of the circuit breaker is not affected by arc burning and improving its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 is a structural schematic diagram of a circuit breaker provided in an embodiment of the present application;

[0031] Figure 2 yes Figure 1 An exploded view of the circuit breaker shown;

[0032] Figure 3 is along Figure 1 Schematic diagram of the cross-section structure after cutting along the AA line;

[0033] Figure 4 is along Figure 1 Schematic diagram of the cross-section structure after cutting along the middle BB line;

[0034] Figure 5 It is a partial structural schematic diagram of a contact mechanism provided in an embodiment of the present application;

[0035] Figure 6 is along Figure 1 Front view of the cross-section structure after cutting along the AA line;

[0036] Figure 7 The base provided in the embodiment of the present application is along Figure 1 Schematic diagram of the structure after sectioning along the midline BB;

[0037] Figure 8 is along Figure 1 Schematic diagram of the cross-section structure after cutting along the CC line;

[0038] Fig. 9 It is a schematic diagram of an assembly structure of a moving contact member and a back-spray prevention member provided in an embodiment of the present application;

[0039] Fig.10 It is a schematic diagram of the integrally formed structure of the rotating part and the anti-backspray component provided in an embodiment of the present application.

[0040] Reference numerals:

[0041] 100. Circuit breaker;

[0042] 1. base; 11. limiting wall; 111. first arc surface; 12. first opening; 13. first seat; 131. first wall; 132. first groove; 133. first groove bottom; 14. second seat; 141. second wall; 142. second groove; 143. second groove bottom;

[0043] 2. Arc extinguishing mechanism; 21. Arc extinguishing chamber; 211. Entrance;

[0044] 3. Contact mechanism; 31. Moving contact; 311. Rotating part; 3111. Second opening; 312. Contact part; 313. Insulating protection part; 32. Back-spray prevention part; 321. Second arc surface; 33. Static contact;

[0045] 4. Switch mechanism. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0048] The present application embodiment provides a circuit breaker 100, whose overall appearance is as follows Figure 1 shown. Figure 2 FIG. 1 is an exploded view of the circuit breaker 100, showing its internal structure. Figure 2 As shown, the circuit breaker 100 includes a base 1 , and an arc extinguishing mechanism 2 and a contact mechanism 3 installed inside the base 1 .

[0049] The base 1 has a first mounting position for mounting the arc extinguishing mechanism 2 and a second mounting position for mounting the contact mechanism 3. In some examples, the number of the first mounting position and the number of the second mounting position are both two, corresponding to the L pole and the N pole, respectively. Figure 2 A limiting wall 11 is provided inside the base 1 , and the limiting wall 11 is used to enclose a first installation position, and a first opening 12 is also provided on the limiting wall 11 .

[0050] like Figure 3 As shown, an arc extinguishing chamber 21 is provided in the arc extinguishing mechanism 2, and the arc extinguishing chamber 21 is a place where the moving contact and the static contact in the contact mechanism 3 are in contact and matched, and is also a place where the power arc moves and extinguishes after the moving contact and the static contact are disconnected to generate an arc. In some examples. The arc extinguishing mechanism 2 includes two insulating gas-producing parts (not shown in the figure) arranged opposite to each other, and the two insulating gas-producing parts can be independent of each other or connected to each other; there is a gap between the two insulating gas-producing parts, which is used to constitute at least a part of the arc extinguishing chamber 21, and the inlet 211 of the arc extinguishing chamber 21 is formed on one side of the two insulating gas-producing parts, and the outlet of the arc extinguishing chamber 21 (not shown in the figure) is formed on the other side of the two insulating gas-producing parts, and the inlet 211 is opposite to the outlet, and a plurality of arc extinguishing grids for extinguishing and cooling the arc are also provided at the outlet. Among them, the inlet 211 of the arc extinguishing chamber 21 corresponds to and is connected to the first opening 12. For example, the opening direction of the inlet 211 of the arc extinguishing chamber 21 is the same as the opening direction of the first opening 12.

[0051] Continue to see Figure 3The contact mechanism 3 includes a static contact 33, a dynamic contact 31 and an anti-back-spraying member 32. The static contact 33 is fixed on the base 1, and at least a part of the static contact 33 is located in the arc extinguishing chamber 21; one end of the dynamic contact 31 is rotatably connected to the base 1, and the other end of the dynamic contact 31 passes through the first opening 12 and the entrance 211 of the arc extinguishing chamber 21 in sequence and extends into the arc extinguishing chamber 21, so that as the dynamic contact 31 rotates, it can approach or move away from the static contact 33, thereby realizing the conduction and disconnection of the static contact 33 and the dynamic contact 31, and then realizing the conduction and disconnection of the circuit breaker 100; the anti-back-spraying member 32 is located on the side of the limiting wall 11 away from the arc extinguishing mechanism 2, and is connected to the dynamic contact 31, so that it can rotate synchronously with the dynamic contact 31, and the anti-back-spraying member 32 is configured to cooperate with the dynamic contact 31 to cover at least a part of the first opening 12.

[0052] Alternatively, if Figure 1 As shown, the base 1 may further include a switch mechanism 4 mounted on the base 1 , and the switch mechanism 4 is used to actuate under external actuation to drive the moving contact 31 in the contact mechanism 3 to actuate so as to disconnect or connect the moving contact 31 with the static contact 33 .

[0053] Therefore, in the circuit breaker 100 provided in the embodiment of the present application, when the arc generated when the moving contact 31 and the static contact 33 are disconnected flows back toward the inlet 211 of the arc extinguishing chamber 21 and the first opening 12, the moving contact 31 and the anti-backspray component 32 can block the arc on one side of the first opening 12, thereby preventing the arc from flowing to the metal support in the contact system, thereby preventing the metal support from burning, improving the switching performance of the circuit breaker 100 product, and increasing the service life of the product.

[0054] In some embodiments of the present application, Figure 4 As shown, the surface of the limiting wall 11 away from the arc extinguishing mechanism 2 has a first arc surface 111; Figure 5 As shown, the surface of the back-spray prevention member 32 facing the limiting wall 11 has a second arc surface 321. The first arc surface 111 and the second arc surface 321 are adapted in shape. For example, the arc extinguishing system is located on the convex side of the first arc surface 111 and on the convex side of the second arc surface 321.

[0055] like Figure 6 As shown, the circle where the first arc surface 111 is located and the circle where the second arc surface 321 is located are concentric circles, wherein the radius of the circle where the first arc surface 111 is located is smaller than the radius of the circle where the second arc surface 321 is located; the center of the concentric circle is located on the rotation axis of the moving contact 31, so that when the moving contact 31 drives the anti-backspray component 32 to rotate, the second arc surface 321 is always in close proximity to the first arc surface 111, thereby preventing high-temperature free gas from being ejected in the opposite direction from the first opening 12 when an electric arc is generated, and escaping from between the first arc surface 111 and the second arc surface 321.

[0056] In some embodiments of the present application, see Figure 6 The tangent direction of the first arc surface 111 close to the first seat portion 13 is parallel to the length direction of the first opening 12, wherein the tangent direction is Figure 6 Correspondingly, the surface of the first wall 131 on the first seat 13 away from the arc extinguishing mechanism 2 is a plane.

[0057] By adopting the above arrangement, the difficulty of matching the first wall 131 in the first seat 13 with the second wall 141 in the second seat 14 is reduced, thereby reducing the difficulty of processing.

[0058] Optionally, the length direction of the first opening 12 is parallel to the height direction of the base 1 .

[0059] Optionally, when the movable contact member 31 rotates to the limit position, the position of the upper end of the back-spray prevention member 32 corresponds to the position of the first curved surface 111 close to the first seat portion 13 .

[0060] In some embodiments of the present application, Figure 7 As shown, the base 1 includes a first seat portion 13 and a second seat portion 14, and the first seat portion 13 and the second seat portion 14 are detachably connected. Exemplarily, the first seat portion 13 and the second seat portion 14 can be connected by screws (not shown in the figure), or can be connected by a snap connection.

[0061] Continue to see Figure 7 A first wall 131 is vertically disposed inside the first seat 13, and a first groove 132 is disposed on the first wall 131, and the first groove 132 opens toward the second seat 14; a second wall 141 is vertically disposed inside the second seat 14, and a second groove 142 is disposed on the second wall 141, and the second groove 142 opens toward the first seat 13. Therefore, after the first seat and the second seat are assembled, the first wall 131 and the second wall 141 cooperate to form the limiting wall 11, and the first groove 132 and the second groove 142 are correspondingly connected to form the first opening 12.

[0062] Optionally, the movable contact member 31 is rotatably connected to the second seat portion 14 , and accordingly, the first curved surface 111 is located on the second wall 141 for matching with the second curved surface 321 on the backspray prevention member 32 .

[0063] By manufacturing the base 1 into a first seat portion 13 and a second seat portion 14 that are detachably connected, the assembly of the arc extinguishing mechanism 2, the contact mechanism 3, etc. can be facilitated, thereby improving the assembly efficiency of the product.

[0064] In some embodiments of the present application, Figure 6As shown, the back-spray prevention member 32 is located at the lower side of the moving contact member 31, and the orthographic projection of the lower end of the back-spray prevention member 32 on the opening plane of the first opening 12 is located at the lower side of the first opening 12. The lower side of the moving contact member 31 is the side of the moving contact member 31 close to the static contact member 33, the lower end of the back-spray prevention member 32 is the end of the back-spray prevention member 32 away from the moving contact member 31, and the lower side of the first opening 12 is the side of the first opening 12 away from the first seat 13.

[0065] The lower end of the back-spray prevention member 32 is located at the lower side of the first opening 12, which means that the height of the back-spray prevention member 32 is lower than or equal to the height of the lower end of the first opening 12. Figure 6 In the figure, the height of the lower end of the backspray prevention member 32 is marked as H1, and the height of the lower end of the first opening 12 is marked as H2, H1≤H2, so the height of the lower end of the backspray prevention member 32 is flush with or lower than the height of the lower end of the first opening 12. The height direction refers to the height direction of the base 1, and the height of a specific position refers to the distance between the position and the bottom wall of the base 1.

[0066] Specifically, during the rotation process after the moving contact 31 and the stationary contact 33 are separated, and when the moving contact 31 is at the limit position, the lower end of the back-spray prevention member 32 is always located at the lower side of the first opening 12, so that the back-spray prevention member 32 can always cover the portion of the first opening 12 below the moving contact 31, and prevent the high-temperature free gas from being reversely sprayed through the first opening 12. The limit position refers to the position where the moving contact 31 reaches the maximum rotation angle relative to the stationary contact 33.

[0067] In some embodiments, Figure 6 As shown, when the moving contact 31 reaches the limit position, the side of the moving contact 31 away from the static contact 33 contacts the first groove bottom 133 of the first groove 132, and the first groove bottom 133 is opposite to the opening of the first groove 132; the lower end of the anti-reverse spraying member 32 is located at the lower side of the second groove bottom 143 of the second groove 142, and the second groove bottom 143 is opposite to the opening of the second groove 142. At this time, since the upper part of the first opening 12 is blocked by the passive contact 31, and the lower part of the first opening 12 is blocked by the anti-reverse spraying member 32, when the high-temperature free gas is ejected in the opposite direction toward the first opening 12 when the arc is generated, it will be completely blocked by the matching moving contact 31 and the anti-reverse spraying member 32, so that the metal support of the moving contact 31 can be prevented from being burned, ensuring the switching performance and service life of the product.

[0068] In some embodiments of the present application, Figure 8 As shown, the width of the back-spray prevention member 32 is greater than or equal to the width of the first opening 12 , wherein the width direction of the first opening 12 is parallel to the rotation axis of the movable contact member 31 .

[0069] exist Figure 8In the figure, the width of the first opening 12 is marked as W1, and the width of the anti-backspray component 32 is marked as W2, W1≤W2, so the anti-backspray component 32 can completely block the first opening 12 in the width direction, thereby preventing the high-temperature free gas from flowing back out of the first opening 12 when an arc is generated and burning other mechanisms or components in the circuit breaker 100.

[0070] In some embodiments of the present application, Fig. 9 As shown, the movable contact 31 includes a rotating portion 311 and a contact portion 312 .

[0071] The rotating part 311 is located on the side of the back-spray prevention member 32 away from the limiting wall 11, and is connected to the back-spray prevention member 32. Generally speaking, the rotating part 311 and the back-spray prevention member 32 are both insulating structures. The rotating part 311 also rotates with the base 1 to realize the rotation of the moving contact member 31 relative to the base 1, such as Fig.10 As shown, a second opening 3111 is formed on the rotating portion 311 , and the second opening 3111 is used to allow one end of the contact portion 312 to extend into the interior of the rotating portion 311 .

[0072] The contact part 312 is a structure in the moving contact 31 for contacting and cooperating with the stationary contact 33. Generally speaking, the contact part 312 adopts a conductive structure, such as a metal contact. One end of the contact part 312 extends into the interior of the rotating part 311 through the second opening 3111 and is fixedly connected to the rotating part 311. The contact part 312 can be directly connected to the inner wall of the rotating part 311, or indirectly connected to the rotating part 311 through parts such as a connecting rod and a rotating shaft. The other end of the contact part 312 is located in the arc extinguishing chamber 21, and is used for contacting and cooperating with the stationary contact 33.

[0073] Alternatively, if Fig.10 As shown, the rotating part 311 and the anti-reverse spraying part 32 are an integrally formed structure. That is, the rotating part 311 and the anti-reverse spraying part 32 are made by an integrally formed process, so that the two have better structural strength and other mechanical properties, and improve the processing and manufacturing efficiency of the whole part.

[0074] In some embodiments of the present application, the moving contact 31 further includes an insulating protection portion 313, which is used to protect at least one of the contact portion 312 and the anti-reverse spraying member 32 when the arc is reversely sprayed. Specifically, the insulating protection portion 313 has better high-temperature ablation resistance, and is located on the side of the moving contact 31 and the anti-reverse spraying member 32 close to the static contact 33, which can separate the arc in the arc extinguishing chamber 21 from the contact portion 312 and the anti-reverse spraying member 32 to a certain extent, thereby preventing the high-temperature free gas from directly ablating the contact portion 312 and the anti-reverse spraying member 32.

[0075] Alternatively, if Fig. 9As shown, the insulating protection portion 313 wraps at least a portion of the surface of the contact portion 312 facing the stationary contact 33 to prevent the arc from being transmitted backward through the contact portion 312 and burning other components in the circuit breaker 100 .

[0076] Optionally, continue to see Fig. 9 The insulating protection portion 313 also wraps at least a portion of the surface of the back-spray prevention component 32 facing the first opening 12 , thereby improving the arc blocking effect of the back-spray prevention component 32 .

[0077] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application 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 application. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0078] The above description is only for the purpose of facilitating those skilled in the art to understand the technical solution of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A circuit breaker, characterized in that: The circuit breaker comprises a base (1), and an arc extinguishing mechanism (2) and a contact mechanism (3) installed inside the base (1); The base (1) has a limiting wall (11) inside, the limiting wall (11) is used to enclose the installation position of the arc extinguishing mechanism (2), and the limiting wall (11) is provided with a first opening (12); An arc extinguishing chamber (21) is formed in the arc extinguishing mechanism (2), and an inlet (211) of the arc extinguishing chamber (21) is connected to the first opening (12); The contact mechanism (3) comprises a moving contact (31) and an anti-backspraying member (32); the moving contact (31) is rotatably connected to the base (1), and one end of the moving contact (31) passes through the first opening (12) and the entrance (211) of the arc extinguishing chamber (21) and is located in the arc extinguishing chamber (21); the anti-backspraying member (32) is located on a side of the limiting wall (11) away from the arc extinguishing mechanism (2) and is connected to the moving contact (31); the anti-backspraying member (32) is configured to cooperate with the moving contact (31) to block at least a portion of the first opening (12).

2. The circuit breaker according to claim 1, characterized in that: The surface of the limiting wall (11) away from the arc extinguishing mechanism (2) has a first curved surface (111), and the surface of the back-spray prevention component (32) facing the limiting wall (11) has a second curved surface (321); The circle where the first arc surface (111) is located and the circle where the second arc surface (321) is located are concentric circles, and the centers of the concentric circles are located on the rotation axis of the moving contact member (31).

3. The circuit breaker according to claim 2, characterized in that: The base (1) comprises a first seat portion (13) and a second seat portion (14) which are detachably connected; The first seat portion (13) has a first wall (131), a first groove (132) is provided on the first wall (131), and the first groove (132) opens toward the second seat portion (14); The second seat portion (14) has a second wall body (141), the second wall body (141) and the first wall body (131) constitute the limiting wall (11), the first arc surface (111) is located on the second wall body (141), and the second wall body (141) is provided with a second groove (142), and the second groove (142) is connected with the first groove (132) to enclose the first opening (12).

4. The circuit breaker according to claim 3, characterized in that: The contact mechanism (3) further comprises a stationary contact (33), wherein the stationary contact (33) and the moving contact (31) can be in contact and fit in the arc extinguishing chamber (21); When the moving contact (31) is in the extreme position, the side of the moving contact (31) facing away from the static contact (33) contacts the first groove bottom (133) of the first groove (132), and the lower end of the anti-backspraying member (32) is located at the lower side of the second groove bottom (143) of the second groove (142), wherein the extreme position is the position where the moving contact (31) reaches the maximum rotation angle relative to the static contact (33).

5. The circuit breaker according to claim 3, characterized in that: The tangent direction of the first curved surface (111) on one side close to the first seat portion (13) is parallel to the length direction of the first opening (12); and / or the length direction of the first opening (12) is parallel to the height direction of the base (1).

6. The circuit breaker according to claim 1, characterized in that: The back-spray prevention component (32) is located on the lower side of the moving contact (31), and the orthographic projection of the lower end of the back-spray prevention component (32) on the opening plane of the first opening (12) is located on the lower side of the first opening (12), wherein the lower side of the moving contact (31) is the side of the moving contact (31) close to the static contact (33) in the contact mechanism (3).

7. The circuit breaker according to claim 1, characterized in that: The width of the back-spray prevention member (32) is greater than or equal to the width of the first opening (12), and the width direction of the first opening (12) is parallel to the rotation axis of the movable contact member (31).

8. The circuit breaker according to claim 1, characterized in that: The moving contact (31) comprises a rotating part (311) and a contact part (312); The rotating part (311) is located on a side of the back-spray prevention component (32) away from the limiting wall (11) and is connected to the back-spray prevention component (32). The rotating part (311) is rotatably matched with the base (1), and a second opening (3111) is formed on the rotating part (311); One end of the contact part (312) extends into the interior of the rotating part (311) through the second opening (3111) and is connected to the rotating part (311), and the other end of the contact part (312) is located in the arc extinguishing chamber (21).

9. The circuit breaker according to claim 8, characterized in that: The rotating part (311) and the back-spray prevention component (32) are an integrally formed structure.

10. The circuit breaker according to claim 8 or 9, characterized in that: The moving contact (31) further comprises an insulating protection portion (313), wherein the insulating protection portion (313) is located on a side of the moving contact (31) and the back-spray prevention portion (32) close to the stationary contact (33) in the contact mechanism (3), wherein: The insulating protection portion (313) wraps at least a portion of the surface of the contact portion (312) facing the stationary contact (33); and / or, The insulating protection portion (313) wraps at least a portion of the surface of the back-spray prevention component (32) facing the first opening (12).

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