Circuit breaker

Abstract

The utility model discloses a circuit breaker which at least comprises one pole of circuit breaker unit, and each pole of circuit breaker unit comprises a circuit breaker shell. Wherein the two side surfaces of the circuit breaker shell in the first direction are locally sunken to form a groove and two blocking walls, and the two blocking walls are arranged on the two sides of the groove in the second direction of the circuit breaker shell respectively; threading holes are formed in the two side surfaces of the circuit breaker shell in the first direction, and the threading holes are located in the grooves; the cable has the advantages of being stable in structure and large in creepage distance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of low-voltage electrical apparatus, in particular to a circuit breaker. BACKGROUND

[0002] Miniature circuit breakers can be classified into single-pole circuit breakers and multi-pole circuit breakers according to the number of poles.

[0003] In order to be connected to a circuit, the circuit breaker needs to have wires or bus bars inserted into the wire insertion holes of the circuit breaker. The wire insertion holes of adjacent poles of the existing multi-pole circuit breaker are relatively close, and therefore an additional phase spacing plate is often needed.

[0004] For example, CN212392188U discloses a circuit breaker, in which the wire insertion holes of each pole circuit breaker are formed on the side surface of the shell of each pole circuit breaker and are flush with the side surface. The wire insertion holes of adjacent pole circuit breakers are very close to each other, and therefore an additional phase spacing plate is needed.

[0005] Although this type of phase spacing plate can solve the problem of the creepage distance of adjacent pole circuit breakers, it also has other problems. For example, the change in direction of the phase spacing plate increases the overall length of the circuit breaker, making the circuit breaker too long. In addition, in actual use, the phase spacing plate may fall off due to improper installation structure or loose assembly structure between the two, which makes it difficult to increase the creepage distance.

[0006] Therefore, how to design a circuit breaker that does not need an additional phase spacing plate and can improve the creepage distance is a problem worth considering. SUMMARY

[0007] Therefore, the purpose of the present application is to overcome the shortcomings of the prior art and provide a reclosing circuit breaker.

[0008] The present application provides a circuit breaker, which comprises at least one pole circuit breaker unit, each pole circuit breaker unit comprising a circuit breaker shell; wherein two side surfaces of the circuit breaker shell in a first direction are partially recessed to form a groove and two blocking walls, the two blocking walls being arranged on the two sides of the groove in a second direction of the circuit breaker shell; and the two side surfaces of the circuit breaker shell in the first direction are provided with wire insertion holes, and the wire insertion holes are located in the groove.

[0009] In some embodiments of the present application, in the first direction of the circuit breaker shell, the distance between the blocking wall and the bottom of the groove is not less than 2mm.

[0010] In some embodiments of the present application, in the second direction of the circuit breaker shell, the thickness of the blocking wall is not less than 1.2mm.

[0011] In some embodiments of the present application, the two side surfaces of the circuit breaker housing in the first direction are respectively a left side wall and a right side wall; the groove and the two blocking walls on the left side wall are respectively a left groove, a left first blocking wall and a left second blocking wall, and the groove and the two blocking walls on the right side wall are respectively a right groove, a right first blocking wall and a right second blocking wall; the left groove and the right groove are both communicated to the bottom surface of the circuit breaker housing.

[0012] In some embodiments of the present application, the right groove is provided with an adjusting screw hole; in the third direction of the circuit breaker housing, the adjusting screw hole is below the threading hole in the right groove.

[0013] In some embodiments of the present application, the right groove is provided with a buckle mounting hole; in the third direction of the circuit breaker housing, the buckle mounting hole is below the threading hole in the right groove.

[0014] In some embodiments of the present application, the left groove is provided with an exhaust hole, the circuit breaker housing has an arc extinguishing chamber, and the exhaust hole is communicated to the rear end of the arc extinguishing chamber; in the third direction of the circuit breaker housing, the exhaust hole is below the threading hole in the left groove.

[0015] In some embodiments of the present application, the circuit breaker housing comprises a first half housing and a second half housing, the left first blocking wall and the right first blocking wall are arranged on the first half housing, and the left second blocking wall and the right second blocking wall are arranged on the second half housing; the first and second half housings are fixed by buckles and / or rivets, and after being fixed, the first and second half housings jointly form the left groove and the right groove.

[0016] In some embodiments of the present application, the inside of the circuit breaker housing comprises an operating mechanism, a moving contact, a stationary contact and a thermal release; the operating mechanism comprises a handle, a connecting rod, a bracket, a lock catch, a trip catch and a main spring; the handle and the bracket are both rotationally arranged in the circuit breaker housing, and the handle is connected to the trip catch through the connecting rod; the trip catch and the lock catch are both rotationally arranged on the bracket, and there is a locking state and an unlocking state between the trip catch and the lock catch; the main spring is connected between the bracket and the circuit breaker housing, and the moving contact is connected to the bracket; when the circuit breaker is in a closed state, the trip catch and the lock catch are in the locking state to make the moving contact and the stationary contact remain in a contact state; the thermal release comprises a bimetallic strip and a pull rod, and the bimetallic strip is part of a circuit breaker main circuit conductor; one end of the pull rod is connected to the lock catch, and the other end is located near the movable end of the bimetallic strip; when the main circuit is overloaded, the bimetallic strip is heated and bent, the movable end drives the lock catch to be unlocked through the pull rod, so that the operating mechanism trips.

[0017] In some embodiments of the present application, the pull rod comprises a transverse portion, a first bent portion for cooperating with the bimetallic strip, and a second bent portion for connecting with the lock catch, the first bent portion and the second bent portion being connected by the transverse portion; the first half shell comprises a main panel, one side of the main panel facing the second half shell being a first surface, and the other side of the main panel away from the second half shell being a second surface; a slide groove and a blocking portion are formed on the first surface, the slide groove being divided into a first slide groove section, a transition slide groove section blocked by the blocking portion, and a second slide groove section in sequence along the length direction L of the slide groove; the transverse portion is slidingly arranged in the slide groove and is blocked by the blocking portion to prevent the pull rod from falling out of the slot of the slide groove; a mounting avoiding hole is formed on the second surface and communicates with the first slide groove section and the second slide groove section; during mounting, the first bent portion is inserted into the mounting avoiding hole from the first slide groove section, and then the first bent portion is inserted back into the second slide groove section through the mounting avoiding hole after the first bent portion completely passes over the blocking portion, so as to realize the mounting of the pull rod.

[0018] The present application has the following beneficial effects compared with the prior art:

[0019] Since the multi-pole circuit breaker is generally arranged in the second direction (width direction D) of the circuit breaker unit, the recess and the two blocking walls are equivalent to two phase spacing plates integrally formed on the circuit breaker shell, which are located on both sides of the threading hole. Therefore, the circuit breaker does not need to additionally increase the phase spacing plates, and the possibility of the phase spacing plates falling off is avoided, thereby ensuring the creepage distance.

[0020] Secondly, the structure formed by the local recess on the side surface of the circuit breaker shell does not increase the length of the circuit breaker shell itself, and the increase in the overall length of the circuit breaker caused by the additional phase spacing plates is avoided. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation to the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor.

[0022] Figure 1 A schematic view of the circuit breaker of the embodiment of the present application is shown;

[0023] Figure 2 A schematic view of the circuit breaker unit of the embodiment of the present application is shown;

[0024] Figure 3 A schematic view of another view of the circuit breaker unit of the embodiment of the present application is shown;

[0025] Figure 4 Figure 7 shows a schematic view of the circuit breaker unit of the present application after the second half shell is removed;

[0026] Figure 5 Figure 8 shows a schematic view of the cooperation between the pull rod and the first half shell in the circuit breaker unit of the present application;

[0027] Figure 6 Figure 9 shows an enlarged view of the sliding groove in the circuit breaker unit of the present application. DETAILED DESCRIPTION

[0028] Embodiments of the present application are described below in detail, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only, and are used only for explaining the present application, and cannot be understood as a limitation of the present application.

[0029] In the description of the present application, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship 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, and are not intended to indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0030] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified and limited.

[0031] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature. Example

[0033] like Figures 1-6 As shown, an embodiment of this application is a circuit breaker.

[0034] In this embodiment, a 4-pole circuit breaker is used, which includes a 4-pole circuit breaker unit P. Since the structure of each pole circuit breaker unit P is the same, one pole will be described in detail. The structure of the other poles can be found in the structure of that pole.

[0035] The circuit breaker unit P includes a circuit breaker housing 100 and two sets of terminals 200 located inside the housing, a main circuit conductor, an operating mechanism, an electromagnetic mechanism, an arc-extinguishing chamber, and a thermal trip unit.

[0036] Both sets of terminal blocks 200 adopt a screw-connection structure, including components such as a terminal block frame and terminal screws. The terminal block frame is used to pass wires or busbars through (wires are passed through the wire hole 110 into the terminal block frame), and the terminal screws are used to tighten the wires or busbars.

[0037] The main circuit conductors include terminal blocks that pass through the two wiring frames, a solenoid (part of the electromagnetic mechanism), a stationary contact 303, a moving contact 304, and a bimetallic strip 301 (part of the thermal trip unit). The connection method of these main circuit conductors is conventional and will not be described in detail here.

[0038] The operating mechanism includes a handle, a linkage, a bracket, a latch 401, a jump latch 402, and a main spring.

[0039] The handle is rotatably connected to the circuit breaker housing 100 via a hinge shaft, and one end of the handle extends out of the circuit breaker housing 100 for user operation.

[0040] The bracket and the circuit breaker housing 100 are rotatably connected by another hinge shaft, and one end of the bracket is abutted against the circuit breaker housing 100 by a main spring (compression spring).

[0041] The jumper 402 is rotatably connected with the bracket through its own rotating shaft, and the lock catch 401 is rotatably connected with the bracket through the hinge shaft of the bracket. The jumper 402 has a first lapping part, and the lock catch 401 has a second lapping part. The first lapping part and the second lapping part have two states. One state is that the two form lapping so that the jumper 402 and the lock catch 401 form a locking state, and the other state is that the two do not form lapping so that the jumper 402 and the lock catch 401 form an unlocking state.

[0042] The handle is connected with the jumper 402 through a connecting rod. When the handle is rotated towards the closing direction, the lock catch 401 and the jumper 402 can be changed from the unlocking state to the locking state, and the bracket can be rotated when the handle is driven again. Since the movable contact 304 is arranged on the bracket, the movable contact 304 can be in contact with the static contact 303 with the rotation of the bracket, so that the closing of the circuit breaker is realized.

[0043] The above operating mechanism is a conventional technical means in the art, and will not be described in detail here.

[0044] The arc extinguishing chamber is used to extinguish the arc generated when the movable contact 304 is separated from the static contact 303.

[0045] The electromagnetic mechanism adopts the principle of electromagnet, but when the main circuit conductor has a short circuit fault, the electromagnetic mechanism actuates the lock catch 401 and the jumper 402 to be in the unlocking state, so that the operating mechanism trips (the movable contact 304 is separated from the static contact 303).

[0046] The thermal release includes a bimetallic strip 301 and a pull rod 302. One end of the pull rod 302 is connected with the lock catch 401, and the other end is located near the movable end of the bimetallic strip 301. When the main circuit is overloaded, the bimetallic strip 301 is heated and bent, and the movable end drives the lock catch 401 to be unlocked through the pull rod 302, so that the operating mechanism trips (the movable contact 304 is separated from the static contact 303).

[0047] In the embodiment, the circuit breaker housing 100 includes a first half housing 101 and a second half housing 102. The first half housing 101 and the second half housing 102 are fixed by riveting and buckling. The above-mentioned elements are arranged in the space formed by the two half housings. Of course, the riveting and buckling here can also use only one of the fixing methods.

[0048] On the first half housing 101, there is a sliding groove 1010 for guiding the transverse movement of the pull rod 302. Specifically, the first half housing 101 includes a main panel 101a. One side of the main panel 101a facing the second half housing 102 is a first surface 101a1, and the other side away from the second half housing 102 is a second surface 101a2. The sliding groove 1010 is arranged on the first surface 101a1, and a blocking part 1011 is arranged on the first surface 101a1.

[0049] The pull rod 302 is in a U-shaped structure, including a horizontal moving part 302a, a first bending part 302b and a second bending part 302c, the first bending part 302b and the second bending part 302c are adjacent through the horizontal moving part 302a. Here, the horizontal moving part 302a is arranged in the sliding groove 1010, the first bending part 302b is used to cooperate with the bimetallic strip 301, and the second bending part 302c is used to be connected with the lock catch 401. Since the blocking part 1011 is arranged at the slot side of the sliding groove 1010, the blocking part 1011 can block the horizontal moving part 302a from falling off, that is, prevent the pull rod 302 from falling off from the slot of the sliding groove 1010.

[0050] Specifically, the sliding groove 1010 is sequentially divided into a first sliding groove section 1010a, a transition sliding groove section 1010b blocked by the blocking part 1011 and a second sliding groove section 1010c along the length direction L thereof. The second surface 101a2 is provided with a mounting avoiding hole 1012, which is in communication with the first sliding groove section 1010a and the second sliding groove section 1010c. During installation, the first bending part 302b is inserted into the mounting avoiding hole 1012 from the first sliding groove section 1010a, the pull rod 302 is continuously pushed in until the first bending part 302b completely passes the blocking part 1011, and then the first bending part 302b is inclined towards the mounting avoiding hole 1012 and inserted back into the second sliding groove section 1010c, so that the horizontal moving part 302a is completely in the sliding groove 1010, the installation of the pull rod 302 is completed, and the blocking part 1011 blocks the horizontal moving part 302a.

[0051] The structure of the above-mentioned blocking part 1011 and mounting avoiding hole 1012 not only ensures that the pull rod 302 can be normally assembled, but also ensures that the assembled pull rod 302 can be stably arranged on the first half shell 101.

[0052] The two side surfaces in the first direction L of the circuit breaker shell 100 are both partially recessed to form a groove and two blocking walls. The two side surfaces in the first direction L can be understood as the left side wall 100a and the right side wall 100b, in order to distinguish the formed groove and blocking wall. The groove and the two blocking walls on the left side wall 100a are respectively a left groove 100a1, a left first blocking wall 100a2 and a left second blocking wall 100a3, and the groove and the two blocking walls on the right side wall 100b are respectively a right groove 100b1, a right first blocking wall 100b2 and a right second blocking wall 100b3.

[0053] Since the circuit breaker housing 100 is divided into a first half shell 101 and a second half shell 102. Here, the left first barrier wall 100a2 and the right first barrier wall 100b2 are arranged on the first half shell 101, and the left first barrier wall 100a2 and the right first barrier wall 100b2 are arranged on the first half shell 101. And the left groove 100a1 and the right groove 100b1 are formed after the two half shells are matched.

[0054] Here, the two wire holes 110 are respectively in the two grooves, that is, one wire hole 110 is arranged on the groove bottom of the left groove 100a1, and the other wire hole 110 is arranged on the groove bottom of the right groove 100b1. For the wire hole 110 on the left groove 100a1, the two sides in the second direction are respectively the left first barrier wall 100a2 and the left second barrier wall 100a3; for the wire hole 110 on the right groove 100b1, the two sides in the second direction are respectively the right first barrier wall 100b2 and the right second barrier wall 100b3.

[0055] Through such a structure of locally recessing grooves and barrier walls, the barrier wall between the two adjacent pole circuit breaker units P plays the role of the existing technology of the inter-spacing plate, and the barrier wall belongs to part of the circuit breaker housing 100, without subsequent installation.

[0056] In the first direction L (length direction L) of the circuit breaker housing 100, the distance between the left first barrier wall 100a2, the left second barrier wall 100a3 and the groove bottom of the left groove 100a1 is not less than 2mm. The distance between the right first barrier wall 100b2, the right second barrier wall 100b3 and the groove bottom of the right groove 100b1 is not less than 2mm, which can effectively ensure the creepage distance.

[0057] In the second direction (width direction D) of the circuit breaker housing 100, the thickness dimension of the left first barrier wall 100a2, the left second barrier wall 100a3, the right first barrier wall 100b2 and the right second barrier wall 100b3 is not less than 1.2mm, which can effectively ensure the strength of the barrier wall.

[0058] Whether it is the left groove 100a1 or the right groove 100b1, it extends to the bottom surface of the circuit breaker housing 100, that is, it communicates with the bottom surface of the circuit breaker housing 100, which is beneficial to the injection molding of the shell.

[0059] In the third direction (height direction H) of the circuit breaker housing 100, the groove bottom of the right groove 100b1 is also provided with an adjusting screw hole 120, which is used to set the adjusting screw of the thermal release. Here, the adjusting screw hole 120 is below the wire hole 110 in the right groove 100b1, which is beneficial to the setting of the adjusting screw.

[0060] In the third direction (height direction H) of the circuit breaker housing 100, a buckle mounting hole 130 is further formed in the groove bottom of the right groove 100b1, and the buckle mounting hole 130 is used to mount a buckle (not shown). After the buckle is mounted, the circuit breaker can be fixed on the DIN rail through the buckle. Here, the buckle mounting hole 130 is located below the adjusting screw hole 120 and below the threading hole 110 in the right groove 100b1. Such a structure is conducive to the installation of the buckle.

[0061] In the third direction (height direction H) of the circuit breaker housing 100, an exhaust hole 140 is formed in the groove bottom of the left groove 100a1. The exhaust hole 140 is connected to the inside of the circuit breaker housing 100, specifically to the arc-extinguishing chamber where the arc-extinguishing chamber is located. In this way, the gas from the arc-extinguishing chamber can be discharged to the outside of the circuit breaker housing 100 through the exhaust hole 140. Here, the exhaust hole 140 is located below the threading hole 110 in the left groove 100a1. Such a structure is conducive to the exhaust.

[0062] The above structure is not limited to be applied to the ordinary circuit breaker (air switch), but can also be applied to the residual current circuit breaker or the reclosing circuit breaker.

[0063] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the different embodiments or examples described in the present specification and the features of the different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0064] Although the embodiments of the present application have been shown and described above, it should be understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A circuit breaker comprising at least one pole circuit breaker unit, each pole circuit breaker unit comprising a circuit breaker housing; characterized by: Both side surfaces of the circuit breaker shell in the first direction are partially recessed to form a groove and two blocking walls, the two blocking walls are separately arranged on both sides of the groove in the second direction of the circuit breaker shell; both side surfaces of the circuit breaker shell in the first direction are provided with a threading hole, and the threading hole is located in the groove.

2. The circuit breaker of claim 1, wherein: In the first direction of the circuit breaker shell, the distance between the blocking wall and the groove bottom is not less than 2mm.

3. The circuit breaker of claim 1, wherein: In the second direction of the circuit breaker shell, the thickness dimension of the blocking wall is not less than 1.2mm.

4. The circuit breaker of claim 1, wherein: Both side surfaces of the circuit breaker shell in the first direction are respectively left and right side walls; the groove and the two blocking walls on the left side wall are respectively a left groove, a left first blocking wall and a left second blocking wall, and the groove and the two blocking walls on the right side wall are respectively a right groove, a right first blocking wall and a right second blocking wall; the left groove and the right groove are both communicated to the bottom surface of the circuit breaker shell.

5. The circuit breaker of claim 4, wherein: The right groove is provided with an adjusting screw hole; in the third direction of the circuit breaker shell, the adjusting screw hole is below the threading hole in the right groove.

6. The circuit breaker of claim 4, wherein: The right groove is provided with a buckle mounting hole; in the third direction of the circuit breaker shell, the buckle mounting hole is below the threading hole in the right groove.

7. The circuit breaker of claim 4 wherein: The left groove is provided with an exhaust hole, and the circuit breaker shell has an arc extinguishing chamber, the exhaust hole is communicated with the rear end of the arc extinguishing chamber; in the third direction of the circuit breaker shell, the exhaust hole is below the threading hole in the left groove.

8. The circuit breaker of claim 4, wherein: The circuit breaker shell comprises a first half shell and a second half shell, the left first blocking wall and the right first blocking wall are arranged on the first half shell, and the left second blocking wall and the right second blocking wall are arranged on the second half shell; the first and second half shells are fixed by buckles and / or rivets, and after being fixed, the first and second half shells jointly form the left groove and the right groove.

9. The circuit breaker of claim 8, wherein: The inside of the circuit breaker shell comprises an operating mechanism, a moving contact, a static contact and a thermal release; the operating mechanism comprises a handle, a connecting rod, a bracket, a lock catch, a trip catch and a main spring; the handle and the bracket are both rotationally arranged in the circuit breaker shell, and the handle is connected with the trip catch through the connecting rod; the trip catch and the lock catch are both rotationally arranged on the bracket, and there are a locking state and an unlocking state between the trip catch and the lock catch; the main spring is connected between the bracket and the circuit breaker shell, and the moving contact is connected to the bracket; when the circuit breaker is in a closed state, the trip catch and the lock catch are in the locking state to make the moving contact and the static contact remain in a contact state; the thermal release comprises a bimetallic strip and a pull rod, the bimetallic strip is part of a circuit breaker main circuit conductor; one end of the pull rod is connected with the lock catch, and the other end is located near the movable end of the bimetallic strip, and when the main circuit is overloaded, the bimetallic strip is heated and bent, the movable end drives the lock catch to be unlocked through the pull rod, so that the operating mechanism trips.

10. The circuit breaker of claim 9, wherein: The pull rod comprises a horizontal moving part, a first bending part and a second bending part, the first bending part is used for cooperating with the bimetallic strip, the second bending part is used for being connected with the lock catch, and the first bending part and the second bending part are connected through the horizontal moving part; the first half shell comprises a main panel, one side of the main panel facing the second half shell is a first surface, and the other side of the main panel away from the second half shell is a second surface; a sliding groove and a blocking part are arranged on the first surface, the sliding groove is sequentially divided into a first sliding groove section, a transition sliding groove section blocked by the blocking part and a second sliding groove section along a length direction L of the sliding groove; the horizontal moving part is slidingly arranged in the sliding groove and is blocked by the blocking part to prevent the pull rod from falling off from a slot of the sliding groove; a mounting avoiding hole is arranged on the second surface and communicates with the first sliding groove section and the second sliding groove section; during mounting, the first bending part is inserted into the mounting avoiding hole from the first sliding groove section, and then the first bending part is inserted back into the second sliding groove section through the mounting avoiding hole after the first bending part completely passes the blocking part, so that the pull rod is mounted.

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