Circuit breaker with simplified tripper

Abstract

The invention belongs to the technical field of low-voltage electric appliances, and particularly relates to a circuit breaker with a simplified tripper, which comprises a circuit breaker main body, a detachably connected tripper mounting mechanism is arranged in the circuit breaker main body, and limiting mechanisms are arranged on two side walls of the circuit breaker main body. According to the invention, the sleeve, the coil, the first through cavity, the static iron core, the movable iron core, the second through cavity, an ejector rod, a limiting plate, a spring, a convex shaft, a groove, a convex ring and a lantern ring are used in a clearance fit manner, the ejector rod can be driven by the limiting plate through the static iron core and the movable iron core, and the groove formed in the top of the ejector rod is in insertion fit with the convex shaft on the outer wall of the movable iron core; meanwhile, the top plate is arranged in the second through cavity in the static iron core, the movable iron core, the static iron core and the sleeve can be installed at the same time, the installation process of the release is facilitated, meanwhile, the structure is detachable, installation is more convenient, the structure is simple, practicability is high, and the requirements are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-voltage electrical appliances, and particularly relates to a circuit breaker with a simplified release. Background Art

[0002] The circuit breaker has the characteristics of advanced structure, reliable performance, strong breaking capacity, beautiful and compact appearance, etc. It is used for overloading and short-circuit protection of lighting, power distribution lines and equipment in office buildings, residences and similar buildings, and can also be used for infrequent on-off operation and conversion of lines.

[0003] In the design of traditional circuit breakers, the release often has a complex structure. It usually includes multiple mechanical components and electronic elements for realizing the tripping action in case of faults such as overload and short circuit. With the development of electronic technology, especially the wide application of integrated circuits and microcontrollers, it has become possible to design a more compact and precise release, which aims to reduce unnecessary mechanical components, improve the reliability and stability of the release, and at the same time reduce the volume of the circuit breaker.

[0004] Most of the circuit breakers with simplified releases used in the prior art have a release, and the structure of its release includes parts such as a skeleton, a yoke, a push rod, a moving iron core, a static iron core, and a spring. The structure adopted during use is relatively complex, and the installation of the structure is rather troublesome. At the same time, it is difficult to have convenient disassembly and assembly during the installation of the circuit breaker. Therefore, a new type of circuit breaker with a simplified release is needed to improve the above-mentioned device. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a circuit breaker with a simplified release. To achieve the above purpose, the problem that the existing circuit breaker with a simplified release is inconvenient to install, has a complex structure for the internal release components, and is not convenient for disassembly and maintenance is solved.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A circuit breaker with a simplified release, including a circuit breaker main body, and a release installation mechanism which is detachably connected is arranged inside the circuit breaker main body, and limiting mechanisms are arranged on both side walls of the circuit breaker main body;

[0007] The release installation mechanism includes a sleeve, a coil, a first through cavity, a static iron core, a moving iron core, a second through cavity, a push rod, a limiting plate and a spring. The outer surface of the sleeve is sleeved and connected with a coil. The inner cavity of the sleeve is axially provided with a first through cavity. The static iron core is arranged in the sleeve and is in clamping fit with the inner wall of the first through cavity. The inner part of the static iron core is axially provided with a second through cavity. The moving iron core is in clearance fit with the first through cavity. The push rod is embedded and installed in the inner cavity of the static iron core. One end of the push rod abuts against the side wall of the moving iron core. The other end of the push rod penetrates through the second through cavity and is detachably installed with a limiting plate. A spring is further arranged between the outer wall of the moving iron core in the axial direction and the static iron core.

[0008] As a preferred solution, the release installation mechanism further includes a first connecting frame, a second connecting frame, a first receiving groove and a second receiving groove. The first connecting frame and the second connecting frame are arranged in the circuit breaker body. Both the first connecting frame and the second connecting frame include a bottom plate and mounting bolts. The four corners of the upper end surface of the bottom plate are connected with mounting bolts. The bottoms of the first connecting frame and the second connecting frame are fixedly connected with the bottom plate. The first connecting frame is provided with a first receiving groove, and the second connecting frame is provided with a second receiving groove.

[0009] As a preferred solution, the moving iron core is provided with a convex shaft, and one end of the push rod is provided with a groove that is in clamping fit with the convex shaft.

[0010] As a preferred solution, the limiting mechanism includes a sliding member and a fastening member. The two side walls of the circuit breaker body are fixedly connected with the fastening member. The sliding member is slidably arranged inside the fastening member. The fastening member includes a connecting plate, a mounting groove, a sliding groove, a sliding plate, a sliding block, a mounting plate and a pin hole. The two side walls of the circuit breaker body are fixedly connected with the connecting plate through bolts. The inner cavity of the connecting plate is provided with a mounting groove, and the two side walls are provided with sliding grooves. The mounting groove is communicated with the sliding groove. A sliding plate is slidably connected inside the connecting plate. The outer wall of the sliding plate is fixedly connected with a mounting plate. The mounting plate is provided with a pin hole. The two side walls of the sliding plate are fixedly connected with sliding blocks, and the sliding blocks are in sliding contact with the sliding grooves.

[0011] As a preferred solution, the fastening member includes a limiting hole and an adjusting bolt. A number of uniformly distributed limiting holes are opened on both sides of the outer wall of the connecting plate. An adjusting bolt is arranged on the upper end surface of the connecting plate. The adjusting bolt is slidably arranged in the limiting hole and extends through to the inner wall of the sliding block.

[0012] As a preferred solution, the bottom of the mounting plate is fixedly connected with a clamping block. The clamping block is provided with an inclined surface, and the inclination angle of the inclined surface is 30 - 70 degrees.

[0013] As a preferred solution, the diameter of the first receiving groove is greater than that of the second receiving groove. The first receiving groove is in clamping fit with the outer wall of the sleeve. A collar is provided at the connection between one end of the static iron core and the outer wall of the sleeve. The second receiving groove is in clamping fit with the outer wall of the collar.

[0014] As a preferred solution, a convex ring is provided on the inner wall of the second through cavity. One end of the spring is arranged in the second through cavity and its bottom presses against the convex ring.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects:

[0016] 1. In the present invention, through the gap fit of the sleeve, coil, first through cavity, static iron core, moving iron core, second through cavity, ejector rod, limiting plate, spring, convex shaft, groove, convex ring and collar, the static iron core and the moving iron core can drive the ejector rod by means of the limiting plate. The groove formed at the top of the top plate is in plug-in fit with the convex shaft on the outer wall of the moving iron core. At the same time, the top plate is arranged in the second through cavity of the static iron core, so that the moving iron core, the static iron core and the sleeve can be installed simultaneously, which facilitates the installation process of the release. At the same time, the structure is detachable, the installation is more convenient, the structure is simple, and the practicability is strong.

[0017] 2. When the present invention is in use, the installation of the circuit breaker body can be facilitated through the provided limiting mechanism. Through the sliding of the sliding plate in the connecting plate, the positioning effect can be achieved by using the adjusting bolt and the provided limiting holes, which is convenient for the two mounting plates to be limited and fixed when the circuit breaker is installed by using the pin holes formed on the mounting plate. At the same time, the stability is increased by using the clamping block to abut against the inner wall.

[0018] 3. When the present invention is in use, the fixing of both ends of the surface of the sleeve can be realized through the provided first support frame and second support frame. At the same time, the provided bottom plate and mounting bolts can further prevent the release from falling off, greatly improving the stability of the release and meeting the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings incorporated herein and constituting a part of the specification illustrate embodiments of the present disclosure and, together with the specification, are further used to explain the principles of the present disclosure and enable those skilled in the relevant art to implement and use the present disclosure.

[0020] Figure 1 It is a three-dimensional structural schematic diagram of a circuit breaker with a simplified release;

[0021] Figure 2 It is an overall structural dissection diagram of a circuit breaker with a simplified release;

[0022] Figure 3Anatomy diagram of a circuit breaker trip device installation mechanism with a simplified trip device;

[0023] Figure 4 Partial structure schematic diagram of a circuit breaker trip device installation mechanism with a simplified trip device;

[0024] Figure 5 Enlarged view of the structure of Circuit Breaker A with a simplified trip device;

[0025] Figure 6 Another view of the overall structure of a circuit breaker with a simplified trip device;

[0026] Figure 7 Structure diagram of the limit mechanism of a circuit breaker with a simplified trip device.

[0027] [Reference Signs]

[0028] 1. Circuit breaker body; 2. Limit mechanism; 21. Fastener; 22. Sliding part; 201. Connecting plate; 202. Chute; 203. Limit hole; 204. Adjusting bolt; 205. Installation groove; 206. Slide plate; 207. Slide block; 208. Installation plate; 209. Pin hole; 210. Block; 3. Trip device installation mechanism; 301. Sleeve; 302. Moving iron core; 303. Static iron core; 304. Second through cavity; 305. Limit plate; 306. Thrust rod; 307. Convex shaft; 308. Groove; 309. Spring; 310. Convex ring; 311. First through cavity; 312. Collar; 313. Coil; 314. First connecting frame; 315. Base plate; 316. Installation bolt; 317. First receiving groove; 318. Second connecting frame; 319. Second receiving groove.

[0029] As shown in the figure, in order to clearly show the structure of the embodiments of the present invention, specific structures and devices are marked in the figure, but this is only for illustrative purposes and is not intended to limit the present invention to this specific structure, device and environment. According to specific needs, those of ordinary skill in the art can adjust or modify these devices and environments, and the adjustments or modifications made are still included in the scope of the appended claims. Detailed Description of the Invention

[0030] The following describes in detail a circuit breaker with a simplified trip device provided by the present invention in conjunction with the accompanying drawings and specific embodiments. At the same time, it should be noted here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments. For some well-known technologies, those skilled in the art can also adopt other alternative methods for implementation; moreover, the accompanying drawings are only for more specifically describing the embodiments and are not intended to specifically limit the present invention.

[0031] It should be noted that in the specification, the mention of "an embodiment", "embodiment", "exemplary embodiment", "some embodiments", etc. indicates that the described embodiments may include specific features, structures or characteristics, but not necessarily every embodiment includes such specific features, structures or characteristics. Additionally, when describing a specific feature, structure or characteristic in combination with an embodiment, implementing such feature, structure or characteristic in combination with other embodiments (whether explicitly described or not) should be within the knowledge of those skilled in the relevant art.

[0032] Generally, terms can be understood at least in part from their use in context. For example, at least in part depending on the context, the term "one or more" used herein can be used to describe any feature, structure or characteristic in a singular sense, or can be used to describe a combination of features, structures or characteristics in a plural sense. Additionally, the term "based on" can be understood as not necessarily intended to convey a set of exclusive factors, but rather can alternatively, at least in part depending on the context, allow for the existence of other factors that may not be explicitly described.

[0033] It can be understood that the meanings of "on", "above", and "over" in the present disclosure should be construed in the broadest manner, such that "on" not only means "directly on" something, but also includes the meaning of being "on" something with intervening features or layers therebetween, and "above" or "over" not only means "above" or "over" something, but also can include the meaning of being "above" or "over" something with no intervening features or layers therebetween.

[0034] Furthermore, spatial relative terms such as "under", "below", "lower", "above", "upper", etc. are used herein for convenience of description to describe the relationship of one element or feature to another or other elements or features, as shown in the drawings. Spatial relative terms are intended to cover different orientations in the use or operation of the device in addition to the orientation depicted in the drawings. The device can be oriented in other ways, and the spatial relative descriptive terms used herein can be similarly interpreted accordingly.

[0035] Embodiment

[0036] Please refer to Figures 1 to 5 , the present invention provides a technical solution: a circuit breaker with a streamlined release, including a circuit breaker body 1, the circuit breaker body 1 includes a release installation mechanism 3 with a detachable connection, and limiting mechanisms 2 are arranged on both side walls of the circuit breaker body 1;

[0037] The trip unit mounting mechanism 3 includes a sleeve 301, a coil 313, a first through cavity 311, a static iron core 303, a moving iron core 302, a second through cavity 304, a push rod 306, a limiting plate 305 and a spring 309. A coil 313 is sleeved and connected to the outer surface of the sleeve 301. An axial first through cavity 311 is formed in the inner cavity of the sleeve 301. The static iron core 303 is arranged in the sleeve 301 and is in clamping fit with the inner wall of the first through cavity 311. An axial second through cavity 304 is formed inside the static iron core 303. The moving iron core 302 is in clearance fit with the first through cavity 311. A push rod 306 is embedded and installed in the inner cavity of the static iron core 303. One end of the push rod 306 abuts against the side wall of the moving iron core 302. The other end of the push rod 306 penetrates through the second through cavity 304 and is detachably installed with a limiting plate 305. A spring 309 is further arranged between the outer wall of the axial moving iron core 302 and the static iron core 303. The trip unit mounting mechanism 3 further includes a first connecting frame 314, a second connecting frame 318, a first receiving groove 317 and a second receiving groove 319. A first connecting frame 314 and a second connecting frame 318 are arranged in the circuit breaker body 1. Both the first connecting frame 314 and the second connecting frame 318 include a bottom plate 315 and mounting bolts 316. Mounting bolts 316 are connected to the four corners of the upper end surface of the bottom plate 315. The bottoms of the first connecting frame 314 and the second connecting frame 318 are fixedly connected to the bottom plate 315. A first receiving groove 317 is formed in the first connecting frame 314. A second receiving groove 319 is formed in the second connecting frame 318. A convex shaft 307 is arranged on the moving iron core 302. A groove 308 that is in clamping fit with the convex shaft 307 is arranged at one end of the push rod 306. The diameter of the first receiving groove 317 is larger than that of the second receiving groove 319. The first receiving groove 317 is in tight fit with the outer wall of the sleeve 301. A collar 312 is arranged at the connection between one end of the static iron core 303 and the outer wall of the sleeve 301. The second receiving groove 319 is in tight fit with the outer wall of the collar 312. A convex ring 310 is arranged on the inner wall of the second through cavity 304. One end of the spring 309 is arranged in the second through cavity 304 and its bottom presses against the convex ring 310;

[0038] When installing and using, the static iron core 303 is first installed into the sleeve 301 and fixed, and then the spring 309 is installed, and then the moving iron core 302 is placed in the first cavity 311, and then one end of the push rod 306 is extended into the sleeve 301, and the groove 308 opened on the top of the push rod 306 and the convex shaft 307 set on one side of the moving iron core 302 are used to realize the plug-in setting, and then the connection with the moving iron core 302 is realized. At this time, since the diameter of the limit plate 305 is larger than the first cavity 311, and the diameter of the moving iron core 302 is larger than the diameter of the second cavity 304, the moving iron core 302 will not fall out of the sleeve 301, and the installed The sleeve 301 can be installed into the circuit breaker body 1, which is easy to install. At the same time, a group of bottom plates 315 are arranged inside the circuit breaker body 1. The bottom plates 315 are stabilized by installing bolts 316, and the disassembly process can be realized. The two bottom plates 315 are provided with a first connecting frame 314 and a second connecting frame 318. The first receiving groove 317 opened on the first connecting frame 314 can be used to realize the clamping and contact with the outer wall of the sleeve 301. At the same time, the second receiving groove 319 on the second connecting frame 318 can realize the clamping fit with the outer wall of the ring 312, so that stability can be achieved after the sleeve 301 is installed.

[0039] like Figures 6 to 7 As shown, the limiting mechanism 2 includes a sliding member 22 and a fastener 21, the two side walls of the circuit breaker body 1 are fixedly connected with the fastener 21, the sliding member 22 is slidably arranged inside the fastener 21, the fastener 21 includes a connecting plate 201, a mounting groove 205, a slide groove 202, a slide plate 206, a slider 207, a mounting plate 208 and a pin hole 209, the two side walls of the circuit breaker body 1 are fixedly connected with the connecting plate 201 by bolts, the inner cavity of the connecting plate 201 is provided with a mounting groove 205, and the two side walls are provided with a slide groove 202, the mounting groove 205 is connected to the slide groove 202, the connecting plate 201 is slidably connected with the slide plate 206, and the outer wall of the slide plate 206 A mounting plate 208 is fixedly connected, and a pin hole 209 is provided on the mounting plate 208. Slide blocks 207 are fixedly connected to the two side walls of the slide plate 206. The slide blocks 207 are in sliding contact with the slide groove 202. The fastener 21 includes a limiting hole 203 and an adjusting bolt 204. A number of evenly distributed limiting holes 203 are provided on both sides of the outer wall of the connecting plate 201. An adjusting bolt 204 is provided on the upper end surface of the connecting plate 201. The adjusting bolt 204 is slidably set in the limiting hole 203 and extends through and to the inner wall of the slide block 207. A clamping block 210 is fixedly connected to the bottom of the mounting plate 208. A slope is provided on the clamping block 210, and the inclination angle of the slope is 30-70 degrees.

[0040] It should be noted that a set of symmetric mounting plates 208 can be set to achieve position limitation during the installation of the circuit breaker body 1. The set connecting plate 201 and the sliding plate 206 can be in relative sliding contact. The displacement sliding is realized by the slider 207 and the sliding groove 202. Furthermore, the limiting hole 203 and the adjusting bolt 204 are set to limit and fix the slider 207, thereby limiting the length of the sliding part of the mounting plate 208, which is convenient for use in different installation environments. At the same time, the set clamping block 210 can be used to resist and improve the stability after installation. The set pin hole 209 is convenient for plugging. During installation, the position of the pin hole 209 is used, and then the pin rod is further used to complete the limitation, so as to realize the fastening installation of the circuit breaker body 1.

[0041] The working principle of the above embodiment is as follows: When installing and using, first install the static iron core 303 into the sleeve 301 and fix it. Then, after installing the spring 309, one end of the spring 309 away from the groove 308 abuts against the convex ring 310 on the inner wall of the second through cavity 304. Then, the moving iron core 302 is placed into the first through cavity 311, and one end of the ejector rod 306 is extended into the sleeve 301. The groove 308 opened at the top of the ejector rod 306 is inserted with the convex shaft 307 arranged on one side of the moving iron core 302, thereby realizing the connection with the moving iron core 302. At this time, since the diameter of the limiting plate 305 is larger than that of the first through cavity 311, and the diameter of the moving iron core 302 is larger than that of the second through cavity 304, the moving iron core 302 will not fall out of the sleeve 301. The installed sleeve 301 is placed inside the circuit breaker body 1. At the same time, the set first connecting frame 314 and the second connecting frame 318 can be disassembled. Then, the outer wall of the sleeve 301 is sleeved on the inner wall of the first receiving groove 317 to achieve a clamping fit. At the same time, the second receiving groove 319 on the other end is clamped and fitted with the outside of the collar 312. After placing its two bottom plates 315 inside the circuit breaker body 1, use tools to tighten the installation bolts 316 to complete the installation. When it needs to be disassembled, the opposite can also be achieved. When installing the circuit breaker body 1, the adjusting bolt 204 can be loosened, and the outer mounting plate 208 is moved outward along the mounting groove 205 to a specified length. Then, the sliding plate 206 on the connecting plate 201 is fastened. The fastening installation process is realized by using the opened limiting hole 203 and the adjusting bolt 204. At the same time, with the cooperation of the pin hole 209 and the clamping block 210, it is convenient to fasten and install the two mounting plates 208, and disassembly can also be achieved.

[0042] The present invention covers any alternatives, modifications, equivalent methods, and solutions made within the spirit and scope of the present invention. To enable the public to have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention. However, those skilled in the art can fully understand the present invention even without the description of these details. Additionally, well-known methods, processes, procedures, components, and circuits are not described in detail to avoid unnecessary confusion to the essence of the present invention.

[0043] Those of ordinary skill in the art can understand that all or part of the steps in implementing the methods of the above embodiments can be completed by instructing relevant hardware through a program, and this program can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disks, optical discs, etc.

[0044] The above description is only a preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A circuit breaker with a simplified release, comprising a circuit breaker body (1), characterized in that: The circuit breaker body (1) includes a release installation mechanism (3) with a detachable connection, and two side walls of the circuit breaker body (1) are provided with limit mechanisms (2); A release installation mechanism (3) comprises a sleeve (301), a coil (313), a first through cavity (311), a static iron core (303), a moving iron core (302), a second through cavity (304), a push rod (306), a limit plate (305) and a spring (309), wherein the outer surface of the sleeve (301) is sleeved with a coil (313), the inner cavity of the sleeve (301) is axially provided with a first through cavity (311), the static iron core (303) is arranged in the sleeve (301) and is engaged with the inner wall of the first through cavity (311), and the static iron core (303) is engaged with the inner wall of the first through cavity (311). A second through cavity (304) is axially opened inside the iron core (303), the moving iron core (302) and the first through cavity (311) are used in conjunction with each other in a clearance, a push rod (306) is embedded in the inner cavity of the static iron core (303), one end of the push rod (306) is in contact with the side wall of the moving iron core (302), the other end of the push rod (306) passes through the second through cavity (304) and is detachably mounted with a limit plate (305), and a spring (309) is also provided between the axial outer wall of the moving iron core (302) and the static iron core (303).

2. A circuit breaker with a simplified release according to claim 1, characterized in that: The release mounting mechanism (3) further comprises a first connecting frame (314), a second connecting frame (318), a first accommodating groove (317) and a second accommodating groove (319); the first connecting frame (314) and the second connecting frame (318) are arranged in the circuit breaker body (1); the first connecting frame (314) and the second connecting frame (318) both comprise a bottom plate (315) and mounting bolts (316); the four corners of the upper end surface of the bottom plate (315) are connected with mounting bolts (316); the bottoms of the first connecting frame (314) and the second connecting frame (318) are fixedly connected to the bottom plate (315); the first connecting frame (314) is provided with a first accommodating groove (317); the second connecting frame (318) is provided with a second accommodating groove (319).

3. The circuit breaker with a simplified release according to claim 1, characterized in that: The moving iron core (302) is provided with a convex shaft (307), and one end of the push rod (306) is provided with a groove (308) that is snap-fitted with the convex shaft (307).

4. The circuit breaker with a simplified release according to claim 1, characterized in that: The limiting mechanism (2) comprises a sliding member (22) and a fastener (21); the two side walls of the circuit breaker body (1) are fixedly connected to the fastener (21); the sliding member (22) is slidably arranged inside the fastener (21); the fastener (21) comprises a connecting plate (201), a mounting groove (205), a sliding groove (202), a sliding plate (206), a sliding block (207), a mounting plate (208) and a pin hole (209); the two side walls of the circuit breaker body (1) are fixedly connected to the connecting plate (201) by bolts; The inner cavity of the connecting plate (201) is provided with a mounting groove (205), and the two side walls are provided with sliding grooves (202), the mounting groove (205) is connected to the sliding groove (202), a slide plate (206) is slidably connected inside the connecting plate (201), the outer wall of the slide plate (206) is fixedly connected with a mounting plate (208), the mounting plate (208) is provided with a pin hole (209), and the two side walls of the slide plate (206) are fixedly connected with sliders (207), and the sliders (207) are in sliding contact with the sliding grooves (202).

5. A circuit breaker with a simplified release according to claim 4, characterized in that: The fastener (21) comprises a limiting hole (203) and an adjusting bolt (204); a plurality of evenly distributed limiting holes (203) are provided on both sides of the outer wall of the connecting plate (201); an adjusting bolt (204) is provided on the upper end surface of the connecting plate (201); the adjusting bolt (204) is slidably arranged in the limiting hole (203) and penetrates and extends to the inner wall of the sliding block (207).

6. A circuit breaker with a simplified release according to claim 4, characterized in that: A clamping block (210) is fixedly connected to the bottom of the mounting plate (208), and an inclined surface is provided on the clamping block (210), and the inclination angle of the inclined surface is 30-70 degrees.

7. The circuit breaker with a simplified release according to claim 2, characterized in that: The diameter of the first receiving groove (317) is greater than the diameter of the second receiving groove (319), and the first receiving groove (317) is tightly fitted with the outer wall of the sleeve (301). A ring (312) is provided at the connection between one end of the static iron core (303) and the outer wall of the sleeve (301), and the second receiving groove (319) is tightly fitted with the outer wall of the ring (312).

8. The circuit breaker with a simplified release according to claim 1, characterized in that: A convex ring (310) is provided on the inner wall of the second through cavity (304), and one end of the spring (309) is arranged in the second through cavity (304) and the bottom thereof is pressed against the convex ring (310).

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