A switch disconnector insulating porcelain bushing

Abstract

The application belongs to the technical field of insulating porcelain sleeves, and particularly relates to a switch circuit breaker insulating porcelain sleeve; the switch circuit breaker insulating porcelain sleeve comprises a middle guide cylinder, a porcelain skirt edge, an outer supporting structure and an inner supporting structure; outer walls of the middle guide cylinder are uniformly provided with the outer supporting structure and the porcelain skirt edge corresponding to the outer supporting structure from top to bottom, the porcelain skirt edge is sleeved on the outer wall of the middle guide cylinder and is inserted and arranged on the outer supporting structure; the inner part of the middle guide cylinder is provided with the inner supporting structure, the inner supporting structure is used for positioning the outer supporting structure by penetrating from the inner part of the middle guide cylinder to the outer part; the application adopts a three-stage sealing structure: the first-stage sealing is arranged at the inner connecting part of the outer supporting structure, radial dynamic sealing is realized; the second-stage sealing is arranged at the connecting interface of the porcelain skirt edge and the middle guide cylinder and the outer supporting structure, interface static sealing is realized; the third-stage sealing is arranged at the connecting part of the end part of the middle guide cylinder and the inner supporting structure, end surface axial sealing is realized.

Description

Technical Field

[0001] This invention belongs to the field of insulating porcelain bushing technology, and particularly relates to an insulating porcelain bushing for a switch circuit breaker. Background Technology

[0002] Insulating porcelain bushings are crucial external insulation components in circuit breakers. Their core function is to isolate the high-potential conductive parts inside the circuit breaker (such as moving contacts, stationary contacts, and arc-extinguishing chambers) from the grounded equipment casing (such as circuit breaker supports and tanks), forming sufficient insulation strength to prevent high-voltage breakdown to ground and ensure equipment and personnel safety. At the same time, as an exposed part of the equipment, it must be able to withstand the environmental challenges of nature, such as rain, snow, fog, and pollution, and maintain stable insulation performance under various harsh weather conditions.

[0003] Currently, most insulating porcelain sleeves are manufactured as a single piece. They are formed by sintering clay blanks, then grinding and glazing them before assembly and testing. However, the umbrella-shaped porcelain skirt on the outer wall of these single-piece insulating porcelain sleeves is prone to cracking or developing micro-cracks and other stress damage during transportation, which seriously affects their insulation performance during subsequent use. The reason why current insulating porcelain sleeves mostly adopt a single-piece structure instead of a separate assembly is that the sealing performance of the assembly position of the currently assembled insulating porcelain sleeves is difficult to guarantee, making it difficult to maintain stable insulation performance in the external environment.

[0004] Therefore, in order to ensure the sealing performance of the insulating porcelain bushing while reducing the probability of stress damage during transportation and improving the convenience of transportation, this invention provides an insulating porcelain bushing for a switch circuit breaker. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an insulating porcelain bushing for a circuit breaker, which solves the problems mentioned in the background section.

[0006] To achieve the above objectives, the present application provides the following technical solution: The present invention provides an insulating porcelain bushing for a circuit breaker, comprising a central guide tube, a porcelain skirt, an outer support structure, and an inner support structure; the outer wall of the central guide tube is uniformly provided with an outer support structure and porcelain skirts corresponding to the outer support structure from top to bottom, and the porcelain skirts are sleeved on the outer wall of the central guide tube and inserted into the outer support structure.

[0007] The middle guide tube has an internal support structure, which is used to position the external support structure from the inside of the middle guide tube to its outside.

[0008] The insulating porcelain sleeve adopts a two-stage fixing structure: the first stage is to fix the porcelain skirt to the outer wall of the middle guide tube through the outer support structure in an external radial direction; the second stage is to fix it through the inner support structure through the middle guide tube and lock the outer support structure in an internal axial direction.

[0009] The insulating porcelain sleeve adopts a three-level sealing structure: the first level seal is set at the internal connection of the outer support structure to achieve radial dynamic sealing; the second level seal is set at the connection interface between the porcelain skirt and the middle guide cylinder and the outer support structure to achieve interface static sealing; the third level seal is set at the connection between the end of the middle guide cylinder and the inner support structure to achieve end face axial sealing.

[0010] According to an advantageous embodiment, the central guide tube is made of ceramic material, and both the upper and lower ends of the central guide tube are stepped. The central guide tube is provided with a plurality of through holes that penetrate its center, and the plurality of through holes are evenly arranged along the axial direction of the central guide tube.

[0011] According to an advantageous embodiment, the outer support structure includes a magnetic ring sleeve fitted on the outer wall of the central guide cylinder, the upper end of which is provided with an upper support section for threaded connection with the ceramic skirt edge; the outer support structure also includes a limiting ring fitted on the outer wall of the central guide cylinder and located below the magnetic ring sleeve, the middle part of which is provided with a middle locking section for insertion and locking with the inner support structure; the lower end of the magnetic ring sleeve is provided with a lower connecting section for fixing with the limiting ring; the limiting ring and the lower connecting section at the lower end of the magnetic ring sleeve are threadedly engaged, and a sealing rubber ring is also provided at the engagement point of the two.

[0012] According to an advantageous embodiment, the upper side of the limiting ring is configured as an external thread section, which is composed of several evenly arranged arc segments. The inner side of the external thread section of the limiting ring is provided with a rubber sleeve with a right-angled trapezoidal cross section. The limiting ring is threadedly connected to the lower connecting section of the magnetic ring sleeve, and each arc segment is close to the axis of the limiting ring. The position of the limiting ring is fixed and the insulation is achieved by deforming and squeezing the rubber sleeve through the arc segments.

[0013] According to an advantageous embodiment, the internal support structure includes a hollow guide rod disposed inside the central guide cylinder. The two ends of the hollow guide rod are fixed inside the central guide cylinder by flanges threaded to them. Rubber gaskets are provided at the upper and lower stepped ends of the flanges and the central guide cylinder.

[0014] The hollow guide rod has several limiting grooves evenly arranged along its axial direction, each corresponding to and penetrating the through holes on the central guide cylinder. These limiting grooves penetrate the interior of the hollow guide rod. A support sleeve is provided on the outer wall of the hollow guide rod below each limiting groove. A set of lugs is provided on the support sleeve at the position corresponding to the limiting groove. A limiting rod is rotatably mounted within each lug via a torsion spring. A locking rod is slidably fitted onto the outer wall of the limiting rod. A limiting spring is installed in the sliding groove between the locking rod and the limiting rod. A strip-shaped pressure plate is also installed through the interior of the limiting groove. The lower end of the strip-shaped pressure plate mates with one end of the locking rod. A through groove is provided in the middle of the strip-shaped pressure plate. When the strip-shaped pressure plate presses down on the locking rod, the limiting spring is compressed, and the other end of the locking rod gradually penetrates the through hole on the central guide cylinder and locks in the middle locking section of the magnetic ring sleeve.

[0015] According to an advantageous embodiment, the inner support structure further includes two threaded fixing rods disposed outside the hollow guide rod. A plurality of evenly arranged pressing members are sleeved between the two threaded fixing rods. The pressing members are fixed by nuts disposed on the outer wall of the threaded fixing rods. The spacing between two adjacent pressing members is the same as the spacing between adjacent ceramic skirts. An adjusting nut is disposed on the upper outer wall of the hollow guide rod for driving all pressing members to move downward together.

[0016] According to an advantageous embodiment, the sealing ring and the rubber sleeve together form the first-level seal.

[0017] According to an advantageous embodiment, a rubber sealing ring is provided at the connection between the ceramic skirt and the magnetic ring sleeve, and between the ceramic skirt and the outer wall of the central guide cylinder, to form the second-level seal.

[0018] According to an advantageous embodiment, a rubber gasket disposed between the flange and the stepped end face of the central guide tube forms the third-level seal.

[0019] Compared with the prior art, the insulating porcelain bushing of the circuit breaker provided by the present invention has the following beneficial effects: 1. The present invention decomposes the traditional porcelain bushing into a central guide tube, a detachable porcelain skirt and a matching support structure, realizing modular transportation, which greatly reduces the risk of damage caused by vibration during transportation. At the same time, the split design reduces the weight of a single piece and improves the convenience of handling and storage.

[0020] 2. This invention addresses the sealing difficulties in split-assembly. It employs a first-level radial seal at the connection between the limiting ring and the magnetic ring sleeve, achieved through the compression of a sealing rubber ring and a rubber sleeve. Simultaneously, rubber sealing rings are placed between the ceramic skirt and the magnetic ring sleeve, and between the outer wall of the central guide cylinder, blocking the path of seepage along the through hole, thus completing a second-level seal. Furthermore, flanges and rubber gaskets at both ends of the hollow guide rod press against the stepped end face of the central guide cylinder, achieving a third-level seal and ensuring internal airtightness. Through the synergistic effect of these multi-level seals, the ceramic sleeve maintains high insulation strength even in harsh environments such as rain, snow, and dirt.

[0021] 3. This invention achieves two-stage fixation of the ceramic skirt through the linkage design of the outer support structure and the inner support structure. In specific fixing, the ceramic skirt is first pressed by the threaded engagement of the magnetic ring sleeve and the limiting ring to provide basic support, forming the first-stage external radial fixation; then, the inner support structure is inserted into the locking section of the magnetic ring sleeve through the through hole of the locking rod, applying radial locking force from the inside out to avoid displacement caused by thermal expansion and contraction or vibration, forming the second-stage internal axial locking fixation. The dual fixation not only improves the anti-displacement ability of the ceramic skirt, but also simplifies the assembly process through integrated operation (rotating the adjusting nut can lock all ceramic skirts simultaneously), ensuring assembly efficiency and consistency. Attached Figure Description

[0022] Figure 1 This is a three-dimensional structural diagram of the present invention from the main view position.

[0023] Figure 2 This is a cross-sectional view of the internal structure of the present invention when the internal support structure is just inserted into the middle guide tube.

[0024] Figure 3 For the present invention Figure 2 Cross-sectional view of the internal structure after the adjusting nut is turned into contact with the top of the pressing part.

[0025] Figure 4 For the present invention Figure 3 A cross-sectional view of the structure after the adjusting nut is turned and locked between the locking rod and the magnetic ring sleeve.

[0026] Figure 5 For the present invention Figure 2 A magnified view of section A in the image.

[0027] Figure 6 This is a perspective view of the support sleeve and the limiting rod of the present invention.

[0028] Figure 7 This is a perspective view of the strip pressure plate of the present invention.

[0029] Figure 8 This is a cross-sectional view of the present invention showing multiple pressing components fixed to a threaded fixing rod by nuts.

[0030] Figure 9 This is a three-dimensional structural diagram of the limiting ring of the present invention.

[0031] The attached diagram shows the following labels: 1. Middle guide tube; 2. Ceramic skirt; 3. Outer support structure; 4. Inner support structure; 5. Conductive rod; 11. Through hole; 31. Magnetic ring sleeve; 311. Upper support section; 312. Middle locking section; 313. Lower connecting section; 32. Limiting ring; 321. Arc-shaped section; 33. Sealing ring; 34. Rubber sleeve; 41. Hollow guide rod; 42. Support sleeve; 43. Ear seat; 44. Limiting rod; 45. Locking rod; 46. Limiting spring; 47. Strip pressure plate; 471. Through hole; 48. Threaded fixing rod; 49. Pressing element; 410. Adjusting nut; 411. Limiting groove; 412. Flange; 413. Rubber gasket. Detailed Implementation

[0032] The following is in conjunction with the appendix Figure 1 - Appendix Figure 9 This application will now be described in further detail.

[0033] Please refer to the following: Figure 1 and Figure 3 An insulating porcelain bushing for a circuit breaker includes a central guide cylinder 1, porcelain skirts 2, an outer support structure 3, and an inner support structure 4. The outer wall of the central guide cylinder 1 is evenly provided with outer support structures 3 and porcelain skirts 2 corresponding to the outer support structures 3 from top to bottom. The porcelain skirts 2 are sleeved on the outer wall of the central guide cylinder 1 and inserted into the outer support structures 3. An inner support structure 4 is provided inside the central guide cylinder 1. The inner support structure 4 is used to position the outer support structures 3 by penetrating from the inside of the central guide cylinder 1 to the outside. A conductive rod 5 is inserted through the inner support structure 4.

[0034] During assembly, several porcelain skirts 2 are first fixed to the outer wall of the central guide tube 1 one by one using the outer support structure 3. It should be noted that the distance between two adjacent porcelain skirts 2 is set according to the installation standard. Then, the inner support structure 4 is fixed inside the central guide tube 1. The porcelain skirts 2 fixed externally are then positioned and fixed by operating the inner support structure 4. The stability of the porcelain skirts 2 after fixing is ensured by the double fixing method. At the same time, the sealing between the porcelain skirts 2 and the central guide tube 1, between the central guide tube 1 and the outer support structure 3, and between the inner support structure 4 and the central guide tube 1 are maintained during the internal and external fixing. Finally, a conductive rod 5 is installed through the inner support structure 4. The upper end of the conductive rod 5 is connected to the stationary contact of the circuit breaker arc-extinguishing chamber, and the lower end of the conductive rod 5 is connected to the moving contact of the circuit breaker arc-extinguishing chamber.

[0035] See Figure 2 and Figure 3The central guide tube 1 is made of ceramic material. Both the upper and lower ends of the central guide tube 1 are stepped. The central guide tube 1 is provided with several through holes 11 that penetrate its center. The several through holes 11 are evenly arranged along the axial direction of the central guide tube 1. It should be noted that the spacing between two adjacent through holes 11 is set according to the production standard corresponding to the specific model.

[0036] See Figure 2 and Figure 3 and Figure 5 The outer support structure 3 includes a magnetic ring sleeve 31 sleeved on the outer wall of the middle guide cylinder 1. The upper end of the magnetic ring sleeve 31 is provided with an upper support section 311 for threaded connection with the ceramic skirt 2. The middle part of the magnetic ring sleeve 31 is provided with a middle locking section 312 for insertion and locking with the inner support structure 4. The outer support structure 3 also includes a limiting ring 32 sleeved on the outer wall of the middle guide cylinder 1 and located below the magnetic ring sleeve 31. The lower end of the magnetic ring sleeve 31 is provided with a lower connecting section 313 for fixing with the limiting ring 32. The limiting ring 32 and the lower connecting section 313 at the lower end of the magnetic ring sleeve 31 are threadedly engaged, and a sealing rubber ring 33 is also provided at the engagement point of the two.

[0037] See Figure 5 and Figure 9 The upper side of the limiting ring 32 is provided with an external thread section, which is composed of several evenly arranged arc segments 321. The inner side of the external thread section of the limiting ring 32 is provided with a rubber sleeve 34 with a right trapezoidal cross section. The limiting ring 32 is threadedly connected to the lower connecting section 313 of the magnetic ring sleeve 31, and each arc segment 321 is close to the axis of the limiting ring 32. The position of the limiting ring 32 is fixed and the insulation is achieved by deforming and squeezing the rubber sleeve 34 through the arc segment 321.

[0038] Before installing the ceramic skirt 2, a rubber sleeve 34 needs to be fitted inside the limiting ring 32, and a sealing ring 33 needs to be fitted outside it. Specifically, when installing the ceramic skirt 2, the limiting ring 32, the magnetic ring sleeve 31, and the ceramic skirt 2 are fitted onto the outer wall of the middle guide cylinder 1 in sequence. Then, the middle locking section 312 of the magnetic ring sleeve 31 is aligned with the through hole 11 at the installation position. Subsequently, the limiting ring 32 is screwed to cooperate with the magnetic ring sleeve 31, and the position of the magnetic ring sleeve 31 is fixed by the limiting ring 32. During the tightening of the limiting ring 32, the sealing ring 33 and the rubber sleeve 34 work together to seal the connection position. After completion, the ceramic skirt 2 is screwed onto the upper support section 311 of the magnetic ring sleeve 31. It should be noted that in order to ensure the sealing effect after the ceramic skirt 2 is fixed on the outer wall of the middle guide cylinder 1, please refer to the appendix. Figure 2Rubber sealing rings are installed at the connection between the ceramic skirt 2 and the magnetic ring sleeve 31, and between the ceramic skirt 2 and the outer wall of the central guide cylinder 1. The rubber sealing rings further prevent rain, snow, fog, dirt and other external environmental elements from entering the interior of the central guide cylinder 1 through the through hole 11, thus avoiding poor sealing performance and affecting insulation performance. Multiple sealing treatments are applied to the upper and lower sides of the connection between the individual ceramic skirt 2 and the central guide cylinder 1, effectively preventing impurities from entering the interior of the central guide cylinder 1 through the through hole 11, thereby effectively ensuring its insulation performance during use. At the same time, the ceramic skirt 2 is designed as a detachable structure, which facilitates its transportation and assembly, avoiding the problems of large-scale breakage during transportation caused by the existing integrated structure.

[0039] To further improve the stability of the magnetic ring sleeve 31 on the central guide cylinder 1, thereby ensuring the fixing effect of the ceramic skirt 2 and preventing relative displacement of the ceramic skirt 2 on the central guide cylinder 1 due to external factors such as thermal expansion and contraction during later use after assembly, the inner support structure 4 further supports and fixes all the ceramic skirts 2 assembled on the central guide cylinder 1 from the inside out; see reference. Figure 4 and Figure 5 The inner support structure 4 includes a hollow guide rod 41 disposed inside the middle guide cylinder 1. The two ends of the hollow guide rod 41 are fixed inside the middle guide cylinder 1 by flanges 412 that are threadedly connected to it. Rubber gaskets 413 are provided at the upper and lower steps of the flanges 412 and the middle guide cylinder 1.

[0040] See Figure 5 , Figure 6 and Figure 7 The outer wall of the hollow guide rod 41 is uniformly provided with a plurality of limiting grooves 411 that correspond one-to-one with and pass through the through holes 11 on the central guide cylinder 1. The limiting grooves 411 penetrate the interior of the hollow guide rod 41. A support sleeve 42 is provided on the outer wall of the hollow guide rod 41 below each limiting groove 411. A set of lugs 43 is provided on the support sleeve 42 at the position corresponding to the limiting groove 411. A limiting rod 44 is rotatably provided in each lug 43 through a torsion spring. The outer wall of the limiting rod 44 is fitted with a sliding fit. The locking rod 45 has a sliding groove between it and the limiting rod 44, and a limiting spring 46 is provided in the groove. A strip-shaped pressure plate 47 is also provided inside the limiting groove 411. The lower end face of the strip-shaped pressure plate 47 cooperates with one end of the locking rod 45. The middle part of the strip-shaped pressure plate 47 is provided with a through hole 471 for the conductive rod 5 to pass through. When the strip-shaped pressure plate 47 presses down on the locking rod 45, the limiting spring 46 is compressed. The other end of the locking rod 45 gradually passes through the through hole 11 on the middle guide cylinder 1 and is locked in the middle locking section 312 of the magnetic ring sleeve 31.

[0041] Continue reading Figure 5 and Figure 8 The inner support structure 4 also includes two threaded fixing rods 48 disposed outside the hollow guide rod 41. Several evenly arranged pressing parts 49 are sleeved between the two threaded fixing rods 48. The pressing parts 49 are fixed by nuts disposed on the outer wall of the threaded fixing rods 48. The distance between two adjacent pressing parts 49 is the same as the distance between adjacent ceramic skirts 2. The upper outer wall of the hollow guide rod 41 is threaded with an adjusting nut 410 for driving all pressing parts 49 to move downward together.

[0042] When assembling the internal support structure 4, please refer to... Figures 2-4 First, assemble several pressing parts 49 on the threaded fixing rod 48, and then put them on the outside of the hollow guide rod 41. Next, place strip pressure plates 47 inside each corresponding limiting groove 411, and then thread adjusting nuts 410 on the upper outer wall of the hollow guide rod 41.

[0043] Next, after completing the above assembly, insert the entire assembly into the interior of the central guide cylinder 1. It should be noted that the interior of the central guide cylinder 1 has a sliding groove for limiting the pressing member 49. Then, tighten the adjusting nut 410 to press down the upper end of the threaded fixing rod 48. This causes all the pressing members 49 to move down along the sliding groove together, pressing down the corresponding locking rod 45. The locking rod 45 slides under the limit of the limiting rod 44 and twists at a certain angle until the locking rod 45 is inserted into the corresponding through hole 11 and passes through, then locks into the middle locking section 312 in the middle of the magnetic ring sleeve 31; thus completing the further fixation of the position of the magnetic ring sleeve 31.

[0044] Finally, after the above locking is completed, the hollow guide rod 41 is fixed to both ends of the middle guide cylinder 1 by the flange 412, and the step is sealed by the rubber gasket 413.

[0045] The single operation of the inner support structure 4 enables all magnetic ring sleeves 31 to be fixed synchronously and integrally, simplifying the assembly steps and ensuring the sealing of the internal structure after assembly.

[0046] This invention achieves primary sealing and insulation through a rubber sleeve 34 fitted inside the limiting ring 32 and a sealing ring 33 fitted outside. Secondary sealing and insulation are achieved by setting rubber sealing rings at the connection between the ceramic skirt 2 and the magnetic ring sleeve 31, and between the ceramic skirt 2 and the outer wall of the central guide cylinder 1. Tertiary sealing is achieved by using flanges 412 and rubber gaskets 413 to compress the upper and lower ends of the central guide cylinder 1. These multi-stage sealing techniques ensure the sealing and insulation performance of the assembled insulating ceramic sleeve. Furthermore, the magnetic ring sleeve 31 and the limiting ring 32 work together to achieve primary external radial fixation of the ceramic skirt 2, and the inner support structure 4 further axially locks the magnetic ring sleeve 31, thus achieving secondary fixing of the ceramic skirt 2's installation position. These two stages of fixing ensure the stability of the ceramic skirt 2 after fixation, preventing relative movement on the outer wall of the central guide cylinder 1 and ensuring the stability of the assembled insulating ceramic sleeve.

[0047] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0048] Furthermore, the terms "first," "second," "number one," and "number two" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," "number one," or "number two" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A porcelain insulating bushing for a circuit breaker, comprising a central guide tube, porcelain skirts, an outer support structure, and an inner support structure; characterized in that: The outer wall of the middle guide tube is evenly provided with an outer support structure and a ceramic skirt corresponding to the outer support structure from top to bottom. The ceramic skirt is sleeved on the outer wall of the middle guide tube and inserted into the outer support structure. The middle guide tube is provided with an internal support structure, which is used to position the external support structure from the inside of the middle guide tube to its outside. The insulating porcelain sleeve adopts a two-stage fixing structure: the first stage is to fix the porcelain skirt to the outer wall of the middle guide cylinder through the outer support structure in an external radial direction; the second stage is to fix it through the inner support structure through the middle guide cylinder and lock the outer support structure in an internal axial direction. The insulating porcelain sleeve adopts a three-level sealing structure: the first level of sealing is set at the internal connection of the outer support structure to achieve radial dynamic sealing; the second level of sealing is set at the connection interface between the porcelain skirt and the middle guide cylinder and the outer support structure to achieve interface static sealing; the third level of sealing is set at the connection between the end of the middle guide cylinder and the inner support structure to achieve end face axial sealing. The outer support structure includes a magnetic ring sleeve fitted on the outer wall of the central guide cylinder. The upper end of the magnetic ring sleeve is provided with an upper support section for threaded connection with the ceramic skirt edge. The middle part of the magnetic ring sleeve is provided with a middle locking section for insertion and locking with the inner support structure. The outer support structure also includes a limiting ring fitted on the outer wall of the central guide cylinder and located below the magnetic ring sleeve. The lower end of the magnetic ring sleeve is provided with a lower connecting section for fixing with the limiting ring. The limiting ring and the lower connecting section at the lower end of the magnetic ring sleeve are threadedly engaged, and a sealing rubber ring is provided at the engagement point between the two. The internal support structure includes a hollow guide rod disposed inside the central guide cylinder. The two ends of the hollow guide rod are fixed inside the central guide cylinder by flanges that are threadedly connected to it. Rubber gaskets are provided at the upper and lower steps of the flanges and the central guide cylinder. The hollow guide rod has several limiting grooves evenly arranged along its axial direction, each corresponding to and communicating with the through holes on the central guide cylinder. The limiting grooves penetrate the interior of the hollow guide rod. A support sleeve is provided on the outer wall of the hollow guide rod below each limiting groove. A set of lugs is provided on the support sleeve at the position corresponding to the limiting groove. A limiting rod is rotatably installed in each lug through a torsion spring. A locking rod is slidably fitted on the outer wall of the limiting rod. A limiting spring is provided in the sliding groove between the locking rod and the limiting rod. A strip-shaped pressure plate is also installed through the interior of the limiting groove. The lower end face of the strip-shaped pressure plate mates with one end of the locking rod. A through hole is provided in the middle of the strip-shaped pressure plate. When the strip-shaped pressure plate presses down on the locking rod, the limiting spring is compressed. The other end of the locking rod gradually penetrates the through hole on the central guide cylinder and locks in the middle locking section of the magnetic ring sleeve.

2. The insulating porcelain bushing of a switch circuit breaker according to claim 1, characterized in that, The central guide tube is made of ceramic material. Both the upper and lower ends of the central guide tube are stepped. The central guide tube has several through holes that penetrate its center. The several through holes are evenly arranged along the axial direction of the central guide tube.

3. The insulating porcelain bushing of a switch circuit breaker according to claim 1, characterized in that, The upper side of the limiting ring is configured with an external thread section, which is composed of several evenly arranged arc segments. The inner side of the external thread section of the limiting ring is provided with a rubber sleeve with a right-angled trapezoidal cross section. The limiting ring is threadedly connected to the lower connecting section of the magnetic ring sleeve, and each arc segment is close to the axis of the limiting ring. The position of the limiting ring is fixed and the insulation is achieved by deforming and squeezing the rubber sleeve through the arc segments.

4. The insulating porcelain bushing of a circuit breaker according to claim 3, characterized in that, The internal support structure also includes two threaded fixing rods set outside the hollow guide rod. Several evenly arranged pressing parts are sleeved between the two threaded fixing rods. The pressing parts are fixed by nuts set on the outer wall of the threaded fixing rods. The distance between two adjacent pressing parts is the same as the distance between adjacent ceramic skirts. The upper outer wall of the hollow guide rod is provided with an adjusting nut for driving all pressing parts to move down together.

5. The insulating porcelain bushing of a switch circuit breaker according to claim 2, characterized in that, The sealing ring and the rubber sleeve together form the first-level seal.

6. The insulating porcelain bushing of a switch circuit breaker according to claim 1, characterized in that, A rubber sealing ring is provided at the connection between the ceramic skirt and the magnetic ring sleeve, and between the ceramic skirt and the outer wall of the central guide cylinder, forming the second-level seal.

7. The insulating porcelain bushing of a switch circuit breaker according to claim 1, characterized in that, The rubber gasket placed between the flange and the stepped end face of the central guide tube forms the third-level seal.

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