Composite sleeve

Abstract

The invention discloses a composite bushing, which comprises an insulating tube, an umbrella cover wrapping the periphery of the insulating tube, and an upper fitting and a lower fitting which are respectively sleeved at two ends of the insulating tube, the upper fitting comprises a bolt, a connecting piece and a stranded wire, the connecting piece comprises a connecting part and a first connecting cylinder which are connected with each other, and the connecting part is in sealed connection with the bolt; the first connecting cylinder is in sealed connection with the insulating tube, the lower fitting comprises a second connecting cylinder and a flange, the flange extends outwards from the outer wall of one end of the second connecting cylinder in the radial direction of the second connecting cylinder, and the flange is of a disc-shaped structure and is of a non-planar structure. The composite sleeve has the advantages of being light in weight and high in structural strength; and meanwhile, the unevenness of the mounting end face of the capacitor can be allowed to a certain extent, the accurate fitting with the connecting end face of the capacitor is realized, and the problems of inclined mounting or sealing failure of the composite sleeve caused by the deformation of the connecting end face of the capacitor are avoided.

Description

Technical Field

[0001] This application relates to the field of power equipment, and in particular to a composite bushing. Background Technology

[0002] Currently, most capacitor bushings in the power industry are made of ceramic. The material and structure of ceramic bushings make them relatively heavy, and ceramic materials have poor impact and seismic resistance, making them prone to cracking or exploding during earthquakes or other impacts. Furthermore, the ceramic surface lacks hydrophobicity, making it susceptible to water and ice bridges under harsh conditions such as heavy rain or ice melt, potentially leading to flashover accidents. Due to the poor hydrophobicity of ceramics, it is often necessary to periodically apply RTV (Regenerative Thermal Varnish) to the surface of the ceramic bushings to improve hydrophobicity, resulting in high maintenance costs during use.

[0003] In addition, the surfaces of the hardware connecting the capacitor bushing and the capacitor are mostly flat. To avoid the bushing tilting during installation, the flatness of the capacitor is required to be high. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the main objective of this application is to provide a composite bushing that is lightweight and has high structural strength, and can avoid problems such as tilting during installation or sealing failure caused by deformation of the capacitor connection end face.

[0005] To solve the above-mentioned technical problems, the technical solution adopted in this application is: a composite sleeve, including an insulating tube, an umbrella sleeve covering the outer periphery of the insulating tube, and upper and lower fittings respectively fitted at both ends of the insulating tube. The insulating tube is a hollow tube made of composite material. The upper fitting is fixedly connected to the first end of the insulating tube, and the lower fitting is fixedly connected to the second end of the insulating tube. The upper fitting includes a bolt, a connector, and a stranded wire. The connector includes a connecting part and a first connecting cylinder that are connected to each other. The connecting part is sealed to the bolt, and the first connecting cylinder is sealed to the insulating tube. One end of the stranded wire is fixedly connected to the bolt, and the other end passes through the hollow inner cavity of the insulating tube and extends out of the second end of the insulating tube. The lower fitting includes a second connecting cylinder and a flange. The flange extends outward from the outer wall of one end of the second connecting cylinder along the radial direction of the second connecting cylinder. The flange has a disc-shaped structure and is a non-planar structure.

[0006] The insulating tube has an annular groove on its outer periphery at the first end, forming a sealed cavity between the insulating tube and the first connecting cylinder to accommodate the sealant.

[0007] Both the connecting part and the first connecting cylinder are hollow cylindrical structures. The diameter of the connecting part is smaller than the diameter of the first connecting cylinder. The connecting part and the first connecting cylinder are connected by an end cap and are integrally formed. The end cap seals one side opening of the first connecting cylinder. The end cap has a through hole in the center. The connecting part is located on the through hole and on the end face of the end cap away from the first connecting cylinder.

[0008] The inner wall of the first connecting cylinder is provided with a sealing groove, which is located on the mating surface formed after the connector and the insulating tube are assembled.

[0009] The bolt has a connecting hole at one end near the connector, and the stranded wire extends into the connecting hole and is fixed by crimping.

[0010] Among them, the disc surface of the flange away from the second connecting cylinder includes a first support surface, a second support surface and a third support surface in sequence from the inside to the outside along its radial direction. The first support surface, the second support surface and the third support surface are located in different planes and are parallel to each other.

[0011] The distance between the plane containing the second support surface and the plane containing the top of the second connecting cylinder is less than the distance between the plane containing the first support surface and the plane containing the top of the second connecting cylinder; the distance between the plane containing the third support surface and the plane containing the top of the second connecting cylinder is greater than the distance between the plane containing the first support surface and the plane containing the top of the second connecting cylinder.

[0012] The distance between the plane containing the second support surface and the plane containing the first support surface is 0.5 mm, and the distance between the plane containing the third support surface and the plane containing the first support surface is 0.5 mm.

[0013] The flange includes a first transition surface, which is an inclined surface. The first transition surface extends upward from the first support surface and connects to the second support surface.

[0014] The flange includes a second transition surface, which is a vertical surface. The second transition surface extends downward from the second support surface along the axial direction of the flange and connects to the third support surface.

[0015] Among them, the umbrella sleeve covers the transition area between the insulating tube and the upper and lower fittings, and the covering length at both ends of the umbrella sleeve extends 20-40mm along the axial direction of the insulating tube to the upper and lower fittings respectively.

[0016] The beneficial effects of this application are: the composite sleeve of this application has the advantages of light weight and high structural strength, and has excellent high temperature resistance, oil resistance, corrosion resistance, aging resistance and impact resistance.

[0017] Meanwhile, compared to rigid conductive rods, the stranded wires of the fittings in this application can be bent and adjusted more easily during installation. When faced with impact and vibration, they can avoid stress concentration and fatigue damage through deformation, thus providing higher reliability and durability.

[0018] Furthermore, the flange of the fitting in this application is set to be non-planar, which can tolerate the unevenness of the capacitor mounting end face to a certain extent, achieve precise fit with the capacitor connection end face, and avoid problems such as tilting of the composite sleeve installation or sealing failure caused by deformation of the capacitor connection end face. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0020] Figure 1 This is a three-dimensional structural schematic diagram of the composite sleeve 100 in one embodiment of this application;

[0021] Figure 2 This is a cross-sectional view of the composite sleeve 100 in one embodiment of this application;

[0022] Figure 3 yes Figure 2 Enlarged view of point A in the middle;

[0023] Figure 4 This is a three-dimensional structural diagram of the upper hardware 400 in one embodiment of this application;

[0024] Figure 5 This is a three-dimensional structural schematic diagram of the lower hardware 500 in one embodiment of this application;

[0025] Figure 6 This is a cross-sectional view of the lower fitting 500 in one embodiment of this application. Detailed Implementation

[0026] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0027] See Figures 1-2A composite sleeve 100, installed on a capacitor, includes an insulating tube 200, an umbrella sleeve 300 covering the outer periphery of the insulating tube 200, and upper fittings 400 and lower fittings 500 respectively fitted at both ends of the insulating tube 200. The insulating tube 200 is a hollow tube made of composite material, possessing advantages such as light weight, high structural strength, and good bending and tensile strength. The insulating tube 200 can be a hollow pultruded tube formed by pultrusion and winding of glass fiber or aramid fiber impregnated with epoxy resin, or a fiberglass tube formed by winding and curing glass fiber impregnated with epoxy resin or by pultrusion, or an aramid fiber tube formed by winding and curing aramid fiber impregnated with epoxy resin; no limitation is made herein.

[0028] The umbrella sleeve 300 is made of silicone rubber compound, which is integrally injected onto the outer periphery of the insulating tube 200 through high temperature and high pressure. This high-temperature vulcanization process places high demands on the thermal stability and mechanical strength of the insulating tube 200. The insulating tube 200 made of the above-mentioned composite material has excellent high temperature resistance, oil resistance, corrosion resistance, and aging resistance. It can maintain structural integrity under these process conditions without deformation or cracking, thus ensuring the molding quality of the umbrella sleeve 300. In addition, when faced with external vibration and impact, the insulating tube 200 made of composite material exhibits good toughness and impact resistance, and will not shatter or explode instantly, significantly improving safety and reliability.

[0029] One end of the insulating tube 200 is mounted on the capacitor, and the other end is used to connect to an external circuit. The end of the insulating tube 200 furthest from the capacitor is defined as the first end 201 of the insulating tube 200, and the end of the insulating tube 200 closest to the capacitor is defined as the second end 202 of the insulating tube 200. The upper fitting 400 is fixedly connected to the first end 201 of the insulating tube 200, and the lower fitting 500 is fixedly connected to the second end 202 of the insulating tube 200.

[0030] Combination Figures 3-4In one embodiment, the upper fitting 400 includes a bolt 410, a connector 420, and a stranded wire 430. One end of the stranded wire 430 is fixedly connected to the bolt 410, and the other end passes through the hollow inner cavity of the insulating tube 200 and extends out of the second end 202 of the insulating tube 200. The connector 420 includes a connecting part 421 and a first connecting cylinder 422 that are connected to each other. Both the connecting part 421 and the first connecting cylinder 422 are hollow cylindrical structures. The diameter of the connecting part 421 is smaller than the diameter of the first connecting cylinder 422. The connecting part 421 and the first connecting cylinder 422 are connected by an end cap 423 and are integrally formed. The axis of the connecting part 421 coincides with the axis of the first connecting cylinder 422. The end cap 423 seals one side opening of the first connecting cylinder 422. The end cap 423 has a through hole in its center. The connecting part 421 is disposed on the through hole and is located on the end face of the end cap 423 away from the first connecting cylinder 422, so that the hollow cavity of the connecting part 421 is connected to the hollow cavity of the first connecting cylinder 422, thereby making the connecting part 421, the end cap 423 and the first connecting cylinder 422 together form a continuous hollow structure. The inner diameter of the connecting part 421 is matched with the outer diameter of the bolt 410. The connecting part 421 is welded to the bolt 410 to achieve a sealed connection, resulting in high structural strength of the upper fitting 400. The inner diameter of the first connecting cylinder 422 matches the outer diameter of the insulating tube 200. The first connecting cylinder 422 is glued to the insulating tube 200 for a sealed connection. Sealant is applied between the contact surfaces of the first connecting cylinder 422 and the insulating tube 200 to achieve a sealed connection between the connecting part 420 and the insulating tube 200. Specifically, when the first connecting cylinder 422 is fitted onto the outer periphery of the end of the insulating tube 200, the end face of the insulating tube 200 abuts against the end cap 423, so that the upper fitting 400 is tightly fixed to the first end 201 of the insulating tube 200. To improve the bonding strength between the connecting part 420 and the insulating tube 200, the inner wall of the first connecting cylinder 422 is ground or sandblasted before assembly, effectively improving the bonding performance. The connection between the end cap 423 and the connecting part 421 is chamfered, which can reduce the stress concentration at the connection between the end cap 423 and the connecting part 421.

[0031] An annular groove 210 is provided on the outer periphery of the first end 201 of the insulating tube 200, so that the outer diameter of this end is smaller than the outer diameter of the rest of the insulating tube 200, which facilitates the insertion of the insulating tube 200 into the first connecting cylinder 422. After the first connecting cylinder 422 is sleeved on the first end 201 of the insulating tube 200, the annular groove 210 forms a sealing cavity between the insulating tube 200 and the first connecting cylinder 422 to accommodate the sealant. During the assembly process, the sealing cavity is filled with epoxy resin sealant, which effectively increases the bonding area and the volume of the adhesive layer, avoids the problem of the adhesive layer being too thin and easy to crack, and significantly improves the mechanical strength and long-term reliability of the connection. After the epoxy resin sealant is cured, it forms a high-strength adhesive layer, which not only achieves a firm connection between the insulating tube 200 and the upper hardware 400, but also has good electrical insulation performance and environmental sealing performance. Furthermore, a sealing groove (not shown in the figure) is provided on the inner wall of the first connecting cylinder 422. The sealing groove is located on the mating surface formed after the connector 420 and the insulating tube 200 are assembled. Specifically, the sealing groove is located in the quarter region of the mating surface near the free end of the first connecting cylinder 422, and the sealing groove and the annular groove 210 are spaced apart axially on the first connecting cylinder 422. An oil-resistant sealing ring, such as a fluororubber or nitrile rubber sealing ring, is installed in the sealing groove to further improve the sealing performance between the insulating tube 200 and the connector 420, thereby improving the safety and stability of the composite sleeve 100. The free end of the first connecting cylinder 422 is the end of the first connecting cylinder 422 away from the bolt 410. One or more sealing grooves can be provided, and multiple sealing grooves can be spaced apart axially on the first connecting cylinder 422; this is not limited here.

[0032] A connecting hole 411 is provided at one end of the bolt 410 near the connector 420. In this embodiment, the connecting hole 411 is a countersunk hole, axially located at the end of the bolt 410 near the insulating tube 200. During assembly, after the bolt 410 is fixedly connected to the connector 420, the stranded wire 430 extends into the connecting hole 411 and is fixed in the connecting hole 411 by crimping, giving it high tensile strength, ensuring good electrical contact, and preventing the stranded wire 430 from loosening or falling off during use. The free end of the stranded wire 430 passes through the hollow inner cavity of the insulating tube 200 and extends out of the second end 202 of the insulating tube. When the second end 202 of the insulating tube 200 is fixedly connected to the capacitor, the free end of the stranded wire 430 extends and is fixed inside the capacitor, thereby realizing the electrical connection between the external circuit and the inside of the capacitor. During the assembly of the composite sleeve 100, before fixing the first connecting cylinder 422 to the insulating tube 200, the stranded wire 430 must first be fixed in the connecting hole 411. In other embodiments, the connecting hole can also be a threaded hole, as long as it can fix the stranded wire, and there is no limitation here.

[0033] In this embodiment, both bolt 410 and connector 420 are made of stainless steel, possessing excellent corrosion resistance and mechanical strength. The stranded wire 430 is made of copper, and its cross-sectional area and number of strands are selected based on the current required by the equipment. To improve the durability and reliability of the stranded wire 430 in complex environments, its surface undergoes an oxidation treatment to form a dense protective oxide film, preventing oxidation and corrosion. Compared to rigid conductive rods, the stranded wire 430 has significant advantages in flexibility and adaptability, making it easier to bend and adjust its direction during installation. In contrast, rigid conductive rods require precise alignment, increasing installation difficulty. The stranded wire 430 can also deform under impact and vibration to avoid stress concentration and fatigue damage caused by rigid contact, providing higher reliability and durability. In other embodiments, bolts and connectors can also be made of other oil- and corrosion-resistant materials, as long as they meet the application requirements; no limitations are imposed here.

[0034] Combination Figures 5-6 The lower fitting 500 is fixedly connected to the second end 202 of the insulating tube 200. The lower fitting 500 includes a second connecting cylinder 510 and a flange 520. The second connecting cylinder 510 is a hollow cylindrical structure, and the flange 520 extends radially from the outer wall of one end of the second connecting cylinder 510 outward, forming a disc-shaped structure. The inner diameter of the second connecting cylinder 510 matches the outer diameter of the insulating tube 200. The second connecting cylinder 510 is sealed to the insulating tube 200 by adhesive bonding. The axial extension direction of the second connecting cylinder 510 is aligned with the central axis of the insulating tube 200 to ensure the coaxiality and uniform stress distribution of the overall structure. The flange 520 is integrally formed with the second connecting cylinder 510, and the lower fitting 500 is welded and fixed to the capacitor through the flange 520, thereby installing the composite sleeve 100 onto the capacitor.

[0035] Since the insulating tube 200 needs to extend into the capacitor for electrical connection and structural support, mounting holes for the insulating tube 200 must be made on the capacitor's connection end face. However, during the machining of these mounting holes, especially when using mechanical drilling or laser cutting, uneven local stress release or material thermal deformation can easily cause slight warping of the capacitor's connection end face, reducing its flatness. This can lead to the insulating tube 200 not being properly assembled during assembly, resulting in tilting or eccentricity. This can cause uneven stress on the sealing structure and local stress concentration, potentially leading to seal failure or mechanical damage, affecting the equipment's insulation performance and operational reliability. To ensure that the flange 520 is properly assembled with the capacitor and to prevent stress concentration or seal failure due to warping or misalignment, the flange 520's surface is designed to be non-planar.

[0036] Specifically, in this embodiment, the disc surface of the flange 520 away from the second connecting cylinder 510 includes, from the inside to the outside, a first support surface 521, a second support surface 522, and a third support surface 523 along its radial direction. From the inside to the outside specifically means along the radial direction of the second connecting cylinder 510 from the outer wall of the second connecting cylinder 510 away from the second connecting cylinder 510. The first support surface 521, the second support surface 522, and the third support surface 523 are all parallel to the radial direction of the second connecting cylinder 510. At the same time, the first support surface 521, the second support surface 522, and the third support surface 523 are located in different planes and are parallel to each other, so that the flange 520 constitutes a non-planar structure, which can tolerate the unevenness of the capacitor mounting end face to a certain extent and achieve precise fit with the capacitor connection end face.

[0037] The first support surface 521 is located in the inner ring area of ​​the flange 520 and connects to the outer wall of the second connecting cylinder 510, serving as an auxiliary support. The second support surface 522 is located outside the first support surface 521 and is a horizontal platform. The end of the second connecting cylinder 510 that is not connected to the flange 520 is defined as the top end of the second connecting cylinder 510. The distance between the plane of the second support surface 522 and the plane of the top end of the second connecting cylinder 510 is less than the distance between the plane of the first support surface 521 and the plane of the top end of the second connecting cylinder 510. The distance between the plane of the support surface 522 and the plane of the first support surface 521 is 0.5mm. The third support surface 523 is located in the outermost area of ​​the flange 520 and is the main mounting surface that contacts the connection end face of the capacitor. The distance between the plane of the third support surface 523 and the plane of the top end of the second connecting cylinder 510 is greater than the distance between the plane of the first support surface 521 and the plane of the top end of the second connecting cylinder 510, and the distance between the plane of the third support surface 523 and the plane of the first support surface 521 is 0.5mm. That is, when the third support surface 523 is completely attached to and fixedly connected to the connection end face of the capacitor, there is a 0.5mm reserved gap between the first support surface 521 and the connection end face of the capacitor. The first support surface 521 does not directly contact the capacitor end face during normal assembly. Even if there is slight warping or deformation around the mounting hole of the capacitor, the flange 520 can still achieve a stable and flat fit through the outer ring of the third support surface 523. At this point, the assembly load is mainly borne by the third support surface 523, which effectively avoids the warping or deformation area around the mounting hole, thereby preventing problems such as tilting of the composite sleeve 100 or sealing failure caused by deformation of the capacitor's connection end face. Simultaneously, a 1mm reserved gap exists between the second support surface 522 and the capacitor connection end face. When the flange 520 is subjected to external pressure, this reserved gap helps release local stress and prevents pressure damage to the flange 520. In other embodiments, the distance between the plane containing the second support surface and the plane containing the first support surface can also be set to any value less than or equal to 1mm, and the distance between the plane containing the third support surface and the plane containing the first support surface can also be set to any value less than or equal to 1mm; no restrictions are imposed here. The flange can also be set to other non-planar shapes, as long as it enables a stable and flat fit between the insulating sleeve and the capacitor mounting end face; no restrictions are imposed here.

[0038] Furthermore, since the first support surface 521, the second support surface 522, and the third support surface 523 are located in different planes, the flange 520 also includes a first transition surface 524 and a second transition surface 525. In this embodiment, the first transition surface 524 is an inclined surface that extends upward from the first support surface 521 and connects to the second support surface 522, forming a transition inclined surface. When the flange 520 is subjected to external pressure, this helps to release local stress and reduce stress concentration. The second transition surface 525 is a vertical surface that extends downward from the second support surface 522 along the axial direction of the flange 520 and connects to the third support surface 523. The second transition surface 525 provides axial support to the flange 520 and also works with the second support surface 522 to increase the structural rigidity of the flange 520. In other embodiments, the first transition surface and the second transition surface can both be set as inclined surfaces, vertical surfaces, or transition surfaces of other shapes, as long as the structural strength of the flange can be guaranteed, and there are no restrictions here.

[0039] Furthermore, the surfaces of the upper fitting 400 and the lower fitting 500 are treated with anti-corrosion paint. The anti-corrosion paint coating adopts a corrosion-resistant and salt spray-resistant coating system, such as epoxy resin paint, to form a dense protective layer, which further improves the overall corrosion resistance, salt spray aging resistance and appearance quality of the product, and enhances the operational safety and reliability of the composite sleeve 100 in harsh environments.

[0040] See again Figures 1-2 After the upper fitting 400 and lower fitting 500 are installed in conjunction with the insulating tube 200, a silicone rubber umbrella sleeve 300 is formed on the outside using a high-temperature vulcanization process. The umbrella sleeve 300 is made of high-temperature vulcanized solid silicone rubber, which has excellent hydrophobicity, aging resistance, and salt spray corrosion resistance. To improve the interfacial bonding strength between the silicone rubber material and the insulating tube 200, upper fitting 400, and lower fitting 500, and to prevent defects such as debonding and cracking during long-term operation, a coupling agent is uniformly coated on the surfaces of the insulating tube 200, upper fitting 400, and lower fitting 500 before high-temperature vulcanization to improve interfacial stability. The umbrella sleeve 300 includes an umbrella skirt 310 and a sheath 320, used to improve the product's creepage distance and pollution flashover resistance. The umbrella sleeve 300 needs to completely cover the transition area between the insulating tube 200 and the upper fitting 400 and the lower fitting 500. The covering length at both ends of the umbrella sleeve 300 extends 20-40mm along the axial direction of the insulating tube 200 to the upper fitting 400 and the lower fitting 500 respectively, effectively blocking the intrusion of pollutants such as moisture, salt spray, and dust along the interface and improving the insulation reliability of the product.

[0041] The umbrella skirt 310 comprises several umbrellas of equal diameter. The extension length of the umbrella skirt 310 can be designed according to the voltage level to meet different electrical insulation requirements. The umbrella skirt 310 includes an upper umbrella surface and a lower umbrella surface. The upper umbrella surface is the exposed surface of the umbrella skirt facing away from the capacitor after the composite sleeve 100 is fixedly installed with the capacitor. The lower umbrella surface is the exposed surface of the umbrella skirt facing the capacitor. The upper and lower umbrella surfaces together form the outer surface of the umbrella skirt. The acute angle formed between the tangent of the upper umbrella surface and the radial direction of the insulating tube is defined as the upward tilt angle α, where 5° < α < 15°; the acute angle formed between the tangent of the lower umbrella surface and the radial direction of the insulating tube is defined as the downward tilt angle β, where β = α. This symmetrical arrangement of the upper and lower umbrella surfaces facilitates rainwater flow, reduces dirt accumulation, optimizes the electric field distribution, and suppresses wet flashover and pollution flashover.

[0042] The beneficial effects of this application are: the composite sleeve of this application has the advantages of light weight and high structural strength, and has excellent high temperature resistance, oil resistance, corrosion resistance, aging resistance and impact resistance.

[0043] Meanwhile, compared to rigid conductive rods, the stranded wires of the fittings in this application can be bent and adjusted more easily during installation. When faced with impact and vibration, they can avoid stress concentration and fatigue damage through deformation, thus providing higher reliability and durability.

[0044] Furthermore, the flange of the fitting in this application is set to be non-planar, which can tolerate the unevenness of the capacitor mounting end face to a certain extent, achieve precise fit with the capacitor connection end face, and avoid problems such as tilting of the composite sleeve installation or sealing failure caused by deformation of the capacitor connection end face.

[0045] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A composite sleeve, characterized in that, It includes an insulating tube, an umbrella sleeve covering the outer periphery of the insulating tube, and upper and lower fittings respectively fitted at both ends of the insulating tube. The insulating tube is a hollow tube made of composite material. The upper fitting is fixedly connected to the first end of the insulating tube, and the lower fitting is fixedly connected to the second end of the insulating tube. The upper hardware includes a bolt, a connector, and a stranded wire. The connector includes a connecting part and a first connecting cylinder that are connected to each other. The connecting part is sealed to the bolt, and the first connecting cylinder is sealed to the insulating tube. One end of the stranded wire is fixedly connected to the bolt, and the other end passes through the hollow inner cavity of the insulating tube and extends out of the second end of the insulating tube. The lower fitting includes a second connecting cylinder and a flange. The flange extends outward from the outer wall of one end of the second connecting cylinder along the radial direction of the second connecting cylinder. The flange has a disc-shaped structure and is a non-planar structure.

2. The composite sleeve as described in claim 1, characterized in that, The first end of the insulating tube has an annular groove on its outer periphery, so that a sealing cavity for accommodating sealant is formed between the insulating tube and the first connecting cylinder.

3. The composite sleeve as described in claim 1, characterized in that, Both the connecting part and the first connecting cylinder are hollow cylindrical structures. The diameter of the connecting part is smaller than the diameter of the first connecting cylinder. The connecting part and the first connecting cylinder are connected by an end cap and integrally formed. The end cap covers one side opening of the first connecting cylinder. The end cap has a through hole in the center. The connecting part is disposed on the through hole and located on the end face of the end cap away from the first connecting cylinder.

4. The composite sleeve as described in claim 1, characterized in that, The inner wall of the first connecting cylinder is provided with a sealing groove, which is located on the mating surface formed after the connecting member and the insulating tube are assembled.

5. The composite sleeve as described in claim 1, characterized in that, The bolt has a connecting hole at one end near the connector, and the stranded wire extends into the connecting hole and is fixed by crimping.

6. The composite sleeve as described in claim 1, characterized in that, The flange, located away from the second connecting cylinder, includes a first support surface, a second support surface, and a third support surface in its radial direction from the inside to the outside. The first support surface, the second support surface, and the third support surface are located in different planes and are parallel to each other.

7. The composite sleeve as described in claim 6, characterized in that, The distance between the plane containing the second support surface and the plane containing the top end of the second connecting cylinder is less than the distance between the plane containing the first support surface and the plane containing the top end of the second connecting cylinder; the distance between the plane containing the third support surface and the plane containing the top end of the second connecting cylinder is greater than the distance between the plane containing the first support surface and the plane containing the top end of the second connecting cylinder.

8. The composite sleeve as described in claim 7, characterized in that, The distance between the plane containing the second support surface and the plane containing the first support surface is 0.5 mm, and the distance between the plane containing the third support surface and the plane containing the first support surface is 0.5 mm.

9. The composite sleeve as described in claim 6, characterized in that, The flange includes a first transition surface, which is an inclined surface. The first transition surface extends upward from the first support surface and connects to the second support surface.

10. The composite sleeve as described in claim 6, characterized in that, The flange includes a second transition surface, which is a vertical surface. The second transition surface extends downward from the second support surface along the axial direction of the flange and connects to the third support surface.

11. The composite sleeve as described in claim 1, characterized in that, The umbrella cover covers the transition area between the insulating tube and the upper and lower fittings, and the covering length at both ends of the umbrella cover extends 20-40mm along the axial direction of the insulating tube towards the upper and lower fittings, respectively.

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