A cable branch box

Abstract

The application discloses a cable branch box, which comprises a box body and a wire inlet mechanism, wherein the wire inlet mechanism is located at the bottom of the box body of the cable branch box and comprises a wire inlet pipe, a plurality of sealing skirts are coaxially inserted into the wire inlet pipe from bottom to top, the skirt umbrella end of the sealing skirt with a large opening is downward and the outer edge is in abutment with the inner wall of the wire inlet pipe, and the wire sleeve end with a small opening is used for passing through the cable; the diameter of the wire sleeve end of each sealing skirt is gradually reduced, the diameter of the wire sleeve end of the uppermost skirt is equal to the diameter of the cable; the wire inlet pipe is filled with a sealing glue body of a cured sealing glue from bottom to top, the space between the first skirt and the lower end of the wire inlet pipe and the space between each sealing skirt are filled, a plurality of levels of series connection physical barriers are formed by the multistage variable-diameter sealing skirts and the sealing glue in cooperation with the filling, and the gap between the cable and the hole wall is eliminated; meanwhile, the sealing glue body is divided into a plurality of independent micro-motion areas, actively absorbs thermal expansion deformation, and realizes a multi-level, self-adaptive and anti-separation sealing effect, so that the sealing reliability and long-term durability are remarkably improved.

Description

Technical Field

[0001] This application relates to power grid shunt devices, and more particularly to a cable branch box. Background Technology

[0002] Cable distribution boxes are typically installed in outdoor power distribution systems, with an inlet at the bottom for cable entry. In existing technology, this inlet is often a circular hole directly drilled in the steel plate at the bottom of the box, through which the cable passes directly into the box. However, due to the inevitable bending and twisting of cables during actual installation, their cross-section is not perfectly circular, often resulting in irregular gaps between the cable's outer wall and the hole wall. These gaps allow moisture, insects, and other external substances to enter the cable distribution box, leading to condensation and even accidental short circuits, seriously affecting the safety and reliability of the equipment.

[0003] To address the aforementioned issues, existing technologies propose installing a rubber sleeve over the cable, ensuring a tight fit between the outer wall of the rubber sleeve and the wall of the bore, and injecting insulating sealant into the rubber sleeve to fill the gap between the inner wall of the rubber sleeve and the outer wall of the cable. However, this solution still has significant drawbacks: the rubber sleeve is only fixed to the bottom of the enclosure via an interference fit, making it difficult to completely eliminate the gap between them. Furthermore, the rubber sleeve exerts a downward pulling force on the cable, which may lead to cable deformation or displacement under long-term stress.

[0004] Another existing technology involves welding a metal sleeve directly to the bottom of the enclosure to replace the rubber sleeve, attempting to improve sealing through a rigid connection. However, the bonding strength between the inner wall of the metal sleeve and the insulating sealant is relatively low, and the thermal expansion coefficients of the metal and the sealant differ significantly. Under temperature changes, separation easily occurs at the bonding interface between the two, making it easier to form new gaps than with the rubber sleeve, thus failing to effectively prevent moisture and insects from entering the enclosure.

[0005] Therefore, there is an urgent need for a cable branch box inlet mechanism that is simple in structure, reliable in sealing, and highly adaptable, in order to solve the problems of poor sealing, insufficient bonding strength, and thermal stress cracking in the existing technologies. Summary of the Invention

[0006] In order to overcome the shortcomings of existing technologies such as poor sealing at the cable inlet of cable distribution boxes, easy intrusion of moisture and insects into the box, and easy failure of the sealing structure due to thermal stress, this application provides a cable distribution box.

[0007] The above-mentioned objective of this invention is achieved through the following technical solutions: A cable branch box includes a box body and an inlet mechanism located at the bottom of the box body, including an inlet pipe, wherein a plurality of sealing skirts are coaxially inserted into the inlet pipe, and the plurality of sealing skirts are distributed sequentially from bottom to top; The sealed skirt cover has a large opening at one end and a small opening at the other end. The end with the large opening is the umbrella end of the skirt, and the end with the small opening is the thread end. The umbrella ends of the sealing skirt all face downwards, and the outer edge of the umbrella end fits and abuts against the inside of the inlet pipe; The cable is passed through the sleeve end; The sealed skirts are arranged from bottom to top as the first skirt, the second skirt, and so on up to the Nth skirt. The diameter of the cable end of the first skirt cover, the second skirt cover to the Nth skirt cover decreases step by step. The diameter of the cable end of the first skirt cover is greater than the diameter of the cable, and the diameter of the cable end of the Nth skirt cover is equal to the diameter of the cable. The inlet pipe is filled with a cured sealant from bottom to top, and the sealant fills the space between the first skirt and the bottom of the inlet pipe and the space between the sealing skirt.

[0008] By adopting the above technical solutions, with the dual technical concepts of "multi-stage variable diameter sealing skirt and sealant co-filling" and "the sealing skirt dividing the overall sealant into multiple areas that can be independently micro-deformed", the problems existing in the background technology, such as the gap between the cable and the hole wall leading to the intrusion of moisture and insects, the gap and downward tension caused by the interference fit of the rubber sleeve, and the separation of the bonding interface caused by the difference in the thermal expansion coefficients of the metal sleeve and the sealant, are systematically solved. Firstly, at the structural level, multiple sealing skirts are coaxially inserted into the inlet pipe, arranged sequentially from bottom to top. The umbrella end of each skirt faces downward and fits against the inner wall of the inlet pipe. The diameter of the sleeve end decreases step by step, with the diameter of the sleeve end of the uppermost skirt being equal to the diameter of the cable. This structure forms a multi-stage series of physical barriers: external moisture or insects must pass through the contact surface between each level of the umbrella end and the pipe wall, significantly extending the path. At the same time, the variable diameter design ensures that the uppermost skirt tightly hugs the cable surface, eliminating annular gaps, while the lower skirts form a conical transition cavity to accommodate the non-circular cross-section caused by the bending and twisting of the cable, avoiding single-stage seal failure. After the sealant cures, it fills the space between the first skirt and the lower end of the inlet pipe, as well as between each sealing skirt, firmly bonding and positioning each skirt without relying on interference fit. This eliminates the gaps caused by improper assembly of the rubber sleeve and the downward pull on the cable. Secondly, in terms of thermal stress relief, the sealing skirt divides the originally monolithic sealing compound into multiple independent segments along the axial direction. The absolute size of each segment is significantly reduced, and the absolute amount of thermal expansion change is correspondingly reduced. At the same time, the outer edge of the skirt umbrella end is flexibly fitted to the inner wall of the inlet pipe, allowing for slight displacement during temperature changes. The sealing skirt itself can undergo elastic angular deformation ("pointing upward"), actively absorbing the volume change caused by the expansion of the sealing compound. This "segmentation + micro-motion + deformation energy absorption" mechanism allows the thermal deformation stress to be dissipated step by step before it is transmitted to the bonding interface between the sealing compound and the inner wall of the inlet pipe, significantly reducing the tearing force acting on the bonding interface and avoiding interface separation failure caused by the difference in thermal expansion coefficients in traditional metal sleeve structures. In summary, a multi-layered, adaptive, and anti-separation sealing system is constructed through the synergistic effects of multi-stage skirt sealing, pressure adaptive tightening, continuous filling of sealant to form an interface-free sealing layer, and skirt segmentation of the colloid and micro-deformation to absorb thermal stress. This system breaks through the existing approach of using a single sealing element or a single adhesive fixation, organically combining mechanical sealing, material compatibility, and thermal stress compensation, significantly improving the sealing reliability and long-term durability of the cable branch box inlet mechanism under different working conditions.

[0009] Optionally, the inner side of the inlet pipe is coaxially provided with a protruding limiting ring, the number of which is equal to that of the sealing skirt; except for the Nth skirt, the outer edge of the remaining sealing skirts is independently inserted between two limiting rings.

[0010] By adopting the above technical solution, the spacer groove formed by the limiting ring is used to axially position each skirt and guide the skirts into place one by one during installation. After installation, part of the weight of the sealing skirt and sealant filler is transferred to the inlet pipe and the enclosure via the limiting ring. The purpose is to facilitate accurate positioning during installation and to distribute the weight load of the cable, sealing skirt, and sealant to the enclosure structure, reducing the direct downward pulling force on the cable.

[0011] Optionally, the limiting ring is formed by the inlet pipe wall being squeezed inward and bulging.

[0012] By adopting the above technical solution, the limiting ring is formed by the inlet pipe wall being squeezed inward; this integrated protrusion structure can generate axial tensile deformation and outward ejection deformation when the inlet pipe is subjected to internal radial pressure, thereby adapting to the thermal expansion and contraction deformation of the sealant filler. Thus, the elastic micro-deformation of the limiting ring itself is used to compensate for the volume change of the sealant, reduce the rigid constraint stress between the limiting ring and the sealant, and further improve the long-term stability of the sealing structure.

[0013] Optionally, the inner side of the sealing skirt is provided with a threaded strip that screws inward from the outer edge.

[0014] By adopting the above technical solution, when the uncured sealant is pressurized between the two sealing skirts or subjected to pressure along the axial direction of the feed sleeve, the threaded strip guides the sealant to flow towards the center and outward along the spiral path, promoting uniform distribution of the sealant and filling all corners, improving the filling efficiency and density of the sealant, avoiding cavities or air bubbles, and ensuring that the gaps between each sealing layer are fully sealed.

[0015] Optionally, the inner edge of the smaller opening of the Nth skirt cover has a double-lip sealing ring.

[0016] By adopting the above technical solution, a double-lip sealing ring is set on the inner edge of the smaller opening of the Nth skirt sleeve. The double-lip sealing ring forms two contact sealing lines with the cable surface, which not only enhances the final sealing effect, but also plays a temporary sealing role during installation. This prevents the uncured sealant from being squeezed out from the top due to temperature rise or exothermic expansion during curing, and avoids excessive shrinkage stress inside the sealant after curing, which would lead to a decrease in the interfacial bonding force with the inner wall of the inlet pipe. This improves the sealing reliability of the uppermost sealing point and optimizes the stress state during the curing process of the sealant.

[0017] Optionally, during installation, first install the first skirt at the feed inlet, fill with sealant, then install the second skirt, fill with sealant again, and repeat the operation until installation is complete.

[0018] By adopting the above technical solution, during installation, the first skirt is installed on the inlet pipe and filled with sealant, then the second skirt is installed and filled with sealant again, and this process is repeated until all skirts are installed. This layer-by-layer installation and sealant injection ensures that each layer of sealant is initially positioned and filled before the next skirt is installed, avoiding uneven sealant flow or air bubble retention caused by a single injection. The purpose is to ensure that the sealant fills the spaces between skirts and at the bottom densely and continuously without gaps, guaranteeing the overall integrity of the sealing system.

[0019] Optionally, the cone angle of the first skirt, the second skirt, and so on up to the Nth skirt increases progressively.

[0020] By adopting the above technical solution, the cone angle of the first, second, and Nth skirts increases progressively. As the skirt layers increase, the cone angle of the skirts gradually becomes larger, resulting in a gradient increase in the radial clamping force of each skirt on the cable. The uppermost skirt provides the maximum clamping force, while the lower skirts provide progressive guidance and support. The purpose is to optimize the smoothness of cable insertion and to assign sealing and fixing functions in stages, further improving the sealing effect and installation convenience.

[0021] In summary, this application has at least the following beneficial effects: 1. Through the synergistic filling of multi-stage variable diameter sealing skirts and sealant, a multi-stage series physical barrier is formed, which effectively eliminates the annular gap between the cable and the hole wall, prevents moisture and insects from entering the box, and avoids condensation and accidental short circuits. 2. The sealing skirt divides the overall sealing colloid into multiple independent segments. Combined with the micro-movement of the outer edge of the skirt umbrella end and the elastic angle deformation of the skirt itself, it actively absorbs the volume change caused by thermal expansion, significantly reducing the tearing force acting on the bonding interface and avoiding interface separation failure caused by the difference in thermal expansion coefficient. 3. After the sealant cures, each skirt is firmly bonded and positioned, eliminating the need for interference fit and removing gaps caused by improper assembly of the rubber sleeves and the downward pull on the cables; 4. Optional structures such as limit rings, threaded strips, and double-lip sealing rings can be set to further optimize installation positioning, sealant filling efficiency, and the sealing effect of the uppermost layer, thereby improving the integrity and long-term stability of the overall sealing system. Attached Figure Description Figure 1 Schematic diagram of cable branch box Figure 1 ; Figure 2 Schematic diagram of cable branch box Figure 2 ; Figure 3 This is a schematic diagram of the infeed mechanism; Figure 4 This is a sectional view of the infeed mechanism; Figure 5 An exploded view of the sealed skirt cover; Figure 6 This is a schematic diagram of the sealing skirt structure.

[0022] Figure label: 1. Inlet mechanism; 11. Inlet pipe; 111. Limiting ring; 1111. Upper limit ring; 1112. First intermediate limit ring; 1113. Second intermediate limit ring; 1114. Lower limit ring; 12. Sealing skirt; 12a. First skirt; 12b. Second skirt; 12c. Third skirt; 12d. Fourth skirt; 121. Skirt end; 122. Cable end; 123. Double lip sealing ring; 124. Threaded strip; 13. Sealing colloid; 2. Enclosure; 21. Mounting bracket; 22. Enclosure door; 23. Hinge; 24. Circuit breaker; 3. Cable. Detailed Implementation

[0023] As attached Figure 1 As shown, a cable branch box includes a box body 2 and multiple cable inlet mechanisms 1 installed at the bottom of the box body.

[0024] The enclosure 2 is welded from stainless steel or aluminum alloy sheets, providing excellent corrosion resistance and mechanical strength. Inside the enclosure 2 are mounting brackets 21 for fixing and supporting electrical components, which are bolted to the back or side panels of the enclosure 2. The front of the enclosure 2 has an openable door 22, which is rotatably connected to the enclosure 2 via hinges 23.

[0025] A circuit breaker 24 is installed on the mounting bracket 21 for connecting cables and controlling the opening and closing of the circuit.

[0026] As attached Figure 2 As shown, the cable inlet mechanism 1 includes a cable inlet pipe 11, which is a vertically arranged metal pipe welded to the ground of the housing 2. The lower end of the cable inlet pipe 11 extends out of the bottom of the housing 2, and the upper end of the cable inlet pipe 11 extends into the interior of the housing 2.

[0027] As attached Figure 3 As shown, multiple sealing skirts 12 are coaxially inserted into the inner side of the inlet pipe 11, and the multiple sealing skirts 12 are distributed sequentially from bottom to top.

[0028] As attached Figure 4 As shown, the sealing skirt 12 is made of an elastomer material, such as silicone rubber or EPDM rubber. Each sealing skirt 12 is truncated conical in shape, with a large opening at one end and a small opening at the other. The end with the large opening is defined as the skirt end 121, and the end with the small opening is defined as the sleeve end 122.

[0029] As attached Figure 3 As shown, the umbrella ends 121 of all sealing skirts 12 are arranged downwards, and the outer edge of the umbrella end 121 is in close contact with the inner wall of the inlet pipe 11 to form a flexible sealing contact. The cable end 122 is for the cable 3 to pass through.

[0030] The sealing skirts 12 are arranged from bottom to top as follows: first skirt 12a, second skirt 12b, third skirt 12c, ... up to the Nth skirt. N is a positive integer greater than or equal to 2; in this embodiment, N=4, meaning four sealing skirts 12 are provided. The diameter of the thread end 122 of the first skirt 12a, second skirt 12b, third skirt 12c, and fourth skirt 12d decreases progressively.

[0031] As attached Figure 3 and attached Figure 4 As shown, the diameter of the cable end 122 of the first skirt 12a is larger than the outer diameter of the cable 3, and the diameter of the cable end 122 of the fourth skirt 12d is equal to the outer diameter of the cable 3. Simultaneously, the cone angle of each sealing skirt 12 increases progressively: the cone angle of the fourth skirt 12d is larger than that of the third skirt 12c, the cone angle of the third skirt 12c is larger than that of the second skirt 12b, and the cone angle of the second skirt 12b is larger than that of the first skirt 12a.

[0032] As attached Figure 3 As shown, the inlet pipe 11 is filled with a sealant 13 formed by the curing of sealant from the bottom to the top. The sealant 13 fills the space between the first skirt 12a and the lower end of the inlet pipe 11, as well as the space between adjacent sealing skirts 12—between the first skirt 12a and the second skirt 12b, between the second skirt 12b and the third skirt 12c, between the second skirt 12b and the third skirt 12c, and between the third skirt 12c and the fourth skirt 12d.

[0033] The sealing colloid 13 is made of epoxy resin potting compound or polyurethane potting compound, which has good insulation and bonding strength after curing.

[0034] The inner side of the inlet pipe 11 is coaxially provided with a protruding limiting ring 111. The number of limiting rings 111 is one more than the number of sealing skirts 12. In this embodiment, four limiting rings 111 are provided, namely an upper limiting ring 1111, a first intermediate limiting ring 1112, a second intermediate limiting ring 1113, and a lower limiting ring 1114. Except for the fourth skirt 12d, the outer edge of each sealing skirt 12 is independently inserted between two adjacent limiting rings 111. Specifically, the outer edge of the first skirt 12a is inserted between the lower limiting ring 1114 and the second intermediate limiting ring 1113, the outer edge of the second skirt 12b is inserted between the second intermediate limiting ring 1113 and the first intermediate limiting ring 1112, the outer edge of the third skirt 12c is inserted between the first intermediate limiting ring 1112 and the upper limiting ring 1114, and the outer edge of the fourth skirt 12d abuts against the upper end of the upper limiting ring 1111.

[0035] The limiting ring 111 is formed by extruding the wall of the inlet pipe 11 from the outside to the inside, and is an integral structure with the inlet pipe 11.

[0036] As attached Figure 5 As shown, the inner surface of the sealing skirt 12 is provided with a threaded bar 124 that screws inward from the outer edge. The threaded bar 124 extends in a spiral shape along the circumference of the sealing skirt 12, and its spiral direction is from the skirt end 121 to the sleeve end 122.

[0037] As attached Figure 3 and attached Figure 5 As shown, when the uncured sealant is under pressure, the threaded strip 124 guides the sealant to flow towards the center and outward along the spiral path, promoting uniform filling.

[0038] As attached Figure 4 As shown, the inner edge of the cable end 122 of the fourth skirt sleeve 12d has a double-lip sealing ring 123. The double-lip sealing ring 123 has an inner lip and an outer lip, both of which are in close contact with the surface of the cable 3, forming two sealing lines.

[0039] Installation method of the incoming line mechanism: Step S1: Fix the inlet pipe 11 to the bottom of the cable branch box 2, making its axis vertical.

[0040] Step S2: Insert the first skirt cover 12a into the lower end of the inlet tube 11, with its skirt umbrella end 121 facing down and its outer edge inserted between the lower limit ring 111 and the first intermediate limit ring 111.

[0041] Step S3: Inject a certain amount of uncured sealant from the lower end of the inlet pipe 11 to fill the space between the first skirt 12a and the lower end of the inlet pipe 11, and submerge the outer edge of the skirt umbrella end 121 of the first skirt 12a.

[0042] In step S4, when the sealant injected in step S3 has initially gelled but not completely cured, the second skirt sleeve 12b is inserted from the lower end of the inlet pipe 11, with its skirt end 121 facing downwards and its outer edge inserted between the first intermediate limiting ring 111 and the second intermediate limiting ring 111. At this time, a gap remains between the sleeve end 122 of the second skirt sleeve 12b and the cable 3.

[0043] Step S5: Inject uncured sealant again to fill the space between the first skirt 12a and the second skirt 12b.

[0044] Step S6: Repeat the above steps, installing the third skirt cover 12c and the fourth skirt cover 12d in sequence and injecting sealant until all skirt covers are installed. The cable end 122 of the fourth skirt cover 12d tightly hugs the cable 3, and the double-lip sealing ring 123 is in contact with the surface of the cable 3.

[0045] Step S7: Wait for the sealant to fully cure and form a continuous sealant 13.

[0046] The working principle of this embodiment is as follows: Cable 3 enters from the lower end of the inlet pipe 11 and passes sequentially through the cable end 122 of the first skirt 12a, the second skirt 12b, the third skirt 12c, and the fourth skirt 12d. As the diameter of the cable end 122 decreases progressively, cable 3 is guided by a gradually tightening force during insertion, and is finally tightly wrapped by the fourth skirt 12d. The multi-stage sealing skirts 12 form a series of physical barriers, requiring external moisture or insects to pass sequentially through the contact surface between each skirt end 121 and the pipe wall, significantly extending the path.

[0047] After the sealant cures, each skirt is firmly bonded to the inner wall of the inlet pipe 11, filling all gaps. The sealant 13 is divided into multiple independent segments by the sealing skirts 12. Each segment has a small volume, resulting in a correspondingly lower absolute amount of thermal expansion. When the temperature changes, the outer edge of the skirt end 121 can slide slightly on the inner wall of the inlet pipe 11, while the sealing skirt 12 itself undergoes elastic angular deformation (pointing upwards), actively absorbing the volume change of the sealant, thereby reducing the tearing force acting on the bonding interface between the sealant and the inner wall of the inlet pipe 11.

[0048] The limiting ring 111 ensures accurate axial positioning of each skirt and transfers some of the gravity to the wall of the inlet pipe 11, reducing the downward pull on the cable 3. The threaded strip 124 guides the adhesive to flow evenly during the injection process, avoiding air bubble residue. The double-lip sealing ring 123 provides a double seal at the top and prevents uncured sealant from being squeezed out from the top during installation, avoiding shrinkage stress after curing.

[0049] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of protection claimed by the present invention, they are protected by patent law.

Claims

1. A cable branch box, characterized in that, Includes a housing (2) and an inlet mechanism (1) located at the bottom of the housing (2) of the cable branch box, including an inlet pipe (11), wherein multiple sealing skirts (12) are coaxially inserted in the inlet pipe (11), and the multiple sealing skirts (12) are distributed sequentially from bottom to top; The sealing skirt cover (12) has a large opening at one end and a small opening at the other end. The end with the large opening is the skirt umbrella end (121), and the end with the small opening is the sleeve end (122). The umbrella ends (121) of the sealing skirt (12) all face downwards, and the outer edge of the umbrella ends (121) is in close contact with the inside of the inlet pipe (11); The cable end (122) is for the cable (3) to pass through; The sealed skirt covers (12) are arranged from bottom to top as the first skirt cover (12a), the second skirt cover (12b) to the Nth skirt cover; The diameter of the cable end (122) of the first skirt cover (12a), the second skirt cover (12b) to the Nth skirt cover gradually decreases. The diameter of the cable end (122) of the first skirt cover (12a) is greater than the diameter of the cable (3), and the diameter of the cable end (122) of the Nth skirt cover is equal to the diameter of the cable (3). The inlet pipe (11) is filled with a sealant (13) that has been cured with sealant from the bottom up. The sealant (13) fills the space between the first skirt (12a) and the bottom of the inlet pipe (11) and the space between the sealing skirt (12).

2. A cable branch box according to claim 1, characterized in that, The inner side of the inlet pipe (11) is coaxially provided with a protruding limiting ring (111), and the number of the limiting rings (111) is equal to that of the sealing skirt (12); except for the Nth skirt, the outer edge of the remaining sealing skirts (12) is independently inserted between two limiting rings (111).

3. A cable branch box according to claim 2, characterized in that, The limiting ring (111) is formed by the inlet pipe (11) wall being squeezed inward and bulging.

4. A cable branch box according to claim 1, characterized in that, The inner side of the sealing skirt (12) is provided with a threaded strip (124) that screws inward from the outer edge.

5. A cable branch box according to claim 1, characterized in that, The inner edge of the smaller opening of the Nth skirt has a double-lip sealing ring (123).

6. A cable branch box according to claim 1, characterized in that, During installation, first install the first skirt (12a) at the feed inlet, fill it with sealant, then install the second skirt (12b), fill it with sealant again, and repeat the operation until the installation is complete.

7. A cable branch box according to claim 1, characterized in that, The cone angles of the first skirt (12a), the second skirt (12b), and the Nth skirt gradually increase.

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