Waterproof structure and cable branch box

Abstract

The application relates to the technical field of cable branch boxes, in particular to a waterproof structure and a cable branch box, which are applied to the cable branch box and comprise a shell fixedly connected to the inner wall of a cable branch box body, a hydrophobic air-permeable film arranged on one side of the shell, a mesh plate arranged on one side of the hydrophobic air-permeable film, and bolts used for fixing the mesh plate and the shell to clamp and fix the hydrophobic air-permeable film; the lower surface of the shell is communicated with a pipeline, the lower end of the pipeline penetrates through the cable branch box body and is communicated with the outside of the cable branch box body; one end of the pipeline located outside the cable branch box body is provided with a taper groove, and a water inlet sealing structure is arranged in the taper groove. The hydrophobic air-permeable film is arranged, gas exchange between the inside and outside of the box body is allowed to balance pressure, liquid water and water mist in humid air are effectively blocked from entering the box body, and the generation of condensation is fundamentally inhibited.

Description

Technical Field

[0001] This invention relates to the field of cable branch box technology, specifically to a waterproof structure and a cable branch box. Background Technology

[0002] Cable distribution boxes are common equipment in power distribution networks, used for branching, switching, or protecting cable lines. In actual operation, due to diurnal temperature variations, the air inside the box expands and contracts with temperature changes, producing a "breathing effect," that is, the air inside and outside the box exchanges periodically. When humid air from the outside enters the box, it condenses upon cooling, leading to decreased insulation performance, corrosion of metal components, and even short-circuit accidents.

[0003] In existing technologies, physical sealing methods are typically used to prevent moisture intrusion, such as filling the cable inlet with self-leveling resin or fire-retardant putty. However, these sealing materials are prone to aging, cracking, or detachment after long-term use, leading to seal failure and the re-emergence of the "breathing effect." Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a waterproof structure and cable branch box.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a waterproof structure applied to a cable branch box, comprising: A housing fixedly connected to the inner wall of a cable branch box, wherein a hydrophobic and breathable membrane is provided on one side of the housing, and a mesh plate is provided on one side of the hydrophobic and breathable membrane. The mesh plate is fixed to the housing by bolts to clamp and fix the hydrophobic and breathable membrane. The lower surface of the housing is connected to a pipe, and the lower end of the pipe passes through the cable branch box and connects to the outside of the cable branch box. A conical groove is provided at one end of the pipe located outside the cable branch box, and a water inlet sealing structure is provided in the conical groove; The water inlet sealing structure includes a float block disposed below the conical groove, the upper part of the float block having a conical structure that matches the conical groove, and a limit slide rod fixedly connected to the upper surface of the float block; The inner wall of the pipe is fixedly connected to an active sealing structure that can actively seal the pipe.

[0006] Preferably, the active sealing structure includes a sealing ring fixed to the inner wall of the pipe, a conical hole on one side wall of the sealing ring, and a plug with a conical end on one side of the conical hole; a limiting tube is slidably connected to the inner wall of the plug, and a fixing block with a vent hole is fixedly connected to the outer wall of the limiting tube, the outer wall of the fixing block being fixed to the inner wall of the pipe; a first spring is provided on one side of the fixing block, one end of the first spring abutting against the plug; one end of the limiting slide rod extends into the interior of the limiting tube, and a pin hole is provided on the inner wall of the limiting tube, with a fixing structure for limiting the plug provided in the pin hole.

[0007] Preferably, the fixing structure includes a pin, one end of which passes through a pin hole and extends to the blocking side, and the other end of which abuts against the limiting slide rod; a second spring is fixedly connected to one side wall of the pin, one end of which is fixed to the pin hole, and the outer wall of the limiting slide rod is provided with a fixing release structure.

[0008] Preferably, the fixing release structure includes a groove formed in the side wall of the limiting slide bar. When the float moves upward, it drives the limiting slide rod to move upward. When the limiting slide rod moves upward until the groove body is aligned with the pin, the second spring pushes the pin to insert into the groove body, causing the pin to disengage from the limit of the blockage. The first spring then pushes the blockage upward to seal the conical hole.

[0009] Preferably, the cable branch box has an observation port on its side wall, and a transparent observation window is fixedly connected to one side wall of the observation port; a connecting rod is fixedly connected to the side wall of the blockage, and a first magnetic ring is fixedly connected to one end of the connecting rod; a second magnetic ring is slidably fitted on the outer wall of the pipe, and a marking indicator ring is fixedly fitted on the outer wall of the second magnetic ring; two marking grooves are opened on the side wall of the transparent observation window, and the sealing of the blockage is determined by observing the overlapping position of the marking indicator ring with different marking grooves.

[0010] Preferably, one end of the pin is provided with a groove, and a ball is provided in the groove, with the side wall of the ball in contact with the limiting slide bar.

[0011] Preferably, one end of the limiting tube is threadedly connected to a limiting cap, and the inner wall of the limiting cap is slidably connected to the outer wall of the limiting slide rod; a baffle is fixedly sleeved on the outer wall of the limiting slide rod located above the limiting cap.

[0012] Preferably, the hydrophobic and breathable membrane is a polymer waterproof and breathable membrane.

[0013] Preferably, the float is a closed-cell foam plastic or a hollow sealed float.

[0014] A cable branch box includes the aforementioned box body and a waterproof structure.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a hydrophobic and breathable membrane, which allows for gas exchange between the inside and outside of the enclosure to balance pressure, while effectively preventing liquid water and water mist from humid air from entering the enclosure, thus fundamentally suppressing condensation. Compared to the problem of traditional physical sealing materials failing after aging, the hydrophobic and breathable membrane offers stable operation and a long lifespan.

[0016] This invention not only features a float-driven inlet sealing structure but also an active sealing structure driven by a first spring. When the external water level rises, causing the float to move upward and triggering the release mechanism, the pin releases the plug, and the first spring automatically pushes the plug to seal the conical hole, forming a reliable active seal. This dual mechanism ensures that the tank remains effectively sealed even when the sealing material ages or external water accumulates, preventing backflow and making it suitable for low-lying areas prone to flooding.

[0017] This invention utilizes a coordinated design of a first magnetic ring, a second magnetic ring, and a marking indicator ring. The displacement of the blockage is transmitted to the marking indicator ring on the outer wall of the pipe, allowing maintenance personnel to directly determine whether the active sealing structure has been activated through a transparent observation window. Two marking grooves provide clear reference positions, enabling status detection without disassembling the equipment, significantly improving inspection efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 for Figure 1 Enlarged structural diagram at point A; Figure 3 This is a schematic diagram of the first cross-sectional structure of the present invention; Figure 4 This is a schematic diagram of the second cross-sectional structure of the present invention; Figure 5 for Figure 4 Enlarged structural diagram at point B; Figure 6 for Figure 4 Enlarged structural diagram at point C; Figure 7 for Figure 4 Enlarged structural diagram at point D; Figure 8 for Figure 4 Enlarged structural diagram at point E; Figure 9 for Figure 6 Enlarged structural diagram at point F.

[0019] In the diagram: 1. Shell; 2. Hydrophobic and breathable membrane; 3. Mesh plate; 4. Bolt; 5. Pipe; 6. Conical groove; 7. Float; 8. Limiting slide rod; 9. Sealing ring; 10. Conical hole; 11. Block; 12. Limiting tube; 13. Fixing block; 14. Vent hole; 15. First spring; 16. Pin hole; 17. Pin; 18. Second spring; 19. Groove; 20. Transparent observation window; 21. Connecting rod; 22. First magnetic ring; 23. Second magnetic ring; 24. Marking indicator ring; 25. Marking groove; 26. Baffle; 27. Ball bearing; 28. Limiting cap; 100. Box body. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] Please see Figures 1 to 9 A waterproof structure for use in cable branch boxes, comprising: A housing 1 is fixedly connected to the inner wall of the cable branch box 100. A hydrophobic and breathable membrane 2 is provided on one side of the housing 1, and a mesh plate 3 is provided on one side of the hydrophobic and breathable membrane 2. The mesh plate 3 is fixed to the housing 1 by bolts 4 to clamp and fix the hydrophobic and breathable membrane 2. The lower surface of the housing 1 is connected to a pipe 5, and the lower end of the pipe 5 passes through the cable branch box 100 and is connected to the outside of the cable branch box 100. A conical groove 6 is provided at one end of the pipe 5 located outside the cable branch box 100, and a water inlet sealing structure is provided in the conical groove 6; The water inlet sealing structure includes a float 7 disposed below the conical groove 6. The upper part of the float 7 has a conical structure that matches the conical groove 6. A limit slide rod 8 is fixedly connected to the upper surface of the float 7. The inner wall of pipe 5 is fixedly connected with an active sealing structure that can actively seal pipe 5.

[0022] As can be seen from the above structure: the shell 1 is fixed to the inner wall of the cable branch box 100, and the hydrophobic and breathable membrane 2 is clamped and fixed to one side of the shell 1 by the mesh plate 3 and bolts 4. The lower end of the pipe 5 connected to the lower surface of the shell 1 passes through the box 100 and is in communication with the outside atmosphere. The end of the pipe 5 located outside the box 100 is provided with a conical groove 6, and a float 7 is provided below the conical groove 6. The upper part of the float 7 has a conical structure that matches the conical groove 6, and a limiting slide rod 8 is fixedly connected to the upper surface of the float 7. When the box 100 produces a breathing effect due to the temperature difference between day and night, the internal and external gases can be exchanged through the hydrophobic and breathable membrane 2, while water vapor is blocked. When the external water level rises, the float 7 floats up and can initially seal the conical groove 6. The inner wall of pipe 5 is also fixed with an active sealing structure to increase the sealing performance of pipe 5; continuous moisture protection under the breathing effect is achieved through the hydrophobic and breathable membrane 2 to avoid the aging and failure of traditional sealing materials; at the same time, the basic interface of the passive sealing and active sealing structure driven by the float 7 is integrated to provide double waterproofing and improve the reliability of the cable branch box in humid or waterlogged environments.

[0023] Furthermore, the active sealing structure includes a sealing ring 9 fixed to the inner wall of the pipe 5. A conical hole 10 is formed on one side wall of the sealing ring 9, and a cone-shaped plug 11 is provided on one side of the conical hole 10. A limiting tube 12 is slidably connected to the inner wall of the plug 11, and a fixing block 13 with a vent hole 14 is fixedly connected to the outer wall of the limiting tube 12. The outer wall of the fixing block 13 is fixed to the inner wall of the pipe 5. A first spring 15 is provided on one side of the fixing block 13, and one end of the first spring 15 abuts against the plug 11. One end of the limiting slide rod 8 extends into the limiting tube 12, and a pin hole 16 is formed on the inner wall of the limiting tube 12. A fixing structure for limiting the plug 11 is provided in the pin hole 16. The active sealing structure includes a sealing ring 9 fixed to the inner wall of the pipe 5, and a conical hole 10 is formed on the sealing ring 9. A cone-shaped plug 11 is provided on one side of the conical hole 10, and the inner wall of the plug 11 is slidably connected to the limiting tube 12. The limiting tube 12 is fixed to the inner wall of the pipe 5 by a fixing block 13 with a vent hole 14. One end of the first spring 15 abuts against the fixing block 13, and the other end abuts against the plug 11, constantly pushing the plug 11 toward the conical hole 10. The upper end of the limiting slide rod 8 extends into the limiting tube 12. A pin hole 16 is provided on the inner wall of the limiting tube 12, and a fixing structure for limiting the plug 11 is provided in the pin hole 16. Under normal conditions, the fixing structure locks the plug 11, preventing it from sealing the conical hole 10; the first spring 15 can generate stable and continuous sealing pressure, which is superior to traditional gravity or buoyancy sealing.

[0024] Furthermore, the fixing structure includes a pin 17, one end of which passes through the pin hole 16 and extends to the side of the plug 11, while the other end of the pin 17 abuts against the limiting slide rod 8. A second spring 18 is fixedly connected to one side wall of the pin 17, one end of which is fixed to the pin hole 16. The outer wall of the limiting slide rod 8 has a fixing release structure. Specifically, the fixing structure is the pin 17. One end of the pin 17 passes through the pin hole 16 and extends below the plug 11, while the other end abuts against the limiting slide rod 8. One end of the second spring 18 is fixed to the pin hole 16, and the other end is fixed to the side wall of the pin 17, always pushing the pin 17 towards the limiting slide rod 8. The outer wall of the limiting slide rod 8 has a fixing release structure. Under normal operating conditions, the limiting slide bar 8 presses against the end of the pin 17, keeping the pin 17 locked in the position of the plug 11; when the limiting slide bar 8 moves to align the fixing release structure with the pin 17, the second spring 18 pushes the pin 17 into the fixing release structure, and the other end of the pin 17 disengages from the plug 11, releasing the plug 11.

[0025] Furthermore, the fixing and releasing structure includes a groove 19 formed in the side wall of the limiting slide bar 8. When float 7 moves upward, it drives limit slide 8 upward. When limit slide 8 moves upward to the point where the groove 19 is aligned with pin 17, the second spring 18 pushes pin 17 into the groove 19, causing pin 17 to disengage from the blockage 11. The first spring 15 pushes blockage 11 upward to seal conical hole 10. The fixing and releasing structure is groove 19, which is opened on the side wall of limit slide 8. When external water causes float 7 to float, float 7 drives limit slide 8 to move upward. When limit slide 8 rises to the position where groove 19 is aligned with pin 17, the second spring 18 pushes pin 17 into the groove 19, causing pin 17 to move laterally as a whole, and the end that is used to hold blockage 11 completely disengages from blockage 11. At this time, the first spring 15 releases its compression energy and pushes the plug 11 upward, so that the conical head of the plug 11 tightly seals the conical hole 10 on the sealing ring 9, thus achieving active sealing. The sealing action is rapid and reliable, and the sealing force is provided by the spring, which is stable over a long period of time.

[0026] Furthermore, an observation port is provided on the side wall of the cable branch box, and a transparent observation window 20 is fixedly connected to one side wall of the observation port; a connecting rod 21 is fixedly connected to one side wall of the plug 11, and a first magnetic ring 22 is fixedly connected to one end of the connecting rod 21; a second magnetic ring 23 is slidably fitted on the outer wall of the pipe 5, and a marking indicator ring 24 is fixedly fitted on the outer wall of the second magnetic ring 23; two marking grooves 25 are provided on the side wall of the transparent observation window 20, and the overlapping position of the marking indicator ring 24 with different marking grooves 25 is observed to determine whether the plug 11 has started sealing; the connecting rod 21 is fixed to the side wall of the plug 11, and the first magnetic ring 22 is fixed to the end of the connecting rod 21. The second magnetic ring 23 is slidably fitted on the outer wall of the pipe 5, and a marking indicator ring 24 is fixedly fitted on the outer wall of the second magnetic ring 23. Two marking grooves 25 at different heights are provided on the side wall of the transparent observation window 20. When the plug 11 moves up and down with the action, the first magnetic ring 22 drives the second magnetic ring 23 and the marking indicator ring 24 to move synchronously through magnetic coupling. When the indicator ring 24 coincides with the lower indicator groove 25, it indicates that the blockage 11 has not started sealing; when it coincides with the upper indicator groove 25, it indicates that the blockage 11 has sealed the cone hole 10. Maintenance personnel can make a direct judgment through the transparent observation window 20.

[0027] Furthermore, one end of the pin 17 has a groove, in which a ball bearing 27 is disposed, and the side wall of the ball bearing 27 contacts the limiting slide rod 8; the end of the pin 17 that contacts the limiting slide rod 8 also has a groove, in which the ball bearing 27 is disposed. The side wall of the ball bearing 27 makes rolling contact with the outer wall of the limiting slide rod 8. When the limiting slide rod 8 slides up and down, the ball bearing 27 rolls in the groove, converting the sliding friction between the pin 17 and the limiting slide rod 8 into rolling friction; reducing the frictional force between the pin 17 and the limiting slide rod 8, and ensuring smooth operation of the limiting slide rod 8.

[0028] Furthermore, one end of the limiting tube 12 is threadedly connected to a limiting cap 28, and the inner wall of the limiting cap 28 is slidably connected to the outer wall of the limiting slide rod 8; a baffle 26 is fixedly sleeved on the outer wall of the limiting slide rod 8 located above the limiting cap 28; the limiting tube 12 is threadedly connected to the limiting cap 28, and the inner wall of the limiting cap 28 is slidably engaged with the outer wall of the limiting slide rod 8, serving as a guide and radial limiting function. The baffle 26 fixedly sleeved on the outer wall of the limiting slide rod 8 located above the limiting cap 28 can restrict the limiting slide rod 8 and prevent it from falling off due to gravity.

[0029] Furthermore, the hydrophobic and breathable membrane 2 is a polymer waterproof and breathable membrane; the micropore diameter of this type of material is smaller than the particle size of water mist or liquid water, but larger than the diameter of air molecules. When there is a pressure difference between the inside and outside of the box 100, air molecules can freely pass through the membrane pores, while water vapor and water droplets are blocked on the outside of the membrane.

[0030] Furthermore, the float 7 is made of closed-cell foam plastic or a hollow sealed float; the material of float 7 is lightweight, non-absorbent, and corrosion-resistant, and can maintain stable buoyancy even after long-term immersion in water, ensuring reliable triggering of the active sealing structure under water accumulation conditions, and avoiding loss of waterproof function due to failure of float 7.

[0031] A cable branch box includes the aforementioned box body 100 and a waterproof structure.

[0032] In this invention, when the cable branch box 100 experiences a "breathing effect" due to the temperature difference between day and night, the internal air expands and contracts with temperature changes. It needs to exchange gas with the outside environment through the hydrophobic and breathable membrane 2 on the shell 1 to balance the pressure. The hydrophobic and breathable membrane 2 is clamped and fixed to one side of the shell 1 by the mesh plate 3 and bolts 4. Its micropore diameter is smaller than the water mist particle size but larger than the air molecule diameter, allowing air molecules to pass freely. Meanwhile, water vapor and liquid water in the humid outside air are effectively blocked outside the box 100, thus preventing condensation. At this time, the lower end of the pipe 5 is connected to the outside, the float 7 is in a downward position, the limiting slide rod 8 is located in the lower part of the limiting tube 12, and the pin 17, under the action of the second spring 18, abuts against the side wall of the limiting slide rod 8. Simultaneously, the other end of the pin 17 is stuck on one side of the blockage 11, overcoming the thrust of the first spring 15, keeping the blockage 11 separated from the conical hole 10 of the sealing ring 9. Gas can flow bidirectionally through the pipe 5, the vent 14, the shell 1, and the hydrophobic and breathable membrane 2. When water accumulates outside the cable branch box and the water level rises to submerge the lower end of pipe 5, float 7 moves upward under the action of buoyancy. The upper part of float 7 has a conical structure that matches the conical groove 6. After floating, it can first contact the conical groove 6 to form a preliminary passive seal, preventing a large amount of water from rushing directly into the lower end of pipe 5.

[0033] As the float 7 rises, it drives the limiting slide rod 8, which is fixedly connected to its upper surface, to move upward. The limiting slide rod 8 extends into the limiting tube 12, and its side wall has a groove 19. When the limiting slide rod 8 rises until the groove 19 is aligned with the pin 17, the second spring 18 pushes the pin 17 into the groove 19, causing the pin 17 to move laterally as a whole, and the end that was originally stuck on the plug 11 is completely disengaged from the plug 11. At this time, the compressed first spring 15 releases its energy, pushing the plug 11 to slide upward along the limiting tube 12. The conical head of the plug 11 is tightly inserted into the conical hole 10 on the sealing ring 9, achieving a conical seal and completely blocking the pipe 5. This active seal is provided with continuous sealing pressure by the first spring 15, which is reliable and stable. Even if the external water level drops or the float 7 falls back, the plug 11 remains blocked, preventing subsequent moisture or water from entering.

[0034] To ensure smooth operation, the contact end between pin 17 and limit slide bar 8 is provided with a groove and ball bearing 27 to convert sliding friction into rolling friction and reduce resistance. The limit cap 28 at the upper end of the limit tube 12 slides with the limit slide bar 8 to ensure motion guidance; When the blockage 11 is activated, the connecting rod 21 fixed to its side wall drives the first magnetic ring 22 to move synchronously. The first magnetic ring 22 and the second magnetic ring 23, which is slidably fitted on the outer wall of the pipe 5, are magnetically coupled. The second magnetic ring 23 and its external marking indicator ring 24 move up and down synchronously with the blockage 11. Maintenance personnel can observe the relative position of the marking indicator ring 24 and the two marking grooves 25 through the transparent observation window 20 on the side wall of the cable branch box: when the marking indicator ring 24 coincides with the lower marking groove 25, it indicates that the active seal has not yet been activated; when it coincides with the upper marking groove 25, it indicates that the blockage 11 has sealed the conical hole 10. The sealing status can be quickly determined without disassembling the equipment, which is convenient for daily inspection and maintenance.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended technical solutions and their equivalents.

Claims

1. A waterproof structure applied to a cable branch box, characterized in that, include: A housing (1) is fixedly connected to the inner wall of the cable branch box (100). A hydrophobic and breathable membrane (2) is provided on one side of the housing (1). A mesh plate (3) is provided on one side of the hydrophobic and breathable membrane (2). The mesh plate (3) is fixed to the housing (1) by bolts (4) to clamp and fix the hydrophobic and breathable membrane (2). The lower surface of the housing (1) is connected to a pipe (5), the lower end of the pipe (5) passes through the cable branch box (100) and is connected to the outside of the cable branch box (100); A conical groove (6) is provided at one end of the pipe (5) located outside the cable branch box (100), and a water inlet sealing structure is provided in the conical groove (6); The water inlet sealing structure includes a float (7) disposed below the conical groove (6). The upper part of the float (7) has a conical structure that matches the conical groove (6). A limit slide rod (8) is fixedly connected to the upper surface of the float (7). The inner wall of the pipe (5) is fixedly connected with an active sealing structure that can actively seal the pipe (5).

2. The waterproof structure according to claim 1, characterized in that, The active sealing structure includes a sealing ring (9) fixed to the inner wall of the pipe (5). A conical hole (10) is provided on one side wall of the sealing ring (9). A plug (11) with a conical end is provided on one side of the conical hole (10). A limiting tube (12) is slidably connected to the inner wall of the plug (11). A fixing block (13) with a vent hole (14) is fixedly connected to the outer wall of the limiting tube (12). The outer wall of the fixing block (13) is fixed to the inner wall of the pipe (5). A first spring (15) is provided on one side of the fixing block (13). One end of the first spring (15) abuts against the plug (11). One end of the limiting slide rod (8) extends into the inside of the limiting tube (12). A pin hole (16) is provided on the inner wall of the limiting tube (12). A fixing structure for limiting the plug (11) is provided in the pin hole (16).

3. The waterproof structure according to claim 2, characterized in that, The fixing structure includes a pin (17), one end of which passes through a pin hole (16) and extends to the side of the block (11), and the other end of which abuts against the limiting slide rod (8); a second spring (18) is fixedly connected to one side wall of the pin (17), one end of which is fixed to the pin hole (16), and the outer wall of the limiting slide rod (8) is provided with a fixing release structure.

4. The waterproof structure according to claim 3, characterized in that, The fixed release structure includes a groove (19) formed on the side wall of the limiting slide bar (8). When the float (7) moves upward, the float (7) drives the limiting slide (8) to move upward. When the limiting slide (8) moves upward to the point where the groove (19) is aligned with the pin (17), the second spring (18) pushes the pin (17) into the groove (19), causing the pin (17) to disengage from the limiting of the plug (11). The first spring (15) pushes the plug (11) upward to block the conical hole (10).

5. The waterproof structure according to claim 2, characterized in that, The cable branch box has an observation port on its side wall, and a transparent observation window (20) is fixedly connected to one side wall of the observation port; a connecting rod (21) is fixedly connected to one side wall of the blockage (11), and a first magnetic ring (22) is fixedly connected to one end of the connecting rod (21); a second magnetic ring (23) is slidably fitted on the outer wall of the pipe (5), and a marking indicator ring (24) is fixedly fitted on the outer wall of the second magnetic ring (23); two marking grooves (25) are opened on the side wall of the transparent observation window (20). By observing the overlapping position of the marking indicator ring (24) with different marking grooves (25), it is determined whether the blockage (11) has started to seal.

6. The waterproof structure according to claim 4, characterized in that, One end of the pin (17) is provided with a slot, and a ball (27) is provided in the slot. The side wall of the ball (27) is in contact with the limiting slide bar (8).

7. The waterproof structure according to claim 4, characterized in that, One end of the limiting tube (12) is threadedly connected to a limiting cap (28), and the inner wall of the limiting cap (28) is slidably connected to the outer wall of the limiting slide rod (8); a baffle (26) is fixedly sleeved on the outer wall of the limiting slide rod (8) located above the limiting cap (28).

8. The waterproof structure according to claim 1, characterized in that, The hydrophobic and breathable membrane (2) is a polymer waterproof and breathable membrane.

9. The waterproof structure according to claim 1, characterized in that, The float (7) is a closed-cell foam plastic or a hollow sealed float.

10. A cable branch box, characterized in that, It includes a housing (100) and a waterproof structure as described in any one of claims 1 to 9.

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