Moisture-proof cable branch box

Abstract

The application discloses a kind of dampproof cable branch box, it is related to the technical field of dampproof of power distribution equipment, including box, box is equipped with exhaust cylinder and air inlet, self-adapting dampproof valve box is fixedly installed in box, self-adapting dampproof valve box is communicated air inlet, self-adapting dampproof valve box is fixedly installed with locating plate inside, locating plate is penetrated and is equipped with cylindrical through-hole, high molecular humidity-sensitive expansion sealing core is movably arranged in cylindrical through-hole, elastic reset component is integratedly arranged in the bottom of cylindrical through-hole, and the bottom of high molecular humidity-sensitive expansion sealing core is abutted to elastic reset component, and linkage type sealing structure is matched and arranged above locating plate.The application achieves passive dampproof regulation and control effect of needing no power supply, no humidity sensor, no electric control execution element, relying on pure mechanical structure self-response environmental humidity change switches ventilation / closed state.

Description

Technical Field

[0001] This invention relates to the technical field of power distribution equipment, and in particular to a moisture-proof cable branch box. Background Technology

[0002] Cable distribution boxes are specialized distribution cabinets used for cable distribution, switching, and protection in power distribution networks. They are widely used in underground machine rooms, tunnel power distribution areas, and low-lying, damp outdoor areas. Cables operating continuously under energization generate humid and hot gases, and the damp environment easily causes corrosion of the internal terminals and aging of the insulation. Therefore, a moisture-proof structure is a core component for the safe operation of the distribution box. Conventional moisture-proof distribution boxes rely on ventilation or sealing structures to block moisture, thereby preventing leakage and short-circuit faults, and are suitable for the alternating dry and wet operating conditions caused by the intermittent start-stop of dehumidification equipment in underground machine rooms.

[0003] Currently, cable distribution box moisture-proof and ventilation structures fall into two basic categories: one is a permanently open ventilation structure, with fixed ventilation holes on the side wall of the cabinet to allow for air exchange between the inside and outside; the other is a permanently sealed cabinet, relying on sealing strips to completely isolate external air. An improved solution in the industry uses an electrically controlled ventilation valve paired with a humidity sensor. The sensor collects ambient humidity signals, and the electrical control circuit drives the electric valve to open and close the ventilation channel, adapting to changes in ambient humidity. This is currently the mainstream improvement technology for dealing with dry and humid environments.

[0004] In a permanently open ventilation structure, during the high-humidity phase when the dehumidifier is off, external high-humidity moisture will continuously enter the enclosure. Conversely, in a permanently sealed enclosure, during the drying phase when the dehumidifier is on, internal heat and moisture generated by the cables cannot be expelled. Neither of these fixed structures can adaptively switch between humidity states. Furthermore, electrically controlled moisture-proof structures rely on external power supply, sensors, and actuators. In damp underground environments, this can easily lead to sensor malfunctions, short circuits, and valve jamming, resulting in high maintenance costs and poor reliability. Current technologies lack adaptive moisture-proof valve structures that require no electricity or sensors and rely solely on purely mechanical structures to autonomously switch between ventilation and sealing states based on humidity. This makes them unsuitable for long-term moisture protection under intermittent wet-dry conditions. Summary of the Invention

[0005] This application provides a moisture-proof cable branch box that achieves passive moisture-proof control by autonomously switching between ventilated and sealed states in response to changes in ambient humidity, without the need for power supply, humidity sensors, or electronic control actuators, relying solely on a purely mechanical structure.

[0006] This application provides a moisture-proof cable branch box, which adopts the following technical solution: A moisture-proof cable branch box includes a box body with an exhaust duct and an air inlet. An adaptive moisture-proof valve box is fixedly installed inside the box body and is connected to the air inlet. A positioning plate is fixedly installed inside the adaptive moisture-proof valve box. The positioning plate has a through cylindrical hole. A polymer moisture-sensitive expansion sealing core is movably arranged inside the cylindrical hole. An elastic reset component is integrated at the bottom of the cylindrical hole and abuts against the bottom of the polymer moisture-sensitive expansion sealing core. A linkage sealing structure is matched above the positioning plate. The linkage sealing structure includes a sealing plug that matches the cylindrical hole. A magnetic linkage component is provided between the top of the polymer moisture-sensitive expansion sealing core and the bottom of the sealing plug.

[0007] Preferably, the adaptive moisture-proof valve box has an airflow inlet connected to the air inlet on the side wall near its bottom, and a horn-shaped airflow expansion outlet is provided on the top of the adaptive moisture-proof valve box. A multi-layer graded filter structure is fixedly installed inside the adaptive moisture-proof valve box along the airflow conveying path, and the mesh size of several sets of filters is set to decrease step by step along the upward airflow path inside the adaptive moisture-proof valve box.

[0008] Preferably, an annular locking ring is fitted inside the cylindrical through hole, the annular locking ring is fixedly embedded in the upper part of the cylindrical through hole, and the polymer moisture-sensitive expansion sealing core is movably arranged below the annular locking ring.

[0009] Preferably, the elastic reset component includes a cross-shaped support frame fixedly embedded in the bottom of the cylindrical through hole, and a first spring is fixedly connected between the central support point of the cross-shaped support frame and the bottom end of the polymer moisture-sensitive expansion sealing core.

[0010] Preferably, the linkage sealing structure further includes two sets of L-shaped positioning baffles symmetrically fixed to the inner sidewall of the adaptive moisture-proof valve box. The two sets of L-shaped positioning baffles are arranged opposite each other to form a vertical sliding track. A square frame is embedded inside the vertical sliding track. A second spring is fixedly connected between the square frame and the top of the two sets of L-shaped positioning baffles. A grid frame is integrally fixed inside the square frame. The sealing plug is vertically fixed at the bottom of the solid intersecting nodes of the grid frame.

[0011] Preferably, the magnetic linkage assembly includes a first magnetic block fixedly embedded at the center of the top of the polymer moisture-sensitive expansion sealing core, and a second magnetic block fixedly embedded at the center of the bottom of the sealing plug, wherein the polarities of the first magnetic block and the second magnetic block are matched.

[0012] Preferably, the exhaust duct is evenly distributed on the upper part of one side panel of the housing, the air inlet is opened on the lower part of the other side panel of the housing, and a dehumidification component is integrated inside the exhaust duct.

[0013] Preferably, all inner metal walls of the enclosure are fitted with a thin layer of high thermal conductivity heat storage liner, and the liner is fitted to the periphery of the electrical component installation area.

[0014] Preferably, an annular inclined condensation guide channel is provided on the inner side of the bottom of the box, so that all trace amounts of condensation remaining on the inner wall can flow into the sealed water collection cavity at the bottom of the guide channel along the wall surface.

[0015] Preferably, the bottom of the water collection cavity is attached to the ground outside the box, and heat-conducting metal fins are embedded inside the water collection cavity, the cross-section of which is a polygonal structure.

[0016] In summary, this application has the following beneficial effects: 1. In order to solve the core function of passively sensing ambient humidity and autonomously triggering the opening and closing of the channel, the present invention further optimizes the invention by setting a polymer humidity-sensitive expansion sealing core and a bottom elastic reset component inside the cylindrical through hole. This is used to achieve a passive sensing deformation effect of volume expansion and upward movement after water vapor adsorption and spring rebound reset after humidity decreases. The entire process can respond to changes in ambient humidity without the need for power sensing.

[0017] 2. To further optimize the function of the sealing plug misalignment and air leakage when the moisture-sensitive core expands, the present invention also sets up a magnetic linkage component respectively embedded at the top of the core and the bottom of the sealing plug. This component is used to achieve magnetic traction to accurately sink the sealing plug to seal the through hole during the upward movement of the core, eliminate minor alignment errors, and improve the sealing and moisture-proof effect under high humidity conditions.

[0018] 3. To further optimize the multi-channel synchronous sealing and sealing plug sliding jamming function, the present invention also sets up an L-shaped positioning baffle to form a vertical sliding track and a square frame grid structure connected with a second spring, which is used to realize the synchronous vertical lifting and lowering of multiple sets of sealing plugs, ensuring that all airflow channels are synchronously opened or blocked, and improving the consistency of opening and closing.

[0019] 4. To further optimize the function of preventing water vapor and impurities from clogging the precision valve body structure and shortening the equipment life, this invention also includes an adaptive moisture-proof valve box connected to the air inlet and a graded filter screen with progressively decreasing pore size inside. This is used to achieve gradient purification of the air entering the box, prevent water mist and dust from entering the precision linkage structure of the valve body, and avoid mechanical jamming failure.

[0020] 5. Through a purely mechanical, passive humidity-sensitive linkage structure, a breakthrough technological effect has been achieved in the industry, resolving the long-standing contradiction of moisture prevention in alternating dry and wet operating conditions. Specifically, this structure requires no power supply, no humidity sensor detection, and no electrically controlled valves. Relying on the humidity-sensitive deformation characteristics of polymer materials and the principles of mechanical elasticity and magnetic linkage, it achieves autonomous switching of operating conditions. The structure has extremely high stability, completely avoiding the failure risk of electrical control structures in humid environments, and significantly reducing equipment maintenance costs and failure rates. In addition, it can quickly seal off moisture in high humidity environments within milliseconds and conduct moisture outage instantly in low humidity environments, with no lag in operating condition switching, perfectly matching the periodic operating conditions of intermittent dehumidification in underground machine rooms. Moreover, it utilizes the slight heat generated by the working cable to create a slight pressure difference for active exhaust, eliminating the need for additional exhaust power components. Relying on the inherent operating characteristics of the equipment, it achieves energy-efficient and high-efficiency dehumidification without additional energy consumption, making it suitable for the long-term uninterrupted operation of power distribution equipment. Finally, the triple structure of graded gradient filtration, mechanical elastic reset, and magnetic precision sealing significantly improves the sealing and stability of the moisture-proof structure, effectively resisting the complex dust, water mist, and humid corrosive environment of the underground computer room. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the branch box in this invention; Figure 2 This is a schematic diagram of the overall internal structure of the branch box in this invention; Figure 3 This is a schematic diagram of the internal structure of the valve box in this invention; Figure 4 This is a schematic diagram of the overall connection structure between the positioning plate and the sealing structure in this invention; Figure 5 This is a partial cross-sectional view of the internal structure of the positioning plate in this invention; Explanation of reference numerals in the attached drawings: 1. Housing; 2. Exhaust duct; 3. Air inlet; 4. Valve box; 5. Filter screen; 6. Positioning plate; 7. Cylindrical through hole; 8. Polymer moisture-sensitive expansion sealing core; 9. Locking ring; 10. Miniature elastic reset component; 1001. Cross-shaped support frame; 1002. First spring; 11. Inlet; 12. Outlet; 13. Sealing structure; 1301. Positioning baffle; 1302. Square frame; 1303. Second spring; 1304. Grid frame; 1304. Sealing plug; 14. First magnetic block; 15. Second magnetic block; 16. Dehumidifier; 17. Liner; 18. Guide channel; 19. Water collection chamber; 20. Fin. Detailed Implementation

[0022] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0023] Example 1: This invention discloses a moisture-proof cable branch box, such as... Figure 1 As shown, Figure 1 and Figure 2 As shown, the enclosure includes a housing 1 and an integrated power cable assembly housed within the housing 1. The housing 1 provides a sealed protective space for cable operation, isolating it from external dust, rain, and debris, and providing a stable operating environment for internal moisture control and dehumidification. Several sets of exhaust ducts 2 are evenly distributed on the upper part of one side panel of the housing 1. All exhaust ducts 2 are equipped with integrated dehumidification components. The exhaust ducts 2 are centrally located in the upper part of the housing 1, conforming to the fluid dynamics principle of hot air rising, and can efficiently remove rising hot and humid air from the housing. A rectangular air inlet 3 is provided on the lower part of the other side panel of the housing 1, opposite to the exhaust ducts 2, forming a vertical convection ventilation duct with bottom inlet and top outlet. Driven by the built-in dehumidifier 16, external ambient air can flow into the housing 1 through the air inlet 3, pass through the entire cavity of the housing 1, and be discharged from the top exhaust duct 2, forming a continuous directional airflow circulation. This essentially achieves ventilation and dehumidification inside the housing 1, avoiding the problem of moisture retention in a static, sealed housing 1.

[0024] Figure 3 and Figure 4 As shown, to optimize the quality of the incoming airflow, block the intrusion of large particles of water vapor impurities, and achieve adaptive on / off control of the air inlet channel, an adaptive moisture-proof valve box 4 is fixedly installed inside the housing 1 and close to the air inlet 3. The valve box 4, as the core passive control component of this equipment, is the core structure for achieving adaptive switching between dry and wet conditions. The side wall of the valve box 4 near its bottom has an airflow inlet 11 that connects to the air inlet 3, ensuring that external airflow can be introduced into the valve box 4 without obstruction. The top of the valve box 4 is provided with a trumpet-shaped diffuser outlet 12, which is completely connected to the internal cavity of the housing 1. The diffuser structure of the trumpet can diffuse and guide the filtered and regulated dry airflow, avoiding concentrated impact of the incoming airflow on local cables, so that the dry air fills the interior of the housing 1 evenly and improves the overall dehumidification uniformity.

[0025] Figure 3 and Figure 4As shown, a multi-layered graded filter structure 5 is detachably and fixedly installed inside the valve box 4 along the airflow path. The mesh size of several sets of filter screens 5 is set in a progressively decreasing manner along the upward airflow path inside the valve box 4. This graded filtration structure has a gradient purification effect. The bottom layer of large-pore filter screen 5 can intercept suspended water mist, large particles of dust and impurities in the air. The middle layer of small-pore filter screen 5 can filter fine dust particles. The top layer of microporous filter screen 5 can accurately filter out trace amounts of water vapor condensation nuclei. Through multi-stage gradient filtration, the airflow entering the box is finely purified. On the one hand, it can effectively prevent external impurities from entering the box 1 and wearing down the cable equipment. On the other hand, it can prevent water vapor impurities from entering the subsequent sealing structure 13, preventing the precision mechanical structure from being blocked or jammed, and ensuring the long-term operational stability of the adaptive on / off structure.

[0026] Figure 4 and Figure 5 As shown, a rectangular positioning plate 6 is horizontally fixedly installed inside the valve box 4. The positioning plate 6 provides a stable installation reference for the subsequent sealing execution structure, reset structure and moisture-sensitive structure. Several cylindrical through holes 7 are evenly opened on the surface of the positioning plate 6. The cylindrical through holes 7 serve as the core channel for airflow inside the valve box 4. All cylindrical through holes 7 are fitted with an annular locking ring 9 and a polymer moisture-sensitive expansion sealing core 8. The annular locking ring 9 is fixedly embedded in the upper part of the cylindrical through hole 7, and the polymer moisture-sensitive expansion sealing core 8 is movably arranged below the locking ring 9. The locking ring 9 can limit the maximum upward displacement of the expansion core to prevent the core from over-expanding, falling off or shifting, and to ensure the positioning accuracy of the sealing structure 13.

[0027] Figure 4 and Figure 5 As shown, the polymer moisture-sensitive expansion sealing core 8 is made of a high-ratio moisture-sensitive expansion polymer composite material, possessing the characteristics of no power supply, no sensor, and purely physical water vapor response. The polymer moisture-sensitive expansion sealing core 8 is designed as an ellipsoidal structure, with its short-side cross-sectional dimension precisely set to half the cross-sectional dimension of the cylindrical through-hole 7. This dimensional design possesses strong structural adaptability and deformation redundancy, ensuring sufficient airflow clearance when the core has not absorbed water and expanded, guaranteeing smooth ventilation; and completely filling the internal space of the cylindrical through-hole 7 through volume expansion after the core absorbs water vapor, achieving complete channel sealing. Compared to the traditional cylindrical sealing structure 13, the ellipsoidal structure exhibits more uniform stress, a larger water vapor adsorption area, faster humidity response, and stronger deformation stability, effectively avoiding problems such as localized sealing failure and air leakage.

[0028] Figure 4 and Figure 5As shown, a miniature elastic reset component 10 is integrated into the bottom of the cylindrical through-hole 7. This miniature elastic reset component 10 serves as the power reset assembly for the humidity-sensitive sealing structure 13, enabling the sealing structure 13 to autonomously rebound and reset. The miniature elastic reset component 10 includes a cross-shaped support frame 1001 fixedly embedded in the bottom of the cylindrical through-hole 7. The cross-shaped support frame 1001 adopts a hollow structure design, which provides stable support for the elastic reset structure without obstructing the airflow channel, ensuring ventilation efficiency. A first spring 1002 is fixedly connected between the central support point of the cross-shaped support frame 1001 and the bottom of the polymer humidity-sensitive expansion sealing core 8. The first spring always maintains a slight pre-compression state, allowing it to conform to the bottom of the core in real time, providing stable elastic power for subsequent structural reset.

[0029] Figure 4 and Figure 5 As shown, a linkage sealing structure 13 is matched above the positioning plate 6, forming an on / off control assembly with the cylindrical through hole 7, the humidity-sensitive core, and the elastic reset component. The sealing structure 13 includes two sets of L-shaped positioning baffles 1301 symmetrically fixed to the inner sidewall of the valve box 4. The two sets of positioning baffles 1301 are arranged opposite each other to form a vertical sliding track. A square frame 1302 that can slide freely vertically is embedded inside the track. The side of the square frame 1302 matches the gap with the inner wall of the L-shaped positioning baffle 1301, and there is no jamming or offset during the sliding process. A second spring 1303 is fixedly connected between the square frame 1302 and the top of the positioning baffle 1301. The second spring 1303 provides elastic support and limit constraint for the downward sealing and upward reset of the square frame 1302.

[0030] Figure 4 and Figure 5 As shown, a grid frame 1304 is integrally fixed inside the square frame 1302. A columnar sealing plug 1304 is vertically fixed at the bottom of the intersecting nodes of the grid frame 1304. The outer diameter of the sealing plug 1304 precisely matches the inner diameter of the columnar through-hole 7, allowing it to completely fit against the inner wall of the through-hole for sealing. The hollow design of the grid frame 1304 maximizes the airflow area, ensuring airflow under ventilation conditions and preventing the sealing structure 13 from obstructing the air duct and causing poor ventilation. The concentrated arrangement of the sealing plugs 1304 at the intersecting nodes enables simultaneous sealing and conduction of multiple channels, ensuring the consistency of the overall structure's continuity.

[0031] Figure 4 and Figure 5As shown, to further improve the fitting accuracy and sealing stability of the sealing structure 13 and achieve precise linkage between moisture-sensitive deformation and mechanical seal, a first magnetic block 14 is fixedly embedded at the center of the top of the polymer moisture-sensitive expansion sealing core 8, and a second magnetic block 15 with a polarity matching the first magnetic block 14 is fixedly embedded at the center of the bottom of the sealing plug 1304. The two sets of magnetic blocks can achieve precise magnetic adsorption and alignment. During the process of the core absorbing water and expanding upward to block the channel, the magnetic adsorption can pull the sealing plug 1304 to precisely descend and embed into the cylindrical through hole 7, correcting the slight offset error during the mechanical sliding process, achieving high-precision fitting and sealing, completely eliminating the problem of air leakage and water seepage in micro-gap, and greatly improving the sealing and moisture-proof effect under high humidity conditions.

[0032] Figure 4 and Figure 5 As shown, this invention achieves an adaptive dynamic moisture-proof effect of high humidity sealing and low humidity ventilation and dehumidification in cable branch boxes through the above-mentioned purely mechanical passive linkage structure. It is perfectly adapted to the periodic dry and wet alternation working conditions of the dehumidification equipment in the underground machine room, which is intermittently started and stopped. Its core working principle is divided into two stages: high humidity sealing working condition and low humidity ventilation working condition. The entire process does not require electrical control, sensors, or manual intervention, and it can complete the working condition switching autonomously.

[0033] First, the high humidity shutdown and sealing operation: When the dehumidifier 16 in the computer room stops, the ambient humidity in the underground computer room rises rapidly, and the water vapor saturation continues to increase. When the ambient humidity reaches the critical threshold of the polymer moisture-sensitive expansion sealing core 8, the ellipsoidal moisture-sensitive core quickly adsorbs free water vapor and suspended water mist in the air, and its own volume undergoes a multiplier-like physical expansion. During the expansion process, the core overcomes the preload force of the first spring and moves upward. At the same time, through the magnetic attraction linkage between the top magnetic block and the bottom magnetic block of the sealing plug 1304, the sealing plug 1304 is pulled down precisely along the track of the positioning baffle 1301 and completely embedded inside the cylindrical through hole 7. At this time, the multi-stage structure locks synchronously, the airflow channel inside the valve box 4 is completely blocked, and the box 1 forms a fully sealed protective structure, which can completely block the intrusion of external high humidity air and suspended water mist into the box 1, fundamentally solving the industry problem of external water vapor backflow and box 1 becoming damp and condensing during the high humidity stage when the dehumidifier 16 stops. The locking ring 9's limiting design prevents excessive expansion and displacement of the core, ensuring consistent accuracy in each sealing and plugging operation, and achieving long-term stable airtight protection.

[0034] Second, low humidity start-up ventilation condition: When the dehumidifier 16 in the computer room starts working, the water vapor in the ambient air is quickly extracted and purified, and the ambient humidity continues to decrease gradually. The ambient humidity where the polymer moisture-sensitive expansion sealing core 8 is located is lower than the critical response threshold. The water vapor adsorbed inside the core quickly dehydrates and evaporates, and the volume continues to shrink and reset. The first spring, which was originally compressed by the expansion of the core, instantly releases its elastic potential energy and rebounds upward to lift the moisture-sensitive core. At the same time, the magnetic attraction gradually dissipates as the core separates from the sealing plug 1304. The second spring 1303 drives the square frame 1302 and the sealing plug 1304 to move upward and reset. The airflow channel of the cylindrical through hole 7 is fully open, and the valve box 4 returns to the ventilation state.

[0035] Under ventilation conditions, the continuous operation of the cable generates stable micro-heat, causing the air temperature inside enclosure 1 to be slightly higher than the ambient air temperature. The heated air expands, creating a small positive pressure difference. Utilizing the bottom-in, top-out directional air duct, the accumulated humid and hot air and trace amounts of condensate inside enclosure 1 are actively guided out through exhaust duct 2, achieving active dehumidification and drying inside enclosure 1. Simultaneously, the multi-stage gradient filter 5 inside valve box 4 continuously purifies and filters the incoming fresh air, ensuring that the air entering enclosure 1 is dry and clean, forming a virtuous cycle of "fresh air filtered into the enclosure, and active exhaust of humid and hot air."

[0036] In Example 2, during the dehumidifier 16's shutdown and resting phase, the adaptive moisture-proof ventilation channel of this invention is in a normally open ventilation state, which can effectively release the accumulated moisture inside the box. However, this also results in a certain proportion of humid and hot air remaining inside the box 1. When the dehumidifier 16 starts operating instantaneously, the overall humidity of the machine room will drop rapidly in a short period of time. The moisture-sensitive sealing structure 13 can respond quickly to the change in ambient humidity and immediately close the ventilation channel of the box 1, effectively isolating the box 1 from the external low-humidity environment and preventing external dry airflow disturbances and water vapor intrusion. However, during the transient process of switching operating conditions, the residual humid and hot air sealed inside the box 1 cannot be discharged instantly and continues to be in full contact with the inner wall of the low-temperature metal box 1. The metal cabinet has the physical characteristics of high thermal conductivity and rapid temperature change. The temperature of the inner wall drops rapidly with the room environment, causing the temperature of the humid and hot air inside the box to drop rapidly below the dew point temperature. Water vapor undergoes a phase change and condenses, generating fine condensation droplets on a large area of ​​the inner wall of the box 1.

[0037] The generated fine condensation droplets slowly slide and spread along the inner metal wall, continuously adhering to the surfaces of core electrical components such as wiring terminals, busbars, and cable insulation layers inside the enclosure. Under the long-term cyclical conditions of alternating dry and wet, hot and cold environments in the computer room, condensation repeatedly condenses, accumulates, and undergoes minute evaporation. Over time, this accumulation can trigger a series of equipment failures: metal wiring terminals and busbars experience electrochemical oxidation and corrosion, leading to increased contact resistance and intensified heat generation; cable insulation layers, constantly damp, soften, age, and crack, resulting in a continuous decline in insulation strength and significantly increasing the risk of major safety failures such as leakage, creepage, and phase-to-phase short circuits during equipment operation. Therefore, traditional single-adaptive ventilation and moisture-proof structures can only solve the problem of moisture protection during steady-state alternating dry and wet conditions, completely failing to cover the low-temperature secondary condensation protection scenario during the transition between intermittent dehumidification conditions, creating a blind spot in protection for critical operating conditions.

[0038] like Figure 2 As shown, all inner metal walls of enclosure 1 are covered with a thin layer of high thermal conductivity heat storage liner 17. The liner 17 fully covers the inner areas of the side walls, top walls, and bottom walls of enclosure 1, and focuses on covering the outer perimeter of the installation areas of core electrical components such as busbars, terminals, and cable joints inside the enclosure. Relying on the special material properties of high thermal conductivity, high heat storage, and low temperature decay, the liner 17 can continuously collect and store the micro-joule residual heat generated by the long-term stable operation of the cables. Through the physical principle of passive heat storage and voltage stabilization, it effectively buffers and weakens the instantaneous temperature difference between the inner wall of enclosure 1 and the internal humid and hot air, completely eliminating the core cause of condensation due to cooling of the metal cold walls, inhibiting the dew point phase change of humid and hot air from the source, and significantly reducing the probability of transient condensation.

[0039] like Figure 2 As shown, the bottom inner side of the housing 1 is integrally formed with an annular inclined condensation guide channel 18. The guide channel 18 adopts a converging inclined structure with high edges and a low center. The slope optimized by fluid dynamics can realize the rapid convergence of trace water droplets, ensuring that the very small amount of fine condensation and atomized water droplets remaining on the inner wall of the housing 1 can slide down the wall surface quickly and smoothly into the sealed water collection cavity 19 integrated at the bottom of the guide channel 18, realizing the directional collection and centralized storage of condensation. The sealed water collection cavity 19 adopts a closed structure design, with only the top connected to the guide channel 18, which can effectively prevent the secondary evaporation and backflow of collected water into the inner cavity of the housing 1, completely eliminating the secondary diffusion and pollution of water vapor, and preventing residual moisture from corroding electrical equipment again.

[0040] like Figure 2As shown, the bottom of the water collection chamber 19 is attached to the ground outside the box 1, ensuring stable contact with the ambient temperature of the computer room. Embedded and fixedly installed inside the water collection chamber 19 are zigzag-shaped heat-conducting metal fins 20. Compared to the traditional straight fin structure 20, the zigzag cross-section structure significantly improves the heat-conducting contact area and heat exchange efficiency, exhibiting excellent passive heat storage, heat conduction, and evaporation performance. These heat-conducting metal fins 20 enable all-weather passive heat energy utilization, actively absorbing waste heat from the computer room environment during the day and continuously storing the working waste heat generated by the uninterrupted operation of cable equipment at night. Relying on pure passive heat conduction and thermal radiation, the fins continuously and gently heat the trace amounts of condensate collected inside the water collection chamber 19, achieving slow, stable, and autonomous evaporation and absorption of the condensate. The evaporated trace amounts of water vapor can naturally dissipate with the overall ventilation airflow of the room, requiring no manual drainage, no power drive, and no electrical control intervention, completely achieving passive zeroing of condensate and long-term prevention of sedimentation.

[0041] Working principle: First, this solution relies on the lower air inlets 3 on both sides of the box 1 and the upper exhaust duct 2 to form a convection air duct with lower inlet and upper outlet. The air inlet 3 inside the box 1 is fixedly connected to the adaptive moisture-proof valve box 4. The positioning plate 6 inside the valve box 4 has multiple sets of cylindrical through holes 7 as the core airflow channel. The entire valve body relies on the high-polymer moisture-sensitive material and mechanical elasticity and magnetic attraction structure to achieve passive adaptive control. The whole system is divided into two working condition logics: high humidity sealing and low humidity ventilation.

[0042] Then, the high humidity shutdown and sealing process begins. Once the dehumidifier 16 in the underground machine room stops working, the ambient air humidity rises rapidly. Free water vapor in the air is quickly adsorbed by the polymer moisture-sensitive expansion sealing core 8 inside the cylindrical through-hole 7. Subsequently, the core undergoes a multiplier-like volume expansion, pressing down on the bottom first spring 1002 and displacing upwards. The annular locking ring 9 limits the maximum upward stroke of the core to prevent structural detachment and displacement. At the same time, the first magnetic block 14 at the top of the core moves upwards, relying on magnetic attraction to pull the second magnetic block 15 at the bottom of the sealing plug 1304, causing the grid frame 1304 and the square frame 1302 to slide downwards along the vertical track formed by the L-shaped positioning baffle 1301. The second spring 1303 is simultaneously stretched and stores energy. Finally, the sealing plug 1304 is completely embedded in the cylindrical through-hole 7, all airflow channels are simultaneously blocked, the valve box 4 blocks the entry of external high humidity air into the cabinet 1, and the cabinet forms a sealed space, preventing external water vapor from flowing back and condensing.

[0043] Next, the system switches to low-humidity start-up and ventilation mode. First, the dehumidifier 16 in the computer room starts and removes moisture from the air, causing the ambient humidity to drop continuously. The moisture adsorbed by the polymer moisture-sensitive expansion sealing core 8 gradually evaporates, and its volume continues to shrink. Then, the first spring 1002, which was originally compressed, releases its elastic potential energy, pushing the moisture-sensitive core upward. The two sets of magnetic blocks gradually separate as the core moves downward, and the magnetic attraction force disappears. Subsequently, the second spring 1303 contracts and rebounds, pulling the square frame 1302, the grid frame 1304, and the sealing plug 1304 upward along the track. The sealing plug 1304 completely detaches from the cylindrical through hole 7, and all airflow channels are restored to conduction. At the same time, the multi-layer graded filter screen 5 in the valve box 4 continuously filters the incoming air step by step, removing water mist, dust impurities, and clean and dry airflow enters the interior of the box 1 through the through hole and the funnel-shaped expansion outlet 12. Finally, the cable is energized and generates a small amount of heat, which creates a small positive pressure difference in the air inside the box. The hot and humid air continues to rise and is discharged from the exhaust duct 2 at the top of the box 1, forming a stable ventilation and dehumidification cycle, automatically dissipating the accumulated moisture inside, and completing the autonomous dehumidification work in a low-humidity environment.

[0044] The entire workflow is completely free of electrical control components, power supply lines, and humidity sensors. It automatically switches between working conditions by relying on the physical deformation of materials and mechanical linkage structure. It can adapt to the alternating dry and wet environment caused by the periodic start and stop of dehumidification equipment in underground computer rooms around the clock, and can maintain the moisture-proof protection of the cabinet for a long time without manual intervention.

[0045] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A moisture-proof cable branch box, characterized in that, The device includes a housing (1), on which an exhaust duct (2) and an air inlet (3) are provided. A valve box (4) is fixedly installed inside the housing (1). The valve box (4) is connected to the air inlet (3). A positioning plate (6) is fixedly installed inside the valve box (4). A cylindrical through hole (7) is opened through the positioning plate (6). A polymer moisture-sensitive expansion sealing core (8) is movably arranged inside the cylindrical through hole (7). An elastic reset component is integrated at the bottom of the cylindrical through hole (7). The elastic reset component abuts against the bottom of the polymer moisture-sensitive expansion sealing core (8). A linkage sealing structure (13) is matched above the positioning plate (6). The linkage sealing structure (13) includes a sealing plug (1304) that matches the cylindrical through hole (7). A magnetic linkage component is provided between the top of the polymer moisture-sensitive expansion sealing core (8) and the bottom of the sealing plug (1304).

2. The moisture-proof cable branch box according to claim 1, characterized in that, The valve box (4) has an airflow inlet (11) connected to the air inlet (3) on its side wall near its bottom. The valve box (4) has a horn-shaped expansion outlet (12) at its top. The valve box (4) has a multi-layer graded filter screen (5) structure fixedly installed inside along the airflow conveying path. The mesh size of several sets of filter screens (5) is set to decrease step by step along the upward airflow path inside the valve box (4).

3. The moisture-proof cable branch box according to claim 1, characterized in that, The cylindrical through hole (7) is fitted with an annular locking ring (9), which is fixedly embedded in the upper part of the cylindrical through hole (7), and the polymer moisture-sensitive expansion sealing core (8) is movably arranged below the annular locking ring (9).

4. The moisture-proof cable branch box according to claim 1, characterized in that, The elastic reset component includes a cross-shaped support frame (1001) fixedly embedded in the bottom of the cylindrical through hole (7), and a first spring (1002) is fixedly connected between the central support point of the cross-shaped support frame (1001) and the bottom end of the polymer moisture-sensitive expansion sealing core (8).

5. The moisture-proof cable branch box according to claim 1, characterized in that, The linkage sealing structure (13) also includes two sets of positioning baffles (1301) symmetrically fixed to the inner side wall of the valve box (4). The two sets of positioning baffles (1301) are arranged opposite each other to form a vertical sliding track. A square frame (1302) is embedded inside the vertical sliding track. A second spring (1303) is fixedly connected between the square frame (1302) and the top of the two sets of positioning baffles (1301). A grid frame (1304) is integrally fixed inside the square frame (1302). The sealing plug (1304) is vertically fixed at the bottom of the solid intersecting nodes of the grid frame (1304).

6. The moisture-proof cable branch box according to claim 1, characterized in that, The magnetic linkage assembly includes a first magnetic block (14) fixedly embedded at the center of the top of the polymer moisture-sensitive expansion sealing core (8), and a second magnetic block (15) fixedly embedded at the center of the bottom of the sealing plug (1304). The first magnetic block (14) and the second magnetic block (15) have matching polarities.

7. The moisture-proof cable branch box according to claim 1, characterized in that, The exhaust duct (2) is evenly distributed on the upper part of one side panel of the box (1), the air inlet (3) is opened on the lower part of the other side panel of the box (1), and a dehumidification component is integrated inside the exhaust duct (2).

8. The moisture-proof cable branch box according to claim 1, characterized in that, The inner metal walls of the enclosure (1) are fitted with thin-layer high thermal conductivity heat storage lining (17), and the lining (17) is fitted to the periphery of the electrical component installation area.

9. The moisture-proof cable branch box according to claim 8, characterized in that, The bottom inner side of the box (1) is provided with an annular inclined condensation guide channel (18), and all the residual trace condensation on the inner wall can flow into the sealed water collection cavity (19) at the bottom of the guide channel (18) along the wall surface.

10. The moisture-proof cable branch box according to claim 9, characterized in that, The bottom of the water collection cavity (19) is attached to the ground outside the box body (1), and the interior of the water collection cavity (19) is embedded with heat-conducting metal fins (20), the cross section of which is a broken line structure.

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