Low voltage fire resistant insulated power cable

Abstract

The application discloses a low-voltage fireproof insulation power cable and relates to the technical field of fireproof insulation of power cables. The application is characterized in that a multi-ring cavity structure composed of radial partition ribs and annular connecting ribs is arranged in a fire-retardant assembly, and different annular cavities are filled with expanded graphite, aerogel particles and microencapsulated foaming agents respectively, so that the cable can form an expanded carbonized heat insulation layer, a low-thermal-conductivity heat insulation layer and a gas-producing foaming and combustion-suppressing layer in sequence when heated, and realize multi-stage progressive fire-retardant protection. Meanwhile, the pressure trigger pressure relief structure composed of a gas-permeable groove and a plug can realize directional release and pressure control adjustment when the internal gas pressure rises, thereby effectively inhibiting flame spread, delaying heat transfer and improving structural stability, so that the cable as a whole has excellent fireproof safety performance and thermal failure protection capability.

Description

Technical Field

[0001] This invention relates to the field of fireproof insulation technology for power cables, specifically a low-voltage fireproof insulated power cable. Background Technology

[0002] With the continuous development of power systems, low-voltage power cables are increasingly widely used in buildings, power transmission, and industrial equipment. Existing low-voltage power cables typically employ a basic structure of conductor, insulation layer, and outer sheath. Some products enhance fire resistance by adding flame-retardant materials or a single filler layer outside the insulation layer. However, existing fire-resistant cables still have the following problems: On the one hand, the flame-retardant structure of traditional cables is mostly a single layer or uniform filling structure, lacking graded flame-retardant design. In high temperature or fire environments, heat is easily transferred rapidly along the radial direction, causing the internal insulation layer to fail quickly, which in turn leads to short circuits or electrical faults. On the other hand, existing flame-retardant materials have single functions, usually only having heat absorption or flame-retardant effects, making it difficult to achieve multiple functions such as heat insulation, flame suppression and structural protection at the same time, resulting in limited fire resistance.

[0003] Furthermore, existing cables are prone to internal gas accumulation during heating, lacking effective pressure release and conduit structures, which can easily cause localized bulging or even sheath rupture, thereby accelerating fire spread and reducing overall safety. Therefore, there is an urgent need for a low-voltage fire-resistant insulated power cable with a graded flame-retardant structure, thermal insulation capabilities, and pressure regulation capabilities. Summary of the Invention

[0004] To address the technical problems of insufficient flexibility, internal stress concentration, easy fatigue damage, and short service life of existing power cables used in robots and cable carrier systems during long-term bending and reciprocating motion, this invention provides a low-voltage fire-resistant insulated power cable.

[0005] The technical solutions provided by the embodiments of the present invention are as follows: This invention provides a low-voltage fire-resistant insulated power cable, comprising: a cable core assembly, a filling layer, a flame-retardant assembly, and an outer sheath layer; The cable core assembly includes a conductor core, an insulation layer covering the outside of the conductor core, and a fire-resistant mica tape layer. The filler layer is disposed between the cable core assembly and the flame-retardant assembly; The flame-retardant component includes radial partition ribs and annular connecting ribs, which together form at least three annular cavities arranged radially in sequence. The annular cavities include a first annular cavity, a second annular cavity, and a third annular cavity. The first circumferential cavity is filled with expanded graphite, the second circumferential cavity is filled with aerogel particles, and the third circumferential cavity is filled with microencapsulated foaming agent. The outer sheath covers the outside of the flame-retardant component and has an air guide groove on its inner side.

[0006] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: This invention utilizes a multi-circular cavity structure composed of radial dividing ribs and annular connecting ribs within the flame-retardant component. Expanded graphite, aerogel particles, and microencapsulated foaming agents are filled into different circumferential cavities, allowing the cable to sequentially form an expanded carbonized heat insulation layer, a low thermal conductivity heat insulation layer, and a gas-generating foaming flame-suppressing layer when heated, achieving multi-level progressive flame-retardant protection. Simultaneously, a pressure-triggered pressure relief structure composed of venting grooves and plugs enables directional release and pressure control when internal gas pressure increases, effectively suppressing flame spread, delaying heat transfer, and improving structural stability. This results in the cable possessing excellent fire safety performance and thermal failure protection capabilities. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a schematic diagram of the overall structure of a low-voltage fireproof insulated power cable provided in an embodiment of the present invention.

[0009] Figure 2 This is a schematic diagram of the internal structure of a low-voltage fireproof insulated power cable provided in an embodiment of the present invention.

[0010] Figure 3 This is a schematic diagram of the cross-sectional structure of a low-voltage fireproof insulated power cable provided in an embodiment of the present invention.

[0011] Figure 4 This is a schematic diagram of the overall structure of a plug for a low-voltage fireproof insulated power cable, provided as an embodiment of the present invention.

[0012] Reference numerals: 1. Cable core assembly; 101. Conductor core; 102. Insulation layer; 103. Fire-retardant mica tape layer; 2. Filler layer; 3. Flame-retardant assembly; 301. Radial separator; 302. Annular connecting rib; 303. First circumferential cavity; 304. Second circumferential cavity; 305. Third circumferential cavity; 306. Expanded graphite; 307. Aerogel particles; 308. Microencapsulated foaming agent; 309. Partition; 310. Ventilation groove; 311. Plug; 312. Limiting groove; 4. Outer sheath layer; 401. Air guide groove.

[0013] As shown in the figure, specific structures and devices are marked in the figure to clearly illustrate the structure of the embodiments of the present invention. However, this is only for illustrative purposes and is not intended to limit the present invention to this specific structure, device and environment. Those skilled in the art can adjust or modify these devices and environments according to specific needs. Detailed Implementation

[0014] The technical solutions of the present invention will now be described with reference to the accompanying drawings. It should be noted that, to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art can use other alternative methods to implement some well-known technologies. Furthermore, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0015] like Figures 1 to 4 As shown, an embodiment of the present invention provides a low-voltage fire-resistant insulated power cable, comprising: a cable core assembly 1, a filling layer 2, a flame-retardant assembly 3, and an outer sheath layer 4; The cable core assembly 1 includes a conductor core 101, an insulation layer 102 covering the outside of the conductor core 101, and a fireproof mica tape layer 103; Filler layer 2 is disposed between cable core assembly 1 and flame retardant assembly 3; The flame-retardant component 3 includes radial partition ribs 301 and annular connecting ribs 302. The radial partition ribs 301 and annular connecting ribs 302 enclose and form at least three annular cavities arranged in sequence along the radial direction. The annular cavities include a first annular cavity 303, a second annular cavity 304 and a third annular cavity 305. The first circumferential cavity 303 is filled with expanded graphite 306, the second circumferential cavity 304 is filled with aerogel particles 307, and the third circumferential cavity 305 is filled with microencapsulated foaming agent 308. The outer sheath layer 4 covers the outside of the flame-retardant component 3, and an air guide groove 401 is provided on its inner side.

[0016] A partition 309 is provided between the radial partition 301 and the annular connecting rib 302 to physically isolate adjacent circumferential cavities.

[0017] It should be noted that the filler layer 2 is used to form a flexible thermal insulation buffer zone between the cable core assembly 1 and the flame-retardant assembly 3, and to absorb and disperse radial thermal stress in order to reduce the rate at which heat is directly transferred to the flame-retardant assembly 3.

[0018] The radial dividing ribs 301 are distributed radially and together with the annular connecting ribs 302 form a multi-layer annular closed cavity structure.

[0019] It should be noted that the multi-layered annular closed cavity structure is used to form a radial gradient thermal resistance path, so that heat undergoes multiple refractions and blockages during radial propagation, thereby extending the heat transfer path and reducing the heat diffusion rate.

[0020] Aerogel particles 307 within the second circumferential cavity 304 are used to form a low thermal conductivity insulation layer to reduce the rate of heat transfer to the inner layer.

[0021] It should be noted that the aerogel particles 307 form a stable nanoporous structure under heating conditions, which is used to suppress air convection and reduce the thermal conductivity, thereby achieving a long-term heat insulation effect.

[0022] The expanded graphite 306 in the first circumferential cavity 303 expands under heating conditions and forms a carbonized heat insulation structure.

[0023] It should be noted that expanded graphite 306 expands rapidly under heating conditions and forms a porous carbon layer structure. This carbon layer structure has high thermal resistance and self-supporting properties, which are used to block the spread of external flames inward.

[0024] The microencapsulated foaming agent 308 in the third circumferential cavity 305 decomposes under heating conditions, releasing inert gas and forming a foamed heat insulation layer.

[0025] It should be noted that the microencapsulated foaming agent 308 ruptures its shell and releases inert gas under heating conditions, while simultaneously forming a foam layer with low density and high volume expansion ratio to reduce oxygen concentration and weaken the intensity of combustion reaction.

[0026] A venting groove 310 is provided inside the annular connecting rib to form a gas discharge channel when the pressure in the third annular cavity 305 increases, so as to release the gas generated by thermal decomposition.

[0027] It should be noted that the venting groove 310 is used to form a directional pressure relief path when the gas pressure inside the cavity reaches a preset threshold, so as to realize unidirectional gas discharge and avoid structural damage caused by overpressure inside the cavity.

[0028] A stopper 311 is movably disposed inside the venting groove 310. Under the action of elastic restoring force at room temperature, the stopper 311 seals the venting groove 310. When the gas pressure increases due to the thermal decomposition of the microencapsulated foaming agent 308 in the third circumferential cavity 305, the stopper 311 is pushed open by the gas pressure, so that the venting groove 310 is open.

[0029] It should be noted that the plug 311 is displaced along a preset direction under the action of heated gas pressure, and the vent groove 310 is opened by elastic deformation or detachment, thereby realizing the pressure-triggered pressure relief control mechanism.

[0030] The annular connecting rib is provided with several limiting grooves 312. The limiting grooves 312 cooperate with the plug 311 to limit the displacement range of the plug 311 in the unheated state, and guide the plug 311 to directionally detach from the vent groove 310 under the action of gas pressure.

[0031] It should be noted that the limiting groove 312 is used to position and constrain the plug 311 in the non-working state, and guide the plug 311 to undergo directional displacement along a predetermined path under the action of gas pressure, so as to improve the opening reliability.

[0032] When heated, the first annular cavity 303, the second annular cavity 304, and the third annular cavity 305 sequentially trigger expansion, heat insulation, and gas generation reactions to form a tiered flame-retardant protection system.

[0033] It should be noted that the first circumferential cavity 303, the second circumferential cavity 304 and the third circumferential cavity 305 work together through the functional gradient of materials and structural barriers, so that the system sequentially triggers expansion flame retardancy, heat insulation delay and gas generation and pressure relief reaction under heating conditions, thereby forming a progressive multi-level fire protection mechanism.

[0034] The overall working principle of this invention is as follows: Under normal operating conditions, the low-voltage fireproof insulated power cable of the invention has an insulation layer 102 and a fireproof mica tape layer 103 sequentially arranged outside the conductor core 101 to achieve basic electrical insulation and conventional temperature resistance protection. The cable exterior is composed of a filling layer 2, a flame-retardant component 3, and an outer sheath layer 4, forming a multi-layer protective structure. The flame-retardant component 3 is formed by radially separating ribs 301 and annular connecting ribs 302, forming a three-layer radially progressive closed cavity structure of a first annular cavity 303, a second annular cavity 304, and a third annular cavity 305, which are respectively filled with expanded graphite 306, aerogel particles 307, and microencapsulated foaming agent 308 to form a gradient flame-retardant system.

[0035] When the cable is in a fire or high-temperature environment, the external heat first acts on the outer sheath layer 4 and gradually transfers inward. In the initial stage of heating, the microencapsulated foaming agent 308 in the third circumferential cavity 305 decomposes under heat, releases inert gas and forms an expanding foam structure. At the same time, the internal pressure of the third circumferential cavity 305 increases. The pressure acts on the plug 311 in the venting groove 310. When the pressure reaches the preset threshold, the plug 311 is guided to move along the limiting groove 312 under the action of gas thrust, thereby opening the venting groove 310. The outer sheath layer 4 is limited, thereby realizing directional pressure relief and gas discharge. The gas is discharged through the gas guiding groove 401 in the outer sheath layer 4, thereby reducing the local oxygen concentration and inhibiting the continued combustion of the flame.

[0036] As the temperature rises further, the aerogel particles 307 in the second circumferential cavity 304 form a low thermal conductivity insulation barrier, effectively blocking the transfer of heat to the inner layer and slowing down the internal temperature rise rate. At the same time, the expanded graphite 306 in the first circumferential cavity 303 expands in volume when heated and forms a dense carbonized insulation layer, which covers and protects the conductor core 101 and prevents high temperature from directly penetrating.

[0037] In the above process, the multi-cavity structure formed by the radial dividing rib 301 and the annular connecting rib 302, together with the partition 309, can block the heat propagation path multiple times, changing the heat conduction path from continuous transmission to a multi-segmented intermittent transmission state, thereby significantly reducing the heat diffusion efficiency. At the same time, the pressure-triggered opening mechanism of the plug 311 realizes the directional release and pressure relief control of the gas inside the cavity, avoiding excessive internal pressure that could lead to structural damage.

[0038] Ultimately, this invention achieves coordinated control of multiple factors such as heat, gas, and pressure through a three-stage progressive mechanism: gas generation and flame suppression in the third circumferential cavity 305, heat insulation and delay in the second circumferential cavity 304, and carbonization protection in the first circumferential cavity 303. This effectively improves the flame retardant performance, structural stability, and insulation reliability of cables in fire environments.

[0039] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the preferred embodiments, while those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0040] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-voltage fire-resistant insulated power cable, characterized in that, include: Cable core assembly, filler layer, flame retardant assembly, and outer sheath layer; The cable core assembly includes a conductor core, an insulation layer covering the outside of the conductor core, and a fire-resistant mica tape layer. The filler layer is disposed between the cable core assembly and the flame-retardant assembly; The flame-retardant component includes radial partition ribs and annular connecting ribs, which together form at least three annular cavities arranged radially in sequence. The annular cavities include a first annular cavity, a second annular cavity, and a third annular cavity. The first circumferential cavity is filled with expanded graphite, the second circumferential cavity is filled with aerogel particles, and the third circumferential cavity is filled with microencapsulated foaming agent. The outer sheath covers the outside of the flame-retardant component and has an air guide groove on its inner side.

2. The low-voltage fire-resistant insulated power cable according to claim 1, characterized in that: A partition is provided between the radial dividing rib and the annular connecting rib to physically isolate adjacent circumferential cavities.

3. A low-voltage fire-resistant insulated power cable according to claim 1, characterized in that: The radial dividing ribs are distributed radially and together with the annular connecting ribs, they form a multi-layered annular closed cavity structure.

4. A low-voltage fire-resistant insulated power cable according to claim 1, characterized in that: The aerogel particles in the second circumferential cavity are used to form a low thermal conductivity insulation layer to reduce the rate of heat transfer to the inner layer.

5. A low-voltage fire-resistant insulated power cable according to claim 1, characterized in that: The expanded graphite in the first circumferential cavity expands under heating conditions and forms a carbonized heat-insulating structure.

6. A low-voltage fire-resistant insulated power cable according to claim 1, characterized in that: The microencapsulated foaming agent in the third circumferential cavity decomposes and releases inert gas under heating conditions, forming a foamed heat insulation layer.

7. A low-voltage fire-resistant insulated power cable according to claim 1, characterized in that: The annular connecting rib is provided with a venting groove, which is used to form a gas discharge channel when the pressure in the third annular cavity increases, so as to release the gas generated by thermal decomposition.

8. A low-voltage fire-resistant insulated power cable according to claim 7, characterized in that: A stopper is movably disposed within the venting groove. Under normal temperature conditions, the stopper seals the venting groove under the action of elastic restoring force. When the gas pressure increases due to the thermal decomposition of the microencapsulated foaming agent in the third circumferential cavity, the stopper is pushed open by the gas pressure, thereby opening the venting groove.

9. A low-voltage fire-resistant insulated power cable according to claim 1, characterized in that: The annular connecting rib is provided with several limiting grooves. The limiting grooves cooperate with the plug to limit the displacement range of the plug in the unheated state and guide the plug to directionally detach from the vent groove under the action of gas pressure.

10. A low-voltage fire-resistant insulated power cable according to claim 1, characterized in that: When heated, the first circumferential cavity, the second circumferential cavity, and the third circumferential cavity sequentially trigger expansion, heat insulation, and gas generation reactions to form a tiered flame-retardant protection system.

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