A self-extinguishing cable

Abstract

The present invention discloses a self-extinguishing cable in the field of wire and cable, which includes a conductor, an insulating layer is wrapped outside the conductor, a sheath is processed outside the insulating layer, the sheath includes a plurality of airbag strips evenly distributed in a ring shape, a first air cavity is arranged inside the airbag strip, and an inert gas is filled in the first air cavity. The present invention can effectively solve the problems that the fire prevention and flame retardancy of the existing technology still have defects, cannot effectively and reliably avoid the combustion of wire and cable, and cannot effectively avoid the spread of fire in time.

Description

Technical Field

[0001] The present invention relates to the field of cables, and particularly to a self-extinguishing cable. Background Art

[0002] As one of the important materials for modern social infrastructure construction, wire and cable are used to provide energy or transmit information for people's daily life, industrial production, information transmission, etc., and are an indispensable part of the infrastructure for modern social development. The main structure of the cable is a conductor wrapped with insulating material, and the outside of the insulating material is further wrapped with sheath material. The conductor is mainly a metal conductor. During the process of transmitting electric energy, certain heat will be generated due to the existence of resistance. Especially for some wires and cables with large transmission current and high voltage, a large amount of heat will be generated during use, and there is a phenomenon of spontaneous combustion caused by overheating during long-term use. In addition, there are also many cases of combustion of wire and cable caused by the influence of the external environment during use. Combustion will cause problems such as the failure of the insulating layer and the damage of the conductor of the wire and cable, and seriously cause fires endangering personal and property safety. Therefore, the fire prevention performance of wire and cable is particularly important. In the prior art, mainly by improving the insulating material and sheath material, researching and developing flame-retardant material components and adding them to the insulating layer or sheath layer, but usually for the multi-layer insulating structure of wire and cable, not every layer can add flame-retardant materials. In this way, the spontaneous combustion caused by the overheating of the cable itself can be avoided to a certain extent, but the spontaneous combustion cannot be completely avoided, and it is still possible to ignite some insulating materials and sheath materials due to overheating, and then ignite external objects to cause a fire. For external fire sources, only part of the insulating layer and sheath layer of the wire and cable can be prevented from being ignited. If there are sheath breaks or damages in the wire and cable, there is still a situation of being ignited. To sum up, the fire prevention and flame retardancy of existing wire and cable still have defects, and cannot effectively and reliably avoid the combustion of wire and cable, and cannot timely and effectively avoid the spread of fire. Summary of the Invention

[0003] The present invention aims to provide a self-extinguishing cable to solve the problems that the fire prevention and flame retardancy of the cable in the prior art still have defects, cannot effectively and reliably avoid the combustion of wire and cable, and cannot timely and effectively avoid the spread of fire.

[0004] To achieve the above object, the basic technical solution of the present invention is as follows: A self-extinguishing cable includes a conductor, an insulating layer is wrapped outside the conductor, a sheath layer is provided outside the insulating layer, and a plurality of airbag strips are evenly distributed in a ring on the outer wall of the sheath layer. A first air cavity is provided in the airbag strip, and an inert gas is filled in the first air cavity.

[0005] The principle and advantages of this solution are as follows: In practical applications, the conductor serves as the carrier for transmitting electrical energy, the insulating layer provides insulation protection for the conductor, the sheath layer provides outer structure protection for the cable, and multiple airbag strips wrap around the cable core on the outside. The first air chamber and the inert gas filled therein in the airbag strip rupture to release the inert gas when the cable encounters a fire, forming an inert gas layer near the surface of the cable to isolate the oxygen in the air, thereby extinguishing the flame on the surface of the cable and preventing the further spread of the fire. In addition, the airbag strips can also provide impact resistance and buffering for the cable when no fire occurs.

[0006] Furthermore, the cross-sectional profile of the airbag strip is semi-elliptical, and the first air chamber is concentrically arranged within the airbag strip, and the cross-sectional profile of the first air chamber is semi-circular. Preferably, in this way, the airbag strip forms an arched structure with a large edge thickness and a small middle thickness. The design of the wall thickness that gradually thins from both sides to the middle can concentrate the internal gas pressure at the thinnest point, that is, form a penetration point with the smallest wall thickness at the convex top of the airbag strip, which can rupture and release the inert gas first when encountering a fire. And due to the arched structure design of the airbag strip and the elastic material of the sheath layer, the airbag strip has the ability to maintain and recover a stable shape structure, so that the first air chamber will not open immediately after the penetration point ruptures, but slowly releases the inert gas, ensuring the coverage and coating of the inert gas on the surface of the cable, and ensuring the fire extinguishing and flame retardant effects of the inert gas on the cable.

[0007] Furthermore, adjacent airbag strips are in contact with each other. Preferably, in this way, the airbag strips are densely distributed on the surface of the sheath layer to completely cover the cable. Grooves are formed between adjacent airbag strips, and a continuous arc-shaped wave structure is formed on the surface of the entire cable. On the one hand, it has excellent impact resistance. On the other hand, after the penetration point of the airbag strip ruptures, the inert gas in the internal first air chamber can accumulate in the groove part, thereby effectively coating the surface of the cable and effectively isolating the oxygen in the air, ensuring the self-fire extinguishing and flame retardant effects of the cable.

[0008] Furthermore, a second air chamber surrounding the cable core is provided inside the sheath layer. The second air chamber divides the sheath layer into an inner sheath layer and an outer sheath layer, and the second air chamber is also filled with inert gas. Preferably, the second air chamber is located inside the sheath layer to form a second layer of fire protection structure through the inert gas. On the basis of the first air chamber in the airbag strip rupturing for fire extinguishing, the second air chamber can be used as a supplement. At this time, the groove concave points between adjacent airbag strips serve as the penetration points of the second air chamber, and then the inert gas in the second air chamber is also discharged to extinguish the flame on the surface of the cable and isolate the surface air, further improving the self-fire extinguishing and flame retardant performance of the cable and having better impact resistance.

[0009] Furthermore, the density of the inert gas in the first gas chamber is greater than that in the second gas chamber. Preferably, since the airbag strips are located on the outer side, the penetration points of the first gas chamber rupture prior to those of the second gas chamber between adjacent airbag strips. After the inert gas in the first gas chamber is released, the inert gas in the second gas chamber is then released. The denser inert gas in the first gas chamber can suppress the inert gas in the second gas chamber on the cable surface and prevent it from quickly dispersing. Thus, it ensures that the inert gas isolates the air on the cable surface, avoids the cable from being ignited, and further guarantees the self-extinguishing and flame-retardant effects of the cable.

[0010] Furthermore, at least three support strips connecting the inner sheath layer and the outer sheath layer are provided in the second gas chamber. Preferably, since the second gas chamber is annular, the inner sheath layer and the cable core are not supported. By providing the support strips, the inner sheath layer can be supported, and the inner sheath layer, the conductor, and the outer sheath layer can be concentrically arranged as much as possible, ensuring that the inner sheath layer can be effectively covered by the inert gas in the second gas chamber.

[0011] Furthermore, the support strips are located on the radial lines of the cross-sectional contour of the first gas chamber. Preferably, in this way, the support strips can stably support and separate the inner sheath layer and the outer sheath layer, and the support strips are located in the middle of the airbag strips. This can ensure that the penetration points of the second gas chamber between adjacent airbag strips are not occupied or blocked, guarantee that the second gas chamber can act timely and effectively, and avoid outward extrusion on the trough depressions between adjacent airbag strips, preventing unnecessary tearing at the trough parts.

[0012] Furthermore, the support strips are integrally formed on the surface of the inner sheath layer. Preferably, in this way, the processing and forming of the support strips can be synchronized with the processing of the inner sheath layer, making the processing more convenient and more conducive to covering the inner sheath layer with the second gas chamber at low cost, which is beneficial to cost reduction.

[0013] Furthermore, the parts of the first gas chamber and the second gas chamber at the cable end are heat-shrink sealed. Preferably, in this way, the cable end can conveniently and reliably seal the first gas chamber and the second gas chamber, effectively avoiding the leakage of inert gas and facilitating the use of cable joints.

[0014] Furthermore, a gas nozzle is hot-melt connected to the sheath layer or the airbag strip, and the gas nozzle penetrates into the first gas chamber or the second gas chamber. Preferably, by providing a gas nozzle on the sheath layer or the airbag strip, it is convenient to first form the first gas chamber and the second gas chamber and seal them, and then inject inert gas through the gas nozzle as needed. This can reduce the production and manufacturing costs and control the air pressure in the first gas chamber and the second gas chamber as needed, which is more conducive to ensuring the self-extinguishing performance of the cable.

[0015] Furthermore, the airbag strip is integrally formed with the outer sheath layer. As a preference, this is more conducive to reducing the processing costs of the outer sheath layer and the airbag strip, ensuring the structural integrity of the second air chamber penetration point, and effectively accommodating the inert gas in the second air chamber when not damaged by high temperature. Description of the Drawings

[0016] Figure 1 It is a schematic cross-sectional structure diagram of Embodiment 1 of the present invention. Specific Embodiments

[0017] The following is a further detailed description through specific embodiments:

[0018] The reference numerals in the accompanying drawings of the specification include: conductor 1, inner sheath layer 2, outer sheath layer 3, airbag strip 4, first air chamber 5, second air chamber 6, first air chamber penetration point 7, second air chamber penetration point 8, and support strip 9.

[0019] Embodiment 1 is basically as shown in the attached Figure 1 figure: A self-extinguishing cable includes a conductor 1, an insulating layer is wrapped outside the conductor 1, a sheath layer is coated outside the insulating layer, eight airbag strips 4 are evenly distributed in a ring on the outer wall of the sheath layer, the adjacent airbag strips 4 are in contact with each other, and the airbag strip 4 is integrally formed with the sheath layer. The cross-sectional profile of the airbag strip 4 is semi-elliptical, a first air chamber 5 is arranged inside the airbag strip 4, the cross-sectional profile of the first air chamber 5 is semi-circular, the first air chamber 5 is concentrically arranged inside the airbag strip 4, and an inert gas, preferably carbon dioxide, is filled in the first air chamber 5. A second air chamber 6 surrounding the conductor 1 is arranged inside the sheath layer, the second air chamber 6 divides the sheath layer into an inner sheath layer 2 and an outer sheath layer 3, an inert gas is also filled in the second air chamber 6, and the density of the inert gas in the second air chamber 6 is less than that of the inert gas in the first air chamber 5, preferably nitrogen.

[0020] Three support strips 9 distributed in a ring on the surface of the inner sheath layer 2 are arranged inside the second air chamber 6, the support strips 9 are integrally formed with the inner sheath layer 2, the support strips 9 are located on the radial line of the cross-sectional profile of the first air chamber 5, and the support strips 9 are in contact with the inner wall of the outer sheath layer 3. The parts of the first air chamber 5 and the second air chamber 6 at the end of the cable are heat-shrink sealed.

[0021] The specific implementation process is as follows: When the self-extinguishing cable is in use, the first air chamber 5 is filled with carbon dioxide gas, and the second air chamber 6 is filled with nitrogen. The first air chamber 5 and the second air chamber 6 are heat-shrink sealed at the end of the cable. The airbag strip 4 forms a continuous arched structure on the surface of the cable. The wall thickness of such an arched structure gradually thins from both sides to the middle, so that the gas pressure in the first air chamber 5 is concentrated at the thinnest part of the wall thickness, which is the penetration point 7 of the first air chamber. And at the lowest point of the trough between adjacent airbag strips 4, the thinnest part of the outer sheath material of the second air chamber 6 is formed, which is the penetration point 8 of the second air chamber. When a fire occurs during the use of the self-extinguishing cable, the temperature rises, and the air pressure in the first air chamber 5 and the second air chamber 6 increases. When the airbag strip 4 is damaged by the external flame burning or the overheated air pressure is too large, due to the arched design of the airbag strip 4, the penetration point 7 of the first air chamber is damaged before the penetration point 8 of the second air chamber. The carbon dioxide gas in the first air chamber 5 is released first, and the nitrogen in the second air chamber 6 is released later. And under the action of the arched design of the airbag strip 4, the carbon dioxide gas is released continuously and slowly. Based on the fact that the penetration point 7 of the first air chamber is farther from the conductor 1 than the penetration point 8 of the second air chamber, the carbon dioxide gas will suppress the nitrogen on the surface of the cable. The carbon dioxide gas and nitrogen isolate the air near the surface of the cable, so that the surface sheath of the burning cable loses the oxygen necessary for combustion and extinguishes. The surface layer of the unburned cable is effectively covered by the inert gas and isolated from oxygen to avoid ignition. In this way, during the use of the cable, when a fire occurs, the cable spontaneously completes the surface fire extinguishing and flame retardancy. Compared with the prior art that relies on the flame retardant components of the sheath material for flame retardancy, the present invention realizes fire extinguishing and flame retardancy by releasing the inert gas in the sheath layer to isolate the oxygen necessary for combustion. At the same time, the sheath layer can continue to be made of a sheath material with flame retardant components, further improving the fire extinguishing and flame retardancy effect on the basis of retaining the existing flame retardant performance, effectively and reliably avoiding the combustion of wires and cables, and being more conducive to timely and effective control of the fire, avoiding greater personal and property losses. And such a self-extinguishing cable has a double-layer air chamber structure formed in the sheath layer and a continuous arc-shaped contour on the surface, so that the self-extinguishing cable has better impact resistance and can be applied to more complex environments.

[0022] Embodiment 2. In this embodiment, two air nozzles are hot-melt connected to the sheath layer. One air nozzle penetrates into the first air chamber, and the other air nozzle penetrates into the second air chamber. In this embodiment, by setting air nozzles on the sheath layer, when the self-extinguishing cable has a stable structure after the sheath layer is produced and formed, the inert gas can be injected through the air nozzles, which is more convenient for controlling and maintaining the stable gas pressure in the first air chamber and the second air chamber. The operation of injecting the inert gas is more convenient, which is more conducive to reducing the production cost.

[0023] The above are only embodiments of the present invention, and common general knowledge of specific structures and / or characteristics in the solution is not described in detail herein. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several modifications and improvements can be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be subject to the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. A self-extinguishing cable, comprising a conductor, an insulating layer wrapped around the outside of the conductor, and a sheath layer provided on the outside of the insulating layer. It is characterized in that: A plurality of airbag strips are evenly distributed in a ring shape on the outer wall of the sheath layer. A first air cavity is provided in the airbag strip, and an inert gas is filled in the first air cavity; the cross-sectional profile of the airbag strip is semi-elliptical, the first air cavity is concentrically arranged in the airbag strip, and the cross-sectional profile of the first air cavity is semi-circular; a second air cavity surrounding the conductor is provided in the sheath layer, the second air cavity divides the sheath layer into an inner sheath layer and an outer sheath layer, and an inert gas is also filled in the second air cavity. A first penetration point is formed between the top of the first air cavity and the top of the airbag strip, and adjacent airbag strips are in contact with each other. A second penetration point is formed between the transition part between adjacent airbag strips and the second air cavity; the density of the inert gas in the first air cavity is greater than the density of the inert gas in the second air cavity.

2. A self-extinguishing cable according to claim 1, It is characterized in that: At least three support strips connecting the inner sheath layer and the outer sheath layer are provided in the second air cavity.

3. A self-extinguishing cable according to claim 2, It is characterized in that: The support strip is located on the radial line of the cross-sectional profile of the first air cavity.

4. A self-extinguishing cable according to claim 3, It is characterized in that: The support strip is integrally formed on the surface of the inner sheath layer.

5. A self-extinguishing cable according to claim 4, It is characterized in that: The parts of the first air cavity and the second air cavity at the end of the cable are heat-shrink sealed.

6. A self-extinguishing cable according to any one of claims 1-5, It is characterized in that: A nozzle is hot-melt connected to the insulating layer or the airbag strip.

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