Flame-retardant polyethylene sheath cable

Abstract

The invention relates to the technical field of cables, and discloses a flame-retardant polyethylene sheathed cable which comprises a cable outer sheath arranged on the outermost layer, an inner sheath arranged in the cable outer sheath, a shielding layer arranged in the inner sheath and a conductor arranged in the shielding layer. The cable outer sheath is provided with a flame-retardant component, and the flame-retardant component comprises a hollow flame-retardant ring which is arranged on the outer wall of the cable outer sheath. And a front trigger structure is arranged at one end of the flame-retardant ring. According to the flame-retardant polyethylene sheathed cable, the flame-retardant component is matched with the front trigger structure, so that a flame-retardant medium can be generated in advance before a fire spreads to the flame-retardant component, the fire can be blocked when the fire spreads to the flame-retardant component, and the influence of the temperature of the cable and the environment temperature is small; meanwhile, the problem of fire spreading caused by the fact that a traditional thermal expansion flame-retardant material does not respond in time is solved.

Description

Technical Field

[0001] The invention relates to the technical field of cables, and in particular to a flame-retardant polyethylene sheathed cable. Background Art

[0002] At present, flame-retardant polyethylene sheathed cables mainly improve their flame retardancy in two ways: one is to form a high-temperature resistant or carbonized barrier layer in the sheath or insulation layer by adding inorganic flame retardants (such as aluminum hydroxide, magnesium hydroxide) or expandable flame retardant systems (such as ammonium polyphosphate / pentaerythritol); the other is to design a heat-triggered structure, such as embedding expandable materials (such as expanded graphite) in the sheath, and triggering the material to expand or release flammable gas / liquid through high temperature to physically isolate the spread of flame. This type of technology relies on the flame retardant properties or thermal response mechanism of the material itself, which can delay the spread of fire to a certain extent.

[0003] However, in the existing scheme, the flame retardant whose flame retardant effect is triggered by heat needs to burn to the nearby area before it can gradually expand or release, and it takes a certain amount of time to be completely released or decomposed. Therefore, the decomposition rate of the flame retardant at high temperature sometimes does not match the flame spread speed, and the fire spread speed may far exceed the release / expansion time of the flame retardant, resulting in incomplete coverage of the flame retardant, unable to block the initial fire, and difficult to quickly form an effective protective layer. Moreover, the thermal expansion or flame retardant release structure is easily affected by the cable operation temperature rise or ambient temperature fluctuations, and may be mistakenly triggered or fail.

[0004] Therefore, it is necessary to propose a flame retardant polyethylene sheathed cable to solve the above problems. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art. The present invention proposes a flame-retardant polyethylene sheathed cable, which solves the problem that the flame retardant of the prior art cable in the background technology does not respond in time and is easily affected by the ambient temperature.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: A flame-retardant polyethylene sheathed cable includes an outer cable sheath provided on the outermost layer, an inner sheath provided inside the outer cable sheath, a shielding layer provided inside the inner sheath, and a conductor provided inside the shielding layer; a flame-retardant component is provided on the outer cable sheath, and the flame-retardant component includes a flame-retardant ring provided on the outer wall of the outer cable sheath and in a hollow shape. One end inside the flame-retardant ring is movably connected with a pressing block, and a liquid flame-retardant material is provided between one side of the pressing block and one end inside the flame-retardant ring. A solid flame-retardant material corresponding to the flame-retardant ring is provided in the gap between the outer cable sheath and the inner sheath, and the solid flame-retardant material can contact and react with the liquid flame-retardant material to generate a flame-retardant medium. Through holes corresponding to the flame-retardant ring and the solid flame-retardant material are provided on the outer wall of the outer cable sheath. Inside the flame-retardant ring, a release structure is provided which is linked to the displacement of the pressing block and is used to release the liquid flame-retardant material through the through holes into the inside of the outer cable sheath; one end of the flame-retardant ring is provided with a pre-trigger structure, and the pre-trigger structure includes a pre-frame provided on the outer wall of the outer cable sheath and close to one end of the pressing block. A push rod is movably provided on the pre-frame. One end of the push rod away from the flame-retardant ring is provided with a connective body that can be burned through, and the other end of the connective body is fixedly connected to the outer cable sheath. A protrusion is provided on the outer wall of the push rod close to the connective body, and an elastic member is provided between one end of the protrusion and the inner wall of the pre-frame. When the connective body is connected to the outer cable sheath, the elastic member is in a contracted state, and one end of the push rod away from the connective body is used to push the pressing block to displace.

[0007] Preferably, the release structure includes a pressing groove provided on the side wall of the pressing block. A displacement piece corresponding to the pressing groove is movably connected along the radial direction of the outer cable sheath inside the flame-retardant ring. A sharp cone corresponding to the through hole is provided on one side of the displacement piece facing the outer cable sheath. A sealing piece is provided inside the through hole, and a chamfer corresponding to the end of the displacement piece is provided on the inner wall of one end of the pressing groove, so that when the pressing block displaces, the displacement piece can be pressed to displace towards the outer cable sheath through the chamfer.

[0008] Preferably, a guide rod corresponding to one end of the displacement piece is provided inside the flame-retardant ring, and one end of the displacement piece is movably sleeved outside the guide rod.

[0009] Preferably, a sealing ring is sleeved on the guide rod, and the sealing ring is located on the side of the displacement piece close to the outer cable sheath.

[0010] Preferably, the release structure includes a blocking piece provided on the side of the pressing block close to the liquid flame-retardant material. One end of the blocking piece away from the pressing block is used to block the through hole, and a through groove corresponding to the through hole is provided on one end of the blocking piece close to the pressing block.

[0011] Preferably, partition pieces are evenly arranged in a circular manner inside the flame-retardant ring, and the liquid flame-retardant material, the pressing block, and the through holes are all located in the cavities formed by adjacent partition pieces.

[0012] Preferably, a sliding frame is movably arranged at one end of the flame retardant ring. A push rod extending to the inside of the flame retardant ring and connected to the side wall of the extrusion block is arranged on one side of the sliding frame close to the extrusion block. One end of the push rod away from the connecting body is connected to the side wall of the sliding frame.

[0013] Preferably, annular sheets are evenly arranged in the gap between the outer cable sheath and the inner sheath. The solid flame retardant material is located between two adjacent annular sheets corresponding to the through holes.

[0014] Preferably, the liquid flame retardant material is ammonium phosphate solution, and the liquid flame retardant material is arranged in a capsule made of polyurethane or gelatin; The solid flame retardant material is sodium bicarbonate powder.

[0015] Preferably, a reinforcing rib is arranged between the side wall of the front frame and the side wall of the flame retardant ring.

[0016] Compared with the prior art, the beneficial effects of the present invention include: 1. For this flame retardant polyethylene sheath cable, the flame retardant components and the front trigger structure can generate the flame retardant medium in advance before the fire spreads to the flame retardant components. When the fire spreads to the flame retardant components, the fire can be blocked. It is less affected by the temperature of the cable itself and the ambient temperature, and at the same time, it solves the problem that the traditional heat-expanded flame retardant material responds untimely and causes the spread of the fire. 2. For this flame retardant polyethylene sheath cable, the arrangement of the partition sheet can separate the liquid flame retardant material in the flame retardant ring, avoiding the failure of the liquid flame retardant material caused by the external pressure damage of the flame retardant ring. When a local part is damaged, the effectiveness of the liquid flame retardant material in other parts can be ensured. 3. For this flame retardant polyethylene sheath cable, the arrangement of the annular sheet not only facilitates the storage of the solid flame retardant material, but also can divide the contact surface between the outer cable sheath and the inner sheath into multiple independent regions. When subjected to external force, the stress is dispersed and transmitted through the annular sheet, avoiding local stress concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The disclosure of the present invention will be described with reference to the accompanying drawings. It should be understood that the drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the drawings, the same reference numerals are used to refer to the same components. Among them: Figure 1 Schematically shows the structural diagram of the present invention; Figure 2 Schematically shows the structural diagram of another perspective of the present invention; Figure 3 Schematically shows the partial sectional structural diagram of the present invention; Figure 4 Schematically shows the present invention Figure 3 The enlarged view of A in Figure 5 Schematically shows the exploded structural diagram of the flame retardant ring and the front frame of the present invention; Figure 6 Schematically shows the present invention Figure 5Schematic diagram of the structure from another perspective based on this; Figure 7 Schematically shows the structure diagram of the displacement sheet, the sharp cone, and the guide rod of the present invention in a disassembled state; Figure 8 Schematically shows the structure diagram of the second embodiment of the release structure of the present invention.

[0018] Reference numerals in the figure: 1. Outer cable sheath; 2. Flame-retardant ring; 3. Front bracket; 4. Reinforcing rib; 5. Connecting body; 6. Push rod; 7. Annular sheet; 8. Inner sheath; 9. Shielding layer; 10. Filling layer; 11. Conductor; 12. Protrusion; 13. Elastic member; 14. Solid flame-retardant material; 15. Through hole; 16. Sealing sheet; 17. Sliding bracket; 18. Push rod; 19. Extrusion block; 20. Liquid flame-retardant material; 21. Sharp cone; 22. Displacement sheet; 23. Groove; 24. Guide rod; 25. Partition sheet; 26. Sealing ring; 27. Plugging sheet; 28. Through groove. Specific embodiments

[0019] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, those of ordinary skill in the art can propose various interchangeable structural forms and implementation methods. Therefore, the following specific embodiments and the accompanying drawings are only illustrative descriptions of the technical solution of the present invention, and should not be regarded as the whole of the present invention or as a limitation or restriction on the technical solution of the present invention.

[0020] According to the embodiments of the present invention in combination with Figures 1-8 Shown as.

[0021] The first embodiment: As Figures 1-7As shown in the figure, a flame-retardant polyethylene sheathed cable includes a cable outer sheath 1 arranged on the outermost layer. An inner sheath 8 is arranged inside the cable outer sheath 1, and there is a gap between the cable outer sheath 1 and the inner sheath 8. A shielding layer 9 is arranged inside the inner sheath 8, and a conductor 11 is arranged inside the shielding layer 9. A filling layer 10 is arranged in the gap between the conductors 11. The filling layer 10 is preferably ceramicized silicone rubber, which forms a hard heat-insulating layer after being ceramicized at high temperature. Different from the prior art, a flame-retardant component is arranged on the cable outer sheath 1. The flame-retardant component includes a flame-retardant ring 2 arranged on the outer wall of the cable outer sheath 1 and in a hollow shape. The flame-retardant ring 2 is preferably made of a hard shell, plastic or metal material. One end inside the flame-retardant ring 2 is movably connected with an extrusion block 19. A liquid flame-retardant material 20 is arranged between one side of the extrusion block 19 and one end inside the flame-retardant ring 2. The liquid flame-retardant material 20 is preferably ammonium phosphate solution, and the liquid flame-retardant material 20 is arranged in a capsule made of polyurethane or gelatin. The capsule made of polyurethane or gelatin has water resistance, mechanical strength and thermal stability. A through hole 15 communicating with the flame-retardant ring 2 and corresponding to a solid flame-retardant material 14 is arranged on the outer wall of the cable outer sheath 1. Partition plates 25 are evenly arranged around the inside of the flame-retardant ring 2. The liquid flame-retardant material 20, the extrusion block 19 and the through hole 15 are all located in the cavity formed by adjacent partition plates 25. The arrangement of the partition plates 25 can separate the liquid flame-retardant material 20 in the flame-retardant ring 2, avoiding the failure of the liquid flame-retardant material 20 caused by the external pressure damage of the flame-retardant ring 2, and ensuring the effectiveness of the liquid flame-retardant material 20 in other parts in case of local damage. A solid flame-retardant material 14 corresponding to the flame-retardant ring 2 is arranged in the gap between the cable outer sheath 1 and the inner sheath 8. The solid flame-retardant material 14 is sodium bicarbonate powder. When the ammonium phosphate solution contacts the sodium bicarbonate powder, ammonia, carbon dioxide and water can be generated. Among them, ammonia itself is non-combustible, and at a certain concentration, it can dilute the oxygen in the air, reducing the oxygen concentration around the combustible material and inhibiting combustion due to lack of oxygen. Carbon dioxide is a commonly used fire extinguishing agent. It does not burn and does not support combustion, and has a density greater than that of air. It can cover the surface of the combustible material and isolate the air, thus preventing the continuation of combustion. Water will absorb a large amount of heat during the vaporization process, which can reduce the temperature of the combustible material to below the ignition point, playing a role in cooling and extinguishing the fire. Therefore, ammonium phosphate solution and sodium bicarbonate powder are preferably used, or other materials with little influence by temperature and generating a flame-retardant medium when the two contact can also replace ammonium phosphate solution and sodium bicarbonate powder.

[0022] Furthermore, annular sheets 7 are evenly arranged in the gap between the cable outer sheath 1 and the inner sheath 8. The solid flame retardant material 14 is located between two adjacent annular sheets 7 corresponding to the through holes 15. The arrangement of the annular sheets 7 not only facilitates the storage of the solid flame retardant material 14, but also divides the contact surface between the cable outer sheath 1 and the inner sheath 8 into multiple independent regions. When subjected to an external force, the stress is dispersed and transmitted through the annular sheets 7 to avoid local stress concentration. The solid flame retardant material 14 can react with the liquid flame retardant material 20 to generate a flame retardant medium. An inner side of the flame retardant ring 2 is provided with a release structure that is linked to the displacement of the extrusion block 19 and is used to release the liquid flame retardant material 20 into the interior of the cable outer sheath 1 through the through holes 15. The release structure includes a pressure groove 23 provided on a side wall of the extrusion block 19. An inner side of the flame retardant ring 2 is movably connected along the radial direction of the cable outer sheath 1 with a displacement piece 22 corresponding to the pressure groove 23. Specifically, a guide rod 24 corresponding to one end of the displacement piece 22 is provided on the inner side of the flame retardant ring 2. One end of the displacement piece 22 is movably sleeved outside the guide rod 24. In order to prevent the displacement piece 22 from easily moving with the guide rod 24, a sealing ring 26 is sleeved on the guide rod 24, and the sealing ring 26 is located on a side of the displacement piece 22 close to the cable outer sheath 1. Thus, the sealing ring 26 restricts the displacement of the displacement piece 22, and it is necessary to overcome the frictional force between the sealing ring 26 and the guide rod 24 to displace. A sharp cone 21 corresponding to the through hole 15 is provided on a side of the displacement piece 22 facing the cable outer sheath 1. A sealing piece 16 is provided inside the through hole 15. The sharp cone 21 is used to pierce the sealing piece 16. A chamfer corresponding to an end of the displacement piece 22 is provided on an inner wall of one end of the pressure groove 23. Thus, when the extrusion block 19 displaces, the displacement piece 22 can be pressed to displace towards the cable outer sheath 1 through the chamfer.

[0023] Furthermore, a pre-trigger structure is provided at one end of the flame retardant ring 2. The pre-trigger structure includes a pre-frame 3 provided on an outer wall of the cable outer sheath 1 and close to one end of the extrusion block 19. A push rod 6 is movably provided on the pre-frame 3. A breakable connecting body 5 is provided at an end of the push rod 6 far from the flame retardant ring 2. The connecting body 5 is preferably a thin string or a plastic filament, or other burnable materials can be substituted. The other end of the connecting body 5 is fixedly connected to the cable outer sheath 1. A protrusion 12 is provided on an outer wall of the push rod 6 close to the connecting body 5. An elastic member 13 is provided between one end of the protrusion 12 and an inner wall of the pre-frame 3. The elastic member 13 is preferably a spring, and the spring is sleeved outside the push rod 6 to increase the stability of the spring. When the connecting body 5 is in a connected state with the cable outer sheath 1, the elastic member 13 is in a contracted state. The end of the push rod 6 far from the connecting body 5 is used to push the extrusion block 19 to displace. Specifically, a sliding frame 17 is movably provided at one end of the flame retardant ring 2. A push rod 18 extending to the inner side of the flame retardant ring 2 and connected to a side wall of the extrusion block 19 is provided on a side of the sliding frame 17 close to the extrusion block 19. The end of the push rod 6 far from the connecting body 5 is connected to a side wall of the sliding frame 17. And in order to prevent the push rod 6 from being bent, a reinforcing rib 4 is provided between a side wall of the pre-frame 3 and a side wall of the flame retardant ring 2.

[0024] When the above solution is used, the flame retardant rings 2 are arranged in pairs and back to back, and the front frame 3 is located on the side far away from the two flame retardant rings 2, so that the fire in two directions can be blocked. Specifically, when the fire spreads at one end, the connecting body 5 will be burned off first, and then the elastic member 13 drives the push rod 6, the sliding frame 17, the push rod 18, and the extrusion block 19 to move as a whole through the protrusion 12. The chamfer in the pressing groove 23 presses down the displacement piece 22, one end of the displacement piece 22 enters the pressing groove 23, the displacement piece 22 drives the sharp cone 21 to pierce the sealing piece 16, and at the same time, when one end of the displacement piece 22 enters the pressing groove 23, it can block the pressing groove 23. As the extrusion block 19 moves, the liquid flame retardant material 20 is pressed into the gap between adjacent annular pieces 7 through the through hole 15. The liquid flame retardant material 20 reacts with the solid flame retardant material 14 to generate a flame retardant medium. When the fire comes, the flame retardant medium leaks out to retard the combustion area.

[0025] Second Embodiment: As Figure 8 shown, different from the first embodiment, the release structure includes a blocking piece 27 arranged on the side of the extrusion block 19 close to the liquid flame retardant material 20. One end of the blocking piece 27 away from the extrusion block 19 is used to block the through hole 15, and a through groove 28 corresponding to the through hole 15 is arranged at one end of the blocking piece 27 close to the extrusion block 19.

[0026] When the second embodiment is used, the flame retardant rings 2 are also arranged in pairs and back to back, and the front frame 3 is located on the side far away from the two flame retardant rings 2, so that the fire in two directions can be blocked. Specifically, when the fire spreads at one end, the connecting body 5 will be burned off first, and then the elastic member 13 drives the push rod 6, the sliding frame 17, the push rod 18, the extrusion block 19, and the blocking piece 27 to move as a whole through the protrusion 12. As the extrusion block 19 moves, one end of the blocking piece 27 moves away from the through hole 15, and then the through groove 28 corresponds to the through hole 15. The extrusion block 19 extrudes the liquid flame retardant material 20, and the liquid flame retardant material 20 is pressed into the gap between adjacent annular pieces 7 through the through hole 15. The liquid flame retardant material 20 reacts with the solid flame retardant material 14 to generate a flame retardant medium. When the fire comes, the flame retardant medium leaks out to retard the combustion area.

[0027] The technical scope of the present invention is not limited to the content in the above description. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of the present invention, and these deformations and modifications should all fall within the protection scope of the present invention.

Claims

1. A flame-retardant polyethylene sheathed cable, characterized in that: It includes an outer cable sheath arranged on the outermost layer, an inner sheath arranged inside the outer cable sheath, a shielding layer arranged inside the inner sheath, and a conductor arranged inside the shielding layer; a flame-retardant component is arranged on the outer cable sheath, and the flame-retardant component includes a flame-retardant ring arranged on the outer wall of the outer cable sheath and in a hollow shape. One end of the inner side of the flame-retardant ring is movably connected with a pressing block, and a liquid flame-retardant material is arranged between one side of the pressing block and one end of the inner side of the flame-retardant ring. A solid flame-retardant material corresponding to the flame-retardant ring is arranged in the gap between the outer cable sheath and the inner sheath, and the solid flame-retardant material can contact and react with the liquid flame-retardant material to generate a flame-retardant medium. A through hole corresponding to the flame-retardant ring and the solid flame-retardant material is arranged on the outer wall of the outer cable sheath. A release structure is arranged on the inner side of the flame-retardant ring and is linked with the displacement of the pressing block and is used to release the liquid flame-retardant material into the inner part of the outer cable sheath through the through hole; a pre-trigger structure is arranged at one end of the flame-retardant ring. The pre-trigger structure includes a pre-frame arranged on the outer wall of the outer cable sheath and close to one end of the pressing block. A push rod is movably arranged on the pre-frame. A connective body that can be burned off is arranged at the end of the push rod far from the flame-retardant ring. The other end of the connective body is fixedly connected with the outer cable sheath. A protrusion is arranged on the outer wall of the push rod close to the connective body. An elastic member is arranged between one end of the protrusion and the inner wall of the pre-frame. When the connective body is connected with the outer cable sheath, the elastic member is in a contracted state. The end of the push rod far from the connective body is used to push the pressing block to displace.

2. A flame-retardant polyethylene sheathed cable according to claim 1, wherein: The release structure includes a pressure groove arranged on the side wall of the pressing block. A displacement piece corresponding to the pressure groove is movably connected along the radial direction of the outer cable sheath on the inner side of the flame-retardant ring. A sharp cone corresponding to the through hole is arranged on the side of the displacement piece facing the outer cable sheath. A sealing piece is arranged inside the through hole. A chamfer corresponding to the end part of the displacement piece is arranged on the inner wall of one end of the pressure groove, so that when the pressing block displaces, the displacement piece can be pressed to displace towards the outer cable sheath through the chamfer.

3. A flame-retardant polyethylene sheathed cable according to claim 2, characterized in that: A guide rod corresponding to one end of the displacement piece is arranged on the inner side of the flame-retardant ring, and one end of the displacement piece is movably sleeved outside the guide rod.

4. A flame-retardant polyethylene sheathed cable according to claim 3, wherein: A sealing ring is sleeved on the guide rod, and the sealing ring is located on the side of the displacement piece close to the outer cable sheath.

5. A flame-retardant polyethylene sheathed cable according to claim 1, characterized in that: The release structure includes a blocking piece arranged on the side of the pressing block close to the liquid flame-retardant material. The end of the blocking piece far from the pressing block is used to block the through hole. A through groove corresponding to the through hole is arranged on the end of the blocking piece close to the pressing block.

6. A flame-retardant polyethylene sheathed cable according to claim 2 or 5, characterized in that: Partition pieces are evenly arranged in a surrounding manner on the inner side of the flame-retardant ring. The liquid flame-retardant material, the pressing block, and the through hole are all located in the cavity formed by adjacent partition pieces.

7. A flame-retardant polyethylene sheathed cable according to claim 6, characterized in that: A sliding frame is movably arranged at one end of the flame-retardant ring. A push rod extending to the inner side of the flame-retardant ring and connected with the side wall of the pressing block is arranged on the side of the sliding frame close to the pressing block. The end of the push rod far from the connective body is connected with the side wall of the sliding frame.

8. A flame-retardant polyethylene sheathed cable according to claim 6, characterized in that: Annular pieces are evenly arranged in the gap between the outer cable sheath and the inner sheath, and the solid flame-retardant material is located between two adjacent annular pieces corresponding to the through hole.

9. A flame-retardant polyethylene sheathed cable according to claim 8, characterized in that: The liquid flame-retardant material is ammonium phosphate solution, and the liquid flame-retardant material is arranged in a capsule made of polyurethane or gelatin; the solid flame-retardant material is sodium bicarbonate powder.

10. A flame-retardant polyethylene sheathed cable according to claim 2 or 5, characterized in that: Reinforcing ribs are provided between the side wall of the front frame and the side wall of the flame retardant ring.

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