A flame-retardant polyethylene sheathed cable

Abstract

The present invention relates to the field of cable technology, and discloses a flame-retardant polyethylene sheathed cable, comprising an outer cable sheath disposed on the outermost layer, an inner sheath disposed inside the outer cable sheath, a shielding layer disposed inside the inner sheath, and a conductor disposed inside the shielding layer; the outer cable sheath is provided with a flame-retardant component, the flame-retardant component comprising a hollow flame-retardant ring disposed on the outer wall of the outer cable sheath; one end of the flame-retardant ring is provided with a pre-triggering structure. The flame-retardant polyethylene sheathed cable, through the flame-retardant component and the pre-triggering structure, can achieve the early generation of a flame-retardant medium before the fire spreads to the flame-retardant component, and can block the fire when it spreads to the flame-retardant component. The cable is less affected by the temperature of the cable itself and the ambient temperature, and also solves the problem of traditional heat-expanding flame-retardant materials not responding in time, causing the fire to spread.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, 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 intumescent flame retardant systems (such as ammonium polyphosphate / pentaerythritol); the other is to design a heat-triggered structure, such as embedding intumescent 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 nearby 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, inability to block the initial fire, and difficulty in quickly forming 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 triggered by mistake 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 problems in the background art that the flame retardant of the prior art cable does not respond in time and is easily affected by the ambient temperature.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a flame-retardant polyethylene sheathed cable, comprising 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 provided on the outer cable sheath, and the flame-retardant component comprises a hollow flame-retardant ring arranged on the outer wall of the outer cable sheath, one end of the inner side of the flame-retardant ring is movably connected to an extrusion block, a liquid flame-retardant material is provided between one side of the extrusion 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 provided in the gap between the outer cable sheath and the inner sheath, and the solid flame-retardant material can react with the liquid flame-retardant material in contact to produce a flame-retardant medium, and the outer wall of the outer cable sheath is provided with a flame-retardant ring connected to the flame-retardant ring A through hole is provided on the inner side of the flame retardant ring, which is linked to the displacement of the extrusion block and is used to release the liquid flame retardant material into the inner part of the cable outer sheath through the through hole; one end of the flame retardant ring is provided with a pre-triggering structure, and the pre-triggering structure includes a pre-frame which is arranged on the outer wall of the cable outer sheath and close to one end of the extrusion block, and a push rod is movably provided on the pre-frame, and a connector which can be burned is provided at the end of the push rod away from the flame retardant ring, and the other end of the connector is fixedly connected to the cable outer sheath, and a protrusion is provided on the outer wall of the end of the push rod close to the connector, and an elastic part is provided between one end of the protrusion and the inner wall of the pre-frame. When the connector is in a connected state with the cable outer sheath, the elastic part is in a contracted state, and the end of the push rod away from the connector is used to push the extrusion block to move.

[0007] Preferably, the release structure includes a pressing groove arranged on the side wall of the extrusion block, and the inner side of the flame retardant ring is movably connected with a displacement piece corresponding to the pressing groove along the radial direction of the cable outer sheath, and a pointed cone corresponding to the through hole is provided on the side of the displacement piece facing the cable outer sheath, and a sealing piece is provided on the inside of the through hole. The inner wall of one end of the pressing groove is provided with a chamfer corresponding to the end of the displacement piece, so that when the extrusion block is displaced, the displacement piece can be pressed toward the direction of the cable outer sheath by the chamfer.

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

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

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

[0011] Preferably, separators are evenly arranged around the inner side of the flame retardant ring, and the liquid flame retardant material, the extrusion blocks and the through holes are all located in the cavity formed by adjacent separators.

[0012] Preferably, a sliding frame is movably provided at one end of the flame retardant ring, and a push rod extending to the inner side of the flame retardant ring and connected to the side wall of the extrusion block is provided on the side of the sliding frame close to the extrusion block, and the end of the push rod away from the connector is connected to the side wall of the sliding frame.

[0013] Preferably, annular sheets are evenly provided in the gap between the outer sheath and the inner sheath of the cable, and 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 an ammonium phosphate solution, and the liquid flame retardant material is disposed in a capsule made of polyurethane or gelatin;

[0015] The solid flame retardant material is sodium bicarbonate powder.

[0016] Preferably, reinforcing ribs are provided between the side walls of the front frame and the side walls of the flame retardant ring.

[0017] Compared with the prior art, the beneficial effects of the present invention include: 1. The flame-retardant polyethylene sheathed cable can realize the early generation of flame-retardant medium before the fire spreads to the flame-retardant component through the flame-retardant component provided and the pre-triggering structure, and can block the fire when it spreads to the flame-retardant component, and is less affected by the cable's own temperature and the ambient temperature. At the same time, it also solves the problem of fire spread caused by the traditional heat-expanding flame-retardant material not responding in time. 2. The flame-retardant polyethylene sheathed cable, the setting of the separator can separate the liquid flame-retardant material in the flame-retardant ring, and avoid the failure of the liquid flame-retardant material due to pressure damage on the outside of the flame-retardant ring, and can ensure the effectiveness of the liquid flame-retardant material in other parts when it is locally damaged. 3. The setting of the annular sheet of the flame-retardant polyethylene sheathed cable not only facilitates the storage of solid flame-retardant materials, but also divides the contact surface between the outer sheath of the cable and the inner sheath into multiple independent areas. When subjected to external force, the stress is dispersed and transmitted through the annular sheet to avoid local stress concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The disclosure of the present invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the accompanying 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 a structural diagram of the present invention from another perspective; Figure 3 Schematically shows a partial cross-sectional structural diagram of the present invention; Figure 4 The present invention is schematically shown Figure 3 Middle A enlarged view; Figure 5 The exploded structure diagram of the flame retardant ring and the front frame of the present invention is schematically shown; Figure 6 The present invention is schematically shown Figure 5 A structural diagram from another perspective based on the above; Figure 7 The schematic diagram shows the structure of the displacement plate, the pointed cone and the guide rod of the present invention in a disassembled state; Figure 8 The schematic structural diagram of the second embodiment of the release structure of the present invention is shown schematically.

[0019] Numbers in the figure: 1. Cable outer sheath; 2. Flame retardant ring; 3. Front frame; 4. Reinforcement rib; 5. Connector; 6. Push rod; 7. Ring piece; 8. Inner protective layer; 9. Shielding layer; 10. Filling layer; 11. Conductor; 12. Protrusion; 13. Elastic part; 14. Solid flame retardant material; 15. Through hole; 16. Sealing piece; 17. Sliding frame; 18. Push rod; 19. Extrusion block; 20. Liquid flame retardant material; 21. Cone; 22. Displacement piece; 23. Pressing groove; 24. Guide rod; 25. Separator; 26. Sealing ring; 27. Blocking piece; 28. Through groove. DETAILED DESCRIPTION

[0020] It is easy to understand that according to the technical solution of the present invention, without changing the essential spirit of the present invention, a person skilled in the art can propose a variety of interchangeable structural modes and implementation modes. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention and should not be regarded as the entire invention or as a limitation or restriction of the technical solution of the present invention.

[0021] According to the embodiment of the present invention, Figures 1-8 Shown.

[0022] First embodiment: Figure 1-Figure 7As shown, a flame retardant polyethylene sheathed cable comprises a cable outer sheath 1 arranged on the outermost layer, an inner sheath 8 is arranged on the inner side of the cable outer sheath 1, and a gap is arranged between the cable outer sheath 1 and the inner sheath 8, a shielding layer 9 is arranged inside the inner sheath 8, a conductor 11 is arranged on the inner side of the shielding layer 9, and a filling layer 10 is arranged in the gap between the conductors 11. The filling layer 10 is preferably ceramic silicone rubber, which is ceramicized at high temperature to form a hard insulation layer; different from the prior art, a flame retardant component is provided on the cable outer sheath 1, and the flame retardant component includes a hollow flame retardant ring 2 arranged on the outer wall of the cable outer sheath 1, and the flame retardant ring 2 is preferably A hard shell is selected, made of plastic or metal. One end of the inner side of the flame retardant ring 2 is movably connected to an extrusion block 19. A liquid flame retardant material 20 is provided between one side of the extrusion block 19 and one end of the inner side of the flame retardant ring 2. The liquid flame retardant material 20 is preferably an ammonium phosphate solution, and the liquid flame retardant material 20 is provided in a capsule of polyurethane or gelatin. The capsule of polyurethane or gelatin has water resistance, mechanical strength and thermal stability. The outer wall of the cable outer sheath 1 is provided with a through hole 15 that is connected to the flame retardant ring 2 and corresponds to the solid flame retardant material 14. A separator 25 is evenly arranged around the inner side of the flame retardant ring 2. The liquid flame retardant material 20, The extrusion block 19 and the through hole 15 are both located in the cavity formed by the adjacent separators 25. The setting of the separator 25 can separate the liquid flame retardant material 20 in the flame retardant ring 2 to avoid the external pressure damage of the flame retardant ring 2 causing the liquid flame retardant material 20 to fail. When local damage occurs, the effectiveness of the liquid flame retardant material 20 in other parts can be guaranteed. The gap between the cable outer sheath 1 and the inner sheath 8 is provided with a solid flame retardant material 14 corresponding to the flame retardant ring 2. 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. Ammonia itself is non-flammable and At a certain concentration, it can dilute the oxygen in the air, reduce the oxygen concentration around the combustibles, and inhibit combustion due to lack of oxygen. Carbon dioxide is a commonly used fire extinguishing agent. It does not burn or support combustion. Its density is greater than that of air. It can cover the surface of the combustibles, isolate the air, and thus prevent the continuation of combustion. Water absorbs a large amount of heat during the vaporization process, which can reduce the temperature of the combustibles to below the ignition point, playing a role in cooling and extinguishing the fire. Therefore, ammonium phosphate solution and sodium bicarbonate powder are preferred. Alternatively, other materials that are less affected by temperature and produce a flame retardant medium when the two come into contact can also replace ammonium phosphate solution and sodium bicarbonate powder.

[0023] Furthermore, annular sheets 7 are evenly arranged in the gap between the cable outer sheath 1 and the inner sheath 8, and the solid flame retardant material 14 is located between the two adjacent annular sheets 7 corresponding to the through hole 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 areas. When subjected to 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 in contact to produce a flame retardant medium. The 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 through the through hole 15 to the inside of the cable outer sheath 1. The release structure includes a pressing groove 23 arranged on the side wall of the extrusion block 19, and the inner side of the flame retardant ring 2 is connected with a displacement corresponding to the pressing groove 23 along the radial direction of the cable outer sheath 1. The sheet 22, specifically, a guide rod 24 corresponding to one end of the displacement sheet 22 is provided on the inner side of the flame retardant ring 2, and one end of the displacement sheet 22 is movably sleeved on the outside of the guide rod 24. In order to prevent the displacement sheet 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 the side of the displacement sheet 22 close to the cable outer sheath 1, so that the sealing ring 26 limits the displacement of the displacement sheet 22, and the friction between the sealing ring 26 and the guide rod 24 must be overcome before it can be displaced. The side of the displacement sheet 22 facing the cable outer sheath 1 is provided with a pointed cone 21 corresponding to the through hole 15, and a sealing sheet 16 is provided on the inside of the through hole 15. The pointed cone 21 is used to puncture the sealing sheet 16, and the inner wall of one end of the pressing groove 23 is provided with a chamfer corresponding to the end of the displacement sheet 22, so that when the extrusion block 19 is displaced, the displacement sheet 22 can be pressed toward the cable outer sheath 1 through the chamfer.

[0024] Furthermore, one end of the flame retardant ring 2 is provided with a front trigger structure, which includes a front frame 3 arranged on the 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 front frame 3. The push rod 6 is provided with a burnable connector 5 at one end away from the flame retardant ring 2. The connector 5 is preferably a thin rope or plastic filament, or other materials that can be burned can be replaced. The other end of the connector 5 is fixedly connected to the cable outer sheath 1. A protrusion 12 is provided on the outer wall of the end of the push rod 6 close to the connector 5. An elastic member 13 is provided between one end of the protrusion 12 and the inner wall of the front frame 3. The elastic member 13 is preferably a spring. And the spring sleeve is arranged on the outside of the push rod 6, which can increase the stability of the spring. When the connector 5 is connected to the cable outer sheath 1, the elastic part 13 is in a contracted state, and the end of the push rod 6 away from the connector 5 is used to push the extrusion block 19 to move. Specifically, a sliding frame 17 is movably provided at one end of the flame retardant ring 2, and a push rod 18 is provided on the side of the sliding frame 17 close to the extrusion block 19, which extends to the inner side of the flame retardant ring 2 and is connected to the side wall of the extrusion block 19. The end of the push rod 6 away from the connector 5 is connected to the side wall of the sliding frame 17, and in order to avoid bending at the push rod 6, a reinforcing rib 4 is provided between the side wall of the front frame 3 and the side wall of the flame retardant ring 2.

[0025] When the above scheme is used, the flame retardant rings 2 are arranged in pairs facing back to back, and the front frame 3 is located on the side 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 connector 5 will be burned 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 pressure groove 23 presses down the displacement piece 22, and one end of the displacement piece 22 enters the pressure groove 23. The displacement piece 22 drives the pointed cone 21 to pierce the sealing piece 16. At the same time, when one end of the displacement piece 22 enters the pressure groove 23, the pressure groove 23 can be blocked. As the extrusion block 19 moves, the liquid flame retardant material 20 is pressed into the gap between the adjacent annular pieces 7 through the through hole 15. The liquid flame retardant material 20 contacts and reacts with the solid flame retardant material 14 to produce a flame retardant medium. When the fire comes, the flame retardant medium leaks out to retard the burning area.

[0026] Second embodiment: Figure 8 As shown, unlike 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, and the end of the blocking piece 27 away from the extrusion block 19 is used to block the through hole 15, and the end of the blocking piece 27 close to the extrusion block 19 is provided with a through groove 28 corresponding to the through hole 15.

[0027] When the second embodiment is used, the flame retardant rings 2 are also arranged in pairs facing back to back, and the front frame 3 is located on the side 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 connector 5 will be burned 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 squeezes the liquid flame retardant material 20, and the liquid flame retardant material 20 is pressed into the gap between the adjacent annular pieces 7 through the through hole 15. The liquid flame retardant material 20 contacts the solid flame retardant material 14 and reacts to produce a flame retardant medium. When the fire comes, the flame retardant medium leaks out to retard the burning area.

[0028] The technical scope of the present invention is not limited to the contents of 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 by: The invention comprises 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 comprises a hollow flame retardant ring arranged on the outer wall of the outer cable sheath, one end of the inner side of the flame retardant ring is movably connected with an extrusion block, a liquid flame retardant material is arranged between one side of the extrusion 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 react with the liquid flame retardant material to produce a flame retardant medium, and the outer wall of the outer cable sheath is provided with a through hole connected to the flame retardant ring and corresponding to the solid flame retardant material, The inner side of the flame ring is provided with a release structure that is linked with the displacement of the extrusion block and is used to release the liquid flame retardant material into the inner part of the cable outer sheath through the through hole; one end of the flame retardant ring is provided with a pre-trigger structure, and the pre-trigger structure includes a pre-frame arranged on the outer wall of the cable outer sheath and close to one end of the extrusion block, and a push rod is movably provided on the pre-frame, and a connector that can be burned is provided at the end of the push rod away from the flame retardant ring, and the other end of the connector is fixedly connected to the cable outer sheath, and a protrusion is provided on the outer wall of the end of the push rod close to the connector, and an elastic part is provided between one end of the protrusion and the inner wall of the pre-frame. When the connector is in a connected state with the cable outer sheath, the elastic part is in a contracted state, and the end of the push rod away from the connector is used to push the extrusion block to move.

2. The flame-retardant polyethylene sheathed cable according to claim 1, characterized in that: The release structure includes a pressing groove arranged on the side wall of the extrusion block, and the inner side of the flame retardant ring is movably connected with a displacement piece corresponding to the pressing groove along the radial direction of the cable outer sheath. A pointed cone corresponding to the through hole is provided on the side of the displacement piece facing the cable outer sheath, and a sealing piece is provided on the inside of the through hole. The inner wall of one end of the pressing groove is provided with a chamfer corresponding to the end of the displacement piece, so that when the extrusion block is displaced, the displacement piece can be pressed toward the cable outer sheath by the chamfer.

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

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

5. The 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 extrusion block close to the liquid flame retardant material. The end of the blocking piece away from the extrusion block is used to block the through hole. The end of the blocking piece close to the extrusion block is provided with a through groove corresponding to the through hole.

6. The flame-retardant polyethylene sheathed cable according to claim 2 or 5, characterized in that: Separating sheets are evenly arranged around the inner side of the flame retardant ring, and the liquid flame retardant material, the extrusion block and the through hole are all located in the cavity formed by adjacent separating sheets.

7. The flame-retardant polyethylene sheathed cable according to claim 6, characterized in that: A sliding frame is movably provided at one end of the flame retardant ring, and a push rod extending to the inner side of the flame retardant ring and connected to the side wall of the extrusion block is provided on the side of the sliding frame close to the extrusion block, and the end of the push rod away from the connector is connected to the side wall of the sliding frame.

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

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

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