Flame-retardant fireproof cable for rail transit

Abstract

The utility model relates to the technical field of cables, in particular to a flame-retardant fireproof cable for rail transit, which comprises a cable core, a shielding layer, a composite flame-retardant layer and an outer sheath, a pinning layer capable of increasing the tensile strength of the composite flame-retardant layer is arranged between every two adjacent outer flame-retardant layers, and each pinning layer is formed by weaving a plurality of tensile fiber ropes in a staggered mode, so that weaving gaps capable of increasing the adhesive force between the outer flame-retardant layers and the pinning layers are formed in the pinning layers; the composite flame-retardant layer composed of the outer flame-retardant layer and the containing layer is arranged, the weaving gap formed by the containing layer is utilized, the adhesive force between the outer flame-retardant layer and the containing layer is increased, when the cable is bent, twisted and deformed, the fluidity of the outer flame-retardant layer when the outer flame-retardant layer is extruded is reduced, and the thickness consistency of the outer flame-retardant layer is maintained; and local thinning of the outer flame-retardant layer caused by bending, deformation and extrusion of the cable is avoided.

Description

Technical Field

[0001] This utility model relates to the field of cable technology, and more specifically to a flame-retardant and fireproof cable for rail transit. Background Technology

[0002] In rail transit systems, cables are widely used in key components such as train running lines, station power supply systems, signaling systems, communication systems, and train traction systems. Because rail transit lines are mostly located in underground tunnels, the environment is relatively enclosed with poor ventilation and heat dissipation, making it easier for flames and smoke to accumulate in the event of a fire. Therefore, strict requirements are placed on the fire-resistant and flame-retardant properties of cables.

[0003] To meet the fire-retardant performance requirements of rail transit cables, current designs typically use fire-retardant materials for the outer sheath of the cable. Further fire-retardant fillers, such as magnesium hydroxide, expanded graphite, and fire-retardant mortar, can be used inside the cable for additional fire protection. However, the behavior of these fillers inside the cable has certain limitations. Especially when the cable is bent, twisted, or subjected to external pressure during practical applications, the filler will diffuse outwards along the direction of force. Furthermore, the different properties of the materials between the cable's structural layers lead to variations in their coefficients of thermal expansion and mechanical strength under stress or high temperatures, further exacerbating the filler flow problem. This results in reduced filler density and thickness in some areas, directly affecting the fire-retardant effect in those areas and ultimately weakening the overall fire safety and reliability of the cable. Utility Model Content

[0004] To address the technical problems existing in the current flame-retardant and fire-resistant cables for rail transit, the first aspect of this utility model proposes a flame-retardant and fire-resistant cable for rail transit, comprising:

[0005] Cable core;

[0006] The shielding layer is wrapped around the outside of the cable core;

[0007] A composite flame-retardant layer is wrapped around the outside of the shielding layer;

[0008] The outer sheath is extruded onto the outside of the composite flame-retardant layer;

[0009] The composite flame retardant layer includes multiple layers of outer flame retardant layers arranged sequentially from the inside to the outside, and a restraining layer that can increase the tensile strength of the composite flame retardant layer is arranged between adjacent outer flame retardant layers.

[0010] The restraining layer is configured to be composed of multiple tensile fiber ropes interwoven together, so that the restraining layer forms a weaving gap that can increase the adhesion between the outer flame retardant layer and the restraining layer.

[0011] A buffer layer is provided between the shielding layer and the composite flame-retardant layer, so that an elastic gap that can be compressed is formed between the shielding layer and the composite flame-retardant layer.

[0012] Preferably, an inner flame-retardant layer is provided between the shielding layer and the buffer layer.

[0013] Preferably, the tensile fiber rope is made of multiple strands of aramid filament twisted together, and the diameter of the tensile fiber rope is 0.5-0.8 mm.

[0014] Preferably, the shielding layer is made by wrapping aluminum foil around the outside of the cable core, and the number of wrapping layers is 1, with a wrapping overlap rate of 25%.

[0015] Preferably, the buffer layer comprises flame-retardant conductive foam, and the thickness of the buffer layer is 0.8-1.5cm.

[0016] Preferably, the cable core includes multiple tangent cores and a wrapping layer, wherein the multiple cores are wrapped together by the wrapping layer to form a shape.

[0017] Preferably, the slits between the multiple cores are filled with a water-blocking layer.

[0018] Preferably, the wire core includes a conductor and a protective layer, the protective layer being extruded over the outside of the conductor.

[0019] Preferably, the conductor is made of several strands of annealed copper wire twisted together in a 1+6+12 structure, with the inner and outer layers twisted in opposite directions, the inner layer twist pitch ratio being 10 times, and the outer layer twist pitch ratio being 8 times.

[0020] Preferably, the protective layer is configured as a three-layer co-extruded layer comprising a conductor shielding layer, an insulating layer, and an insulating shielding layer, formed by a co-extrusion process.

[0021] Compared with existing technologies, the significant advantages of this utility model of flame-retardant and fire-resistant cable for rail transit are:

[0022] 1. By setting up a composite flame-retardant layer consisting of an outer flame-retardant layer and a restraining layer, the adhesion between the outer flame-retardant layer and the restraining layer is increased by utilizing the braided gaps formed by the restraining layer. When the cable is bent and twisted, the flow resistance of the outer flame-retardant layer increases, reducing the fluidity of the outer flame-retardant layer when it is squeezed, maintaining the consistency of the thickness of the outer flame-retardant layer, and avoiding the reduction of flame-retardant performance caused by the local thinning of the outer flame-retardant layer due to the bending and deformation of the cable.

[0023] 2. By setting a buffer layer between the shielding layer and the composite flame retardant layer, a compressible elastic gap is formed between the shielding layer and the composite flame retardant layer. When the cable is bent or twisted and deformed, the buffer layer is compressed, thereby reducing the degree of deformation of the composite flame retardant layer and further reducing the local thinning of the outer flame retardant layer due to compression, thus maintaining the consistency of the thickness of the outer flame retardant layer.

[0024] 3. Because the composite flame-retardant layer has a restraining layer made of aramid fiber inside, the overall tensile strength of the composite flame-retardant layer is high. The composite flame-retardant layer binds the inner flame-retardant layer and the buffer layer, and the buffer layer has good elasticity. Therefore, when a deflagration occurs inside the cable, the increased pressure due to the deflagration is absorbed to the maximum extent by the deformation of the buffer layer. At the same time, under the restraining effect of the composite flame-retardant layer, the high-temperature metal particles generated by the deflagration are bound inside the cable, preventing the high-temperature metal particles generated by the deflagration inside the cable from igniting external combustibles, thus improving the flame-retardant performance. Attached Figure Description

[0025] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in the various figures may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings.

[0026] Figure 1 This is a structural schematic diagram of the flame-retardant and fireproof cable for rail transit shown in this utility model.

[0027] Figure 2 This is a schematic diagram of the radial cross-section of the flame-retardant and fireproof cable for rail transit shown in this utility model.

[0028] Figure 3 This is a schematic diagram of the axial cross-section of the composite flame-retardant layer in the flame-retardant and fire-resistant cable for rail transit shown in this utility model.

[0029] Figure 4 This is a schematic diagram of the structure of the restraining layer in the flame-retardant and fireproof cable for rail transit shown in this utility model.

[0030] The definitions of the various reference numerals in the figure are as follows:

[0031] 1. Conductor; 11. Protective layer; 2. Filler layer; 3. Wrapping layer; 4. Shielding layer; 5. Inner flame retardant layer; 6. Buffer layer; 7. Composite flame retardant layer; 71. Outer flame retardant layer; 72. Restraining layer; 721. Braided gap; 8. Outer sheath. Detailed Implementation

[0032] To better understand the technical content of this utility model, specific embodiments are provided below in conjunction with the accompanying drawings.

[0033] Combined with this utility model Figures 1-4 The fire-retardant cable for rail transit shown in the embodiment includes a cable core, a shielding layer 4, a composite fire-retardant layer 7, and an outer sheath 8.

[0034] The cable core comprises multiple tangentially connected cores and a wrapping layer 3. The slits between the cores are filled with a water-blocking layer 2. The cores and the filling layer 2 are then wrapped together by the wrapping layer 3 to form a circular cross-section. In the illustrated example, three cores are used to illustrate how the filling and wrapping process creates a circular cross-section.

[0035] In an optional embodiment, the filling layer 2 is filled with water-resistant yarn, which can play a good water-resistant role.

[0036] In a specific embodiment, the wrapping layer 3 includes a polyester tape, which is used to wrap and solidify the wire core and the filling layer 2 together in a spiral wrapping manner, and wraps it into a cable core with a circular radial cross section.

[0037] Furthermore, the wire core includes conductor 1 and protective layer 11. The protective layer 11 is extruded on the outside of conductor 1. Conductor 1 is made of several strands of annealed copper wire twisted together in a 1+6+12 structure. The inner and outer layers are twisted in opposite directions. The inner layer twist pitch ratio is 10 times, and the outer layer twist pitch ratio is 8 times. The smaller twist pitch makes conductor 1 more flexible, with good bending characteristics, thus improving the flexibility of the cable.

[0038] In a specific embodiment, the protective layer 11 is configured as a three-layer co-extruded layer including a conductor shielding layer, an insulation layer, and an insulation shielding layer, with the insulation made of cross-linked polyethylene and both the conductor shielding and the insulation shielding made of semi-conductive polyolefin.

[0039] Furthermore, the shielding layer 4 is made by wrapping aluminum foil around the outside of the wrapping layer 3, and the number of wrapping layers is 1, with a wrapping overlap rate of 25%, which can play an electromagnetic shielding role, improve the electromagnetic shielding effect of the cable, and prevent the electrical signals transmitted by the cable from being interfered with.

[0040] Combination Figure 2 , Figure 3 and Figure 4 As shown, the composite flame retardant layer 7 covers the outside of the shielding layer 4. The composite flame retardant layer 7 includes multiple layers of outer flame retardant layers 71 arranged sequentially from the inside to the outside, and a restraining layer 72 is arranged between adjacent outer flame retardant layers 71. The restraining layer 72 is configured to be composed of multiple tensile fiber ropes interwoven, so that a braided gap 721 is formed on the restraining layer 72, which can increase the adhesion between the outer flame retardant layer 71 and the restraining layer 72. When the cable is bent and twisted, the flow resistance of the outer flame retardant layer 71 increases, reducing the fluidity of the outer flame retardant layer 71 when squeezed, and maintaining the consistency of the thickness of the outer flame retardant layer 71.

[0041] In an optional embodiment, the outer flame-retardant layer 71 is made of fire-retardant putty, which has good fire-retardant properties, and is soft and malleable, which enables the cable to have good flexibility. At the same time, under the restraint of the restraining layer 72, it can reduce its fluidity when squeezed, maintain the consistency of the thickness of the outer flame-retardant layer 71, and avoid the local thinning of the outer flame-retardant layer 71 due to the bending deformation and squeezing of the cable, which would lead to a reduction in flame-retardant performance.

[0042] Furthermore, a buffer layer 6 is provided between the shielding layer 4 and the composite flame-retardant layer 7, so that an elastic gap that can be compressed is formed between the shielding layer 4 and the composite flame-retardant layer 7. When the cable is bent or twisted and deformed, the buffer layer 6 is compressed, thereby reducing the degree of deformation of the composite flame-retardant layer 7, further reducing the local thinning of the outer flame-retardant layer 71 due to compression, and maintaining the consistency of the thickness of the outer flame-retardant layer 71.

[0043] In a specific embodiment, the tensile fiber rope is made of multiple strands of aramid filament twisted together, and the diameter of the tensile fiber rope is 0.5-0.8mm, preferably 0.8mm, so that the restraining layer 72 composed of the interlaced tensile fiber rope has high tensile strength, thereby improving the overall tensile performance of the cable.

[0044] In an optional embodiment, the buffer layer 6 includes flame-retardant conductive foam, and the thickness of the buffer layer 6 is 0.8-1.5cm, preferably 1.5cm, which can provide a larger buffer space. The flame-retardant conductive foam has a good electromagnetic shielding effect, which improves the electromagnetic shielding effect of the cable and prevents the electrical signals transmitted by the cable from being interfered with.

[0045] Combination Figure 3 As shown, an inner flame-retardant layer 5 is provided between the shielding layer 4 and the buffer layer 6, so that both the outer and inner sides of the buffer layer 6 are covered with flame-retardant material. The outer flame-retardant material is used to isolate external fire sources, and the inner flame-retardant material is used to isolate high-temperature metal particles generated when insulation breakdown occurs inside the cable, so as to prevent high-temperature metal particles generated inside the cable due to insulation breakdown from igniting external combustibles and improve flame-retardant performance.

[0046] Furthermore, because the composite flame-retardant layer 7 has a restraining layer 72 made of aramid fiber inside, the overall tensile strength of the composite flame-retardant layer 7 is high. The composite flame-retardant layer 7 binds the inner flame-retardant layer 5 and the buffer layer 6, and the buffer layer 6 has good elasticity. Therefore, when a deflagration occurs inside the cable, the increased pressure due to the deflagration is absorbed by the deformation of the buffer layer 6 to the maximum extent. At the same time, under the restraining effect of the composite flame-retardant layer 7, the high-temperature metal particles generated by the deflagration are bound inside the cable, preventing the high-temperature metal particles generated by the deflagration inside the cable from igniting external combustibles, thus improving the flame-retardant performance.

[0047] In a preferred embodiment, the inner flame-retardant layer 5 is made of fireproof putty, which has good fire-retardant properties and is soft and malleable, enabling the cable to have good flexibility.

[0048] Combination Figure 1 As shown, the outer sheath 8 is extruded on the outside of the composite flame retardant layer 7. The outer sheath 8 is made of low-smoke halogen-free flame retardant polyolefin material, which has good flame retardant properties and low smoke emission and is non-toxic when burning.

[0049] In conjunction with the above embodiments, by setting a composite flame-retardant layer 7 composed of an outer flame-retardant layer 71 and a restraining layer 72, the adhesion between the outer flame-retardant layer 71 and the restraining layer 72 is increased by utilizing the braided gap 721 formed by the restraining layer 72. When the cable undergoes bending and torsional deformation, the flow resistance of the outer flame-retardant layer 71 increases, reducing the fluidity of the outer flame-retardant layer 71 under compression, maintaining the consistency of the thickness of the outer flame-retardant layer 71, and avoiding the reduction of flame-retardant performance caused by the local thinning of the outer flame-retardant layer 71 due to the bending deformation and compression of the cable.

[0050] By setting a buffer layer 6 between the shielding layer 4 and the composite flame retardant layer 7, a compressible elastic gap is formed between the shielding layer 4 and the composite flame retardant layer 7. When the cable is bent or twisted and deformed, the buffer layer 6 is compressed, thereby reducing the degree of deformation of the composite flame retardant layer 7 and further reducing the local thinning of the outer flame retardant layer 71 due to compression, thus maintaining the consistency of the thickness of the outer flame retardant layer 71.

[0051] Because the composite flame retardant layer 7 has a restraining layer 72 made of aramid fiber inside, the overall tensile strength of the composite flame retardant layer 7 is high. The composite flame retardant layer 7 binds the inner flame retardant layer 5 and the buffer layer 6. The buffer layer 6 has good elasticity. Therefore, when a deflagration occurs inside the cable, the increased pressure due to the deflagration is absorbed by the deformation of the buffer layer 6 to the maximum extent. At the same time, under the restraining effect of the composite flame retardant layer 7, the high-temperature metal particles generated by the deflagration are bound inside the cable, preventing the high-temperature metal particles generated by the deflagration inside the cable from igniting external combustibles, thus improving the flame retardant performance.

[0052] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Those skilled in the art to which this invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of this invention shall be determined by the claims.

Claims

1. A flame-retardant and fire-resistant cable for rail transit, characterized in that, include: Cable core; The shielding layer (4) is wrapped around the outside of the cable core; A composite flame-retardant layer (7) is wrapped around the outside of the shielding layer (4); The outer sheath (8) is extruded onto the outside of the composite flame-retardant layer (7); The composite flame retardant layer (7) includes multiple layers of outer flame retardant layers (71) arranged sequentially from the inside to the outside, and a restraining layer (72) that can increase the tensile strength of the composite flame retardant layer (7) is arranged between adjacent outer flame retardant layers (71). The restraining layer (72) is configured to be composed of multiple tensile fiber ropes interwoven, so that the restraining layer (72) forms a weaving gap (721) that can increase the adhesion between the outer flame retardant layer (71) and the restraining layer (72); Furthermore, a buffer layer (6) is arranged between the shielding layer (4) and the composite flame-retardant layer (7), so that a compressible elastic gap is formed between the shielding layer (4) and the composite flame-retardant layer (7).

2. The flame-retardant and fire-resistant cable for rail transit according to claim 1, characterized in that, An inner flame-retardant layer (5) is provided between the shielding layer (4) and the buffer layer (6).

3. The flame-retardant and fire-resistant cable for rail transit according to claim 1, characterized in that, The tensile fiber rope is made of multiple strands of aramid filament twisted together, and the diameter of the tensile fiber rope is 0.5-0.8 mm.

4. The flame-retardant and fire-resistant cable for rail transit according to claim 1, characterized in that, The shielding layer (4) is made by wrapping aluminum foil around the outside of the cable core, and the number of wrapping layers is 1, with a wrapping overlap rate of 25%.

5. The flame-retardant and fire-resistant cable for rail transit according to claim 1, characterized in that, The buffer layer (6) includes flame-retardant conductive foam, and the thickness of the buffer layer (6) is 0.8-1.5cm.

6. The flame-retardant and fire-resistant cable for rail transit according to claim 1, characterized in that, The cable core includes multiple tangent cores and a wrapping layer (3), and the multiple cores are wrapped and fixed together by the wrapping layer (3).

7. The flame-retardant and fire-resistant cable for rail transit according to claim 1, characterized in that, The slits between the multiple cores are filled with a water-blocking filler layer (2).

8. The flame-retardant and fire-resistant cable for rail transit according to claim 1, characterized in that, The core includes a conductor (1) and a protective layer (11), the protective layer (11) being extruded over the outside of the conductor (1).

9. The flame-retardant and fire-resistant cable for rail transit according to claim 8, characterized in that, The conductor (1) is made of several strands of annealed copper wire twisted together in a 1+6+12 structure. The twisting directions of the inner and outer layers are opposite. The twisting pitch ratio of the inner layer is 10 times and the twisting pitch ratio of the outer layer is 8 times.

10. The flame-retardant and fire-resistant cable for rail transit according to claim 8, characterized in that, The protective layer (11) is configured as a three-layer co-extruded layer consisting of a conductor shielding layer, an insulation layer, and an insulation shielding layer, formed by a co-extrusion process.

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