Rail transit B1-level internal shielding railway digital signal cable

Abstract

The utility model discloses a rail transit B1-level inner shielding railway digital signal cable, which comprises a cable core, an inner sealing wrapping tape, a drain wire, a shielding wrapping tape, an outer sealing wrapping tape, an oxygen barrier layer, an isolation inner sheath, an inner cooling fireproof layer, a compression-resistant wrapping tape, an outer cooling fireproof layer and a flame-retardant outer sheath, the inner sealing wrapping tape, the shielding wrapping tape and the outer sealing wrapping tape are sequentially and longitudinally wrapped outside the cable core from inside to outside, the drain wire is longitudinally placed between the inner sealing wrapping tape and the shielding wrapping tape, the oxygen isolation layer is extruded outside the outer sealing wrapping tape, the isolation inner sheath is extruded outside the oxygen isolation layer, the compression-resistant wrapping tape is wrapped outside the isolation inner sheath, and the outer sealing wrapping tape is wrapped outside the compression-resistant wrapping tape. The isolation inner sheath is extruded outside the compression-resistant wrapping tape, the flame-retardant outer sheath is extruded outside the compression-resistant wrapping tape, the inner cooling fireproof layer is filled between the isolation inner sheath and the compression-resistant wrapping tape, and the outer cooling fireproof layer is filled between the compression-resistant wrapping tape and the flame-retardant outer sheath, so that B1-level flame-retardant capability can be achieved, and the cable also has good signal transmission capability.

Description

Technical Field

[0001] The utility model relates to the technical field of cables, in particular to the technical field of railway digital signal cables. Background Art

[0002] Flame-retardant cables refer to cables that, when burned under specified test conditions and after the test fire source is removed, can limit the spread of flames to a limited range, and at the same time, make the residual flames or residual burning extinguish themselves within a limited time. In layman's terms, even if a fire occurs, flame-retardant cables can limit combustion to a local area, prevent the spread of flames, save other equipment, and prevent greater losses.

[0003] According to the flame retardant ability under fire conditions, flame retardant cables can be divided into Class A flame retardant cables, Class B flame retardant cables and Class C flame retardant cables from high to low; among them, Class A flame retardant cables can extinguish themselves when a fire occurs, will not breed flames, and will not continue to burn, such as the Class A flame retardant cable with publication number CN106531299A; Class B flame retardant cables can slow down the burning speed and fire of the cables, effectively preventing the spread of fire, such as a low-smoke halogen-free Class B flame retardant and fire-resistant cable with announcement number CN214336430U; Class C flame retardant cables can extinguish themselves in a short time under fire conditions, effectively preventing the spread of fire, such as a Class C flame retardant power cable with announcement number CN214377785U.

[0004] However, during large-scale fires, flame temperatures typically reach approximately 750°C (or even 950°C). At this point, the structure and material temperature resistance of Class A, B, and C flame-retardant cables burning in bundles are no longer adequate, making them very easily burned. The burned residue is also very brittle (easily falling off with a slight touch or vibration, unable to effectively prevent the flame or temperature from burning and transmitting internally, making it difficult to protect the inner insulation layer with poor flame retardancy). This can cause the insulation layer to burn (because the insulation layer is mostly made of flammable organic matter), ultimately causing the entire cable to continue burning, releasing large amounts of heat and smoke, making it impossible to guarantee fire safety. Summary of the Invention

[0005] The purpose of this utility model is to solve the problems in the existing technology and propose a rail transit B1 level internal shielded railway digital signal cable, which not only can achieve B1 level flame retardancy, but also has good signal transmission capability, and is very suitable for light rail and subway and other crowded places and places requiring special protection.

[0006] To achieve the above-mentioned objectives, the present invention proposes a rail transit B1-level internally shielded railway digital signal cable, comprising a cable core, an inner sealing tape, a drain line, a shielding tape, an outer sealing tape, an oxygen barrier layer, an isolation inner sheath, an inner cooling and fireproof layer, a pressure-resistant tape, an outer cooling and fireproof layer, and a flame-retardant outer sheath. The inner sealing tape, the shielding tape, and the outer sealing tape are longitudinally wrapped around the cable core from the inside to the outside, the drain line is longitudinally placed between the inner sealing tape and the shielding tape, the oxygen barrier layer is extruded around the outer sealing tape, the isolation inner sheath is extruded around the oxygen barrier layer, the pressure-resistant tape is wrapped around the isolation inner sheath, the flame-retardant outer sheath is extruded around the pressure-resistant tape, the inner cooling and fireproof layer is filled between the isolation inner sheath and the pressure-resistant tape, and the outer cooling and fireproof layer is filled between the pressure-resistant tape and the flame-retardant outer sheath.

[0007] Preferably, the cable core is a quad-wire group formed by twisting four insulating single wires, and the wire group pitch is 100-300 mm, and marking ribbons of different colors are respectively wrapped around the four insulating single wires.

[0008] Preferably, the inner sealing tape and the outer sealing tape are both non-hygroscopic tapes.

[0009] Preferably, the drain wire is a copper wire with an outer diameter of 0.3 to 0.5 mm.

[0010] Preferably, the shielding tape is a corrugated copper tape and the corrugation depth is controlled at 0.4 to 0.6 mm.

[0011] Preferably, the oxygen-isolating layer is an alkali-free glass fiber layer.

[0012] Preferably, the insulating inner sheath is an aluminum sheath with a thickness of 1.0 to 1.5 mm.

[0013] Preferably, the compression-resistant strap is formed by wrapping a double steel strap with a thickness of 0.4 to 0.6 mm and the gap ratio is controlled within 48%.

[0014] Preferably, the inner cooling fireproof layer and the outer cooling fireproof layer are both inorganic mineral metal hydrate fireproof layers, and the inner cooling fireproof layer and the outer cooling fireproof layer are both in the form of porous meshes.

[0015] Preferably, the flame-retardant outer sheath is a ceramic low-smoke halogen-free flame-retardant polyolefin sheath with a thickness of 1.5 to 2.5 mm.

[0016] Beneficial effects of the utility model:

[0017] 1) The multi-layer flame-retardant design, with an inner layer absorbing heat and cooling and an outer layer of ceramic fire insulation, prevents flames from directly penetrating the cable during combustion. This effectively reduces the amount of combustible material burned, the total amount of heat released, and the heat release rate. It has a strong self-extinguishing ability, preventing the flame from spreading inwards. Its crusting properties can be used to prevent dripping, and it maintains low toxicity and smoke characteristics during a fire, making it less likely to cause secondary harm to the human body.

[0018] 2) By twisting four insulated single wires at a special pitch to form a quad as the cable core, the quad's anti-crosstalk performance can be improved, enabling multiple uses of one cable (i.e., simultaneous transmission at the same frequency and on the same cable, capable of transmitting 2Mbit railway digital signals, system control information, and power at a rated voltage of 750V or DC 1000V and below), meeting high driving safety requirements and suitable for connecting relevant equipment and control devices in rail transit signal systems where crowds are dense and special protection is required;

[0019] 3) By longitudinally wrapping two layers of non-hygroscopic tape outside the cable core as inner sealing tape and outer sealing tape respectively, and longitudinally wrapping corrugated copper tape and placing copper wire between the inner sealing tape and the outer sealing tape, the cable core can be effectively prevented from being loose, while taking into account high shielding, anti-interference and high strength.

[0020] The features and advantages of the present invention will be described in detail through embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a cross-sectional view of the utility model of the rail transit B1 grade internally shielded railway digital signal cable;

[0022] Figure 2 The utility model is a schematic diagram of the assembly of a cable core, an inner sealing tape, a drain wire, a shielding tape and an outer sealing tape of a rail transit B1-level inner shielded railway digital signal cable.

[0023] In the figure: 1-cable core, 2-inner sealing tape, 3-leakage line, 4-shielding tape, 5-outer sealing tape, 6-oxygen barrier layer, 7-isolation inner sheath, 8-inner cooling and fireproof layer, 9-pressure-resistant tape, 10-outer cooling and fireproof layer, 11-flame-retardant outer sheath. DETAILED DESCRIPTION

[0024] See Figure 1 and Figure 2The utility model of rail transit B1 grade internal shielded railway digital signal cable includes a cable core 1, an inner sealing tape 2, a drain line 3, a shielding tape 4, an outer sealing tape 5, an oxygen barrier layer 6, an isolation inner sheath 7, an inner cooling and fireproof layer 8, a pressure-resistant tape 9, an outer cooling and fireproof layer 10 and a flame-retardant outer sheath 11. The inner sealing tape 2, the shielding tape 4 and the outer sealing tape 5 are longitudinally wrapped around the cable core 1 from the inside to the outside, and the drain line 3 is longitudinally placed inside. Between the sealing tape 2 and the shielding tape 4, the oxygen insulation layer 6 is extruded outside the outer sealing tape 5, the isolation inner sheath 7 is extruded outside the oxygen insulation layer 6, the pressure-resistant tape 9 is wrapped outside the isolation inner sheath 7, the flame-retardant outer sheath 11 is extruded outside the pressure-resistant tape 9, the inner cooling and fireproof layer 8 is filled between the isolation inner sheath 7 and the pressure-resistant tape 9, and the outer cooling and fireproof layer 10 is filled between the pressure-resistant tape 9 and the flame-retardant outer sheath 11.

[0025] The cable core 1 is a quad-wire group formed by twisting four insulated single wires with a wire group pitch of 100 to 300 mm. Different colored marking ribbons are wrapped around the four insulated single wires (for example, red, green, white, and blue marking ribbons are used to distinguish units and stabilize structures). In addition, the optimized pitch design of 100 to 300 mm can further improve the anti-interference ability between the four insulated single wires, thereby improving the anti-crosstalk attenuation ability of the quad-wire group, while controlling the near-end crosstalk between groups to above 60 dB.

[0026] The inner sealing tape 2 and the outer sealing tape 5 are both non-hygroscopic tapes.

[0027] The leakage line 3 is a copper wire with an outer diameter of 0.4 mm.

[0028] The shielding tape 4 is an embossed copper tape with an embossing depth of 0.5 mm. The embossing treatment not only increases the mechanical strength and toughness of the copper tape, but also enables the copper tape to better complete the seam butt joint during the longitudinal wrapping process (avoiding gaps or misalignment).

[0029] The oxygen barrier layer 6 is an alkali-free glass fiber layer.

[0030] The insulating inner sheath 7 is an aluminum sheath with a thickness of 1.2 mm.

[0031] The compression-resistant tape 9 is formed by wrapping a double steel tape with a thickness of 0.5 mm and the gap ratio is controlled within 48%.

[0032] The inner cooling fireproof layer 8 and the outer cooling fireproof layer 10 are both inorganic mineral metal hydrate fireproof layers, and the inner cooling fireproof layer 8 and the outer cooling fireproof layer 10 are both porous mesh-shaped; specifically, the inner cooling fireproof layer 8 and the outer cooling fireproof layer 10 can both be magnesium hydroxide metal hydrate fireproof layers; such fireproof layers do not contain any combustible substances, have excellent fireproofing effects, and can absorb a large amount of heat and achieve flame retardant effects by losing water during the combustion process (when the internal temperature of the cable rises to 350°C, the magnesium hydroxide metal hydrate can gradually release the hydrate in the inner layer structure). The porous mesh structure can slow down the evaporation rate of the crystallized water molecules to a certain extent, and on the other hand, when the crystallized water molecules are completely evaporated, a porous mesh skeleton can be formed to further isolate the fire source, delay the temperature rise of the internal structure of the cable, and absorb the smoke generated during the combustion process; the internal cooling and fireproof layer 8 and the external cooling and fireproof layer 10 are made of inorganic materials, so they will not release any smoke and toxic and harmful gases when encountering high-temperature combustion, which is very safe and environmentally friendly.

[0033] The flame-retardant outer sheath 11 is a ceramic low-smoke halogen-free flame-retardant polyolefin sheath with a thickness of 2.0 mm. The material of the ceramic low-smoke halogen-free flame-retardant polyolefin sheath is generally composed of a polyolefin blended resin + a flame-retardant filler (such as aluminum hydroxide and magnesium hydroxide, etc.), such as the thermal insulation ceramic low-smoke flame-retardant cable material with publication number CN109517258A, which can form a layer of non-melting, non-combustible oxide hard shell during the combustion process to block the channel for the polymer to react with external thermal oxygen.

[0034] The above embodiments are intended to illustrate the present invention, not to limit the present invention. Any solution that is a simple transformation of the present invention falls within the scope of protection of the present invention.

Claims

1. Rail transit B1 grade internal shielded railway digital signal cable, characterized by: The invention comprises a cable core (1), an inner sealing tape (2), a drain line (3), a shielding tape (4), an outer sealing tape (5), an oxygen barrier layer (6), an isolating inner sheath (7), an inner cooling and fireproof layer (8), a pressure-resistant tape (9), an outer cooling and fireproof layer (10) and a flame-retardant outer sheath (11), wherein the inner sealing tape (2), the shielding tape (4) and the outer sealing tape (5) are longitudinally wrapped around the cable core (1) from the inside to the outside, and the drain line (3) is longitudinally placed between the inner sealing tape (2) and the shielding tape. (4), the oxygen-isolating layer (6) is extruded outside the outer sealing tape (5), the insulating inner sheath (7) is extruded outside the oxygen-isolating layer (6), the pressure-resistant tape (9) is wrapped outside the insulating inner sheath (7), the flame-retardant outer sheath (11) is extruded outside the pressure-resistant tape (9), the inner cooling and fireproofing layer (8) is filled between the insulating inner sheath (7) and the pressure-resistant tape (9), and the outer cooling and fireproofing layer (10) is filled between the pressure-resistant tape (9) and the flame-retardant outer sheath (11).

2. The rail transit B1 class inner shielded railway digital signal cable according to claim 1, characterized in that: The cable core (1) is a four-wire group formed by twisting four insulating single wires, and the wire group pitch is 100-300 mm. Marking ribbons of different colors are respectively wound around the four insulating single wires.

3. The rail transit B1 class inner shielded railway digital signal cable according to claim 1, characterized in that: The inner sealing tape (2) and the outer sealing tape (5) are both non-hygroscopic tapes.

4. The rail transit B1 class inner shielded railway digital signal cable according to claim 1, characterized in that: The leakage line (3) is a copper wire with an outer diameter of 0.3 to 0.5 mm.

5. The rail transit B1 class inner shielded railway digital signal cable according to claim 1, characterized in that: The shielding tape (4) is a corrugated copper tape and the corrugation depth is controlled to be 0.4-0.6 mm.

6. The rail transit B1 class inner shielded railway digital signal cable according to claim 1, characterized in that: The oxygen-isolating layer (6) is an alkali-free glass fiber layer.

7. The rail transit B1 class inner shielded railway digital signal cable according to claim 1, characterized in that: The isolation inner sheath (7) is an aluminum sheath with a thickness of 1.0 to 1.5 mm.

8. The rail transit B1 class inner shielded railway digital signal cable according to claim 1, characterized in that: The compression-resistant wrapping tape (9) is formed by wrapping a double steel strip with a thickness of 0.4 to 0.6 mm, and the gap ratio is controlled within 48%.

9. The rail transit B1 class inner shielded railway digital signal cable according to claim 1, characterized in that: The inner cooling fireproof layer (8) and the outer cooling fireproof layer (10) are both inorganic mineral metal hydrate fireproof layers, and the inner cooling fireproof layer (8) and the outer cooling fireproof layer (10) are both in the form of porous meshes.

10. The rail transit B1 class inner shielded railway digital signal cable according to claim 1, characterized in that: The flame-retardant outer sheath (11) is a ceramic low-smoke halogen-free flame-retardant polyolefin sheath with a thickness of 1.5 to 2.5 mm.

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