Flexible composite cable for rail transit and preparation method thereof

Abstract

The invention relates to the technical field of composite cables for rail transit, and provides a flexible composite cable for rail transit and a preparation method thereof.The preparation method comprises the steps that a power transmission unit, a signal transmission unit and PBO fiber bundles are constructed into a three-dimensional transmission network framework which is in a hollow tube shape as a whole through three-dimensional weaving; a plurality of upgrading channel pipes are arranged on the inner side of the three-dimensional transmission network framework, and the outer side of the three-dimensional transmission network framework is sequentially coated with a shielding layer and an outer protection layer from inside to outside. According to the flexible composite cable for the rail transit and the preparation method of the flexible composite cable, power transmission and signal transmission can be integrated, meanwhile, the overall anti-pressure capability, flexibility and anti-torsion stability are improved, the integrity of electrical connection and optical paths is effectively protected, the cost and upgrading complexity of the whole life cycle are remarkably reduced, and the service life of the cable is prolonged. And flexibility is provided for long-term technical evolution of a rail transit system, and reliable electromagnetic interference protection capability is maintained.

Description

Technical Field

[0001] This invention relates to the field of composite cable technology for rail transit, and in particular to a flexible composite cable for rail transit and its preparation method. Background Technology

[0002] With the rapid development of my country's rail transit industry, especially the continuous increase in operating speed and the increasingly complex operating environment of high-speed railways, subways, and light rail systems, the performance requirements for composite cables—the core components for vehicle power supply and information transmission—are also constantly increasing. Traditional rail transit cables generally employ separate laying methods for power cables, control cables, and communication cables. This approach not only occupies a large space and is complex to install and maintain, but also fails to meet the urgent needs of modern rail vehicles for lightweight design, high integration, and intelligence. Therefore, composite cables that integrate multiple functional units have emerged, becoming the key to solving the aforementioned problems.

[0003] In practical applications, existing composite cables used in rail transit systems have the following shortcomings in structural design and performance: Firstly, most existing composite cables adopt a "central reinforcement-concentric stranding" structure. This structure concentrically strands functional components such as power units and signal units around a central load-bearing element. While this provides a certain degree of static stability, the high structural rigidity limits the minimum bending radius to 15 to 20 times the cable's outer diameter, severely restricting the flexibility and convenience of wiring within the confined space of a vehicle. Especially under dynamic conditions such as continuous vibrations, frequent bends, and significant relative movements at carriage connections generated by rail vehicle operation, repeated bending stress can easily lead to relative displacement and friction between internal units, resulting in insulation wear, unstable signal transmission, and even unit breakage. When the stranded structure bends, the outer units bear excessive tensile stress while the inner units may undergo compressive deformation. This uneven stress distribution significantly affects the cable's bending fatigue life, making it difficult to meet the stringent durability requirements of rail transit, which involve decades and millions of bending cycles.

[0004] Secondly, the "one-time" fixed design of existing composite cables poses a serious obstacle to subsequent upgrades and functional expansions. Traditional composite cables permanently integrate all functional units (such as power lines, signal lines, and optical fibers) within a single sheath during manufacturing, forming a closed and fixed system. When the rail transit system is upgraded and new transmission lines (such as higher bandwidth optical fibers, additional sensor lines, or new control buses) are needed, the only solution is to re-lay the entire cable. This process is not only costly and time-consuming, but also extremely difficult to implement for lines already in operation, and may even lead to operational disruptions. This inherent non-upgradeability greatly limits the flexibility of rail transit systems to smoothly evolve and upgrade their capabilities as technology advances.

[0005] Furthermore, when subjected to radial pressure, the stranded structure experiences external force first on the outermost layer and then propagates inwards layer by layer. This can easily lead to permanent deformation or damage to the inner layers, especially the vulnerable signal transmission and fiber optic units. Although some cables use steel tape armor to enhance their compressive strength, this inevitably sacrifices the cable's flexibility and lightweight characteristics. In the complex application scenarios of rail transit, cables may face risks such as compression and trampling during laying, as well as accidental impacts from equipment components during operation. Their insufficient compressive strength directly threatens the long-term reliability and safety of the entire transmission system.

[0006] Chinese patent CN216212521U discloses a multifunctional optoelectronic composite cable for rail transit vehicles. This design employs a layered concentric structure, with an optical unit as the cable core, sequentially covered by a heat insulation layer, an electrical unit, and a heat dissipation fiber unit, and finally extruded with an outer sheath. Through material combination and functional partitioning, it achieves composite transmission of electrical, signal, and optical signals. However, the biggest drawback of this design in practical applications is that, despite using a flexible conductor, the layered concentric structure of "optical unit-heat insulation layer-electrical unit" experiences shear stress between layers during bending, easily leading to structural deformation and stress concentration. The overall structure lacks effective anti-bending fatigue design, making it difficult to meet the high-frequency, small-radius bending requirements of long-term operation in rail transit vehicles.

[0007] Therefore, how to provide a composite cable for rail transit that achieves excellent flexibility, convenient upgradeability, and mechanical protection capabilities while ensuring electrical performance and reliability has become an urgent technical problem to be solved. Summary of the Invention

[0008] In view of this, in order to overcome the shortcomings of the prior art, the present invention aims to provide a flexible composite cable for rail transit and a method for preparing the same.

[0009] According to one aspect of the present invention, a method for preparing a flexible composite cable for rail transit is provided. The method includes: constructing a three-dimensional transmission network skeleton in which a power transmission unit, a signal transmission unit, and a PBO fiber bundle are integrated into a hollow tubular shape by three-dimensional weaving; setting multiple upgrade channel tubes inside the three-dimensional transmission network skeleton; and covering the outer side of the three-dimensional transmission network skeleton with a shielding layer and an outer sheath layer from the inside out.

[0010] Optionally, in the method for preparing the flexible composite cable for rail transit of the present invention, multiple bundles of PBO fibers are uniformly arranged coaxially at a helical angle of 8° as a braided tendon, and multiple power transmission units, signal transmission units, and multiple bundles of PBO fibers are interwoven on the PBO fiber bundles serving as the braided tendon at a balanced braiding angle of 45°.

[0011] Optionally, the method for preparing the flexible composite cable for rail transit of the present invention involves twisting multiple annealed copper wires to form a basic core, twisting multiple strands of the basic core to form a power transmission conductor, and extruding an insulation layer onto the outside of the power transmission conductor to obtain a power transmission unit.

[0012] Optionally, the method for preparing the flexible composite cable for rail transit of the present invention uses concentric multi-layer stranding to twist multiple annealed copper wires into a base core. The stranding direction of each layer is opposite, and the stranding direction of the outermost layer is clockwise. The helical pitch of each layer increases sequentially from the inside to the outside and is 11-14 times the outer diameter of that layer.

[0013] Optionally, the method for preparing the flexible composite cable for rail transit of the present invention involves twisting multiple basic core strands into a power transmission conductor using counterclockwise single-layer stranding, with the stranding helix pitch being 17-25 times the outer diameter of the power transmission conductor.

[0014] Optionally, in the method for preparing the flexible composite cable for rail transit of the present invention, the signal transmission unit is composed of a tight-buffered optical fiber, a PBO fiber bundle spirally arranged outside the tight-buffered optical fiber, and an optical fiber sheath covering the tight-buffered optical fiber and the PBO fiber bundle.

[0015] Optionally, in the preparation method of the flexible composite cable for rail transit of the present invention, the upgraded channel tube is made of polytetrafluoroethylene material and is discretely and parallelly arranged in the hollow cavity inside the three-dimensional transmission network skeleton.

[0016] Optionally, the method for preparing the flexible composite cable for rail transit of the present invention uses copper-clad polyimide tape to overlap and cover the outside of the three-dimensional transmission network skeleton at a helical angle of 45° to form a shielding layer, with an overlap rate of 50%.

[0017] Optionally, the method for preparing the flexible composite cable for rail transit of the present invention involves extruding a low-smoke, halogen-free, flame-retardant polyolefin to melt-coat the outside of the shielding layer to form an outer sheath.

[0018] According to another aspect of the present invention, a flexible composite cable for rail transit is provided, which is manufactured according to the method described above.

[0019] The flexible composite cable for rail transit and its preparation method of the present invention have the following beneficial technical effects: 1. Through the structural design of the three-dimensional transmission network skeleton, while integrating power transmission and signal transmission, radial pressure is evenly distributed throughout the entire network structure, avoiding irreversible damage caused by local stress concentration in traditional structures. Simultaneously, the tight weave structure and the high modulus properties of PBO fibers together construct a stable system that can effectively resist external compression and impact.

[0020] 2. By constructing a hollow tubular three-dimensional transmission network skeleton, the structural defects of traditional stranded composite cables are avoided. It can effectively disperse and absorb dynamic bending stress, transforming the traditional rigid structure into a flexible structure with adaptive deformation space, significantly improving flexibility and torsional stability, thereby enhancing the fatigue life of composite cables in application scenarios such as vehicle running vibration and frequent bending at the connection of carriages.

[0021] 3. By setting multiple independent polytetrafluoroethylene upgrade channel pipes in parallel within the hollow cavity of the three-dimensional transmission network skeleton, physical pathways are reserved for subsequent system function expansion, significantly reducing the cost and upgrade complexity throughout the entire life cycle, and providing flexibility for the long-term technological evolution of rail transit systems.

[0022] 4. It can effectively protect the integrity of electrical connections and optical paths, prevent performance degradation caused by mechanical movement, and maintain stable electrical continuity and reliable electromagnetic interference protection under continuous mechanical stress. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a flowchart illustrating a method for preparing a flexible composite cable for rail transit according to Embodiment 1 of the present invention. Figure 2 A structural example diagram of a flexible composite cable for rail transit prepared according to exemplary embodiment 2 of the present invention is shown. Figure 3 This is a structural example diagram of the power transmission unit prepared according to Embodiment 3 of the present invention; Figure 4 This is a structural example diagram of the power transmission conductor prepared according to Embodiment 3 of the present invention; In the diagram, 1-PBO fiber bundle of tendon, 2-Auxiliary braided PBO fiber bundle, 3-Power transmission unit, 4-Signal transmission unit, 5-Upgrade channel tube, 6-Shielding layer, 7-Outer sheath, 31-Power transmission conductor, 32-Insulation layer, 311-Basic core. Detailed Implementation

[0025] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0026] It should be noted that, in the absence of conflict, the following embodiments and features can be combined with each other; and, based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0027] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0028] Example 1 Exemplary Example 1 of the present invention provides a method for preparing a flexible composite cable for rail transit. Figure 1 This is a flowchart illustrating a method for preparing a flexible composite cable for rail transit according to Embodiment 1 of the present invention. Figure 1 As shown, the method of this embodiment is implemented in the following manner: the power transmission unit, the signal transmission unit and the PBO fiber bundle are constructed into a hollow tubular three-dimensional transmission network skeleton by three-dimensional weaving. Multiple upgrade channel tubes are set inside the three-dimensional transmission network skeleton, and a shielding layer and an outer protective layer are wrapped around the outside of the three-dimensional transmission network skeleton from the inside to the outside.

[0029] Example 2 Exemplary Example 2 of the present invention provides a method for preparing a flexible composite cable for rail transit. The method of this embodiment is implemented in the following manner: Step 1: Preparation of Power Transmission Unit Multiple annealed copper wires are twisted to form a basic core, and multiple strands of the basic core are twisted to form a power transmission conductor. An insulation layer is then extruded onto the outside of the power transmission conductor to obtain a power transmission unit.

[0030] Step 2: Preparation of Signal Transmission Unit In this embodiment, the signal transmission unit consists of a tight-buffered optical fiber, a PBO fiber bundle spirally arranged outside the tight-buffered optical fiber, and an optical fiber sheath covering the tight-buffered optical fiber and the PBO fiber bundle.

[0031] Step 3: Construction of the 3D Transmission Network Skeleton Multiple bundles of PBO fibers are evenly arranged coaxially at an 8° helical angle to form the woven tendon section. Multiple power transmission units, signal transmission units, and multiple bundles of PBO fibers are interwoven on the PBO fiber bundles that form the woven tendon section at a balanced weaving angle of 45°.

[0032] It should be noted that the PBO (poly(p-phenylenebenzodioxazole)) fiber bundle in this embodiment is prepared by assembling single PBO fibers with a diameter of 10-15 µm into a bundle. The tensile strength of the PBO fiber is not less than 5.8 GPa, the elastic modulus is not less than 270 GPa, and the density is 1.56 g / cm³. 3 It has a long-term operating temperature of not less than 300℃, a limiting oxygen index (LOI) of 68, and excellent high temperature resistance, creep resistance and dimensional stability.

[0033] Step 4: Set up the upgrade channel pipe The upgrade channel tubes are made of polytetrafluoroethylene (PTFE), and multiple upgrade channel tubes are discretely and parallelly arranged within the hollow cavity inside the three-dimensional transmission network framework. By arranging multiple independent PTFE upgrade channel tubes in parallel within the hollow cavity of the three-dimensional transmission network framework, physical pathways are reserved for future system functional expansion. This "channel-based modular" design transforms the cable from a functionally fixed, closed system into an evolvable platform. When new transmission lines (such as higher-bandwidth optical fibers, additional sensors, or control lines) are needed in the future, the entire cable does not need to be replaced; the new cable can simply be threaded through the pre-defined channels. This significantly reduces the overall lifecycle cost and upgrade complexity, providing flexibility for the long-term technological evolution of rail transit systems.

[0034] Step 5: Prepare the shielding layer A shielding layer is formed by overlapping copper-clad polyimide tape at a 45° helix angle on the outside of the three-dimensional transmission network skeleton, with an overlap rate of 50%.

[0035] Step 6: Prepare the outer protective layer The outer protective layer is formed by extruding and melting low-smoke halogen-free flame-retardant polyolefin onto the outside of the shielding layer.

[0036] Figure 2 A structural example diagram of a flexible composite cable for rail transit prepared according to exemplary embodiment 2 of the present invention is shown below. Figure 2 As shown, in this embodiment, the flexible composite cable for rail transit has multiple tendon-shaped PBO fiber bundles 1 arranged coaxially in a spiral. Multiple auxiliary braided PBO fiber bundles 2, power transmission units 3, and signal transmission units 4 are interwoven with the PBO fiber bundles that serve as braided tendons to form a three-dimensional transmission network skeleton. Multiple upgrade channel tubes 5 are arranged inside the three-dimensional transmission network skeleton, and a shielding layer 6 and an outer sheath 7 are arranged sequentially on the outside of the three-dimensional transmission network skeleton.

[0037] Example 3 Exemplary Example 3 of the present invention provides a method for preparing a flexible composite cable for rail transit. In this embodiment, the power transmission unit is prepared in the following manner: The base conductor is formed by concentric multi-layer stranding of multiple annealed copper wires, with each layer stranding in opposite directions, the outermost layer being clockwise. The helical pitch of each layer increases sequentially from the inside out and is 11-14 times the outer diameter of that layer. The power transmission conductor is formed by counter-clockwise single-layer stranding of multiple base conductors, with the helical pitch being 17-25 times the outer diameter of the power transmission conductor. An insulation layer is then extruded onto the outside of the power transmission conductor to obtain the power transmission unit. Figure 3 This is a structural example diagram of the power transmission unit prepared according to Embodiment 3 of the present invention. Figure 4 Here is a structural example diagram of the power transmission conductor prepared according to Embodiment 3 of the present invention, as shown in the figure. Figure 3 and Figure 4 As shown, the power transmission unit consists of a power transmission conductor 31 and an insulation layer 32 covering the outside of the power transmission conductor 31. The power transmission conductor 31 is composed of multiple strands of basic wire cores 311 spirally untwisted and twisted together.

[0038] Example 4 This embodiment describes the preparation of a flexible composite cable for rail transit in the following manner: Step 1: Preparation of Power Transmission Unit In this embodiment, the structural parameters of the basic conductor are shown in Table 1.

[0039] Table 1

[0040] Using TR-type soft round copper wire conforming to GB / T 3953 standard as the material, a base core was prepared by stranding according to the structural parameters in Table 1 using a GJ45 tubular stranding machine. Using an SJ400 bundle stranding machine, six strands of this base core were stranded counterclockwise around the center base core at a stranding pitch of 21 mm, resulting in a power transmission conductor with an outer diameter of 1.05 mm. A 25-type single-screw extruder was used to extrude a 0.15 mm thick cross-linked polyethylene insulation layer onto the outer side of the 1.05 mm diameter power transmission conductor. During extrusion, a vacuum sizing sleeve was used to control the outer diameter to 1.35 mm.

[0041] Step 2: Preparation of Signal Transmission Unit In this embodiment, Corning SMF-28e+ single-mode optical fiber is selected. A nylon 12 tight-buffered layer is extruded on the outer layer of the optical fiber after a primary coating to obtain a tight-buffered optical fiber with an outer diameter of 0.9 mm. A PBO fiber bundle is wound on the outer side of the tight-buffered optical fiber with a helix angle of 30° and a stranding pitch of 25 mm using an RW-24 stranding machine. A fiber sheath made of low-smoke halogen-free flame-retardant polyolefin material is then coated using a 25-type extruder to obtain a signal transmission unit with an outer diameter of 1.2 mm.

[0042] Step 3: Construction of the 3D Transmission Network Skeleton A three-dimensional transmission network skeleton was woven using an RJ-3D24 three-dimensional braiding machine. During weaving, six spindles held PBO fiber bundles as the tendon section, with a weaving helix angle of 8° and a helix pitch of 110 mm. Twenty-four spindles held power transmission units, signal transmission units, and auxiliary PBO fiber bundles to balance the 45° weaving angle and 20 mm weaving pitch on the PBO fiber bundles serving as the tendon section. In this embodiment, the PBO fiber bundles were 1500 denier with a single bundle diameter of 0.3 mm. A TSC tension control system was used to control the tension of the PBO fiber bundles at 16 ± 1 cN, the power transmission unit tension at 10 ± 1 cN, and the signal transmission unit tension at 5 ± 1 cN. By adjusting the spindle speed, the weaving density was controlled to 94%, forming a three-dimensional transmission network skeleton with an outer diameter of 8 mm and a hollow diameter of 5.3 mm.

[0043] Step 4: Set up the upgrade channel pipe Three upgrade channel tubes are discretely and parallelly arranged in the hollow cavity inside the three-dimensional transmission network skeleton, using PTFE tubes with an outer diameter of 1.2 mm and a wall thickness of 0.1 mm as upgrade channel tubes.

[0044] Step 5: Prepare the shielding layer Using an SW-12 wrapping machine, a copper-clad polyimide tape with a thickness of 0.2 mm is overlapped and laid on the outside of the three-dimensional transmission network skeleton with a spiral angle of 45° and an overlap rate of 50% to form a shielding layer.

[0045] Step 6: Prepare the outer protective layer A 75-type single-screw extruder was used to extrude low-smoke halogen-free flame-retardant polyolefin onto the outside of the shielding layer to form an outer sheath, resulting in a flexible composite cable for rail transit with an outer diameter of 9.5 mm.

[0046] Example 5 The radial pressure of the copper flexible composite cable for rail transit prepared in Example 4 was tested using an RD-20 radial pressure testing machine equipped with a digital display pressure sensor. During sample preparation, 10 sections of the finished composite cable, each 100 mm in length, were cut. The samples were placed horizontally at the center of the lower pressure plate of the testing machine, and the upper pressure plate was lowered at a uniform speed of 5 mm / min. When the pressure reached 2000 N, it was held for 10 minutes, and the compression deformation was recorded. After removing the load for 30 minutes, the permanent deformation of the sample was measured to check for damage to the internal structure of the sample.

[0047] The three-dimensional transmission network skeleton evenly distributes radial pressure throughout the entire network structure, avoiding irreversible damage caused by localized stress concentration in traditional structures. Simultaneously, the tight weave structure and the high modulus properties of PBO fibers together construct a robust system capable of effectively resisting external compression and impact. All samples exhibited an average deformation of 1.2 mm under 2000 N pressure, and an average permanent deformation of 0.15 mm after 30 minutes of load removal. The internal three-dimensional transmission network skeleton structure remained intact, with no indentations in the power transmission and signal transmission units, and no deformation in the upgrade channel tubes.

[0048] The bending performance of the copper flexible composite cable for rail transit prepared in Example 4 was tested using a DG-300 programmable bending tester equipped with an explicit bending radius adjustment device. During sample preparation, 10 sections of finished cable, each 1.5m in length, were cut and installed on the bending tester after adjustment at a standard environment of 25℃. The bending radius was set to 80mm, and the cable was subjected to ±90° reciprocating bending at a frequency of 0.5Hz. After 1000 cycles, the shielding performance of the samples was tested. After 5000 cycles, the electrical performance and structural integrity of the samples were tested.

[0049] This invention, through the construction of a hollow tubular three-dimensional transmission network skeleton, avoids the structural defects of traditional stranded composite cables. It can effectively disperse and absorb dynamic bending stress, transforming the traditional rigid structure into a flexible structure with adaptive deformation space, significantly improving flexibility and torsional stability, thereby enhancing the fatigue life of the composite cable in application scenarios such as vehicle running vibration and frequent bending at the connection of the carriage.

[0050] The three-dimensional transmission network skeleton structure of this invention effectively protects the integrity of electrical connections and optical paths, preventing performance degradation caused by mechanical movement. After 5000 bending cycles, no visible damage such as outer sheath cracking or shielding layer breakage was observed in any of the samples. After the bending test, the DC resistance change rate of the conductor in the power transmission unit was less than 2%, the insulation resistance value remained above 5.8 MΩ·km, and the fiber optic attenuation change in the signal transmission unit was <0.05 dB / km. Dissection of the samples showed that the internal three-dimensional transmission network skeleton structure remained intact. After 1000 bending cycles, the shielding layer resistance value remained within the range of 5.2 ± 0.3 mΩ, with a fluctuation rate of less than 6%, indicating that the copper-clad polyimide tape shielding layer maintained good electrical continuity under dynamic bending conditions, without shielding layer breakage or poor contact. This further confirms that the copper-clad polyimide tape shielding structure can maintain stable electrical continuity and reliable electromagnetic interference protection capabilities under continuous mechanical stress.

[0051] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a flexible composite cable for rail transit, characterized in that, The method includes: constructing a hollow tubular three-dimensional transmission network skeleton by three-dimensional weaving the power transmission unit, signal transmission unit and PBO fiber bundle; setting multiple upgrade channel tubes inside the three-dimensional transmission network skeleton; and covering the outer side of the three-dimensional transmission network skeleton with a shielding layer and an outer protective layer from the inside to the outside.

2. The method for preparing a flexible composite cable for rail transit according to claim 1, characterized in that, Multiple bundles of PBO fibers are evenly arranged coaxially at an 8° helical angle to form the woven tendon section. Multiple power transmission units, signal transmission units, and multiple bundles of PBO fibers are interwoven on the PBO fiber bundles that form the woven tendon section at a balanced weaving angle of 45°.

3. The method for preparing a flexible composite cable for rail transit according to claim 1, characterized in that, Multiple annealed copper wires are twisted to form a basic core, and multiple strands of the basic core are twisted to form a power transmission conductor. An insulation layer is then extruded onto the outside of the power transmission conductor to obtain a power transmission unit.

4. The method for preparing a flexible composite cable for rail transit according to claim 3, characterized in that, The base core is made by twisting multiple annealed copper wires together in a concentric multi-layer stranding manner. The stranding direction of each layer is opposite, and the stranding direction of the outermost layer is clockwise. The pitch of the stranding helix of each layer increases from the inside to the outside and is 11-14 times the outer diameter of the layer.

5. The method for preparing a flexible composite cable for rail transit according to claim 4, characterized in that, The multi-strand base wire cores are twisted into a power transmission conductor by counterclockwise single-layer stranding, and the twisting helix pitch is 17-25 times the outer diameter of the power transmission conductor.

6. The method for preparing a flexible composite cable for rail transit according to claim 1, characterized in that, The signal transmission unit consists of a tight-buffered optical fiber, a PBO fiber bundle spirally arranged outside the tight-buffered optical fiber, and an optical fiber sheath covering the tight-buffered optical fiber and the PBO fiber bundle.

7. The method for preparing a flexible composite cable for rail transit according to claim 1, characterized in that, The upgrade channel tubes are made of polytetrafluoroethylene and are discretely and parallelly arranged in the hollow cavity inside the three-dimensional transmission network skeleton.

8. The method for preparing a flexible composite cable for rail transit according to claim 1, characterized in that, A shielding layer is formed by overlapping copper-clad polyimide tape at a 45° helix angle on the outside of the three-dimensional transmission network skeleton, with an overlap rate of 50%.

9. The method for preparing a flexible composite cable for rail transit according to claim 1, characterized in that, The outer protective layer is formed by extruding and melting low-smoke halogen-free flame-retardant polyolefin onto the outside of the shielding layer.

10. A flexible composite cable for rail transit, characterized in that, The flexible composite cable for rail transit is manufactured according to any one of claims 1 to 9.

Images