Shielded cable and use thereof

Abstract

The application provides a shielded cable and application thereof, which comprises an insulated wire group, a composite shielding layer covering the outside of the insulated wire group, the composite shielding layer comprising a conductive metal strip layer and an elastic conductive composite material layer covering the outside of the conductive metal strip layer through a hot-pressing composite process, and the surface of the conductive metal strip layer is provided with a nanoscale conductive layer; the elastic conductive composite material layer comprises a polymer matrix and nanoscale conductive material dispersed in the polymer matrix; through the synergistic design of the conductive metal strip layer and the elastic conductive composite material layer, the breakthrough of high-frequency shielding performance is realized, the SE attenuation rate after hygrothermal aging is reduced, the mechanical reliability is improved, the overall performance of the cable in terms of the conductive performance, the shielding performance, the mechanical strength and the environmental adaptability is improved, the service life of the cable is improved, and the maintenance cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and more specifically to a shielded cable and its applications. Background Technology

[0002] With the rapid development of 5G communication, high-speed data centers, and industrial automation equipment, electromagnetic interference (EMI) has become a key challenge to the reliability of precision electronic systems. Traditional shielded cables mostly use a single metal braided layer or aluminum foil layer, which has the following drawbacks:

[0003] 1. High-frequency shielding attenuation: The shielding effectiveness (SE) of metal braided layers drops sharply in the frequency band above 30GHz due to the skin effect (e.g., in the existing technology, the SE is often below 60dB at 40GHz).

[0004] 2. Poor environmental adaptability: The metal layer is easily oxidized in humid and hot environments, and the shielding effectiveness can decrease by 10%-15%;

[0005] 3. Insufficient flexibility: Rigid metal layers are prone to microcracks in dynamic bending scenarios, leading to local shielding failure.

[0006] In existing technologies, while elastic conductive composite materials can improve flexibility, their conductivity is insufficient (surface resistance > 10Ω / sq), making them unable to meet high-frequency shielding requirements on their own. For example, current attempts to use double-layer structures in cables to meet high-frequency shielding requirements have resulted in weak adhesion between the nano-coating and the substrate, leading to SE attenuation of over 12% after damp heat aging.

[0007] The above background information is disclosed only to assist in understanding the inventive concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application, nor does it necessarily provide technical teachings. In the absence of clear evidence, the novelty and inventiveness of the above application shall be deemed to be incomplete. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention proposes a shielded cable and its application. Through the synergistic design of a conductive metal strip layer and an elastic conductive composite material layer, a breakthrough in high-frequency shielding performance is achieved, reducing the SE attenuation rate after damp heat aging and improving mechanical reliability. This results in a comprehensive improvement in the cable's conductivity, shielding performance, mechanical strength, and environmental adaptability, not only extending the cable's service life but also reducing maintenance costs.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] On one hand, the present invention provides a shielded cable, comprising:

[0011] Insulated wire assembly,

[0012] A composite shielding layer covering the outside of the insulated wire assembly, the composite shielding layer comprising: a conductive metal strip layer and an elastic conductive composite material layer covering the outside of the conductive metal strip layer by a hot-pressing composite process, wherein the surface of the conductive metal strip layer has a nanoscale conductive layer; and the elastic conductive composite material layer comprises a polymer matrix and nano-conductive materials dispersed in the polymer matrix.

[0013] This invention proposes a shielded cable and its application. Through the synergistic design of a conductive metal strip layer and an elastic conductive composite material layer, a breakthrough in high-frequency shielding performance is achieved, reducing the SE attenuation rate after damp heat aging and improving mechanical reliability. This results in a comprehensive improvement in the cable's conductivity, shielding performance, mechanical strength, and environmental adaptability, which not only extends the cable's service life but also reduces maintenance costs.

[0014] As a preferred technical solution, the nanoscale conductive layer is a nano-silver layer, and the conductive metal strip layer is a nano-silver layer tin-plated copper strip longitudinally wrapped structure, with the longitudinal overlap rate of the nano-silver layer tin-plated copper strip being 10% to 20%.

[0015] As a preferred technical solution, the nano-conductive material is carbon nanotubes, and the carbon nanotubes form a three-dimensional conductive network in the polymer matrix; the polymer matrix is ​​a silicone rubber matrix, and the carbon nanotubes account for 2% to 8% of the mass percentage in the silicone rubber matrix.

[0016] As a preferred technical solution, the insulated wire group includes: a plurality of insulated single wires, each insulated single wire including a conductor and an insulating layer covering the outside of the conductor, the conductor including: an inner conductor and an outer conductor covering the outside of the inner conductor, the surface of the inner conductor having a laser-etched microstructure.

[0017] As a preferred technical solution, the outer conductor is made of low-oxygen copper strip with a purity of ≥99.95%, and a heat diffusion layer is formed on the outside of the inner conductor to conduct heat laterally to the entire conductor.

[0018] As a preferred technical solution, the outer conductor is filled into the microstructure of the inner conductor through a hot-pressing composite process, and a metal armor layer is formed around the outer periphery of the inner conductor.

[0019] As a preferred technical solution, the hot pressing temperature of the hot pressing composite process is 130℃~170℃, and the hot pressing pressure of the hot pressing composite process is 0.5~1.1MPa.

[0020] As a preferred technical solution, the outer side of the composite shielding layer is provided with an outer sheath containing boron nitride ceramic micropowder, and the outer sheath containing boron nitride ceramic micropowder comprises the following components:

[0021] The polyurethane matrix comprises 70-80% by weight.

[0022] Boron nitride ceramic micro powder, with a mass percentage of 15% to 30%;

[0023] Silane coupling agent, with a mass percentage of 0.1% to 0.5%;

[0024] Anti-hydrolysis agent, with a mass percentage of 0.1% to 0.3%;

[0025] Antioxidant, with a mass percentage of 0.05% to 0.15%.

[0026] As a preferred technical solution, the composite shielding layer includes:

[0027] A first composite shielding layer is disposed on the outside of the insulated wire group, and a non-hygroscopic inner lining layer is provided between the first composite shielding layer and the insulated wire group.

[0028] The second composite shielding layer is disposed outside the first composite shielding layer. Between the first composite shielding layer and the second composite shielding layer, a cable core wrapping layer and a heat insulation layer are disposed in sequence. An inner padding layer and an armor layer are disposed in sequence outside the second composite shielding layer. The outer sheath containing boron nitride ceramic micro powder is disposed outside the armor layer.

[0029] On the other hand, the application of shielded cables according to any of the above in rail transit cables.

[0030] The shielded cable and its application provided by this invention have the following beneficial effects:

[0031] 1) The present invention provides a shielded cable and its application. Through the synergistic design of conductive metal strip layer and elastic conductive composite material layer, it achieves a breakthrough in high-frequency shielding performance, reduces SE attenuation rate after damp heat aging, and improves mechanical reliability. This results in a comprehensive improvement in the cable's conductivity, shielding performance, mechanical strength and environmental adaptability, which not only extends the cable's service life but also reduces maintenance costs.

[0032] 2) This invention provides a shielded cable and its application. Through the synergistic design of a conductive metal strip layer and an elastic conductive composite material layer, a total SE ≥ 71dB is achieved in the 100MHz-40GHz frequency band, achieving a breakthrough in high-frequency shielding performance. Furthermore, the attenuation rate after damp heat aging is controlled within 6%, significantly better than industry standards (typically requiring SE attenuation ≤ 15% after aging). This reduces the SE attenuation rate after damp heat aging and improves environmental adaptability. This application uses a hot-pressing composite process to coat the elastic conductive composite material layer onto the outside of the conductive metal strip layer, resulting in an interfacial shear strength of ≥ 3.5MPa between the conductive metal strip layer and the elastic conductive composite material layer, an improvement of over 40% compared to traditional adhesive bonding. This not only avoids interlayer delamination and improves mechanical reliability but also ensures a low SE attenuation rate after damp heat aging. The nanoscale conductive layer on the surface of the conductive metal strip layer reduces the skin depth, synergistically maintaining low contact resistance with the elastic conductive composite material layer, thus improving the cable's conductivity. In summary, this results in a comprehensive improvement in the cable's conductivity, shielding performance, mechanical strength, and environmental adaptability, not only extending the cable's service life but also reducing maintenance costs. Attached Figure Description

[0033] Figure 1 A schematic diagram of the structure of a shielded cable provided by the present invention;

[0034] Figure 2 A schematic diagram of the structure of a composite shielding layer for a shielded cable provided by the present invention;

[0035] Figure 3 A schematic diagram of the conductor structure of a shielded cable provided by the present invention;

[0036] Among them, 1-insulated single wire; 2-conductor; 3-insulation layer; 4-multi-wire group; 5-non-hygroscopic inner lining layer; 6-first composite shielding layer; 7-cable core wrapping layer; 8-heat insulation layer; 9-second composite shielding layer; 10-inner padding layer; 11-armoring layer; 12-outer sheath containing boron nitride ceramic micro powder; 13-conductive metal strip layer; 14-elastic conductive composite material layer; 15-inner conductor; 16-outer conductor; 17-microstructure. Detailed Implementation

[0037] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0038] like Figure 1-2 As shown, the present invention provides a shielded cable, comprising:

[0039] Insulated wire assembly,

[0040] A composite shielding layer covering the outside of the insulated wire assembly, the composite shielding layer comprising: a conductive metal strip layer 13 and an elastic conductive composite material layer 14 covered on the outside of the conductive metal strip layer 13 by a hot-pressing composite process, wherein the surface of the conductive metal strip layer 13 has a nanoscale conductive layer; and the elastic conductive composite material layer 14 comprises a polymer matrix and nano-conductive materials dispersed in the polymer matrix.

[0041] This invention proposes a shielded cable and its application. Through the synergistic design of a conductive metal strip layer and an elastic conductive composite material layer, a breakthrough in high-frequency shielding performance is achieved, reducing the SE attenuation rate after damp heat aging and improving mechanical reliability. This results in a comprehensive improvement in the cable's conductivity, shielding performance, mechanical strength, and environmental adaptability, which not only extends the cable's service life but also reduces maintenance costs.

[0042] Preferably, the hot-pressing temperature of the hot-pressing composite process is 130℃~170℃, and the hot-pressing pressure is 0.5~1.1MPa. The preferred hot-pressing temperatures are 130℃, 140℃, 150℃, 160℃, or 170℃. For space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the protection scope. The preferred hot-pressing pressure is 0.5MPa, 0.8MPa, or 1.1MPa. For space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the protection scope. The hot-pressing composite process achieves an interfacial shear strength of 3.5MPa between the conductive metal strip layer and the elastic conductive composite material layer, which is 40% higher than that of traditional adhesive bonding processes, not only avoiding interlayer delamination but also improving mechanical reliability.

[0043] Preferably, such as Figure 2 As shown, the nanoscale conductive layer is a nano-silver layer, and the conductive metal strip layer 13 is a nano-silver layer tin-plated copper strip longitudinally wrapped structure. The longitudinal overlap rate of the nano-silver layer tin-plated copper strip is 10% to 20%, preferably 10%, 15%, or 20%. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the protection scope. An overlap rate of 10% to 20% can ensure uniform conductivity while avoiding material waste caused by excessive overlap. The nano-silver layer tin-plated copper strip longitudinally wrapped structure (overlap rate of 10%-20%) of this application, combined with the multi-dimensional optimization of the nano-silver layer, enables the cable to have excellent electrical conductivity, thermal conductivity, corrosion resistance, high-temperature oxidation resistance, and mechanical reliability, thereby improving safety and reliability.

[0044] Preferably, such as Figure 2As shown, the thickness of the conductive metal strip layer 13 is 0.03-0.07 mm, and the thickness of the elastic conductive composite material layer 14 is 0.08-0.12 mm. The thickness of the conductive metal strip layer 13 is preferably 0.03 mm, 0.05 mm, or 0.07 mm. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the protection scope. The thickness of the elastic conductive composite material layer 14 is preferably 0.08 mm, 0.1 mm, or 0.12 mm. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the protection scope.

[0045] Preferably, the nano-conductive material is carbon nanotubes, and the carbon nanotubes form a three-dimensional conductive network in the polymer matrix; the polymer matrix is ​​a silicone rubber matrix, and the mass percentage of the carbon nanotubes in the silicone rubber matrix is ​​2% to 8%, preferably 2%, 5%, or 8%. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the scope of protection; the carbon nanotubes (added at 2% to 8%) form a three-dimensional conductive network in the polymer matrix, which absorbs the remaining electromagnetic energy. Its nanoscale porous structure can induce multiple reflection attenuation. From Table 1, we can observe that the total shielding effectiveness (SE) in the 100MHz-40GHz frequency band reaches 71-105dB, of which the absorption loss accounts for 40%-53%, proving that the electromagnetic wave energy absorption and multiple reflection attenuation can be further effectively achieved through the synergy of the three-dimensional conductive network. The absorption loss ratio in the high-frequency band (10-40GHz) is increased to 47%-53%, which is better than traditional metal shielding materials.

[0046] The conductive metal strip layer 13 is a longitudinally wrapped structure of nano-silver layer tin-plated copper strip. The nano-silver layer tin-plated copper strip provides metal reflection shielding, while the elastic conductive composite material layer absorbs and reflects electromagnetic waves multiple times to attenuate the electromagnetic waves, forming a composite shielding structure. The nano-silver layer tin-plated copper strip has high conductivity, while carbon nanotubes can form a three-dimensional conductive network in the silicone rubber matrix, further reducing the overall resistance. The high aspect ratio of carbon nanotubes allows them to form a through three-dimensional conductive network with low addition amount, improving the conductivity of the cable.

[0047] Preferably, such as Figure 1 and Figure 3As shown, the insulated wire group includes: a plurality of insulated single wires 1, each insulated single wire 1 including a conductor 2 and an insulating layer 3 covering the outside of the conductor 2. The conductor 2 includes: an inner conductor 15 and an outer conductor 16 covering the outside of the inner conductor 15. The surface of the inner conductor 15 is provided with a laser-etched microstructure 17. The microstructure 17 can regulate the current distribution on the surface of the conductor 2, reduce skin effect loss during high-frequency signal transmission, increase the surface area of ​​the conductor 2, and improve heat dissipation efficiency.

[0048] Preferably, the outer conductor 16 is made of low-oxygen copper strip with a purity of ≥99.95%, forming a heat diffusion layer on the outside of the inner conductor 15 to conduct heat laterally to the entire conductor 2; the high-purity copper (conductivity ≥58MS / m) forms a continuous heat conduction path, which can quickly homogenize the hot spot temperature of the inner conductor 15, and reduce the steady-state temperature rise by more than 20% compared with ordinary copper conductors; the low-oxygen copper strip is used as a heat diffusion layer, and the heat is conducted laterally to the whole (copper thermal conductivity 398W / m·K), avoiding the accelerated aging of the insulation layer at high temperature points.

[0049] Preferably, such as Figure 3 As shown, the outer conductor 16 is filled into the microstructure 17 of the inner conductor 15 through a hot-pressing composite process, and forms a metal armor layer around the outer periphery of the inner conductor 15. The hot-pressing temperature of the hot-pressing composite process is 130℃~170℃, and the hot-pressing pressure of the hot-pressing composite process is 0.5~1.1MPa. The preferred hot-pressing temperature of the hot-pressing composite process is 130℃, 140℃, 150℃, 160℃, or 170℃. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the protection scope. The preferred hot-pressing pressure is 0.5MPa, 0.8MPa, or 1.1MPa. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the protection scope. This process resists bending stress, prevents the propagation of cracks at the edge of the microstructure 17, increases tensile strength by 40%, and extends fatigue life by 5 times.

[0050] Preferably, such as Figure 3 As shown, the microstructure 17 is a laser-etched microgroove extending axially along the outer surface of the inner conductor 15. The depth of the microgroove is 8–12 μm, and the width of the microgroove is 18–22 μm. The depth of the microgroove is preferably 8 μm, 10 μm, or 12 μm. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the protection scope. The width of the microgroove is preferably 18 μm, 20 μm, or 22 μm. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the protection scope. The microgroove can regulate the current distribution on the conductor surface, reduce skin effect loss during high-frequency signal transmission, increase the conductor surface area, and improve heat dissipation efficiency.

[0051] Preferably, such as Figure 1 As shown, the composite shielding layer is provided with an outer sheath 12 containing boron nitride ceramic micropowder on the outside. The outer sheath 12 containing boron nitride ceramic micropowder includes the following components:

[0052] The polyurethane matrix comprises 70-80% by weight.

[0053] Boron nitride ceramic micro powder, with a mass percentage of 15% to 30%;

[0054] Silane coupling agent, with a mass percentage of 0.1% to 0.5%;

[0055] Anti-hydrolysis agent, with a mass percentage of 0.1% to 0.3%;

[0056] Antioxidant, with a mass percentage of 0.05% to 0.15%;

[0057] This gives the cable excellent thermal conductivity, temperature resistance, abrasion resistance, and environmental durability, meeting the high-quality requirements of the harsh railway environment and extending the cable's service life.

[0058] Preferably, the composite shielding layer comprises:

[0059] A first composite shielding layer 6 is disposed on the outside of the insulated wire group, and a non-hygroscopic inner lining layer 5 is provided between the first composite shielding layer 6 and the insulated wire group.

[0060] The second composite shielding layer 9 is disposed outside the first composite shielding layer 6. The first composite shielding layer 6 and the second composite shielding layer 9 are sequentially provided with a cable core wrapping layer 7 and a heat insulation layer 8. The second composite shielding layer 9 is sequentially provided with an inner padding layer 10 and an armor layer 11 outside the second composite shielding layer 9. The outer sheath 12 containing boron nitride ceramic micro powder is disposed outside the armor layer 11.

[0061] The non-hygroscopic inner liner 5 includes: an extruded non-hygroscopic insulation layer or a wrapped non-hygroscopic insulation layer, which can effectively maintain the stability of the multi-wire group structure, protect the insulated wire core from mechanical damage, and provide additional electrical isolation.

[0062] This invention provides a method for manufacturing a shielded cable, comprising the following steps:

[0063] S1 uses a wire drawing process to draw the original copper rod into a copper conductor that meets the technical requirements, resulting in the inner conductor 15;

[0064] S2 uses laser etching to etch microstructure 17 on the surface of the inner conductor, and then uses a low-oxygen copper strip to coat the inner conductor 15 to form the outer conductor 16 through a hot-pressing composite process.

[0065] S3 extrudes and coats the outer conductor 16 with an insulating layer 3, thus completing the fabrication of the insulated single wire 1.

[0066] S4 uses a high-speed star twister to twist multiple insulated single wires of different colors into a wire group;

[0067] The S5 online assembly is wrapped with a non-hygroscopic inner liner 5 using a wrapping or extrusion process. Then, a first composite shielding layer 6 is wrapped over the non-hygroscopic inner liner 5 to complete the fabrication of the multi-line assembly 4.

[0068] S6, according to requirements, uses a high-speed cabling machine to twist together several multi-wire groups 4 to form a cable core.

[0069] S7 consists of a cable core wrapping layer 7, a heat insulation layer 8, a second composite shielding layer 9, an inner padding layer 10, an armor layer 11, and an outer sheath 12 containing boron nitride ceramic powder, sequentially wrapped around the cable core to obtain a shielded cable.

[0070] This invention proposes a method for manufacturing shielded cables. Through the synergistic design of conductive metal strip layers and elastic conductive composite material layers, a breakthrough in high-frequency shielding performance is achieved, reducing the SE attenuation rate after damp heat aging and improving mechanical reliability. This results in a comprehensive improvement in the cable's conductivity, shielding performance, mechanical strength, and environmental adaptability, which not only extends the cable's service life but also reduces maintenance costs.

[0071] On the other hand, the application of shielded cables according to any of the above in rail transit cables.

[0072] Example 1

[0073] This invention provides a shielded cable, comprising: an insulated wire assembly, the insulated wire assembly comprising: four insulated single wires 1 of different colors, each insulated single wire 1 comprising a conductor 2 and an insulating layer 3 covering the outside of the conductor 2, the conductor 2 comprising: an inner conductor 15 and an outer conductor 16 covering the outside of the inner conductor 15, the surface of the inner conductor 15 having a laser-etched microstructure 17, the microstructure 17 being a laser-etched microgroove extending axially along the outer surface of the inner conductor 15, the microgroove having a depth of 10 μm and a width of 20 μm; the outer conductor 16 is made of low-oxygen copper strip with a purity of 99.95%, and a heat diffusion layer is formed on the outside of the inner conductor 15 for... Heat is conducted laterally to the entire conductor; the outer conductor 16 is filled into the microstructure 17 of the inner conductor 15 through a hot-pressing composite process, and covers the outer periphery of the inner conductor 15 to form a metal armor layer. The hot-pressing temperature of the hot-pressing composite process is 160℃, and the hot-pressing pressure is 0.5Mpa; the outer side of the insulated wire group is provided with a non-hygroscopic inner lining layer 5 and a first composite shielding layer 6 from the inside to the outside to form a multi-wire group 4. The non-hygroscopic inner lining layer 5 is preferably a non-hygroscopic insulation layer wrapped around the wire. Two multi-wire groups 4 are twisted together to form a cable core. The outer side of the cable core is provided with a cable core wrapping layer 7, a heat insulation layer 8, a second composite shielding layer 9, an inner padding layer 10, an armor layer 11, and a nitrogen-containing layer from the inside to the outside. The outer sheath 12 of the boron ceramic micro powder; the first composite shielding layer 6 and the second composite shielding layer 9 both include: a conductive metal strip layer 13 and an elastic conductive composite material layer 14 coated on the outside of the conductive metal strip layer 13 by a hot-pressing composite process, wherein the hot-pressing temperature of the hot-pressing composite process is 150℃ and the hot-pressing pressure is 0.8 MPa; the surface of the conductive metal strip layer 13 has a nanoscale conductive layer, the elastic conductive composite material layer 14 includes a polymer matrix and nanoscale conductive materials dispersed in the polymer matrix, the nanoscale conductive layer is a nanoscale silver layer, and the conductive metal strip layer 13 has a longitudinally wrapped structure of nanoscale silver layer tin-plated copper strip, the longitudinal wrapping of the nanoscale silver layer tin-plated copper strip... The overlap rate is 10%, the thickness of the conductive metal strip layer 13 is 0.05 mm, and the thickness of the elastic conductive composite material layer 14 is 0.1 mm; the nano-conductive material is carbon nanotubes, and the carbon nanotubes form a three-dimensional conductive network in the polymer matrix; the polymer matrix is ​​a silicone rubber matrix, and the carbon nanotubes account for 5% of the mass percentage in the silicone rubber matrix; the outer sheath containing boron nitride ceramic micropowder is composed of the following components by mass percentage: polyurethane matrix: 74.4%, boron nitride ceramic micropowder: 25%, silane coupling agent: 0.3%, anti-hydrolysis agent (carbodiimide): 0.2%, and antioxidant 1010: 0.1%.

[0074] Example 2

[0075] The technical solution is the same as in Example 1, except that the longitudinal overlap rate of the nano-silver layer tin-plated copper strip is 15%.

[0076] Example 3

[0077] The technical solution is the same as in Example 1, except that the longitudinal overlap rate of the tin-plated copper strip with nano-silver layer is 20%.

[0078] Example 4

[0079] The technical solution is the same as that in Example 1, except that the boron nitride ceramic micro powder added to the outer sheath containing boron nitride ceramic micro powder is 15% by mass.

[0080] Example 5

[0081] The technical solution is the same as that in Example 1, except that the boron nitride ceramic micro powder added to the outer sheath containing boron nitride ceramic micro powder is 30% by mass.

[0082] Comparative Example 1

[0083] The technical solution is the same as that in Embodiment 1, except that the conductive metal strip layer is a common tin-plated copper strip longitudinally wrapped structure.

[0084] Comparative Example 2

[0085] The technical solution is the same as that in Embodiment 2, except that the conductive metal strip layer is a common tin-plated copper strip longitudinally wrapped structure.

[0086] Comparative Example 3

[0087] The technical solution is the same as that in Example 3, except that the conductive metal strip layer is a common tin-plated copper strip longitudinally wrapped structure.

[0088] Comparative Example 4

[0089] The technical solution is the same as that in Embodiment 1, except that the surface of the inner conductor does not have laser-etched microstructures.

[0090] Comparative Example 5

[0091] The technical solution is the same as that in Example 1, except that the outer sheath is composed of the following components by mass percentage: polyurethane matrix: 100%.

[0092] The test data of the shielding effectiveness and shielding effectiveness attenuation performance after damp heat aging of the shielded cable provided in Embodiment 1 of this application are shown in Table 1-2 below:

[0093] Table 1. Experimental data on the shielding effectiveness of the shielded cable in Example 1.

[0094]

[0095] Table 2. Experimental data on the shielding effectiveness degradation performance of shielded cables after damp heat aging in Example 1.

[0096]

[0097] From Table 1, we can observe that the conductive metal strip layer of this application provides a continuous conductive path. Its surface nanoscale conductive layer fills the microscopic gaps in the metal strip to form a low-impedance shielding layer. The synergistic elastic conductive composite material layer (polymer matrix and nano-conductive materials dispersed in the polymer matrix) maintains the conductivity of the conductive network during deformation. The shielded cable achieves a total SE ≥ 71dB in the 100MHz-40GHz frequency band, achieving a breakthrough in high-frequency shielding performance.

[0098] As can be seen from Table 2, the attenuation rate of the shielded cable after damp heat aging is controlled within 6%, which is significantly better than the industry standard (usually requiring SE attenuation ≤15% after aging), reducing the SE attenuation rate after damp heat aging; it not only improves the service life of the cable, but also reduces maintenance costs.

[0099] The test data of the conductive metal strips of Examples 1-3 and the ordinary tin-plated copper strips of Comparative Examples 1-3 (conductivity, thermal conductivity, corrosion resistance, oxidation resistance, and dynamic bending life) are shown in Tables 3-7 below:

[0100] Table 3 Electrical conductivity

[0101]

[0102] Table 4 Thermal conductivity properties

[0103]

[0104] Table 5 Corrosion resistance performance (after 96 hours of salt spray)

[0105]

[0106] Table 6 High-temperature antioxidant properties (150℃×500h)

[0107]

[0108] Table 7 Dynamic bending life (after 100,000 cycles)

[0109]

[0110] From Table 3-7, we can observe that the longitudinal wrapping structure of the tin-plated copper strip with nano-silver layer (overlap rate 10%-20%) in this application, in conjunction with the multi-dimensional optimization of the nano-silver layer, plays the following role:

[0111] The longitudinal wrapping structure of the tin-plated copper strip with a nano-silver layer (overlap rate of 10%-20%), in conjunction with the multi-dimensional optimization of the nano-silver layer, plays the following roles:

[0112] 1. Improved conductivity: The removal of the nano-silver layer in this application reduces the contact resistance by 62%, and optimizes the shielding transfer impedance to 38% of that of ordinary tin-plated copper strip at 1GHz, significantly improving the high-frequency signal transmission efficiency;

[0113] 2. Improved thermal conductivity: The axial thermal conductivity of this application is increased by 28%, and the temperature rise at 30A current carrying capacity is reduced by 15%. The synergistic thermal conductivity effect of the nano-silver layer and the tin-plated copper strip substrate effectively suppresses hot spot formation.

[0114] 3. Improved environmental resistance: The corrosion area of ​​this application after 96 hours of salt spray is less than 1% (compared to 15% for ordinary tin-plated copper strips), and the oxide layer thickness at 150℃ is only 0.05μm (compared to 1.2μm for ordinary tin-plated copper strips). The nano-silver layer blocks water and oxygen permeation and element interdiffusion (Ag-Cu diffusion ≤0.1μm).

[0115] 4. Ensuring mechanical reliability: After 100,000 bending cycles, the contact resistance of this application only increases by 5% (compared to 40% for ordinary tin-plated copper strip), there is no cracking at the lap joint, the shielding effectiveness decreases by <0.5dB, and the dynamic working condition stability is excellent.

[0116] In summary, this gives the cable excellent electrical conductivity, thermal conductivity, corrosion resistance, high-temperature oxidation resistance, and mechanical reliability, resulting in high safety and reliability.

[0117] The test data of the performance (high-frequency signal attenuation rate, skin effect loss, and heat dissipation efficiency) of the conductor with microstructure in Example 1 of this application and the conventional conductor without microstructure in Comparative Example 4 are shown in Tables 8-10 below:

[0118] Table 8 High-frequency signal attenuation rate (same cross section 4mm) 2 conductor)

[0119]

[0120] Table 9 Skin effect loss (at 1 GHz)

[0121]

[0122] Table 10 Heat dissipation efficiency (20A current, ambient temperature 25℃)

[0123]

[0124] As can be observed from Table 8, compared with traditional conductors, the conductor with microstructure in this application has a 30% reduction in attenuation rate in the 1GHz band (42.3→29.6dB / 100m), significantly improving the high-frequency signal transmission efficiency and optimizing high-frequency signal transmission.

[0125] From Table 9, we can observe that, compared with traditional conductors, the microstructure of the conductor in this application reduces the AC / DC resistance ratio from 22.9 to 15.7 by disrupting the skin effect current path, thereby reducing the proportion of skin effect loss by 15%, reducing high-frequency energy loss, and optimizing high-frequency signal transmission.

[0126] As can be observed from Table 10, compared with traditional conductors, the microstructure of the conductor in this application increases the effective heat dissipation area, increases the surface heat flux density by 30% (1250→1630W / m), reduces the steady-state temperature rise by 20% (58.2→46.5℃), and shortens the thermal time constant by 26% (210→155s), achieving rapid heat diffusion, making it suitable for high power density scenarios and improving heat dissipation efficiency.

[0127] The test data for the performance (thermal conductivity, temperature resistance, abrasion resistance, and environmental durability) of the shielded cables of Embodiments 1, 4, and 5 of this application and the shielded cable of Comparative Example 5 are shown in Tables 11-14 below:

[0128] Table 11 Thermal conductivity test of shielded cables (ISO22007-2)

[0129]

[0130] Table 12 Temperature resistance test of shielded cable in Example 1 (GB / T7141)

[0131]

[0132] Table 13 Abrasion resistance test of shielded cable in Example 1 (ISO 4649)

[0133]

[0134] Table 14 Environmental durability of shielded cable in Example 1 (simulating harsh operating conditions)

[0135]

[0136] From Tables 11-14, we can observe that when the boron nitride ceramic powder content of the shielded cable in Example 1 of this application is 25%, the thermal conductivity reaches 1.52 W / m·K (6.6 times that of Comparative Example 5), and the thermal diffusivity is 0.89 mm. 2² / s (5.8 times higher than Comparative Example 5), enabling the sheath to retain 82% elongation after aging at 150℃ for 168h (pure TPU only 38%), and increasing the heat distortion temperature to 98℃ (26℃ higher than Comparative Example 5), thus improving the thermal management performance of the shielded cable.

[0137] When the boron nitride ceramic powder content of the shielded cable in Example 1 of this application is 25%, the DIN wear is reduced by 71% (35mm³ vs 120mm³), the Taber wear is reduced by 72.5% (22mg / 1000 rpm vs 80mg / 1000 rpm), and the dynamic friction coefficient is reduced to 0.62 (27% lower than Comparative Example 5). In the oil resistance test, the volume expansion rate is <5% (25% in Comparative Example 5), and the tensile strength retains >90% after immersion in 10% H₂SO₄, thus enhancing the mechanical and environmental resistance of the shielded cable.

[0138] In summary, this gives the shielded cable excellent thermal conductivity, temperature resistance, abrasion resistance, and environmental durability, meeting the high-quality requirements of the harsh railway environment and extending the cable's service life.

[0139] It is understood that this invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are protected by this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of this invention.

Claims

1. A shielded electrical cable characterized by, The application relates to a shielded cable, which comprises the following components: an insulated wire group, a composite shielding layer wrapped outside the insulated wire group, the composite shielding layer comprising: a conductive metal strip layer and an elastic conductive composite material layer wrapped outside the conductive metal strip layer through a hot-pressing composite process, the surface of the conductive metal strip layer being provided with a nanoscale conductive layer; the elastic conductive composite material layer comprising a polymer matrix and nanoscale conductive materials dispersed in the polymer matrix; the composite shielding layer comprises: a first composite shielding layer arranged outside the insulated wire group, and a non-hygroscopic inner lining layer arranged between the first composite shielding layer and the insulated wire group; a second composite shielding layer arranged outside the first composite shielding layer, a cable core wrapping layer and a heat insulation layer being arranged between the first composite shielding layer and the second composite shielding layer in sequence, an inner cushion layer and an armor layer being arranged outside the second composite shielding layer in sequence, and an outer sheath containing boron nitride ceramic micropowder being arranged outside the composite shielding layer.

2. The shielded electrical cable of claim 1, wherein, The nanoscale conductive layer is a nanosilver layer, the conductive metal strip layer is a nanosilver layer tinned copper strip longitudinal wrapping structure, and the longitudinal wrapping overlap rate of the nanosilver layer tinned copper strip is 10%-20%.

3. The shielded electrical cable according to claim 1 or 2, characterized in that, The nanoscale conductive material is a carbon nanotube, and the carbon nanotube forms a three-dimensional conductive network in the polymer matrix; the polymer matrix is a silicone rubber matrix, and the mass percentage of the carbon nanotube in the silicone rubber matrix is 2%-8%.

4. The shielded electrical cable of claim 1, wherein, The insulated wire group comprises a plurality of insulated single wires, the insulated single wire comprising a conductor and an insulation layer wrapped outside the conductor, the conductor comprising an inner conductor and an outer conductor wrapped outside the inner conductor, and the surface of the inner conductor being provided with a laser-etched microstructure.

5. The shielded electrical cable of claim 4, wherein, The outer conductor is composed of low-oxygen copper strip with a purity of greater than or equal to 99.95%, and a heat diffusion layer is formed outside the inner conductor for laterally conducting heat to the whole conductor.

6. The shielded electrical cable of claim 4, wherein, The outer conductor is filled into the microstructure of the inner conductor through a hot-pressing composite process and wrapped outside the periphery of the inner conductor to form a metal armor layer.

7. The shielded electrical cable of claim 1 or 6, wherein, The hot-pressing temperature of the hot-pressing composite process is 130 DEG C-170 DEG C, and the hot-pressing pressure of the hot-pressing composite process is 0.5-1.1 MPa.

8. The shielded electrical cable of claim 1, wherein, The outer sheath containing boron nitride ceramic micropowder comprises the following components: a polyurethane matrix with a mass percentage of 70%-80%, boron nitride ceramic micropowder with a mass percentage of 15%-30%, a silane coupling agent with a mass percentage of 0.1%-0.5%, an anti-hydrolysis agent with a mass percentage of 0.1%-0.3%, and an antioxidant with a mass percentage of 0.05%-0.15%.

9. Application of the shielded cable according to any one of claims 1-8 in a rail transit cable.

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