Shielded cable and application thereof

Abstract

The invention provides a shielding cable and application thereof, the shielding cable comprises an insulation wire group and a composite shielding layer wrapping the insulation wire group, the composite shielding layer comprises a conductive metal belt layer and an elastic conductive composite material layer wrapping the conductive metal belt layer through a hot pressing composite technology, a nanoscale conductive layer is arranged on the surface of the conductive metal belt layer; the elastic conductive composite material layer comprises a polymer matrix and a nano conductive material dispersed in the polymer matrix; through collaborative design of the conductive metal belt layer and the elastic conductive composite material layer, high-frequency shielding performance breakthrough is realized, SE attenuation rate after damp-heat aging is reduced, mechanical reliability is improved, conductivity, shielding performance, mechanical strength and environmental adaptability of the cable are comprehensively improved, the service life of the cable is prolonged, and the service life of the cable is prolonged. And the maintenance cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of cables, and in particular to a shielded cable and applications thereof. Background Art

[0002] With the rapid development of 5G communications, 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 braid or aluminum foil layer, which has the following defects: 1. High-frequency shielding attenuation: The shielding effectiveness (SE) of the metal braid layer drops sharply in the frequency band above 30 GHz due to the skin effect (for example, in the existing technology, the SE is often less than 60 dB at 40 GHz); 2. Poor environmental adaptability: The metal layer is easily oxidized in a hot and humid environment, and the shielding effectiveness attenuation rate can reach 10%-15%; 3. Insufficient flexibility: The rigid metal layer is prone to microcracks in dynamic bending scenarios, resulting in local shielding failure.

[0003] Existing technologies, while elastic conductive composite materials can improve flexibility, lack sufficient conductivity (surface resistance >10Ω / sq), making them incapable of independently meeting high-frequency shielding requirements. For example, current attempts to meet high-frequency shielding requirements with double-layer cables have resulted in weak bonding between the nanocoating and the substrate, leading to SE degradation exceeding 12% after wet-heat aging.

[0004] The disclosure of the above background technology content is only used to assist in understanding the inventive concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application, nor does it necessarily provide technical guidance; there is no clear evidence to show the novelty and creativity of the above application. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention proposes a shielded cable and its application. Through the coordinated design of the conductive metal tape layer and the elastic conductive composite material layer, a breakthrough in high-frequency shielding performance is achieved, the SE attenuation rate after wet and hot aging is reduced, and the mechanical reliability is improved, so that the cable has comprehensive improvements in conductivity, shielding performance, mechanical strength and environmental adaptability, which not only increases the service life of the cable, but also reduces maintenance costs.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows: In one aspect, the present invention provides a shielded cable, comprising: Insulated wire set, A composite shielding layer coated on the outside of the insulated wire group comprises: a conductive metal tape layer and an elastic conductive composite material layer coated on the outside of the conductive metal tape layer by a hot pressing composite process, wherein the surface of the conductive metal tape layer has a nanoscale conductive layer; the elastic conductive composite material layer comprises a polymer matrix and nano-conductive material dispersed in the polymer matrix.

[0007] The present invention proposes a shielded cable and its application. Through the coordinated design of a conductive metal tape layer and an elastic conductive composite material layer, a breakthrough in high-frequency shielding performance is achieved, the SE attenuation rate after wet and hot aging is reduced, and the mechanical reliability is improved. The cable has a comprehensive improvement in conductivity, shielding performance, mechanical strength and environmental adaptability, which not only increases the service life of the cable but also reduces maintenance costs.

[0008] As an optimal technical solution, the nanoscale conductive layer is a nanosilver layer, the conductive metal strip layer is a nanosilver layer tinned copper strip longitudinally wrapped structure, and the longitudinal wrapping overlap rate of the nanosilver layer tinned copper strip is 10% to 20%.

[0009] 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 mass percentage of the carbon nanotubes in the silicone rubber matrix is ​​2% to 8%.

[0010] As an optimal technical solution, the insulated wire group includes: a number of insulated single wires, the insulated single wires include a conductor and an insulating layer wrapped around the outside of the conductor, the conductor includes: an inner conductor and an outer conductor wrapped around the outside of the inner conductor, and the surface of the inner conductor is provided with a laser-etched microstructure.

[0011] As a preferred technical solution, the outer conductor is made of low-oxygen copper tape 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.

[0012] As a preferred technical solution, the outer conductor is filled into the microstructure of the inner conductor through a hot pressing composite process, and is coated on the outer periphery of the inner conductor to form a metal armor layer.

[0013] As a preferred technical solution, the hot pressing temperature of the hot pressing composite process is 130° C. to 170° C., and the hot pressing pressure of the hot pressing composite process is 0.5 to 1.1 MPa.

[0014] As a preferred technical solution, an outer sheath containing boron nitride ceramic powder is provided on the outside of the composite shielding layer. The outer sheath containing boron nitride ceramic powder comprises the following components: Polyurethane matrix, the mass percentage of which is 70-80%; Boron nitride ceramic powder, the mass percentage of which is 15% to 30%; Silane coupling agent, the mass percentage of which is 0.1% to 0.5%; Anti-hydrolysis agent, the mass percentage is 0.1% to 0.3%; The weight percentage of the antioxidant is 0.05% to 0.15%.

[0015] As a preferred technical solution, the composite shielding layer includes: a first composite shielding layer, the first composite shielding layer being arranged outside the insulated wire group, and a non-hygroscopic lining layer being provided between the first composite shielding layer and the insulated wire group; A second composite shielding layer is arranged on the outside of the first composite shielding layer, a cable core tape layer and a thermal insulation layer are sequentially provided between the first composite shielding layer and the second composite shielding layer, an inner cushion layer and an armor layer are sequentially provided on the outside of the second composite shielding layer, and the outer sheath containing boron nitride ceramic powder is arranged on the outside of the armor layer.

[0016] On the other hand, the shielded cable according to any one of the above items is used in rail transit cables.

[0017] The present invention provides a shielded cable and its application, which has the following beneficial effects: 1) The present invention provides a shielded cable and its application, which achieves a breakthrough in high-frequency shielding performance through the coordinated design of a conductive metal tape layer and an elastic conductive composite material layer, reduces the SE attenuation rate after wet and hot 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 increases the cable's service life but also reduces maintenance costs.

[0018] 2) The present invention provides a shielded cable and its application. Through the coordinated design of the conductive metal tape layer and the elastic conductive composite material layer, the total SE ≥ 71dB is achieved in the 100MHz-40GHz frequency band, achieving a breakthrough in high-frequency shielding performance. The attenuation rate after wet 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 wet heat aging and improving environmental adaptability. The present application adopts a hot pressing composite process to wrap the elastic conductive composite material layer on the outside of the conductive metal tape layer, resulting in the interface shear strength of the conductive metal tape layer and the elastic conductive composite material layer reaching ≥ 3.5MPa, which is more than 40% higher than the traditional bonding process. It not only avoids interlayer delamination and improves mechanical reliability, but also ensures a low SE attenuation rate after wet heat aging. The nanoscale conductive layer on the surface of the conductive metal tape layer reduces the skin depth, and cooperates with the elastic conductive composite material layer to maintain low contact resistance, thereby improving the conductive performance of the cable. In summary, the cable has comprehensive improvements in conductivity, shielding performance, mechanical strength and environmental adaptability, which not only increases the service life of the cable but also reduces maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic structural diagram of a shielded cable provided by the present invention; Figure 2 A schematic structural diagram of a composite shielding layer of a shielded cable provided by the present invention; Figure 3 A schematic structural diagram of a conductor of a shielded cable provided by the present invention; Among them, 1-insulated single wire; 2-conductor; 3-insulating layer; 4-multi-wire group; 5-non-hygroscopic lining layer; 6-first composite shielding layer; 7-cable core tape layer; 8-thermal insulation layer; 9-second composite shielding layer; 10-inner cushion layer; 11-armor layer; 12-outer sheath containing boron nitride ceramic powder; 13-conductive metal tape layer; 14-elastic conductive composite material layer; 15-inner conductor; 16-outer conductor; 17-microstructure. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0021] like Figure 1-2 As shown, the present invention provides a shielded cable, comprising: Insulated wire set, A composite shielding layer coated on the outside of the insulated wire group comprises: a conductive metal tape layer 13 and an elastic conductive composite material layer 14 coated on the outside of the conductive metal tape layer 13 by a hot pressing composite process, wherein the surface of the conductive metal tape layer 13 has a nano-scale conductive layer; the elastic conductive composite material layer 14 comprises a polymer matrix and nano-conductive material dispersed in the polymer matrix.

[0022] The present invention proposes a shielded cable and its application. Through the coordinated design of a conductive metal tape layer and an elastic conductive composite material layer, a breakthrough in high-frequency shielding performance is achieved, the SE attenuation rate after wet and hot aging is reduced, and mechanical reliability is improved. The cable has a comprehensive improvement in conductivity, shielding performance, mechanical strength and environmental adaptability, which not only increases the service life of the cable but also reduces maintenance costs.

[0023] Preferably, 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 hot pressing temperature of the hot pressing composite process is preferably 130℃, 140℃, 150℃, 160℃ or 170℃. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the protection range; the hot pressing pressure is preferably 0.5Mpa, 0.8Mpa or 1.1MPa. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the protection range; the hot pressing composite process makes the interface shear strength between the conductive metal tape layer and the elastic conductive composite material layer reach 3.5MPa, which is 40% higher than the traditional bonding process, which not only avoids interlayer delamination but also improves mechanical reliability.

[0024] Preferably, if Figure 2 As shown, the nanoscale conductive layer is a nanosilver layer, and the conductive metal tape layer 13 is a nanosilver layer tinned copper tape longitudinally wrapped structure. The longitudinal wrapping overlap rate of the nanosilver layer tinned copper tape is 10% to 20%, and the longitudinal wrapping overlap rate of the nanosilver layer tinned copper tape is preferably 10%, 15% or 20%. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the protection scope; the overlap rate of 10% to 20% can ensure uniform conductivity while avoiding material waste caused by excessive overlap. The nanosilver layer tinned copper tape longitudinal wrapping structure (overlap rate 10%-20%) of the present application cooperates with the multi-dimensional optimization of the nanosilver layer, so that the cable has excellent electrical conductivity, thermal conductivity, corrosion resistance, high temperature oxidation resistance and mechanical reliability, thereby improving safety and reliability.

[0025] Preferably, if Figure 2 As shown, the thickness of the conductive metal tape 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 tape layer 13 is preferably 0.03 mm, 0.05 mm or 0.07 mm. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point 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 simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the protection scope.

[0026] 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 carbon nanotubes account for 2% to 8% by mass of the silicone rubber matrix. The carbon nanotubes preferably account for 2%, 5%, or 8% by mass of the silicone rubber matrix. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values ​​included in the scope of protection. The carbon nanotubes (added in an amount of 2% to 8%) form a three-dimensional conductive network in the polymer matrix, which absorbs residual electromagnetic energy through the three-dimensional conductive network. The nano-pore structure can induce multiple reflection attenuation. From Table 1, we can see that the total shielding effectiveness (SE) in the 100 MHz-40 GHz frequency band reaches 71-105 dB, of which absorption loss accounts for 40%-53%. This proves that the three-dimensional conductive network can further effectively achieve electromagnetic wave energy absorption and multiple reflection attenuation through synergy. The absorption loss in the high frequency band (10-40 GHz) is increased to 47%-53%, which is better than traditional metal shielding materials.

[0027] The conductive metal tape layer 13 is a nano-silver layer tinned copper tape longitudinally wrapped structure. The nano-silver layer tinned copper tape provides metal reflection shielding, and the elastic conductive composite material layer attenuates electromagnetic waves by absorption and multiple reflections to form a composite shielding structure. The nano-silver layer tinned copper tape has high conductivity, and 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 enables them to form a through three-dimensional conductive network at a low addition amount, thereby improving the conductivity of the cable.

[0028] Preferably, if Figure 1 and Figure 3 As shown, the insulated wire group includes: a plurality of insulated single wires 1, the insulated single wire 1 includes a conductor 2 and an insulating layer 3 coated on the outside of the conductor 2, the conductor 2 includes: an inner conductor 15 and an outer conductor 16 coated on the outside of the inner conductor 15, and 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 the skin effect loss during high-frequency signal transmission, increase the surface area of ​​the conductor 2, and improve the heat dissipation efficiency.

[0029] Preferably, the outer conductor 16 is formed of a low-oxygen copper tape with a purity of ≥99.95%, and a heat diffusion layer is formed on the outer side of the inner conductor 15 to conduct heat laterally to the entire conductor 2. High-purity copper (conductivity ≥58MS / m) forms a continuous heat conduction path, which can quickly equalize the hot spot temperature of the inner conductor 15, reducing the steady-state temperature rise by more than 20% compared with ordinary copper conductors. The low-oxygen copper tape serves as a heat diffusion layer to conduct heat laterally to the entire conductor (copper thermal conductivity coefficient 398W / m·K), preventing high temperature points from accelerating aging of the insulation layer.

[0030] Preferably, if 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 is coated on 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 130°C to 170°C, and the hot pressing pressure of the hot pressing composite process is 0.5 to 1.1 MPa. The hot pressing temperature of the hot pressing composite process is preferably 130°C, 140°C, 150°C, 160°C or 170°C. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the protection range. The hot pressing pressure is preferably 0.5 MPa, 0.8 MPa or 1.1 MPa. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the protection range. It resists bending stress, prevents cracks from expanding at the edge of the microstructure 17, increases tensile strength by 40%, and extends fatigue life by 5 times.

[0031] Preferably, if 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 to 12 um, and the width of the microgroove is 18 to 22 um; the depth of the microgroove is preferably 8 um, 10 um or 12 um. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the protection range; the width of the microgroove is preferably 18 um, 20 um or 22 um. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the protection range; the microgroove can regulate the current distribution on the surface of the conductor, reduce the skin effect loss during high-frequency signal transmission, increase the surface area of ​​the conductor, and improve the heat dissipation efficiency.

[0032] Preferably, if Figure 1 As shown, an outer sheath 12 containing boron nitride ceramic powder is provided on the outside of the composite shielding layer. The outer sheath 12 containing boron nitride ceramic powder includes the following components: Polyurethane matrix, the mass percentage of which is 70-80%; Boron nitride ceramic powder, the mass percentage of which is 15% to 30%; Silane coupling agent, the mass percentage of which is 0.1% to 0.5%; Anti-hydrolysis agent, the mass percentage is 0.1% to 0.3%; Antioxidant, the mass percentage is 0.05% to 0.15%; This makes the cable have excellent thermal conductivity, temperature resistance, wear resistance and environmental durability, meeting the high quality requirements of the harsh railway environment for cables and extending the service life of the cable.

[0033] Preferably, the composite shielding layer comprises: a first composite shielding layer 6, the first composite shielding layer 6 being arranged outside the insulated wire group, and a non-hygroscopic lining layer 5 being provided between the first composite shielding layer 6 and the insulated wire group; a second composite shielding layer 9, the second composite shielding layer 9 being arranged on the outside of the first composite shielding layer 6, a cable core tape layer 7 and a thermal insulation layer 8 being sequentially provided between the first composite shielding layer 6 and the second composite shielding layer 9, an inner cushion layer 10 and an armor layer 11 being sequentially provided on the outside of the second composite shielding layer 9, and the outer sheath 12 containing boron nitride ceramic powder being arranged on the outside of the armor layer 11; The non-hygroscopic lining layer 5 includes: an extruded non-hygroscopic insulating layer or a wrapped non-hygroscopic insulating layer, which can effectively maintain the stability of the multi-wire group structure, protect the insulated cores from mechanical damage, and provide additional electrical isolation.

[0034] The present invention provides a method for manufacturing a shielded cable, comprising the following steps: S1 uses a wire drawing process to draw the original copper rod into a copper conductor that meets technical requirements to obtain an inner conductor 15; S2 uses a laser etching process to etch a microstructure 17 on the surface of the inner conductor, and then a low-oxygen copper strip is coated on the inner conductor 15 through a hot pressing composite process to produce an outer conductor 16; S3 extrudes an insulating layer 3 over the outer conductor 16 to complete the production of the insulated single wire 1.

[0035] S4 uses a high-speed star-shaped stranding machine to strand multiple insulated single wires of different colors into a wire group; The S5 line group is coated with a non-hygroscopic inner lining layer 5 by a wrapping or extrusion process, and the non-hygroscopic inner lining layer 5 is coated with a first composite shielding layer 6 to complete the production of the multi-line group 4.

[0036] S6 uses a high-speed cabling machine to twist several multi-wire groups 4 together to form a cable core according to the needs. S7 sequentially coats the cable core with a cable core tape layer 7, a heat insulation layer 8, a second composite shielding layer 9, an inner cushion layer 10, an armor layer 11 and an outer sheath 12 containing boron nitride ceramic powder to obtain a shielded cable.

[0037] The present invention proposes a method for manufacturing a shielded cable. Through the coordinated design of a conductive metal tape layer and an elastic conductive composite material layer, a breakthrough in high-frequency shielding performance is achieved, the SE attenuation rate after wet-heat aging is reduced, and mechanical reliability is improved. This allows for comprehensive improvements in the cable's conductivity, shielding performance, mechanical strength, and environmental adaptability, thereby increasing the cable's service life and reducing maintenance costs.

[0038] On the other hand, the shielded cable according to any one of the above items is used in rail transit cables.

[0039] Example 1

[0040] The present invention provides a shielded cable, comprising: an insulated wire group, the insulated wire group comprising: four insulated single wires 1 of different colors, the insulated single wires 1 comprising a conductor 2 and an insulating layer 3 coated on the outside of the conductor 2, the conductor 2 comprising: an inner conductor 15 and an outer conductor 16 coated on the outside of the inner conductor 15, the surface of the inner conductor 15 being provided with 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 depth of the microgroove being 10 μm and the width being 20 μm; the outer conductor 16 being made of a low-oxygen copper tape with a purity of 99.95%, and forming a heat diffusion layer on the outside of the inner conductor 15 for The heat is laterally conducted to the conductor as a whole; the outer conductor 16 is filled into the microstructure 17 of the inner conductor 15 by a hot pressing composite process, and is coated on 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°C, and the hot pressing pressure is 0.5Mpa; the outside 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 wrapped non-hygroscopic insulating layer, and two multi-wire groups 4 are twisted to form a cable core, and the outside of the cable core is provided with a cable core tape layer 7, a thermal insulation layer 8, a second composite shielding layer 9, an inner pad 10, an armor layer 11 and a nitrogen-containing The outer sheath 12 of boron ceramic powder; the first composite shielding layer 6 and the second composite shielding layer 9 both include: a conductive metal tape layer 13 and an elastic conductive composite material layer 14 coated on the outside of the conductive metal tape layer 13 by a hot pressing composite process, the hot pressing temperature of the hot pressing composite process is 150°C, and the hot pressing pressure is 0.8Mpa; the surface of the conductive metal tape layer 13 has a nano-scale conductive layer, the elastic conductive composite material layer 14 includes a polymer matrix and a nano-conductive material dispersed in the polymer matrix, the nano-scale conductive layer is a nano-silver layer, the conductive metal tape layer 13 is a nano-silver layer tinned copper tape longitudinally wrapped structure, the nano-silver layer tinned copper tape longitudinally wrapped The overlap rate is 10%, the thickness of the conductive metal tape 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 mass percentage of the carbon nanotubes in the silicone rubber matrix is ​​5%; the outer sheath containing boron nitride ceramic powder is composed of the following components in the following mass percentages: polyurethane matrix: 74.4%, boron nitride ceramic powder: 25%, silane coupling agent: 0.3%, anti-hydrolysis agent (carbodiimide): 0.2% and antioxidant 1010: 0.1%.

[0041] Example 2

[0042] The technical solution is the same as that of Example 1, except that the longitudinal overlap rate of the nano-silver layer tinned copper strip is 15%.

[0043] Example 3

[0044] The technical solution is the same as that of Example 1, except that the longitudinal overlap rate of the nano-silver layer tinned copper strip is 20%.

[0045] Example 4

[0046] The technical solution is the same as that of Example 1, except that the mass percentage of boron nitride ceramic micropowder added to the outer sheath containing boron nitride ceramic micropowder is 15%.

[0047] Example 5

[0048] The technical solution is the same as that of Example 1, except that the mass percentage of boron nitride ceramic micropowder added to the outer sheath containing boron nitride ceramic micropowder is 30%.

[0049] Comparative Example 1 The technical solution is the same as that of Example 1, except that the conductive metal strip layer is a common tinned copper strip longitudinally wrapped structure.

[0050] Comparative Example 2 The technical solution is the same as that of Example 2, except that the conductive metal strip layer is a common tinned copper strip longitudinally wrapped structure.

[0051] Comparative Example 3 The technical solution is the same as that of Example 3, except that the conductive metal strip layer is a common tinned copper strip longitudinally wrapped structure.

[0052] Comparative Example 4 The technical solution is the same as that of Example 1, except that the surface of the inner conductor does not have a laser-etched microstructure.

[0053] Comparative Example 5 The technical solution is the same as that of Example 1, except that the outer sheath is composed of the following components in the following mass percentages: polyurethane matrix: 100%.

[0054] The test experimental data of the shielding effectiveness and shielding effectiveness attenuation performance after damp heat aging of the shielded cable provided in Example 1 of the present application are shown in Table 1-2 below: Table 1 Shielding effectiveness performance test data of shielded cable in Example 1

[0055] Table 2 Experimental data of shielding effectiveness attenuation performance test of shielded cable after damp heat aging in Example 1

[0056] From Table 1, we can observe that the conductive metal tape layer of the present application provides a continuous conductive path, and the nanoscale conductive layer on its surface fills the microscopic gaps in the metal tape to form a low-impedance shielding layer. The elastic conductive composite material layer (polymer matrix and nano-conductive material dispersed in the polymer matrix) cooperates to maintain the connectivity of the conductive network during deformation. The shielded cable achieves a total SE ≥ 71 dB in the 100 MHz-40 GHz frequency band, achieving a breakthrough in high-frequency shielding performance.

[0057] From Table 2, we can observe that the attenuation rate of the shielded cable of this application after damp heat aging is controlled within 6%, which is significantly better than the industry standard (usually requiring SE attenuation after aging to be ≤15%), reducing the SE attenuation rate after damp heat aging; not only does it increase the service life of the cable, but it also reduces maintenance costs.

[0058] The test data of the performance (conductivity, thermal conductivity, corrosion resistance, oxidation resistance, and dynamic bending life) of the conductive metal strip layers of Examples 1-3 of the present application and the ordinary tinned copper strips of Comparative Examples 1-3 are shown in Tables 3-7 below: Table 3 Conductive properties

[0059] Table 4 Thermal conductivity

[0060] Table 5 Corrosion resistance (after 96 hours of salt spray)

[0061] Table 6 High temperature oxidation resistance (150℃×500h)

[0062] Table 7 Dynamic bending life (after 100,000 cycles)

[0063] From Tables 3-7, we can observe that the nano-silver layer and tinned copper tape longitudinally wrapped structure (overlap ratio 10%-20%) in this application, in conjunction with the multi-dimensional optimization of the nano-silver layer, have the following effects: The nano-silver layer and tinned copper tape longitudinally wrapped structure (overlap ratio 10%-20%), in conjunction with the multi-dimensional optimization of the nano-silver layer, has the following effects: 1. Improved conductivity: The nano-silver layer in this application reduces contact resistance by 62%, and the shielding transfer impedance is optimized to 38% of that of ordinary tinned copper strip at 1GHz, significantly improving high-frequency signal transmission efficiency; 2. Improved thermal conductivity: The axial thermal conductivity of this application is increased by 28%, and the temperature rise is reduced by 15% at a current of 30A. The synergistic thermal conductivity effect of the nano-silver layer and the tinned copper strip substrate effectively suppresses the formation of hot spots. 3. Improved environmental resistance: After 96 hours of salt spray, the corrosion area of ​​this application is less than 1% (compared to 15% for ordinary tinned copper strips). The oxide layer thickness at 150°C is only 0.05μm (compared to 1.2μm for ordinary tinned copper strips). The nanosilver layer blocks water and oxygen penetration and element interdiffusion (Ag-Cu diffusion ≤ 0.1μm). 4. Guaranteed mechanical reliability: After 100,000 bending cycles, the contact resistance of this application only increases by 5% (compared to a 40% increase for ordinary tinned copper strips), the lap joints are free of cracks, the shielding effectiveness attenuation is less than 0.5dB, and the dynamic working stability is excellent; In summary, the cable has excellent electrical conductivity, thermal conductivity, corrosion resistance, high temperature oxidation resistance, mechanical reliability and other properties, and is highly safe and reliable.

[0064] The performance (high-frequency signal attenuation rate, skin effect loss, and heat dissipation efficiency) of the conductor with microstructure in Example 1 of the present application and the traditional conductor without microstructure in Comparative Example 4 are shown in Tables 8-10 below: Table 8 High frequency signal attenuation rate (same cross section 4mm 2 conductor)

[0065] Table 9 Skin effect loss (at 1 GHz)

[0066] Table 10 Heat dissipation efficiency (20A current, ambient temperature 25°C)

[0067] From Table 8, we can observe that, compared with traditional conductors, the conductor with microstructure in the present application has a 30% reduction in attenuation rate in the 1 GHz frequency band (42.3→29.6 dB / 100 m), and the high-frequency signal transmission efficiency is significantly improved, thereby optimizing high-frequency signal transmission.

[0068] From Table 9, we can observe that, compared with conventional conductors, the microstructure of the conductor of the present application reduces the AC / DC resistance ratio from 22.9 to 15.7 by destroying the skin effect current path, reduces the skin effect loss ratio by 15%, reduces high-frequency energy loss, and optimizes high-frequency signal transmission.

[0069] From Table 10, we can observe that compared with traditional conductors, the microstructure of the conductor in the present application increases the effective heat dissipation area, the surface heat flux density is increased by 30% (1250→1630W / m), the steady-state temperature rise is reduced by 20% (58.2→46.5°C), and the thermal time constant is shortened by 26% (210→155s), achieving rapid heat diffusion, suitable for high power density scenarios, and improving heat dissipation efficiency.

[0070] The test experimental data of the performance (thermal conductivity, temperature resistance, wear resistance and environmental durability) of the shielded cables of Examples 1, 4 and 5 of the present application and the shielded cable of Comparative Example 5 are shown in Tables 11-14 below: Table 11 Thermal conductivity test of shielded cable (ISO22007-2)

[0071] Table 12 Temperature resistance test of shielded cable in Example 1 (GB / T7141)

[0072] Table 13 Abrasion resistance test of shielded cable of Example 1 (ISO4649)

[0073] Table 14 Environmental durability of shielded cable of Example 1 (simulating harsh working conditions)

[0074] From Tables 11-14, we can observe that when the amount of boron nitride ceramic powder added to the shielded cable of Example 1 of the present application is 25%, the thermal conductivity is 1.52W / m·k (6.6 times that of Example 5), and the thermal diffusivity is 0.89mm 2² / s (5.8 times higher than that of comparative example 5), the elongation retention rate of the sheath after aging at 150°C for 168h reached 82% (only 38% for pure TPU), and the heat deformation temperature was increased to 98°C (26°C higher than that of comparative example 5), thus improving the thermal management performance of the shielded cable; When the boron nitride ceramic powder of Example 1 of the present application was added at a 25% concentration, DIN abrasion loss was reduced by 71% (35 mm³ vs. 120 mm³), Taber wear was reduced by 72.5% (22 mg / 1000 revolutions vs. 80 mg / 1000 revolutions), and the dynamic friction coefficient was reduced to 0.62 (a 27% decrease compared to Comparative Example 5). In the oil resistance test, the volume expansion rate was less than 5% (compared to 25% in Comparative Example 5), and the tensile strength retention after immersion in 10% H₂SO₄ was greater than 90%, demonstrating enhanced mechanical and environmental resistance of the shielded cable. In summary, the shielded cable has excellent thermal conductivity, temperature resistance, wear resistance and environmental durability, meeting the high quality requirements of the harsh railway environment for cables and extending the service life of the cable.

[0075] It will be appreciated that the present invention is described through some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are subject to various changes or equivalent substitutions. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope protected by the present invention.

Claims

1. A shielded cable, characterized in that: include: Insulated wire set, A composite shielding layer coated on the outside of the insulated wire group comprises: a conductive metal tape layer and an elastic conductive composite material layer coated on the outside of the conductive metal tape layer by a hot pressing composite process, wherein the surface of the conductive metal tape layer has a nanoscale conductive layer; the elastic conductive composite material layer comprises a polymer matrix and nano-conductive material dispersed in the polymer matrix.

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

3. The shielded cable according to claim 1 or 2, characterized in that: 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%.

4. The shielded cable according to claim 1, wherein The insulated wire group includes: a plurality of insulated single wires, each of which includes a conductor and an insulating layer covering the outside of the conductor, and the conductor includes: an inner conductor and an outer conductor covering the outside of the inner conductor, and the surface of the inner conductor is provided with a laser-etched microstructure.

5. The shielded cable according to claim 4, characterized in that The outer conductor is made of low-oxygen copper tape 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.

6. The shielded cable according to claim 4, characterized in that The outer conductor is filled into the microstructure of the inner conductor through a hot pressing composite process and is coated on the outer periphery of the inner conductor to form a metal armor layer.

7. The shielded cable according to claim 1 or 6, characterized in that: The hot pressing temperature of the hot pressing composite process is 130° C. to 170° C., and the hot pressing pressure of the hot pressing composite process is 0.5 to 1.1 MPa.

8. The shielded cable according to claim 1, wherein An outer sheath containing boron nitride ceramic powder is provided on the outside of the composite shielding layer. The outer sheath containing boron nitride ceramic powder comprises the following components: Polyurethane matrix, the mass percentage of which is 70-80%; Boron nitride ceramic powder, the mass percentage of which is 15% to 30%; Silane coupling agent, the mass percentage of which is 0.1% to 0.5%; Anti-hydrolysis agent, the mass percentage is 0.1% to 0.3%; The weight percentage of the antioxidant is 0.05% to 0.15%.

9. The shielded cable according to claim 8, characterized in that The composite shielding layer comprises: a first composite shielding layer, the first composite shielding layer being arranged outside the insulated wire group, and a non-hygroscopic lining layer being provided between the first composite shielding layer and the insulated wire group; A second composite shielding layer is arranged on the outside of the first composite shielding layer, a cable core tape layer and a thermal insulation layer are sequentially provided between the first composite shielding layer and the second composite shielding layer, an inner cushion layer and an armor layer are sequentially provided on the outside of the second composite shielding layer, and the outer sheath containing boron nitride ceramic powder is arranged on the outside of the armor layer.

10. Use of the shielded cable according to any one of claims 1 to 9 in rail transit cables.

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