A smart composite cable based on modal isolation and its fabrication method

Abstract

This invention discloses a smart composite cable based on modal isolation and its fabrication method. The cable comprises, from the inside out, a power transmission layer, a control signal layer, an optical fiber communication layer, and a smart protection / external shielding layer. The power transmission layer comprises, from the inside out, a conductor layer, conductor insulation, and a first shielding layer for attenuating low-frequency strong magnetic fields. The control signal layer comprises a total shielding layer and multiple control cores uniformly arranged circumferentially between the total shielding layer and the power transmission layer, with each control core having a sub-shielding layer. The optical fiber communication layer comprises multiple optical fiber groups uniformly arranged circumferentially, with each optical fiber group having a second shielding layer for electro-absorption; the second shielding layer is a non-metallic shielding layer. The smart protection / external shielding layer has a third shielding layer for equipotential shielding. This invention employs a layered composite structure to ensure mechanical performance reliability and uses an asymmetric shielding architecture to achieve full-spectrum interference suppression from extremely low frequencies to high frequencies.

Description

Technical Field

[0001] This invention relates to the field of cable technology, and in particular to a smart composite cable based on modal isolation and its preparation method. Background Technology

[0002] With the rapid development of intelligent manufacturing, the Industrial Internet, and automated production lines, modern industrial equipment places higher demands on the transmission performance, integration, and reliability of cables. Traditional cable systems typically employ a separate wiring scheme, where power cables, control cables, and optical fibers are laid separately. This leads to inherent drawbacks such as large space occupation, severe signal interference, and high maintenance costs. To address these issues, the industry has begun researching composite cable technology that integrates multiple functions. However, existing composite cable technology still suffers from the following serious defects and technical bottlenecks that urgently need to be resolved:

[0003] (1) Insufficient shielding effectiveness and incomplete spectrum coverage:

[0004] Existing technologies mostly employ simple shielding layer stacking (such as aluminum foil + copper wire braiding) or homogeneous shielding designs. This design is only effective against high-frequency electromagnetic interference (EMI), but has extremely weak suppression capability against low-frequency strong magnetic fields (50 / 60Hz and harmonics) generated by power lines.

[0005] (2) Poor dynamic mechanical reliability:

[0006] Existing structures simply combine rigid metallic materials (such as shielding layers), brittle materials (such as optical fibers), and flexible polymers, resulting in a severe mismatch in the mechanical properties (modulus, elasticity) between the layers. In dynamic applications involving high-frequency bending and twisting, internal shear stress is easily generated.

[0007] (3) There is an inherent conflict between grounding and compatibility design:

[0008] All-metal shielding layers are prone to forming complex ground loops. Potential differences between different grounding points can introduce ground loop interference, and this low-frequency noise is fatal to control signals.

[0009] Therefore, most existing smart composite cables are a kind of "piecemeal" integration, failing to truly solve a series of systemic problems such as interference synergy suppression and mechanical performance matching. Summary of the Invention

[0010] The purpose of this invention is to address the shortcomings of existing technologies by proposing a smart composite cable based on modal isolation and its preparation method. It adopts a layered composite structure to ensure mechanical performance reliability and uses an asymmetric shielding architecture to achieve full-spectrum interference suppression from extremely low frequencies to high frequencies. This completely solves the signal distortion problem caused by the coexistence of high and low frequency interference in complex industrial environments, providing the ultimate solution for high-reliability data transmission.

[0011] The technical solution to achieve the objective of this invention is:

[0012] A smart composite cable based on modal isolation includes, from the inside out, a power transmission layer, a control signal layer, an optical fiber communication layer, and a smart protection / external shielding layer. The power transmission layer includes, from the inside out, a conductor layer, conductor insulation, and a first shielding layer for attenuating low-frequency strong magnetic fields. The control signal layer includes a main shielding layer and multiple control cores uniformly arranged circumferentially between the main shielding layer and the power transmission layer; each control core has a sub-shielding layer. The optical fiber communication layer includes multiple optical fiber groups uniformly arranged circumferentially; each optical fiber group has a second shielding layer for electrical absorption, and this second shielding layer is a non-metallic shielding layer. The smart protection / external shielding layer has a third shielding layer for equipotential shielding.

[0013] Furthermore, the conductor layer is formed by pressing together multiple fan-shaped wires, the conductor insulation is a ceramicized silicone rubber insulation layer, and the first shielding layer is made of a high-permeability nanocrystalline alloy strip, and a continuous magnetic path is formed by longitudinal laser seamless welding process.

[0014] Furthermore, the optical fiber assembly also includes an elastic buffer layer, a stainless steel tube, and multiple optical fiber units sequentially nested within the second shielding layer, with water-blocking grease filling the gap between the optical fiber units and the stainless steel tube.

[0015] Furthermore, the second shielding layer is a carbon nanotube gradient-distributed polymer-based composite material layer.

[0016] Furthermore, the intelligent protection and external shielding layer also includes an outer sheath wrapped around the third shielding layer and a conformal intelligent sensing layer and a high-strength aramid yarn braided layer sequentially disposed within the third shielding layer. The braiding density of the high-strength aramid yarn braided layer is ≥95%, and the tensile strength is ≥3000N.

[0017] Furthermore, the conformal intelligent sensing layer includes a sensing optical fiber that is bonded to the outer surface of the high-strength aramid yarn braided layer in a sinusoidal path by coating with flexible adhesive, and the sensing optical fiber is engraved with an FBG grating.

[0018] Furthermore, an isolation layer is provided outside the conformal intelligent sensing layer to smoothly wrap, fix and protect the conformal intelligent sensing layer, so as to isolate it from the third shielding layer and prevent short circuit or wear. The isolation layer is made of flexible TPU or PE material.

[0019] Furthermore, the third shielding layer is a silver-plated nylon filament braided layer, and the braiding angle of the silver-plated nylon filament braided layer is 55~65°.

[0020] Furthermore, the outer sheath is made of thermoplastic polyurethane with added halogen-free environmentally friendly flame retardant, and has a continuous corrugated annular structure in cross-section.

[0021] Furthermore, the height difference between the troughs and crests of the outer sheath is 0.8~1.2mm, and the corrugation pitch is 10~15mm.

[0022] Furthermore, the continuous corrugation of the annular structure forms an axially extending array of grooves on the inner wall of the outer sheath. The cross-section of the grooves is semi-elliptical or trapezoidal, with a depth of 0.2~0.3mm, a width of 0.5~1mm, and a spacing of 3~5mm between adjacent grooves.

[0023] A method for fabricating a smart composite cable based on modal isolation, used to fabricate the smart composite cable as described above, specifically includes the following steps:

[0024] Step S1: Prepare the power transmission layer, control core, and optical fiber assembly separately;

[0025] Step S2: Overall cabling. Using a concentric stranding device, according to the structural design requirements, the prepared power transmission layer, the required number of control cores and optical fiber groups are stranded synchronously and wrapped with water-blocking tape to form the cable core. The tension of each unit is adjusted in real time through an online tension monitoring system to ensure that the stranded structure is tight and round, and the concentricity deviation of each layer is less than ±0.1mm.

[0026] Step S3: Prepare the intelligent protection and external shielding layer;

[0027] The stranded cable core is tightly braided with high-strength aramid yarn on its outside by a high-speed braiding machine, with a braiding density of ≥95%, forming a high-strength aramid yarn braided layer, which serves as a load-bearing layer that bears the main tensile strength.

[0028] The cable core is guided by a programmable eccentric guide wheel to guide the sensing optical fiber with the FBG array written on it to circle the outside of the high-strength aramid yarn braided layer in a precise sine wave path. Low modulus flexible adhesive is simultaneously and uniformly coated on the surface of the sensing optical fiber and the high-strength aramid yarn braided layer. The adhesive is then cured quickly in a UV curing oven, which firmly "attaches" and shapes the sensing optical fiber on the surface of the load-bearing layer.

[0029] The cable core, after the sensing layer has been attached, is braided with silver-plated nylon filaments on the outside by another high-speed braiding machine to form a third shielding layer that has both electromagnetic shielding and physical protection functions. Then, thermoplastic polyurethane material is extruded through an extruder and a halogen-free environmentally friendly flame retardant is incorporated using twin-screw blending technology. The outlet of the extruder is equipped with a corrugated mold that matches the structural design of the cable to form the outermost corrugated outer sheath.

[0030] By adopting the above technical solution, the present invention has the following beneficial effects:

[0031] (1) This invention innovatively adopts an asymmetric shielding architecture that combines a first shielding layer for magnetic shielding, a second shielding layer for electrical absorption, and a third shielding layer for equipotential shielding. This breaks through the limitations of traditional single shielding technology and achieves full-spectrum interference suppression from extremely low frequency to high frequency. It completely solves the signal distortion problem caused by the coexistence of high and low frequency interference in complex industrial environments and provides the ultimate solution for high-reliability data transmission. At the same time, this invention takes the power core as the center and sets the control core around the power core in the circumferential direction. At the same time, the optical fiber group is set around the control core layer to form a multi-layer stranded bundle, which simplifies the cabling process. The overall structure is compact and highly integrated, and the wiring is more reasonable. Compared with the traditional design, it saves more than 60% of space and helps the miniaturization and lightweight design of equipment.

[0032] (2) This invention uses multiple fan-shaped conductors pressed together to form a conductor layer with a circular cross-section. Under the premise of the same conductor cross-sectional area, it takes into account both space utilization and flexibility. It uses a high magnetic permeability nanocrystalline alloy strip with an initial relative magnetic permeability μ i ≥80000, which can effectively attenuate low-frequency strong magnetic field interference.

[0033] (3) The fiber optic assembly of the present invention adopts a stainless steel tube loose tube structure as the core protection and containment structure of the internal fiber optics and is filled with waterproof grease, which can not only block water, but also play a role in buffering and chemical protection. By setting an elastic buffer layer, it can effectively absorb and disperse external vibration and impact energy, and prevent the force from being directly transmitted to the fiber optics. When the cable is bent, the layer deforms, providing space for the internal stainless steel tube to move, avoiding excessive strain on the fiber optics, thereby solving the mechanical mismatch problem.

[0034] (4) The present invention uses carbon nanotube gradient design to achieve the transition from high internal reflection to high external absorption, effectively suppressing high frequency electromagnetic interference. As a non-metallic shielding layer, it fundamentally eliminates the grounding loop interference problem caused by the metal shielding layer. At the same time, as the outermost sheath of the optical fiber group, it provides preliminary physical and environmental protection for the internal elastic buffer layer and optical fiber unit.

[0035] (5) The present invention uses a high-strength aramid yarn braided layer to bear most of the axial tension generated during cable operation and installation, ensuring that the internal precision functional cores (such as optical fiber groups and control cores) are in a "zero tension" or low tension state and are protected from stress damage. At the same time, its flexible braided structure provides radial buffer for the internal cores, resisting external impact and compression, forming a tensile buffer layer. In addition, by setting the conformal intelligent sensing layer between the high-strength aramid yarn braided layer and the third shielding layer, on the one hand, the sensing signal is fully protected from external electromagnetic interference, and on the other hand, it can directly sense the strain of the high-strength aramid yarn braided layer, thereby more accurately monitoring the overall tensile and bending stress of the cable.

[0036] (6) The sensing fiber of the present invention is engraved with FBG grating, which can sense the temperature distribution on the surface of the cable in real time, realize overheating early warning, and the temperature measurement accuracy is ±0.5℃. Combined with OTDR technology, it can locate and identify vibration, impact and other events along the cable length. At the same time, the "sine wave" layout method is adopted, which makes it extremely sensitive to axial tension and bending strain. It can accurately monitor the overload tension, bending radius and vibration state of the cable, and the measurement accuracy can reach ±5με.

[0037] (7) The third shielding layer of the present invention uses a silver-plated nylon filament braid as the third shielding layer. The tough nylon substrate provides excellent resistance to cutting, tearing and abrasion, serving as a solid barrier against external mechanical damage. A specific braiding angle is used to optimize flexibility. While providing the last shield against low-frequency radiation interference and electrostatic discharge (ESD) from the external environment, its high resistance characteristics effectively suppress the formation of ground loop current.

[0038] (8) The outer sheath of the present invention adopts a continuous corrugated ring structure, which greatly improves the longitudinal flexibility and radial compressive strength of the cable.

[0039] (9) This invention uses a groove array as a micro-channel. This channel, together with the mesh gaps of the outer silver-plated nylon braided layer, forms a distributed capillary drainage channel network. Once the outer sheath is partially damaged and water enters, the liquid will first be confined within this capillary network and flow axially, rather than immediately penetrating laterally and eroding the inner core layer. This design realizes physical water-sensitive sensing. When water flows along the channel to the cable end, it can be visually detected or detected by installing a humidity sensor at the termination, thereby issuing a timely water ingress warning and providing valuable response time for maintenance personnel. At the same time, the channel structure on the inner wall increases the elastic deformation space inside the outer sheath to a certain extent, further improving the overall flexibility of the cable, and increasing the heat dissipation area on the inner surface of the outer sheath, thus improving the heat dissipation performance of the cable.

[0040] (10) The preparation method of the present invention adopts a modular layered manufacturing strategy. First, the power transmission layer, control signal layer and optical fiber communication layer are made separately, and then the overall integration is carried out to finally complete the construction of the external intelligent protection and external shielding layer, which greatly reduces the manufacturing difficulty and risk and ensures the high consistency and reliability of the product. Attached Figure Description

[0041] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0042] Figure 1 This is a schematic diagram of the structure of the present invention;

[0043] Figure 2 This is a schematic diagram of the optical fiber assembly of the present invention.

[0044] The labels in the attached diagram are:

[0045] Power transmission layer 1, conductor layer 1-1, conductor insulation 1-2, first shielding layer 1-3;

[0046] Control signal layer 2, main shielding layer 2-1, sub-shielding layer 2-2, control conductor 2-3, control insulation 2-4;

[0047] Fiber optic communication layer 3, second shielding layer 3-1, elastic buffer layer 3-2, stainless steel tube 3-3, multiple fiber optic units 3-4, water-blocking grease 3-5;

[0048] Intelligent protection and external shielding layer 4, high-strength aramid yarn woven layer 4-1, conformal intelligent sensing layer 4-2, isolation layer 4-3, third shielding layer 4-4, outer sheath 4-5, flow guide groove 4-6;

[0049] Water-blocking strip 5. Detailed Implementation

[0050] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0051] Example 1, such as Figure 1 The intelligent composite cable based on modal isolation shown includes a power transmission layer 1, a control signal layer 2, an optical fiber communication layer 3, and an intelligent protection and external shielding layer 4 arranged sequentially from the inside out. The overall structural design adopts a layered composite structure to ensure the reliability of mechanical performance, and adopts an asymmetric shielding architecture to achieve full-spectrum interference suppression from extremely low frequency to high frequency. It completely solves the signal distortion problem caused by the coexistence of high and low frequency interference in complex industrial environments, and provides the ultimate solution for high-reliability data transmission.

[0052] Specifically, the power transmission layer 1 includes, from the inside out, a conductor layer 1-1, conductor insulation 1-2, and a first shielding layer 1-3 for attenuating low-frequency strong magnetic fields. The conductor layer 1-1 is formed by tightly pressing multiple high-purity oxygen-free copper wires with fan-shaped cross-sections, improving space utilization and flexibility. The conductor insulation 1-2 is a ceramicized silicone rubber insulation layer with a high temperature resistance rating of ≥180℃. The first shielding layer 1-3 uses a high-permeability nanocrystalline alloy strip, such as Fe... 73.5 Si 13.5 B9Nb3Cu1, and formed a continuous magnetic path through longitudinal laser seamless welding process, with an initial relative permeability μi≥80000 (test conditions: frequency 1kHz, AC magnetic field strength ≤0.1A / m), is specifically designed for efficient attenuation of low-frequency strong magnetic field interference.

[0053] The control signal layer 2 includes a main shielding layer 2-1 and multiple control wire cores evenly distributed circumferentially between the main shielding layer 2-1 and the power transmission layer 1. Each control wire core adopts a wire pair structure, including a sub-shielding layer 2-2 and a pair of control conductors 2-3 disposed within the sub-shielding layer 2-2. The control conductors 2-3 are made of multi-strand silver-plated copper wire with a specification of 18~24AWG and a stranding pitch ≤10 times the wire diameter to reduce the skin effect. Each control conductor 2-3 is covered with foamed polyethylene extrusion to form control insulation 2-4, and the dielectric constant of the control insulation 2-4 is ≤1.5 to reduce signal delay. The sub-shielding layer 2-2 is an aluminum-plastic composite film, and the main shielding layer 2-1 is a tin-plated copper wire braided main shielding layer with a coverage of ≥90% for dissipating high-frequency interference current.

[0054] The fiber optic communication layer 3 comprises multiple fiber optic groups evenly arranged circumferentially. The structural design of these fiber optic groups follows a logical sequence of "core transmission → mechanical protection → electromagnetic protection," such as... Figure 2As shown, the structure includes, from the outside in, a second shielding layer 3-1, an elastic buffer layer 3-2, a stainless steel tube 3-3, and multiple optical fiber units 3-4. Water-blocking grease 3-5 is filled between the optical fiber units 3-4 and the stainless steel tube 3-3 for water blocking, buffering, and chemical protection. The optical fiber units 3-4 use G.657.A2 bend-resistant single-mode optical fiber and are placed side-by-side inside the stainless steel tube 3-3. The corrugated wall of the stainless steel tube 3-3 facilitates the close fit of the outer elastic buffer layer 3-2, preventing mutual rotation and forming a loose-tube core transmission unit that provides a stable and reliable optical signal transmission channel. The stainless steel tube 3-3 provides strong resistance to pressure and lateral impact. The elastic buffer layer 3-2 is a layer of silicone gel elastomer covering the stainless steel tube 3-3. Its soft elastic modulus forms a soft transition zone between the rigid stainless steel tube 3-3 and the outer shielding layer, effectively absorbing and dispersing external vibration and impact energy, preventing direct force transmission to the optical fiber units 3-4. When the cable bends, this layer deforms, providing space for the internal stainless steel tube 3-3 to move, preventing excessive strain on the fiber optic unit 3-4 and effectively solving the "mechanical mismatch" problem. The second shielding layer 3-1 is used for electrical absorption and is a layer of polymer-based composite material with a gradient distribution of carbon nanotubes. Its gradient design achieves a transition from high reflection inside to high absorption outside, effectively suppressing high-frequency electromagnetic interference. As a non-metallic shielding layer, it fundamentally eliminates the grounding loop interference problem caused by metallic shielding layers. At the same time, as the outermost sheath of this functional unit, it provides preliminary physical and environmental protection for the internal elastic buffer layer 3-2 and fiber optic unit 3-4.

[0055] The intelligent protection and external shielding layer 4 consists of a high-strength aramid yarn woven layer 4-1, a conformal intelligent sensing layer 4-2, an isolation layer 4-3, a third shielding layer 4-4, and an outer sheath 4-5, from the inside out, achieving a deep integration of mechanical strength, intelligent sensing, and multiple protections.

[0056] The high-strength aramid yarn braided layer 4-1 is made of aramid yarn produced by Kevlar® or Technora®, with a braiding density of ≥95% and a tensile strength of ≥3000N. As a load-bearing layer, it bears most of the axial tension generated during cable operation and installation, ensuring that the internal precision functional cores, such as optical fibers and control pairs, are in a "zero tension" or low tension state and are protected from stress damage. At the same time, its flexible braided structure provides radial buffer for the internal cores, resisting external impacts and compression.

[0057] The conformal intelligent sensing layer 4-2 includes a sensing optical fiber bonded to the outer surface of the high-strength aramid yarn braided layer in a sinusoidal path using flexible adhesive. This sensing optical fiber is engraved with an FBG grating to sense the cable surface temperature distribution in real time, enabling overheat warning with a temperature measurement accuracy of ±0.5℃. Combined with OTDR technology, it can locate and identify vibration, impact, and other events along the cable length. The sinusoidal layout makes it extremely sensitive to axial tension and bending strain, accurately monitoring the cable's overload tension, bending radius, and vibration state with a measurement accuracy of ±5με. This layer is positioned within the third shielding layer 4-4, thus the sensing signal is fully protected from external electromagnetic interference, allowing for direct sensing of the strain in the aramid load-bearing layer and more accurate monitoring of the cable's overall tensile and bending stress.

[0058] The isolation layer 4-3 is made of flexible TPU or PE material, which smoothly wraps, fixes and protects the conformal intelligent sensing layer 4-2, so as to isolate it from the third shielding layer 4-4 and prevent short circuits or wear.

[0059] The third shielding layer 4-4 is a silver-plated nylon filament braided layer with a braiding angle of 55~65°. Its tough nylon substrate provides excellent resistance to cutting, tearing and abrasion, serving as a solid barrier against external mechanical damage. The specific braiding angle optimizes flexibility. While providing the last layer of shielding against low-frequency radiation interference and electrostatic discharge (ESD) from the external environment, its high resistance characteristics effectively suppress the formation of ground loop current.

[0060] The outer sheath 4-5 is made of thermoplastic polyurethane with added halogen-free environmentally friendly flame retardants. It has a continuous corrugated annular structure with a height difference of 0.8~1.2mm between the troughs and crests, and a corrugation pitch of 10~15mm. This significantly improves the cable's longitudinal flexibility and radial compressive strength, achieving a minimum bending radius ≤5D. The continuous corrugation of the annular structure forms an axially extending array of grooves on the inner wall of the outer sheath 4-5. Each groove has a semi-elliptical or trapezoidal cross-section, a depth of 0.2~0.3mm, a width of 0.5~1mm, and a spacing of 3~5mm between adjacent grooves. This creatively forms micro-channels 4-6 on the inner surface of the outer sheath 4-5. The drainage channel, together with the mesh gaps of the outer silver-plated nylon braided layer, forms a distributed capillary drainage channel network. In the event of localized damage to the outer sheath and water ingress, the liquid will first be confined within this capillary network and flow axially, rather than immediately penetrating laterally and eroding the inner core layer. This design achieves physical water-sensitive sensing. When water flows along the drainage channel to the cable end, it can be visually detected or detected by installing a humidity sensor at the termination, thus issuing a timely water ingress warning and providing valuable response time for maintenance personnel. Simultaneously, the drainage channel structure on the inner wall increases the elastic deformation space inside the outer sheath to a certain extent, further improving the overall flexibility of the cable and increasing the heat dissipation area on the inner surface of the outer sheath, thus improving the cable's heat dissipation performance.

[0061] The innovative cable structure design of this embodiment adopts an asymmetric shielding architecture of "nanocrystalline alloy (magnetic shielding), CNT gradient material (electric absorption), and silver-plated nylon (equipotential shielding)," breaking through the limitations of traditional single shielding technology. It achieves deep integration of four major functions—power transmission, control signals, optical fiber communication, and intelligent monitoring—within a single cable structure. It saves more than 60% of wiring space, which helps to miniaturize and lighten the design of equipment. It also achieves full-spectrum interference suppression from extremely low frequencies (50Hz power frequency magnetic field, shielding effectiveness > 35dB) to high frequencies (1MHz-10GHz, shielding effectiveness > 65dB).

[0062] The biomimetic buffer structure of "stainless steel tube, silicone gel elastomer, and aramid load-bearing layer" perfectly solves the problem of mechanical performance mismatch of heterogeneous materials. Under the harsh condition of diameter bending ratio ≤ 5D, the reciprocating bending life exceeds 1 million cycles, which is more than 10 times higher than the traditional structure. It meets the long-term reliability requirements of high-frequency bending scenarios such as industrial robots and mobile equipment, and significantly reduces maintenance costs.

[0063] Employing an innovative "coating and bonding with isolation layer fixing" process, the FBG sensor network is precisely embedded in a sinusoidal wave path. The sensing system is doubly protected by the isolation layer and shielding layer, completely isolating it from external electromagnetic interference, resulting in an extremely high signal-to-noise ratio. It enables in-situ monitoring of multiple parameters such as temperature (±0.5℃), strain (±5με), and vibration, reducing fault response time by more than 60% compared to external mounting methods. This transforms the cable from a passive transmission component into an intelligent sensing terminal, providing a precise data foundation for predictive maintenance.

[0064] The silver-plated nylon braided layer is placed under the outer sheath 4-5, forming an effective "Faraday cage". Any static charge accumulated on the surface of the outer sheath 4-5 can be quickly conducted away, achieving true anti-static (ESD) protection and providing excellent physical protection capabilities such as cut resistance and abrasion resistance.

[0065] The outer sheath 4-5 uses flame-retardant reinforced thermoplastic polyurethane (FR-TPU) as its base material, achieving the highest UL94 V-0 flame retardant rating through halogen-free environmentally friendly flame retardants. It is safe and reliable, possessing excellent oil resistance, UV resistance, and high abrasion resistance, making it suitable for complex and harsh working environments. The continuous corrugated structure on the outer surface gives it a very small bending radius (≤5D), facilitating installation in confined spaces. The micro-channels on the inner surface, together with the braided layer, form a distributed network that confines intruding moisture within the channels and guides it axially, effectively preventing lateral water penetration and corrosion of the internal core. This achieves physical water-sensitive sensing functionality, significantly increasing the heat dissipation area of ​​the outer sheath's inner wall, improving the cable's internal heat conduction and dissipation paths, helping to reduce operating temperature, and enhancing safety and lifespan. The synergistic design of the outer corrugations and inner channels of the outer sheath 4-5 enhances the cable's overall flexibility, maintaining its flexibility and ease of use while providing high strength and protection.

[0066] When the outer sheath is damaged and water enters, the water can be guided to both ends of the cable through the drainage channel. On the other hand, if the water penetrates into the core area of ​​the cable, the extruded isolation layer, the water-blocking tape at the concentric cabling of the three core components, and the water-blocking paste in the optical fiber layer can all play a timely role in blocking water radially and longitudinally, thus achieving excellent waterproof function.

[0067] Example 2: This example provides a method for preparing the mode-isolated smart composite cable of Example 1, specifically including the following steps:

[0068] Step S1: Prepare the power transmission layer, control core, and optical fiber assembly separately;

[0069] Step S11: Fabrication of the power transmission layer:

[0070] Conductor stranding: Multiple strands of high-purity oxygen-free copper wire are tightly stranded in a fan shape using a tubular stranding machine to obtain a conductor with high filler density and excellent flexibility.

[0071] Insulation extrusion: The stranded conductor is extruded through an extruder to form a ceramicized silicone rubber insulation layer, and then cross-linked and cured through a high-temperature vulcanization channel to form a high-temperature resistant (≥180℃) insulated wire core.

[0072] The first shielding layer 1-3 is formed by using a longitudinal wrapping process to tightly wrap a high-permeability nanocrystalline alloy strip around the insulated wire core. Immediately afterward, a longitudinal laser welding device is used to perform high-speed, seamless welding of the longitudinal seams of the alloy strip, forming a continuous, complete, and sealed metal tubular magnetic shielding layer, completely eliminating magnetic leakage.

[0073] Step S12: Controlled core preparation:

[0074] Unit Pair Fabrication: Multiple strands of silver-plated copper wire are twisted together using a twisting machine at a pitch ≤ 10 times the wire diameter to form differential pairs. Foamed polyethylene insulation is extruded onto the twisted pairs to form unit wires with low dielectric constant (εr ≤ 1.5). An aluminum-plastic composite film is longitudinally wrapped around each unit wire to form a secondary shielding layer 2-2.

[0075] Cabling and overall shielding: Multiple individually shielded unit wire pairs are twisted into a cable using a cage stranding machine. Filler ropes can be added during cabling as needed. After cabling, a tinned copper wire braided layer (coverage ≥90%) is woven around the bundled cable as the overall shielding layer 2-1 to discharge high-frequency interference.

[0076] Step S13: Fabrication of the optical fiber assembly:

[0077] Multiple G.657.A2 bend-resistant single-mode optical fibers are placed in a stainless steel tube and injected with waterproof grease to form the core transmission unit. A layer of silicone gel elastomer is extruded over the stainless steel tube to form an elastic buffer layer. Subsequently, a layer of carbon nanotube (CNT) gradient-distributed polymer-based composite material is extruded over the tube using a second extruder to form a non-metallic electro-absorption shielding layer, namely the second shielding layer 3-1.

[0078] Step S2: Overall cabling. Using a concentric stranding device, according to the structural design requirements, the prepared power transmission layer, the required number of control cores and optical fiber groups are stranded synchronously and wrapped with water-blocking tape 5 to form the cable core. The tension of each unit is adjusted in real time through an online tension monitoring system to ensure that the stranded structure is tight and round, and the concentricity deviation of each layer is less than ±0.1mm.

[0079] Step S3: Prepare the intelligent protection and external shielding layer;

[0080] The stranded cable core is tightly braided with high-strength aramid yarn on its outside by a high-speed braiding machine, with a braiding density of ≥95%, forming a high-strength aramid yarn braided layer, which serves as a load-bearing layer that bears the main tensile strength.

[0081] The cable core is guided by a programmable eccentric guide wheel to guide the sensing optical fiber with the FBG array written on it to circle the outside of the high-strength aramid yarn braided layer in a precise sine wave path. Low modulus flexible adhesive is simultaneously and uniformly coated on the surface of the sensing optical fiber and the high-strength aramid yarn braided layer. The adhesive is then cured quickly in a UV curing oven, which firmly "attaches" and shapes the sensing optical fiber on the surface of the load-bearing layer.

[0082] The cable core, after the sensing layer has been attached, is braided with silver-plated nylon filaments on the outside by another high-speed braiding machine to form a third shielding layer that has both electromagnetic shielding and physical protection functions. Then, thermoplastic polyurethane material is extruded through an extruder and a halogen-free environmentally friendly flame retardant is incorporated using twin-screw blending technology. The outlet of the extruder is equipped with a corrugated mold that matches the structural design of the cable to form the outermost corrugated outer sheath.

[0083] The manufacturing method in this embodiment adopts a modular layered manufacturing strategy. First, the power transmission layer, control signal layer, and optical fiber communication layer are fabricated separately, and then they are integrated as a whole to finally complete the construction of the external intelligent protection and external shielding layer. This greatly reduces the manufacturing difficulty and risk and ensures the high consistency and reliability of the product.

[0084] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A smart composite cable based on modal isolation, characterized in that: The system comprises, from the inside out, a power transmission layer, a control signal layer, an optical fiber communication layer, and an intelligent protection / external shielding layer. The power transmission layer includes, from the inside out, a conductor layer, conductor insulation, and a first shielding layer for attenuating low-frequency strong magnetic fields. The control signal layer includes a main shielding layer and multiple control cores evenly distributed circumferentially between the main shielding layer and the power transmission layer; each control core has a sub-shielding layer. The optical fiber communication layer includes multiple optical fiber groups evenly distributed circumferentially; each optical fiber group has a second shielding layer for electro-absorption, and this second shielding layer is a non-metallic shielding layer. The intelligent protection / external shielding layer has a third shielding layer for equipotential shielding.

2. The intelligent composite cable based on modal isolation according to claim 1, characterized in that: The conductor layer is formed by pressing together multiple fan-shaped wires. The conductor insulation is a ceramicized silicone rubber insulation layer. The first shielding layer is made of a high-permeability nanocrystalline alloy strip and a continuous magnetic path is formed by longitudinal laser seamless welding process.

3. The intelligent composite cable based on modal isolation according to claim 1, characterized in that: The optical fiber assembly also includes an elastic buffer layer, a stainless steel tube, and multiple optical fiber units sequentially nested within the second shielding layer. The gap between the optical fiber units and the stainless steel tube is filled with water-blocking grease.

4. The intelligent composite cable based on modal isolation according to claim 1, characterized in that: The second shielding layer is a polymer-based composite material layer with a gradient distribution of carbon nanotubes.

5. The intelligent composite cable based on modal isolation according to claim 1, characterized in that: The intelligent protection and external shielding layer also includes an outer sheath wrapped around the third shielding layer and a conformal intelligent sensing layer and a high-strength aramid yarn braided layer arranged sequentially within the third shielding layer. The braiding density of the high-strength aramid yarn braided layer is ≥95%, and the tensile strength is ≥3000N.

6. The intelligent composite cable based on modal isolation according to claim 5, characterized in that: The conformal intelligent sensing layer includes a sensing optical fiber that is coated with flexible adhesive and attached to the outer surface of a high-strength aramid yarn braided layer in a sinusoidal path, and the sensing optical fiber is engraved with an FBG grating.

7. The intelligent composite cable based on modal isolation according to claim 5, characterized in that: The third shielding layer is a silver-plated nylon filament braided layer, and the braiding angle of the silver-plated nylon filament braided layer is 55~65°.

8. The intelligent composite cable based on modal isolation according to claim 7, characterized in that: The outer sheath is made of thermoplastic polyurethane with added halogen-free environmentally friendly flame retardant, and has a continuous corrugated annular structure in cross section.

9. A smart composite cable based on modal isolation according to claim 8, characterized in that: The continuous corrugations of the annular structure form an array of grooves extending axially on the inner wall of the outer sheath. The cross-section of the grooves is semi-elliptical or trapezoidal, with a depth of 0.2~0.3mm, a width of 0.5~1mm, and a spacing of 3~5mm between adjacent grooves.

10. A method for preparing a smart composite cable based on modal isolation, used to prepare the smart composite cable as described in any one of claims 1 to 9, characterized in that, Includes the following steps: Step S1: Prepare the power transmission layer, control core, and optical fiber assembly separately; Step S2: Overall cabling. Using a concentric stranding device, according to the structural design requirements, the prepared power transmission layer, the required number of control cores and optical fiber groups are stranded synchronously and wrapped with water-blocking tape to form the cable core. The tension of each unit is adjusted in real time through the online tension monitoring system to ensure that the stranded structure is tight and round, and the concentricity deviation of each layer is less than ±0.1mm. Step S3: Prepare the intelligent protection and external shielding layer; The stranded cable core is tightly braided with high-strength aramid yarn on its outside by a high-speed braiding machine, with a braiding density of ≥95%, forming a high-strength aramid yarn braided layer, which serves as a load-bearing layer to bear the tensile strength. The cable core is guided by a programmable eccentric guide wheel to guide the sensing optical fiber with the FBG array written on it to circle the outside of the high-strength aramid yarn braided layer in a precise sine wave path. Low modulus flexible adhesive is simultaneously and uniformly coated on the surface of the sensing optical fiber and the high-strength aramid yarn braided layer. The adhesive is then cured quickly in a UV curing oven, which firmly "attaches" and shapes the sensing optical fiber on the surface of the load-bearing layer. The cable core, after the sensing layer has been attached, is braided with silver-plated nylon filaments on the outside by another high-speed braiding machine to form a third shielding layer that has both electromagnetic shielding and physical protection functions. Then, thermoplastic polyurethane material is extruded through an extruder and a halogen-free environmentally friendly flame retardant is incorporated using twin-screw blending technology. The outlet of the extruder is equipped with a corrugated mold that matches the structural design of the cable to form the outermost corrugated outer sheath.

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