Flexible cable and method for manufacturing the same

Abstract

The application relates to the cable technical field, in particular to a flexible cable and a preparation method thereof. The flexible cable is characterized in that a monitoring layer is arranged outside a shielding layer, electromagnetic crosstalk of an optical fiber grating sensor and a temperature sensor in the monitoring layer is effectively isolated by the shielding layer; meanwhile, the monitoring layer is coated with a filling layer prepared by mixing metal oxide, inorganic hydroxide and silicate additives according to a mass ratio of (4-6):(2-4):(1.5-2.5). The specific filling layer has a very high compression resilience, so that the filling layer can absorb deformation stress when the flexible cable is pressed or bent, thereby protecting the optical fiber grating sensor in the monitoring layer from being broken by rigid extrusion. In addition, the filling layer has a low thermal conductivity, thereby forming a heat insulation effect, preventing heat inside the cable core from dissipating outward, and enabling the temperature sensor outside the shielding layer to accurately capture hotspot data inside the cable core, so that the accuracy of temperature detection is ensured.

Description

Technical Field

[0001] This application relates to the field of cable technology, and more specifically, to a flexible cable and a method for its preparation. Background Technology

[0002] To meet the demands of smart grids and the ubiquitous power Internet of Things, the industry has gradually begun to develop cables with monitoring functions. However, existing cables with this function have the following problems in terms of multi-functional integration: on the one hand, after introducing sensing and monitoring elements inside the cable, the overall structural stability and flexibility of the cable are often compromised, making it difficult to adapt to complex laying environments; on the other hand, strong electromagnetic fields, drastic temperature differences, and external mechanical stress under complex working conditions can easily cause interference or physical damage to the sensing elements inside the cable, leading to distorted monitoring data or even sensor element failure. Summary of the Invention

[0003] The purpose of this invention is to provide a flexible cable that simultaneously achieves accurate condition monitoring and good structural reliability.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a flexible cable, comprising: At least one core unit, each core unit comprising, from the inside out, a conductor core, a fire-resistant layer, an insulation layer, a shielding layer and a monitoring layer, wherein the monitoring layer comprises a fiber optic grating sensor, a temperature sensor and a signal transmission module for transmitting the data obtained by the fiber optic grating sensor and the temperature sensor to an external terminal; A filler layer, which encapsulates at least one wire core unit; the filler layer is made by mixing metal oxide, inorganic hydroxide and silicate additive in a mass ratio of (4-6):(2-4):(1.5-2.5); A flame-retardant layer and a sheath layer are sequentially wrapped around the filler layer.

[0005] Furthermore, the conductor core is formed by twisting multiple copper-magnesium alloy wires and oxygen-free copper wires together, with the mass ratio of the copper-magnesium alloy wires to the oxygen-free copper wires being 1:1 to 7.

[0006] Furthermore, the stranding pitch of the conductor core is 10-12 times the diameter of the conductor core.

[0007] Furthermore, the conductor core is stranded in a regular stranding manner, with adjacent layers stranded in opposite directions.

[0008] Furthermore, the core unit is composed of multiple strands, and the multiple strands of the core unit are twisted together to form a cable core. The filling layer fills the gaps in the cable core and covers the outside of the cable core.

[0009] Furthermore, the fiber Bragg grating sensors are arranged in a distributed manner, with a spacing of 1-2m between two adjacent fiber Bragg grating sensors.

[0010] Furthermore, a semi-conductive shielding layer is provided between the insulating layer and the shielding layer, and the thickness of the semi-conductive shielding layer is 0.1-0.15 mm.

[0011] Furthermore, the shielding layer adopts a double-layer shielding structure, wherein the inner layer is a metal foil shielding layer with a thickness of 0.06 to 0.15 mm, and the outer layer is a metal wire braided shielding layer with a braiding density of not less than 90%, wherein the metal wire is at least one of tin-plated copper wire, bare copper wire, and copper alloy wire.

[0012] Furthermore, the fire-resistant layer is a mica tape wrapping layer with a wrapping overlap rate of ≥50% and a thickness of 0.15-0.25mm; the insulation layer is a cross-linked polyethylene extrusion layer with a thickness of 0.8-1.2mm; the flame-retardant layer is a glass flame-retardant wrapping layer with a wrapping overlap rate of ≥40% and a thickness of 0.2-0.3mm; and the sheath layer is a low-smoke halogen-free polyolefin extrusion layer with a thickness of 1.0-1.5mm.

[0013] This application also provides a method for preparing the above-mentioned flexible cable, comprising: S10: Prepare a conductor core and cover it with a fire-resistant layer, an insulating layer, a shielding layer and a monitoring layer in sequence to obtain a wire core unit; S20: One or more strands of wire core unit are stranded together and a filler layer is extruded on the outside of them. The filler layer is made by mixing metal oxide, inorganic hydroxide and silicate additive in a mass ratio of (4-6):(2-4):(1.5-2.5). S30: A flame-retardant layer and a sheath layer are sequentially wrapped around the outside of the filler layer.

[0014] The beneficial effects of this invention are as follows: The flexible cable of this application places the monitoring layer outside the shielding layer, effectively isolating the internal conductor core from electromagnetic crosstalk to the fiber Bragg grating sensor and temperature sensor within the monitoring layer. Simultaneously, a filling layer made of metal oxides, inorganic hydroxides, and silicate additives in a mass ratio of (4-6):(2-4):(1.5-2.5) covers the monitoring layer. Because this specific filling layer has an extremely high compression resilience (high-elasticity buffer), it can absorb deformation stress when the flexible cable is compressed or bent, protecting the fiber Bragg grating sensor within the monitoring layer from rigid compression and breakage. Furthermore, the low thermal conductivity of this filling layer provides thermal insulation, preventing heat loss from the cable core and allowing the temperature sensor located outside the shielding layer to accurately capture hotspot data within the cable core, thus ensuring accurate temperature detection. Therefore, this flexible cable simultaneously achieves accurate condition monitoring and good structural reliability.

[0015] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a flexible cable according to an embodiment of this application; Figure 2 This is a schematic diagram of a method for preparing a flexible cable according to an embodiment of this application.

[0017] Reference numerals: 1. Core unit; 11. Conductor core; 12. Fire-resistant layer; 13. Insulation layer; 14. Semi-conductive shielding layer; 15. Shielding layer; 16. Monitoring layer; 2. Filling layer; 3. Flame-retardant layer; 4. Sheath layer. Detailed Implementation

[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0020] Please see Figure 1The flexible cable shown in one embodiment of this application comprises, from the inside out, a cable core, a filling layer 2, a flame-retardant layer 3, and a sheath layer 4. The cable core includes at least one conductor unit 1, and each conductor unit 1 includes, from the inside out, a conductor core 11, a fire-resistant layer 12, an insulation layer 13, a shielding layer 15, and a monitoring layer 16. The filling layer 2 encapsulates at least one conductor unit 1; the filling layer 2 is made by mixing metal oxides, inorganic hydroxides, and silicate additives in a mass ratio of (4-6):(2-4):(1.5-2.5).

[0021] The monitoring layer 16 includes a fiber Bragg grating sensor, a temperature sensor, and a signal transmission module. The fiber Bragg grating sensor acquires stress and vibration data of the flexible cable. In one embodiment, the fiber Bragg grating sensor is arranged in a distributed manner, with a spacing of 1-2 meters between adjacent sensors. The temperature sensor acquires the operating temperature data of the flexible cable. In one embodiment, the temperature sensor and the fiber Bragg grating sensor can be arranged synchronously in a distributed manner, with a spacing of 1-2 meters between them. In a preferred example, the temperature sensor and the fiber Bragg grating sensor can be integrated into the same miniature sensing module. The signal transmission module transmits the data acquired by the fiber Bragg grating sensor and the temperature sensor to an external terminal (such as an operation and maintenance terminal) for analysis. This allows for online monitoring and fault warning of the flexible cable's operating status. In one example, the signal transmission module is a discontinuous rigid strip, which can be miniaturized and packaged using a flexible printed circuit board (FPC) substrate to form transmission micronodes. These transmission micronodes are distributed along the longitudinal direction of the flexible cable at relatively large intervals (e.g., 100m-500m) and attached to the outer surface of the shielding layer 15, and are physically connected to the fiber Bragg grating sensor and temperature sensor via micro-wires / fiber optic pigtails. In another example, the signal transmission module can be centrally located at the terminal joints at both ends of the cable, or in an intermediate junction box along the laying route. The signal transmission module is connected to the fiber Bragg grating sensor and temperature sensor via fiber optic pigtails or micro-signal wires, which extend longitudinally along the gap between the outer side of the shielding layer 15 and the inner side of the filling layer 2. In practical applications, the signal transmission module can use wireless transmission to transmit the above data to an external terminal. For example, the signal transmission module can support 5G signal transmission with a transmission delay of ≤10ms to ensure real-time and accurate transmission of monitoring data.

[0022] By placing the monitoring layer 16 outside the shielding layer 15, the shielding layer 15 effectively isolates the electromagnetic crosstalk of the internal conductor core 11 to the fiber optic grating sensor and temperature sensor within the monitoring layer 16. Simultaneously, a filling layer 2, prepared by mixing metal oxides, inorganic hydroxides, and silicate additives in a specific mass ratio of (4-6):(2-4):(1.5-2.5), covers the monitoring layer 16. In some specific embodiments, the metal oxide is selected from one or more combinations of alumina, magnesium oxide, zinc oxide, and titanium dioxide; the inorganic hydroxide is selected from one or more combinations of magnesium hydroxide, aluminum hydroxide, layered bimetallic hydroxide (hydrotalcite), and zinc hydroxystannate; and the silicate additive is selected from sodium silicate, potassium silicate, and aluminum silicate. Specific mass ratios are, for example, 4:2:1.5, 4.5:3.5:1.8, 5:3:2, and 6:4:2.5.

[0023] Because this specific filler layer 2 has an extremely high compression resilience (high elasticity buffer), it can absorb deformation stress when the flexible cable is compressed or bent, thus protecting the fiber Bragg grating sensor inside the monitoring layer 16 from rigid compression and breakage. Furthermore, the low thermal conductivity of the filler layer 2 provides thermal insulation, preventing heat loss from the cable core. This allows the temperature sensor located outside the shielding layer 15 to accurately capture hotspot data inside the cable core, ensuring accurate temperature detection. Therefore, this flexible cable simultaneously achieves accurate condition monitoring and good structural reliability.

[0024] It should be noted that in existing cable development, the monitoring layer 16 is typically positioned close to the conductor core. This is because conventional technology suggests that, to accurately reflect the conductor core's heating status, the temperature sensor should be integrated as close to the core as possible. Furthermore, since fiber Bragg grating sensors are relatively fragile, and the existing flame-retardant layers formed by single inorganic flame-retardant fillers (such as simple magnesium hydroxide or alumina) are hard and have low compression resilience, the fiber Bragg grating sensor needs to be positioned away from the flame-retardant layer. However, this existing arrangement of the monitoring layer presents the following problems: 1. The closer to the internal high-current area, the more severe the electromagnetic crosstalk to the temperature sensor, resulting in extremely high signal distortion; 2. Placing the fiber Bragg grating sensor inside the cable means that when the cable is laid in complex environments, bending or being compressed, the conventional filler layer cannot provide effective flexible buffering, easily leading to the fiber being rigidly squeezed and broken. To solve this problem, existing technologies have attempted to move the fiber Bragg grating sensor and temperature sensor to the surface of the sheath layer. While this method reduces interference, it is highly susceptible to external ambient temperature, causing a sharp increase in temperature measurement error and failing to accurately capture the core hotspot data inside the insulation layer. In addition, existing technologies have attempted to add rigid armor protection, but this would prevent fiber optic grating sensors from sensitively detecting the cable's minute stress and vibration deformation.

[0025] To address the problems of existing technologies, this embodiment places the monitoring layer 16 (including a fiber optic grating sensor and a temperature sensor) on the outside of the shielding layer 15 and the inside of the filling layer 2. The shielding layer 15 can effectively shield the strong electromagnetic interference from the conductor core 11, enhancing the anti-interference capability (crosstalk value ≤ -65dB) of the area where the temperature sensor is located. Simultaneously, this embodiment abandons the conventional single filler and specifically uses a mineral filler material prepared by mixing metal oxides, inorganic hydroxides, and silicate additives in a mass ratio of (4-6):(2-4):(1.5-2.5), which tightly covers the periphery of the monitoring layer 16. The specific ratio of filler layer 2 not only provides excellent flame retardant properties but also produces unexpected synergistic physical effects: On the one hand, its extremely low thermal conductivity (0.082 W / (m·K)) achieves thermal insulation, preventing heat loss from the inside of the flexible cable to the outside. This allows the outer side of the shielding layer 15 to accurately and stably reflect the core heat conducted from the insulation layer 13, solving the problem of inaccurate temperature measurement caused by the external displacement of the temperature sensor, reducing the temperature measurement error to only ±0.5℃. On the other hand, the filler material with the (4~6):(2~4):(1.5~2.5) ratio has a compression resilience of up to ≥92%. This flexibility provides a highly elastic flexible armor for the fiber Bragg grating sensor closely attached to its inner side. When the flexible cable is compressed or bent, it can absorb destructive stress, protecting the fiber Bragg grating sensor from breakage; at the same time, it can also serve as an excellent stress transmission medium, transferring micro-deformation to the fiber Bragg grating sensor, resulting in a stress response time ≤8ms and a micro-deformation sensitivity of 0.01%FS.

[0026] It should also be noted that in conventional cable design and material selection, there is a significant "seesaw effect" between the "physical buffering" and "flame retardancy and heat insulation" of materials. In current technology, to protect the fragile, outward-moving fiber Bragg grating sensor from mechanical compression, conventional improvements involve using elastomers such as rubber, silicone, or polyurethane as a buffer layer. However, these organic buffer materials generally suffer from the fatal flaws of being "flammable and lacking heat insulation." This not only leads to a significant decrease in the overall flame retardancy of the cable, but their high thermal conductivity or thermal instability also fails to effectively prevent heat loss, making the temperature sensor highly susceptible to interference from the external ambient temperature, resulting in completely distorted temperature measurements.

[0027] Conversely, if the goal is to achieve high flame retardancy and thermal stability in cables, the conventional approach is to fill them with large amounts of inorganic flame-retardant powder (such as simple magnesium hydroxide or aluminum oxide). However, common knowledge in the field indicates that these conventional inorganic flame-retardant materials are "highly hard and lack resilience," resulting in a rigid texture after extrusion molding. If these materials are placed around fiber Bragg grating sensors, they not only fail to provide flexible deformation absorption space for the sensors but also create "rigid compression" when the cable is under pressure or undergoes complex bending, directly causing the fiber Bragg grating sensors placed close to them to break and be damaged.

[0028] More importantly, silicate additives (such as sodium silicate) are generally used as rigid binders in conventional industrial understanding. People skilled in the art usually believe that mixing them with metal oxides (such as alumina) and inorganic hydroxides (such as magnesium hydroxide) will only result in a harder and more brittle solid. Therefore, there is no motivation to try this combination of purely inorganic materials to obtain a flexible cushioning effect.

[0029] However, through extensive creative experiments, it was discovered that when the mass ratio of metal oxides, inorganic hydroxides, and silicate additives is (4–6):(2–4):(1.5–2.5), the silicate additives form a unique microscopic flexible skeletal network during the crosslinking process. This formulation completely overcomes the inherent contradiction between conventional inorganic flame-retardant materials ("high hardness, no rebound") and organic cushioning materials ("flammable, non-insulating"). It not only retains the excellent properties of pure mineral materials—non-toxic, Class A flame-retardant, and ultra-low thermal conductivity of 0.082 W / (m·K)—but also produces unexpectedly high elasticity (compression rebound rate ≥92%).

[0030] In an alternative embodiment, the conductor core 11 is formed by stranding multiple copper-magnesium alloy wires and oxygen-free copper wires, with a mass ratio of copper-magnesium alloy wires to oxygen-free copper wires of 1:1 to 7 (specifically, 1:1, 1:3, 1:5, or 1:7). The stranding pitch of the conductor core 11 is 10-12 times the diameter of the conductor core 11. The conductor core 11 is stranded in a regular stranding pattern, with adjacent layers stranded in opposite directions. This improves the compactness of the conductor core 11 structure, preventing loose strands and broken wires during subsequent extrusion or wrapping processes. Furthermore, the opposite direction of adjacent layers can offset internal stress during bending, giving the flexible cable good flexibility. The bending radius can be reduced to 4 times the cable diameter, adapting to complex laying environments. Simultaneously, it also makes the conductor surface round, helping to reduce surface electric field distortion.

[0031] It should be noted that in the field of cable conductor technology, there has long been an inherent technical contradiction: to improve the tensile strength of the conductor, high-strength materials such as copper-magnesium alloys are usually used, but this inevitably leads to a significant decrease in conductivity (typically 5-20%); while to maintain high conductivity, pure copper conductors must be used, but their low tensile strength makes them unsuitable for demanding conditions such as large spans and high-frequency bending. Furthermore, using a single large-diameter copper-magnesium alloy wire severely reduces the cable's flexibility (decreases bending life), while pure copper wire, although flexible, is prone to breakage. Therefore, those skilled in the art generally hold the technical bias that "strength and flexibility are mutually exclusive" and "strength and conductivity are mutually exclusive."

[0032] To overcome the limitations of existing understanding, extensive experimental research revealed that an exceptionally superior "self-synergistic effect" can only be achieved when the proportion of copper-magnesium alloy wire is controlled between 1 / 8 and 1 / 2 (i.e., a mass ratio of 1:1 to 7), coupled with a stranding pitch of 10-12 times the diameter. Specifically, the copper-magnesium alloy wire provides high tensile strength (≥280MPa), while the oxygen-free copper wire ensures low resistance in the current transmission path (≤0.0172Ω·mm² / m). Simultaneously, this specific pitch ensures coordinated deformation of the two different metal wires during bending, avoiding internal stress concentration caused by differences in material elastic moduli. Experimental data demonstrates that this specific ratio structure achieves a 36.6% increase in tensile strength without any decrease in conductivity, and an 87.5% increase in bending life. Specific performance comparison data are shown in Table 1 below.

[0033] More importantly, the composite conductor core 11 is not isolated, but forms a "cross-layer" synergistic linkage with the specific 5:3:2 mineral filling layer 2 and monitoring layer 16. Specifically, because fiber Bragg grating sensors are extremely sensitive to micro-strain and easily damaged, if the conductor core 11 is made of conventional pure copper, it is prone to irreversible "plastic tensile deformation" under tension, which will directly lead to permanent baseline drift or even forced breakage of the fiber Bragg grating sensor. In this embodiment, the aforementioned 1:3-5 ratio composite conductor core 11 provides tensile strength and elastic recovery performance, forming a "mechanical linkage of an inner elastic skeleton and an outer flexible buffer" with the external 5:3:2 filling layer 2, which has a high compression recovery rate of ≥92%, ensuring that the flexible cable only undergoes coordinated elastic deformation under complex stress. This not only completely avoids the risk of fiber Bragg grating sensor breakage, but also ensures that external stress can be transmitted to the fiber Bragg grating sensor with high fidelity (stress response ≤8ms). Meanwhile, the specific composition and structural design of the conductor core 11 reduces its transmission loss by 33%, significantly reducing the reactive heat generation of the conductor from the source. In addition, the extremely low thermal conductivity (0.082 W / (m·K)) of the external 5:3:2 filling layer 2 effectively avoids the temperature field disorder caused by intense heat generation inside the flexible cable, giving the temperature sensor a stable thermodynamic monitoring environment.

[0034] In a practical application, the core unit 1 is multi-stranded, and the multi-strand core units 1 are twisted together to form the cable core. The filler layer 2 fills the gaps between the cable cores and covers the outside of the cable core. In this scheme, by using multi-strand core units 1 to form the cable core, the flexibility of the flexible cable and the stability of the internal structure can be improved. It should be noted that under complex bending conditions, strong internal compression and relative friction will inevitably occur between the multi-stranded core units 1, which can easily lead to pressure damage to the fiber optic grating sensor arranged outside the shielding layer 15. However, in this embodiment, since the filler layer 2 is used to fill the gaps between the cable cores, it utilizes the ultra-high compression resilience of the filler layer 2 (≥92%) to provide buffering between the individual core units 1. In this way, not only is the entire flexible cable rounded (good extrusion molding), but rigid compression and friction damage between the core units 1 are also avoided.

[0035] In one embodiment, a semi-conductive shielding layer 14 is further provided between the insulation layer 13 and the shielding layer 15. The thickness of the semi-conductive shielding layer 14 is 0.1-0.15 mm, which is used to eliminate the electric field distortion between the insulation layer 13 and the shielding layer 15, thereby improving the insulation performance and operational stability of the flexible cable. In particular, when the semi-conductive shielding layer 14 is used in conjunction with the aforementioned conductor core 11, it helps to further eliminate the electric field distortion between the insulation layer 13 and the shielding layer 15. The shielding layer 15 adopts a double-layer shielding structure, with an inner layer being a metal foil shielding layer with a thickness of 0.06-0.15 mm and an outer layer being a metal wire braided shielding layer with a braiding density of not less than 90%. The material of the metal foil shielding layer can be selected from aluminum foil, copper foil, copper-clad aluminum foil, stainless steel foil, amorphous alloy foil, or a composite shielding film composed of the above-mentioned metals and polyester film (e.g., aluminum-plastic composite tape or copper-plastic composite tape). The material of the metal wire braided shielding layer can be selected from at least one of tin-plated copper wire, bare copper wire, and copper alloy wire. By employing a double-layer shielding structure, external electromagnetic interference can be effectively resisted, and signal transmission attenuation can be reduced.

[0036] The fire-resistant layer 12 is a mica tape wrapping layer with an overlap rate ≥50% and a thickness of 0.15-0.25mm. Specifically, this mica tape uses ceramicized mica tape, which can form a dense ceramic layer at high temperatures, providing fireproof and thermal insulation. The insulation layer 13 is a cross-linked polyethylene (XLPE) extrusion layer with a thickness of 0.8-1.2mm. Specifically, silane cross-linked polyethylene material can be used, with a temperature resistance rating ≥125℃, a breakdown strength ≥25kV / mm, and is free of halogens and heavy metals. The flame-retardant layer 3 is a glass flame-retardant tape wrapping layer with an overlap rate ≥40% and a thickness of 0.2-0.3mm, which can effectively prevent the spread of flames and achieve a flame-retardant rating of Class A. The sheath layer 4 is a low-smoke, halogen-free polyolefin extrusion layer with a thickness of 1.0-1.5mm. It uses bio-based modified low-smoke, halogen-free polyolefin material, which releases no toxic gases during combustion, has low smoke density, and is biodegradable, meeting green environmental protection requirements. It also possesses excellent oil resistance, ozone resistance, and weather resistance, adapting to extreme climatic conditions. In practical applications, the surface of sheath layer 4 can be textured with anti-slip patterns and contains UV stabilizers to effectively prevent slippage during cable laying, improve the cable's UV resistance, and extend its outdoor service life.

[0037] To further verify the technical effect of the specific ratio of filler layer 2 in this embodiment, comparative experiments were conducted on the flexible cable in this embodiment. Test data shows that its thermal conductivity is as low as 0.082 W / (m·K), improving the thermal insulation performance by 45% compared to conventional single filler, effectively reducing conductor temperature rise and increasing cable current carrying capacity; its limiting oxygen index is ≥42%, its flame retardant rating reaches Class A with no dripping during combustion, and its smoke density is ≤15, far superior to conventional fillers; the compression resilience of filler layer 2 is ≥92%, breaking the limitation of conventional fillers lacking flexibility, providing flexible buffering for monitoring layer 16, effectively preventing damage to the fiber optic grating sensor under pressure; in addition, it possesses ultra-high temperature thermal stability, with a thermal stability temperature ≥380℃, and does not decompose or pulverize in high-temperature environments, ensuring the structural stability of the flexible cable during long-term operation. Specific performance comparison data are shown in Table 2 below:

[0038] To further verify the technical effectiveness of monitoring layer 16, comparative experiments were conducted on the flexible cable in this embodiment. The test data in Table 2 demonstrates that the temperature sensor's measurement error is only ±0.5℃, a 4-fold improvement in accuracy compared to conventional arrangements; the fiber optic grating sensor's response time to stress and vibration is reduced to ≤8ms, with a sensitivity as high as 0.01%FS, a 10-fold improvement compared to conventional solutions; the crosstalk value of the monitoring signal is as low as ≤-65dB, a 20dB improvement compared to conventional cables, avoiding signal distortion in strong electromagnetic environments; and the end-to-end network latency of the 5G wireless transmission module is controlled to ≤10ms, meeting the requirements for industrial real-time control.

[0039] The specific performance comparison data is shown in Table 3 below:

[0040] Figure 2 A method for manufacturing the aforementioned flexible cable is shown. The method includes: S10: Prepare conductor core 11, and cover it with fire-resistant layer 12, insulation layer 13, shielding layer 15 and monitoring layer 16 in sequence to obtain wire core unit 1. The monitoring layer 16 includes fiber optic grating sensor, temperature sensor and signal transmission module for transmitting the data obtained by fiber optic grating sensor and temperature sensor to external terminal. S20: One or more strands of wire core unit 1 are stranded together, and a filling layer 2 is extruded on the outside of it. The filling layer 2 is made by mixing metal oxide, inorganic hydroxide and silicate additive in a mass ratio of (4~6):(2~4):(1.5~2.5). S30: The flame-retardant layer 3 and the sheath layer 4 are sequentially wrapped around the outside of the filler layer 2.

[0041] The above preparation method is simple and can avoid damage to the components in the monitoring layer 16 caused by the heavy mechanical stress of subsequent cable making.

[0042] In practical applications, step S10 specifically includes: S11: Preparation of conductor core 11: Mix copper-magnesium alloy wire and oxygen-free copper wire according to a preset mass ratio, and use a regular stranding method to control the stranding pitch to be 10-12 times the diameter of conductor core 11 to make conductor core 11. During the stranding process, control the tension to be uniform to avoid wire breakage and loose strands in conductor core 11. S12: Refractory layer 12 wrapping: Ceramicized mica tape is wrapped around the outer layer of conductor core 11, controlling the wrapping overlap rate to be ≥50%, the thickness to be 0.15-0.25mm, and the wrapping speed to be 35-40 meters / minute, ensuring that the wrapping is tight and wrinkle-free; S13: Extrusion of insulation layer 13: Add silane cross-linked polyethylene material to the extruder, set the machine body temperature to 165-175℃ in zone 1, 170-180℃ in zone 2, and 175-185℃ in zone 3, and the die head temperature to 182-192℃. Feed the conductor core 11 wrapped with refractory layer 12 into the extruder and extrude to form insulation layer 13 with a thickness controlled at 0.8-1.2mm. After extrusion, cross-link it through an irradiation cross-linking machine, set the light intensity to 80-90%, and the wire output speed to 35-45m / min. S14: Preparation of semiconductive shielding layer 14 and shielding layer 15: A semiconductive shielding layer 14 with a thickness of 0.1-0.15 mm is extruded over the outer layer of insulating layer 13. Subsequently, a metal foil shielding layer and at least one braided shielding layer selected from tin-plated copper wire, bare copper wire, and copper alloy wire are wrapped around it in sequence. The thickness of the metal foil shielding layer is 0.08-0.12 mm, and the braiding density of at least one braided shielding layer selected from tin-plated copper wire, bare copper wire, and copper alloy wire is ≥90%. S15: Installation of monitoring layer 16: Distribute fiber optic grating sensors are embedded in the outer layer of shielding layer 15, and temperature sensors are evenly arranged in preset positions. Electrically connect the fiber optic grating sensors, temperature sensors and signal transmission module to complete the installation of monitoring layer 16. In step S20, the "extrusion filling layer 2" specifically involves: mixing alumina, magnesium hydroxide and sodium silicate evenly according to a preset ratio, adding them to an extruder, and extruding them onto the outer layer of the monitoring layer 16 to form the filling layer 2, ensuring that the filling is dense and the structure is round. Step 30 specifically includes: S31: Flame retardant layer 3 wrapping: The flame retardant wrapping tape is wrapped around the outer layer of the filler layer 2, and the wrapping overlap rate is controlled to be ≥40%, the thickness is 0.2-0.3mm, and the wrapping speed is synchronized with the extrusion speed; S32: Extrusion of sheath layer 4: Bio-based modified low-smoke halogen-free polyolefin material is added to the extruder. The machine body temperature is set to 85-90℃ in zone 1, 105-110℃ in zone 2, and 130-135℃ in zone 3. The die head temperature is 135-140℃. The cable core wrapped with flame-retardant layer 3 is fed into the extruder and extruded to form sheath layer 4. The thickness is controlled at 1.0-1.5mm. After extrusion, it is cooled and shaped to obtain the final soft cable.

[0043] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A flexible cable, characterized in that, include: At least one core unit, each core unit comprising, from the inside out, a conductor core, a fire-resistant layer, an insulation layer, a shielding layer and a monitoring layer, wherein the monitoring layer comprises a fiber optic grating sensor, a temperature sensor and a signal transmission module for transmitting the data obtained by the fiber optic grating sensor and the temperature sensor to an external terminal; A filler layer, which encapsulates at least one wire core unit; the filler layer is made by mixing metal oxide, inorganic hydroxide and silicate additive in a mass ratio of (4-6):(2-4):(1.5-2.5); A flame-retardant layer and a sheath layer are sequentially wrapped around the filler layer.

2. The flexible cable as described in claim 1, characterized in that, The conductor core is made of multiple copper-magnesium alloy wires twisted together with oxygen-free copper wires, and the mass ratio of the copper-magnesium alloy wires to the oxygen-free copper wires is 1:1 to 7.

3. The flexible cable as described in claim 2, characterized in that, The stranding pitch of the conductor core is 10-12 times the diameter of the conductor core.

4. The flexible cable as described in claim 3, characterized in that, The conductor core is stranded in a regular stranding manner, with adjacent layers stranded in opposite directions.

5. The flexible cable as described in claim 1, characterized in that, The core unit is composed of multiple strands, which are twisted together to form a cable core. The filling layer fills the gaps in the cable core and covers the outside of the cable core.

6. The flexible cable as described in claim 1, characterized in that, The fiber Bragg grating sensors are arranged in a distributed manner, with a spacing of 1-2m between two adjacent fiber Bragg grating sensors.

7. The flexible cable as described in claim 1, characterized in that, A semi-conductive shielding layer is further provided between the insulating layer and the shielding layer, and the thickness of the semi-conductive shielding layer is 0.1-0.15 mm.

8. The flexible cable as described in claim 1, characterized in that, The shielding layer adopts a double-layer shielding structure, wherein the inner layer is a metal foil shielding layer with a thickness of 0.06 to 0.15 mm, and the outer layer is a metal wire braided shielding layer with a braiding density of not less than 90%, wherein the metal wire is at least one of tin-plated copper wire, bare copper wire, and copper alloy wire.

9. The flexible cable as described in claim 6, characterized in that, The fire-resistant layer is a mica tape wrapping layer with a wrapping overlap rate of ≥50% and a thickness of 0.15-0.25mm; the insulation layer is a cross-linked polyethylene extrusion layer with a thickness of 0.8-1.2mm; the flame-retardant layer is a glass flame-retardant tape wrapping layer with a wrapping overlap rate of ≥40% and a thickness of 0.2-0.3mm; the sheath layer is a low-smoke halogen-free polyolefin extrusion layer with a thickness of 1.0-1.5mm.

10. A method for preparing a flexible cable as described in any one of claims 1-9, characterized in that, The preparation method includes: S10: Prepare a conductor core and cover it with a fire-resistant layer, an insulating layer, a shielding layer and a monitoring layer in sequence to obtain a wire core unit; S20: One or more strands of wire core unit are stranded together and a filler layer is extruded on the outside of them. The filler layer is made by mixing metal oxide, inorganic hydroxide and silicate additive in a mass ratio of (4-6):(2-4):(1.5-2.5). S30: A flame-retardant layer and a sheath layer are sequentially wrapped around the outside of the filler layer.

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