An enhanced crosslinked polyethylene cable and its extrusion production method

Abstract

The application relates to the technical field of crosslinked polyethylene cables, in particular to a reinforced crosslinked polyethylene cable and an extrusion molding production method thereof, which comprises a center conductor, a center insulating layer, a shielding layer, an inner protective layer and an outer protective layer arranged in sequence from inside to outside; the center conductor is provided with a hollow structure, an expanded heat dissipation reinforcing layer is filled in the center cavity of the center conductor, and a phase change heat dissipation layer is arranged between the center conductor and the center insulating layer; a flexible buffer isolation layer is arranged between the center insulating layer and the shielding layer, and the flexible buffer isolation layer is wrapped on the outer sidewall of the center insulating layer. The center conductor of the application adopts a hollow structure, is matched with the expanded heat dissipation reinforcing layer and the phase change heat dissipation layer. The heat conduction channel formed by the expanded graphite and nanofiber particles can quickly dissipate heat, the expanded heat dissipation reinforcing layer can also automatically adjust with temperature, the center conductor is effectively prevented from overheating, the service life of the cable is prolonged, and the stable operation of the cable in a high-load and high-temperature scene is ensured.

Description

Technical Field

[0001] This invention relates to the field of cross-linked polyethylene cable technology, and in particular to a reinforced cross-linked polyethylene cable and its extrusion molding production method. Background Technology

[0002] In the field of power transmission, cross-linked polyethylene cables are widely used in urban power grids, industrial power transmission, and other scenarios due to their good insulation properties, light weight, and relatively simple manufacturing process.

[0003] However, key issues such as the mechanical properties and safe heat dissipation of cables have long remained unresolved, significantly limiting their performance and operational reliability. Taking a high-temperature resistant multifunctional cable described in patent CN119650178A as an example, it exhibits the following drawbacks in practical use:

[0004] First, it requires a dedicated cooling system, which is complex and has poor reliability. Combining air and water cooling adds many components, significantly increasing structural complexity and cost. Furthermore, leaks in the water cooling pipes can easily lead to heat dissipation failure and short circuits.

[0005] Second, the heat dissipation is not targeted enough. The heat pipe layout is simple and cannot quickly dissipate heat from hot areas, making it difficult to adapt to complex operating environments.

[0006] Third, its detection capabilities are limited. Ultrasonic testing can only detect surface defects, is ineffective at detecting internal faults, and its accuracy is easily affected by environmental factors.

[0007] In addition, traditional cross-linked polyethylene cables rely on natural air heat dissipation, which has extremely low heat dissipation efficiency, resulting in a large amount of heat accumulation, accelerating insulation aging, and causing short circuit faults. This problem is particularly prominent in high-load, high-temperature, and space-constrained scenarios.

[0008] In summary, existing cross-linked polyethylene cable technology has many shortcomings and is difficult to meet the needs of power transmission in complex environments. Based on this, the present invention designs and develops an enhanced cross-linked polyethylene cable and its extrusion molding production method to better solve the problems existing in the prior art. Summary of the Invention

[0009] To solve one of the above-mentioned technical problems, the present invention adopts the following technical solution: a reinforced cross-linked polyethylene cable, comprising a central conductor, a central insulation layer, a shielding layer, an inner sheath, and an outer sheath arranged sequentially from the inside out;

[0010] The central conductor is hollow, and an expansion heat dissipation enhancement layer is filled in the central cavity of the central conductor. A phase change heat dissipation layer is disposed between the central conductor and the central insulation layer.

[0011] A flexible buffer isolation layer is provided between the central insulation layer and the shielding layer, and the flexible buffer isolation layer is wrapped around the outer wall of the central insulation layer.

[0012] In any of the above embodiments, it is preferred that the central conductor is hollow. During AC power transmission, the current will accumulate on the surface of the conductor, resulting in uneven current distribution inside the conductor. In this invention, setting the central conductor as a hollow structure can promote a more uniform distribution of current in the annular solid part of the central conductor, effectively reducing the impact of the skin effect. It reduces resistance loss during power transmission and can also improve the effective utilization rate of the central conductor, giving the entire cable better conductivity during AC power transmission. It is particularly suitable for high-frequency power transmission scenarios, such as the field of communication cables.

[0013] In any of the above embodiments, it is preferred that the expansion heat dissipation strengthening layer is composed of a blend of expanded graphite particles and nanofiber particles; the expansion heat dissipation strengthening layer fills 80%-90% of the central cavity of the central conductor.

[0014] When expanded graphite particles and nanofiber particles are blended together, they can interweave into a network structure. The two work together to build a dense heat conduction channel. When the central conductor heats up, the heat is quickly absorbed by the expanded heat dissipation enhancement layer and the heat is accelerated to conduct radially. At the same time, the heat is quickly transferred to the entire conductor surface, accelerating heat dissipation and greatly reducing the accumulation of internal heat.

[0015] In any of the above solutions, it is preferable to control the filling rate at 80%-90% to ensure that the expansion heat dissipation reinforcement layer will not hinder expansion due to overfilling, nor will it reduce the heat dissipation effect due to thermal resistance caused by insufficient filling.

[0016] When the temperature of the central conductor rises, the volume of the expansion heat dissipation enhancement layer expands appropriately. On the one hand, it increases the contact area with the central conductor, improving heat conduction efficiency; on the other hand, the pore structure inside the expansion heat dissipation enhancement layer is compressed, gas flow is obstructed, reducing axial heat convection loss, achieving efficient heat dissipation through radial heat conduction, and effectively preventing the conductor from aging prematurely due to overheating.

[0017] It should be explained that traditional air-cooled cables rely primarily on air as the heat transfer medium, but air has a thermal conductivity of only 0.026 W / (m·K), resulting in extremely low heat transfer efficiency. In contrast, the expanded graphite particles within the central conductor of this invention have a thermal conductivity of 150-600 W / (m·K). These particles intertwine with nanofiber particles to form a mesh, and work in conjunction with the expanded graphite to create dense heat transfer channels, significantly improving heat transfer efficiency and accelerating the transfer of heat from the central conductor to the conductor surface.

[0018] Furthermore, traditional cables cannot adjust heat dissipation according to changes in the temperature of the central conductor; once the conductor temperature rises, heat dissipation efficiency is difficult to improve. The expansion heat dissipation reinforcement layer of the cable in this invention expands as the conductor temperature rises, increasing the contact area with the central conductor and enhancing heat conduction; simultaneously, it compresses internal pores, reducing heat convection loss, achieving adaptive and efficient heat dissipation, and effectively preventing overheating of the central conductor.

[0019] From the perspective of structural reinforcement:

[0020] First, the addition of nanofiber particles enhances the overall strength and toughness of the expansion heat dissipation reinforcement layer; during cable laying and installation, it can effectively resist external pressure and impact, protect the central conductor from damage, and extend the service life of the cable.

[0021] Secondly, the expansion heat dissipation reinforcement layer fills the central cavity of the central conductor, which provides a certain support for the conductor, helps to maintain the shape stability of the conductor, and prevents the conductor from deforming due to external forces, thus affecting the electrical performance of the cable.

[0022] The expansion heat dissipation reinforcement layer can automatically adjust its heat dissipation performance according to the temperature change of the central conductor; it maintains a stable filling state when the temperature is low; when the temperature rises, the internal structure expands rapidly to enhance heat dissipation capacity and realize intelligent heat dissipation management, which is a self-regulating heat dissipation function that conventional cables do not have.

[0023] The composite network structure composed of expanded graphite particles and nanofiber particles has a certain thermal energy storage capacity; when the temperature of the central conductor rises rapidly, it can absorb and store some heat, slow down the rate of temperature rise of the central conductor, buy time for heat dissipation, effectively protect the insulation material inside the cable, and realize the thermal energy storage function.

[0024] The cable structure of this invention is applicable to various application scenarios: First, high-load power transmission scenarios. In places requiring the transmission of large amounts of electrical energy, such as the main lines of urban power grids and large substations in industrial enterprises, cables are typically under high load and easily generate a large amount of heat. The cable's efficient heat dissipation performance and self-regulating heat dissipation function ensure stable operation under high loads and reduce the risk of failure due to overheating. Second, high-temperature environments. In high-temperature operating environments such as steel mills, glass factories, and boiler rooms, cables not only have to withstand their own heat generation but also face the test of external high temperatures. The cable's expansion heat dissipation reinforcement layer can effectively dissipate heat in high-temperature environments, ensuring normal operation of the cable and improving its adaptability to harsh environments. Third, space-constrained scenarios. In some space-constrained locations, such as underground tunnels and building shafts, the laying and maintenance space for cables is limited. The cable's excellent mechanical properties and stable structural support can reduce cable damage caused by external pressure, lower maintenance costs, and improve the reliability of the cable in space-constrained scenarios.

[0025] In any of the above embodiments, it is preferred that the flexible buffer isolation layer includes a flexible rubber body, and a plurality of aerogel particles are filled and mixed inside the flexible rubber body, and the aerogel particles are fixed to the flexible rubber body by an adhesive.

[0026] The flexible buffer layer functions as follows: When the cable is subjected to bending, stretching, or vibration, the cross-linking points between the molecular chains of the flexible rubber matrix begin to function, limiting excessive slippage of the molecular chains. Simultaneously, the polymer chains themselves gradually extend along the direction of force, converting the mechanical energy generated by the external force into the elastic potential energy of the molecular chains. Taking bending stress as an example, when the cable bends, the outer side of the flexible rubber matrix is ​​under tension, while the inner side is under compression. The outer polymer chains extend under tension, absorbing tensile energy; the inner polymer chains further curl under pressure, buffering the pressure, thereby effectively dispersing and alleviating bending stress and preventing stress concentration from damaging the internal structure of the cable. Furthermore, the viscoelasticity of the flexible rubber causes internal friction during vibration, converting vibrational mechanical energy into heat energy, thus attenuating vibrational energy and reducing mechanical fatigue of the cable.

[0027] Furthermore, when heat is transferred from the central insulation layer to the shielding layer, the aerogel particles form tiny heat-insulating units within the flexible rubber matrix. Heat must be reflected and scattered multiple times within the pores of the aerogel particles before it can continue to be transferred, effectively blocking heat conduction. Due to the uniform dispersion of the aerogel particles, a relatively stable temperature gradient is formed between the central insulation layer and the shielding layer, preventing adverse effects on cable performance caused by temperature fluctuations.

[0028] In any of the above embodiments, it is preferred that a plurality of intelligent temperature-sensing layers are provided at intervals along the extension direction of the outer protective layer, the intelligent temperature-sensing layer comprising a thermochromic ink coating surrounding the outer wall of the outer protective layer, the interval between adjacent thermochromic ink coatings being 0.5m-1m.

[0029] When a cable experiences overload, partial short circuit, or other faults, the temperature at the fault point rises rapidly. The temperature-sensitive color-changing ink coating of the intelligent temperature-indicating layer can respond promptly to temperature changes, issuing an early warning signal through color changes. Because the spacing between adjacent temperature-sensitive color-changing ink coatings is 0.5m-1m, this design ensures precise location of the heat source, allowing maintenance personnel to detect anomalies in the early stages of a fault, take appropriate measures, prevent further escalation of the fault, and reduce maintenance costs and the risk of power outages.

[0030] In any of the above embodiments, it is preferred that the thickness of the thermochromic ink coating is 15μm-25μm, and the material of the thermochromic ink coating is selected as wear-resistant thermochromic ink.

[0031] Abrasion-resistant thermochromic inks possess excellent abrasion resistance, enabling them to withstand friction between cables and external objects during installation and use. In environments with frequent movement and vibration, ordinary thermochromic ink coatings may be damaged by abrasion, leading to temperature monitoring failure. Abrasion-resistant inks effectively reduce this risk, ensuring the thermochromic ink coating remains intact for an extended period, continuously providing maintenance personnel with accurate temperature information. In harsh environments, such as construction sites and mines, cables face even more severe abrasion challenges. Abrasion-resistant thermochromic ink coatings of 15μm-25μm can withstand the friction and impact under these complex operating conditions, ensuring normal cable temperature display even under extreme conditions, thus guaranteeing the safe operation of cables in harsh environments.

[0032] In any of the above embodiments, it is preferred that a reinforcing layer is wrapped around the outside of the flexible buffer isolation layer. When the reinforced cross-linked polyethylene cable is deformed by external force, the reinforcing layer and the flexible buffer isolation layer cooperate to realize the deformation recovery of the cable.

[0033] When a cross-linked polyethylene cable is subjected to an external impact, the copper-based shape memory alloy braided mesh, with its excellent flexibility and strength, responds rapidly and bears most of the external force. Its braided structure effectively disperses stress under load, preventing stress concentration in localized areas of the cable. Simultaneously, the flexible buffer layer, thanks to the high elasticity of its flexible rubber matrix, undergoes elastic deformation. The polymer chains within the rubber extend and slide during stress, converting some mechanical energy into internal energy, thus providing a buffering effect. For example, when the cable is accidentally dragged during installation, the flexible buffer layer can reduce the impact of tension on the reinforcing layer, preventing the copper-based alloy wires from breaking due to excessive stress.

[0034] In any of the above embodiments, it is preferred that the reinforcing layer includes a braided mesh structure wrapped around the central insulating layer, the braided mesh structure being woven from shape memory alloy wires.

[0035] The copper-based shape memory alloy wire mesh structure possesses a unique spatial configuration. The mesh exhibits more balanced mechanical properties in all directions, allowing for a rapid response when the cross-linked polyethylene cable is subjected to external impacts, whether from axial tension, radial pressure, or complex shear forces. The interwoven nodes between the alloy wires act as stress dispersion points, evenly dispersing concentrated external forces along the warp and weft directions of the mesh. For example, when the cable passes through a narrow conduit, if the conduit wall compresses the cable, the unique structure of the mesh ensures that the pressure is evenly distributed across the entire cable circumference, preventing localized stress that could lead to breakage or deformation of the copper-based alloy wires. Simultaneously, the flexible rubber core of the flexible buffer layer, acting as an intermediate medium for stress transmission, further buffers and disperses stress, preventing stress concentration from damaging the cable's internal central insulation and shielding layers.

[0036] In any of the above embodiments, it is preferred that the shape memory alloy wire is drawn from a copper-based shape memory alloy.

[0037] When cross-linked polyethylene cables are subjected to external forces such as bending, stretching, or compression, the copper-based shape memory alloy wires in the braided mesh structure undergo a rapid martensitic phase transformation due to stress stimulation. At the microscopic level, the crystal structure inside the alloy wire transforms from austenite to martensite, causing a change in the physical shape of the alloy wire. Simultaneously, the flexible rubber matrix of the flexible buffer layer, with its high elasticity, undergoes elastic deformation, absorbing and dispersing some of the external force. The viscoelasticity of the rubber matrix not only buffers the impact force but also reduces the local stress burden on the copper-based alloy wire braided mesh, effectively preventing damage to the alloy wires due to stress concentration and ensuring the integrity of the entire reinforcing structure under complex external forces.

[0038] In any of the above embodiments, it is preferred that the shielding layer includes a metal shielding mesh spirally wrapped around the outside of the central insulating layer, a metal foil wrapped around the outer layer of the metal shielding mesh, the metal foil and the metal shielding mesh being fixed together by adhesive and hot pressing, and a cross-linked polyethylene layer wrapped around the outside of the metal foil.

[0039] The double-layer structure of the metal shielding mesh and metal foil effectively shields against broadband electromagnetic interference. Working together, they compensate for the limitations of a single shielding layer in terms of frequency range, providing comprehensive electromagnetic protection for the cable's internal insulation and conductors, ensuring stable operation in complex electromagnetic environments. The metal foil and metal shielding mesh are bonded together with adhesive and thermoforming, forming a tightly integrated structure. This structure enhances the mechanical strength of the shielding layer, enabling it to withstand external forces such as tension, bending, and compression during cable laying and use. A cross-linked polyethylene layer wraps around the metal foil, further enhancing the shielding layer's abrasion resistance and impact resistance, protecting the metal shielding mesh and metal foil from external damage, and extending the shielding layer's service life. When the cable is subjected to external impact, the cross-linked polyethylene layer absorbs some energy, reducing the stress on the metal shielding mesh and metal foil, preventing damage to the shielding layer due to excessive external force, and ensuring the integrity of the cable's internal structure.

[0040] In any of the above embodiments, it is preferred to provide a grounding unit between the inner protective layer and the shielding layer. The grounding unit includes a grounding conductor, and an insulating and waterproof layer is formed on the outside of the grounding conductor.

[0041] As the core of the grounding unit, the grounding conductor provides a low-impedance discharge path for fault current when the cable experiences insulation failure or is struck by lightning. When abnormal current occurs inside the cable, the grounding conductor quickly diverts the current to the earth, preventing the fault current from damaging other parts of the cable, reducing safety risks caused by leakage, and effectively protecting the safety of personnel and equipment. During cable operation, the grounding conductor helps balance the potential distribution of different parts of the cable, preventing partial discharge or breakdown caused by excessive potential difference. Especially in high-voltage cable systems, a stable potential distribution is crucial for ensuring the long-term stable operation of the cable. In addition, the insulating and waterproof layer covering the outside of the grounding conductor effectively blocks moisture intrusion, preventing the grounding conductor from corroding due to moisture and ensuring the long-term stability of grounding performance. In humid environments, such as underground laying or underwater applications, the insulating and waterproof layer can prevent the increase in grounding resistance caused by moisture accumulation, ensuring the reliability of the grounding system. Isolating the grounding conductor from the surrounding metal shielding mesh and central insulation layer prevents short circuits or leakage accidents caused by improper electrical connections, further improving the safety of the cable system.

[0042] The grounding unit and the shielding layer work together to enhance the electromagnetic shielding effect of the cable. The grounding conductor can promptly introduce the electromagnetic interference current induced in the shielding layer into the ground, reducing the interference potential on the shielding layer and improving its shielding effectiveness. Simultaneously, the presence of the insulating and waterproof layer ensures electrical insulation between the grounding conductor and the shielding layer, preventing a decrease in shielding performance due to electrical connection between the two. The grounding unit between the inner sheath and the shielding layer can share some of the electrical stress on the central insulation layer, reducing its burden and extending its service life. The insulating and waterproof layer also provides additional protection for the central insulation layer, preventing damage caused by external factors.

[0043] This invention also provides a method for producing reinforced cross-linked polyethylene (XLPE) cables by extrusion molding, wherein the reinforced XLPE cable is as described above, and includes the following steps:

[0044] Preparation of the central conductor: The conductor material is processed into a hollow structure and a guide internal thread is made on its inner wall. An expansion heat dissipation strengthening layer is filled in the central cavity of the central conductor. The expansion heat dissipation strengthening layer is composed of a blend of expanded graphite particles and nanofiber particles, and the filling rate is controlled at 80%-90%. A phase change heat dissipation layer is set between the central conductor and the central insulation layer to be prepared later.

[0045] Processing the conductor material into a hollow structure and creating guiding internal threads on its inner wall can guide and distribute the conductor material during the filling of the expansion heat dissipation reinforcement layer, as detailed below:

[0046] Guiding the filling direction: The guide internal thread provides clear directional guidance for the filling of the expansion and heat dissipation strengthening layer material. During the filling process, the material will be evenly distributed on the inner wall of the hollow structure along the spiral direction of the internal thread, avoiding local accumulation or uneven distribution of the filling material, and helping to form a uniform heat dissipation expansion and heat dissipation strengthening layer.

[0047] Controlling the filler amount: The presence of internal threads can control the filler amount of the expansion heat dissipation reinforcement layer material to a certain extent. The space between each thread can accommodate a certain amount of filler material. By controlling the material feed rate and the number of thread turns during the filling process, the total amount of filler material can be controlled relatively precisely, ensuring that the heat dissipation expansion heat dissipation reinforcement layer meets the designed thickness and performance requirements.

[0048] Enhanced bonding: The threaded structure increases the contact area between the conductor's inner wall and the expansion heat dissipation reinforcement layer material. After the filler material enters the threaded gap, it forms a mechanical engagement with the inner wall. This engagement enhances the bonding force between the two, making the heat dissipation expansion heat dissipation reinforcement layer less likely to fall off or slide during use, thus improving the stability and reliability of the heat dissipation structure.

[0049] Promoting uniform material expansion: After filling, when the conductor heats up and causes the heat dissipation reinforcement layer material to expand, the internal threads can guide the material to expand uniformly in the radial and circumferential directions. The constraint effect of the threads makes the expansion of the material in all directions more coordinated, avoiding stress concentration caused by uneven expansion, thereby improving the overall performance and service life of the heat dissipation expansion reinforcement layer.

[0050] Extruded central insulation layer: Using an extrusion process, a central insulation layer is extruded on the outside of the central conductor after the expansion heat dissipation reinforcement layer and the phase change heat dissipation layer are set;

[0051] Fabrication of a flexible buffer layer: After the flexible rubber body and aerogel particles are mixed evenly with an adhesive, a wrapping process is used to form a flexible buffer layer on the outside of the central insulation layer.

[0052] Constructing the shielding layer: First, the metal shielding mesh is spirally wrapped around the outside of the central insulation layer, then metal foil is wrapped around the outer layer of the metal shielding mesh. The metal foil and the metal shielding mesh are fixed together by adhesive and hot pressing. Finally, a cross-linked polyethylene layer is extruded and coated on the outside of the metal foil.

[0053] Forming the outer sheath structure: During the extrusion molding process of the outer sheath, a temperature-sensitive color-changing ink coating is applied around its outer wall at intervals of 0.5m-1m to form an intelligent temperature-sensing layer; On the inner side of the outer sheath, a reinforcing layer made of shape memory alloy wire is wrapped around the outside of the flexible buffer isolation layer; A grounding unit is set between the inner sheath and the shielding layer, and the grounding conductor is covered with an insulating and waterproof layer and then installed in place; Finally, the inner sheath and the outer sheath are extruded to complete the extrusion molding of the reinforced cross-linked polyethylene cable.

[0054] This production method comprehensively considers the functional requirements of each part of the cable. Starting with the center conductor, the hollow structure, combined with the expansion heat dissipation reinforcement layer and the phase change heat dissipation layer, can effectively dissipate the heat generated during cable operation, preventing performance degradation or even damage due to heat accumulation. The central insulation layer ensures the electrical insulation performance of the cable, preventing safety accidents caused by current leakage. The flexible buffer isolation layer can buffer external impacts, protecting the internal structure from damage, while also providing some heat insulation and insulation. The shielding layer effectively blocks external electromagnetic interference, ensuring stable signal transmission within the cable. The intelligent temperature-sensing layer of the outer sheath can monitor the cable temperature in real time, issuing timely warnings when the temperature is abnormal; the reinforcement layer improves the cable's mechanical strength and resistance to deformation; and the grounding unit ensures the electrical safety of the cable, preventing hazards to personnel and equipment caused by leakage.

[0055] The cables produced using this method exhibit superior overall performance: the combined use of an expansion-type heat dissipation reinforcement layer and a phase-change heat dissipation layer significantly improves heat dissipation efficiency compared to traditional cables, enabling them to withstand higher power operating environments. The intelligent temperature-sensing layer provides the cable with self-monitoring and early warning functions, a feature absent in traditional cables, greatly enhancing the safety and reliability of cable operation. The shape memory alloy wire braided reinforcement layer not only improves the cable's mechanical strength but also endows it with a certain degree of self-healing capability; when the cable undergoes a certain degree of deformation, the shape memory alloy wires can return to their original shape, reducing the risk of cable damage.

[0056] In the process of preparing the central conductor, when the expanded graphite particles and nanofiber particles are blended, the expanded graphite particles and nanofiber particles are first pretreated to activate their surfaces and enhance the bonding force between them.

[0057] Pretreatment of expanded graphite particles and nanofiber particles to activate their surfaces increases the number of active groups on the particle surface. When the two are blended, these active groups can form stronger chemical bonds or physical adsorption forces, thereby enhancing their binding force. This results in a more compact and stable structure within the expanded heat dissipation enhancement layer, which is beneficial for rapid heat conduction. Simultaneously, the tighter bonding structure also improves the mechanical properties of the expanded heat dissipation enhancement layer, enabling it to better withstand the stress and vibration generated by the central conductor during operation.

[0058] After pretreatment, the heat dissipation performance of the expanded heat dissipation enhancement layer is greatly improved. Due to the tighter bonding between particles and the smoother heat conduction path, heat can be transferred from the central conductor to the outside more quickly. Furthermore, this tightly bonded structure makes the expanded heat dissipation enhancement layer less prone to particle shedding or structural loosening during long-term use, extending its service life. Compared to traditional heat dissipation materials, this pretreated expanded heat dissipation enhancement layer shows significant improvements in both heat dissipation efficiency and stability.

[0059] In the step of making the flexible buffer isolation layer, the adhesive is a two-component epoxy resin adhesive. Before mixing the flexible rubber body and aerogel particles, the two components of the adhesive are accurately mixed in proportion and thoroughly stirred.

[0060] Two-component epoxy resin adhesives possess excellent bonding properties and chemical stability. Accurately mixing the two components in the correct proportions and thoroughly stirring ensures optimal bonding performance. In the flexible buffer layer, the adhesive firmly bonds the flexible rubber substrate and aerogel particles together, forming a uniform whole. The aerogel particles, with their excellent thermal insulation properties, are evenly distributed throughout the flexible rubber substrate through the adhesive's fixation, effectively improving the thermal insulation effect of the flexible buffer layer. Simultaneously, the adhesive also enhances the strength and toughness of the flexible rubber substrate, enabling it to better buffer against external impacts.

[0061] In the process of constructing the shielding layer, the metal shielding mesh is woven from electrolytic copper wire with a weaving density of not less than 80%, and the metal shielding mesh is pre-stretched before spiral wrapping to improve its tensile strength.

[0062] Electrolytic copper wire possesses excellent conductivity and electromagnetic shielding properties. Using electrolytic copper wire to weave metal shielding mesh effectively blocks external electromagnetic interference. A weaving density of no less than 80% ensures the shielding effect, effectively shielding electromagnetic signals of different frequencies. Pre-stretching treatment makes the copper wires in the metal shielding mesh more evenly aligned in the stretching direction, increasing the contact area between the wires and thus improving the tensile strength of the metal shielding mesh. During cable installation and use, the metal shielding mesh can better withstand tensile forces, is less prone to breakage or deformation, and ensures the integrity and stability of the shielding layer.

[0063] In the step of forming the outer protective structure, the thermochromic ink coating is applied to the outer wall of the outer protective layer using a screen printing process. During the printing process, the temperature of the ink is controlled at 20℃-25℃ and the humidity is controlled at 40%-60% to ensure that the coating thickness is uniform and within the range of 15μm-25μm.

[0064] Screen printing ensures that the thermochromic ink coating is evenly applied to the outer wall of the outer sheath. Controlling the ink's temperature and humidity within a suitable range optimizes its flowability and drying speed, ensuring a uniform coating thickness within specified limits. This uniform coating thickness guarantees a more accurate and consistent temperature response from the thermochromic ink. When the cable temperature changes, the coating can promptly and accurately display the corresponding color change, enabling real-time monitoring of the cable temperature.

[0065] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0066] 1. The central conductor of this invention adopts a hollow structure, combined with an expansion heat dissipation reinforcement layer and a phase change heat dissipation layer. The heat conduction channel formed by the expanded graphite and nanofiber particles can dissipate heat quickly, and the expansion heat dissipation reinforcement layer can also automatically adjust with temperature, possessing a heat storage function, effectively preventing the central conductor from overheating, extending the cable life, and ensuring its stable operation in high-load, high-temperature scenarios.

[0067] 2. This invention enhances the strength and toughness of the expansion heat dissipation reinforcement layer by adding nanofiber particles, thus supporting the central conductor. The flexible buffer isolation layer and the reinforcement layer woven from shape memory alloy wires work together to effectively disperse stress, buffer external forces, and restore the cable shape, thereby improving the cable's mechanical strength and resistance to deformation. This makes it suitable for complex stress and space-constrained scenarios.

[0068] 3. The shielding layer of this invention is composed of a metal shielding mesh and metal foil, achieving broadband electromagnetic shielding. The grounding unit between the central insulation layer and the shielding layer can quickly discharge current in case of a fault, and the insulating and waterproof layer ensures stable grounding performance. The combination of the two enhances the electromagnetic shielding effect and ensures the safe and reliable operation of the cable.

[0069] 4. This invention incorporates an intelligent temperature-sensing layer in the outer sheath, composed of a temperature-sensitive color-changing ink coating. When the cable temperature rises abnormally, the coating changes color to issue an early warning. Optimal coating spacing and thickness allow for precise location of hot spots, facilitating timely handling by maintenance personnel and reducing losses from malfunctions.

[0070] 5. The cable structure design of this invention makes it suitable for various scenarios. It operates stably in high-load power transmission, high-temperature environments, and space-constrained scenarios, thanks to its advantages in heat dissipation and mechanical performance. Simultaneously, the materials of each structural layer are weather-resistant and corrosion-resistant, adapting to different environments and meeting complex application requirements. Attached Figure Description

[0071] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or components are generally identified by similar reference numerals. In the drawings, the elements or components are not necessarily drawn to scale.

[0072] Figure 1 This is a schematic diagram of the internal structure of the cable of the present invention.

[0073] Figure 2 This is a schematic diagram of the internal structure of the central conductor of the present invention.

[0074] In the diagram: 1. Center conductor; 101. Guide internal thread; 2. Center insulation layer; 3. Shielding layer; 301. Metal shielding mesh; 302. Metal foil; 303. Cross-linked polyethylene layer; 4. Inner protective layer; 5. Outer protective layer; 6. Expansion heat dissipation reinforcement layer; 7. Phase change heat dissipation layer; 8. Flexible buffer isolation layer; 9. Intelligent temperature display layer; 10. Reinforcement layer; 11. Grounding unit; 1101. Grounding conductor; 1102. Insulating and waterproof layer. Detailed Implementation

[0075] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore merely examples and should not be used to limit the scope of protection of the present invention. The specific structure of the present invention is as follows: Figures 1-2 As shown in the image.

[0076] Example 1:

[0077] I. Preparation of the central conductor:

[0078] 1. Material preparation: 99.95% pure oxygen-free copper rod is selected as the center conductor material. High-purity oxygen-free copper has good electrical and thermal conductivity, which can effectively reduce energy loss and heat generation during cable transmission.

[0079] Prepare expanded graphite particles with a diameter of 60-80 μm and nanofiber particles with a diameter of 80-150 nm and a length of 2-4 μm.

[0080] Expanded graphite has a unique layered structure that expands to form a worm-like structure when heated, greatly increasing its specific surface area and facilitating heat conduction and dissipation. Nanofiber particles, with their nanoscale size effect, can fill the gaps in expanded graphite particles, enhancing the overall structural stability and thermal conductivity.

[0081] 2. Particle pretreatment:

[0082] The expanded graphite particles are placed in a high-temperature furnace and baked at 320°C for 1.5 hours. This step removes moisture and impurities from the surface of the expanded graphite particles, improving their purity and activity.

[0083] Next, the particles are placed in a plasma treatment device, and argon and oxygen (volume ratio 4:1) are introduced and treated at 110 Pa for 12 minutes. Plasma treatment can generate a large number of active groups, such as hydroxyl and carboxyl groups, on the surface of expanded graphite particles. These active groups can react with the groups on the surface of nanofiber particles, thereby enhancing the bonding force between the two.

[0084] Nanofiber particles were reacted with a 2.5 mol / L nitric acid solution at 65°C with stirring for 2.5 hours. The oxidizing effect of the nitric acid solution can generate more oxygen-containing functional groups on the surface of the nanofiber particles, thereby increasing their surface activity.

[0085] Then rinse with deionized water until neutral, and dry at 85°C for 10 hours to remove moisture and ensure the stability of the nanofiber particles.

[0086] 3. Center conductor processing:

[0087] Oxygen-free copper rods are processed into hollow structures using a continuous extrusion press, with the hollow diameter being 1 / 4 of the outer diameter.

[0088] The hollow structure not only reduces the weight of the cable, but also provides space for the expansion and heat dissipation reinforcement layer.

[0089] Pretreated expanded graphite particles and nanofiber particles were mixed at a mass ratio of 6:4 using a screw feeder and filled into the central cavity, with a filling rate of 82%.

[0090] This fill ratio ensures that the expansion heat dissipation reinforcement layer has sufficient heat dissipation capacity without causing excessive internal pressure due to overfilling, which could affect cable performance. After filling, both ends are sealed to prevent material leakage from the expansion heat dissipation reinforcement layer.

[0091] 4. Phase change heat dissipation layer setup:

[0092] A 0.6 mm thick layer of phase change material is applied to the outside of the central conductor. The phase change material is a blend of stearic acid and low-density polyethylene (mass ratio 5:5).

[0093] Phase change materials (PCMs) undergo a phase transition when the temperature changes, absorbing or releasing a large amount of latent heat, thereby regulating the temperature. Stearic acid has a suitable phase transition temperature range, while low-density polyethylene can enhance the stability and mechanical properties of PCMs.

[0094] A hot-pressing process is used to tightly bond it to the central conductor, ensuring that the phase change material can effectively absorb and transfer the heat generated by the central conductor.

[0095] II. Extrusion of the central insulation layer:

[0096] 1. Preparation of insulation materials:

[0097] Cross-linked polyethylene insulation material is used, with a density of 0.93 g / cm³ and a melt flow rate of 1.2 g / 10 min.

[0098] Cross-linked polyethylene (XLPE) possesses excellent electrical insulation, heat resistance, and mechanical properties, making it an ideal material for cable insulation. It is dried in an 85°C dryer for 3.5 hours to remove moisture, as moisture can negatively impact the insulation material's performance and reduce its insulating effect.

[0099] 2. Extrusion molding:

[0100] Using a single-screw extruder (screw diameter 100mm, length-to-diameter ratio 22:1), the temperatures of each zone were set to 135℃, 155℃, 175℃, 185℃, and 195℃.

[0101] This temperature setting allows the insulation material to be fully plasticized during extrusion, ensuring uniform quality of the insulation layer. The center conductor is fed into the die head, and the insulation material is wrapped at a speed of 18 m / min. After extrusion, it is cooled and shaped in a 22°C cooling water bath. Appropriate extrusion speed and cooling temperature allow the insulation layer to form quickly, avoiding defects such as deformation and bubbles.

[0102] III. Fabrication of a flexible buffer isolation layer:

[0103] 1. Material preparation:

[0104] Nitrile rubber is selected as the flexible rubber body. Nitrile rubber has good oil resistance, abrasion resistance, and flexibility, which can effectively buffer external impact forces. The aerogel particles have a particle size of 20-40μm. Aerogel is a material with extremely low density and high porosity, and has excellent thermal insulation properties.

[0105] Two-component epoxy resin adhesive is selected:

[0106] 1. Component A: Bisphenol A type epoxy resin E-51, which has good adhesion, chemical corrosion resistance and mechanical properties, and is a commonly used type of epoxy resin.

[0107] 2. Component B: Polyamide 650 curing agent. When polyamide curing agents are used in combination with epoxy resin, the reaction is mild, and the cured product has good toughness and water resistance. Components A and B are prepared in a 3:1 mass ratio.

[0108] 2. Adhesive preparation:

[0109] Stir components A and B separately at 28°C for 8 minutes each. Then pour component A into component B and stir at 550 rpm for 18 minutes. Precise control of temperature, stirring time, and speed ensures thorough mixing of components A and B, allowing the adhesive to achieve optimal bonding performance.

[0110] 3. Mixing and wrapping:

[0111] Plasticizing the flexible rubber matrix in an open mill for 12 minutes can break the molecular chains of the rubber, reduce its viscosity, and improve its plasticity and processing performance.

[0112] Aerogel particles and binder are added and mixed for 22 minutes to ensure the aerogel particles are evenly dispersed in the flexible rubber matrix. The mixture is then calendered into a 1.2mm sheet and spirally wrapped around the outside of the central insulation layer with a 35% overlap. Appropriate sheet thickness and overlap ensure the integrity and cushioning effect of the flexible buffer layer.

[0113] IV. Constructing a shielding layer:

[0114] 1. Preparation of metal shielding mesh:

[0115] Electrolytic copper wire (0.12mm in diameter) is used to weave the metal shielding mesh, with a weaving density of 88%.

[0116] Electrolytic copper wire possesses high purity and excellent conductivity, effectively shielding against electromagnetic interference. A higher weaving density enhances the shielding effect of the mesh. Pre-stretching is performed using a stretching machine with a tensile force of 60N for 8 minutes.

[0117] Pre-stretching can make the copper wires more neatly arranged in the stretching direction, increase the contact area between the copper wires, and thus improve the tensile strength and shielding performance of the metal shielding mesh.

[0118] 2. Construction of the shielding layer:

[0119] The metal shielding mesh is wrapped around the flexible buffer isolation layer at a 90mm pitch. The appropriate wrapping pitch can ensure the coverage effect and flexibility of the shielding mesh.

[0120] Then, a 0.12mm thick aluminum foil is wrapped around it. The aluminum foil has good conductivity and shielding properties, which can further enhance the shielding effect. The aluminum foil is then hot-pressed at 130℃ and 6MPa pressure for 8 minutes to bond it to the metal shielding mesh with adhesive.

[0121] The hot-pressing process tightly bonds the aluminum foil and the metal shielding mesh, forming a complete shielding layer. Finally, a cross-linked polyethylene layer is extruded and coated, using the same process as the central insulation layer. This cross-linked polyethylene layer protects the shielding layer from external environmental influences, improving its stability and service life.

[0122] V. Formation of the outer protective structure:

[0123] 1. Intelligent temperature sensing layer installation:

[0124] Thermochromic ink (color-changing temperature 45-65℃) is selected. This ink changes color according to temperature changes, thus enabling real-time monitoring of cable temperature. The printing temperature is 23℃, humidity is 45%, and the ink is laid at 0.6m intervals, with a coating thickness of 18μm. Precise control of printing temperature, humidity, and coating thickness ensures the stable performance of the thermochromic ink and accurately reflects cable temperature changes.

[0125] 2. Reinforcing layer wrapping:

[0126] A mesh structure is woven from shape memory alloy wires (shape recovery temperature 75°C) and spirally wrapped around the outside of the flexible buffer isolation layer with a 25% overlap rate.

[0127] Shape memory alloy wires will return to their original shape when the temperature reaches the shape recovery temperature. When the cable is deformed by external force, the shape memory alloy wires can restore the shape of the cable to a certain extent, thereby improving the cable's resistance to deformation.

[0128] 3. Grounding unit settings:

[0129] Using a copper conductor as the grounding conductor is advantageous because copper's excellent conductivity allows it to promptly conduct leakage current from the cable to the ground, ensuring the safety of personnel and equipment. A 1.2mm thick polyethylene insulating and waterproof layer is extruded and then welded to the grounding terminal. This insulating and waterproof layer prevents the grounding conductor from becoming damp and rusting, which would affect its grounding performance.

[0130] 4. Extrusion of inner and outer protective layers:

[0131] Using polyvinyl chloride material, the temperature of each zone of the twin-screw extruder is 145℃, 165℃, 180℃, 190℃, and 200℃. First, a 1.8mm inner protective layer is extruded, and then a 2.2mm outer protective layer is extruded. The speed is 15m / min, and the extruder is cooled in a 23℃ water bath.

[0132] Polyvinyl chloride (PVC) has good corrosion resistance and mechanical properties. The inner and outer sheaths can protect the internal structure of the cable from external environmental erosion, thus improving the cable's service life.

[0133] Through the above implementation steps, a reinforced cross-linked polyethylene cable was successfully fabricated. The hollow structure of the cable's central conductor, combined with an expansion heat dissipation reinforcement layer and a phase change heat dissipation layer, resulted in a conductor temperature reduction of approximately 20-30°C compared to traditional cables during high-load operation testing. This effectively reduced resistance loss due to heat generation and improved conductivity. The flexible buffer insulation layer effectively alleviated stress and protected the internal structure during simulated bending, tension, and vibration tests. The shielding layer provided significant shielding against electromagnetic interference across different frequency bands, ensuring stable signal transmission within the cable even in complex electromagnetic environments. The intelligent temperature-sensing layer accurately responded to temperature changes, exhibiting clear color changes and precise positioning. Overall, this cable demonstrates excellent performance in heat dissipation, mechanical properties, electromagnetic shielding, and temperature monitoring, making it suitable for a variety of complex applications.

[0134] Example 2:

[0135] I. Preparation of the central conductor:

[0136] 1. Material preparation:

[0137] A copper-magnesium alloy rod with a purity of 99.9% is selected as the center conductor material. While maintaining the good conductivity of copper, the copper-magnesium alloy increases the strength and hardness of the alloy, thereby improving the mechanical properties of the cable.

[0138] Expanded graphite particles have a diameter of 70-90 μm, while nanofiber particles have a diameter of 100-180 nm and a length of 3-5 μm. Expanded graphite particles and nanofiber particles of different sizes can cooperate to form a more complex heat conduction network, thereby improving heat dissipation performance.

[0139] 2. Particle pretreatment:

[0140] Expanded graphite particles were baked in a 350℃ high-temperature furnace for 1 hour. Higher baking temperatures allow for a more thorough removal of impurities and moisture from the surface of the expanded graphite particles. During plasma treatment, argon and oxygen (volume ratio 3:2) were introduced, and the treatment was carried out at 120Pa pressure for 10 minutes. Adjusting the gas ratio and pressure can alter the effect of plasma treatment, resulting in the formation of more active groups on the surface of the expanded graphite particles.

[0141] Nanofiber particles were reacted with 3.5 mol / L nitric acid solution at 70°C for 2 hours. Higher nitric acid concentrations and reaction temperatures resulted in the formation of more oxygen-containing functional groups on the surface of the nanofiber particles, enhancing their surface activity. The particles were then washed with water and dried before use.

[0142] 3. Center conductor processing:

[0143] The copper-magnesium alloy rod is machined into a hollow structure, with the hollow diameter being 1 / 5 of the outer diameter.

[0144] Expanded graphite particles and nanofiber particles were blended at a mass ratio of 7:3, with a filling rate of 88%. This higher filling rate further enhances the heat dissipation capacity of the expanded heat-dissipating reinforcement layer. Both ends were sealed after filling to prevent material leakage.

[0145] 4. Phase change heat dissipation layer setup:

[0146] Apply a 0.4 mm thick layer of phase change material (a blend of octadecane and polypropylene, mass ratio 6:4). Octadecane has a suitable phase change temperature and latent heat of phase change, while polypropylene enhances the stability and processability of the phase change material. Hot-press bonding ensures close contact between the phase change material and the central conductor, improving heat dissipation efficiency.

[0147] II. Extrusion of the central insulation layer:

[0148] 1. Preparation of insulation materials:

[0149] Cross-linked polyethylene insulation material has a density of 0.92 g / cm³ and a melt flow rate of 0.8 g / 10 min. Insulation materials with different densities and melt flow rates can be selected according to the specific needs of the cable to meet different electrical and mechanical performance requirements. Dry at 90℃ for 3 hours to remove moisture.

[0150] 2. Extrusion molding:

[0151] A single-screw extruder (screw diameter 140mm, L / D ratio 28:1) was used, with temperature settings of 125℃, 145℃, 165℃, 175℃, and 185℃. The larger screw diameter and L / D ratio improved the extruder's plasticizing capacity and extrusion stability. The center conductor was coated with insulating material at a speed of 12m / min and cooled in a 20℃ water bath. The slower extrusion speed and lower cooling temperature resulted in a denser insulating layer, improving insulation performance.

[0152] III. Fabrication of a flexible buffer isolation layer:

[0153] 1. Material preparation:

[0154] Silicone rubber is selected as the flexible rubber body, aerogel particles with a particle size of 30-50μm, and a two-component epoxy resin binder.

[0155] Silicone rubber has good high temperature resistance, low temperature resistance and insulation properties, and can adapt to different environmental conditions.

[0156] Two-component epoxy resin adhesives include:

[0157] 1. Component A: Bisphenol F type epoxy resin, which has low viscosity, good fluidity at room temperature, which is conducive to mixing with other materials, and has good chemical corrosion resistance and heat resistance after curing.

[0158] 2. Component B: Aliphatic amine curing agent (such as ethylenediamine). Aliphatic amine curing agents have high reactivity, enabling epoxy resin to cure rapidly, and the cured product has high strength. Components A and B are prepared at a mass ratio of 2.5:1.

[0159] 2. Adhesive preparation

[0160] Components A and B were stirred at 26°C for 9 minutes, and then stirred at 600 rpm for 15 minutes. Precise control of temperature, stirring time, and speed ensures stable performance of the binder.

[0161] 3. Mixing and wrapping:

[0162] The flexible rubber matrix is ​​plasticized for 8 minutes, then aerogel particles and binder are added and mixed for 18 minutes to ensure the aerogel particles are evenly dispersed within the flexible rubber matrix. It is then calendered into a 0.8mm sheet and wrapped with a 25% overlap. The thinner sheet and lower overlap allow for a more flexible buffer layer, improving the cable's flexibility.

[0163] IV. Constructing a shielding layer:

[0164] 1. Preparation of metal shielding mesh:

[0165] The electrolytic copper wire has a diameter of 0.08mm and a weaving density of 90%. The finer copper wire and higher weaving density improve the shielding effect and flexibility of the shielding mesh. The pre-stretching force is 40N for 12 minutes. Pre-stretching ensures the copper wires are more evenly aligned, increasing the tensile strength of the shielding mesh.

[0166] 2. Construction of the shielding layer:

[0167] The metal shielding mesh has a 110mm pitch and is wrapped with 0.08mm thick copper foil. It is then hot-pressed at 110℃ and 4MPa pressure for 12 minutes to firmly bond the copper foil to the metal shielding mesh. An extruded cross-linked polyethylene layer protects the shielding layer from external environmental influences.

[0168] V. Formation of the outer protective structure:

[0169] 1. Intelligent temperature sensing layer installation:

[0170] The thermochromic ink has a color-changing temperature of 55-75℃, a printing temperature of 24℃, and a humidity of 55%. It is laid at 1m intervals, with a coating thickness of 22μm. Different color-changing temperature ranges and printing conditions can be adjusted according to the cable's operating environment and monitoring requirements.

[0171] 2. Reinforcing layer wrapping:

[0172] The shape memory alloy wire (shape recovery temperature 85℃) is braided and wrapped with a 15% overlap. The higher shape recovery temperature and lower overlap can reduce the impact on the cable's flexibility while ensuring a certain degree of deformation resistance.

[0173] 3. Grounding Unit Setup

[0174] Aluminum conductors are used as grounding conductors because they are lightweight and low-cost. A 0.8mm thick polyethylene insulating and waterproof layer is extruded and connected to the grounding terminal.

[0175] 4. Extrusion of inner and outer protective layers:

[0176] Polyvinyl chloride (PVC) material, twin-screw extruder temperatures of 135℃, 155℃, 170℃, 180℃, and 190℃, inner sheath 1.2mm, outer sheath 1.8mm, speed 10m / min, cooled in a 21℃ water bath. Different extrusion temperatures, thicknesses, and speeds can be adjusted according to the specific requirements of the cable to meet different mechanical and protective performance requirements.

[0177] Following the process and material selection in this embodiment, the produced cable exhibits excellent overall performance. The copper-magnesium alloy material of the center conductor, combined with a special heat dissipation structure, allows the cable to operate normally even when the ambient temperature reaches 60°C, with minimal impact from its own heat generation on performance during high-temperature testing. The flexible buffer insulation layer and reinforcement layer work together to ensure that the shape memory alloy wires effectively recover some of their deformation when subjected to significant external forces, guaranteeing the cable's structural integrity. The shielding layer and grounding unit work together to effectively shield electromagnetic interference and ensure grounding safety in high-voltage electrical environments. The intelligent temperature-sensing layer responds rapidly to temperature changes under varying humidity conditions, demonstrating high stability. This cable exhibits excellent applicability in scenarios involving high temperatures, high mechanical stress, and complex electromagnetic environments.

[0178] Example 3:

[0179] I. Preparation of the central conductor:

[0180] 1. Material preparation:

[0181] The expansion graphite particles, with a purity of 99.92% and an oxygen-free copper rod, have a particle size of 50-70 μm, while the nanofiber particles have a diameter of 60-120 nm and a length of 1-3 μm. Particles of different sizes and diameters can form different microstructures, affecting the performance of the expansion heat dissipation enhancement layer.

[0182] 2. Particle pretreatment:

[0183] Expanded graphite particles were baked at 310℃ for 2 hours, then subjected to plasma treatment with argon and oxygen (volume ratio 5:1) at 105 Pa for 18 minutes. Nanofiber particles were reacted with 2 mol / L nitric acid solution at 60℃ for 3.5 hours, followed by washing and drying. The surface activity and properties of the particles can be optimized by adjusting the pretreatment conditions.

[0184] 3. Center conductor processing:

[0185] The oxygen-free copper rod is processed into a hollow structure with a hollow diameter of 1 / 3.5 of the outer diameter. Particles are blended at a mass ratio of 8:2, with a filling rate of 80%. Different mass ratios and filling rates can affect the heat dissipation performance and structural stability of the expansion heat dissipation reinforcement layer. Both ends are sealed after filling.

[0186] 4. Phase change heat dissipation layer setup:

[0187] Apply a 0.7 mm thick layer of phase change material (a blend of palmitic acid and polymethyl methacrylate, mass ratio 7:3). Palmitic acid has a suitable phase change temperature and latent heat, while polymethyl methacrylate enhances the stability and processability of the phase change material. Hot pressing is then used to bond the materials together, improving heat dissipation efficiency.

[0188] II. Extrusion of the central insulation layer:

[0189] 1. Preparation of insulation materials:

[0190] The cross-linked polyethylene insulation material has a density of 0.94 g / cm³ and a melt flow rate of 1.5 g / 10 min. It is dried at 82℃ for 4.5 hours to remove moisture.

[0191] 2. Extrusion molding:

[0192] A single-screw extruder (screw diameter 110mm, L / D ratio 24:1) was used, with temperatures of 132℃, 152℃, 172℃, 182℃, and 192℃. The center conductor was coated with insulating material at a speed of 20m / min and cooled in a 24℃ water bath. Different extruder parameters and process conditions can affect the quality and performance of the insulation layer.

[0193] III. Fabrication of a flexible buffer isolation layer:

[0194] 1. Material preparation:

[0195] Neoprene rubber is selected as the flexible rubber body, as it possesses excellent weather resistance, chemical corrosion resistance, and flame retardancy. Aerogel particles have a diameter of 10-30 μm, and a two-component epoxy resin binder is used.

[0196] 1. Component A: Phenolic epoxy resin, which has high heat resistance, chemical corrosion resistance and mechanical strength, and is suitable for applications with high performance requirements.

[0197] 2. Component B: Aromatic amine curing agent (such as m-phenylenediamine). Aromatic amine curing agents enable epoxy resin to have high heat resistance and hardness after curing. Components A and B are prepared at a mass ratio of 3.5:1.

[0198] 2. Adhesive preparation

[0199] Components A and B were stirred at 24°C for 12 minutes, and then stirred at 450 rpm for 25 minutes. Precise mixing conditions ensure the stability of the binder's performance.

[0200] 3. Mixing and wrapping:

[0201] The flexible rubber matrix is ​​plasticized for 15 minutes, then aerogel particles and binder are added and mixed for 25 minutes to ensure the aerogel particles are evenly dispersed within the flexible rubber matrix. It is then calendered into a 1.5mm sheet and wrapped with a 40% overlap. The thicker sheet and higher overlap improve the cushioning effect and thermal insulation performance of the flexible buffer layer.

[0202] IV. Constructing a shielding layer:

[0203] 1. Preparation of metal shielding mesh:

[0204] The electrolytic copper wire has a diameter of 0.15mm and a weaving density of 82%. The thicker copper wire and lower weaving density improve the mechanical strength of the shielding mesh. The pre-tensioning force is 70N for 6 minutes. Pre-tensioning ensures the copper wires are more evenly aligned, increasing the tensile strength of the shielding mesh.

[0205] 2. Construction of the shielding layer:

[0206] The metal shielding mesh has an 80mm pitch and is wrapped with 0.15mm thick nickel foil. It is then hot-pressed at 140℃ and 7MPa pressure for 6 minutes to firmly bond the nickel foil to the metal shielding mesh. An extruded cross-linked polyethylene layer protects the shielding layer from external environmental influences.

[0207] V. Formation of the outer protective structure:

[0208] 1. Intelligent temperature sensing layer installation:

[0209] The thermochromic ink has a color-changing temperature of 40-60℃, a printing temperature of 21℃, and a humidity of 42%. It is laid at 0.5m intervals, with a coating thickness of 16μm. Different color-changing temperature ranges, printing conditions, and laying intervals can be adjusted according to the cable's operating environment and monitoring requirements.

[0210] 2. Reinforcing layer wrapping:

[0211] The cable is woven with shape memory alloy wire (shape recovery temperature 70°C) with a 30% overlap. The lower shape recovery temperature and higher overlap improve the cable's resistance to deformation.

[0212] 3. Grounding unit settings:

[0213] A copper alloy conductor is used as the grounding conductor, as copper alloy conductors have good electrical conductivity and mechanical properties. A 1.5mm thick polyethylene insulating and waterproof layer is extruded and connected to the grounding terminal.

[0214] 4. Extrusion of inner and outer protective layers:

[0215] Polyvinyl chloride (PVC) material, twin-screw extruder temperatures of 142℃, 162℃, 178℃, 188℃, and 198℃, inner sheath 2mm, outer sheath 2.5mm, speed 18m / min, cooled in a 25℃ water bath. Different extrusion temperatures, thicknesses, and speeds can be adjusted according to the specific requirements of the cable to meet different mechanical and protective performance requirements.

[0216] The cable prepared in Example 3 exhibits excellent performance across various aspects. The special structure and filling material of the center conductor effectively suppress the skin effect in high-frequency power transmission simulation tests, significantly improving transmission efficiency. The aerogel particles and binder system of the flexible buffer layer enhance heat insulation and buffering performance; no damage was observed in the internal insulation layer during simulated impact experiments. The multi-layered structure of the shielding layer achieved a shielding effectiveness of over 95% in broadband electromagnetic interference tests. The excellent performance of the grounding unit ensures stable and reliable grounding of the cable in humid environments. The intelligent temperature-sensing layer facilitates real-time monitoring of cable temperature by maintenance personnel. This cable demonstrates significant advantages in special scenarios such as high-frequency power transmission, susceptibility to impact, and humidity.

[0217] As can be seen from these three embodiments, the reinforced cross-linked polyethylene cable of the present invention can achieve efficient heat dissipation, excellent mechanical properties, reliable electromagnetic shielding, accurate temperature monitoring, and good environmental adaptability under different material selections and process parameters, effectively meeting the needs of various complex application scenarios.

[0218] In summary, this invention constructs a highly efficient heat dissipation system by designing the central conductor as a hollow structure and filling it with an expanded heat dissipation reinforcement layer composed of a blend of expanded graphite particles and nanofiber particles, while simultaneously incorporating a phase change heat dissipation layer. The dense heat conduction channels formed by the interwoven expanded graphite particles and nanofiber particles can rapidly absorb the heat generated by the central conductor and conduct it radially to the conductor surface, accelerating heat dissipation. Moreover, the expanded heat dissipation reinforcement layer can automatically adjust according to the temperature changes of the central conductor. When the temperature rises, its volume expands, increasing the contact area with the central conductor and improving heat conduction efficiency. At the same time, it compresses the internal pores to reduce axial heat convection loss and can also absorb and store heat when the temperature rises rapidly, slowing down the rate of temperature increase. This unique heat dissipation and temperature regulation mechanism effectively prevents the central conductor from aging prematurely due to overheating, significantly extends the cable's service life, ensures stable operation of the cable in high-load power transmission and high-temperature environments, and greatly improves the cable's heat dissipation performance and temperature control capabilities.

[0219] This invention enhances the mechanical properties of the cable through multiple structural design improvements. The addition of nanofiber particles strengthens the overall strength and toughness of the expansion and heat dissipation reinforcement layer, effectively resisting external pressure and impact during cable laying and installation, thus protecting the central conductor. The expansion and heat dissipation reinforcement layer fills the central cavity of the central conductor, providing support and maintaining its shape stability, ensuring the cable's electrical performance. The flexible buffer layer consists of a flexible rubber body and internally filled aerogel particles. When the cable is subjected to external forces such as bending, stretching, or vibration, the flexible rubber body disperses stress through the cross-linking and stretching of molecular chains, while the aerogel particles also contribute to buffering and protecting the internal structure. Furthermore, the reinforcement layer woven from copper-based shape memory alloy wires, in conjunction with the flexible buffer layer, can recover the cable's shape to a certain extent when the cable is deformed by external forces. Leveraging the characteristics of the shape memory alloy wires, this significantly improves the cable's mechanical strength and resistance to deformation, enabling reliable operation even in space-constrained and externally susceptible environments.

[0220] The shielding layer of this invention adopts a double-layer structure of metal shielding mesh and metal foil. The metal shielding mesh is spirally wrapped around the outside of the central insulation layer, and the metal foil is on the outer layer. The two are fixed together by adhesive and thermoforming. Combined with an outer cross-linked polyethylene layer, this achieves effective shielding against broadband electromagnetic interference, providing comprehensive electromagnetic protection for the cable's internal insulation layer and conductor, ensuring stable operation of the cable in complex electromagnetic environments. Simultaneously, a grounding unit is set between the inner sheath and the shielding layer. The grounding conductor, as the core component, provides a low-impedance discharge path for fault current in the event of insulation failure or lightning strike, quickly diverting the current to the ground and preventing damage to other parts of the cable, thus reducing the safety risks caused by leakage. The insulating and waterproof layer covering the outside of the grounding conductor effectively blocks moisture intrusion, preventing the grounding conductor from becoming damp and corroded, ensuring long-term stable grounding performance. The grounding unit and the shielding layer work together to further enhance the electromagnetic shielding effect of the cable, ensuring the safety and reliability of the entire cable system.

[0221] This invention features intelligent temperature-sensing layers spaced along the outer sheath's extension direction, composed of a thermochromic ink coating surrounding the outer wall. When the cable experiences overload, partial short circuit, or other faults leading to temperature increases, the thermochromic ink coating responds promptly to temperature changes, issuing a warning signal through color alteration. The appropriate spacing (0.5m-1m) between adjacent thermochromic ink coatings, along with a coating thickness controlled between 15μm-25μm, ensures precise location of heat sources. This allows maintenance personnel to detect anomalies in the early stages of a fault, taking timely measures to prevent further escalation, effectively reducing maintenance costs and power outage risks, and significantly improving the safety and reliability of cable operation.

[0222] Wide Applicability and Environmental Adaptability: The unique cable structure design of this invention gives it wide applicability and strong environmental adaptability. In high-load power transmission scenarios, such as the main lines of urban power grids and large substations in industrial enterprises, the cable's efficient heat dissipation performance and self-regulating heat dissipation function ensure stable operation when transmitting large amounts of electrical energy, reducing the risk of failure due to overheating. In high-temperature environments, such as steel mills, glass factories, and boiler rooms, the expansion heat dissipation reinforcement layer and the overall heat dissipation structure effectively cope with external high temperatures, ensuring normal cable operation. In space-constrained scenarios, such as underground tunnels and building shafts, the cable's excellent mechanical properties and stable structural support reduce cable damage caused by external pressure, lowering maintenance costs. Furthermore, the materials used in each structural layer possess excellent weather resistance and corrosion resistance, enabling the cable to operate stably for extended periods in various natural and industrial environments, meeting the needs of diverse and complex application scenarios.

[0223] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. For those skilled in the art, any alternative improvements or transformations made to the implementation of the present invention fall within the protection scope of the present invention.

[0224] Any aspects of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A reinforced cross-linked polyethylene cable, characterized in that: It includes, from the inside out, a central conductor, a central insulating layer, a shielding layer, an inner protective layer, and an outer protective layer; the central conductor is hollow, and an expansion heat dissipation enhancement layer is filled in the central cavity of the central conductor; a phase change heat dissipation layer is disposed between the central conductor and the central insulating layer; a flexible buffer isolation layer is provided between the central insulating layer and the shielding layer, and the flexible buffer isolation layer is wrapped around the outer wall of the central insulating layer; The flexible buffer isolation layer includes a flexible rubber body, and a number of aerogel particles are filled and mixed inside the flexible rubber body. The aerogel particles are fixed to the flexible rubber body by an adhesive. The expanded heat dissipation enhancement layer is composed of a blend of expanded graphite particles and nanofiber particles; the expanded heat dissipation enhancement layer fills 80%-90% of the central cavity of the central conductor; The expanded graphite particles and nanofiber particles inside the central conductor intertwine to form a network, and work together with the expanded graphite to build a dense heat conduction channel; it can automatically adjust its heat dissipation performance according to the temperature change of the central conductor; it maintains a stable filling state at low temperatures; when the temperature rises, the internal structure expands rapidly to enhance heat dissipation capacity, realizing an intelligent self-regulating heat dissipation function. When the temperature of the central conductor rises, the volume of the expansion heat dissipation enhancement layer expands appropriately: on the one hand, it increases the contact area with the central conductor and improves the heat conduction efficiency; on the other hand, the pore structure inside the expansion heat dissipation enhancement layer is compressed, the gas flow is blocked, the axial heat convection loss is reduced, and the radial heat conduction is achieved for efficient heat dissipation, effectively preventing the conductor from aging due to overheating. When heat is transferred from the central insulation layer to the shielding layer, the aerogel particles form tiny heat-insulating units within the flexible rubber body. The heat must be reflected and scattered multiple times in the pores of the aerogel particles before it can continue to be transferred, thus effectively blocking the conduction of heat. Due to the uniform dispersion of the aerogel particles, a relatively stable temperature gradient is formed between the central insulation layer and the shielding layer, avoiding adverse effects on cable performance due to temperature fluctuations. When the central conductor is prepared, a guiding internal thread is made on its inner wall. When the conductor heats up and causes the heat dissipation strengthening layer material to expand, the internal thread can guide the material to expand uniformly in the radial and circumferential directions. A reinforcing layer is wrapped around the outside of the flexible buffer isolation layer. When the reinforced cross-linked polyethylene cable is deformed by external force, the reinforcing layer and the flexible buffer isolation layer work together to realize the cable's deformation recovery. The reinforcing layer includes a braided mesh structure wrapped around the central insulating layer, the braided mesh structure being woven from shape memory alloy wires.

2. The reinforced cross-linked polyethylene cable according to claim 1, characterized in that: Several intelligent temperature-sensing layers are provided at intervals along the extension direction of the outer protective layer. The intelligent temperature-sensing layer includes a thermochromic ink coating that surrounds the outer wall of the outer protective layer. The interval between adjacent thermochromic ink coatings is 0.5m-1m.

3. A reinforced cross-linked polyethylene cable according to claim 2, characterized in that: The thickness of the thermochromic ink coating is 15μm-25μm, and the material of the thermochromic ink coating is selected as wear-resistant thermochromic ink.

4. A reinforced cross-linked polyethylene cable according to claim 3, characterized in that: The shape memory alloy wire is drawn from a copper-based shape memory alloy.

5. A reinforced cross-linked polyethylene cable according to claim 4, characterized in that: The shielding layer includes a metal shielding mesh spirally wrapped around the outside of the central insulating layer, a metal foil wrapped around the outer layer of the metal shielding mesh, the metal foil and the metal shielding mesh being fixed together by adhesive and hot pressing, and a cross-linked polyethylene layer wrapped around the outside of the metal foil.

6. A reinforced cross-linked polyethylene cable according to claim 5, characterized in that: A grounding unit is provided between the inner protective layer and the shielding layer. The grounding unit includes a grounding conductor, and an insulating and waterproof layer is formed on the outside of the grounding conductor.

7. A method for producing a reinforced cross-linked polyethylene cable by extrusion molding, wherein the reinforced cross-linked polyethylene cable is the reinforced cross-linked polyethylene cable as described in any one of claims 1-6, characterized in that, Includes the following steps: Preparation of the central conductor: The conductor material is processed into a hollow structure, and an expansion heat dissipation strengthening layer is filled in the central cavity of the central conductor. The expansion heat dissipation strengthening layer is composed of a blend of expanded graphite particles and nanofiber particles, and the filling rate is controlled at 80%-90%. A phase change heat dissipation layer is set between the central conductor and the central insulating layer to be prepared later. Extruded central insulation layer: Using an extrusion process, a central insulation layer is extruded on the outside of the central conductor after the expansion heat dissipation reinforcement layer and the phase change heat dissipation layer are set; Fabrication of a flexible buffer layer: After the flexible rubber body and aerogel particles are mixed evenly with an adhesive, a wrapping process is used to form a flexible buffer layer on the outside of the central insulation layer. Constructing the shielding layer: First, the metal shielding mesh is spirally wrapped around the outside of the central insulation layer, then metal foil is wrapped around the outer layer of the metal shielding mesh. The metal foil and the metal shielding mesh are fixed together by adhesive and hot pressing. Finally, a cross-linked polyethylene layer is extruded and coated on the outside of the metal foil. Forming the outer sheath structure: During the extrusion molding process of the outer sheath, a temperature-sensitive color-changing ink coating is applied around its outer wall at intervals of 0.5m-1m to form an intelligent temperature-sensing layer; On the inner side of the outer sheath, a reinforcing layer made of shape memory alloy wire is wrapped around the outside of the flexible buffer isolation layer; A grounding unit is set between the inner sheath and the shielding layer, and the grounding conductor is covered with an insulating and waterproof layer and then installed in place; Finally, the inner sheath and the outer sheath are extruded to complete the extrusion molding of the reinforced cross-linked polyethylene cable.

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