Cable and cable preparation method

Abstract

The invention relates to a cable and a cable preparation method, in the length direction of the cable, a protection layer coats a cable core; the cable core comprises a core wire and an inflatable foaming filling layer, and the inflatable foaming filling layer is configured to be pre-filled with fire extinguishing gas and release the fire extinguishing gas in a preset state; the core wire comprises a cable conductor and an insulation structure, and the insulation structure wraps the cable conductor in the length direction; the cable conductor comprises wires and inter-strand pressure buffering hollow pipes, at least one inter-strand pressure buffering hollow pipe is located between two adjacent wires, and the inter-strand pressure buffering hollow pipes are configured to generate elastic deformation in an extruded state and recover in an external force disappearing state. A certain isolation buffer structure is arranged in the cable conductor, and when the cable is twisted, the inter-strand pressure buffer hollow pipe is extruded to generate elastic deformation, so that the buffer energy absorption effect is realized, the mutual extrusion acting force between wires is reduced, the core wire and the wires are protected, and the anti-twisting characteristic of the cable is further improved.

Description

Technical Field

[0001] This application relates to the field of cables, and in particular to cables and methods for manufacturing cables. Background Technology

[0002] Offshore wind power, as a core area of ​​clean energy development, is showing a trend of large-scale and far-reaching development. The single-unit capacity of offshore wind turbines continues to increase. At the same time, the layout of offshore wind farms is gradually expanding from nearshore to deep sea, and the distance between the turbines and the shore has extended from the initial few kilometers to tens of kilometers. Against this backdrop, the safety and reliability of deep-sea wind turbines face extremely high challenges. If an offshore turbine experiences a fire or other emergency, it will take a lot of time for rescue forces to reach the site from land, and the rescue operation will be extremely difficult due to factors such as the marine environment and weather conditions. Therefore, the cables, as a key power transmission component of deep-sea wind turbines, must meet the stringent requirements under extreme operating conditions to provide core assurance for the safe and stable operation of the turbines.

[0003] The working conditions of traditional medium-voltage anti-torsion cables are described below.

[0004] 1. Anti-torsion cables are laid in a suspended state inside the wind turbine tower, typically for more than 10 meters. Throughout the cable's lifespan, the conductor must bear the weight of more than 10 meters of cable for 24 hours.

[0005] 2. As the voltage level of the cable increases, the insulation thickness increases exponentially, and the weight of the cable also increases several times over. All the weight of the cable is applied to the copper conductor, which needs to withstand a higher load.

[0006] 3. Torsion-resistant cables with an electrical rating of 6kV or higher up to 35kV. The cable specifications for a three-phase system are generally 3×70, 3×95, 3×120, or larger.

[0007] 4. Wind turbine blades and nacelles need to withstand winds from different directions and will twist with the wind. Since the tower is fixed, the suspension cable section bears the electrical connection between the fixed tower and the twisting nacelle. This means the suspension cable section needs to twist back and forth around itself throughout its lifespan. Therefore, the suspension cable section needs to bear its own weight while constantly twisting around itself. This places higher demands on the cable insulation core's resistance to torsional deformation and the sheath's resistance to tearing and damage. With increasing voltage levels and cable outer diameter, the amount of flammable rubber and plastic per unit volume of the cable increases, posing a significant challenge to the cable's flame-retardant performance.

[0008] Therefore, the traditional design of anti-torsion cables for medium-pressure fans has the following drawbacks.

[0009] 1. Medium-voltage wind turbine anti-torsion power cables, using conventional soft copper conductors, are designed to withstand the constant yaw of wind turbines, causing the power transmission cable to twist around itself, and the conductor to twist frequently as well. Some designs add reinforcing elements to the conductor to increase its tensile strength; however, in actual use, more than 10% of the copper wires still break. Therefore, the design approach of using conventional soft copper conductors and adding reinforcing elements cannot meet the stringent requirements of long-term, frequent torsion.

[0010] 2. The copper conductor is designed with soft copper conductor and wrapped with insulating material. The copper conductor has a cylindrical structure. When it frequently twists around itself, there is not much space for adjacent copper strands inside the conductor to move relative to each other. They are squeezed together in a hard-on manner. The internal stress cannot be eliminated. Over time, the fatigue resistance of each strand of the conductor deteriorates, and strand breakage and wire breakage will occur, resulting in an extremely high risk of electrical failure.

[0011] 3. Medium-voltage insulated wires typically have three cores, with rubber strips filling the gaps between them. These rubber strips are usually designed in a fan shape and are quite dense, with a material density of 1.45 g / mm². 3 Although the filler has a certain degree of elasticity, it still restricts the relative displacement of the insulated core during cable torsion. The buffering effect is not obvious, which is not conducive to unloading the insulated core during torsion. Instead, it aggravates the damage to the insulated core and ultimately causes the failure of electrical insulation performance.

[0012] 4. The specifications of 35kV medium-voltage anti-torsion cables are 3×70, 3×95, and 3×120, with sheath thicknesses of 6.2mm, 6.4mm, and 6.7mm respectively, and cable outer diameters of 97.1mm, 101.6mm, and 105.9mm. The rubber volume ratio in these cables is 96.2%, 95.6%, and 95.5% respectively. In contrast, low-voltage cables of the same specifications have rubber volume ratios of only 85.2%, 84.6%, and 83.7%. This design significantly increases the volume of combustible materials, resulting in poorer flame-retardant performance during combustion. In the event of a fire, this high proportion of combustible materials in anti-torsion wind turbine cables is a fatal flaw for deep-sea wind turbine units. Summary of the Invention

[0013] Therefore, it is necessary to provide a cable and a method for manufacturing the cable.

[0014] One embodiment of this application is a cable (100) comprising a cable core (200) and a protective layer (500).

[0015] Along the length direction (110) of the cable (100), the protective layer (500) covers the outside of the cable core (200);

[0016] The cable core (200) includes a core wire (300) and an inflatable foam filling layer (400), wherein the inflatable foam filling layer (400) is configured to be pre-filled with fire extinguishing gas and to release the fire extinguishing gas in a preset state;

[0017] The core wire (300) includes a cable conductor (310) and an insulation structure, wherein the insulation structure covers the cable conductor (310) in the length direction (110);

[0018] The cable conductor (310) includes a conductor (311) and a cross-strand pressure buffer hollow tube (313), at least one of the cross-strand pressure buffer hollow tubes (313) is located between two adjacent conductors (311), and the cross-strand pressure buffer hollow tube (313) is configured to undergo elastic deformation under compression and to recover when the external force is removed.

[0019] The aforementioned cable (100) utilizes a core (200) in conjunction with a protective layer (500). On one hand, the interstrand pressure buffer hollow tube (313) in the cable conductor (310) works in conjunction with the conductor (311) to create a certain isolation and buffer structure within the cable conductor (310). When the cable (100) twists, the interstrand pressure buffer hollow tube (313) is compressed and undergoes elastic deformation, achieving a buffering and energy absorption effect. This reduces the mutual compression force between the conductors (311) and protects the core wire (300) and its conductors (311), thereby improving the torsional resistance of the cable (100). On the other hand, the cable core (200) is designed with an inflatable foam filling layer (400), which allows the inflatable foam filling layer (400) to release fire extinguishing gas under preset conditions such as melting, burning, or breakage, blocking and isolating external oxygen. The flame retardant properties of the cable (100) are improved by removing the combustible material inside the cable and thus delaying or even preventing the combustion of the combustible material inside the cable. On the other hand, the gas-filled foam filling layer (400) provided in the cable core (200) reduces the mutual squeezing force between the core wires (300) and protects the core wires (300), further improving the torsional resistance of the cable (100). On the other hand, the design of the gas-filled foam filling layer (400) not only reduces the weight of the cable (100) but also reduces the volume ratio of combustible plastic in the cable (100), further improving the flame retardant properties of the cable (100) and reducing the weight of the cable (100), thereby improving the overall safety of the cable (100), making it suitable for harsh working conditions, reducing the workload of maintenance, and especially suitable for offshore wind power generation.

[0020] In some embodiments, along the length direction (110) of the cable (100), the core wire (300) and the inflatable foam filling layer (400) have a circular cross-section; or, the core wire (300) and the outer edge of the inflatable foam filling layer (400) lie on a circle.

[0021] In some embodiments, the inflatable foam filling layer (400) includes an inflatable foam filling wall (410) and a pre-filled gas foam body (420).

[0022] Along the length direction (110) of the cable (100), the inflatable foam filling wall (410) surrounds the pre-filled gas foam (420).

[0023] In some embodiments, the pre-filled gas foam (420) is pre-filled with carbon dioxide and / or nitrogen, with a pore diameter of 0.1 mm to 1 mm and a gas locking volume of not less than 8.0 cm. 3 / g.

[0024] In some embodiments, the cable conductor (310) further includes a fiber cord (312) located at the center of the cable conductor (310) in a cross-section along the length direction (110).

[0025] In some embodiments, the interstrand pressure buffer hollow tube (313) is centrally symmetrically arranged relative to the fiber rope (312) in the cross-section.

[0026] In some embodiments, the interstrand pressure buffer hollow tube (313) is continuously or intermittently arranged along the length direction (110) of the cable (100); or,

[0027] The outer diameter of the hollow tube (313) in the interstrand pressure buffer is 90% to 110% of the outer diameter of the conductor (311); or,

[0028] At least two of the aforementioned interstrand pressure buffer hollow tubes (313) are arranged as hollow tube strings, and the cable conductor (310) includes at least two of the aforementioned hollow tube strings, wherein each of the hollow tube strings is centrally symmetrically arranged in the cross-section along the length direction (110); or,

[0029] The conductor (311) includes a single conductor and a multi-strand strand formed by at least two conductors.

[0030] As an example, for the interstitial pressure buffer hollow tube (313) that is intermittently set, the intermittent position of the interstitial pressure buffer hollow tube (313) is empty or the intermittent position of the interstitial pressure buffer hollow tube (313) is provided with an inflatable foam filler.

[0031] As an example, the hollow tube (313) of the interstitial pressure buffer is a plastic tube or a semiconductor tube.

[0032] As an example, the inter-segment pressure buffer hollow tube (313) includes a hollow tube wall (314) and a force-buffered hollow tube partition (316) supporting the hollow tube wall (314), and the force-buffered hollow tube partition (316) forms at least two hollow tube air chambers (315) spaced apart from each other on the hollow tube wall (314).

[0033] In some embodiments, the number of core wires (300) is three, and the number of inflatable foam filling layers (400) is three; and along the length direction (110) of the cable (100), the three core wires (300) are arranged centrally symmetrically, and the three inflatable foam filling layers (400) are arranged centrally symmetrically; or,

[0034] The protective layer (500) includes a wrapping layer (510) and a sheath layer (520) arranged in sequence, wherein the wrapping layer (510) covers the outside of the cable core (200).

[0035] In some embodiments, the insulation structure includes a conductor shielding layer (320), an insulation layer (330), an insulation shielding layer (340), and a metal shielding layer (350) arranged in sequence, wherein the conductor shielding layer (320) covers the outside of the cable conductor (310);

[0036] The conductor shielding layer (320) and the insulating shielding layer (340) are semi-conductive rubber materials. The semi-conductive rubber materials use ethylene propylene rubber as the base material and conductive carbon black as the conductive carrier.

[0037] The insulating layer (330) comprises hard EPDM rubber or polyether polyurethane;

[0038] The metal shielding layer (350) includes a metal braided strip.

[0039] In some embodiments, a cable manufacturing method is provided for manufacturing the cable (100) described in any embodiment; the cable manufacturing method includes the steps of:

[0040] Conductor material drawing;

[0041] The drawn conductor material is bundled to obtain a wire (311).

[0042] A hollow tube for inter-strand pressure buffer is formed by extrusion (313).

[0043] The interstrand pressure buffer hollow tube (313) and the conductor (311) are twisted together to obtain the cable conductor (310).

[0044] The conductor shielding layer (320), the insulation layer (330) and the insulation shielding layer (340) are co-extruded with the cable conductor (310) to obtain a semi-finished core wire (300);

[0045] A metal shielding layer (350) is wrapped around the semi-finished product to obtain a core wire (300).

[0046] The core wire (300) and the air-filled foam filling layer (400) are co-extruded to obtain the cable core (200).

[0047] A protective layer (500) is wrapped around the cable core (200) to obtain a cable (100). Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the structure of one embodiment of the cable described in this application.

[0050] Figure 2 for Figure 1 The illustrated embodiment is a schematic cross-sectional view along its length.

[0051] Figure 3 for Figure 2 A schematic diagram of the core wire structure in the embodiment shown.

[0052] Figure 4 for Figure 3 A schematic diagram of the hollow tube structure of the interstitial pressure buffer in the embodiment shown.

[0053] Figure 5 for Figure 2 A schematic diagram of the structure of the inflatable foam filling layer in the embodiment shown.

[0054] Figure 6 This is a schematic flowchart of an embodiment of the cable manufacturing method described in this application.

[0055] Figure 7 This is a schematic flowchart of another embodiment of the cable manufacturing method described in this application.

[0056] Reference numerals: cable (100), cable core (200), core wire (300), inflatable foam filling layer (400), protective layer (500);

[0057] Length direction (110), cable conductor (310), wire (311), fiber rope (312), interstrand pressure buffer hollow tube (313), hollow tube wall (314), hollow tube air chamber (315), force buffer hollow tube partition (316), conductor shielding layer (320), insulation layer (330), insulation shielding layer (340), metal shielding layer (350), gas-filled foam filling wall (410), pre-filled gas foam (420), wrapping layer (510), sheath layer (520). Detailed Implementation

[0058] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0059] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application's specification are for illustrative purposes only and do not represent the only possible implementation.

[0060] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0061] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0062] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and or" as used in this application includes any and all combinations of one or more of the associated listed items.

[0063] In some specific application embodiments, taking the power transmission of deep-sea wind turbine generators as an example, the power transmission of deep-sea wind turbine generators mainly adopts anti-torsion medium-voltage cables. Traditional anti-torsion medium-voltage cables are usually 6kV to 35kV rubber-sheathed anti-torsion cables. The product design standard of traditional anti-torsion medium-voltage cables adopts GB / T 33606 Wind Power Generation Torsion-Resistant Flexible Cable. The conductor adopts the fifth type of soft copper conductor conforming to the national standard GB / T 3956. The insulation adopts medium-voltage ethylene propylene rubber insulation. Both the inner and outer shields adopt semi-conductive rubber material. There is no metal shielding structure design outside the insulation shield. The cable structure adopts a design structure of 3 main lines plus metal shielding. The sheath design is a single layer of rubber sheath or polyurethane elastomer, i.e., TPU material. Taking 35kV anti-torsion cable as an example, the cable specifications are generally 3×70, 3×95, and 3×120. The cable insulation thickness reaches 10.5mm, and the cable's approximate outer diameters are 97.1mm, 101.6mm, and 105.9mm, respectively. However, the conductor's outer diameter is approximately 11.6mm, 13.5mm, and 15.2mm. Therefore, the cable's outer diameter is approximately 8.4 times, 7.5 times, and 7.0 times the conductor's outer diameter, respectively. Traditional anti-torsion medium-voltage cables suffer from insufficient torsional resistance and lack flame-retardant properties.

[0064] To improve the torsional resistance and flame retardant properties of cables, in one embodiment of this application, a cable includes a cable core and a protective layer; the protective layer covers the cable core along the length of the cable; the cable core includes a core wire and an inflatable foam filling layer, the inflatable foam filling layer being pre-filled with fire extinguishing gas and releasing the fire extinguishing gas in a preset state; the core wire includes a cable conductor and an insulation structure, the insulation structure covering the cable conductor along the length of the cable; the cable conductor includes a conductor and an inter-strand pressure buffer hollow tube, at least one of the inter-strand pressure buffer hollow tubes being located between two adjacent conductors, the inter-strand pressure buffer hollow tube being configured to undergo elastic deformation under compression and recover when the external force is removed. The aforementioned cable, through the combination of the cable core and protective layer, utilizes two main features. Firstly, the inter-strand pressure-buffering hollow tubes within the cable conductor, working in conjunction with the conductors, create a certain degree of isolation and buffering structure within the cable conductor. When the cable twists, the inter-strand pressure-buffering hollow tubes undergo elastic deformation under pressure, achieving a buffering and energy-absorbing effect. This reduces the mutual compressive force between the conductors, protecting the core and its conductors, thereby improving the cable's torsional resistance. Secondly, the cable core is designed with an inflatable foam filling layer. This foam filling layer releases fire-extinguishing gases under preset conditions such as melting, burning, or damage, blocking and isolating external oxygen contact. The presence of combustible materials inside the cable helps to delay or even prevent the combustion of these materials, thus improving the cable's flame-retardant properties. Furthermore, the air-filled foam filling layer in the cable core reduces the mutual compression forces between the core wires, protecting them and further enhancing the cable's torsional resistance. Additionally, the air-filled foam filling layer design not only reduces the cable's weight but also decreases the volume percentage of combustible plastics within the cable, further improving its flame-retardant properties and overall safety, making it particularly suitable for offshore wind power generation.

[0065] In some embodiments, a cable (100) such as Figure 1 As shown, it includes a cable core (200) and a protective layer (500); along the length direction (110) of the cable (100), the protective layer (500) covers the cable core (200); combined with Figure 2The cable core (200) includes a core wire (300) and an inflatable foam filling layer (400), the inflatable foam filling layer (400) is configured to be pre-filled with fire extinguishing gas and to release the fire extinguishing gas in a preset state; the core wire (300) includes a cable conductor (310) and an insulation structure, the insulation structure covering the cable conductor (310) in the length direction (110); the cable conductor (310) includes a conductor (311) and an interstrand pressure buffer hollow tube (313), at least one of the interstrand pressure buffer hollow tubes (313) is located between two adjacent conductors (311), the interstrand pressure buffer hollow tube (313) is configured to undergo elastic deformation under compression and recover when the external force disappears.

[0066] This design, through the cooperation of the cable core (200) and the protective layer (500), on the one hand, the interstrand pressure buffer hollow tube (313) in the cable conductor (310) cooperates with the conductor (311) to give the cable conductor (310) a certain isolation and buffer structure. When the cable (100) is twisted, the interstrand pressure buffer hollow tube (313) is squeezed and undergoes elastic deformation, realizing the buffering and energy absorption effect, thereby reducing the mutual squeezing force between the conductors (311) and the conductors (311), protecting the core wire (300) and its conductors (311), and thus improving the torsional resistance of the cable (100); on the other hand, the cable core (200) is designed with an air-filled foam filling layer (400), so that the air-filled foam filling layer (400) releases fire extinguishing gas in preset states such as melting, burning or breaking, blocking and isolating external oxygen from contacting the electric current. The internal combustible material of the cable helps to delay or even prevent the combustion of combustible materials inside the cable, thereby improving the flame retardant properties of the cable (100); on the other hand, since the cable core (200) is equipped with an air-filled foam filling layer (400), the mutual squeezing force between the core wires (300) is reduced, protecting the core wires (300) and further improving the torsional resistance of the cable (100); on the other hand, the design of the air-filled foam filling layer (400) not only reduces the weight of the cable (100), but also reduces the volume ratio of combustible plastics in the cable (100), further improving the flame retardant properties of the cable (100), and also reducing the weight of the cable (100), thereby improving the overall safety of the cable (100), making it suitable for harsh working conditions, reducing the workload of maintenance, and especially suitable for offshore wind power generation.

[0067] In each embodiment, such as Figure 1 As shown, along the length direction (110) of the cable (100), the protective layer (500) covers the outside of the cable core (200); in some embodiments, such as Figure 2As shown, the protective layer (500) includes a wrapping layer (510) and a sheath layer (520) arranged in sequence, wherein the wrapping layer (510) covers the cable core (200). This design, on the one hand, tightly wraps the cable core (200) with the wrapping layer (510), providing solid protection for the internal core wires (300) and the air-filled foam filling layer (400), reducing the impact of external impacts on the cable core (200) and protecting the integrity of the core structure; on the other hand, the sequentially arranged wrapping layer (510) and sheath layer (520) form a double protection, improving the wear resistance and corrosion resistance of the protective layer (500) and adapting to harsh working conditions. Meanwhile, the wrapping effect of the wrapping layer (510) enhances the structural integrity of the cable (100) in the length direction (110), and in conjunction with the anti-torsion design of the cable core (200), further optimizes the stability of the cable (100), reduces the maintenance frequency in scenarios such as offshore wind power generation, and improves the overall safety and reliability of power systems such as wind power systems.

[0068] In each embodiment, such as Figure 2 As shown, the cable core (200) includes a core wire (300) and an inflatable foam filling layer (400); and the inflatable foam filling layer (400) is configured to be pre-filled with fire extinguishing gas and to release the fire extinguishing gas in a preset state; as an example, the preset state includes a molten state, a burning state, and a damaged state. As an example, the fire extinguishing gas includes a non-flammable and non-combustible gas, including carbon dioxide, nitrogen, and rare gases, also known as inert gases, including helium, neon, argon, krypton, and xenon.

[0069] This design has several advantages. First, the gas-filled foam filling layer (400) between the core wires (300) of the cable core (200) reduces the weight of the cable (100) and significantly reduces the overall weight of the cable (100) borne by the core wires (300), which is beneficial to improving the overall torsional resistance (100) of the cable (100). Second, the gas-filled foam filling layer (400) is pre-filled with non-flammable and non-combustible extinguishing gases such as carbon dioxide, nitrogen, and helium. These gases are released in a timely manner under preset conditions such as melting, burning, or breakage, and can quickly fill the internal space of the cable (100), blocking the contact between external oxygen and the combustible materials inside the cable core (200). This inhibits the spread of fire from the source of combustion, effectively delaying or even terminating the combustion reaction, and significantly improving the flame-retardant reliability of the cable (100). Third, the gas-filled foam filling layer (400) fills between the core wires (300) to form a flexible buffer structure. When the cable (100) is subjected to external forces such as torsion or compression, it can disperse the flammability of the cable (100). The interaction force between the core wires (300) prevents damage to the core wires (300) and insulation structure. The interstrand pressure buffer hollow tube (313) further enhances the anti-torsion characteristics. On the other hand, the gas-filled foam structure greatly reduces the overall weight of the cable (100) and reduces the amount of flammable plastics used, which reduces the difficulty of transportation and installation and reduces the risk of combustion. At the same time, the chemical stability of the inert gas can prevent it from reacting with the internal components of the cable, protecting the core wires (300) and cable conductors (310) and ensuring stable performance. It is especially suitable for harsh working conditions with high maintenance difficulty, such as offshore wind power generation, improving safety and service life and reducing maintenance costs.

[0070] In some embodiments, combined Figure 3 Along the length direction (110) of the cable (100), the core wire (300) and the inflatable foam filling layer (400) have a circular cross-section; or, in some embodiments, the outer edges of the core wire (300) and the inflatable foam filling layer (400) lie on a circle. As an example, along the cross-section in the length direction (110), at least two core wires (300) are centrally symmetrically distributed, and at least two inflatable foam filling layers (400) are centrally symmetrically distributed, with one inflatable foam filling layer (400) between adjacent core wires (300) and one core wire (300) between adjacent inflatable foam filling layers (400). In some embodiments, such as... Figure 2 As shown, there are three core wires (300) and three inflatable foam filling layers (400); and along the length direction (110) of the cable (100), the three core wires (300) are arranged in a centrally symmetrical manner, and the three inflatable foam filling layers (400) are arranged in a centrally symmetrical manner.

[0071] This design, on the one hand, ensures that the core wire (300) and the inflatable foam filling layer (400) have a circular cross-section or a circular outer edge, making the cable core (200) structure uniformly distributed. When under stress, the pressure can be evenly transmitted along the circumferential direction, avoiding local stress concentration. Combined with the interstrand pressure buffer hollow tube (313), it further enhances the cable (100)'s resistance to torsion and compression, protecting the core wire (300) and cable conductor (310) from damage. On the other hand, it makes the cable core (200) form a circular structure, allowing the protective layer (500) to fit tightly against the cable core (200), reducing internal gaps and lowering the risk of external moisture and impurities intruding. At the same time, it improves the overall structural stability of the cable (100), preventing displacement and deformation during use. Furthermore, the uniform circular structure optimizes the bending performance of the cable (100), making it easier to lay and install. It also allows the extinguishing gas to diffuse evenly when released, quickly covering the combustible area, enhancing the flame retardant effect, adapting to harsh working conditions such as offshore wind power generation, improving reliability, and reducing maintenance costs.

[0072] In some of these embodiments, such as Figure 5 As shown, the inflatable foam filling layer (400) includes an inflatable foam filling wall (410) and a pre-filled gas foam body (420); along the length direction (110) of the cable (100), the inflatable foam filling wall (410) surrounds the pre-filled gas foam body (420). In some embodiments, the pre-filled gas foam body (420) is pre-filled with carbon dioxide and / or nitrogen, with a pore diameter of 0.1 mm to 1 mm and a gas locking volume of not less than 8.0 cm. 3 / g.

[0073] This design, with the pre-filled gas foam (420) as a closed-cell structure and the interstrand pressure buffer hollow tube (313) as an elastic matrix, combined with the pre-filled carbon dioxide and / or nitrogen and other flame-retardant gases, achieves high elastic recovery, high efficiency flame retardancy and excellent buffer energy absorption performance. It solves the problem that the cable (100) can achieve buffer energy absorption through the mutual compression of the three core wires (300) during the torsion process, greatly improving the anti-torsion performance. On the other hand, the carbon dioxide and / or nitrogen filled with a certain pressure in the foam filling is a flame-retardant gas. When the cable is burning, the carbon dioxide and / or nitrogen in the filling is released, blocking and isolating the contact between external oxygen and the combustible material inside the cable (100), preventing and delaying the combustion of the material, so that the cable has higher flame-retardant characteristics than traditional cables. Furthermore, the foam filling design not only reduces the weight of the cable, but also reduces the volume ratio of combustible rubber or plastic in the cable, further improving the flame-retardant characteristics of the cable (100). On the other hand, such innovative technical means take into account that the internal components of the cable (100) have greater displacement and higher resilience, the pressure between core wires (300) and between conductors (311) has greater buffering capacity, the combustibles inside the cable are reduced to the greatest extent, and the continuous release of non-combustible gases carbon dioxide and / or nitrogen during the combustion process also prevents external oxygen from participating in the combustion process of the internal materials of the cable, thereby improving the torsional resistance and flame retardant performance of the cable as much as possible, and enabling the cable (100) to have higher performance torsional resistance and high flame retardant performance.

[0074] In each embodiment, such as Figure 2 As shown, the core wire (300) includes a cable conductor (310) and an insulation structure. In the length direction (110), the insulation structure covers the cable conductor (310). In some embodiments, the insulation structure includes a conductor shielding layer (320), an insulation layer (330), an insulation shielding layer (340), and a metal shielding layer (350) arranged in sequence. The conductor shielding layer (320) covers the cable conductor (310). In some embodiments, the conductor shielding layer (320) and the insulation shielding layer (340) are semi-conductive rubber materials. The semi-conductive rubber materials use ethylene propylene rubber as the base material and conductive carbon black as the conductive carrier. The insulation layer (330) includes hard EPDM rubber or polyether polyurethane. The metal shielding layer (350) includes metal braided tape.

[0075] This design, on the one hand, involves the conductor shielding layer (320), insulation layer (330), insulation shielding layer (340), and metal shielding layer (350) sequentially covering the cable conductor (310) to form a multi-layered protective structure. The ethylene propylene rubber substrate combined with the semi-conductive rubber material with conductive carbon black allows the conductor shielding layer (320) and insulation shielding layer (340) to have a uniform electric field and eliminate partial discharge, thus preventing damage to the cable conductor (310) and insulation layer (330) and ensuring the conductivity stability of the core wire (300). On the other hand, the insulation layer (330) made of hard EPDM rubber or polyether polyurethane has excellent insulation performance and resistance to aging and high and low temperatures, which can effectively block current leakage, adapt to the insulation requirements under harsh working conditions, and extend the service life of the core wire (300). On the other hand, the metal shielding layer (350) made of metal braided tape can not only shield external electromagnetic interference and prevent the signal transmission of the cable (100) from being affected, but also enhance the mechanical protection capability of the core wire (300). Together with the air-filled foam filling layer (400) of the cable core (200) and the protective layer (500) of the cable (100), the overall structural strength is further improved. The synergistic effect of multiple structures not only strengthens the electrical performance and anti-interference capability of the cable (100), but also ensures the safety of the cable (100) in use.

[0076] In each embodiment, such as Figure 3 As shown, the cable conductor (310) includes a wire (311) and an interstrand pressure buffer hollow tube (313), at least one of the interstrand pressure buffer hollow tubes (313) being located between two adjacent wires (311). The interstrand pressure buffer hollow tube (313) is configured to undergo elastic deformation under compression and to recover when the external force is removed. In some embodiments, the wire (311) includes a single conductor and a multi-strand strand formed by at least two conductors. A single conductor is a single conductor, and a multi-strand strand is multiple conductors twisted together. In some embodiments, the wire (311) is a single conductor, or the wire (311) is a multi-strand strand formed by at least two conductors. As an example, Figure 3 In the embodiment shown, the conductor (311) is a multi-stranded wire formed by seven conductors.

[0077] This design, by setting up inter-strand pressure buffer hollow tubes (313) for the conductors (311) of the cable conductor (310), such as stranded wires, ensures that there is a certain degree of isolation and buffer between the strands of the conductors (311), such as stranded wires. On the one hand, during the cable twisting process, the strands of each layer of conductors (311) inside the core wire (300) will also twist in the same direction. When twisted to the limit position, the adjacent strands will generate mutual squeezing force. Due to the provision of a certain conductive pad and buffer by the inter-strand pressure buffer hollow tubes (313), the inter-strand pressure buffer hollow tubes (313) will be compressed to a certain extent, and there is no problem of hard contact between strands. This minimizes the compression and mutual mechanical force between adjacent strands, which is very beneficial to the torsion characteristics of the cable. On the other hand, since the hollow tubes between the strands can be made of elastic deformation materials such as rubber-based EVA, they exhibit good elasticity when the cable is twisted to its original state. The hollow tubes between the strands can return to their original shape, and the internal stress between the strands can be eliminated. If the cable continues to twist in the opposite direction, the force between the strands remains the same as when the cable reaches its limit position, preventing a direct contact. Therefore, direct force between the strands is avoided during cable twisting, and a certain degree of elastic displacement is allowed, minimizing conductor fatigue and improving the cable's torsional resistance.

[0078] In some embodiments, the interstrand pressure buffer hollow tube (313) is continuously arranged along the length direction (110) of the cable (100). Alternatively, the interstrand pressure buffer hollow tube (313) is intermittently arranged along the length direction (110) of the cable (100); as an example, for the intermittently arranged interstrand pressure buffer hollow tube (313), the intermittent position of the interstrand pressure buffer hollow tube (313) is empty or an air-filled foam filler is provided at the intermittent position of the interstrand pressure buffer hollow tube (313). As an example, the material of the air-filled foam filler is the same as that of the air-filled foam filling layer (400).

[0079] This design has several advantages. First, when the inter-strand pressure buffer hollow tube (313) is continuously installed along the length direction (110) of the cable (100), it can provide a full-length and uniform isolation buffer for the inside of the cable conductor (310). When the cable (100) is twisted or squeezed, the force between the conductors (311) can be dispersed throughout the entire length, avoiding local force concentration that could damage the conductors (311) and continuously ensuring the integrity of the core wire (300). Second, the intermittent installation method can flexibly adapt to different working conditions. The empty intermittent position can further reduce the weight of the cable (100), and the inflatable foam filler with the same material as the inflatable foam filler layer (400) can not only continue the buffer protection effect, but also take into account the weight reduction effect and flame retardant properties. On the other hand, both of the above-mentioned configuration methods can be combined with the air-filled foam filling layer (400) of the cable core (200) to double strengthen the torsion and compression resistance of the cable (100) without affecting the fire extinguishing gas release effect. This ensures the conductivity stability of the cable conductor (310) and improves the overall structural adaptability, making the cable (100) more reliable under harsh working conditions, thereby effectively reducing maintenance costs and frequency.

[0080] The thickness of the inter-strand pressure buffer hollow tube (313) can be the same as or different from that of the wire (311). In some embodiments, the outer diameter of the inter-strand pressure buffer hollow tube (313) is 90% to 110% of the outer diameter of the wire (311). As an example, the inter-strand pressure buffer hollow tube (313) is a plastic tube or a semiconductor tube, wherein the semiconductor tube is conductive and the conductivity of the semiconductor tube is weaker than that of the wire (311).

[0081] This design, on the one hand, allows the interstrand pressure buffer hollow tube (313) to form a suitable arrangement structure with the conductor (311), ensuring balanced internal force on the cable conductor (310), uniform elastic deformation during compression, and more stable buffer energy absorption effect, effectively reducing the interaction force between the conductors (311); on the other hand, the choice of material for plastic tubes or semiconductor tubes is flexible to adapt to different needs. Semiconductor tubes have both weak conductivity and do not affect the main conductivity of the conductor (311), ensuring both conductivity stability and maintaining the buffering effect. Furthermore, the two thickness matching methods and the two types of tubes can be combined with the air-filled foam filling layer (400) of the cable core (200) to further enhance the torsional resistance of the cable (100) without adding extra structural burden.

[0082] In some of these embodiments, such as Figure 3As shown, at least two of the interstrand pressure buffer hollow tubes (313) are arranged in a hollow tube string, and the cable conductor (310) includes at least two of the hollow tube strings. In the cross-section along the length direction (110), each of the hollow tube strings is centrally symmetrically arranged. For example, in the cross-section along the length direction (110), the axes of each of the interstrand pressure buffer hollow tubes (313) in the hollow tube strings are located on the same straight line. For example, Figure 3 In the illustrated embodiment, the cable conductor (310) includes three hollow tube strings, and adjacent two hollow tube strings form a 120-degree angle in the cross-section along the length direction (110). As an example, in each strand of the conductor (311), such as a conductor strand, the inter-strand pressure buffer hollow tubes (313) are symmetrically arranged at a certain angle, and the number of hollow tube strings provided in each cable conductor (310) is 3, and the angle between two adjacent hollow tube strings based on the center of the cable conductor (310) is 120 degrees. As an example, the core wire (300) is symmetrically arranged with 3 hollow tube strings, and each hollow tube string is provided with at least two, for example, three, inter-strand pressure buffer hollow tubes (313). The inter-strand pressure buffer hollow tubes (313) in each hollow tube string can be closely adjacent vertically or not adjacent; the inter-strand pressure buffer hollow tubes (313) in different core wires (300) can be closely adjacent vertically or not adjacent.

[0083] This design, on the one hand, arranges at least two of the interstrand pressure buffer hollow tubes (313) into hollow tube strings, and at least two of the hollow tube strings of the cable conductor (310) are centrally symmetrically arranged in the cross section of the length direction (110), so that the internal buffer structure of the cable conductor (310) is evenly distributed. When under stress, it can simultaneously disperse the squeezing force between the conductors (311) from multiple symmetrical directions, avoiding local stress concentration. Combined with the elastic deformation characteristics of the interstrand pressure buffer hollow tubes (313), it greatly improves the torsion resistance and compression resistance of the cable (100), effectively protecting the integrity of the conductors (311) and the core wires (300). On the other hand, the design of the three hollow tube strings symmetrically distributed at a 120-degree angle further optimizes the force transmission path. When the cable (100) is twisted, each hollow tube string deforms and absorbs energy in synergy, and the buffering effect is more stable and efficient. On the other hand, each strand of the conductor (311) is symmetrically equipped with inter-strand pressure buffer hollow tubes (313) at an angle, so that the buffer protection covers the entire structure of the cable conductor (310). Combined with the air-filled foam filling layer (400) of the cable core (200), the anti-torsion characteristics are doubly enhanced. At the same time, the symmetrical structure ensures that the conductivity of the cable conductor (310) is uniform, avoids the impact of structural deviation on transmission stability, effectively reduces the risk of damage to the conductor (311) and reduces the frequency of maintenance of the conductor (311), and improves the overall safety, reliability and service life of the cable (100).

[0084] To improve the torsional resistance of the hollow tube (313) in the interstitial pressure buffer, as an example, such as Figure 4 As shown, the inter-strand pressure buffer hollow tube (313) includes a hollow tube wall (314) and a force-buffering hollow tube partition (316) supporting the hollow tube wall (314). The force-buffering hollow tube partition (316) forms at least two mutually spaced hollow tube air chambers (315) on the hollow tube wall (314). With this design, on the one hand, the hollow tube wall (314) of the inter-strand pressure buffer hollow tube (313) is combined with the force-buffering hollow tube partition (316) to form at least two mutually spaced hollow tube air chambers (315), which simultaneously improves the structural strength and elastic deformation capacity. When the cable (100) twists, the air chambers can distribute the force and absorb energy in a coordinated manner, avoiding excessive local deformation or damage of the hollow tube, and significantly enhancing the torsional durability. On the other hand, the multi-chamber structure makes the buffering and energy absorption more balanced, which can more effectively reduce the mutual compression between conductors (311). Combined with the air-filled foam filling layer (400) of the cable core (200), the torsional resistance of the cable (100) is double-strengthened. Furthermore, the compartmentalized air chamber design ensures the structural stability of the inter-strand pressure buffer hollow tube (313). Even if a single air chamber is damaged, the remaining air chambers can still maintain the buffering function, thereby effectively improving the operational reliability of the cable conductor (310).

[0085] To improve the tensile strength of the core wire (300) and its cable conductor (310), in some embodiments, such as Figure 3As shown, the cable conductor (310) also includes a fiber rope (312), which is located at the center of the cable conductor (310) in the cross-section along the length direction (110). In some embodiments, the inter-strand pressure buffer hollow tube (313) is centrally symmetrically arranged with respect to the fiber rope (312) in the cross-section. As an example, the fiber rope (312) is ultra-high molecular weight polyethylene fiber, or UHMWPE for short. Ultra-high molecular weight polyethylene fiber is made of ultra-high molecular weight polyethylene with a molecular weight between 1 million and 5 million, and has advantages such as wear resistance, impact resistance and high toughness. With this design, on the one hand, the addition of ultra-high molecular weight polyethylene fiber as fiber rope (312) at the center of the cable conductor (310) greatly improves the overall tensile strength of the cable (100) and its cable conductor (310), and on the other hand, the fiber rope (312) has good flexibility and bending performance, which greatly helps to improve the bending and torsional performance of the cable (100). On the other hand, the fiber rope (312) located at the center of the cable conductor (310) is made of ultra-high molecular weight polyethylene (UHMWPE) with a molecular weight of 1 million to 5 million. Its excellent wear resistance, impact resistance and toughness greatly improve the tensile strength of the core wire (300) and the cable conductor (310), effectively resisting the damage of tensile external force to the cable (100). Furthermore, the interstrand pressure buffer hollow tube (313) is centrally symmetrically arranged relative to the fiber rope (312), so that the internal force of the cable conductor (310) is balanced. Combined with the buffer deformation capacity of the hollow tube, the anti-torsion and anti-compression effects are further optimized. On the other hand, the fiber rope (312) and the interstrand pressure buffer hollow tube (313) work together to strengthen the structural stability of the cable conductor (310) and ensure that the conductivity is not affected. It is suitable for various harsh working conditions, reduces the risk of failure caused by external force, reduces maintenance costs, and improves the overall service life and safety reliability of the cable (100).

[0086] In some specific application embodiments, the cable (100) may also be referred to as a high-torsion, high-flame-retardant wind power anti-torsion cable, in order to improve the torsional resistance of the cable conductor and the overall flame-retardant properties of the cable. In some embodiments, the cable (100) includes three power-insulated cores, three sets of air-filled foam fillers, and a protective layer (500) covering the surface of the cable core (200). The protective layer (500) includes a wrapping layer (510) and an outer sheath layer; wherein the power-insulated cores are used as core wires (300), the air-filled foam fillers are used as air-filled foam filler layers (400), and the outer sheath layer is also the sheath layer (520).

[0087] As an example, the power insulated core includes a cable conductor (310) and a conductor shielding layer (320), an insulation layer (330), an insulation shielding layer (340), and a metal shielding layer (350) covering the cable conductor (310). The cable conductor (310) includes a fiber rope (312) at the center, several layers of copper strands on the periphery, and a hollow tube (313) for interstrand pressure buffer between the strands of each stranded layer; wherein, the copper strands serve as the conductor (311), and the fiber rope (312) is the central organic fiber rope.

[0088] As an example, the central organic fiber rope is made of ultra-high molecular weight polyethylene fiber, which is beneficial to significantly improve the overall strength of the cable conductor (310). As an example, the outer layers of copper strands are made of multiple copper wires bundled together, i.e., copper strands, and the pitch ratio of the strands is generally controlled between 12 and 20 times. As an example, the inter-strand pressure buffer hollow tube (313) between the strands of each strand layer is a circular plastic hollow tube, the outer diameter of the hollow tube is basically the same as the diameter of the copper strand, the outer diameter is controlled between 2.0 mm and 4.0 mm, and the wall thickness of the pressure buffer hollow tube is controlled between 0.5 mm and 1.0 mm. The interior of the interstrand pressure buffer hollow tube (313) can be continuous along the entire length of the cable, i.e., a single complete tube; or it can be segmented, i.e., the interstrand pressure buffer hollow tube (313) contains segments of air spaced apart, with a force-buffered hollow tube partition (316) designed between adjacent air segments. The length of the air segments is set to 5mm to 200mm. This design, by setting an inflatable foam filling layer (400) between or next to the core wires (300) and an elastic semi-conductive interstrand pressure buffer hollow tube (313) between or next to the conductors (311), solves the problem of direct mechanical pressure and stress generated between conductors (311) during the torsion of the cable (100), and plays a decisive role in preventing conductors (311) from breaking during the torsion process.

[0089] As an example, the interstitial pressure buffer hollow tube (313) is made of semi-conductive EVA material with a Shore hardness of 78A to 95A. According to ISO868:2003, the Shore hardness of the material is D60±2, which has both structural support and extrusion deformation capability; the compression performance is: stress ≤8MPa under 20% compression deformation, and compression recovery rate ≥95%. According to GB / T 1041-2008, the test conditions for compression performance are: compression time 30s, recovery within 10s after release; according to ISO 527-1:2019, the elastic recovery is ≥94% after 100% tensile deformation to ensure shape stability after repeated compression; according to ASTM D1044-2016, the wear resistance under 10N load is: wear amount ≤0.08cm³ / 1.61km to adapt to long-term contact friction of wires (311), such as copper wire; the corrosion resistance is: after immersion in 120℃ environment for 1000h, there is no oxidation discoloration or leaching after contact with copper wire. This design increases the buffer distance by setting an interstrand pressure buffer hollow tube (313) between the conductors (311) of the cable conductor (310), for example, between the strands. Most of the torsional force and deformation on the conductor (311) are transferred to the buffer hollow tube, which greatly eliminates the pressure and torsional force on the conductor (311) and the conductor (311), and significantly increases the torsional resistance of the core wire (300) and its cable conductor (310).

[0090] As an example, the conductor shielding layer (320) and the insulating shielding layer (340) are rubber shielding materials, using ethylene propylene rubber as the base material and special conductive carbon black as the conductive carrier to obtain a semi-conductive rubber material. As an example, the semi-conductive rubber material, by weight, includes: 100 parts ethylene propylene rubber, 2 to 4 parts crosslinking agent, 16 to 20 parts plasticizer, 2 parts anti-aging agent, 20 to 30 parts conductive carbon black, 3 parts dispersing agent, and 6 to 10 parts graphite powder. The rubber is refined through a specific process to become the rubber shielding material. The resulting rubber has a volume resistivity of ≤100 Ω•m at 20°C, a volume resistivity of ≤500 Ω•m at 90°C, and a Shore A hardness of ≤80. In other embodiments, the semiconductive rubber material, by weight, comprises: 100 parts EPDM rubber, 2 to 4 parts crosslinking agent, 12 to 25 parts plasticizer, 2 parts anti-aging agent, 25 to 35 parts conductive carbon black, 4 parts dispersing agent, and 5 to 8 parts graphite powder. The rubber is also refined using a specific process to become the rubber shielding material. The resulting rubber has a volume resistivity of ≤100 Ω•m at 20°C, a volume resistivity of ≤500 Ω•m at 90°C, and a Shore A hardness of ≤70. This design allows the conductor shielding layer (320) and the insulating shielding layer (340) to have good processability and excellent insulation shielding performance, while maintaining stable conductivity at high temperatures, thus extending the service life of the cable (100).

[0091] As an example, the insulation layer (330) is made of hard grade ethylene propylene diene rubber (HEPR). The insulation layer (330) has the following characteristics: its thermo-oxidative aging performance reaches 168 hours at 135°C, with a tensile strength retention rate ≥80% and an elongation at break retention rate ≥75%; its corona aging resistance reaches ≥85% dielectric strength retention rate after 1000 hours of corona aging; its damp heat aging resistance is ≥85% at 70°C and 95%RH for 1000 hours, with a tensile strength retention rate ≥85% and a volume resistivity ≥1×10⁻⁶. 13 Ω•m. The insulation thickness is designed according to different voltage levels; for example, the thickness of the insulation layer (330) is 3.4 mm to 10.5 mm.

[0092] As an example, the metal shielding layer (350) is a metal braided layer woven outside the insulating shielding layer (340). As an example, the metal wire is a braided soft copper wire with a diameter of 0.15 mm to 0.30 mm, the number of braided layer spindles is 24 to 32, and the number of oxygen-free copper wire strands in each spindle is 6 to 12.

[0093] As an example, the cable core (200) includes three core wires (300) and three inflatable foam filling layers (400). As an example, a power-insulated core is used as the core wire (300), and an inflatable foam filler is used as the inflatable foam filling layer (400); that is, the cable core (200) is composed of 3 power-insulated cores and 3 sets of inflatable foam fillers, for example, 3 power-insulated cores and 3 sets of semi-conductive inflatable foam fillers are used to form a cable according to a certain direction and pitch ratio. In order to tighten the core wires (300) and the inflatable foam filling layers (400), the cable core (200) is wrapped with 1 to 2 layers of fiber cloth as a wrapping layer (510). The semi-conductive inflatable foam filler has a triangular shape. Through cabling, the 3 sets of semi-conductive inflatable foam fillers and the 3 power-insulated cores can form a regular circle. With this design, during the torsion process of the cable (100), the relative displacement and compressive force of the core wire (300) are transmitted to the elastic inflatable foam filling layer (400), which also maximizes the compressive strength resistance of the insulated core wire and prevents insulation damage during the torsion process. Therefore, the electrical insulation performance of the cable (100) is improved, and the torsion resistance of the cable (100) is also greatly improved.

[0094] As an example, the inflatable foam filler wall (410) is a uniform plastic layer with a thickness of 0.5 mm to 1 mm, and the interior of the plastic layer is a pre-filled gas foam (420) in an inflatable state. The inflatable foam filler layer (400) has good elasticity. The foam filler uses ethylene-vinyl acetate copolymer, i.e., EVA, as the matrix and constructs a closed-cell foam structure through supercritical fluid foaming technology. As an example, the thickness of the inflatable foam filling wall (410), i.e. the thickness of the outer perimeter of the foam filling, is precisely controlled to be 0.5 mm with a tolerance of ≤ ±0.03 mm. The closed-cell rate of the foam structure is ≥ 98%, the foaming rate is 85% to 90%, and the corresponding foaming degree, i.e. the foaming ratio, is 6.67 to 10 times. The foaming degree is defined as the ratio of the volume of the product after foaming to the volume of the EVA matrix material before foaming. The cells are uniformly spherically distributed, and the non-combustible gases such as CO2 or N2 are stably locked in the foam cavity. The cell diameter is 0.1 mm to 1 mm. The gas locking amount is ≥ 8.0 cm³ / g, and the gas retention rate after 12 months of storage at room temperature and pressure is ≥ 95%. This foaming degree parameter can balance elastic recovery and structural stability, ensuring that the product has both low stress buffering characteristics and high recovery rate under 20% compression deformation. This design involves injecting CO2 and / or N2 gas at a certain pressure into the inflatable foam filling. Since CO2 and N2 gases have no flammability, during the combustion process of the cable (100), the continuous release of CO2 and N2 gases prevents external oxygen from entering the cable (100), thus preventing and delaying the combustion of internal combustibles. For cables (100) with a high proportion of rubber or plastic volume, this significantly improves the flame retardant and non-combustible properties of the cable (100). Compared with traditional cables, the flame retardant performance of the cable (100) is greatly improved, achieving high flame retardant characteristics.

[0095] As an example, the protective layer (500) includes a wrapping layer (510) and a sheath layer (520). As an example, the wrapping layer (510) is one, two, or several layers of wrapping tape wrapped around the cable core (200), tightly bound in an overlapping manner. The material can be non-woven fabric or fiberglass tape with a thickness of 0.1 mm to 0.3 mm, and the overlap rate of the tape is controlled between 10% and 30%. As an example, the sheath layer (520), also called the outer sheath, is a layer of rubber or plastic extruded outside the outer wrapping layer of the cable core, with an extrusion thickness of 2.0 mm to 7.0 mm. As an example, the sheath layer (520) is made of rubber or an elastomer. As an example, the rubber material is chlorinated polyethylene, and the elastomer material is polyether-type polyurethane. The polyether-type polyurethane material is obtained by reacting polyether-type polyols with isocyanates. Because the ether bonds in the polyether polyol molecule have low cohesive energy and are easily rotated, the polyether-type polyurethane material obtained by reacting it with isocyanates possesses torsional resistance. As an example, the sheath layer (520) is made of low-temperature resistant, flame-retardant chlorinated polyethylene or polyurethane elastomer.

[0096] In some specific application embodiments, such as Figure 2 As shown, the cable core (200) includes three sets of core wires (300), three sets of inflatable foam filling layers (400) between the core wires (300), a wrapping layer (510) covering the cable core (200), and a sheath layer (520). Among them, the core wires (300) include, from the inside out, a cable conductor (310), a conductor shielding layer (320), an insulation layer (330), an insulation shielding layer (340), and a metal shielding layer (350). As an example, the cable conductor (310) includes a fiber rope (312), several layers of conductors (311) around the fiber rope (312), and a hollow tube (313) for interstrand pressure buffer in each layer of conductors (311), and they are twisted according to a certain twisting direction and twisting pitch ratio. As an example, the cable (100) or its core (200) adopts a uniform arrangement of 3 core wires (300) and 3 sets of air-filled foam filling layers (400), and the cable section diameter ratio adopts a design of 16 to 25 times to achieve overall structural stability of the cable (100).

[0097] To achieve high strength and torsional resistance, as an example, the fiber rope (312) is composed of multiple bundles of ultra-high molecular weight polyethylene (UHMWPE) fibers with a fiber count of 500D to 2000D. The specific strength of UHMWPE fiber is 15 times that of high-quality steel, its specific modulus is second only to special carbon fiber, and its tensile strength can reach over 3.6 GPa. Its impact resistance and abrasion resistance are also excellent; its energy absorption capacity is superior to aramid, its abrasion resistance is 4 times that of HDPE, and its density is only 0.97 g / cm³. 3 This is to improve the overall strength of the cable conductor (310).

[0098] To improve the compressive strength between the conductors (311) and strands in the cable conductor (310), thereby reducing conductor fatigue and minimizing conductor breakage, as an example, the interstrand pressure buffer hollow tube (313) is installed between the conductors (311) 11 of the cable conductor (310). During the torsion of the cable (100), it reduces the mutual friction and compression forces between the conductors (311) and the conductors (311) of the cable (100), achieving energy absorption and buffering effects. On each layer of conductors (311) of the conductor cable (310), the interstrand pressure buffer hollow tube (313) is symmetrically arranged at a certain angle. The number of hollow tube strings formed by the interstrand pressure buffer hollow tubes (313) in each layer of the cable conductor (310) is 3, and the included angle between adjacent hollow tube strings, i.e., the included angle with the center of the conductor, is 120°.

[0099] As an example, the inter-strand pressure buffer hollow tube (313) includes a hollow tube wall (314), a hollow tube air chamber (315), and a force-buffering hollow tube partition (316). Along the length direction (110) of the cable (100), there can be n hollow tube air chambers (315) and n force-buffering hollow tube partitions (316). In other embodiments, there can be one hollow tube wall (314) and one hollow tube air chamber (315), meaning that along the entire length of the cable (100), the inter-strand pressure buffer hollow tube (313) is entirely a hollow tube without partitions, without any intermediate force-buffering hollow tube partitions (316). As an example, the outer diameter of the inter-strand pressure buffer hollow tube (313) is controlled between 2.0 mm and 4.0 mm, and the wall thickness is controlled between 0.5 mm and 1.0 mm. When using the air section scheme, the length of the air section is set from 5mm to 200mm depending on the outer diameter of the hollow tube (313) in the inter-segment pressure buffer.

[0100] In some embodiments, a cable manufacturing method is provided for manufacturing the cable (100) described in any embodiment; such as Figure 6 As shown, the cable manufacturing method includes the following steps: drawing conductor material into wires; bundling the drawn conductor material to obtain a conductor; forming a hollow tube with interstrand pressure buffer by extrusion; twisting the hollow tube with interstrand pressure buffer and the conductor together to obtain a cable conductor; co-extruding the conductor shielding layer, the insulation layer, and the insulation shielding layer together with the cable conductor to obtain a semi-finished core wire; covering the semi-finished product with a metal shielding layer to obtain a core wire; co-extruding the core wire with an air-filled foam filling layer to obtain a cable core; and covering the cable core with a protective layer to obtain a cable. Before co-extruding the core wire with the air-filled foam filling layer, the cable manufacturing method further includes the step of providing an air-filled foam filling layer. It is understood that since the cable manufacturing method is used to manufacture the cable (100) of any embodiment, the cable manufacturing method also has the beneficial technical effects of the cable (100), which will not be elaborated here. In some embodiments, a cable manufacturing method is as follows: Figure 7 As shown, it includes the following steps: wire drawing, wire bundling, hollow tube extrusion, stranding, three-layer co-extrusion, metal shielding, gas filling extrusion, cabling, and sheathing.

[0101] To improve the overall torsional resistance and high flame retardant properties of the cable (100), as an example, the gas-filled foam filling layer (400) is fan-shaped or similar in shape. For example, three sets of fan-shaped gas-filled foam filling layers (400) are arranged between the three core wires (300). The gas-filled foam filling layer (400) includes a gas-filled foam filling wall (410) and a pre-filled gas foam body (420). The gas-filled foam filling wall (410) surrounds the pre-filled gas foam body (420) and forms an integral structure. The gas-filled foam filling layer (400) or its pre-filled gas foam body (420) can be filled with carbon dioxide or nitrogen at a certain pressure.

[0102] Taking medium- and high-voltage power cables as an example, the cable manufacturing method described herein is used to manufacture FDEH-26 / 35kV-3×95 cables; wherein, FDEH corresponds to a medium- and high-voltage cable structure of copper core + cross-linked polyethylene insulation + phase-separated shielding + weather-resistant outer sheath; 26 / 35kV corresponds to a long-term operating phase voltage ≤26kV and line voltage ≤35kV; 3×95 corresponds to a three-core cable with a nominal cross-sectional area of ​​95mm² per core. 2 The cable manufacturing method includes the following steps.

[0103] Wire drawing: The copper conductor uses T1 grade copper rod as raw material, and is drawn into wire using a continuous annealing large drawing machine. The single wire is drawn to TR-2.9mm using a continuous drawing and annealing method, then further drawn to TR-1.1mm using a medium drawing machine, and finally to TY-0.49mm using a fine drawing machine. TR-2.9mm corresponds to the soft state of pure copper with a diameter of 2.90mm, and TY-0.49mm corresponds to the hard state of pure copper with a diameter of 0.49mm.

[0104] Annealing: Annealing is carried out using a 40-head annealing machine. The annealing temperatures in zones 1 to 3 are controlled at 550±5℃, 550±5℃, and 540±5℃, respectively. The oven temperature is controlled at 180±10℃, and the annealing linear speed is controlled at 80±5m / min.

[0105] Wire Bundling: The 650B wire bundling machine is used for wire bundling. The conductor design uses 38 pure copper wires with a diameter of 0.5mm. The wire bundling direction is right-handed, and the wire bundling pitch is controlled between 90mm and 120mm.

[0106] Preparation of inter-screw pressure buffer hollow tube (313): The dried raw material is fed into a single-screw extruder through a conveying device. The temperature parameters of each section are set as follows: feeding section 110℃ to 120℃, compression section 130℃ to 140℃, homogenization section 145℃ to 155℃, and die head temperature 150℃ to 160℃. The screw speed is controlled at 30r / min to 50r / min, and the feeding speed is 5kg / h to 8kg / h to ensure that the raw material is fully melted and plasticized, and the melt pressure is stabilized at 15MPa to 20MPa. The molten material is extruded through the annular die head to form a preliminary hollow tube blank. During the extrusion process, compressed air with a pressure of 0.2MPa to 0.3MPa is introduced through the air passage reserved in the die head to support the tube blank and maintain its hollow structure to prevent collapse.

[0107] Preparation of cable conductor (310): The cable conductor (310) structure adopts fiber rope (312). The innermost layer of the cable conductor (310) consists of 3 strands of conductor (311), such as copper wire, and 3 interstrand pressure buffer hollow tubes (313). The outermost layer consists of 9 strands of copper wire and 3 interstrand pressure buffer hollow tubes (313). The stranding method is that the inner and outermost layers of the cable conductor (310) are all stranded to the left. The pitch of the cable conductor (310) is controlled at 190mm to 230mm and 260mm to 320mm, respectively.

[0108] Insulation: A continuous vulcanization production line (Ф60+Ф150+Ф90) is used to achieve one-time co-extrusion technology for conductor shielding layer (320), insulation layer (330), and insulation shielding layer (340). Ф60 is designed with one layer of 40-mesh filter, Ф150 with three layers of filter (40+80+40), and Ф90 with one layer of 40-mesh filter. After extrusion, high-pressure saturated steam is used for continuous vulcanization, with the steam pressure in the vulcanization pipeline ranging from 1.5MPa to 1.6MPa. The nominal thicknesses of conductor shielding layer (320), insulation layer (330), and insulation shielding layer (340) are designed to be 0.8mm, 10.5mm, and 1.0mm, respectively. The die selection principle for extrusion is: die core aperture = maximum outer diameter of cable core + 0.1mm to 0.5mm; die sleeve inner diameter = average outer diameter of cable core + nominal sheath thickness × 2 - 0.5mm to 2.0mm. Adding 0.1mm to 0.5mm and subtracting 0.5mm to 2.0mm are used to ensure that the cable core passes through smoothly, achieve uniform extrusion layer thickness and tight bonding, and avoid problems such as jamming, scratching and extrusion defects in production.

[0109] Preparation of the inflatable foamed filler layer (400): Composite extrusion molding: The dried inner and outer layer raw materials are fed into the twin-screw barrel of a co-extruder, and the temperatures of each section are set as follows: feeding section 115℃ to 120℃, compression section 132℃ to 140℃, homogenization section 155℃ to 165℃, and composite die head temperature 152℃ to 162℃; the main screw speed is 30r / min to 50r / min, the outer layer material feeding speed is 8kg / h to 10kg / h, and the inner layer material feeding speed is 6kg / h to 8kg / h, to ensure uniform plasticization of the inner and outer layer melts. Nitrogen gas is injected into the inner layer melt through a supercritical gas injection device in the homogenization section at an injection pressure of 2MPa to 4MPa. After the melt and gas are fully mixed, they are compounded with the outer layer melt in the fan-shaped die head to form a fan-shaped billet or a near-fan-shaped billet with a dense outer layer and a flaky inner layer. During the extrusion process, the die head pressure is kept stable at 16MPa to 22MPa. Finally, after shaping and other processes, an inflatable foam filling layer (400) with the required external dimensions is formed.

[0110] Cable Formation: A 3+3 method is adopted, with cable forming in one step using a cable forming machine. Three sets of inflatable foam filling layers (400) are placed between the three core wires (300), evenly distributed at 120 degrees. The cable forming direction is right-handed, and the cable forming pitch is controlled between 950mm and 1200mm. The cable is wrapped with two layers of non-woven fabric, with a wrapping tape width of 70mm and an overlap rate controlled between 15% and 25%. This yields a cable core (200) covered with a wrapping tape layer (510).

[0111] Preparation of the sheath layer (520): Black chlorinated polyethylene rubber is extruded on a Ф150 rubber extruder. The nominal thickness of the rubber is designed to be 6.4 mm. The steam pressure of the vulcanization pipeline is 1.6 MPa to 1.7 MPa. In order to ensure sufficient vulcanization of the sheath, the extrusion speed is controlled between 1.5 m / min and 3.0 m / min. The cable (100) is thus obtained.

[0112] It should be noted that other embodiments of this application also include cables and cable manufacturing methods formed by combining the technical features of the above embodiments.

[0113] 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.

[0114] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the patent protection scope of this application should be determined by the appended claims.

Claims

1. A cable (100), characterized in that, Includes cable core (200) and protective layer (500); Along the length direction (110) of the cable (100), the protective layer (500) covers the outside of the cable core (200); The cable core (200) includes a core wire (300) and an inflatable foam filling layer (400), wherein the inflatable foam filling layer (400) is configured to be pre-filled with fire extinguishing gas and to release the fire extinguishing gas in a preset state; The core wire (300) includes a cable conductor (310) and an insulation structure, wherein the insulation structure covers the cable conductor (310) in the length direction (110); The cable conductor (310) includes a conductor (311) and a cross-strand pressure buffer hollow tube (313), at least one of the cross-strand pressure buffer hollow tubes (313) is located between two adjacent conductors (311), and the cross-strand pressure buffer hollow tube (313) is configured to undergo elastic deformation under compression and to recover when the external force is removed.

2. The cable (100) according to claim 1, characterized in that, Along the length direction (110) of the cable (100), the core wire (300) and the inflatable foam filling layer (400) have a circular cross-section; or, the core wire (300) and the outer edge of the inflatable foam filling layer (400) are located on a circle.

3. The cable (100) according to claim 1, characterized in that, The inflatable foam filling layer (400) includes an inflatable foam filling wall (410) and a pre-filled gas foam body (420). Along the length direction (110) of the cable (100), the inflatable foam filling wall (410) surrounds the pre-filled gas foam (420).

4. The cable (100) according to claim 3, characterized in that, The pre-filled gas foam (420) is pre-filled with carbon dioxide and / or nitrogen, with a pore diameter of 0.1 mm to 1 mm and a gas locking volume of not less than 8.0 cm. 3 / g.

5. The cable (100) according to claim 1, characterized in that, The cable conductor (310) also includes a fiber cord (312) located at the center of the cable conductor (310) in the cross-section along the length direction (110).

6. The cable (100) according to claim 5, characterized in that, In the cross-section, the interstrand pressure buffer hollow tube (313) is arranged in a centrally symmetrical manner with respect to the fiber rope (312).

7. The cable (100) according to claim 1, characterized in that, Along the length direction (110) of the cable (100), the interstrand pressure buffer hollow tube (313) is continuously or intermittently arranged; or, The outer diameter of the hollow tube (313) in the interstrand pressure buffer is 90% to 110% of the outer diameter of the conductor (311); or, At least two of the aforementioned interstrand pressure buffer hollow tubes (313) are arranged as hollow tube strings, and the cable conductor (310) includes at least two of the aforementioned hollow tube strings, wherein each of the hollow tube strings is centrally symmetrically arranged in the cross-section along the length direction (110); or, The conductor (311) comprises a single conductor and a multi-strand strand formed by at least two conductors.

8. The cable (100) according to claim 1, characterized in that, The number of core wires (300) is three, and the number of inflatable foam filling layers (400) is three; and along the length direction (110) of the cable (100), the three core wires (300) are arranged in a centrally symmetrical manner, and the three inflatable foam filling layers (400) are arranged in a centrally symmetrical manner; or, The protective layer (500) includes a wrapping layer (510) and a sheath layer (520) arranged in sequence, wherein the wrapping layer (510) covers the outside of the cable core (200).

9. The cable (100) according to any one of claims 1 to 8, characterized in that, The insulation structure includes a conductor shielding layer (320), an insulation layer (330), an insulation shielding layer (340), and a metal shielding layer (350) arranged in sequence, wherein the conductor shielding layer (320) covers the outside of the cable conductor (310); The conductor shielding layer (320) and the insulating shielding layer (340) are semi-conductive rubber materials. The semi-conductive rubber materials use ethylene propylene rubber as the base material and conductive carbon black as the conductive carrier. The insulating layer (330) comprises hard EPDM rubber or polyether polyurethane; The metal shielding layer (350) includes a metal braided strip.

10. A method for manufacturing a cable, characterized in that, For use in manufacturing the cable (100) as described in any one of claims 1 to 9; the cable manufacturing method includes the steps of: Conductor material drawing; The drawn conductor material is bundled to obtain a wire (311). A hollow tube for inter-strand pressure buffer is formed by extrusion (313). The interstrand pressure buffer hollow tube (313) and the conductor (311) are twisted together to obtain the cable conductor (310). The conductor shielding layer (320), the insulation layer (330) and the insulation shielding layer (340) are co-extruded with the cable conductor (310) to obtain a semi-finished core wire (300); A metal shielding layer (350) is wrapped around the semi-finished product to obtain a core wire (300). The core wire (300) and the air-filled foam filling layer (400) are co-extruded to obtain the cable core (200). A protective layer (500) is wrapped around the cable core (200) to obtain a cable (100).

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