High-voltage flexible cable for aviation power supply and preparation method of high-voltage flexible cable

Abstract

The invention relates to the technical field of cables, and particularly discloses a high-voltage flexible cable for an aviation power supply and a preparation method of the high-voltage flexible cable. The cable is provided with a flexible conductor, and an electric field uniform inner layer, a high-voltage insulating layer, an electric field uniform outer layer, a grounding shielding layer and a sheath layer which are sequentially coated outside the flexible conductor from inside to outside, the flexible conductor is of a structure formed by concentrically twisting and pressing a plurality of annealed copper wires with plating layers; the electric field uniform inner layer is of an overlapped wrapping structure of a polyimide aluminum plastic tape outside the flexible conductor, and the aluminum foil layer faces inwards and is tightly attached to the flexible conductor; the electric field uniform outer layer is of an overlapped wrapping structure of a polyimide aluminum plastic tape outside the high-voltage insulating layer, and the aluminum foil layer faces outwards; and the grounding shielding layer is a braided structure with a plating layer annealed copper wire outside the electric field uniform outer layer, and is tightly attached to the aluminum foil layer. The cable has the characteristics of high voltage resistance, low corona, light weight and high flexibility, and effectively meets the technical requirements of a power supply system of pure electric aviation equipment.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of cables, in particular to a high-voltage flexible cable for an aviation power supply and a preparation method thereof. BACKGROUND

[0002] In recent years, the trend of low-carbonization and electrification of the global aviation industry has become increasingly apparent. Pure electric aviation equipment in the low-altitude field, such as electric helicopters, short-range electric passenger planes, and electric unmanned aerial vehicles, has become an important development direction of the aviation industry due to its zero emissions, low noise, and low operating costs. It provides strong support for urban air transportation, short-distance commuting, and emergency rescue scenarios.

[0003] The core technical requirement of pure electric aviation equipment in the low-altitude field is to achieve efficient and stable transmission of high-power power supplies. As the equipment load increases and the endurance mileage requirement increases, the power of the power supply system has been upgraded from tens of kilowatts to hundreds of kilowatts. Therefore, the pure electric aviation equipment in the low-altitude field has high technical requirements for the voltage adaptation level of the power supply system cable, which should meet the rated working voltage of DC 540V for power transmission.

[0004] To meet the technical requirements of the above-mentioned pure electric aviation equipment for power supply system cables, it is necessary to improve the transmission voltage level of power supply cables to meet the rated working voltage of DC 540V. However, increasing the transmission voltage level of power supply cables according to technical requirements will result in prominent corona discharge technical problems. When the transmission voltage of the power supply cable is increased to DC 540V, the electric field distribution on the surface of the conductor is uneven, resulting in corona discharge. On the one hand, about 15% to 20% of the electric energy is lost. On the other hand, the ozone produced will accelerate the aging of the insulation layer. On the third hand, the electromagnetic interference produced will affect the precision electronic control system of the aviation equipment (such as the flight control system and the battery management system). Therefore, the high-voltage cable that meets the technical requirements of the above-mentioned pure electric aviation equipment power supply system should have an anti-corona structure.

[0005] In the disclosed technology, the anti-corona structure used in the disclosed aviation high-voltage cable is mostly a multi-layer high-temperature sintering structure of anti-corona insulation material, such as the technology disclosed in the Chinese patent document entitled "Composite Insulated Wire Cable for Aviation with Rated Voltage 1000V Series" and with publication number CN 116487091 A and publication date July 25, 2023. However, such aviation high-voltage cables have relatively limited anti-corona performance, and their softness is not good, the cross-sectional structure size is large, and the weight per unit length is heavy, making it difficult to effectively meet the working conditions of the power supply system of the above-mentioned pure electric aviation equipment.

[0006] This is because the power supply system of the above-mentioned pure electric aviation equipment has narrow space and complex wiring path, and the power cable needs to form a compact winding of different paths among the battery pack, the power motor, the control system and other components in the narrow space. The cable with poor flexibility and large cross-sectional structure size not only increases the installation difficulty, but also may cause the cracking of the insulation layer and other structures due to bending stress, thereby causing safety hazards. In addition, the cable with heavy weight per unit length will affect the endurance mileage and load capacity of the above-mentioned pure electric aviation equipment. SUMMARY

[0007] The technical purpose of the present application is to provide a high-voltage flexible cable for aviation power supply, which is resistant to high voltage, low corona, lightweight, resistant to high and low temperature, and high flexible, in view of the particularity of the technical requirements of the power cable for the above-mentioned low-altitude pure electric aviation equipment and the shortcomings of the prior art.

[0008] The technical purpose of the present application is achieved by the following technical scheme: a high-voltage flexible cable for aviation power supply, the cable has a flexible conductor and an electric field uniform inner layer, a high-voltage insulation layer, an electric field uniform outer layer, a grounding shielding layer and a sheath layer which are sequentially covered outside the flexible conductor from inside to outside. The flexible conductor is a concentric twisted and compressed structure of a plurality of plated soft copper wires. The electric field uniform inner layer is an overlapping wrapping structure of polyimide aluminum plastic tape outside the flexible conductor, and the aluminum foil layer of the polyimide aluminum plastic tape overlapping wrapped outside the flexible conductor faces inward and closely adheres to the flexible conductor. The electric field uniform outer layer is an overlapping wrapping structure of polyimide aluminum plastic tape outside the high-voltage insulation layer, and the aluminum foil layer of the polyimide aluminum plastic tape overlapping wrapped outside the high-voltage insulation layer faces outward. The grounding shielding layer is a braided structure of plated soft copper wires outside the electric field uniform outer layer, and the grounding shielding layer closely adheres to the aluminum foil layer of the covered electric field uniform outer layer.

[0009] Further, the plated soft copper wire of the flexible conductor is a circular cross-sectional structure, and the plating layer of the plated soft copper wire is a tin plating layer structure, a silver plating layer structure or a nickel plating layer structure.

[0010] Further, the single wire diameter of the plated soft copper wire of the flexible conductor is any one of 0.10mm, 0.12mm, 0.15mm, 0.20mm, 0.26mm, 0.28mm, 0.32mm, 0.36mm, 0.40mm or 0.45mm. The concentric twisted pitch ratio of the plurality of plated soft copper wires constituting the flexible conductor is 10 to 12 times, and the compression coefficient after twisting is 8% to 12%.

[0011] Further, the polyimide aluminum plastic tape of the electric field uniform inner layer has a nominal thickness of 0.05 mm and a width greater than the circumference of the flexible conductor; The polyimide aluminum plastic tape constituting the electric field uniform inner layer is overlapped and wrapped around the outside of the flexible conductor with a 50% or 66.66% overlap rate.

[0012] Further, the high-voltage insulation layer is a flexible cross-linked ethylene-tetrafluoroethylene copolymer extruded around the outside of the electric field uniform inner layer, and has a nominal thickness of 0.25 mm to 0.35 mm and a concentricity of greater than or equal to 90%.

[0013] Further, the polyimide aluminum plastic tape of the electric field uniform outer layer has a nominal thickness of 0.05 mm and a width greater than the circumference of the high-voltage insulation layer; The polyimide aluminum plastic tape constituting the electric field uniform outer layer is overlapped and wrapped around the outside of the high-voltage insulation layer with a 50% or 66.66% overlap rate.

[0014] Further, the plated soft copper wire of the ground shielding layer has a circular cross-sectional structure, and the plating layer of the plated soft copper wire is a tin plating layer structure, a silver plating layer structure, or a nickel plating layer structure.

[0015] Further, the plated soft copper wire of the ground shielding layer has a single wire diameter of 0.06 mm, and the braided coverage density outside the electric field uniform outer layer is greater than or equal to 85% and the braiding angle is 50° to 70°.

[0016] Further, the sheath layer is a flexible cross-linked ethylene-tetrafluoroethylene copolymer extruded around the outside of the ground shielding layer, and has a nominal thickness of 0.25 mm to 0.35 mm and a concentricity of greater than or equal to 90%.

[0017] A preparation method of the above-mentioned high-voltage flexible cable for aviation power supply, the preparation method comprising the following process steps: Step 1. According to the design specifications, a plurality of plated soft copper wires are twisted into a bundle in a concentric structure, and the twisting pitch ratio is controlled to be 10 to 12 times. During the twisting process, the structure of the twisted bundle is compressed to make the compression coefficient 8% to 12%, and a flexible conductor is obtained. Step 2. A polyimide aluminum plastic tape with a nominal thickness of 0.05 mm and a width not less than the circumference of the flexible conductor is overlapped and wrapped around the outer surface of the flexible conductor with a 50% or 66.66% overlap rate, with the aluminum foil layer facing inward and tightly adhering to the wrapped flexible conductor, to obtain an electric field uniform inner layer. Step 3. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. With a nominal thickness of not less than 0.20 mm and a concentricity of not less than 90%, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated on the outer surface of the inner layer with a uniform electric field. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature from the feed end to the extrusion die is 255℃~265℃, and the linear speed of the extrusion process is 10m / min~20m / min. Step 4. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer to be coated is cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain a high-voltage insulating layer; Step 5. Use polyimide aluminum-plastic tape with a nominal thickness of 0.05mm and a width not less than the perimeter of the high-voltage insulation layer, and wrap it around the outer surface of the high-voltage insulation layer with the aluminum foil layer facing outward, according to a 50% or 66.66% overlap rate, to obtain a uniform electric field outer layer. Step 6. Select a plated soft copper wire with a nominal diameter of 0.06mm; A grounding shield layer is covered on the outer surface of the uniform electric field outer layer in the form of a woven mesh, with a woven coverage density of ≥85% and a weaving angle of 50°~70°. Step 7. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. With a nominal thickness of not less than 0.20 mm and a concentricity of not less than 90%, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated onto the outer surface of the grounding shield layer. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature from the feed end to the extrusion die is 255℃~265℃, and the linear speed of the extrusion process is 10m / min~20m / min. Step 8. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer coated in Step 7 has cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain the sheath layer; This resulted in the production of high-voltage, flexible finished cables for aviation power supplies.

[0018] The beneficial technical effects of the present invention are as follows: The above-mentioned technical measures are aimed at the special requirements of power system cable technology for pure electric aviation equipment in the low-altitude field. A flexible conductor that meets the requirements of high voltage transmission is formed by stranding and compressing coated soft copper wire. A polyimide aluminum-plastic tape with aluminum foil layers tightly bonded and overlapping is formed to form a uniform electric field inner layer. A high-voltage insulation layer is formed by extruding a flexible cross-linked ethylene-tetrafluoroethylene copolymer with high voltage resistance and excellent insulation performance outside the uniform electric field inner layer. A uniform electric field outer layer is formed by extruding a polyimide aluminum-plastic tape with aluminum foil layers facing outward and overlapping outside the high-voltage insulation layer. A flexible grounding shield layer that meets the requirements of high voltage transmission is formed by braiding coated soft copper wire outside the uniform electric field outer layer and tightly bonding it with the corresponding aluminum foil layer. A sheath layer is formed by extruding a flexible cross-linked ethylene-tetrafluoroethylene copolymer with high voltage resistance and excellent insulation performance outside the grounding shield layer. Thus, the present invention provides a cable with high voltage resistance, low corona discharge, lightweight, and high flexibility, which meets the technical requirements of the power system for power transmission and wiring space of pure electric aviation equipment in the low-altitude field. According to the test, the rated operating voltage of the cable of the present invention is DC540V and the corona discharge voltage is not less than 500V.

[0019] Specifically, the above-mentioned flexible conductor molding structure of the present invention can effectively avoid the phenomenon of tip discharge while meeting the requirements of high voltage power transmission technology and obtain excellent flexibility.

[0020] The above-mentioned uniform electric field inner layer of the present invention is based on a "conductive-insulating" composite polyimide aluminum-plastic tape structure. This structure allows the aluminum foil layer of the polyimide aluminum-plastic tape to form an "equipotential shielding structure layer" on the surface of the flexible conductor. This effectively eliminates electric field concentration caused by burrs and sharp edges on the flexible conductor surface, resulting in a uniform gradient distribution of the electric field from the flexible conductor outwards. This reduces the partial discharge threshold from the source, reliably ensuring that the electric field on the surface of the flexible conductor remains uniform throughout its length and circumference, preventing corona discharge when high-voltage current passes through the flexible conductor. This demonstrates the anti-corona properties of the polyimide aluminum-plastic tape. Simultaneously, the polyimide layer effectively isolates moisture and chemical media, preventing oxidation of the aluminum foil layer and high-voltage insulation layer, and preventing moisture from penetrating the conductor. The high dielectric stability of the polyimide substrate in the uniform electric field inner layer, combined with the conductive uniformity of the aluminum foil layer, effectively makes the anti-corona uniform electric field inner layer an "electric field buffer zone," effectively mitigating the abrupt change in dielectric constant between the high-voltage insulation layer and the flexible conductor, further optimizing the electric field distribution.

[0021] The high-voltage insulation layer of the present invention has a thin and light structure while ensuring high voltage resistance and electrical insulation, which effectively supports the weight reduction and outer diameter control of the formed cable.

[0022] The uniform electric field outer layer of this invention is based on a "conductive-insulating" composite polyimide-aluminum-plastic tape structure. The polyimide layer effectively isolates moisture and chemical media, preventing oxidation of the high-voltage insulation layer. Simultaneously, it creates an equipotential interface between the aluminum foil layer of the polyimide-aluminum-plastic tape and the external grounding shield layer. This effectively prevents electric field distortion on the surface of the high-voltage insulation layer due to environmental humidity and dust, and effectively blocks external electric field interference to the interior of the high-voltage insulation layer. Combined with the uniform electric field inner layer, this achieves "bidirectional electric field regularization," effectively enhancing the anti-corona technology effect of the formed cable during high-voltage transmission and preventing corona discharge. Furthermore, the uniform electric field inner layer reliably protects the high-voltage insulation layer extruded in the middle, ensuring that both the inner and outer surfaces of the high-voltage insulation layer remain smooth and flat, preventing point discharge and reliably guaranteeing the high-voltage resistance and electrical insulation performance of the high-voltage insulation layer. The high dielectric stability of the polyimide substrate with a uniform electric field outer layer is effectively combined with the conductivity uniformity of the aluminum foil layer, making the corona-resistant uniform electric field outer layer an "electric field buffer zone". This effectively alleviates the abrupt change in dielectric constant between the high voltage insulation layer and the grounding shield layer, and further optimizes the electric field distribution.

[0023] Furthermore, the arrangement of the uniform electric field inner layer and the uniform electric field outer layer in the high-voltage insulation layer of the present invention creates a "closed-loop protection" effect between the inner and outer double aluminum foil layers. Even if the aluminum foil layer of the uniform electric field inner layer is partially damaged, the aluminum foil layer of the uniform electric field outer layer can still quickly conduct abnormal charges through the grounding of the grounding shield layer, preventing the discharge phenomenon from spreading into the high-voltage insulation layer and effectively improving structural redundancy and reliability.

[0024] The grounding shielding layer of the present invention has a molding structure that satisfies the grounding and shielding functions while having excellent flexibility, which is beneficial to ensuring the voltage resistance and flexibility of the molded cable.

[0025] The above-mentioned sheath layer molding structure of the present invention has high voltage resistance, electrical insulation performance, good environmental resistance, and thin and light structural characteristics. While fulfilling the sheath function, it provides effective support for weight reduction and outer diameter control of the molded cable.

[0026] In summary, the cable structure of this invention features high voltage resistance, low corona discharge, lightweight design, and high flexibility. Furthermore, the synergy between the various molded structural layers of the cable enables it to exhibit excellent high and low temperature resistance, extending its long-term operating temperature range to -65℃ to +200℃, thus covering the full range of operating conditions required for pure electric aviation equipment in low-altitude environments, from frigid conditions to high-temperature areas near engines. Attached Figure Description

[0027] Figure 1This is a schematic diagram of one structure of the present invention; The symbols in the diagram mean: 1—conductor; 2—inner layer with uniform electric field; 3—high voltage insulation layer; 4—outer layer with uniform electric field; 5—grounding shielding layer; 6—sheath layer. Detailed Implementation

[0028] This invention relates to the field of cable technology, specifically to a high-voltage, low-corona, lightweight, high- and low-temperature resistant, and highly flexible cable used in the power system of pure electric aircraft equipment in low-altitude environments, as well as a method for manufacturing this cable. The main technical solution of this invention will be specifically described below with reference to several embodiments. Embodiment 1 is illustrated in conjunction with the accompanying drawings—that is… Figure 1 The technical solution of the present invention will be clearly and thoroughly explained; although other embodiments are not shown in separate drawings, their main structure can still be referred to the drawings of Embodiment 1.

[0029] It should be noted that the accompanying drawings of this invention are schematic, and unnecessary details have been simplified to clarify the technical objectives of this invention, so as to avoid obscuring the technical solutions contributed by this invention to the prior art. Furthermore, the terms "approximately" or "basically" used below to refer to quantities or fit relationships mean that reasonable assembly and processing errors are allowed in the industry, and do not literally describe absolute quantities or fit relationships.

[0030] Example 1 The present invention provides a power transmission cable for the power system of pure electric aircraft equipment in the low-altitude field, which has a flexible conductor 1 and, from the inside out, a uniform electric field inner layer 2, a high voltage insulation layer 3, a uniform electric field outer layer 4, a grounding shield layer 5, and a sheath layer 6 that are sequentially wrapped around the flexible conductor 1.

[0031] Specifically, the plated soft copper wire of the flexible conductor 1 has a circular cross-section, and the plating on the plated soft copper wire is a tin-plated layer. Depending on the magnitude of the current to be transmitted and the number of plated soft copper wires, the diameter of each wire is 0.10 mm. The multiple plated soft copper wires constituting the flexible conductor 1 are arranged concentrically, typically increasing by six wires layer by layer (excluding the central wire), for example, 49 wires. These plated soft copper wires are formed by concentric stranding, with a stranding pitch ratio of approximately 10. The stranded structure is compressed, with a compression factor of approximately 10%. In other words, the flexible conductor 1 is a concentrically stranded and compressed structure of multiple plated soft copper wires.

[0032] The uniform electric field inner layer 2 is an overlapping wrapping structure of polyimide aluminum-plastic tape outside the flexible conductor 1. The polyimide aluminum-plastic tape is a composite structure of a conductive aluminum foil layer and an insulating polyimide substrate layer, forming a "conductive-insulating" composite structure. It possesses characteristics of high temperature resistance, aging resistance, electrical corrosion resistance, and corona resistance. When it is overlapped and wrapped around the flexible conductor 1 to form the uniform electric field inner layer 2, the aluminum foil layer of the polyimide aluminum-plastic tape faces inward and is tightly adhered to the surface of the flexible conductor 1, thereby effectively eliminating electric field concentration caused by burrs and sharp edges on the surface of the flexible conductor 1. The aforementioned polyimide aluminum-plastic tape constituting the uniform electric field inner layer 2 has a nominal thickness of 0.05 mm and a width not less than the circumference of the flexible conductor 1. Its overlap rate on the outside of the flexible conductor 1 is 50%. This overlap rate effectively eliminates butt joint gaps, ensuring surface flatness and eliminating pores from which corona can escape.

[0033] The high-voltage insulation layer 3 is an extrusion structure of flexible cross-linked ethylene-tetrafluoroethylene copolymer (XETFE) outside the uniform electric field inner layer 2. The nominal thickness of the extrusion is about 0.25 mm and the concentricity is about 92%.

[0034] The uniform electric field outer layer 4 is an overlapping wrapping structure of polyimide aluminum-plastic tape outside the high-voltage insulation layer 3. As mentioned above, the polyimide aluminum-plastic tape is a composite structure of a conductive aluminum foil layer and an insulating polyimide substrate layer. When it is overlapped and wrapped outside the high-voltage insulation layer 3 to form the uniform electric field outer layer 4, it needs to be used in conjunction with an external grounding shielding layer 5. Therefore, the aluminum foil layer of the polyimide aluminum-plastic tape faces outward. The aforementioned polyimide aluminum-plastic tape constituting the uniform electric field outer layer 4 has a nominal thickness of 0.05 mm and a width not less than the perimeter of the high-voltage insulation layer 3. Its overlap rate outside the high-voltage insulation layer 3 is 50%. The overlapping wrapping structure formed by this overlap rate can effectively eliminate butt joint gaps, ensure surface flatness, and eliminate the porosity of corona escape.

[0035] The grounding shielding layer 5 is a braided structure of plated soft copper wire outside the uniform electric field outer layer 4. The plated soft copper wire of the grounding shielding layer 5 has a circular cross-section, and the plating of the plated soft copper wire is a tin-plated layer. The diameter of a single wire of the plated soft copper wire is 0.06 mm. Its braiding coverage density outside the uniform electric field outer layer 4 is about 88%, the braiding angle is about 60°, and it forms a tight fit with the aluminum foil layer of the inner uniform electric field outer layer 4.

[0036] The sheath layer 6 is an extruded structure of flexible cross-linked ethylene-tetrafluoroethylene copolymer (XETFE) outside the grounding shield layer 5. The nominal thickness of the extrusion is about 0.25 mm and the concentricity is about 92%.

[0037] The cable with the above structure is prepared by the following process steps: Step 1. According to the design specifications, twist multiple coated soft copper wires into a bundle with the twisting pitch ratio set above and in a concentric structure. During the stranding process, the stranded bundle structure is compressed using the aforementioned compression coefficient to obtain a flexible conductor; Step 2. Using polyimide aluminum-plastic tape with a nominal thickness of 0.05 mm and a width not less than the circumference of the flexible conductor, according to the above-set seam overlap rate, the aluminum foil layer is wrapped around the outer surface of the flexible conductor with the aluminum foil layer facing inward and in close contact with the surface of the flexible conductor to obtain a uniform electric field inner layer. Step 3. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. According to the nominal thickness and concentricity set above, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated on the outer surface of the electric field uniform inner layer. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature is in the range of 255℃~265℃ from the feed end to the extrusion die, and the linear speed of the extrusion process is about 10m / min. Step 4. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer to be coated is cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain a high-voltage insulating layer; Step 5. Using polyimide aluminum-plastic tape with a nominal thickness of 0.05 mm and a width not less than the perimeter of the high-voltage insulation layer, wrap it around the outer surface of the high-voltage insulation layer with the aluminum foil layer facing outwards, according to the seam overlap rate set above, to obtain a uniform electric field outer layer. Step 6. Select the corresponding plated soft copper wire according to the above specifications; A braided net is woven on the outer surface of the uniform electric field layer using a braiding machine, and a grounding shielding layer is then covered on the outer surface of the uniform electric field layer. Step 7. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. According to the nominal thickness and concentricity set above, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated on the outer surface of the grounding shield layer. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature is in the range of 255℃~265℃ from the feed end to the extrusion die, and the linear speed of the extrusion process is about 10m / min. Step 8. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer coated in Step 7 has cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain the sheath layer; This provides us with finished cables that are resistant to high voltage, low corona, lightweight, highly flexible, and resistant to high and low temperatures, suitable for the power systems of pure electric aircraft equipment in the low-altitude field.

[0038] Example 2 The present invention relates to a power transmission cable for a power system of pure electric aircraft equipment in the low-altitude field, which has a flexible conductor and, from the inside out, a uniform electric field inner layer, a high-voltage insulation layer, a uniform electric field outer layer, a grounding shield layer, and a sheath layer that are sequentially wrapped around the flexible conductor.

[0039] Specifically, the plated soft copper wire of the flexible conductor has a circular cross-section, and the plating is a silver plating layer. Depending on the magnitude of the current transmitted and the number of plated soft copper wires, the diameter of each wire is 0.12 mm. The multiple plated soft copper wires that make up the flexible conductor are arranged concentrically, typically increasing by six wires layer by layer after the central wire, for example, 37 wires. These plated soft copper wires are formed by concentric stranding, with a stranding pitch ratio of approximately 12. The stranded structure is compressed, with a compression factor of approximately 12%. In other words, the flexible conductor is a structure of multiple concentrically stranded and compressed plated soft copper wires.

[0040] The uniform electric field inner layer is a polyimide-aluminum composite tape overlapping and wrapping structure around the flexible conductor. The polyimide-aluminum composite tape is a composite structure of a conductive aluminum foil layer and an insulating polyimide substrate layer, forming a "conductive-insulating" composite structure. It possesses characteristics of high temperature resistance, aging resistance, electrical corrosion resistance, and corona resistance. When it is overlapped and wrapped around the flexible conductor to form the uniform electric field inner layer, the aluminum foil layer of the polyimide-aluminum composite tape faces inward and is tightly adhered to the surface of the flexible conductor, effectively eliminating electric field concentration caused by burrs and sharp edges on the flexible conductor surface. The aforementioned polyimide-aluminum composite tape constituting the uniform electric field inner layer has a nominal thickness of 0.05 mm and a width not less than the circumference of the flexible conductor. Its overlap rate on the outside of the flexible conductor is 66.66%. This overlap rate effectively eliminates butt joint gaps, ensuring surface flatness and eliminating porosity from corona discharge.

[0041] The high-voltage insulation layer is an extrusion structure of flexible cross-linked ethylene-tetrafluoroethylene copolymer (XETFE) on the outside of the uniform electric field inner layer. The nominal thickness of the extrusion is about 0.35 mm and the concentricity is about 90%.

[0042] The uniform electric field outer layer is a polyimide aluminum-plastic tape overlapping and wrapping structure outside the high-voltage insulation layer. As mentioned above, the polyimide aluminum-plastic tape is a composite structure of a conductive aluminum foil layer and an insulating polyimide substrate layer. When it is overlapped and wrapped outside the high-voltage insulation layer to form the uniform electric field outer layer, it needs to be used in conjunction with an external grounding shielding layer. Therefore, the aluminum foil layer of the polyimide aluminum-plastic tape faces outward. The aforementioned polyimide aluminum-plastic tape constituting the uniform electric field outer layer has a nominal thickness of 0.05 mm and a width not less than the perimeter of the high-voltage insulation layer. Its overlap rate outside the high-voltage insulation layer is 66.66%. The overlapping and wrapping structure formed by this overlap rate can effectively eliminate butt joint gaps, ensure surface flatness, and eliminate porosity for corona escape.

[0043] The grounding shielding layer is a braided structure of plated soft copper wire outside the uniform electric field outer layer. The plated soft copper wire of the grounding shielding layer has a circular cross-section structure, and the plating of the plated soft copper wire is a silver-plated structure. The diameter of the single wire of the plated soft copper wire is 0.06mm. Its braiding coverage density outside the uniform electric field outer layer is about 85%, the braiding angle is about 50°, and it forms a tight fit with the aluminum foil layer of the inner uniform electric field outer layer.

[0044] The sheath layer is an extruded structure of flexible cross-linked ethylene-tetrafluoroethylene copolymer (XETFE) outside the grounding shield layer. The nominal thickness of the extrusion is about 0.35 mm and the concentricity is about 90%.

[0045] The cable with the above structure is prepared by the following process steps: Step 1. According to the design specifications, twist multiple coated soft copper wires into a bundle with the twisting pitch ratio set above and in a concentric structure. During the stranding process, the stranded bundle structure is compressed using the aforementioned compression coefficient to obtain a flexible conductor; Step 2. Using polyimide aluminum-plastic tape with a nominal thickness of 0.05 mm and a width not less than the circumference of the flexible conductor, according to the above-set seam overlap rate, the aluminum foil layer is wrapped around the outer surface of the flexible conductor with the aluminum foil layer facing inward and in close contact with the surface of the flexible conductor to obtain a uniform electric field inner layer. Step 3. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. According to the nominal thickness and concentricity set above, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated on the outer surface of the electric field uniform inner layer. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature is in the range of 255℃~265℃ from the feed end to the extrusion die, and the linear speed of the extrusion process is about 20m / min. Step 4. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer to be coated is cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain a high-voltage insulating layer; Step 5. Using polyimide aluminum-plastic tape with a nominal thickness of 0.05 mm and a width not less than the perimeter of the high-voltage insulation layer, wrap it around the outer surface of the high-voltage insulation layer with the aluminum foil layer facing outwards, according to the seam overlap rate set above, to obtain a uniform electric field outer layer. Step 6. Select the corresponding plated soft copper wire according to the above specifications; A braided net is woven on the outer surface of the uniform electric field layer using a braiding machine, and a grounding shielding layer is then covered on the outer surface of the uniform electric field layer. Step 7. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. According to the nominal thickness and concentricity set above, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated on the outer surface of the grounding shield layer. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature is in the range of 255℃~265℃ from the feed end to the extrusion die, and the linear speed of the extrusion process is about 20m / min. Step 8. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer coated in Step 7 has cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain the sheath layer; This provides us with finished cables that are resistant to high voltage, low corona, lightweight, highly flexible, and resistant to high and low temperatures, suitable for the power systems of pure electric aircraft equipment in the low-altitude field.

[0046] Example 3 The present invention relates to a power transmission cable for a power system of pure electric aircraft equipment in the low-altitude field, which has a flexible conductor and, from the inside out, a uniform electric field inner layer, a high-voltage insulation layer, a uniform electric field outer layer, a grounding shield layer, and a sheath layer that are sequentially wrapped around the flexible conductor.

[0047] Specifically, the plated soft copper wire of the flexible conductor has a circular cross-section, and the plating on the plated soft copper wire is a nickel-plated layer. Depending on the magnitude of the current transmitted, and considering the number of plated soft copper wires, the diameter of each wire is 0.15 mm. The multiple plated soft copper wires that make up the flexible conductor are arranged concentrically, typically increasing by six wires layer by layer after the central wire, for example, 19 wires. These plated soft copper wires are formed by concentric stranding, with a stranding pitch ratio of approximately 12. The stranded structure is compressed, with a compression factor of approximately 8%, meaning the flexible conductor is a structure of multiple concentrically stranded and compressed plated soft copper wires.

[0048] The uniform electric field inner layer is a polyimide-aluminum composite tape overlapping and wrapping structure on the outside of the flexible conductor. The polyimide-aluminum composite tape is a composite structure of a conductive aluminum foil layer and an insulating polyimide substrate layer, forming a "conductive-insulating" composite structure. It possesses characteristics of high temperature resistance, aging resistance, electrical corrosion resistance, and corona resistance. When it is overlapped and wrapped around the outside of the flexible conductor to form the uniform electric field inner layer, the aluminum foil layer of the polyimide-aluminum composite tape faces inward and is tightly adhered to the surface of the flexible conductor, effectively eliminating electric field concentration caused by burrs and sharp edges on the flexible conductor surface. The aforementioned polyimide-aluminum composite tape constituting the uniform electric field inner layer has a nominal thickness of 0.05 mm and a width not less than the circumference of the flexible conductor. Its overlap rate on the outside of the flexible conductor is 50%. This overlap rate effectively eliminates butt joint gaps, ensuring surface flatness and eliminating porosity from corona discharge.

[0049] The high-voltage insulation layer is an extrusion structure of flexible cross-linked ethylene-tetrafluoroethylene copolymer (XETFE) on the outside of the uniform electric field inner layer. The nominal thickness of the extrusion is about 0.30 mm and the concentricity is about 95%.

[0050] The uniform electric field outer layer is a polyimide aluminum-plastic tape overlapping and wrapping structure outside the high-voltage insulation layer. As mentioned above, the polyimide aluminum-plastic tape is a composite structure of a conductive aluminum foil layer and an insulating polyimide substrate layer. When it is overlapped and wrapped outside the high-voltage insulation layer to form the uniform electric field outer layer, it needs to be used in conjunction with an external grounding shielding layer. Therefore, the aluminum foil layer of the polyimide aluminum-plastic tape faces outward. The aforementioned polyimide aluminum-plastic tape constituting the uniform electric field outer layer has a nominal thickness of 0.05 mm and a width not less than the perimeter of the high-voltage insulation layer. Its overlap rate outside the high-voltage insulation layer is 50%. The overlapping and wrapping structure formed by this overlap rate can effectively eliminate butt joint gaps, ensure surface flatness, and eliminate porosity for corona escape.

[0051] The grounding shielding layer is a braided structure of plated soft copper wire outside the uniform electric field outer layer. The plated soft copper wire of the grounding shielding layer has a circular cross-section structure, and the plating of the plated soft copper wire is a nickel-plated structure. The diameter of the single wire of the plated soft copper wire is 0.06mm. Its braiding coverage density outside the uniform electric field outer layer is about 90%, the braiding angle is about 70°, and it forms a tight fit with the aluminum foil layer of the inner uniform electric field outer layer.

[0052] The sheath layer is an extruded structure of flexible cross-linked ethylene-tetrafluoroethylene copolymer (XETFE) outside the grounding shield layer. The nominal thickness of the extrusion is about 0.30 mm and the concentricity is about 95%.

[0053] The cable with the above structure is prepared by the following process steps: Step 1. According to the design specifications, twist multiple coated soft copper wires into a bundle with the twisting pitch ratio set above and in a concentric structure. During the stranding process, the stranded bundle structure is compressed using the aforementioned compression coefficient to obtain a flexible conductor; Step 2. Using polyimide aluminum-plastic tape with a nominal thickness of 0.05 mm and a width not less than the circumference of the flexible conductor, according to the above-set seam overlap rate, the aluminum foil layer is wrapped around the outer surface of the flexible conductor with the aluminum foil layer facing inward and in close contact with the surface of the flexible conductor to obtain a uniform electric field inner layer. Step 3. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. According to the nominal thickness and concentricity set above, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated on the outer surface of the electric field uniform inner layer. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature is in the range of 255℃~265℃ from the feed end to the extrusion die, and the linear speed of the extrusion process is about 15m / min. Step 4. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer to be coated is cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain a high-voltage insulating layer; Step 5. Using polyimide aluminum-plastic tape with a nominal thickness of 0.05 mm and a width not less than the perimeter of the high-voltage insulation layer, wrap it around the outer surface of the high-voltage insulation layer with the aluminum foil layer facing outwards, according to the seam overlap rate set above, to obtain a uniform electric field outer layer. Step 6. Select the corresponding plated soft copper wire according to the above specifications; A braided net is woven on the outer surface of the uniform electric field layer using a braiding machine, and a grounding shielding layer is then covered on the outer surface of the uniform electric field layer. Step 7. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. According to the nominal thickness and concentricity set above, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated on the outer surface of the grounding shield layer. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature is in the range of 255℃~265℃ from the feed end to the extrusion die, and the linear speed of the extrusion process is about 15m / min. Step 8. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer coated in Step 7 has cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain the sheath layer; This provides us with finished cables that are resistant to high voltage, low corona, lightweight, highly flexible, and resistant to high and low temperatures, suitable for the power systems of pure electric aircraft equipment in the low-altitude field.

[0054] Example 4 The present invention relates to a power transmission cable for a power system of pure electric aircraft equipment in the low-altitude field, which has a flexible conductor and, from the inside out, a uniform electric field inner layer, a high-voltage insulation layer, a uniform electric field outer layer, a grounding shield layer, and a sheath layer that are sequentially wrapped around the flexible conductor.

[0055] Specifically, the plated soft copper wire of the flexible conductor has a circular cross-section, and the plating is a silver plating layer. Depending on the magnitude of the current transmitted and the number of plated soft copper wires, the diameter of each wire is 0.45 mm. The multiple plated soft copper wires that make up the flexible conductor are arranged concentrically, typically increasing by six wires layer by layer (e.g., seven wires). These wires are formed by concentric stranding with a stranding pitch ratio of approximately 10. The stranded structure is compressed with a compression factor of approximately 10%, meaning the flexible conductor is a concentrically stranded and compressed structure of multiple plated soft copper wires.

[0056] The uniform electric field inner layer is a polyimide-aluminum composite tape overlapping and wrapping structure around the flexible conductor. The polyimide-aluminum composite tape is a composite structure of a conductive aluminum foil layer and an insulating polyimide substrate layer, forming a "conductive-insulating" composite structure. It possesses characteristics of high temperature resistance, aging resistance, electrical corrosion resistance, and corona resistance. When it is overlapped and wrapped around the flexible conductor to form the uniform electric field inner layer, the aluminum foil layer of the polyimide-aluminum composite tape faces inward and is tightly adhered to the surface of the flexible conductor, effectively eliminating electric field concentration caused by burrs and sharp edges on the flexible conductor surface. The aforementioned polyimide-aluminum composite tape constituting the uniform electric field inner layer has a nominal thickness of 0.05 mm and a width not less than the circumference of the flexible conductor. Its overlap rate on the outside of the flexible conductor is 66.66%. This overlap rate effectively eliminates butt joint gaps, ensuring surface flatness and eliminating porosity from corona discharge.

[0057] The high-voltage insulation layer is an extrusion structure of flexible cross-linked ethylene-tetrafluoroethylene copolymer (XETFE) on the outside of the uniform electric field inner layer. The nominal thickness of the extrusion is about 0.25 mm and the concentricity is about 90%.

[0058] The uniform electric field outer layer is a polyimide aluminum-plastic tape overlapping and wrapping structure outside the high-voltage insulation layer. As mentioned above, the polyimide aluminum-plastic tape is a composite structure of a conductive aluminum foil layer and an insulating polyimide substrate layer. When it is overlapped and wrapped outside the high-voltage insulation layer to form the uniform electric field outer layer, it needs to be used in conjunction with an external grounding shielding layer. Therefore, the aluminum foil layer of the polyimide aluminum-plastic tape faces outward. The aforementioned polyimide aluminum-plastic tape constituting the uniform electric field outer layer has a nominal thickness of 0.05 mm and a width not less than the perimeter of the high-voltage insulation layer. Its overlap rate outside the high-voltage insulation layer is 66.66%. The overlapping and wrapping structure formed by this overlap rate can effectively eliminate butt joint gaps, ensure surface flatness, and eliminate porosity for corona escape.

[0059] The grounding shielding layer is a braided structure of plated soft copper wire outside the uniform electric field outer layer. The plated soft copper wire of the grounding shielding layer has a circular cross-section structure, and the plating of the plated soft copper wire is a silver-plated structure. The diameter of the single wire of the plated soft copper wire is 0.06mm. Its braiding coverage density outside the uniform electric field outer layer is about 85%, the braiding angle is about 65°, and it forms a tight fit with the aluminum foil layer of the inner uniform electric field outer layer.

[0060] The sheath layer is an extruded structure of flexible cross-linked ethylene-tetrafluoroethylene copolymer (XETFE) outside the grounding shield layer. The nominal thickness of the extrusion is about 0.25 mm and the concentricity is about 90%.

[0061] The cable with the above structure is prepared by the following process steps: Step 1. According to the design specifications, twist multiple coated soft copper wires into a bundle with the twisting pitch ratio set above and in a concentric structure. During the stranding process, the stranded bundle structure is compressed using the aforementioned compression coefficient to obtain a flexible conductor; Step 2. Using polyimide aluminum-plastic tape with a nominal thickness of 0.05 mm and a width not less than the circumference of the flexible conductor, according to the above-set seam overlap rate, the aluminum foil layer is wrapped around the outer surface of the flexible conductor with the aluminum foil layer facing inward and in close contact with the surface of the flexible conductor to obtain a uniform electric field inner layer. Step 3. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. According to the nominal thickness and concentricity set above, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated on the outer surface of the electric field uniform inner layer. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature is in the range of 255℃~265℃ from the feed end to the extrusion die, and the linear speed of the extrusion process is about 12m / min. Step 4. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer to be coated is cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain a high-voltage insulating layer; Step 5. Using polyimide aluminum-plastic tape with a nominal thickness of 0.05 mm and a width not less than the perimeter of the high-voltage insulation layer, wrap it around the outer surface of the high-voltage insulation layer with the aluminum foil layer facing outwards, according to the seam overlap rate set above, to obtain a uniform electric field outer layer. Step 6. Select the corresponding plated soft copper wire according to the above specifications; A braided net is woven on the outer surface of the uniform electric field layer using a braiding machine, and a grounding shielding layer is then covered on the outer surface of the uniform electric field layer. Step 7. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. According to the nominal thickness and concentricity set above, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated on the outer surface of the grounding shield layer. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature is in the range of 255℃~265℃ from the feed end to the extrusion die, and the linear speed of the extrusion process is about 12m / min. Step 8. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer coated in Step 7 has cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain the sheath layer; This provides us with finished cables that are resistant to high voltage, low corona, lightweight, highly flexible, and resistant to high and low temperatures, suitable for the power systems of pure electric aircraft equipment in the low-altitude field.

[0062] Example 5 The present invention relates to a power transmission cable for a power system of pure electric aircraft equipment in the low-altitude field, which has a flexible conductor and, from the inside out, a uniform electric field inner layer, a high-voltage insulation layer, a uniform electric field outer layer, a grounding shield layer, and a sheath layer that are sequentially wrapped around the flexible conductor.

[0063] Specifically, the plated soft copper wire of the flexible conductor has a circular cross-section, and the plating is a tin-plated layer. Depending on the magnitude of the current transmitted and the number of plated soft copper wires, the diameter of a single wire is 0.28 mm. The multiple plated soft copper wires that make up the flexible conductor are arranged concentrically, typically increasing by six wires layer by layer after the central wire, for example, 19 wires. These plated soft copper wires are formed by concentric stranding, with a stranding pitch ratio of approximately 11. The stranded structure is compressed, with a compression factor of approximately 11%, meaning the flexible conductor is a concentrically stranded and compressed structure of multiple plated soft copper wires.

[0064] The uniform electric field inner layer is a polyimide-aluminum composite tape overlapping and wrapping structure on the outside of the flexible conductor. The polyimide-aluminum composite tape is a composite structure of a conductive aluminum foil layer and an insulating polyimide substrate layer, forming a "conductive-insulating" composite structure. It possesses characteristics of high temperature resistance, aging resistance, electrical corrosion resistance, and corona resistance. When it is overlapped and wrapped around the outside of the flexible conductor to form the uniform electric field inner layer, the aluminum foil layer of the polyimide-aluminum composite tape faces inward and is tightly adhered to the surface of the flexible conductor, effectively eliminating electric field concentration caused by burrs and sharp edges on the flexible conductor surface. The aforementioned polyimide-aluminum composite tape constituting the uniform electric field inner layer has a nominal thickness of 0.05 mm and a width not less than the circumference of the flexible conductor. Its overlap rate on the outside of the flexible conductor is 50%. This overlap rate effectively eliminates butt joint gaps, ensuring surface flatness and eliminating porosity from corona discharge.

[0065] The high-voltage insulation layer is an extrusion structure of flexible cross-linked ethylene-tetrafluoroethylene copolymer (XETFE) on the outside of the uniform electric field inner layer. The nominal thickness of the extrusion is about 0.35 mm and the concentricity is about 90%.

[0066] The uniform electric field outer layer is a polyimide aluminum-plastic tape overlapping and wrapping structure outside the high-voltage insulation layer. As mentioned above, the polyimide aluminum-plastic tape is a composite structure of a conductive aluminum foil layer and an insulating polyimide substrate layer. When it is overlapped and wrapped outside the high-voltage insulation layer to form the uniform electric field outer layer, it needs to be used in conjunction with an external grounding shielding layer. Therefore, the aluminum foil layer of the polyimide aluminum-plastic tape faces outward. The aforementioned polyimide aluminum-plastic tape constituting the uniform electric field outer layer has a nominal thickness of 0.05 mm and a width not less than the perimeter of the high-voltage insulation layer. Its overlap rate outside the high-voltage insulation layer is 50%. The overlapping and wrapping structure formed by this overlap rate can effectively eliminate butt joint gaps, ensure surface flatness, and eliminate porosity for corona escape.

[0067] The grounding shielding layer is a braided structure of plated soft copper wire outside the uniform electric field outer layer. The plated soft copper wire of the grounding shielding layer has a circular cross-section structure, and the plating of the plated soft copper wire is a tin-plated structure. The diameter of the single wire of the plated soft copper wire is 0.06mm. Its braiding coverage density outside the uniform electric field outer layer is about 85%, the braiding angle is about 55°, and it forms a tight fit with the aluminum foil layer of the inner uniform electric field outer layer.

[0068] The sheath layer is an extruded structure of flexible cross-linked ethylene-tetrafluoroethylene copolymer (XETFE) outside the grounding shield layer. The nominal thickness of the extrusion is about 0.35 mm and the concentricity is about 90%.

[0069] The cable with the above structure is prepared by the following process steps: Step 1. According to the design specifications, twist multiple coated soft copper wires into a bundle with the twisting pitch ratio set above and in a concentric structure. During the stranding process, the stranded bundle structure is compressed using the aforementioned compression coefficient to obtain a flexible conductor; Step 2. Using polyimide aluminum-plastic tape with a nominal thickness of 0.05 mm and a width not less than the circumference of the flexible conductor, according to the above-set seam overlap rate, the aluminum foil layer is wrapped around the outer surface of the flexible conductor with the aluminum foil layer facing inward and in close contact with the surface of the flexible conductor to obtain a uniform electric field inner layer. Step 3. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. According to the nominal thickness and concentricity set above, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated on the outer surface of the electric field uniform inner layer. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature is in the range of 255℃~265℃ from the feed end to the extrusion die, and the linear speed of the extrusion process is about 18m / min. Step 4. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer to be coated is cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain a high-voltage insulating layer; Step 5. Using polyimide aluminum-plastic tape with a nominal thickness of 0.05 mm and a width not less than the perimeter of the high-voltage insulation layer, wrap it around the outer surface of the high-voltage insulation layer with the aluminum foil layer facing outwards, according to the seam overlap rate set above, to obtain a uniform electric field outer layer. Step 6. Select the corresponding plated soft copper wire according to the above specifications; A braided net is woven on the outer surface of the uniform electric field layer using a braiding machine, and a grounding shielding layer is then covered on the outer surface of the uniform electric field layer. Step 7. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. According to the nominal thickness and concentricity set above, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated on the outer surface of the grounding shield layer. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature is in the range of 255℃~265℃ from the feed end to the extrusion die, and the linear speed of the extrusion process is about 18m / min. Step 8. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer coated in Step 7 has cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain the sheath layer; This provides us with finished cables that are resistant to high voltage, low corona, lightweight, highly flexible, and resistant to high and low temperatures, suitable for the power systems of pure electric aircraft equipment in the low-altitude field.

[0070] The above embodiments are only used to illustrate the present invention and are not intended to limit it.

[0071] Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions of the above embodiments, or equivalent substitutions can be made to some of the technical features. For example, depending on the magnitude of the current transmitted by the electrical energy and the number of plated soft copper wires, the diameter of the single wire of the plated soft copper wire of the flexible conductor can be selected from any of 0.20mm, 0.26mm, 0.32mm, 0.36mm or 0.40mm, etc.; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the present invention.

Claims

1. A high-voltage flexible cable for aviation power supply, characterized in that: The cable has a flexible conductor (1) and, from the inside out, a uniform electric field inner layer (2), a high voltage insulation layer (3), a uniform electric field outer layer (4), a grounding shield layer (5), and a sheath layer (6) that are sequentially wrapped around the flexible conductor (1). The flexible conductor (1) is a structure consisting of multiple coated soft copper wires twisted together and pressed together. The uniform electric field inner layer (2) is an overlapping wrapping structure of polyimide aluminum-plastic tape outside the flexible conductor (1), and the aluminum foil layer of the polyimide aluminum-plastic tape overlapping and wrapping outside the flexible conductor (1) faces inward and is closely attached to the flexible conductor (1). The uniform electric field outer layer (4) is an overlapping wrapping structure of polyimide aluminum-plastic tape outside the high voltage insulation layer (3), and the aluminum foil layer of the polyimide aluminum-plastic tape overlapping and wrapping outside the high voltage insulation layer (3) faces outward. The grounding shield layer (5) is a braided structure of plated soft copper wire outside the uniform electric field outer layer (4), and the grounding shield layer (5) is closely attached to the aluminum foil layer of the uniform electric field outer layer (4) it covers.

2. The high-voltage flexible cable for aviation power supply according to claim 1, characterized in that: The flexible conductor (1) has a circular cross-section structure with a plated soft copper wire, and the plated soft copper wire has a tin plating structure, a silver plating structure, or a nickel plating structure.

3. The high-voltage flexible cable for aviation power supply according to claim 1 or 2, characterized in that: The diameter of the single wire of the plated soft copper wire of the flexible conductor (1) is any one of 0.10mm, 0.12mm, 0.15mm, 0.20mm, 0.26mm, 0.28mm, 0.32mm, 0.36mm, 0.40mm or 0.45mm; The multiple coated soft copper wires that make up the flexible conductor (1) are concentrically stranded with a pitch ratio of 10 to 12 times, and the compression coefficient after stranding is 8% to 12%.

4. The high-voltage flexible cable for aviation power supply according to claim 1, characterized in that: The nominal thickness of the polyimide aluminum-plastic tape of the uniform electric field inner layer (2) is 0.05 mm, and the width is ≥ the perimeter of the flexible conductor (1); The polyimide aluminum-plastic tape that makes up the uniform electric field inner layer (2) is wrapped around the outside of the flexible conductor (1) with a 50% or 66.66% overlap rate.

5. The high-voltage flexible cable for aviation power supply according to claim 1, characterized in that: The high-voltage insulating layer (3) is an extrusion structure of a flexible cross-linked ethylene-tetrafluoroethylene copolymer outside the uniform electric field inner layer (2), with a nominal extrusion thickness of 0.25mm to 0.35mm and a concentricity of ≥90%.

6. The high-voltage flexible cable for aviation power supply according to claim 1, characterized in that: The nominal thickness of the polyimide aluminum-plastic tape of the uniform electric field outer layer (4) is 0.05 mm, and the width is greater than or equal to the perimeter of the high voltage insulation layer (3); The polyimide aluminum-plastic tape that makes up the uniform electric field outer layer (4) is wrapped around the outside of the high voltage insulation layer (3) with a 50% or 66.66% overlap rate.

7. The high-voltage flexible cable for aviation power supply according to claim 1, characterized in that: The grounding shield layer (5) has a circular cross-section structure with a plated soft copper wire, and the plated soft copper wire has a tin plating structure, a silver plating structure, or a nickel plating structure.

8. The high-voltage flexible cable for aviation power supply according to claim 1 or 7, characterized in that: The diameter of the single wire of the plated soft copper wire in the grounding shield layer (5) is 0.06 mm, and the braiding coverage density outside the uniform electric field outer layer (4) is ≥85%, and the braiding angle is 50°~70°.

9. The high-voltage flexible cable for aviation power supply according to claim 1, characterized in that: The sheath layer (6) is an extruded structure of flexible cross-linked ethylene-tetrafluoroethylene copolymer outside the grounding shield layer (5), with a nominal thickness of 0.25mm to 0.35mm and a concentricity of ≥90%.

10. A method for preparing a high-voltage flexible cable for aviation power supply according to any one of claims 1 to 9, characterized in that, The preparation method includes the following process steps: Step 1. According to the design specifications, twist multiple coated soft copper wires into a bundle in a concentric structure, with the twisting pitch ratio controlled at 10 to 12 times; During the stranding process, the stranded bundle structure is compressed to achieve a compression coefficient of 8% to 12%, thereby obtaining a flexible conductor. Step 2. Using polyimide aluminum-plastic tape with a nominal thickness of 0.05 mm and a width not less than the circumference of the flexible conductor, wrap it around the outer surface of the flexible conductor with the aluminum foil layer facing inward and in close contact with the flexible conductor to obtain a uniform electric field inner layer. Step 3. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is heated and plasticized using an extruder. The plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated onto the outer surface of the inner layer with a uniform electric field, according to the nominal thickness of 0.25mm to 0.35mm and the concentricity of not less than 90%. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature from the feed end to the extrusion die is 255℃~265℃, and the linear speed of the extrusion process is 10 m / min~20 m / min. Step 4. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer to be coated is cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain a high-voltage insulating layer; Step 5. Use polyimide aluminum-plastic tape with a nominal thickness of 0.05mm and a width not less than the perimeter of the high-voltage insulation layer, and wrap it around the outer surface of the high-voltage insulation layer with the aluminum foil layer facing outward, according to a 50% or 66.66% overlap rate, to obtain a uniform electric field outer layer. Step 6. Select a plated soft copper wire with a nominal diameter of 0.06mm; A grounding shield layer is covered on the outer surface of the uniform electric field outer layer in the form of a woven mesh, with a woven coverage density of ≥85% and a weaving angle of 50°~70°. Step 7. Use an extruder to heat and plasticize the flexible cross-linked ethylene-tetrafluoroethylene copolymer. With a nominal thickness of not less than 0.20 mm and a concentricity of not less than 90%, the plasticized flexible cross-linked ethylene-tetrafluoroethylene copolymer is uniformly extruded and coated onto the outer surface of the grounding shield layer. The flexible cross-linked ethylene-tetrafluoroethylene copolymer is extruded and coated in the form of a tube extrusion. The tensile coefficient DDR of the extrusion die is 20, the die matching coefficient DBR is 1.2, the heating and plasticizing temperature from the feed end to the extrusion die is 255℃~265℃, and the linear speed of the extrusion process is 10m / min~20m / min. Step 8. After the flexible cross-linked ethylene-tetrafluoroethylene copolymer coated in Step 7 has cooled, it is irradiated and cross-linked modified by high-energy electron beam to obtain the sheath layer; This resulted in the production of high-voltage, flexible finished cables for aviation power supplies.

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