A torsion-resistant electric vehicle charging cable and a method of manufacturing the same

Abstract

The application relates to the technical field of electric wire and cable, and particularly discloses a torsion-resistant electric vehicle charging cable and a preparation method thereof. The torsion-resistant electric vehicle charging cable comprises a signal unit group which is twisted by a ground wire core, a shielded signal core, a non-shielded signal core group and two auxiliary power supply wires, the outside of the signal unit group is wrapped with an isolation belt, and the outside of the isolation belt is extruded and wrapped with a nylon inner lining layer; a cable core main body which is twisted by a plurality of main wire cores, the signal unit group, a center filling piece and a side filling piece; a center support structure is arranged at the center position of the conductor of each main wire core, the ground wire core, the shielded signal core, the non-shielded signal core and the auxiliary power supply wire; a glue solidification filling body; a reinforced non-woven fabric; a fiber braiding layer; and a sheath. The application has the advantages of improving the torsion resistance, structural stability and service life of the electric vehicle charging cable, and solving the problems of easy shrinkage of the conductor, non-circularity of the cable core and easy damage of the sheath in the existing products.

Description

Technical Field

[0001] This application relates to the field of wire and cable technology, and more specifically, to a torsion-resistant electric vehicle charging cable and a method for preparing the same. Background Technology

[0002] With the booming development of the new energy vehicle industry and the increasing popularity of electric vehicles, the requirements for charging infrastructure, especially charging cables, are constantly rising. Existing electric vehicle charging cables need to withstand frequent bending, dragging, and twisting during use. Especially for high-frequency usage scenarios such as logistics and express delivery, the torsion conditions of charging cables are extremely harsh.

[0003] Currently, several structural design solutions have been developed to improve the torsional resistance of cables, such as adding irregularly shaped fillers in the center of the cable core or extruding an insulation layer around the conductor. Their structures are as follows: Figure 1 As shown, however, many shortcomings remain. For example, the conductor is made of multiple stranded copper wires with internal gaps, making it prone to shrinkage or even breakage when twisted; the irregularly shaped filler in the center is difficult to control in terms of size, resulting in difficult processing and low production efficiency; the inner side of the cable sheath is not round enough, making it impossible to use an automatic wire stripper for stripping, increasing assembly difficulty; furthermore, during use, the cable experiences concentrated torque at its contact points with the ground and at the tail of the charging gun, making the sheath prone to twisting, bulging, or even cracking. These problems seriously affect the service life and reliability of the charging cable, causing considerable trouble for cable manufacturers and end users. Summary of the Invention

[0004] To improve the torsion resistance, structural stability, and service life of electric vehicle charging cables, and to solve problems such as conductor shrinkage, non-round core, and easy damage to the sheath in existing products, this application provides a torsion-resistant electric vehicle charging cable and its preparation method.

[0005] In a first aspect, this application provides a torsion-resistant electric vehicle charging cable, which adopts the following technical solution: A torsion-resistant electric vehicle charging cable, comprising: The signal unit group is composed of a ground wire core, a shielded signal core, an unshielded signal core group and two auxiliary power lines twisted together. The signal unit group is wrapped with an isolation strip, and the isolation strip is extruded with a nylon inner lining layer. The cable core body is composed of multiple main cores, signal unit groups, center filler and side filler twisted together. The center filler is located at the center of the cable core body, and the side fillers fill the gaps on the sides of the cable core body. Each main core, ground core, shielded signal core, unshielded signal core and auxiliary power line conductor has a center support structure at its center. The glue-cured filler is used to fill all the gaps inside the cable core body; Reinforced nonwoven fabric is wrapped around the outside of the cable core body; A fiber braided layer is wrapped around the outside of the reinforced nonwoven fabric; The sheath is extruded onto the outside of the fiber braided layer, and the material of the sheath is embedded in the fiber gaps of the fiber braided layer, so that the sheath and the fiber braided layer are fused together as one.

[0006] By adopting the above technical solution, a central support structure is set at the center of each conductor, which effectively limits the shrinkage space of the conductor copper strands under torsional compression, reduces the problem of wire breakage caused by conductor shrinkage, and significantly improves the conductor's torsional and tensile resistance. The cable core body is supported by the central filler and side fillers, combined with the glue-cured filler filling all gaps, forming a highly rounded and displacement-free integral structure. This not only improves the roundness of the cable, facilitating the uniform extrusion and automatic stripping of the sheath, but also ensures that each individual wire inside the cable core is intact during torsion. With fixed positions and shared stress, deformation caused by localized stress concentration is reduced. Meanwhile, the reinforcing non-woven fabric and fiber braided layer wrapped around the outside of the cable core provide a solid adhesion base for the sheath. During extrusion, the molten sheath material is embedded in the gaps of the fiber braided layer. After solidification, the two fuse together to form a composite reinforcing layer of sheath and fiber. This can quickly transfer and disperse the localized torsional force to the entire cable length, effectively avoiding torsion, bulging, and cracking of the sheath caused by torsion concentration. This significantly improves the service life and reliability of the cable under repeated torsion conditions.

[0007] Preferably, the central support structure is made of multiple strands of aramid fibers twisted together and coated with high-temperature resistant elastic adhesive, and the central support structure is made of a non-hygroscopic material; the conductors of the main core and ground core are formed by twisting multiple strands of copper wire with a diameter of 0.193±0.01mm around the central support structure; the conductors of the shielded signal core, unshielded signal core, and auxiliary power line are formed by twisting multiple copper wires with a diameter of 0.15mm around the central support structure, and the cross-section of a single signal core is 0.5mm². 2 The conductor tensile strength is ≥800N.

[0008] By adopting the above technical solution, using aramid fiber strands as the central support of the conductor, it combines high tensile strength and excellent flexibility. Applying adhesive can reduce defects such as air bubbles in the insulation layer caused by moisture absorption, ensuring the stability of signal transmission. By limiting the diameter of the copper wire and the stranding method, the conductor can achieve high flexibility while being tightly integrated with the central support structure, ensuring the structural integrity of the conductor as a whole during the torsion process.

[0009] Preferably, the insulation layers of the main wire core, ground wire core, and auxiliary power line are made of XLPO flame-retardant polymer material; the insulation layers of the shielded signal core and the unshielded signal core are made of high yield strength elastomer material, with a yield strength ≥20MPa, tensile strength ≥25MPa, elongation at break ≥300%, and no shrinkage after stretching.

[0010] By adopting the above technical solution, the main conductor and ground conductor are made of XLPO material to ensure the insulation safety and flame retardancy of the cable under high temperature conditions. The signal core insulation layer is made of a special high yield strength elastomer material, which has the characteristics of high yield strength and no shrinkage after stretching. When the cable is torn, the insulation layer can effectively resist deformation and maintain its original size after the external force is removed. This avoids the risk of bulging or breakage of the signal core due to the insulation layer shrinking and squeezing the internal conductor, and significantly improves the reliability of signal transmission.

[0011] Preferably, the unshielded signal core group is composed of 8 unshielded signal cores twisted together with a twisting pitch ratio of 9, and is wrapped with an isolation strip on the outside; the shielded signal core is composed of two signal cores and a composite shielding layer that covers the two signal cores together. The composite shielding layer includes an aluminum foil layer wrapped around the two signal cores and a tinned copper wire braided layer woven around the aluminum foil layer, with a braiding density of ≥80%; the ground core, shielded signal core, unshielded signal core group and two auxiliary power lines are twisted together to form a signal unit group with a twisting pitch ratio of 10.

[0012] By adopting the above technical solution, the unshielded signal core is first pre-twisted, and then twisted a second time with the shielded signal core, ground core, and auxiliary power line, making the internal structure of the signal unit group compact and stable. The shielded signal core adopts a shielding structure of aluminum foil wrapping and high-density tinned copper wire braiding, which can effectively resist external electromagnetic interference, ensure the accurate transmission of control signals during charging, and improve the stability and safety of charging.

[0013] Preferably, the central filler is a circular high-hardness elastomer, the side fillers are vulcanized rubber strips, and the adhesive-cured filler is a quick-drying adhesive that is elastic after curing.

[0014] By adopting the above technical solutions, the circular filler is easier to control in terms of size, significantly reduces the processing difficulty, and increases production efficiency compared to the irregular filler. The side filler uses vulcanized rubber strips, which provide good elastic support. After the cable core is stranded, an elastic quick-drying adhesive is applied and cured. The adhesive can penetrate and fill all the tiny gaps, bonding all the components inside the cable core into a flexible and strong whole. This effectively avoids the mutual movement and friction between the components during torsion, ensuring the structural stability of the cable during long-term use.

[0015] Preferably, the fiber braided layer is an aramid fiber braided layer with a braiding density of 25-35%; the sheath is made of flame-retardant polyurethane material; and the surface of the sheath is provided with several uniform arc-shaped protrusions.

[0016] By adopting the above technical solution, the aramid fiber braided layer has the characteristics of high strength and low elongation. After being fused with the polyurethane sheath, it can significantly improve the overall tear resistance and torsion resistance of the sheath layer. The uniform arc-shaped raised structure on the surface of the sheath can cover up the surface unevenness that may be caused by the internal fiber braiding, and improve the roundness of the cable appearance. It can also effectively reduce the contact area and friction between the cable and the ground, so that the torque generated during torsion can be transmitted more smoothly along the cable axis, avoiding the concentration of torque at a certain point, and further protecting the sheath.

[0017] Secondly, this application provides a method for manufacturing a torsion-resistant electric vehicle charging cable, employing the following technical solution: A method for preparing a torsion-resistant electric vehicle charging cable includes the following steps: S1. Conductor Preparation: A central support structure is set at the center of the main conductor core and the ground conductor core. Multiple copper wires are twisted into copper strands, and then the multiple copper strands are twisted around the central support structure. The direction of the copper strands is consistent with the direction of the twisting. A nano-coated mold is used for compacting and forming to form the conductive part of each conductor. A central support structure is set at the center of the shielded signal core, the unshielded signal core, and the auxiliary power line conductors. Multiple copper wires are twisted around the central support structure and compacted and formed using a nano-coated mold to form the conductive part of each conductor. S2. Insulation extrusion: XLPO flame-retardant polymer material is extruded over the conductors of the main conductor, ground conductor and auxiliary power line to form an insulation layer; high yield strength elastomer material is extruded over the conductors of the shielded signal core and unshielded signal core to form an insulation layer. S3, Signal Unit Composition Cable: Multiple unshielded signal cores are twisted together to form an unshielded signal core group; aluminum foil and braided tinned copper wire are wrapped around the outside of two signal cores to form a shielded signal core; the ground core, shielded signal core, unshielded signal core group and two auxiliary power lines are twisted together, wrapped with isolation tape and then extruded with a nylon inner lining layer to form a signal unit group; S4. Cable core body: Multiple main wire cores, signal unit groups, center filler and side filler are twisted together to form the cable core body, and the twisted cable core body is shaped. S5. Filling gaps: Impregnate the stranded cable core body with paste-like quick-drying elastic adhesive to fill all gaps inside the cable core body. After scraping off excess adhesive, wrap reinforced non-woven fabric around the outside of the cable core body with the polyester side of the non-woven fabric facing inward. S6. Fiber weaving: An aramid fiber layer is woven into the outer side of the reinforced nonwoven fabric, with a weaving density of 25-35%; S7. Sheath Extrusion: A sheath is extruded over the outside of the aramid fiber layer, so that the molten sheath material is embedded in the fiber gaps of the aramid fiber layer and melts and fuses with the aramid fiber layer as one.

[0018] By adopting the above technical solution, a high-stability cable structure is constructed layer by layer through multiple processes such as introducing central support during conductor stranding, circular filling, glue impregnation and filling gaps, and wrapping reinforcement layers during cabling. Glue impregnation and filling gaps solve the problems of integrity and anti-shrinkage inside the cable core, and the fusion of the aramid braided layer and the sheath solves the problems of uniform stress distribution and crack resistance of the sheath layer. This enables the stable and efficient production of charging cables with excellent torsion resistance, which are suitable for large-scale industrial production.

[0019] Preferably, in step S4, the twisted pitch ratio is ≤16 times, and two pressing dies are used for shaping.

[0020] By adopting the above technical solutions, controlling the stranding pitch ratio and using two pressing dies for shaping, it is possible to ensure that the cable core body is tightly stranded, structurally stable, and has a round outer diameter. This provides precise-sized and regularly shaped semi-finished products for subsequent glue filling and sheath extrusion, which helps to ensure the quality consistency of the final product.

[0021] Preferably, in step S7, the raw material of the sheath is dried to a moisture content of ≤200PPM before extrusion, and the extrusion is carried out using a special mold with an arc-shaped groove at the die outlet.

[0022] By adopting the above technical solution and performing strict drying pretreatment on the polyurethane sheath raw material, defects such as pores and cracks caused by moisture vaporization during the sheath extrusion process can be effectively avoided, ensuring the density and mechanical strength of the sheath layer. The use of a special mold with an arc-shaped groove at the outlet can directly form a uniform arc-shaped protrusion structure on the sheath surface, which not only improves the aesthetics and roundness of the cable, but also effectively reduces friction and promotes torque transmission, thereby further improving the cable's torsional resistance.

[0023] In summary, this application has the following beneficial effects: 1. This application solves the problem of conductor shrinkage and breakage during torsion by setting a tensile support structure made of aramid fiber at the center of each conductor. At the same time, by using circular filling in the center of the cable core and rubber strip filling on the sides, and filling and curing all gaps with elastic glue, the entire cable core becomes a whole without relative displacement, which can jointly bear torsional stress. Combined with the aramid braided reinforcement layer on the outside of the cable core and the sheath, as well as the arc-shaped protrusion structure on the surface of the sheath, the torque is efficiently and uniformly transmitted from the sheath to the cable core, avoiding stress concentration, thereby greatly improving the service life and reliability of the cable under frequent torsion conditions.

[0024] 2. In this application, the signal core insulation layer uses a specially made high-yield-strength, low-retraction elastomer material, which avoids the compression and damage to the signal conductor caused by insulation shrinkage due to torsion, thus ensuring the long-term stability of signal transmission. At the same time, through circular filling, glue filling, and wrapping with reinforced non-woven fabric, the defects of non-round cable core and twisted surface of traditional cable are effectively solved, resulting in extremely high overall roundness of the cable. This not only makes the cable aesthetically pleasing but also facilitates subsequent automated wire stripping processing and improves production efficiency.

[0025] 3. This application uses a circular center filler instead of a difficult-to-process irregularly shaped filler, greatly reducing the control difficulty and scrap rate in the production process and improving the production efficiency of the stranding process. At the same time, the glue impregnation and fusion processes of the aramid braided layer and sheath can both be achieved on existing production lines with simple modifications, demonstrating strong process adaptability. The resulting cable exhibits superior performance, effectively solving many pain points in the processing and use of existing products, and possessing good market application prospects and economic value. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structural cross-section of an existing cable in the background art.

[0027] Figure 2 This is a schematic diagram of the conductor and central support structure of this application.

[0028] Figure 3 This is a schematic diagram of the signal unit group in this application.

[0029] Figure 4 This is a structural schematic diagram of the finished cable of this application.

[0030] Figure 5 This is a stress-strain curve of the insulating layer of the signal core in this application.

[0031] Figure 6 This is a stress-strain curve of the ordinary insulating layer in this application.

[0032] Explanation of reference numerals in the attached diagram: 1. Central support structure; 11. Aramid fiber; 12. Copper strand; 2. Main core; 3. Signal unit group; 31. Ground core; 32. Shielded signal core; 33. Unshielded signal core group; 35. Auxiliary power line; 36. Isolation strip; 37. Nylon inner lining layer; 4. Cable core body; 5. Reinforced non-woven fabric; 6. Fiber braided layer; 7. Adhesive-cured filler; 8. Sheath; 9. Central filler; 10. Side filler. Detailed Implementation

[0033] The following is in conjunction with the appendix Figure 1-6 The present application will be further described in detail with reference to the embodiments.

[0034] The raw materials used in the preparation examples, embodiments, and comparative examples of this application are from the following sources: The aramid fiber used in the central support structure was purchased from Taihe New Materials Group Co., Ltd., with a specification of 1100 Dtex aramid. The quick-drying adhesive was purchased from Dongguan Dongxin Electronics Technology Co., Ltd., SC730 single-component RTV adhesive. XLPO flame-retardant polymer material was purchased from Suzhou Meiyu Polymer Materials Co., Ltd., grade: MG80019S; The high yield strength elastomer material was purchased from Suzhou Tongyou New Material Technology Co., Ltd., grade: TY-105J; The nylon material was purchased from Wanhua Chemical, specifically Nylon 12. The aramid fiber used in the fiber braiding layer was purchased from DuPont, specification: 1580 Dtex aramid. The high-hardness elastomer used for the center filler was purchased from Suzhou Meiyu Polymer Materials Co., Ltd., grade: MG80019S. The center was made of cotton thread, which was extruded and then cross-linked by irradiation using an electron accelerator to form the filler. The vulcanized rubber strips were purchased from Mafu Rubber & Plastics (Zhenjiang) Co., Ltd. The high-hardness, fast-curing 90℃ ethylene propylene general-purpose insulating material IE4 was extruded using a continuous vulcanizing extruder at an extrusion temperature of 50-100℃. After extrusion, saturated steam vulcanization was performed at a temperature of 180-200℃ and a steam pressure of approximately 10-13 kg, with a production speed of 20-30 minutes. The reinforced nonwoven fabric was purchased from Jiangyin Bailai Cable Materials Co., Ltd., with a thickness of 0.16mm and a width of 50mm. Flame-retardant polyurethane sheath material was purchased from BASF 1185A10WDM; The irregularly shaped filler was purchased from Mafu Rubber & Plastics (Zhenjiang) Co., Ltd. It is a high-hardness, fast-curing 90℃ ethylene propylene general-purpose insulating material IE4. It is extruded using a continuous vulcanizing extruder at an extrusion temperature of 50-100℃. After extrusion, it is vulcanized by saturated steam at a temperature of 180-200℃ and a steam pressure of about 10-13kg. The production speed is 20-30min. Polypropylene rope purchased from Wuxi Henglong; high temperature resistant twisted PP rope, specifications 1.1, 1.6, 2.2, 2.6, 3.0, 3.5, 4.0mm; The PVC sheath material was purchased from Changshu Zhonglian, H90 or HZ90. Examples of Central Support Structure Fabrication 1-2

[0035] Preparation Example 1 The preparation method of the central support structure is as follows: Aramid fibers are twisted at a pitch ratio of 15 times at a speed not exceeding 100m / min. After twisting, the fibers are passed through an iron trough filled with glue. The iron trough has multiple guide rollers and is 100m long. The glue in the iron trough is obtained by blending chloroprene latex, butyl rubber latex, resorcinol-formaldehyde resin, and resorcinol in a mass ratio of 0.1:0.1:0.6:0.1. The iron trough is equipped with heating and cooling devices to ensure that the glue temperature is controlled between 35-40℃. The aramid fibers after being impregnated with glue are baked and dried in an oven at a temperature between 80-100℃. After baking, they are cooled by air cooling and wound up using special equipment.

[0036] Preparation Example 2 The difference between Preparation Example 2 and Preparation Example 1 is that the aramid fibers are twisted at a pitch ratio of 18 times at a speed not exceeding 100 m / min. After twisting, they are passed through an iron trough filled with glue. The iron trough has multiple guide rollers and is 100 m long. The glue in the iron trough is a blend of chloroprene latex, butyl rubber latex, resorcinol-formaldehyde resin, and resorcinol in a mass ratio of 0.2:0.2:0.8:0.2. The iron trough is equipped with heating and cooling devices to ensure that the glue temperature is controlled between 35-40°C. The aramid fibers after being impregnated with glue are baked and dried in an oven at a temperature between 80-100°C. After baking, they are cooled by air cooling and wound up using special equipment. Example

[0037] Example 1 A method for preparing a torsion-resistant electric vehicle charging cable includes the following steps: S1. Conductor Preparation: Reference Figure 2 and Figure 3 The central support structure 11 prepared in Preparation Example 1 is used and is respectively set at the center of the conductors of the main wire core 2, ground wire core 31, shielded signal core 32, and unshielded signal core. The conductors of the main wire core 2 and the ground wire core 31 are made of copper wire with a diameter of 0.193 mm. First, multiple copper wires are bundled together to form copper wire strands 12, and then the multiple copper wire strands 12 are twisted around the central support structure 1. The bundle direction and the twisting direction of the copper wire strands 12 are both to the left. The conductor cross-section of the main wire core 2 is 35 mm². 2 The cross-section of conductor 31 in the ground wire core is 6mm². 2The conductors of the shielded signal core 32, the unshielded signal core, and the auxiliary power line 35 are made of copper wire with a diameter of 0.15mm. Multiple copper wires are twisted together around the central support structure 1. The cross-section of a single signal core is 0.5mm². 2 The auxiliary power cord has a cross-section of 1.5mm². 2 After stranding, a nano-coated mold is used for compacting to make the conductor surface smooth and compact.

[0038] S2. Insulation Extrusion: XLPO flame-retardant polymer material is extruded over the conductors of the main conductor 2, ground conductor 31, and auxiliary power line 35. The extrusion temperature is set according to Table 1 to form an insulation layer. The nominal insulation thickness of the main conductor 2 is 0.9 mm, the nominal insulation thickness of the ground conductor 31 is 0.7 mm, and the nominal insulation thickness of the auxiliary power line 35 is 0.7 mm. High yield strength elastomer material is extruded over the conductors of the shielded signal core 32 and the unshielded signal core. The extrusion temperature is set according to Table 2 to form an insulation layer with a nominal insulation thickness of 0.5 mm.

[0039] S3, Signal Unit Composition Cable: Reference Figure 2 and Figure 3 Eight unshielded signal cores are twisted together at a twist ratio of 9, and then wrapped with a layer of polyester insulating tape 36 to form an unshielded signal core group 33. An aluminum foil layer is wrapped around two signal cores in sequence, with an overlap rate of ≥25%. Tinned copper wire is then braided around the aluminum foil at a braiding density of 85% to form a shielded signal core 32. One ground core 31, one shielded signal core group 32, one unshielded signal core group 33, and two 1.5mm² cross-section wires are then combined. 2 The auxiliary power lines 35 are twisted together with a twisting pitch ratio of 10. After wrapping a layer of isolation tape 36, a layer of nylon material with a thickness of 0.1mm is extruded on the outside of the isolation tape 36 as a nylon inner lining layer 37 to form the signal unit group 3.

[0040] S4, Cable Core Body: Reference Figure 3 The four main conductor cores 2, one signal unit group 3, one center filler 9, and four side fillers 10 are twisted together. The center filler 9 is a circular high-hardness elastomer, and the side fillers 10 are vulcanized rubber strips. The twisting pitch ratio is 14 times. The cable core 4 is shaped using two compression dies to form the cable core 4.

[0041] S5. Filling gaps: Reference Figure 3 The stranded cable core 4 is passed through an adhesive impregnation device at a speed of 1.5 m / min. The device contains a paste-like quick-drying elastic adhesive, which fills all the gaps inside the cable core body 4. Then, the cable core 4 is passed through an adhesive scraping mold to remove excess adhesive. After scraping, a reinforcing non-woven fabric 5 is wrapped around the outside of the cable core body 4 with an overlap rate of 25% and the polyester side of the non-woven fabric facing inward.

[0042] S6, Fiber Weaving: Reference Figure 3 A fiber braided layer 6 is woven on the outside of the reinforced nonwoven fabric 5, with a braiding density of 30%.

[0043] S7, Sheath 8 Extrusion: Flame-retardant polyurethane sheath material is extruded onto the outside of the fiber braided layer 6. Before extrusion, the sheath material is dried at 90℃ for 4 hours until the moisture content is ≤200PPM. Extrusion is performed using a special mold with an arc-shaped groove at the die outlet. The die aperture is consistent with the maximum outer diameter of the cable. After extrusion, the nominal thickness of sheath 8 is 2.4mm, and a uniform arc-shaped raised structure is formed on the surface of sheath 8. The extrusion temperature is set according to Table 3 to obtain the finished cable.

[0044] Example 2

[0045] The difference between Example 2 and Example 1 is that in S1, the diameter of the copper wire is 0.183 mm and the average thickness of the insulation of the main core is 1.0 mm.

[0046] In S4, the twist pitch ratio is 16, the center filler diameter is 8.5mm, and the side filler diameter is 4.0mm.

[0047] In S5, the cable core passes through the glue impregnation device at a speed of 1.0 m / min, and the overlap rate of the reinforcing nonwoven fabric is 30%.

[0048] In S6, the weaving density is 25%.

[0049] In S7, the sheath material is dried at 85℃ for 5 hours, and the nominal thickness of the sheath is 2.6mm.

[0050] Example 3

[0051] The difference between Example 3 and Example 1 is that in S1, the diameter of the copper wire of the main conductor is 0.203 mm.

[0052] Example 4

[0053] The difference between Example 4 and Example 1 is that in S4, the central filler is an irregularly shaped filler with a star-shaped cross-section that matches the central gap of the cable core and is made of vulcanized rubber. The side fillers are polypropylene ropes and no glue is used for gap filling.

[0054] Example 5

[0055] The difference between Example 5 and Example 1 is that in S6, the weaving density is 15%.

[0056] Example 6

[0057] The difference between Example 6 and Example 1 is that in S6, the weaving density is 45%.

[0058] Example 7

[0059] The difference between Example 7 and Example 1 is that in S5, the cable core body is not impregnated with glue, but directly wrapped with reinforcing non-woven fabric.

[0060] Example 8

[0061] The difference between Example 8 and Example 1 is that in S7, a common die is used when extruding the sheath, that is, there is no arc groove design at the die outlet and the surface of the sheath is a smooth plane.

[0062] Example 9

[0063] The difference between Example 9 and Example 1 is that in S1, no central support structure is provided at the center of the conductor, that is, the central support structure is omitted, and the conductor is formed by conventionally twisting together multiple copper wires.

[0064] Table 1 Extrusion Temperature of XLPO Flame Retardant Polymer Materials Temperature (±5℃) 155 165 175 185 185 190 190 Table 2 Extrusion Temperatures of High Yield Strength Elastomer Materials Temperature (±5℃) 200 220 230 240 250 260 260 Table 3 Extrusion Temperature of Sheath Temperature (±5℃) 155 165 180 185 190 185 180 170 170 90 -40 Comparative Example

[0065] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that in Comparative Example 1, the conductor adopts a conventional Class 6 conductor structure, that is, a structure without a central support, the center of the cable core adopts an irregularly shaped filler made of vulcanized rubber, the sides of the cable core are not filled, the cable core is not subjected to glue impregnation and gap filling treatment after stranding, the outer side of the cable core is not provided with an aramid braided layer, and the sheath is extruded from ordinary polyvinyl chloride material.

[0066] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that in Comparative Example 2, the signal core insulation layer uses conventional XLPO material, which is the same as the main core insulation material, rather than a high-yield elastomer material.

[0067] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that in Comparative Example 3, the central filler is an irregularly shaped filler, the side fillers are polypropylene ropes, and no glue impregnation and filling treatment is performed. Performance testing

[0068] I. Torsion-resistant electric vehicle charging cables were prepared according to the preparation methods of Examples 1-9 and Comparative Examples 1-3. The finished cables were subjected to the following performance tests, and the results are recorded in Table 4.

[0069] Torsion Test: The torsion test shall be conducted according to the torsion test method described in the instruction manual. Specifically, after assembling the cable with the charging gun, under room temperature conditions, the charging gun line shall operate at the maximum normal operating current. One end of the cable shall be moved back and forth at a height of 1.2m above the ground. The total length of the cable is 5m, the torsion frequency is 1m / turn, and the total travel distance is 3m. The outward torsion is clockwise, and the return torsion is counterclockwise. Record the number of torsions that occur when the cable bulges, cracks, or signal core breaks. The result is expressed in "times," and the larger the value, the better the torsion resistance.

[0070] Conductor tensile strength test: The tensile strength of the signal core conductor shall be tested in accordance with the method specified in GB / T 3956-2008 "Conductors of Cables".

[0071] Sheath peel force test: Refer to the sheath peel force test method specified in GB / T 2951.11-2008 "General Test Methods for Insulation and Sheath Materials of Cables and Optical Cables" to peel the sheath of the finished cable and record the peel force. The result is represented by "N". The smaller the value, the easier it is to peel the sheath.

[0072] Cable core roundness test: Using a vernier caliper with an accuracy of 0.01mm, measure the outer diameter at 6 points evenly on the same cross-section of the finished cable, and calculate the difference between the maximum and minimum values. The smaller the difference, the higher the cable core roundness.

[0073] Sheath surface appearance inspection: Visually inspect the surface of the finished cable sheath for obvious strands, pits or other appearance defects.

[0074] Table 4 Cable Performance Testing Example 1 18600 835 28 0.15 Round and smooth, without twisting. Example 2 17200 812 31 0.18 Round and smooth, without twisting. Example 3 15800 806 32 0.21 Round and smooth, without twisting. Example 4 9200 823 65 0.52 The surface has obvious twisted texture Example 5 12300 819 42 0.23 Round and smooth, without twisting. Example 6 13200 827 35 0.25 Round and smooth, without twisting. Example 7 8400 818 39 0.35 Round and smooth, without twisting. Example 8 13800 831 33 0.22 Smooth surface, without any protruding structures Example 9 7600 415 38 0.38 Round and smooth, without twisting. Comparative Example 1 3200 386 72 0.87 The surface has obvious striations and pits. Comparative Example 2 12400 426 35 0.28 Round and smooth, without twisting. Comparative Example 3 5600 819 58 0.61 The surface has obvious twisted texture As can be seen from Table 4, Examples 1-3 and Comparative Example 1, the torsion-resistant electric vehicle charging cables prepared in Examples 1-3 have excellent torsion resistance, with a torsion resistance of over 15,800 cycles. They also exhibit high conductor tensile strength, low sheath peel force, high core roundness, and a smooth, round sheath surface without twisting. Comparative Example 1, which uses a conventional conductor structure without central support, shaped polypropylene filling, no glue gap filling, no aramid braided layer, and a sheath made of ordinary polyvinyl chloride, has a torsion resistance of only 3,200 cycles, a conductor tensile strength of only 386 N, a sheath peel force as high as 72 N, a maximum difference in core outer diameter of 0.87 mm, and obvious twisting and pitting on the surface.

[0075] This demonstrates that by setting a central support structure at the center of each conductor, composed of stranded aramid fibers coated with high-temperature resistant elastic adhesive, this application effectively limits the contraction space of the copper wire strands during torsion, avoiding wire breakage caused by compression and contraction, and significantly improving the tensile strength and torsional resistance of the conductor. Simultaneously, the synergistic support of the circular central filler and side fillers, combined with the overall structure formed by filling all gaps inside the cable core with elastic adhesive-cured filler, effectively eliminates voids and relative displacement within the cable core, ensuring that each unit works together during torsion. Under stress and with overall deformation, local stress concentration is avoided, thus significantly improving the torsion resistance. In addition, the aramid fiber braided layer on the cable core surface is integrated with the melt-extruded polyurethane sheath to form a sheath-fiber composite reinforcement layer, which can quickly transfer and disperse local torque to the entire cable length. Combined with the arc-shaped protrusion structure on the sheath surface to reduce friction and promote torque transmission, it effectively avoids sheath torsion, bulging and cracking. At the same time, it improves the roundness of the cable core and reduces the sheath peeling force, making the cable easy to process in automated stripping and with excellent long-term reliability.

[0076] Compared with Example 1, Example 4 showed a decrease in the number of torsion cycles from 18,600 to 9,200, an increase in sheath peel force from 28N to 65N, an increase in the maximum difference in outer diameter from 0.15mm to 0.52mm, and obvious twisting marks on the sheath surface. Example 4 changed the center filler to a shaped filler and the side filler to polypropylene rope, and did not use glue for gap filling. This indicates that the shaped filler is difficult to control in terms of direction and size during production, which makes it difficult to effectively fill the internal gaps when the cable core is twisted. The core units are prone to relative displacement and shrinkage during torsion, thus reducing the torsion resistance. In addition, the roundness of the cable core deteriorates, causing the sheath material to embed into the gaps on the surface of the cable core during extrusion, resulting in difficulty in sheath peeling and the appearance of twisting marks on the surface.

[0077] Compared to Example 1, Examples 5 and 6 exhibited 12,300 and 13,200 cycles of torsion resistance, respectively, both lower than Example 1's 18,600 cycles. The aramid weaving density in Example 5 was 15%, and in Example 6 it was 45%. This indicates that when the aramid weaving density is too low, the reinforcing effect of the weaving layer on the sheath is insufficient, and the torque cannot be effectively transmitted and dispersed, resulting in localized stress concentration in the sheath. Conversely, when the weaving density is too high, the gaps between the fibers are too small, making it difficult for the molten sheath material to fully embed into the fiber gaps and fuse with the weaving layer during extrusion. This weakens the bond strength between the sheath and the weaving layer, leading to a decrease in the reinforcing effect. Therefore, controlling the weaving density ensures that the sheath material is fully embedded in the fiber gaps to form a strong fusion while providing sufficient reinforcement, thus achieving optimal torsion resistance.

[0078] Compared to Example 1, Example 7 showed a significant decrease in the number of torsion cycles from 18,600 to 8,400, and an increase in the maximum difference in outer diameter from 0.15 mm to 0.35 mm. In Example 7, the cable cores were directly wrapped with reinforcing non-woven fabric without adhesive impregnation after stranding. This indicates that the cable core without adhesive impregnation has a large number of voids, lacking fixation and support between the core units. During torsion, the cores are prone to shifting and shrinking, leading to cable core structural instability, decreased roundness, and a significant reduction in torsion resistance.

[0079] Compared with Example 1, Example 8 has a torsion resistance of 13,800 cycles, which is lower than the 18,600 cycles of Example 1. Moreover, the sheath surface is a smooth plane without any arc-shaped protrusions. Example 8 uses a common die during the extrusion of the sheath, and there is no arc-shaped groove design at the die exit. This indicates that the arc-shaped protrusions on the sheath surface can not only cover up the surface unevenness that may be caused by the internal fiber weaving, but more importantly, it can effectively reduce the contact area and friction between the cable and the ground, so that the torque generated during torsion can be transmitted more smoothly along the cable axis, avoiding the concentration of torque at the charging gun tail and ground contact point, thereby further improving the torsion resistance.

[0080] Compared with Example 1, Example 9 showed a sharp decrease in the number of torsion cycles from 18,600 to 7,600, a significant decrease in the conductor tensile strength from 835N to 415N, and an increase in the maximum difference in outer diameter to 0.38mm. Example 9 did not have a central support structure at the center of the conductor and used a conventional method of stranding multiple copper wires together to form the conductor. This indicates that during the torsion process, when the torsion direction is the same as the conductor stranding direction, compression and contraction will occur inside the conductor copper wire strands. The conductor without a central support structure cannot effectively resist this contraction, which can easily lead to overall conductor shortening and copper wire breakage. At the same time, the instability of the conductor's outer diameter also affects the overall roundness of the cable core.

[0081] Compared with Example 1, Comparative Example 2 has a torsion resistance of 12,400 cycles, which is lower than the 18,600 cycles of Example 1. The conductor tensile strength is 426 N, which is much lower than the 835 N of Example 1. In Comparative Example 2, the signal core insulation layer uses conventional XLPO material instead of the high yield strength elastomer material of this application. This shows that conventional XLPO insulation material has insufficient yield strength when subjected to torsional tension and is prone to shrinkage after stretching. The shrinkage of the insulation layer will squeeze the internal signal conductor, causing the signal core to bulge or even break. At the same time, the stress generated by the shrinkage will also cause additional damage to the conductor, reducing the effective tensile strength of the conductor. In contrast, the high yield strength elastomer material used in this application has a yield strength ≥20 MPa, a breaking force ≥25 MPa, and no shrinkage after stretching. It can effectively resist deformation and maintain its original size during torsion, avoiding compression damage to the internal conductor, thereby ensuring the long-term stability of the signal core and the overall torsion resistance of the cable.

[0082] Compared with Example 1, Comparative Example 3 had a torsion resistance of 5600 cycles, which is much lower than the 18600 cycles of Example 1. The sheath peel force was 58N, which is higher than the 28N of Example 1. The maximum difference in outer diameter was 0.61mm and there were obvious twisted patterns on the surface. Comparative Example 3 used irregularly shaped fillers and polypropylene ropes as side fillers and did not perform glue impregnation and gap filling treatment. This shows that irregularly shaped fillers combined with non-elastic polypropylene ropes cannot provide effective elastic support and buffering during torsion. At the same time, there are a lot of voids inside the unfilled cable core. Each core unit undergoes significant relative displacement and contraction during torsion, resulting in a loose cable core structure and extremely poor roundness. After extruding the sheath, the sheath is embedded in the gaps on the surface of the cable core, making peeling difficult and severely reducing the torsion resistance.

[0083] II. Insulation performance testing of main conductor, ground conductor and signal conductor 1. Insulation performance testing of main conductor and ground conductor Sample preparation: Following the preparation method in Example 1, 35mm samples were prepared respectively. 2 6mm 2 and 1.5mm 2 Three specifications of insulated wire core samples were tested after the insulation layer was made of XLPO flame-retardant polymer material and the length of the insulated wire core samples was not less than 10m. The samples were placed in an environment of (23±2)℃ and (50±5)% relative humidity for 24h. The results are recorded in Table 5.

[0084] Test methods and standards: The insulation thickness was measured in accordance with GB / T 2951.11-2008 using a projector. Six points were measured for each sample, and the average value was recorded. The average insulation thickness, the thinnest point thickness, and the outer diameter of the insulation were recorded.

[0085] Mechanical properties were tested in accordance with GB / T 2951.11-2008, with a tensile speed of 250 mm / min. Tensile strength and elongation at break were tested before aging and after aging in an air chamber at 158℃ for 168 h. The change rate before and after aging was calculated.

[0086] The thermal elongation test was conducted according to GB / T 2951.21-2008, with test conditions of 200℃ for 15 minutes. The elongation under load and the permanent deformation rate after cooling were recorded. The ozone resistance test was also conducted according to GB / T 2951.21-2008, with test conditions of 25℃ for 24 hours and an ozone concentration of 0.025-0.030%. The specimens were visually inspected for cracking.

[0087] The low-temperature tensile and winding tests were conducted according to GB / T 2951.14-2008, with a test temperature of -40℃ and a winding diameter as specified in the standard. The specimens were visually inspected for cracks. The heat shrinkage test was conducted according to GB / T 2951.13-2008, with test conditions of 130℃ and 1 hour. The shrinkage rate of the specimens was calculated.

[0088] The thermal shock test was conducted in accordance with GB / T 2951.31-2008, with test conditions of 150℃ for 6 hours. The specimens were then visually inspected for cracks.

[0089] The insulation resistance constant was tested according to GB / T 3048.5-2007, with insulation resistance tested at 90℃ and 20℃ respectively, and the insulation resistance constant calculated. The AC withstand voltage immersion test was conducted according to GB / T 3048.8-2007, with 2.5kV applied to the main conductor and 5kV applied to the ground conductor and signal conductor for 5 minutes, and the results observed for breakdown.

[0090] Hardness was tested in accordance with GB / T 2411-2008 and measured using a Shore A hardness tester.

[0091] Halogen content was tested in accordance with IEC 60754-1 and IEC 60754-2, and HCl content, pH value, conductivity and fluorine content were determined respectively.

[0092] In Table 5, "0.9 / 0.7 / 0.7" in the "Requirements" column correspond to the average insulation thickness requirements for the three cross-sectional specifications, respectively; "0.71 / 0.53 / 0.35" correspond to the minimum insulation thickness requirements for the three cross-sectional specifications, respectively.

[0093] Table 5 Performance Tests of Insulation Layers for Main Core and Ground Core

[0094] The test data in Table 5 show that the three specifications (35mm) 2 6mm 2 1.5mm 2 The insulation layer of the XLPO material significantly exceeded the standard requirements in all test items. In terms of structural dimensions, the thickness of the thinnest part of each specification was higher than the lower limit of the standard, indicating that the extrusion process was well controlled and the insulation layer was uniform. In the thermal elongation test, the elongation under load increased with the decrease of conductor cross-section, but all three were far below the upper limit of 100%, and the permanent deformation rate after cooling was 0%, indicating that the cross-linking degree of XLPO material was very sufficient and its deformation resistance at high temperature was excellent.

[0095] In terms of mechanical properties, the tensile strength before aging was higher than the standard lower limit of 8 MPa, with the 1.5 mm...2 The specification reaches 21MPa, significantly higher than 35mm. 2 16MPa and 6mm 2 After heat aging at 158℃ for 168 hours, the tensile strength change rate and elongation at break of the three specifications were all within the allowable range of ±30%. It is noteworthy that the elongation at break change rate showed a clear specification dependence; for the 35mm specification... 2 -6%, 6mm 2 -22%, 1.5mm 2 The value increased by 10%, and the smaller size changed from a negative value to a positive value. This may be related to the fact that the smaller size insulation layer underwent post-crosslinking or molecular chain rearrangement during the aging process, which led to an improvement in the material's flexibility.

[0096] In terms of electrical performance, the insulation resistance constant at 90℃ shows significant differences among the three specifications: 35mm² 2 112 MΩ·km, 6mm 2 It is 157 MΩ·km, while 1.5 mm 2 The resistance constant is only 22 MΩ·km, which is still far higher than the requirement of 3.67 MΩ·km, but the resistance constant of the small size is significantly lower.

[0097] In summary, the XLPO insulation layer meets the long-term use requirements of normal operating temperature of 125℃ in terms of thermal stability, electrical insulation and mechanical strength. The halogen test showed that the HCl content was less than 0.5%, the pH value was 5.2, the conductivity was 3μS / mm and the fluorine content was not detected, which meets the requirements of low smoke and halogen-free environmental protection.

[0098] 2. Signal Core Insulation Layer Performance Test Following the preparation method of Example 1, a signal core (0.5mm) was prepared. 2 Insulated wire core samples. The insulation layer is made of high yield strength elastomer material. The sample length is not less than 10m. After being placed in an environment of (23±2)℃ and (50±5)% relative humidity for 24h, the samples are tested and the results are recorded in Table 6.

[0099] Structural dimensions: The average insulation thickness, the thinnest insulation thickness, and the outer diameter of the insulation shall be measured in accordance with the provisions of GB / T 2951.11-2008.

[0100] Insulation thermal elongation: The test shall be conducted in accordance with the provisions of GB / T 2951.21-2008, with test conditions of 200℃ and 15min, and the elongation under load and the permanent deformation rate after cooling shall be tested respectively.

[0101] Mechanical properties of insulation before aging: Yield strength was tested according to GB / T 1040.2-2022, using dumbbell-shaped specimens, with a tensile speed of 50 mm / min, and stress-strain curves were obtained (e.g., Figure 5 The stress value corresponding to the yield point (as shown) is taken as the yield strength. Tensile strength and elongation at break are tested according to GB / T 1040.2-2022. The tensile speed is 250 mm / min. Ordinary insulating materials are subjected to tensile testing, and their stress-strain curves are shown below. Figure 6 As shown.

[0102] Mechanical properties of the air chamber after aging: The thermal aging test was carried out in accordance with GB / T 3512-2014, with aging conditions of 158℃ and 168h. After aging, the tensile strength and elongation at break were tested, and the rate of change was calculated.

[0103] Low-temperature tensile and winding tests: conducted in accordance with GB / T 2951.14-2008, with a test temperature of -40℃, and visual inspection of the specimens for cracking.

[0104] Thermal shock: Conducted in accordance with GB / T 2951.31-2008, with test conditions of 150℃ for 6 hours, and visual inspection of the specimens for cracking.

[0105] Heat shrinkage: The test shall be conducted in accordance with the provisions of GB / T 2951.13-2008, with test conditions of 130℃ and 1h, and the shrinkage rate shall be calculated.

[0106] Insulation resistance constant: The insulation resistance constant was tested according to GB / T 3048.5-2007 at 20℃ and 90℃ respectively.

[0107] Immersion AC withstand voltage test: Conducted in accordance with GB / T 3048.8-2007, with test conditions of 1.5kV / 5min, to check for breakdown.

[0108] Hardness: Tested in accordance with GB / T 2411-2008, using a Shore D hardness tester.

[0109] Ozone resistance: Conducted in accordance with GB / T 2951.21-2008, with test conditions of 25℃, 24h, ozone concentration of 0.025-0.030%, and visually inspect the sample for cracks.

[0110] Halogen content: Tested in accordance with IEC 60754-1 and IEC 60754-2, measuring HCl content, pH value, conductivity and fluorine content respectively.

[0111] Table 6 Performance Test of Signal Core Insulation Layer Average insulation thickness mm 0.5 0.5 Thickness at the thinnest point of insulation mm 0.35 0.42 Insulation outer diameter mm —— 2.0 Elongation under load % ≤100 10 Permanent deformation rate after cooling % ≤25 0 Yield strength MPa ≥20 23 Tensile strength MPa ≥15 30 Elongation at break % ≥300 600 Tensile strength change rate % Maximum ±30 7 Change rate of elongation at break % Maximum ±30 18 Low-temperature stretching and winding (-40℃) % No cracking pass Thermal shock (150℃, 6h) No cracking pass 130℃, 1 hour heat shrinkage % ≤4 0.5 Insulation resistance constant at 90℃ MΩ·km ≥3.67 657 Insulation resistance constant at 20℃ MΩ·km ≥3670 17381 Immersion AC withstand voltage test kV / min 1.5 / 5 Non-penetration qualified hardness D ≥60 65 Ozone resistance No cracking qualified HCL % ≤0.5 ＜0.5 pH value — ≥4.3 5.2 electrical conductivity μS / mm ≤10 3 Fluorine content % ≤0.1 Not detected The test results in Table 6 show that the material meets the requirements in all items and significantly exceeds the standard in most aspects. Combined with... Figure 5 and Figure 6 The comparison reveals a fundamental difference in the mechanical response behavior of the two materials. The stress-strain curve of ordinary insulating materials exhibits typical nonlinear characteristics. After yielding, the stress rapidly decreases and enters a large plastic deformation region. After unloading, significant permanent deformation and shrinkage occur. This indicates that ordinary materials are difficult to recover to their original dimensions when subjected to torsional deformation and will continue to exert compressive stress on the internal conductor. The stress-strain curve of the high-yield elastomer material used in this application shows a significant stress peak at the yield point, and the curve shows a steep upward trend near the yield point, indicating that the material can withstand high tensile stress without significant deformation before yielding. When the tensile stress exceeds the yield point, the curve does not drop sharply, but maintains a relatively stable downward trend, and ultimately maintains a high stress level before fracture, with a fracture elongation of up to 600%. Moreover, the material does not show significant shrinkage after being unloaded after being stretched to the yield point. After a certain deformation, the material can maintain the deformation state without returning to the original size. When the cable is subjected to tensile stress generated by torsion, the insulation layer can effectively resist deformation and maintain its original length, avoiding the signal core breakage or bulging problem caused by the insulation layer shrinking and squeezing the internal conductor.

[0112] After aging at 158℃ for 168 hours, the changes in tensile strength (+7%) and elongation at break (+18%) were both positive, indicating that further cross-linking or molecular chain ordering may have occurred within the material during aging, resulting in simultaneous enhancement of both strength and toughness. For the stress-strain curve, this implies that the yield peak and elongation at break may be higher after aging, validating the material's long-term thermal stability. Compared to the XLPO insulation layer in Table 5, the elongation at break of the high-yield elastomer is more than twice that of XLPO.

[0113] In terms of structural dimensions, the average insulation thickness is 0.5 mm, with a minimum thickness of 0.42 mm, exceeding the lower limit of 0.35 mm. During the thermal elongation test, the elongation under load was only 10%, and the permanent deformation rate after cooling was 0%, indicating sufficient cross-linking. Regarding electrical properties, the insulation resistance constant at 90℃ is 657 MΩ·km, and at 20℃ it is 17381 MΩ·km, both significantly better than the corresponding values ​​for XLPO in Table 5. This may be related to the higher volume resistivity of the high-yield elastomer material. The hardness is 65, and the ozone resistance and halogen content meet environmental protection requirements.

[0114] 3. Sheath performance test Sample preparation: Following the preparation method of Example 1, a sheath sample was prepared on the outermost layer of the finished cable. The sheath material was flame-retardant polyurethane. The sheath sample was cut from the finished cable, carefully peeled off, and then prepared into a test piece according to the corresponding standard requirements. After being placed in an environment of (23±2)℃ and (50±5)% relative humidity for 24 hours, the test was conducted, and the results were recorded in Table 7.

[0115] Test methods and standards: Mechanical properties of the sheath (before aging): Tensile strength and elongation at break were tested in accordance with GB / T 528-2009, with a tensile speed of 500 mm / min.

[0116] Mechanical properties after thermal aging: The thermal aging test was conducted in accordance with GB / T 3512-2014, with aging conditions of 110℃ and 168h. After aging, the tensile strength and elongation at break were tested, and the rate of change was calculated.

[0117] Mineral oil resistance test: The test shall be conducted in accordance with the provisions of GB / T 1690-2010. The test conditions are 100℃ and 168h. IRM 902 test oil shall be used. After immersion, the tensile strength and elongation at break shall be tested and the change rate shall be calculated.

[0118] High temperature pressure test: Conducted in accordance with GB / T 2951.31-2008, with test conditions of 100℃ and 4h, and calculate the percentage of indentation depth.

[0119] Thermal shock test: Conducted in accordance with GB / T 2951.31-2008, with test conditions of 150℃ and 1h. Visually inspect the specimen for cracks.

[0120] Low-temperature tensile test: The test shall be conducted in accordance with the provisions of GB / T 2951.14-2008, with a test temperature of -40℃, and the elongation after stretching shall be calculated.

[0121] Ozone resistance test: Conducted in accordance with GB / T 2951.21-2008, with test conditions of 25℃, 24h, ozone concentration of 0.025-0.030%, and visual inspection of the sample for cracking.

[0122] Water resistance test: The test shall be conducted in accordance with the provisions of GB / T 1690-2010. The test conditions are 80℃ and 168h. After immersion, the tensile strength and elongation at break shall be tested and the change rate shall be calculated.

[0123] Acid resistance test: The test shall be conducted in accordance with the provisions of GB / T 1690-2010. The test conditions are 23℃ and 168h. A 10% sulfuric acid solution shall be used. After immersion, the tensile strength and elongation at break shall be tested and the change rate shall be calculated.

[0124] Alkali resistance test: The test shall be conducted in accordance with the provisions of GB / T 1690-2010. The test conditions are 23℃ and 168h. A 10% sodium hydroxide solution shall be used. After immersion, the tensile strength and elongation at break shall be tested and the change rate shall be calculated.

[0125] Tear resistance test: The test shall be conducted in accordance with the provisions of GB / T 529-2008.

[0126] Saponification value test: The test shall be conducted in accordance with the provisions of GB / T 8021-2003, and the result shall be expressed as KOH.

[0127] Halogen content: Tested in accordance with IEC 60754-1 and IEC 60754-2, measuring HCl content, pH value, conductivity and fluorine content respectively.

[0128] Table 7 Sheath Performance Test Tensile strength before aging, minimum <![CDATA[N / mm 2 ]]> 20 28 Minimum elongation at break before aging % 300 510 The rate of change of tensile strength after aging, maximum % 30 +15 Minimum elongation at break after aging % 300 580 The rate of change in elongation at break after aging, with the maximum % 30 +10 The rate of change in tensile strength after exposure to mineral oil, maximum % 40 -28 Minimum elongation at break after mineral oil resistance % 300 560 The rate of change in elongation at break after resistance to mineral oil, maximum % 30 -6 Maximum indentation depth at 100℃ and 4 hours of high-temperature pressure. % 50 35 150℃, 1 hour thermal shock —— No cracking No cracking -40℃ low temperature tensile testing, minimum % 30 270 Ozone resistant at 25℃, 24h, and 0.025-0.030% concentration. —— No cracking No cracking The maximum rate of change in tensile strength after water resistance % 30 +6 Minimum elongation at break after water resistance % 100 580 The rate of change of tensile strength after acid resistance, maximum % 30 +5 Minimum elongation at break after acid resistance % 100 550 The rate of change of tensile strength after alkali resistance, maximum % 30 +8 Minimum elongation at break after alkali resistance % 100 570 Tear resistance N / mm 40 51 Saponification, maximum (based on KOH) mg / g 200 180 HCL % 0.5 Not detected pH value —— 4.3 4.7 electrical conductivity μS / mm 35 18 Fluorine content % 0.1 Not detected The test data in Table 7 show that the sheath material maintained excellent mechanical property stability under various working conditions, including before aging, after heat aging, and under resistance to oil, water, acid, and alkali. The tensile strength before aging was 28 N / mm². 2 The elongation at break was 510%. After heat aging at 110℃ for 168 hours, the change rate of tensile strength was +15% and the change rate of elongation at break was +10%, and the elongation at break after aging still reached 580%, indicating that the polyurethane material underwent a post-curing reaction during heat aging, and the degree of crosslinking was further improved, resulting in an increase in elongation. In the mineral oil resistance test, the change rate of tensile strength was -28% and the change rate of elongation at break was -6%, and the elongation at break still remained at 560%, indicating that the material has excellent resistance to mineral oil. Although the mechanical properties decreased slightly after oil immersion, they were still significantly higher than the lower limit of the standard.

[0129] The indentation depth in the high-temperature pressure test was 35%, indicating that the sheath has good resistance to deformation under high temperature and pressure. It did not crack under thermal shock, and the elongation at -40℃ reached 270%, maintaining excellent flexibility even in extremely cold conditions, ensuring the cable's crack resistance in low-temperature environments. After the water resistance test, the tensile strength change rate was +6%, and the elongation at break was still 580%. After the acid and alkali resistance tests, the tensile strength change rates were +5% and +8%, respectively, and the elongation at break were 550% and 570%, respectively, indicating that the sheath material has extremely strong chemical resistance to water, acids, and alkalis, with almost no performance degradation under hydrolytic and chemical corrosion environments. The tear strength was 51 N / mm, and the saponification value was 180 mg / g, indicating that the polyurethane has excellent resistance to hydrolysis and chemical corrosion.

[0130] Regarding halogens, HCl content was not detected, pH value was 4.7, conductivity was 18 μS / mm, and fluorine content was not detected, meeting the low-smoke halogen-free environmental protection standards. Overall, the flame-retardant polyurethane sheath exhibits excellent performance in multiple dimensions, including heat aging, oil resistance, water resistance, acid and alkali resistance, high and low temperature resistance, and tear resistance. In particular, the phenomenon that the elongation at break increased rather than decreased after heat aging and water immersion indicates that the sheath material can maintain or even improve its flexibility and crack resistance in harsh operating environments. This, combined with the design of fusion between the sheath and the aramid braided layer in this application, gives the cable excellent torsional resistance and long-term reliability.

[0131] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A torsion-resistant electric vehicle charging cable, characterized in that, include: The signal unit group (3) is made up of a ground wire core (31), a shielded signal core (32), an unshielded signal core group (33) and two auxiliary power lines (35). The signal unit group (3) is wrapped with an isolation strip (36) on the outside, and a nylon inner lining layer (37) is extruded on the outside of the isolation strip (36). The cable core body (4) is made of multiple main wire cores (2), signal unit group (3), center filler (9) and side filler (10) twisted together. The center filler (9) is located at the center of the cable core body (4), and the side filler (10) fills the gaps on the sides of the cable core body (4). Each main wire core (2), ground wire core (31), shielded signal core (32), unshielded signal core and auxiliary power line (35) has a center support structure (1) at the center of its conductor. The glue-cured filler (7) is used to fill all the gaps inside the cable core body (4); Reinforced nonwoven fabric (5) is wrapped around the outside of the cable core body (4); A fiber braided layer (6) is wrapped around the outside of the reinforced nonwoven fabric (5); The sheath (8) is extruded onto the outside of the fiber braided layer (6), and the material of the sheath (8) is embedded in the fiber gaps of the fiber braided layer (6), so that the sheath (8) and the fiber braided layer (6) are fused together.

2. The torsion-resistant electric vehicle charging cable according to claim 1, characterized in that, The central support structure (1) is made of multiple strands of aramid fibers (11) twisted together and coated with high-temperature resistant elastic adhesive. The central support structure (1) is made of a non-hygroscopic material. The conductors of the main core (2) and the ground core (31) are formed by twisting multiple strands of copper wire (12) with a diameter of 0.193±0.01mm around the central support structure (1). The conductors of the shielded signal core (32), the unshielded signal core, and the auxiliary power line (35) are formed by twisting multiple copper wires with a diameter of 0.15mm around the central support structure (1). The cross-section of a single signal core is 0.5mm. 2 The conductor tensile strength is ≥800N.

3. The torsion-resistant electric vehicle charging cable according to claim 1, characterized in that, The insulation layers of the main wire core (2), ground wire core (31) and auxiliary power line (35) are made of XLPO flame-retardant polymer material; the insulation layers of the shielded signal core (32) and the unshielded signal core are made of high yield strength elastomer material, with a yield strength ≥20MPa, tensile strength ≥25MPa, elongation at break ≥300%, and no shrinkage after stretching.

4. The torsion-resistant electric vehicle charging cable according to claim 1, characterized in that, The unshielded signal core group (33) is composed of 8 unshielded signal cores twisted together with a twisting pitch ratio of 9, and is wrapped with an isolation strip (36) on the outside; the shielded signal core (32) is composed of two signal cores and a composite shielding layer that covers the outside of the two signal cores. The composite shielding layer includes an aluminum foil layer wrapped around the outside of the two signal cores and a tinned copper wire braided layer woven around the outside of the aluminum foil layer, with a braiding density ≥80%; the ground core (31), the shielded signal core (32), the unshielded signal core group (33) and the two auxiliary power lines (35) are twisted together to form a signal unit group (3) with a twisting pitch ratio of 10.

5. A torsion-resistant electric vehicle charging cable according to claim 1, characterized in that, The central filler (9) is a circular high-hardness elastomer, and the side filler (10) is a vulcanized rubber strip; the glue-cured filler (7) is a quick-drying glue that is elastic after curing.

6. A torsion-resistant electric vehicle charging cable according to claim 1, characterized in that, The fiber braided layer (6) is an aramid fiber braided layer with a braiding density of 25-35%; the sheath (8) is made of flame-retardant polyurethane material; the surface of the sheath (8) is provided with several uniform arc-shaped protrusions.

7. A method for preparing a torsion-resistant electric vehicle charging cable as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Conductor preparation: A central support structure (1) is set at the center of the conductors of the main conductor (2) and the ground conductor (31). Multiple copper wires are twisted into copper wire strands (12). The multiple copper wire strands (12) are then twisted around the central support structure (1). The direction of the copper wire strands (12) is consistent with the direction of the twisting of the copper wire strands (12). The conductors are compacted using a nano-coating mold to form the conductive parts of each conductor. A central support structure (1) is set at the center of the conductors of the shielded signal core (32), the unshielded signal core and the auxiliary power line (35). Multiple copper wires are twisted around the central support structure (1). The conductors are compacted using a nano-coating mold to form the conductive parts of each conductor. S2, insulation extrusion: XLPO flame-retardant polymer material is extruded over the conductors of the main conductor (2), ground conductor (31) and auxiliary power line (35) to form an insulation layer, and high yield strength elastomer material is extruded over the conductors of the shielded signal core (32) and unshielded signal core to form an insulation layer; S3, Signal unit group (3) cabling: multiple unshielded signal cores are twisted together to form an unshielded signal core group (33); aluminum foil and braided tinned copper wire are wrapped around the outside of two signal cores to form a shielded signal core (32); the ground core (31), shielded signal core (32), unshielded signal core group (33) and two auxiliary power lines (35) are twisted together, wrapped with isolation tape (36) and then extruded with nylon inner lining layer (37) to form signal unit group (3); S4, Cable core body (4): Multiple main wire cores (2), signal unit group (3), center filler (9) and side filler (10) are twisted together to form cable core body (4), and the twisted cable core body (4) is shaped. S5. Filling gaps: Impregnate the stranded cable core body (4) with paste-like quick-drying elastic glue so that the glue fills all the gaps inside the cable core body (4). After scraping off the excess glue, wrap a reinforcing non-woven fabric (5) around the outside of the cable core body (4) with the polyester side of the non-woven fabric facing inward. S6, Fiber weaving: A fiber weaving layer (6) is woven on the outside of the reinforced nonwoven fabric (5), with a weaving density of 25-35%; S7, Sheath (8) extrusion: Sheath (8) is extruded on the outside of fiber braided layer (6), so that the molten sheath (8) material is embedded in the fiber gaps of fiber braided layer (6) and fused together with fiber braided layer (6).

8. The method for preparing a torsion-resistant electric vehicle charging cable according to claim 7, characterized in that, In step S4, the twisted pitch ratio is ≤16 times, and two pressing dies are used for shaping.

9. A method for preparing a torsion-resistant electric vehicle charging cable according to claim 7, characterized in that, In step S7, the raw material of the sheath (8) is dried to a moisture content of ≤200PPM before extrusion, and the extrusion is carried out using a special mold with an arc-shaped groove at the die sleeve outlet.

Images