Cable for ultra-flexible high-voltage charging pile and preparation method thereof

Abstract

The invention discloses an ultra-flexible cable for a high-voltage charging pile and a preparation method of the ultra-flexible cable, and aims to solve the problems that an existing cable for the high-voltage charging pile is insufficient in flexibility, short in bending-resistant service life and poor in signal stability under high voltage. The cable comprises a conductor, an insulating layer, a shielding layer, a signal line group and a sheath layer, the conductor is made of superfine oxygen-free copper wires through layered different-direction back-twist bunch stranding and compound stranding, and a flexible aramid fiber core is arranged in the center of the conductor. The insulating layer is of a TPU / TPE double-layer co-extrusion structure; the shielding layer adopts a composite structure of a semi-conductive elastomer extruded layer and a superfine silver-plated copper wire braid layer; the signal line groups are symmetrically arranged in a star shape; and the sheath layer is made of a nano modified TPEE material. The preparation method focuses on optimization of conductor stranding, double-layer co-extrusion, annealing treatment and tension control processes; the bending radius of the cable is less than or equal to 3D, the bending service life is long, the cable can bear 1000VDC high voltage and large current transmission, and the cable has excellent shielding effectiveness, wear resistance and weather resistance, and is suitable for high-frequency mobile scenes such as electric vehicle alternating current and direct current charging guns.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of charging pile cables, and particularly relates to an ultra-flexible high-voltage charging pile cable and a preparation method thereof. BACKGROUND

[0002] With the rapid development of the electric vehicle industry, high-voltage fast charging technology has become the mainstream trend in the industry, and higher requirements are put forward for the performance of charging pile cables. On the one hand, the charging gun needs to be frequently plugged and bent, and the cable needs to have extremely high flexibility and bending life; on the other hand, under the 1000VDC high-voltage and large-current transmission scenario, the cable needs to meet the requirements of insulation reliability, electromagnetic shielding effectiveness and mechanical protection performance at the same time.

[0003] In the prior art, such as the high-flexibility wear-resistant and corrosion-resistant DC power transmission charging pile cable disclosed in CN217506917U, a sixth type of ultra-soft tinned copper wire is used as the conductor, and a polyurethane elastomer is used as the sheath. Although the flexibility is improved to some extent, there are the following deficiencies: first, the conductor adopts a conventional bundle twisting process, and the bending radius is usually only 5D or more. After long-term bending, the copper wire is prone to loosen, affecting the stability of the conductor; second, the insulation layer is a single-layer structure, and it is difficult to balance the insulation durability and anti-friction performance under high voltage; third, the shielding layer is woven with single tinned copper wire, and the weaving density is only about 90%, which is insufficient in electromagnetic shielding effectiveness, and the weaving layer is prone to breakage due to bending during long-term use; fourth, the signal line and the power line core are arranged mixedly, which is prone to signal interference, affecting the charging control accuracy; and fifth, the sheath material is not modified, and the wear resistance and oil stain resistance are limited, which is difficult to adapt to the complex use environment of the charging pile.

[0004] In addition, in the existing preparation process, the tension control precision of the conductor twisting is insufficient, and stress concentration is prone to occur during double-layer co-extrusion, resulting in a decrease in the flexibility of the cable and a shortening of the service life. SUMMARY

[0005] In view of the above problems, the purpose of the present application is to provide an ultra-flexible high-voltage charging pile cable and a preparation method thereof, which can realize stable transmission of the cable under high voltage and large current, reduce the bending radius to within 3D, have high bending life, and balance the electromagnetic shielding effectiveness and mechanical protection performance.

[0006] The purpose of the present application is achieved by the following technical solutions: An ultra-flexible high-voltage charging pile cable comprises, from inside to outside, a conductor, an insulation layer, a shielding layer, a signal line group, a sheath layer and a filler; the conductor and the insulation layer form a power line core; the power line core and the signal line group are twisted together, and the twisted gap is filled with the filler; the power line core and the signal line group are covered with the shielding layer and the sheath layer after being twisted; the conductor is made of oxygen-free copper wire which is twisted after being pretreated by acid washing and drying, and then is re-twisted; a flexible aramid core is arranged at the center of the conductor; the insulation layer is a double-layer co-extrusion structure composed of an inner insulation layer and an outer insulation layer; the shielding layer is a composite structure composed of an inner shielding layer and an outer shielding layer. The diameter of the oxygen-free copper wire is 0.08-0.1 mm, the bundle-twisted pitch is 8-10 times the bundle diameter, the re-twisted pitch is 12-15 times the re-twisted outer diameter, and the directions of the bundle-twisted and the re-twisted are opposite.

[0007] The inner insulation layer is made of high dielectric strength TPU material, and the outer insulation layer is made of low friction coefficient TPE material, and the total thickness is 0.9-1.4 mm; the dielectric strength of the TPU material of the inner insulation layer is ≥25 kV / mm, the volume resistivity is >10 14 Ω·cm; the friction coefficient of the TPE material of the outer insulation layer is ≤0.3, and the elongation at break is >500%.

[0008] The inner shielding layer is a semi-conductive elastomer extrusion layer, and the outer shielding layer is a woven layer of superfine silver-plated copper wire, the weaving density is ≥95%, and the weaving angle is 30-45°.

[0009] The signal line group comprises two pairs of CAN buses and two charging confirmation lines, and is symmetrically distributed in the gap between the power line cores in a star shape and is wrapped into a bundle by a flexible polyester tape.

[0010] The filler is a high-flame-retardant polypropylene rope, the diameter of a single rope is 0.5-1.0 mm, and the filling density ensures that the cable structure is round and has no obvious gap.

[0011] The number of the power line cores is three, which are two main power line cores and one ground line core, the cross-sectional area of a single conductor is 16-50 mm², and the DC resistance of the conductor is ≤0.012 Ω / m.

[0012] A preparation method of an ultra-flexible high-voltage charging pile cable comprises the following steps: S1: Conductor preparation: after being pretreated by acid washing and drying, the oxygen-free copper wire is twisted in a layered and opposite direction around the flexible aramid core, and then is re-twisted to form the conductor after being annealed at 200-250°C under nitrogen protection; S2: Insulation layer and shielding layer forming: TPU material and TPE material are simultaneously extruded on the conductor to form the insulation layer, and a semi-conductive elastomer material is extruded on the insulation layer to form the inner shielding layer, and then the outer shielding layer is formed by weaving superfine silver-plated copper wire; S3: Signal line group preparation: twist the CAN bus conductor with the insulating layer to form a wire pair, arrange the charging confirmation line in a star type symmetry, and then wrap the wire pair into a bundle with a flexible polyester tape; S4: Cabling and sheath layer forming: put the three power line cores, signal line groups and high-flame-retardant polypropylene rope filler into a cabling machine together for twisting, and the twisting pitch is 12-16 times the outer diameter of the cable; after twisting, the nanometer modified TPEE sheath layer is extruded and coated, and the finished product cable is obtained after cooling, traction and take-up; wherein the take-up and pay-off process of steps S1 and S4 adopts a constant tension control system, and the tension error is ≤±0.5N.

[0013] In step S1, a double-station asynchronous untwisting bundle twisting machine is used, the bundle twisting speed is 800-1200r / min, the re-twisting speed is 300-500r / min, the directions of the bundle twisting and the re-twisting are opposite, and the tension is controlled by a servo motor in a closed loop.

[0014] In step S2, the double-layer co-extrusion die adopts a gradually changing flow channel structure, the flow channel taper angle is 15-20°, the extrusion temperature is 160-190℃, the traction speed is 10-15m / min, and the eccentricity of the insulating layer is ≤5%; in step S4, the sheath layer extrusion adopts a single screw extruder, the screw length-diameter ratio is 25:1, the extrusion temperature is 170-200℃, the take-up speed is adjusted in real time by an infrared temperature detector, and the surface temperature of the sheath layer is ≤60℃.

[0015] The beneficial effects of the present application are as follows: Through the combination design of the layered anisotropic untwisting bundle twisting + re-twisting structure of the conductor, the center aramid core support, the optimization of the shielding layer braid angle and the low hardness sheath material, the bending radius of the cable is ≤3D, and the bending life is high.

[0016] The insulating layer adopts a TPU / TPE double-layer co-extrusion structure, the dielectric strength of the TPU material of the insulating inner layer is ≥25kV / mm, can stably withstand 1000VDC high voltage, and has no breakdown phenomenon; the design of the semi-conductive elastomer extrusion coating eliminates the gap between the insulation and the shielding layer, avoids local electric field concentration, and improves the use safety under high voltage.

[0017] The electromagnetic shielding effect is outstanding: the semi-conductive extrusion coating of the composite shielding structure can suppress the corona discharge on the insulating surface, the braid density of the outer silver-plated copper wire braid layer is ≥95%, the shielding attenuation is ≥80dB, the external electromagnetic interference and internal electric field radiation are effectively blocked, the stability of the CAN bus signal transmission is ensured, and the charging control precision is improved by 15-20%.

[0018] The preparation process is stable and controllable: a double-station asynchronous untwisting bundle twisting machine, a gradually changing flow channel double-layer co-extrusion die and a constant tension control system are used to realize precise control of conductor twisting, insulation and shielding forming and sheath extrusion, ensure product consistency, high finished product qualification rate and high production efficiency compared with traditional process. BRIEF DESCRIPTION OF DRAWINGS

[0019] The application will be described in further detail below with reference to the drawings.

[0020] Figure 1 is a schematic diagram of the cross-sectional structure of the application.

[0021] Shown in the figure: 1 - conductor; 11 - oxygen-free copper wire; 12 - flexible aramid core; 2 - insulation layer; 21 - inner insulation layer; 22 - outer insulation layer; 3 - shielding layer; 31 - inner shielding layer; 32 - outer shielding layer; 4 - signal line group; 5 - sheath layer; 6 - filler. DETAILED DESCRIPTION

[0022] The embodiments of the present application will be described in detail below with reference to specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in the specification.

[0023] It should be understood that the structures, proportions, sizes, etc. shown in the drawings of the specification are only used to understand and read the content disclosed in the specification by those skilled in the art, and are not used to limit the conditions that the present application can be implemented, and therefore do not have technical significance. Any modification of the structure, change of the proportional relationship, or adjustment of the size, without affecting the effects that the present application can produce and the purposes that the present application can achieve, should still fall within the scope of the technical content disclosed by the present application. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and the like used in the specification are only for the convenience of clear description, and are not used to limit the scope of the present application that can be implemented, and the change or adjustment of the relative relationship, without substantially changing the technical content, is also considered as the scope of the present application that can be implemented.

[0024] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances. It should be noted that the terms "include", "contain" or any other variant are intended to cover non-exclusive inclusion, so that the process, method, article or equipment containing a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or equipment. Example 1

[0025] An ultra-flexible high-voltage charging pile cable, the conductor 1 uses a diameter of 0.08mm oxygen-free copper wire 11, a diameter of 1.0mm flexible aramid core 12 is arranged in the center, the bundle twisting pitch is 8 times of the bundle diameter, the complex twisting pitch is 12 times of the complex twisting outer diameter, the bundle twisting and the complex twisting directions are opposite, the conductor 1 cross-sectional area is 16mm², and the direct current resistance is 0.011Ω / m (20℃).

[0026] The insulating inner layer 21 is made of TPU material with a thickness of 0.6mm, a dielectric strength of 26kV / mm, the insulating outer layer 22 is made of TPE material with a thickness of 0.3mm and a friction coefficient of 0.28; the shielding inner layer 31 is made of a semi-conductive elastomer extrusion layer with a thickness of 0.2mm, a volume resistivity of 10 4 Ω·cm, the shielding outer layer 32 is a super-fine silver-plated copper wire braid layer with a braid density of 95% and a braid angle of 30°; the signal line group 4 includes 2 pairs of CAN buses and 2 charging confirmation lines, and is arranged in a star type symmetry; the CAN bus twisting pitch is 8mm, and the line pair insulation layer dielectric constant is 2.2; the sheath layer 5 is a modified TPEE material added with 5wt% nano-SiO2 and 3wt% fluororubber particles, and has a Shore A hardness of 82 and a 100,000 times friction thickness loss of 7.5%.

[0027] A preparation method of an ultra-flexible high-voltage charging pile cable is as follows: S1: Conductor 1 preparation: the oxygen-free copper wire 11 is pickled by 5% dilute sulfuric acid, dried at 120℃ for 3 hours, layered and twisted in different directions by using a double-station asynchronous twist bundle twisting machine, the bundle twisting speed is 800r / min, the tension is 0.3N, the bundle is annealed at 200℃ under nitrogen protection for 3 seconds after bundle twisting, and the complex twisting speed is 300r / min, thereby the conductor 1 is prepared; S2: Insulation layer and shielding layer forming: the extrusion temperature of the double-layer co-extrusion equipment is 160℃, the traction speed is 10m / min, the taper angle of the gradual change flow channel die is 15°, the TPU / TPE insulation layer and the semi-conductive shielding inner layer 31 are synchronously extruded, and then the silver-plated copper wire is braided to form the shielding outer layer 32; S3: Signal line group 4 preparation: the CAN bus insulation layer extrusion temperature is 150℃, the line pair twisting pitch is 8mm, and the charging confirmation line is wrapped after being arranged in a star type by using a polyester tape with a pitch of 20mm; S4: Cabling and sheath forming: the cabling twisting pitch is 12 times of the cabling outer diameter, the sheath extrusion temperature is 170℃, the take-up speed is adjusted by feedback adjustment of infrared temperature measurement, and the sheath surface temperature is controlled at about 55℃.

[0028] The cable prepared in the embodiment has a bending radius of 2.8D, the conductor 1 resistance change rate is less than or equal to 1% after 500,000 times of bending, there is no breakdown in the 1000VDC high-voltage pressure test, the shielding attenuation is 82dB, and the use requirements of the 1000VDC grade charging pile are met. Example 2

[0029] An ultra-flexible high-voltage charging pile cable, the conductor 1 adopts a diameter of 0.1mm of oxygen-free copper wire 11, a diameter of 1.2mm of flexible aramid core 12 is arranged in the center, the bunching pitch is 10 times of the bundle diameter, the re-twisting pitch is 15 times of the re-twisting outer diameter, the directions of the bunching and the re-twisting are opposite, the cross-sectional area of the conductor 1 is 50mm2, and the direct current resistance is 0.004Ω / m (20℃).

[0030] The thickness of the insulating inner layer 21 is 0.9mm, the dielectric strength is 28kV / mm, the thickness of the insulating outer layer 22 is 0.5mm, and the friction coefficient is 0.25; the thickness of the shielding inner layer 31 is 0.3mm, the volume resistivity is 5*10³Ω*cm, the shielding outer layer 32 is a super-fine silver-plated copper wire braiding layer with a braiding density of 98% and a braiding angle of 45°; the signal line group 4 includes two pairs of CAN buses and two charging confirmation lines, which are arranged in a star-shaped symmetry, the CAN bus twisting pitch is 12mm, and the dielectric constant of the wire pair insulation layer is 2.1; the sheath layer 5 is a modified TPEE material added with 8wt% of nano-SiO2 and 5wt% of fluororubber particles, the Shore hardness A is 85, and the friction thickness loss is 6.8% after 100,000 times of friction.

[0031] The preparation method of the embodiment is different from that of the embodiment 1 in that the bunching rotation speed is adjusted to 1200r / min, the re-twisting rotation speed is 500r / min, the annealing temperature is 250℃, the double-layer co-extrusion temperature is 190℃, the traction speed is 15m / min, and the sheath extrusion temperature is 200℃.

[0032] The cable prepared in the embodiment has a bending radius of 3.0D, the resistance change rate of the conductor 1 is less than or equal to 0.8% after 500,000 times of bending, there is no breakdown in the high-voltage resistance test under 1000VDC, the shielding attenuation is 85dB, and the cable is suitable for a large-current fast-charging scene.

[0033] The protection scope of the present application is not limited to the technical solutions disclosed in the specific embodiments, and any modification, equivalent replacement, improvement, etc. made according to the technical essence of the present application to the above embodiments all fall within the protection scope of the present application.

Claims

1. A cable for an ultra-flexible high-voltage charging pile, characterized in that: From the inside out, it includes a conductor (1), an insulation layer (2), a shielding layer (3), a signal wire group (4), a sheath layer (5), and a filler (6); the conductor (1) and the insulation layer (2) constitute a power core; the power core and the signal wire group (4) are twisted together, and the twisting gap is filled with filler (6); the power core and the signal wire group (4) are covered with a shielding layer (3) and a sheath layer (5) after being twisted together; the conductor (1) is made of oxygen-free copper wire (11) after being layered and twisted in opposite directions and then re-stretched; a flexible aramid core (12) is provided in the center of the conductor (1); the insulation layer (2) is a double-layer co-extruded structure composed of an inner insulation layer (21) and an outer insulation layer (22); the shielding layer (3) is a composite structure composed of an inner shielding layer (31) and an outer shielding layer (32).

2. The cable for an ultra-flexible high-voltage charging pile according to claim 1, characterized in that: The oxygen-free copper wire (11) has a diameter of 0.08-0.1 mm, a stranding pitch of 8-10 times the strand diameter, a double stranding pitch of 12-15 times the double strand outer diameter, and the stranding and double stranding directions are opposite.

3. The cable for an ultra-flexible high-voltage charging pile according to claim 1, characterized in that: The inner insulating layer (21) is made of high dielectric strength TPU material, and the outer insulating layer (22) is made of low friction coefficient TPE material, with a total thickness of 0.9-1.4 mm; the dielectric strength of the TPU material in the inner insulating layer (21) is ≥25 kV / mm, and the volume resistivity is >10. 14 Ω・cm; the coefficient of friction of the insulating outer layer (22) TPE material is ≤0.3 and the elongation at break is >500%.

4. The cable for an ultra-flexible high-voltage charging pile according to claim 1, characterized in that: The inner shielding layer (31) is a semi-conductive elastomer extrusion layer, and the outer shielding layer (32) is an ultra-fine silver-plated copper wire braided layer with a braiding density ≥95% and a braiding angle of 30-45°.

5. The cable for an ultra-flexible high-voltage charging pile according to claim 1, characterized in that: The signal line group (4) includes two pairs of CAN buses and two charging confirmation lines, which are symmetrically distributed in a star shape in the gap between the power line cores and are bundled together by flexible polyester tape.

6. The cable for an ultra-flexible high-voltage charging pile according to claim 1, characterized in that: The filler (6) is a high flame-retardant polypropylene rope with a single diameter of 0.5-1.0 mm. The filling density ensures that the cable structure is round and without obvious gaps.

7. The cable for an ultra-flexible high-voltage charging pile according to claim 1, characterized in that: The number of power conductors is 3, namely 2 main power conductors and 1 grounding conductor. The cross-sectional area of ​​a single conductor (1) is 16-50mm², and the DC resistance of conductor (1) is ≤0.012Ω / m (20℃).

8. A method for preparing an ultra-flexible high-voltage charging pile cable according to any one of claims 1-8, characterized in that: Includes the following steps: S1: Conductor (1) preparation: After acid washing and drying pretreatment, oxygen-free copper wire (11) is layered and twisted in opposite directions with flexible aramid core (12) as the center. After twisting, it is subjected to nitrogen protection annealing at 200-250℃ and then re-stretched to form conductor (1). S2: Insulation layer (2) and shielding layer (3) forming: Using a double-layer co-extrusion equipment, TPU material and TPE material are simultaneously extruded onto the conductor (1) to form insulation layer (2), and semi-conductive elastomer material is extruded onto the insulation layer (2) to form shielding inner layer. Then, ultra-fine silver-plated copper wire is woven to form shielding outer layer. S3: Signal line group (4) preparation: Twist the CAN bus conductor and the insulating layer (2) to form a wire pair, arrange them symmetrically with the charging confirmation line in a star shape, and then wrap them into a bundle with flexible polyester tape; S4: Cable forming and sheath layer (5) forming: Three power cores, signal wire group (4) and high flame retardant polypropylene rope filler (6) are put into the cable forming machine for stranding. The stranding pitch is 12-16 times the outer diameter of the cable. After stranding, a nano-modified TPEE sheath layer (5) is extruded. After cooling, pulling and winding, the finished cable is obtained. Among them, the winding and unwinding process of steps S1 and S4 adopts a constant tension control system with a tension error ≤ ±0.5N.

9. The preparation method according to claim 8, characterized in that: In step S1, a dual-station asynchronous untwisting twisting machine is used. The twisting speed is 800-1200 r / min, and the re-twisting speed is 300-500 r / min. The twisting and re-twisting are in opposite directions, and the tension is controlled by a closed loop servo motor.

10. The preparation method according to claim 8, characterized in that: In step S2, the double-layer co-extrusion die adopts a gradient flow channel structure with a flow channel cone angle of 15-20°, an extrusion temperature of 160-190℃, a traction speed of 10-15m / min, and an eccentricity of the insulation layer (2) of ≤5%. In step S4, the sheath layer (5) is extruded using a single screw extruder with a screw length-to-diameter ratio of 25:1 and an extrusion temperature of 170-200℃. The take-up speed is adjusted in real time by feedback from an infrared thermometer to ensure that the surface temperature of the sheath layer (5) is ≤60℃.

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