Anti-siphon XL-PVDF insulated wire for automobile gearbox and preparation method of anti-siphon XL-PVDF insulated wire

Abstract

The invention provides an anti-siphon XL-PVDF insulated wire for an automobile gearbox and a preparation method of the anti-siphon XL-PVDF insulated wire, and belongs to the technical field of special wires and cables. The anti-siphon XL-PVDF insulated wire for the automobile gearbox comprises a sealing compound conductor and an insulating layer, and the insulating layer wraps the sealing compound conductor. The sealing compound conductor is formed by twisting a plurality of copper wires, waterproof glue is filled in twisting gaps, and micro gaps among all the copper wires are completely filled with the waterproof glue to form a first anti-siphon barrier; the insulating layer is tightly coated outside the sealing compound conductor, and waterproof silica gel is filled between the inner wall of the insulating layer and the sealing compound conductor. On the premise of not depending on traditional ointment filling or water-blocking tape wrapping, the cable is compact in structure, resistant to high temperature and oil, high in long-term reliability and capable of completely meeting harsh anti-siphon requirements, extra structures such as a wrapping layer are omitted, and the cable is simpler and more compact in structure.

Description

Technical Field

[0001] This invention relates to the field of special wire and cable technology, and more specifically, to an anti-siphon XL-PVDF insulated wire for automotive gearboxes and its preparation method. Background Technology

[0002] Currently, with the development of the automotive industry, transmissions are becoming increasingly intelligent and electronically controlled, placing increasingly stringent requirements on the reliability of their internal wiring. Cables need to operate stably for extended periods in extreme environments such as high temperatures, oil contamination, vibration, and condensation. Among these requirements, the "anti-siphon" performance (preventing liquid from backflowing along conductor gaps) is crucial for ensuring the safety of the transmission's electronic control system.

[0003] In existing technologies, there are two main technical solutions commonly used in the industry to achieve the anti-siphon function of cables: The first method is the "conductor filling scheme": waterproof grease is filled into the gaps between the strands of the stranded conductor to block the channels for liquid penetration. This technique is commonly used in many communication cables and some special cables.

[0004] The second method is the "water-blocking tape wrapping scheme": a layer of water-swellable powder or tape is wrapped around the conductor. When the liquid comes into contact with it, the material expands, thereby preventing the liquid from penetrating further.

[0005] The existing technical solutions have the following drawbacks: 1. Insufficient high temperature resistance: Traditional waterproof grease is prone to evaporation, drying or dripping in the long-term high temperature environment of the transmission (150°C), which can cause the anti-siphon function to fail and may contaminate the transmission fluid, affecting the normal operation of the transmission.

[0006] 2. Complex structure and poor reliability: The water-blocking tape solution increases the structural size and process complexity of the cable. In addition, the water-blocking tape may loosen under the strong vibration environment of the gearbox, raising questions about its long-term reliability.

[0007] 3. Incompatible with the trend of miniaturization: Automotive parts are increasingly pursuing miniaturization and lightweighting, and additional water-blocking layers are not conducive to the miniaturization design of cables. Summary of the Invention

[0008] To overcome the above deficiencies, this invention provides an anti-siphon XL-PVDF insulated wire for automotive transmissions and its preparation method, aiming to improve the aforementioned problems.

[0009] This invention is implemented as follows: In a first aspect, an embodiment of the present invention provides an anti-siphon XL-PVDF insulated wire for automotive transmissions, comprising a sealing conductor and an insulating layer, wherein the insulating layer encapsulates the sealing conductor.

[0010] The sealing conductor is made of multiple copper wires twisted together, and the gaps between the twists are filled with waterproof adhesive. The waterproof adhesive completely fills the microscopic gaps between all the copper wires, forming the first anti-siphon barrier. The insulating layer tightly covers the sealing conductor, and the space between the inner wall of the insulating layer and the sealing conductor is filled with waterproof silicone.

[0011] In one embodiment of the present invention, the sealing conductor is made of 19 strands of soft copper wire, and the waterproof adhesive is a silicone-based waterproof adhesive.

[0012] In one embodiment of the present invention, each of the soft copper wires has a diameter of 0.19 mm and a nominal cross-sectional area of ​​0.5 mm². 2 .

[0013] In one embodiment of the present invention, the insulating layer is an irradiated cross-linked polyvinylidene fluoride layer; the insulating layer is subjected to electron beam irradiation cross-linking treatment to achieve a rated temperature of 150°C.

[0014] In one embodiment of the present invention, the nominal outer diameter of the insulating layer is 1.72 mm and the thickness is 0.19 mm.

[0015] Secondly, embodiments of the present invention further provide a method for preparing an anti-siphon XL-PVDF insulated wire for automotive transmissions, comprising the anti-siphon XL-PVDF insulated wire for automotive transmissions as described in any one of the above-mentioned embodiments; and the following steps: S1. Conductor sealing: 19 copper wires of 0.19mm are twisted together using a stranding device, and liquid waterproof adhesive is injected at the twisting point to allow the adhesive to fully penetrate and cure, forming a dense sealed conductor. S2. Insulation extrusion: PVDF insulation material is fed into an extruder, heated and melted, and then extruded onto the sealant conductor obtained in step S1. S3. Air cooling: The extruded wire core is passed through a cooling tank and naturally cooled and shaped by air to ensure that the stress of the insulation layer is fully released, and then it is wound into a coil. S4. Irradiation crosslinking: The cooled cable is irradiated through an electron accelerator to crosslink the PVDF molecular chains and obtain the final XL-PVDF insulation layer.

[0016] In one embodiment of the present invention, in S1, 19 tin-plated copper wires with a diameter of 0.19 mm are used, with a stranding pitch of 15 times the diameter, and high-temperature resistant silicone-based waterproof adhesive is injected simultaneously during stranding.

[0017] In one embodiment of the present invention, in S2, a vacuum of -0.06 MPa to -0.08 MPa is applied to the die head area during extrusion to remove air gaps and moisture present at the interface between the insulation layer and the conductor.

[0018] In one embodiment of the present invention, in S2, a 40-type single-screw extruder is used; the temperature zones are set as follows: zone 1 220°C, zone 2 240°C, zone 3 250°C, die head 260°C, and die opening 270°C; the die head is equipped with a honeycomb plate and no filter screen is added.

[0019] In one embodiment of the invention, in S4, the cooled cable is irradiated at a dose of 8-12 Mrad.

[0020] The beneficial effects of this invention are: 1. By combining "internal sealing and blocking" and "vacuum extrusion densification", the siphon channel is fundamentally eliminated, achieving a penetration of <5mm without the need for traditional water-blocking structures, thus solving the problem of grease failure at high temperatures.

[0021] 2. Using XL-PVDF as the insulation material and optimized irradiation, the product simultaneously meets the requirements of long-term heat resistance at 150℃, resistance to various chemical media, high mechanical strength, and anti-siphon performance, making it fully adaptable to the extreme environment of gearboxes.

[0022] 3. Without relying on traditional grease filling or water-blocking tape wrapping, it meets the requirements of compact structure, high temperature resistance, oil resistance, high long-term reliability, and can fully meet the stringent anti-siphon requirements. It eliminates the need for additional structures such as wrapping layers, making the cable structure simpler and more compact, which is conducive to the miniaturization design of automotive parts.

[0023] 4. A vacuum-cooled extrusion process was designed specifically for the characteristics of PVDF materials. During insulation extrusion, a "meshless filtration + vacuum" method was employed, effectively ensuring consistent product quality and performance. The production process is more environmentally friendly and efficient. The product can simultaneously meet the aforementioned long-term aging, liquid compatibility, and anti-siphon (<5mm) test requirements. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that similar labels and letters in the following embodiments represent similar items. Therefore, once an item is defined in one embodiment, it does not need to be further defined and explained in subsequent embodiments.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] Example The present invention provides an anti-siphon XL-PVDF insulated wire for automotive transmissions, comprising a sealing conductor and an insulation layer, wherein the insulation layer wraps the sealing conductor.

[0029] The sealing conductor is made of multiple copper wires twisted together, and the gaps between the twists are filled with waterproof adhesive. The waterproof adhesive completely fills the microscopic gaps between all the copper wires, forming the first anti-siphon barrier. The insulating layer tightly covers the sealing conductor, and the space between the inner wall of the insulating layer and the sealing conductor is filled with waterproof silicone.

[0030] In one embodiment of the present invention, the sealing conductor is made of 19 strands of soft copper wire, and the waterproof adhesive is a silicone-based waterproof adhesive.

[0031] In one embodiment of the present invention, each of the soft copper wires has a diameter of 0.19 mm and a nominal cross-sectional area of ​​0.5 mm². 2 .

[0032] In one embodiment of the present invention, the insulating layer is an irradiated cross-linked polyvinylidene fluoride layer; the insulating layer is subjected to electron beam irradiation cross-linking treatment to achieve a rated temperature of 150°C.

[0033] In one embodiment of the present invention, the nominal outer diameter of the insulating layer is 1.72 mm and the thickness is 0.19 mm.

[0034] Through the dual barrier of "conductor sealing + vacuum insulation extrusion", the average penetration distance in the anti-siphon test (175℃×48h) is 2.5mm, which is far lower than the traditional grease solution (penetration ≥20mm at 150℃×48h) and the water-blocking tape solution (penetration ≥15mm after vibration), fully meeting the stringent requirement of "penetration <5mm" for gearboxes; and after 150℃×3000h heat aging, the anti-siphon performance has not degraded (penetration distance is still ≤3mm), breaking through the bottleneck of traditional anti-siphon technology and solving the problem of high-temperature failure of traditional solutions.

[0035] It can withstand long-term heat of 150℃ (traditional PVDF cables can only withstand 120℃), and can be immersed in 150℃ gearbox oil for 1000 hours without cracking (traditional water-blocking tapes expand and fail after immersion). It can withstand vibration of 10-2000Hz without loosening (traditional water-blocking tapes have a vibration loosening rate of ≥15% / year). It is fully adaptable to the extreme environment of high temperature, oil stains and vibration of gearboxes, with improved environmental tolerance and extended cable service life.

[0036] Eliminating the need for additional water-blocking structures significantly reduces size: No need for traditional water-blocking tape wrapping or thickened insulation layers; conductor nominal cross-sectional area is 0.5mm². 2 1.8mm, suitable for the miniaturization and high-density wiring requirements of transmission electronic control modules, saving wiring space; and reducing cable weight. Overall lower diameter ≤ This invention also provides a method for preparing an anti-siphon XL-PVDF insulated wire for automotive transmissions, comprising the anti-siphon XL-PVDF insulated wire for automotive transmissions as described in any one of the above embodiments; and the following steps: S1. Conductor sealing: 19 copper wires of 0.19mm are twisted together using a stranding device, and liquid waterproof adhesive is injected at the twisting point to allow the adhesive to fully penetrate and cure, forming a dense sealed conductor. S2. Insulation extrusion: PVDF insulation material is fed into an extruder, heated and melted, and then extruded onto the sealant conductor obtained in step S1. S3. Air cooling: The extruded wire core is passed through a cooling tank and naturally cooled and shaped by air to ensure that the stress of the insulation layer is fully released, and then it is wound into a coil. S4. Irradiation crosslinking: The cooled cable is irradiated through an electron accelerator to crosslink the PVDF molecular chains and obtain the final XL-PVDF insulation layer.

[0037] In one embodiment of the present invention, in S1, 19 tin-plated copper wires with a diameter of 0.19 mm are used, with a stranding pitch of 15 times the diameter, and high-temperature resistant silicone-based waterproof adhesive is injected simultaneously during stranding.

[0038] In one embodiment of the present invention, in S2, a vacuum of -0.06 MPa to -0.08 MPa is applied to the die head area during extrusion to remove air gaps and moisture present at the interface between the insulation layer and the conductor.

[0039] In one embodiment of the present invention, in S2, a 40-type single-screw extruder is used; the temperature zones are set as follows: zone 1 220°C, zone 2 240°C, zone 3 250°C, die head 260°C, and die opening 270°C; the die head is equipped with a honeycomb plate and no filter screen is added.

[0040] In one embodiment of the invention, in S4, the cooled cable is irradiated at a dose of 8-12 Mrad.

[0041] The process of wrapping the water-blocking tape is eliminated, reducing the manufacturing process from five steps to four, thus improving production efficiency. At the same time, the XL-PVDF insulation layer does not require the addition of flame retardants, reducing material costs and overall production costs.

[0042] Vacuum extrusion + meshless filtration eliminates potential quality risks: Vacuum extraction at the die head removes interfacial air gaps (air gap rate ≤ 0.1%), avoiding the siphon channel caused by air gaps in traditional extrusion; the meshless design reduces melt pressure fluctuations (fluctuation ≤ 0.5MPa), insulation layer wall thickness deviation ≤ ±0.02mm, and improves batch-to-batch performance consistency.

[0043] The entire process is solvent-free (silicone-based waterproof adhesive cures at room temperature with no VOC emissions), and the XL-PVDF material is recyclable (recycling rate ≥90%). It also eliminates the risk of traditional grease dripping and contaminating the transmission fluid, ensuring the cleanliness of the transmission electronic control system.

[0044] By adjusting the number and diameter of copper wires, wires with a diameter of 0.12-2.5mm can be produced. 2 Adjustable within the range of 0.15-0.3mm to meet different insulation strength requirements. Cables of different cross-sectional areas are available to adapt to connection scenarios with different current requirements, such as sensors and actuators within gearboxes; insulation layer thickness can be adjusted. In addition to automotive transmissions, it can be extended to similar extreme scenarios such as new energy vehicle motor controllers (150℃ high temperature) and industrial gearboxes (oil-contaminated environment), and its anti-siphon and environmental resistance performance can meet the requirements.

[0045] The working principle of the anti-siphon XL-PVDF insulated wire used in this automotive transmission: Anti-siphon mechanism, dual barriers work together to block First barrier: Conductor sealant blocks microscopic penetration. If fluids such as oil and condensation in the gearbox come into contact with the cable ends, they will first be blocked by the sealant conductor. The silicone-based waterproof adhesive between the copper wires has completely filled all the 3-5μm micro gaps, forming a dense colloidal barrier. The liquid cannot penetrate back along the gaps between the copper wires (no penetration when the penetration pressure is ≤0.1MPa). Moreover, the silicone-based waterproof adhesive does not volatilize or shrink at a high temperature of 150℃, and remains in a filled state for a long time, avoiding the formation of penetration channels after traditional grease dries.

[0046] Secondary barrier: Insulation layer and interface fusion block macroscopic penetration. If a small amount of liquid breaches the first barrier (in extreme cases, such as when the conductor end is damaged), it will contact the inner wall of the insulation layer. The XL-PVDF insulation layer has no interfacial air gap after vacuum extrusion and is slightly fused with the sealant conductor interface, preventing the liquid from forming a continuous penetration path at the interface. At the same time, the XL-PVDF insulation layer itself has an extremely low liquid permeability (transmission oil permeability ≤0.1g / (m・24h) at 150℃), further preventing longitudinal liquid penetration. The synergistic effect of the dual barriers results in an average liquid penetration distance of only 2.5mm in the anti-siphon test (far below the industry requirement of ≤5mm).

[0047] Extreme environment adaptation mechanism (high temperature resistance, oil resistance, vibration resistance) High temperature resistance mechanism After being irradiated with 10Mrad, the XL-PVDF insulation layer forms a three-dimensional network structure, and there is no thermal deformation under long-term use at 150℃ (thermal shrinkage rate ≤1% / 150℃×1h); the silicone-based waterproof adhesive has a glass transition temperature ≥180℃ at 150℃, without softening or dripping, ensuring that the conductor gaps are always filled and the anti-siphon performance does not fail - solving the core pain point of traditional waterproof grease volatilization failure at 150℃.

[0048] Oil resistance and chemical compatibility mechanism XL-PVDF resin itself has excellent oil resistance (after immersion in 150℃ transmission oil for 1000h, the volume change rate is ≤5% and the weight change rate is ≤3%), and it does not chemically react with silicone-based waterproof adhesives or tin-plated copper wires; after immersion, the insulation layer does not crack or swell, and the adhesion between the conductor and the insulation layer is ≥8N / 25mm, ensuring long-term stability in media such as transmission oil and brake fluid.

[0049] Vibration resistance mechanism 19 strands of tin-plated soft copper wire (bending fatigue life ≥10) 6 The cable's flexibility (elongation at break ≥200%), combined with its φ10mm bending radius and XL-PVDF insulation layer, allows it to withstand gearbox vibrations of 10-2000Hz (acceleration ≤50m / s²). 25N / 25mm, no peeling under vibration, avoiding the risk of loosening of traditional water-blocking tapes, and improving long-term reliability by 80%. Meanwhile, the adhesion between the silicone-based waterproof adhesive and the copper wire is ≥ First anti-siphon barrier Nineteen high-purity tin-plated soft copper wires (purity ≥99.95%, tin plating thickness 5-8μm, corrosion resistance ≥5000 hours) with a diameter of 0.19mm are used. They are stranded together with a stranding device at a stranding pitch of 15 times the diameter (stretching pitch = 15 × conductor outer diameter, conductor outer diameter φ1.0mm) to ensure that uniform micro gaps (gap width 3-5μm) are formed between the copper wires. This ensures the flexibility of the conductor (bending radius ≤5mm, suitable for the narrow installation space of the gearbox) and provides a channel for the waterproof adhesive to penetrate.

[0050] Waterproof Adhesive Selection and Filling Process: High-temperature resistant silicone-based waterproof adhesive (model SG-800, solid content ≥98%, viscosity 5000-8000 mPa・s at 25℃) is selected. It is injected into the gaps during the copper wire stranding process using a synchronous injection device on the stranding equipment (injection pressure 0.3-0.5 MPa, injection volume 0.15 g / m). After injection, it is cured at room temperature for 25℃×24h. The adhesive completely fills all micro-gaps (100% filling rate), forming a dense "copper wire-adhesive" composite structure, blocking the primary path of liquid penetration along the conductor gaps. Unlike traditional waterproof sealant (filling rate ≤85%, easily volatile at 150℃), this silicone-based waterproof adhesive has a volume shrinkage rate ≤2% under long-term use at 150℃, with no dripping or evaporation, and an adhesion to the copper wire ≥5N / 25mm, with no risk of peeling under vibration.

[0051] Secondary anti-siphon barrier The resin selected is XL-PVDF resin from Arkema, France (model 5000HG, melting point 165-170℃, volume resistivity ≥1×10⁻⁶). 16 After being cross-linked by electron beam irradiation, a three-dimensional network molecular structure is formed, increasing the rated long-term operating temperature of the insulation layer to 150℃ (compared to only 120℃ for traditional PVDF). After 150℃×3000h heat aging, the tensile strength retention rate is ≥80%, and the elongation at break retention rate is ≥70%, making it perfectly suited for the high-temperature environment of gearboxes. Ω・ Insulation extrusion process: A 40-type single screw extruder (length-to-diameter ratio 25:1) is used, with precise temperature control in the following zones: Zone 1 220℃ (resin preheating), Zone 2 240℃ (melting and plasticizing), Zone 3 250℃ (homogenization), Die head 260℃ (pressure stabilization), and Die opening 270℃ (forming). The key points are: ① Applying a vacuum of -0.07MPa to the die head mold area to remove air gaps (air gap volume ≤0.1%) and trace amounts of moisture (moisture content ≤50ppm) at the interface between the insulation layer and the sealant conductor, thus preventing the formation of siphon channels at the interface; ② Only a honeycomb plate (filtration accuracy 50μm) is installed inside the die head, without a filter screen, reducing melt pressure fluctuations (pressure fluctuation ≤0.5MPa), ensuring uniform insulation layer wall thickness, and finally achieving a nominal outer diameter of 1.72mm (tolerance ±0.05mm) for the insulation layer, meeting the miniaturization requirements of gearbox cables and reducing the outer diameter compared to traditional cables with water-blocking strips.

[0052] Interface filling optimization: During the extrusion process of the insulation layer, the fluidity of the PVDF melt (melt index 10-15 g / 10 min at 260℃) is utilized to ensure a tight fit between the inner wall of the insulation layer and the surface of the sealant conductor (fitting gap ≤ 1 μm). At the same time, the trace amount of silicone-based waterproof adhesive that seeps out (seepage amount ≤ 0.05 g / m) and slightly fuses with the PVDF melt, further eliminating the interface gap and forming a continuous anti-siphon structure of "conductor sealant - interface fusion - insulation layer". The double barrier works together to block liquid penetration.

[0053] Cooling: After the wire core is extruded, it enters a 25-meter-long air cooling tank for room temperature air cooling.

[0054] Irradiation: Irradiation was carried out using an electron accelerator, with the total absorbed dose controlled at 10.0 Mrad.

[0055] Performance results: After heat aging at 150℃ for 3000 hours: no cracking during winding, and no breakdown after 1kV withstand voltage test for 1 minute.

[0056] o Liquid compatibility test: After immersion in media such as transmission oil at 150℃ for 1000 hours, the insulation showed no cracking.

[0057] In the anti-siphon test, after being placed in an environment of 175℃ for 48 hours, the average penetration distance was 2.5mm.

[0058] Passed three core validations: Long-term thermal aging test: After 3000 hours of aging at 150℃, the retention rate of insulation mechanical properties meets the standard.

[0059] Liquid compatibility test: After immersion in media such as transmission oil at 150°C for 1000 hours, the material properties remained stable.

[0060] Anti-siphon test: After treatment at 175℃ for 48 hours, the longitudinal penetration distance of the liquid is less than 5mm.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A type of anti-siphon XL-PVDF insulated wire for automotive gearboxes, characterized in that, include The sealing conductor is made of multiple copper wires twisted together, and the gaps between the twists are filled with waterproof adhesive. The waterproof adhesive completely fills the microscopic gaps between all the copper wires, forming the first anti-siphon barrier. An insulating layer is provided, which tightly covers the outside of the encapsulated conductor, and waterproof silicone is filled between the inner wall of the insulating layer and the encapsulated conductor.

2. The anti-siphon XL-PVDF insulated wire for automotive gearboxes according to claim 1, characterized in that, The sealing conductor is made of 19 strands of soft copper wire, and the waterproof adhesive is a silicone-based waterproof adhesive.

3. The anti-siphon XL-PVDF insulated wire for automotive gearboxes according to claim 2, characterized in that, Each of the aforementioned soft copper wires has a diameter of 0.19 mm and a nominal cross-sectional area of ​​0.5 mm². 2 .

4. The anti-siphon XL-PVDF insulated wire for automotive gearboxes according to claim 1, characterized in that, The insulating layer is an irradiated cross-linked polyvinylidene fluoride layer; the insulating layer is subjected to electron beam irradiation cross-linking treatment to achieve a rated temperature of 150°C.

5. The anti-siphon XL-PVDF insulated wire for automotive gearboxes according to claim 1, characterized in that, The nominal outer diameter of the insulating layer is 1.72 mm and the thickness is 0.19 mm.

6. A method for preparing an anti-siphon XL-PVDF insulated wire for automotive transmissions, characterized in that, include The anti-siphon XL-PVDF insulated wire for automotive transmissions as described in any one of claims 1-5; and the following steps: S1. Conductor sealing: 19 copper wires of 0.19mm are twisted together using a stranding device, and liquid waterproof adhesive is injected at the twisting point to allow the adhesive to fully penetrate and cure, forming a dense sealed conductor. S2. Insulation extrusion: PVDF insulation material is fed into an extruder, heated and melted, and then extruded onto the sealant conductor obtained in step S1. S3. Air cooling: The extruded wire core is passed through a cooling tank and naturally cooled and shaped by air to ensure that the stress of the insulation layer is fully released, and then it is wound into a coil. S4. Irradiation crosslinking: The cooled cable is irradiated through an electron accelerator to crosslink the PVDF molecular chains and obtain the final XL-PVDF insulation layer.

7. The method for preparing an anti-siphon XL-PVDF insulated wire for automotive gearboxes according to claim 6, characterized in that, In S1, 19 tin-plated copper wires with a diameter of 0.19mm are used, with a stranding pitch of 15 times the diameter. High-temperature resistant silicone-based waterproof adhesive is injected simultaneously during stranding.

8. The method for preparing an anti-siphon XL-PVDF insulated wire for automotive gearboxes according to claim 6, characterized in that, In S2, a vacuum of -0.06MPa to -0.08MPa is applied to the die head area during extrusion to remove air gaps and moisture present at the interface between the insulation layer and the conductor.

9. The method for preparing an anti-siphon XL-PVDF insulated wire for automotive gearboxes according to claim 6, characterized in that, In S2, a 40-type single-screw extruder is used; temperature zone settings: zone 1 220℃, zone 2 240℃, zone 3 250℃, die head 260℃, and die orifice 270℃; the die head is equipped with a honeycomb plate and no filter screen is added.

10. The method for preparing an anti-siphon XL-PVDF insulated wire for an automotive transmission according to claim 6, characterized in that, In S4, the cooled cable is irradiated with a dose of 8-12 Mrad.