A kind of anti-leakage sealing method of electric vehicle motor multi-core wire harness

Abstract

The application discloses a kind of anti-leakage sealing methods of electric vehicle motor multi-core wire harness, to the end of wire harness terminal, using negative pressure device or high pressure glue gun fills glue, make sealing glue fill wire harness internal gap, to prevent wire harness siphon penetration.The application compared with the mainstream single wire full line pre-coated glue anti-siphon cable scheme, equipment investment, glue consumables, wire harness procurement cost is greatly reduced, production yield is higher, long-acting sealing performance is more stable, production is flexible, equipment investment is low, sealing durability is significantly superior to traditional only outside coating scheme.

Description

Technical Field

[0001] This invention relates to the field of sealing processing of electric vehicle motor wiring harnesses, and specifically to a leak-proof sealing method for multi-core wiring harnesses of electric vehicle motors. Background Technology

[0002] Electric two-wheeled vehicles widely use integrated composite wiring harnesses for their mid-drive motors and hub motors. The wiring harness contains three or more power phase wires and five or more Hall signal wires. Each phase wire and Hall signal wire is individually wrapped with a thin layer of Teflon insulation. After all the cables are gathered together, they are uniformly wrapped with a thicker PVC or silicone sheath. The wiring harness naturally has two independent capillary gaps: the first gap is the annular gap between the inner surface of the outer PVC / silicone sheath and the outer wall of the multiple independent Teflon cables inside; the second gap is formed by dozens of fine copper wires twisted together inside each phase wire and Hall signal wire, and there are micron-level micro-capillary channels between the individual copper wires. The two layers of gaps are interconnected, and different failures occur in air-cooled and oil-cooled motors. Among them, the leakage defect of the air-cooled motor is that the motor heats up during continuous operation and cools down rapidly after shutdown, creating a negative pressure inside the motor cavity. External rainwater and humid air are drawn into the cavity through the negative pressure along the capillary gaps between the two layers of the wiring harness. Water vapor condenses on the inner wall of the cavity, Hall element, and the surface of the winding copper wire, forming water droplets. Over time, this causes metal corrosion, short circuit damage to the Hall signal, and winding insulation breakdown, rendering the motor unusable. Traditional methods only apply glue to the outer surface of the wiring harness to seal the external interface of the sheath, which cannot penetrate into the capillary gaps between the two layers. Water still enters and condenses after alternating hot and cold temperatures. The leakage defect of oil-cooled motors is that when gear oil and cooling lubricating oil are added to the inside of the motor cavity, the oil in the cavity will continuously seep outward along the gap between the two layers of the wiring harness due to the capillary effect, resulting in insufficient oil in the motor, reduced heat dissipation, and oil contamination of the entire vehicle. Conventional external sealant only blocks the first layer of gap outside the sheath, and cannot seal the capillary channels inside the copper wire and the second layer of gap, resulting in continuous oil leakage during long-term operation.

[0003] The current mainstream anti-siphon cable technology falls into two categories, both with significant shortcomings. The first category is prefabricated, fully sealed anti-siphon special cables, which is currently the mainstream long-term anti-siphon technology. The core structure of this approach involves pre-coating each individual fine copper wire with sealant before the conductor stranding process, then stranding the sealant-coated copper wires into a conductor. The sealant layer on the surface of the entire copper wire blocks capillary siphon channels. However, this prefabricated cable solution has several drawbacks: firstly, the production cost is extremely high, as each individual copper wire requires separate sealant coating equipment, necessitating investment in a complete production line for copper wire pre-coating, drying, and cooling; secondly, the amount of adhesive consumed per kilometer of cable increases significantly, raising raw material costs by 40%. The above points highlight several issues: First, the copper wire becomes sticky after pre-coating, leading to adhesion and breakage during stranding, thus reducing production yield. Second, the cables have poor versatility. While the cables are fully sealed at the factory, cutting, stripping, and welding during motor production damage the end seal layer, requiring secondary glue application after welding, resulting in repetitive processes. The 5-10mm local sealing length cannot be flexibly adjusted according to the motor model, and full-core glue application leads to significant glue waste. Third, material compatibility is limited. The pre-coated copper wire surface is in long-term contact with Teflon and PVC sheaths, and the interface is prone to delamination after high and low temperature cycles. During cable bending, the adhesive layer on the surface of individual filaments is prone to cracking, capillary channels reform, and the anti-siphon function fails. Fourth, production line upgrades are difficult. Wire harness manufacturers need to add dedicated coating and stranding equipment, which small and medium-sized motor manufacturers cannot process independently, forcing them to purchase pre-made special cables, resulting in long supply chain cycles and high inventory pressure.

[0004] The second category is the sealing process at the rear end of the motor assembly. Existing negative pressure potting processes have significant drawbacks. Conventional vacuum potting requires both ends of the wiring harness to be completely sealed to form a closed cavity before a high vacuum can be created. However, during motor wiring harness assembly, one end needs exposed wiring, making it impossible to seal both ends and create a complete vacuum environment. Current solutions require vacuuming first and then disconnecting the vacuum connection to the glue container, which is incompatible with the actual processing conditions of motor wiring harnesses. Furthermore, traditional wiring harness sealing production processes have shortcomings. If liquid water droplets or stains remain on the surface after welding the wiring harness to the stator, direct application of glue will cause the glue to trap moisture, resulting in bubbles and leakage channels after curing. Conventional industry processes lack specific water stain control, leading to a high defect rate. Moreover, existing sealing materials are limited to a single epoxy resin, resulting in a narrow material selection range. The viscosity range is not reasonably set, making it unable to simultaneously adapt to both deep negative pressure penetration and end-face fixed-point sealing processing modes. Some processes only adapt to a fixed number of phase lines and Hall effect lines, resulting in poor versatility. Additionally, existing processes do not differentiate between deep filling and simple end-face sealing conditions, leading to insufficient process adaptability. Summary of the Invention

[0005] The purpose of this invention is to provide a leak-proof sealing method for multi-core wire harnesses in electric vehicle motors, applicable to various types of motors including air-cooled and oil-cooled motors. It solves the problems of existing prefabricated single-wire pre-coated anti-siphon cables, which are expensive and have poor versatility, as well as the shortcomings of the motor rear end sealing process, which only applies external glue and cannot fill the double-layer capillary gap, conventional vacuum potting is not suitable for wire harness structures with one exposed end, has a narrow selection of sealing materials, causes sealing failure due to water accumulation on the surface after wire harness welding, and cannot simultaneously adapt to both air-cooled water absorption and oil-cooled siphon oil leakage faults.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A leak-proof sealing method for multi-core wiring harnesses in electric vehicle motors, comprising the following specific steps.

[0008] S1, Pre-processing of the wiring harness terminals of the multi-core wire harness; Welding the phase wires and Hall signal wires of the wiring harness terminals to the motor stator; Cleaning the wiring harness terminals and welding joints; Peeling off the outer PVC / silicone sheath of the wiring harness terminals to expose multiple phase wires and Hall signal wires with Teflon outer sheaths inside;

[0009] S2, sealing and injection; use negative pressure injection or high-pressure glue gun injection; the viscosity of the sealant at 25℃ is 1000~8000mPa・s;

[0010] Negative pressure gluing first involves sealing and clamping the multi-core wire harness, then connecting the free end of the wire harness to an airtight fixture to achieve an airtight seal. The wire harness terminals are exposed, and a semi-closed chamber is formed inside the airtight fixture, which is connected to a vacuum pump. Then, the vacuum pump is started to continuously evacuate the airtight fixture, creating a relative negative pressure inside, resulting in a pressure difference between the free end of the wire harness and the external atmospheric pressure. At the same time, a glue gun applies sealant to the gaps in the wire harness sheath and the welding positions of the wire cores at the wire harness terminals. The suction force created by the pressure difference causes the sealant to penetrate into the gaps inside the wire harness.

[0011] High-pressure glue gun injection involves using a high-pressure glue gun to apply pressure to the exposed part of the wire harness terminal and apply glue. The sealant penetrates into the gaps inside the wire harness and completely covers the exposed copper wire and outer sheath joint of the wire harness terminal, achieving end sealing and waterproofing.

[0012] Use negative pressure glue injection or high pressure glue gun to inject glue. After the multi-core wire harness is injected, let it stand at room temperature for 1 to 3 minutes to remove the tiny air bubbles trapped inside the glue.

[0013] S3, normal pressure curing molding; for those using negative pressure injection, turn off the vacuum pump, remove the airtight tooling and glue gun, and cure the multi-core wire harness at room temperature for at least 4 hours, or bake at 60°C for 30 minutes.

[0014] For multi-core wire harnesses that are glue-injected using a high-pressure glue gun, curing is carried out at room temperature for at least 4 hours after glue injection is completed;

[0015] S4, sealing inspection; a leak-free inspection is performed using negative pressure, or an air tightness inspection is carried out.

[0016] In step S1, metal debris and floating dust on the surfaces of the wire harness connection end and the welded joint are cleaned, so that there are no visible liquid water droplets or continuous water stains on the surfaces of the wire harness connection end and the welded joint.

[0017] In step S2, negative pressure glue injection is adopted, and the filling length of the sealant that penetrates into the internal gaps of the wire harness is 5mm to 10mm.

[0018] The sealant is an oil-resistant insulating adhesive, which is prepared and mixed from an epoxy resin matrix and a polyamide curing agent at a mass ratio of 3.8 to 4.2:1.

[0019] The oil-resistant insulating adhesive is prepared and mixed from an epoxy resin matrix and a polyamide curing agent at a mass ratio of 4:1, and the viscosity of the oil-resistant insulating adhesive at 25°C is 3200 mPa·s.

[0020] The leak-free inspection in step S4 is performed by immersing the wire harness connection end in colored gear oil, applying a negative pressure of 0.05 MPa to the free end of the wire harness for 30 seconds, then letting it stand for 72 hours. If no gear oil seeps out from the free end of the wire harness, the sealing is determined to be qualified.

[0021] The air tightness inspection in step S4 is performed after the motor is completely installed and the left and right end covers are locked; the quick connector of the air tightness inspection equipment is connected to the threaded hole of the motor end cover, the air tightness inspection equipment is started to fill the interior of the motor with dry gas of 20kPa±2, with gas charging for 10S, pressure stabilization for 5S, and inspection for 8S. During the inspection process, if the leakage rate is less than 2Pa / s, it is judged as qualified.

[0022] In view of the above technical features, the present invention has the following beneficial effects: 1. The present invention covers all air-cooled and oil-cooled motors, and is compatible with the double-layer gap composite wire harness of the mid-mounted and hub motors of two-wheeled vehicles; it eliminates the separate drying process of the wire harness, and after the wire harness is welded to the stator, only debris needs to be cleaned and the surface needs to be kept dry; it eliminates the need to pre-apply glue to each copper wire during the wire harness production stage, and only seals a 5-10mm local area of ​​the wire harness connection end at the motor assembly end, which greatly reduces the cost of equipment and glue consumables; 2. The present invention is applicable to all types of motors and simultaneously solves two types of leakage faults: it can seal the double-layer capillary channels of oil-cooled motors to block the siphon leakage of lubricating oil; and it can eliminate the hot and cold negative pressure water absorption channels of air-cooled motors. One process is suitable for all air-cooled and oil-cooled motors; 3. The vacuum-synchronized glue dispensing process in the present invention relies on the negative pressure suction force combined with the vacuuming time and negative pressure intensity to precisely control the glue liquid 5-10mm. Deeply penetrates, completely filling both capillary gaps, suitable for the harsh working conditions of long-term anti-siphon oil leakage in oil-cooled motors, and stably achieves a high waterproof rating of IP67; the high-pressure glue gun end-face sealing process does not require vacuum equipment, only applying glue at the exposed end of the wire harness, focusing on sealing the outer skin seams and welding exposed copper wires, with simple procedures and high changeover efficiency, suitable for simple waterproofing and small-batch repair processing scenarios for air-cooled motors; 4. The sealant of this invention has a wide selection range, and the viscosity range has complete industry engineering basis. The sealant is an oil-resistant insulating adhesive with a viscosity limited to 1000-8000 mPa·s (tested under 25℃ conditions); the lower limit of 1000 mPa·s avoids the problems of low-viscosity adhesive sagging, unrestricted seepage, and long-term high-temperature oil immersion delamination, while the upper limit of 8000 mPa·s The adhesive can penetrate micron-level copper wires and double-layer capillary gaps in the sheath using a semi-closed, single-sided negative pressure. This viscosity range fully covers the mainstream specifications of sealants for automotive flat wire stator ends and electric vehicle motor harnesses. The adhesive has moderate fluidity, balancing deep negative pressure penetration with high-pressure glue gun point sealing. During the settling process, it can autonomously precipitate and encapsulate air bubbles. The cured adhesive layer can withstand long-term immersion in 150°C high-temperature gear oil and cooling oil for 2000 hours without swelling, delamination, or interface peeling. All process parameters of this invention are standardized and controllable, achieving a batch production sealing yield of over 99.5%. A supporting negative pressure oil immersion leak detection process allows for batch screening of poorly sealed harnesses, reducing after-sales problems such as rust and oil leaks after motors leave the factory. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the invention using an airtight tooling for glue filling.

[0024] In the diagram: 1 - Multi-core wire harness; 11 - Wire harness terminal; 12 - Wire harness free end; 2 - Motor stator; 3 - Airtight fixture; 4 - Vacuum pump. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these drawings and embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that some components well-known to those skilled in the art but not related to the main content of the present invention may be omitted in the drawings or description. Additionally, for ease of description, some components in the drawings may be omitted, enlarged, or reduced, but this does not represent the actual size or complete structure of the product.

[0026] This invention is applicable to various types of motors, including air-cooled motors and oil-cooled motors. Integrated composite wiring harnesses are widely used in mid-drive motors and hub motors of electric two-wheeled vehicles. The multi-core wiring harness 1 contains three or more power phase wires and five or more Hall effect signal wires. Each phase wire and Hall effect signal wire is individually wrapped with a thin layer of Teflon insulation. After all the cables are gathered together, they are uniformly wrapped with a thicker PVC or silicone sheath. The multi-core wiring harness 1 naturally has two independent capillary gaps: the first gap is the annular gap between the inner surface of the outer PVC / silicone sheath and the outer wall of the multiple independent Teflon cables inside; the second gap is formed by dozens of fine copper wires twisted together inside each phase wire and Hall effect signal wire, with micron-level micro-capillary channels existing between the individual copper wires. The two layers of gaps are interconnected. The air-cooled and oil-cooled motors have different failures. The air-cooled motor's alternating hot and cold temperatures create a pressure difference between the inside and outside of the cavity. Moisture is drawn in along the wire harness gaps, condenses and corrodes the copper wires and Hall sensors. The oil-cooled motor relies on capillary action to leak the cooling lubricating oil from the cavity to the outside.

[0027] This invention provides a leak-proof sealing method for multi-core wiring harnesses in electric vehicle motors, simultaneously addressing the differentiated leakage defects of two types of motors, such as... Figure 1 As shown, the specific steps are as follows:

[0028] S1, Pre-processing of the wiring harness terminal 11 of the multi-core wire harness 1; Welding the phase wire and Hall signal wire of the wiring harness terminal 11 to the motor stator 2; Cleaning the wiring harness terminal 11 and the welded joint.

[0029] Furthermore, metal shavings and dust should be cleaned from the wire harness terminals 11 and the surface of the welding joints to ensure that there are no visible liquid water droplets or continuous water stains on the surface of the wire harness terminals 11 and the welding joints. Peel off the outer PVC / silicone sheath of the wire harness terminals 11 to expose multiple phase wires and Hall signal wires with Teflon outer sheaths inside.

[0030] S2, sealing and injection; negative pressure injection or high-pressure glue gun injection can be used;

[0031] Negative pressure gluing involves sealing and clamping the multi-core wire harness 1; connecting the free end 12 of the wire harness to the airtight fixture 3 to achieve an airtight seal, with the wire harness connection end 11 exposed, forming a semi-closed chamber inside the airtight fixture 3, which is connected to a vacuum pump 4; then, starting the vacuum pump 4 to continuously evacuate the airtight fixture 3, creating a relative negative pressure inside, resulting in a pressure difference between the free end 12 of the wire harness and the external atmospheric pressure; simultaneously, applying sealant to the gaps in the wire harness sheath and the welding positions of the wire cores at the connection end 11 of the wire harness using a glue gun, with the suction force generated by the pressure difference causing the sealant to penetrate into the gaps inside the wire harness; preferably, the filling length of the sealant penetrating into the gaps inside the wire harness is precisely controlled to be 5mm to 10mm by relying on the pressure difference suction.

[0032] High-pressure glue gun injection involves using a high-pressure glue gun to apply pressure to the exposed portion of the wire harness terminal 11, allowing the sealant to penetrate into the gaps inside the wire harness. Since high-pressure glue gun injection results in a shorter length of sealant entering the gaps inside the wire harness compared to negative pressure injection, to ensure a good seal, the sealant must completely cover the exposed copper wire and outer sheath joint of the wire harness terminal 12 to achieve end sealing and waterproofing.

[0033] The sealant used for injection is an oil-resistant insulating adhesive, including at least one of epoxy, polyurethane, and silicone. The viscosity of the sealant at 25°C is 1000–8000 mPa·s.

[0034] A viscosity limit of 1000 mPa·s is used to avoid problems such as low-viscosity adhesive sagging, unrestricted panelizing, and delamination during long-term high-temperature oil immersion. Adhesives with a viscosity lower than this value have excessive fluidity, making it impossible to accurately control the 5-10 mm filling length during negative pressure adhesive suction, and they are prone to unrestricted penetration into the deep interior of the wire harness, resulting in adhesive waste. At the same time, low-viscosity adhesives have insufficient functional filler content, and are prone to delamination and swelling during long-term high-temperature oil immersion.

[0035] The viscosity limit of 8000 mPa·s ensures that the colloid can penetrate the micron-level capillary gaps of the copper wire and sheath using a semi-closed unilateral negative pressure. This viscosity range fully covers the mainstream specifications of sealants for mass-produced automotive flat wire stator ends and electric vehicle motor wiring harnesses. The colloid has moderate fluidity, balancing deep penetration under negative pressure with targeted sealing by high-pressure glue guns. It can spontaneously precipitate and encapsulate air bubbles during the standing process. The cured adhesive layer can withstand long-term immersion in 150℃ high-temperature gear oil and coolant oil for 2000 hours without swelling, delamination, catalytic decomposition, or interface peeling. The cured adhesive layer adheres firmly to the copper wire, Teflon sheath, and PVC / silicone sheath without peeling or delamination. Beyond this viscosity range, the colloid becomes more like a paste, with insufficient fluidity, and cannot penetrate the micron-level capillary gaps of the copper wire and sheath using only the relative negative pressure created by the unilateral tooling.

[0036] The viscosity range of the sealant is 1000-8000 mPa·s, fully covering the mainstream specifications of general-purpose oil-resistant insulating adhesives for motor wire harnesses / stator ends, including epoxy, polyurethane, and silicone. It is also compatible with the dual processes of vacuum synchronous glue suction and high-pressure glue gun end sealing of this invention. During the static process of the adhesive, air bubbles can be automatically released and encapsulated. After curing, the adhesive layer is dense and stable, and the long-term anti-seepage performance meets the standards.

[0037] Preferably, the oil-resistant insulating adhesive is prepared by mixing an epoxy resin matrix and a polyamide curing agent at a mass ratio of 3.8 to 4.2:1; further, the oil-resistant insulating adhesive is prepared by mixing an epoxy resin matrix and a polyamide curing agent at a mass ratio of 4:1, and the viscosity of the oil-resistant insulating adhesive at 25°C is 3200 mPa·s.

[0038] The industry standard mixing ratio for two-component epoxy adhesive used for sealing electric vehicle motor wiring harnesses and stator ends is 4:1. A range of 3.8 to 4.2:1 is set around the optimal ratio of 4:1, allowing for reasonable fluctuations to accommodate the adhesive mixing needs under fluctuating temperatures throughout the year. The polyamide-modified epoxy system exhibits high bonding strength to copper wire, Teflon, PVC, and silicone, with excellent adhesive toughness and resistance to long-term gear oil immersion. A mixing ratio below 3.8:1 results in excessive curing agent, reduced oil resistance, and easy swelling after prolonged high-temperature oil immersion. A mixing ratio above 4.2:1 results in excessive resin component, incomplete cross-linking of the adhesive, and internal softening after curing, easily leading to leakage channels. The viscosity of the mixed adhesive falls precisely within the 1000–8000 mPa·s range, allowing for simultaneous application of both vacuum adhesive suction and handheld high-pressure glue gun end-face sealing processes.

[0039] After the sealant is filled, let it stand for 1 to 3 minutes to allow any tiny air bubbles trapped inside the sealant to dissipate.

[0040] S3, normal pressure curing molding; for negative pressure injection, turn off vacuum pump 4, remove airtight tooling 3 and glue gun, and let it stand to cure; preferably, the multi-core wire harness 1 is cured at room temperature for at least 4 hours, or baked at 60°C for 30 minutes.

[0041] For multi-core wire harness 1 that is glued using a high-pressure glue gun, the glued multi-core wire harness 1 should be cured at room temperature for at least 4 hours after the glue is applied.

[0042] S4, Sealing test; using negative pressure to perform a leak-free test or an airtightness test.

[0043] For the leak-free test, immerse the wiring harness terminal 11 in colored gear oil, apply a negative pressure of 0.05 MPa to the free end 12 of the wiring harness for 30 seconds, and then let it stand for 72 hours. If no gear oil seeps out from the free end 12 of the wiring harness, the seal is deemed qualified.

[0044] The airtightness test is performed after the motor is installed and the left and right end covers are locked. The quick connector of the airtightness test equipment is connected to the threaded hole of the motor end cover. The airtightness test equipment is started and dry gas of 20 kPa ± 2 is injected into the motor. The gas is injected for 10 seconds, the pressure is stabilized for 5 seconds, and the test is performed for 8 seconds. If the leakage is less than 2 Pa / s during the test, it is considered qualified.

[0045] Example 1 of negative pressure gluing is as follows: A one-meter-long multi-core wire harness 1 is prefabricated by a wire harness manufacturer. The multi-core wire harness 1 includes three power phase wires and six Hall signal wires. The phase wires and Hall signal wires of the wire harness terminal 11 are soldered to the pins of the stator 2 of the hub motor. Metal debris and dust at the joints are cleaned with a brush. It is visually confirmed that there are no visible liquid droplets or continuous water stains in the area to be glued at the wire harness terminal 11. The outer silicone sheath of the wire harness free end 12 is peeled off to expose the inner cable with a Teflon outer sheath. The wire harness free end 12 is installed into the airtight fixture 3 and sealed on one side, forming a semi-closed cavity. The vacuum pump 4 is turned on to continuously pump air to create a relative negative pressure. At the same time, epoxy sealant is applied to the gaps in the wire sheath and the copper wire welding points of the wire harness terminal 11 using a glue gun. The negative pressure and pumping time are adjusted to control the glue filling length to 8mm. The glue is left to stand for 2 minutes to remove tiny air bubbles. It is then baked at 60℃ for 30 minutes to cure, with a curing time of 5~10mm. The two capillary gaps in the section are completely filled with adhesive, and the wire harness is IP67 waterproof. The sealant ratio is epoxy resin:polyamide curing agent = 4:1, with a viscosity of 3200 mPa·s at 25°C. It can withstand continuous immersion in gear oil at 150°C for 2000 hours without swelling or peeling at the interface. After a 72-hour negative pressure leak test, no liquid seepage was observed at the free end 12 of the wire harness, indicating a qualified seal. In this embodiment, only the 8mm section at the end is glued. Compared with the full-core monofilament pre-coating solution, adhesive consumption is reduced by 65%, no special cables are required, and the overall manufacturing cost is reduced by 42%.

[0046] Example 2 of high-pressure glue gun application is as follows: A one-meter-long multi-core wire harness 1 is prefabricated by a wire harness manufacturer. The multi-core wire harness 1 includes three power phase wires and eight Hall effect signal wires. The wire harness terminal 11 is welded to the stator 2 of the central motor. The surface dust is cleaned, and the area to be glued is checked for liquid water stains. The outer PVC sheath of the wire harness terminal 11 is peeled off. A handheld high-pressure glue gun is used to apply pressure to the exposed end of the wire harness terminal 11, and a small amount of sealant is applied to penetrate the wire core to completely seal the gaps in the outer sheath and the exposed copper wires welded to the Hall effect signal. After the glue application is completed, the wire harness is left to stand for 1.5 minutes to remove bubbles, and then left to stand at room temperature for 4 hours. Curing is complete; after the motor is installed and the left and right end caps are locked, an airtightness test is performed; the quick connector of the airtightness testing equipment is connected to the threaded hole of the motor end cap, and the airtightness testing equipment is started to fill the motor with dry gas at 20 kPa ± 2. The filling time is 10 seconds, the pressure is stabilized for 5 seconds, and the test is performed for 8 seconds. During the test, the leakage is less than 2 Pa / s, there is no water absorption or condensation inside the wire harness, and the waterproof performance meets the basic requirements of IP67; the viscosity of the polyurethane sealant used is 4500 mPa・s, and it can withstand immersion in 150℃ cooling oil for 2000 hours without failure. This embodiment does not require the matching airtightness tooling 3, the incremental investment in equipment for small-batch production is extremely low, and the amount of adhesive used is only 30% of that of the full core pre-coating solution.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. All equivalent changes and modifications made within the scope of the claims of this invention should be considered within the technical scope of this invention.

Claims

1. A leak-proof sealing method for a multi-core wiring harness of an electric vehicle motor, characterized in that: The specific steps are as follows: S1, Pre-processing of the wiring harness terminal (11) of the multi-core wire harness (1); Welding of the phase wire and Hall signal wire of the wiring harness terminal (11) to the motor stator (2); Cleaning of the wiring harness terminal (11) and welding joint; Peeling off the outer PVC / silicone sheath of the wiring harness terminal (11) to expose multiple phase wires and Hall signal wires with Teflon outer sheaths inside; S2, sealing and injection; use negative pressure injection or high-pressure glue gun injection; the viscosity of the sealant at 25℃ is 1000~8000mPa・s; The negative pressure gluing process begins by sealing and clamping the multi-core wire harness (1) and connecting the free end (12) of the wire harness to the airtight fixture (3) to achieve airtight sealing. The wire harness connection end (11) is exposed, and a semi-closed chamber is formed inside the airtight fixture (3). The airtight fixture (3) is connected to the vacuum pump (4). Then, the vacuum pump (4) is started to continuously pump air from the airtight fixture (3) to form a relative negative pressure inside the airtight fixture (3), creating a pressure difference between the free end (12) of the wire harness and the external atmospheric pressure. At the same time, the glue gun applies sealant to the gaps in the wire harness outer sheath and the welding position of the wire core at the connection end (11) of the wire harness. The suction force formed by the pressure difference causes the sealant to penetrate into the gaps inside the wire harness. High-pressure glue gun injection is to use a high-pressure glue gun to apply pressure to the exposed part of the wire harness terminal (11) and apply glue. The sealant penetrates into the gap inside the wire harness and completely covers the exposed copper wire and outer sheath joint of the wire harness terminal (11) to achieve end sealing and waterproofing. Use negative pressure glue injection or high pressure glue gun to inject glue. After the glue injection is completed, the multi-core wire harness (1) is left to stand at room temperature for 1 min to 3 min to remove the tiny air bubbles trapped inside the glue. S3, normal pressure curing molding; for negative pressure injection, turn off the vacuum pump (4), remove the airtight tool (3) and glue gun, and cure the multi-core wire harness (1) at room temperature for at least 4 hours, or bake at 60°C for 30 minutes.

2. For multi-core wire harnesses (1) that are glued using a high-pressure glue gun, the glued multi-core wire harnesses (1) shall be cured at room temperature for at least 4 hours after glue application; S4, Sealing test; using negative pressure to perform a leak-free test or an airtightness test.

3. The leak-proof sealing method according to claim 1, characterized in that: In step S1, metal debris and dust are cleaned from the wire harness terminals (11) and the surface of the welding joints, so that there are no visible liquid water droplets or continuous water stains on the wire harness terminals (11) and the surface of the welding joints.

4. The leak-proof sealing method according to claim 1, characterized in that: In step S2, negative pressure is used for injection, and the sealant penetrates into the gaps inside the wire harness, filling a length of 5mm to 10mm.

5. The leak-proof sealing method according to claim 1, characterized in that: The sealant is an oil-resistant and insulating adhesive, which is made by mixing epoxy resin matrix and polyamide curing agent at a mass ratio of 3.8 to 4.2:

1.

6. The leak-proof sealing method according to claim 4, characterized in that: The oil-resistant insulating adhesive is made by mixing epoxy resin matrix and polyamide curing agent at a mass ratio of 4:

1. The viscosity of this oil-resistant insulating adhesive at 25°C is 3200 mPa·s.

7. The leak-proof sealing method according to claim 1, characterized in that: The leak-free test in step S4 involves immersing the wiring harness terminal (11) in colored gear oil, applying a negative pressure of 0.05 MPa to the free end (12) of the wiring harness for 30 seconds, and then letting it stand for 72 hours. If no gear oil leaks from the free end (12) of the wiring harness, the seal is deemed qualified.

8. The leak-proof sealing method according to claim 1, characterized in that: The airtightness test in step S4 is performed after the motor is installed and the left and right end covers are locked. Connect the quick connector of the airtightness test equipment to the threaded hole of the motor end cover, start the airtightness test equipment and charge the motor with 20kPa±2 dry gas. Charge for 10 seconds, stabilize the pressure for 5 seconds, and test for 8 seconds. If the leakage is less than 2Pa / s during the test, it is considered qualified.

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