Long-life special oil for new energy vehicle reduction gearbox and preparation method thereof

Abstract

The application discloses a long-life special oil for new energy vehicle reduction gearbox and a preparation method thereof, and belongs to the technical field of lubricating oil. The special oil for the reduction gearbox comprises the following components in mass percentage: a metal deactivator 1.5-4%, an antioxidant 3-5%, an extreme pressure anti-wear agent 3-5%, a cleaning dispersant 4-7%, a pour point depressant 0.3-1%, a defoaming agent 0.1-0.3%, and the balance is base oil. The technical scheme of the application can consider oil change when the mileage reaches 200,000 km, while the prior art mostly needs oil change when the mileage reaches 40,000 km, 60,000 km or 100,000 km, and the lubricating oil greatly improves the service life of the new energy vehicle reduction gearbox oil. In addition, the application also has excellent low-temperature fluidity and low-temperature starting property, can ensure the smooth starting of the new energy vehicle under the condition of-30 DEG C, and has excellent comprehensive performance.

Description

Technical Field

[0001] This invention belongs to the field of lubricating oil technology, and more specifically, relates to a long-life special oil for gearboxes of new energy vehicles and its preparation method. Background Technology

[0002] Fossil fuels provide 80% of the world's energy needs, and their use pollutes the environment and is a non-renewable resource. Developing new energy vehicles is an important way to achieve dual-carbon goals.

[0003] In new energy vehicles, the driving force of electric vehicles changes from the traditional internal combustion engine to an electric motor, eliminating the need for the internal combustion engine. However, the gearbox (reduction gearbox) remains prevalent. Compared to traditional manual gearboxes, electric drive reducers have a simpler structure, fewer gears, and no need for shifting mechanisms or synchronizers, thus eliminating power interruption losses during gear changes and resulting in higher efficiency. Pure electric vehicle transmission systems, based on motor cooling methods, mainly include water-cooled motors with single-stage reduction gearboxes, oil-cooled motors with single-stage reduction gearboxes, and oil-cooled motors with multi-stage reduction gearboxes. Currently, for single-stage reduction gearboxes in new energy vehicles, traditional 75W viscosity grade GL-4 and GL-5 oils are commonly used. These gear oils have good oxidation characteristics, load-bearing capacity, and shear stability, but tend to accumulate sludge after a period of use, requiring frequent oil changes and having a short lifespan. For multi-stage reduction gearboxes, the oil must balance the copper corrosion and electrochemical performance of oil-cooled motors with gear protection and synchronizer friction performance under high loads and high speeds.

[0004] Compared to gasoline-powered vehicles, the domestic oil market for electric vehicles is currently more complex. The types of oils used in the gearboxes of new energy vehicles are diverse, and many oils develop problems such as sludge, poor cooling, and excessive noise after a period of use or approximately 40,000 kilometers, requiring frequent oil changes. Otherwise, they will accelerate the wear of mechanical parts and affect driving performance. Therefore, it is necessary to design a dedicated lubricant for electric vehicle gearboxes to meet their specific needs.

[0005] A search revealed that Chinese Patent Publication No. CN114317068B discloses a lubricating oil for automobile engines, its preparation method, and its application. This lubricating oil, by weight, comprises the following raw materials: 80-85 parts base oil, 0.5-2 parts composite nanoparticles, 1-5 parts first anti-wear agent, 1-20 parts second anti-wear agent, 0.5-3 parts extreme pressure agent, 6-10 parts viscosity index improver, 0.2-0.4 parts pour point depressant, 0.5-1 part antioxidant, and 0.1-1 part antifoaming agent. The extreme pressure agent includes 2,5-dimercaptothiadiazole zinc salt and vanadium naphthenate. The composite nanoparticles are prepared from 4-ethoxyphenylacetic acid, nano-copper, nano-copper oxide, and nano-copper sulfide. This lubricant, through formula adjustments, can meet the lubrication needs of engines operating intermittently at low temperatures for short periods. It is suitable not only for gasoline vehicles but also for some new energy vehicles. However, its applicable vehicle range is relatively narrow, and its service life still needs to be further improved, making it difficult to meet the needs of long-mileage use. Summary of the Invention

[0006] 1. The problem to be solved

[0007] The purpose of this invention is to overcome the problems of short lifespan and poor overall performance of gearbox oils used in new energy vehicles, and to provide a long-life dedicated gearbox oil for new energy vehicles and its preparation method. The lubricating oil prepared using the technical solution of this invention is specifically designed for use in gearboxes of new energy vehicles, exhibits excellent overall performance, and extends the oil's service life, achieving the goal of not requiring oil changes for up to 200,000 kilometers.

[0008] 2. Technical Solution

[0009] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0010] One objective of this invention is to provide a long-life lubricant specifically designed for new energy vehicle gearboxes. This lubricant is specifically researched and designed for new energy vehicles, as there are currently very few lubricant products in China specifically designed for new energy vehicle gearboxes, and corresponding technical solutions are also rare. The lubricant of this invention comprises the following components by weight percentage: 1.5%-4% metal deactivator, 3%-5% antioxidant, 3%-5% extreme pressure anti-wear agent, 4%-7% detergent-dispersant, 0.3%-1% pour point depressant, 0.1%-0.3% defoamer, with the balance being base oil. By optimizing the types and proportions of the lubricant components, a suitable solution can be effectively provided based on the characteristics of new energy vehicle gearboxes, extending the service life of the gearbox oil.

[0011] This invention, through the selection of base oils and additives, and by studying the compatibility and synergistic effects between components, extends the service life of the resulting lubricating oil, meeting the 200,000-kilometer oil change target, and also improves the low-temperature starting performance of the lubricating oil, promoting the widespread use of new energy vehicles in cold northern regions. Furthermore, the lubricating oil of this invention possesses excellent overall performance, effectively meeting the requirements of new energy vehicle gearboxes.

[0012] Firstly, for gearbox lubricants in new energy vehicles, the issues of lubrication and cooling need to be addressed. Because traditional lubrication and cooling technologies are incompatible, most electric vehicles currently employ two independent systems. This hinders the integration, control, unification, lightweight design, and intelligence of electric vehicles, restricting overall cost reduction and efficiency improvement, and severely impeding their rapid development. However, combining the gearbox, differential lubricant, and motor / electronic component coolant into a single integrated system allows for a compact, integrated design, achieving safety, energy efficiency, and a longer lifespan. Therefore, a specific lubricant is needed that can simultaneously meet both lubrication and cooling requirements.

[0013] The lubricity of an oil refers to its ability to form a protective film on mechanical parts such as gears. Oils with higher viscosity generally have better lubricity, but they are also thicker and have poorer cooling performance. Therefore, the viscosity of the oil should be relatively low while maintaining a certain level of lubricity, and the viscosity should decrease minimally at high temperatures. To this end, as a further improvement of this invention, the selection of the base oil directly affects whether the final lubricating oil can achieve both lubrication and cooling performance. Through extensive experimental research, the applicant has found that selecting a high-oxygen synthetic hydrocarbon base oil as the main component of the blending oil, and more preferably polyalphaolefin (PAO4), is optimal. This type of base oil has the characteristics of high viscosity index and low volatility, while also exhibiting excellent low-temperature performance and superior oxidation stability, ensuring the basic performance of the special oil for the gearboxes of new energy vehicles.

[0014] Furthermore, the blended base oil of this invention creatively incorporates synthetic ester base oil and 150N. The polyalphaolefin (PAO4), synthetic ester base oil, and 150N are blended and used in a controlled mass ratio of 4:(1-2):(1-2). On one hand, this not only effectively improves the solubility of the blended base oil but also enhances its compatibility with other additives, thereby significantly improving the stability of the formulation system. In actual automotive use, this reduces sludge formation, extends the service life of the lubricating oil, and achieves the goal of 200,000 kilometers without oil changes. On the other hand, the specific types of base oils blended in this invention, when used as a blended base oil, exhibit a higher breakdown voltage than single base oils, reaching over 68kV, and possesses better insulation properties.

[0015] As a further improvement of the present invention, the selection criteria for the synthetic ester base oil is: a kinematic viscosity of 18-22 mmHg at 40°C. 2 Between 0.5 m / s, the kinematic viscosity at 100℃ is 4-5.5 mm. 2 The pour point should not exceed -51°C and the flow rate should be between 0.5 and 0.5 seconds. Using this type of synthetic ester base oil effectively meets the formulation requirements of this invention, works synergistically with the other two base oils, and extends the service life of the oil.

[0016] As a further improvement of this invention, in the selection of the metal deactivator, this invention uses molybdenum dialkyldithiocarbamate to enhance the corrosion resistance of the oil, preventing corrosion of metals such as copper and steel. Among traditional metal deactivators, benzotriazole-type metal deactivators are poorly soluble in lubricating oils. However, the lubricating oil made from molybdenum dialkyldithiocarbamate used in this invention can achieve a deactivation effect by forming a passivation layer on the metal surface during use. Furthermore, the oil exhibits strong stability at high temperatures, providing long-term and continuous protection for the metal. Simultaneously, this specific type of metal deactivator can synergistically interact with antioxidants to enhance antioxidant effects; furthermore, it can further improve the breakdown voltage of the resulting oil. After adding the metal deactivator of this invention and compounding it with the base oil, the breakdown voltage of the resulting oil is further improved compared to when it was not added, reaching 75kV, further enhancing the insulation properties of the special oil for new energy vehicle gearboxes.

[0017] As a further improvement of this invention, the antioxidants are N-phenyl-o-aminobenzoic acid, octyl diisooctyl dithiophosphate, and zinc dialkyl dithiophosphate in a mass ratio of 2:(2-3):(1-2). These three additives are generally used as anti-wear agents in gear oils, but in this invention, they primarily function as antioxidants. The three work synergistically; N-phenyl-o-aminobenzoic acid acts as the primary antioxidant by capturing free radicals generated during oil use. The other two substances act as co-antioxidants, decomposing peroxides and, together with metal deactivators, inhibiting oil oxidation through multiple pathways, thereby extending the oil's service life and ultimately achieving the goal of 200,000 kilometers without oil changes.

[0018] As a further improvement of the present invention, diene succinimide or polyisobutylene bis(succinimide) is selected as the detergent-dispersant. The addition of the detergent-dispersant prevents sludge, wear debris, and other substances from adhering to mechanical parts, thereby affecting the lubrication and anti-wear performance of the gearbox oil. Simultaneously, the applicant unexpectedly discovered in experiments that adding this specific type of detergent-dispersant to the lubricating oil components of the present invention can synergistically interact with antioxidants, slowing down the aging rate of the oil and further reducing sludge formation. The applicant speculates that during use, the components of this formulation may interact to form alkylmolybdenum amine complexes, enhancing the detergent-dispersant effect of the oil and further improving its antioxidant properties.

[0019] As a further improvement to this invention, to enhance the extreme pressure anti-wear properties of the special lubricating oil for new energy vehicle gearboxes, especially to ensure that it maintains good extreme pressure anti-wear properties even after long-term use, the applicant initially addressed the extreme pressure anti-wear properties of the oil by increasing the amounts of diisooctyl dithiophosphate and zinc dialkyl dithiophosphate. In addition, dibutyl phosphate and tributyl phosphate were added to the composition. However, it was found that after a period of oxidation and other processes, the extreme pressure anti-wear properties of the oil failed to meet expectations. Furthermore, if sulfur-containing additives were selected in the formulation, corrosion would occur in the copper materials of the motor coils, creating a contradiction between extreme pressure and corrosion. Increasing the content of extreme pressure additives would accelerate the corrosion of metal components by the oil.

[0020] Furthermore, the applicant discovered a contradiction between anti-wear and insulation when conventional extreme pressure anti-wear agents are added to the composition system of this invention. Anti-wear in gears and bearings is achieved by introducing anti-wear agents into the lubrication system. These agents, through their unique polarity, form a physical and chemical adsorption film on the surface of the friction pair, thus providing anti-wear protection. However, the polarity of the anti-wear agent can adversely affect the insulation performance of the lubricating coolant, and may even cause insulation failure, leading to safety issues. Therefore, the applicant continued research and ultimately adopted an unconventional extreme pressure anti-wear agent. Specifically, the extreme pressure anti-wear agent of this invention is composed of an N,P-doped carbon quantum dot solution and nano-calcium carbonate or nano-zirconium dioxide in a molar mass ratio of 2:(1-2).

[0021] The raw materials for the N,P-doped carbon quantum dot solution include sodium citrate and aminotrimethylenephosphonic acid, and its preparation process is as follows:

[0022] Step 1: Sodium citrate and aminotrimethylenephosphonic acid are added to water at a mass ratio of (2-3):1 and stirred until homogeneous. The mixture is then reacted at 190-210℃ for 4-6 hours using the hydrothermal synthesis method to obtain a pale yellow liquid.

[0023] Step 2: Sonicate the above pale yellow liquid for 0.8 to 1.2 hours, and filter it using a 0.2 to 0.24 μm filter membrane to obtain the filtered liquid;

[0024] Step 3: Mix the filtered liquid with diethylene glycol methyl ether at a mass ratio of 1:(2-3), sonicate for 0.8-1.2 h, and finally dehydrate by distillation at 110-130 °C to obtain the N,P doped carbon quantum dot solution to be used.

[0025] Lubricating oils containing the extreme pressure anti-wear agent of this invention exhibit excellent corrosion resistance and insulation properties during use, and maintain good extreme pressure anti-wear properties even after long-term use.

[0026] As a further improvement of this invention, polymethyl methacrylate 602HB is selected as the pour point depressant. Considering the low-temperature fluidity of the special oil for new energy vehicle gearboxes—that is, maintaining good fluidity even at -30℃ in northern regions—a base oil with low viscosity and good low-temperature performance was chosen; in fact, the oil's pour point can reach -57℃. Considering that the performance of the oil inevitably degrades with increasing mileage, and that impurities and waste generated during driving can affect the oil's low-temperature fluidity, a pour point depressant is added in advance to ensure the ultra-long lifespan of the new energy vehicle gearbox oil. Testing shows that the kinematic viscosity of the lubricating oil of this invention increases to 28 mmHg at 40℃ after the vehicle has traveled 200,000 kilometers. 2 / s, the increase is small, the sludge content is small, the acid value increases by 3.41mgKOH / g, and the car can still run normally.

[0027] The second objective of this invention is to provide a method for preparing the aforementioned special oil for the gearbox of new energy vehicles, specifically including the following steps:

[0028] Step 1: Prepare an N,P-doped carbon quantum dot solution, and mix it with nano-calcium carbonate or nano-zirconia at a molar mass ratio of 1:2 to prepare an extreme pressure anti-wear agent for later use;

[0029] Step 2: Blend the base oil; Mix PAO4, synthetic ester base oil and 150N evenly in a mass ratio of 4:(1~2):(1~2);

[0030] Step 3: After heating to 35-45℃, add metal deactivator, antioxidant, detergent dispersant, pour point depressant and defoamer to the blended base oil obtained in Step 2, maintain the above temperature and stir evenly for 0.8-1.2 hours;

[0031] Step 4: Add the extreme pressure anti-wear agent prepared in Step 1 to the mixture obtained in Step 3, stir at 50-70℃ for 1.5-2.5h, and then ultrasonically treat for 0.8-1.2h to obtain the special oil for new energy vehicle gearboxes.

[0032] In summary, this invention, through research on the selection and compatibility of base oils and additives, and supplemented by appropriate preparation process parameters, produces a special oil for the gearbox of new energy vehicles. This oil not only has a long service life, achieving the goal of not needing to change the oil within 200,000 kilometers, but also possesses excellent low-temperature starting performance, ensuring that vehicles can start smoothly in winter temperatures reaching -25°C or even -30°C. This helps new energy vehicles to be widely used in cold northern regions.

[0033] Furthermore, the lubricant formulation of this invention also solves the problems of lubrication and cooling, as well as the contradiction between extreme pressure anti-wear, corrosion resistance, and insulation properties. Finally, based on the gearbox structure of new energy vehicle washing machines, a suitable gearbox oil for new energy vehicles was designed.

[0034] 3. Beneficial effects

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] (1) This invention addresses the gearboxes of new energy vehicles and the future development trend of gearboxes. Based on their characteristics, it designs a long-life special oil for new energy vehicle gearboxes. The technical solution of this invention allows for oil changes only when the mileage reaches 200,000 kilometers, while most existing technologies require oil changes when the mileage reaches 40,000, 60,000, or 100,000 kilometers. The lubricant of this invention greatly improves the lifespan of gearbox oil in new energy vehicles.

[0037] (2) The new energy vehicle gearbox oil of the present invention can ensure that the vehicle can start smoothly at -30℃ in the northern region, that is, it has good low temperature fluidity and low temperature starting performance.

[0038] (3) The special oil for new energy vehicle gearboxes of the present invention has excellent comprehensive performance, mainly in that:

[0039] ① Excellent heat dissipation performance. It ensures that the viscosity of the oil at 100℃ is not too high, maintains the fluidity of the oil at high temperatures, accelerates heat dissipation, and the thermal conductivity measured by experiments is relatively high, reaching 0.19W / m / K.

[0040] ② Excellent electrical properties. The higher the breakdown voltage of the oil, the better its insulation and the more effectively its safety performance is improved. This invention selects blending base oils with high breakdown voltage and further improves the breakdown voltage through the synergistic effect of metal deactivators and antioxidants.

[0041] ③ Excellent oil compatibility. Molybdenum dialkyldithiocarbamate is selected for passivation of metal surfaces to ensure the chemical stability of the oil, avoid wire harness corrosion, and ensure the compatibility of the oil with non-metallic materials such as motor winding insulation varnish, insulation paper, seals, and bushings.

[0042] ④ Excellent antioxidant properties. This invention selects a variety of antioxidants in combination to solve the oxidation problem through multiple pathways. At the same time, it works synergistically with metal deactivators to enhance antioxidant properties, prevent high-temperature oxidation, reduce the formation of sludge and paint film, and reduce changes in the electrical properties of oil after oxidation.

[0043] ⑤ Excellent anti-wear and load-bearing performance. This invention does not choose conventional extreme pressure anti-wear agents, but synthesizes N,P-doped carbon quantum dot solutions and uses them in combination with other nano-additives to resolve the contradiction between extreme pressure and corrosion, as well as the contradiction between anti-wear and electrical performance.

[0044] ⑦ Excellent high-temperature performance. First, select a base oil with a high viscosity index, which can still provide a suitable lubricating film at high temperatures to protect meshing parts. Then, select antioxidants with excellent high-temperature stability to ensure the long-term use of the oil.

[0045] In terms of its overall performance, the new energy vehicle gearbox oil of the present invention is comparable to imported products and can replace imports. However, its manufacturing cost is low and its economic benefits are high compared to using imported oil. Detailed Implementation

[0046] The present invention will be further described below with reference to specific embodiments.

[0047] Example 1

[0048] This embodiment describes a method for preparing a special oil for the gearbox of a new energy vehicle, comprising the following steps:

[0049] S1: Prepare an N,P-doped carbon quantum dot solution, and then combine it with nano-calcium carbonate at a molar mass ratio of 2:1 to form an extreme pressure anti-wear agent for later use;

[0050] S2: Blended base oil. PAO4, synthetic ester-type base oil, and 150N are mixed evenly in a mass ratio of 4:1:1. The kinematic viscosity of the blended base oil at 40°C is 21.58 mm. 2 / s;

[0051] S3: Add 84.4% base oil, 2% metal deactivator, 3% antioxidant, 5% detergent dispersant, 0.5% pour point depressant, and 0.1% defoamer. Heat to 40°C and stir for 1 hour.

[0052] Among them, the metal deactivator is molybdenum dialkyl dithiocarbamate; the antioxidant is N-phenyl-o-aminobenzoic acid, diisooctyl dithiophosphate, and zinc dialkyl dithiophosphate compounded in a mass ratio of 2:2:1; the detergent dispersant is diene succinimide; and the pour point depressant is polymethyl methacrylate 602HB.

[0053] S4: Add 5% extreme pressure anti-wear agent, stir at 60℃ for 2 hours, and ultrasonically treat for 1 hour to obtain a long-life special oil for new energy vehicle gearboxes.

[0054] The obtained long-life new energy vehicle gearbox special oil was tested, and the test results are shown in Table 1.

[0055] Example 2

[0056] This embodiment describes a method for preparing a special oil for the gearbox of a new energy vehicle, comprising the following steps:

[0057] S1: Prepare N,P-doped carbon quantum dot solution, and then combine it with nano-calcium carbonate at a molar mass ratio of 2:1.2 to form an extreme pressure anti-wear agent for later use;

[0058] S2: Blended base oil. PAO4, synthetic ester-type base oil, and 150N are mixed evenly in a mass ratio of 4:1.1:2. The kinematic viscosity of the blended base oil at 40°C is 20.23 mm. 2 / s.

[0059] S3: Add 88.1% base oil, 1.5% metal deactivator, 3% antioxidant, 4% detergent dispersant, 0.3% pour point depressant, and 0.1% defoamer; heat to 35°C and stir for 1.2 hours.

[0060] Among them, the metal deactivator is molybdenum dialkyl dithiocarbamate; the antioxidant is N-phenyl-o-aminobenzoic acid, diisooctyl dithiophosphate, and zinc dialkyl dithiophosphate compounded in a mass ratio of 2:2:1; the detergent dispersant is diene succinimide; and the pour point depressant is polymethyl methacrylate 602HB.

[0061] S4: Add 3% extreme pressure anti-wear agent, stir at 50℃ for 2 hours, and ultrasonically treat for 1.2 hours to obtain a long-life special oil for new energy vehicle gearboxes.

[0062] The obtained long-life new energy vehicle gearbox special oil was tested, and the test results are shown in Table 1.

[0063] Example 3

[0064] This embodiment describes a method for preparing a special oil for the gearbox of a new energy vehicle, comprising the following steps:

[0065] S1: Prepare N,P-doped carbon quantum dot solution, and then combine it with nano-zirconia at a molar mass ratio of 2:1.4 to form an extreme pressure anti-wear agent for later use;

[0066] S2: Blended base oil. PAO4, synthetic ester-type base oil, and 150N are mixed evenly in a mass ratio of 4:2:1. The kinematic viscosity of the blended base oil at 40°C is 20.55 mm.2 / s.

[0067] S3: Add 85.6% base oil, 2.5% metal deactivator, 3.3% antioxidant, 4.5% detergent-dispersant, 0.6% pour point depressant, and 0.2% defoamer; heat to 40℃ and stir for 1.2 hours.

[0068] Among them, the metal deactivator is molybdenum dialkyl dithiocarbamate; the antioxidant is N-phenyl-o-aminobenzoic acid, diisooctyl dithiophosphate, and zinc dialkyl dithiophosphate compounded in a mass ratio of 1:1:1; the detergent dispersant is polyisobutylene bis(succinimide); and the pour point depressant is polymethyl methacrylate 602HB.

[0069] S4: Add 3.3% extreme pressure anti-wear agent, stir at 54℃ for 2.5h, and ultrasonically treat for 1h to obtain a long-life special oil for new energy vehicle gearboxes.

[0070] The obtained long-life new energy vehicle gearbox special oil was tested, and the test results are shown in Table 1.

[0071] Example 4

[0072] This embodiment describes a method for preparing a special oil for the gearbox of a new energy vehicle, comprising the following steps:

[0073] S1: Prepare an N,P-doped carbon quantum dot solution, and then combine it with nano-zirconia at a molar mass ratio of 2:1.5 to form an extreme pressure anti-wear agent for later use;

[0074] S2: Blended base oil. PAO4, synthetic ester-type base oil, and 150N are mixed evenly in a mass ratio of 4:2:1.9. The kinematic viscosity of the blended base oil at 40°C is 21.34 mm. 2 / s.

[0075] S3: Add 82.6% base oil, 3% metal deactivator, 4% antioxidant, 4% extreme pressure anti-wear agent, 5.5% detergent dispersant, 0.7% pour point depressant, and 0.2% defoamer. Heat to 45℃ and stir for 0.8 hours.

[0076] Among them, the metal deactivator is molybdenum dialkyl dithiocarbamate; the antioxidant is N-phenyl-o-aminobenzoic acid, diisooctyl dithiophosphate, and zinc dialkyl dithiophosphate compounded in a mass ratio of 2:3:1; the detergent dispersant is diene succinimide; and the pour point depressant is polymethyl methacrylate 602HB.

[0077] S4: Add 4% extreme pressure anti-wear agent, stir at 63℃ for 1.5h, and ultrasonically treat for 1h to obtain a long-life special oil for new energy vehicle gearboxes.

[0078] The obtained long-life new energy vehicle gearbox special oil was tested, and the test results are shown in Table 1.

[0079] Example 5

[0080] This embodiment describes a method for preparing a special oil for the gearbox of a new energy vehicle, comprising the following steps:

[0081] S1: Prepare N,P-doped carbon quantum dot solution, and then combine it with nano-calcium carbonate at a molar mass ratio of 2:1.8 to form an extreme pressure anti-wear agent for later use;

[0082] S2: Blended base oil. PAO4, synthetic ester-type base oil, and 150N are mixed evenly in a mass ratio of 4:1:1. The kinematic viscosity of the blended base oil at 40℃ is 21.67 mm. 2 / s.

[0083] S3: Add 80.3% base oil, 3.5% metal deactivator, 4.5% antioxidant, 6.2% detergent-dispersant, 0.8% pour point depressant, and 0.2% defoamer; heat to 38°C and stir for 1 hour.

[0084] Among them, the metal deactivator is molybdenum dialkyl dithiocarbamate; the antioxidant is N-phenyl-o-aminobenzoic acid, diisooctyl dithiophosphate, and zinc dialkyl dithiophosphate compounded in a mass ratio of 2:3:1; the detergent dispersant is polyisobutylene bis(succinimide); and the pour point depressant is polymethyl methacrylate 602HB.

[0085] S4: Add 4.5% extreme pressure anti-wear agent, stir at 67℃ for 1.7h, and ultrasonically treat for 1h to obtain a long-life special oil for new energy vehicle gearboxes.

[0086] The obtained long-life new energy vehicle gearbox special oil was tested, and the test results are shown in Table 1.

[0087] Example 6

[0088] This embodiment describes a method for preparing a special oil for the gearbox of a new energy vehicle, comprising the following steps:

[0089] S1: Prepare N,P-doped carbon quantum dot solution, and then combine it with nano-calcium carbonate at a molar mass ratio of 1:1 to form an extreme pressure anti-wear agent for later use;

[0090] S2: Blended base oil. PAO4, synthetic ester-type base oil, and 150N are mixed evenly in a ratio of 4:2:1. The kinematic viscosity of the blended base oil at 40°C is 20.55 mm. 2 / s.

[0091] S3: Add 77.7% base oil, 4% metal deactivator, 5% antioxidant, 7% detergent dispersant, 1% pour point depressant, and 0.3% defoamer; heat to 43℃ and stir for 1.1 hours.

[0092] The metal deactivator is molybdenum dialkyl dithiocarbamate; the antioxidant is a compound of N-phenyl-o-aminobenzoic acid, diisooctyl dithiophosphate, and zinc dialkyl dithiophosphate in a mass ratio of 2:2.1:1.5; the detergent dispersant is polyisobutylene bis(succinimide); and the pour point depressant is polymethyl methacrylate 602HB.

[0093] S4: Add 5% extreme pressure anti-wear agent, stir at 70℃ for 1.5h, and ultrasonically treat for 0.8h to obtain a long-life new energy vehicle gearbox special oil.

[0094] The obtained long-life new energy vehicle gearbox special oil was tested, and the test results are shown in Table 1.

[0095] Comparative Example 1

[0096] The preparation method of a special oil for a new energy vehicle gearbox in this comparative example is basically the same as that in Example 1, except that PAO4 is used as the base oil.

[0097] The obtained special oil for new energy vehicle gearboxes was tested, and the test results are shown in Table 2.

[0098] Comparative Example 2

[0099] The preparation method of a special oil for a new energy vehicle gearbox in this comparative example is basically the same as that in Example 1, except that the metal deactivator used is T551.

[0100] The obtained special oil for new energy vehicle gearboxes was tested, and the test results are shown in Table 3.

[0101] Comparative Example 3

[0102] The preparation method of a special oil for a new energy vehicle gearbox in this comparative example is basically the same as that in Example 1, except that the extreme pressure anti-wear agent used isobutylene sulfide.

[0103] The obtained special oil for new energy vehicle gearboxes was tested, and the test results are shown in Table 4.

[0104] Table 1 shows the test results of the long-life new energy vehicle gearbox special oil obtained in various embodiments of the present invention.

[0105] Table 1 shows the test results of the gearbox-specific oil obtained in each embodiment.

[0106]

[0107]

[0108] As can be seen from the test results of Examples 1-6 in Table 1, the long-life new energy vehicle gearbox oil of this invention has low viscosity and a small viscosity change rate with increasing temperature, proving that the oil has good heat dissipation performance. Simultaneously, the high breakdown voltage proves its good insulation performance. The gearbox oil of this invention causes minimal corrosion to copper sheets; in the experiment, the copper sheets only showed slight discoloration. Regarding oxidation, the rotating oxygen bomb time is long, the acid value change is small, and there is no sludge, ensuring the service life of the gearbox oil. Among the disclosed data, the coefficient of friction is very small, proving that the gearbox oil of this invention has good extreme pressure anti-wear properties.

[0109] Table 2 shows the performance comparison results of the gearbox-specific oils obtained in Comparative Example 1 and Example 1.

[0110] Table 2 shows the performance comparison results of the gearbox-specific oils obtained in Comparative Example 1 and Example 1.

[0111] Breakdown voltage, kV 75 55 GB / T 507 Rotating oxygen bomb (150℃), min 456 401 SH / T 0193

[0112] As shown in Table 2, replacing the base oil with PAO4 altered all properties of the prepared new energy vehicle transmission fluid, with the breakdown voltage showing the most significant change. The decrease in breakdown voltage demonstrates the excellent insulation properties of the blended base oil. The reduction in the rotating oxygen bomb reading indicates better compatibility and pairing between the blended base oil and the additives, ensuring a longer transmission fluid life.

[0113] Table 3 shows the performance comparison results of the gearbox-specific oils obtained in Comparative Example 2 and Example 1.

[0114] Table 3 shows the performance comparison results of the gearbox-specific oils obtained in Comparative Example 2 and Example 1.

[0115]

[0116] Table 3 shows that replacing the metal deactivator resulted in decreased corrosivity of the gearbox oil and a significant decrease in breakdown voltage. This demonstrates that the metal deactivator molybdenum dialkyldithiocarbamate and the antioxidant in the formulation have a synergistic effect, improving breakdown voltage and insulation properties. Replacing the metal deactivator also reduced antioxidant properties, indicating that the metal deactivator molybdenum dialkyldithiocarbamate in the formulation enhances antioxidant effects.

[0117] Table 4 shows the performance comparison results of the gearbox-specific oil obtained in Comparative Example 3 and Example 1.

[0118] Table 4 shows the performance comparison results of the gearbox-specific oils obtained in Comparative Example 3 and Example 1.

[0119]

[0120] As can be seen from the data in Table 4, after replacing the extreme pressure anti-wear agent in Comparative Example 3, not only was the anti-wear performance reduced, but the breakdown voltage also decreased and the copper corrosion level decreased. This proves that the replaced anti-wear agent did not overcome the contradiction between anti-wear and insulation, nor did it solve the contradiction between extreme pressure and corrosion.

[0121] In summary, the long-life new energy vehicle gearbox oil proposed in this invention has the characteristics of long life, good low-temperature performance, and excellent overall performance.

[0122] More specifically, although exemplary embodiments of the invention have been described herein, the invention is not limited to these embodiments, but includes any and all embodiments modified, omitted, such as combinations between various embodiments, adaptive changes, and / or substitutions, as would be apparent to those skilled in the art from the foregoing detailed description. The limitations in the claims are to be interpreted broadly as used in the language of the claims and are not limited to the examples described in the foregoing detailed description or during the implementation of this application, which should be considered non-exclusive. Any step listed in any method or process claim may be performed in any order and is not limited to the order set forth in the claims. Therefore, the scope of the invention should be determined solely by the appended claims and their legal equivalents, and not by the description and examples given above.

[0123] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of conflict, the definitions in this specification shall prevail. When a rate, pressure, temperature, time, or other value or parameter is expressed as a range, preferred range, or a range defined by a series of upper and lower preferred values, this shall be understood to specifically disclose all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether such range is disclosed individually. For example, the range 1-50 should be understood to include any number, combination of numbers, or subrange selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50, as well as all decimal values ​​between the integers mentioned above, such as 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. Regarding subranges, specifically consider "nested subranges" extending from any endpoint of the range. For example, nested sub-ranges of the exemplary range 1-50 may include 1-10, 1-20, 1-30 and 1-40 in one direction, or 50-40, 50-30, 50-20 and 50-10 in another direction.

Claims

1. A long-life gearbox oil for new energy vehicles, characterized in that, It comprises the following components by weight percentage: 1.5%-4% metal deactivator, 3%-5% antioxidant, 3%-5% extreme pressure anti-wear agent, 4%-7% detergent-dispersant, 0.3%-1% pour point depressant, 0.1%-0.3% defoamer, with the balance being base oil; The metal deactivator is molybdenum dialkyldithiocarbamate; The extreme pressure anti-wear agent is a composite of N,P-doped carbon quantum dot solution and nano-calcium carbonate or nano-zirconium dioxide in a mass ratio of 2:(1~2). The raw materials for the N,P-doped carbon quantum dot solution include sodium citrate and aminotrimethylenephosphonic acid, and its preparation process is as follows: Step 1: Sodium citrate and aminotrimethylenephosphonic acid are added to water at a mass ratio of (2~3):1 and stirred evenly. The mixture is then reacted at 190~210℃ for 4~6 h according to the hydrothermal synthesis method to finally obtain a pale yellow liquid. Step 2: Sonicate the above pale yellow liquid for 0.8~1.2h, and filter it using a 0.2~0.24 μm filter membrane to obtain the filtered liquid; Step 3: Mix the filtered liquid with diethylene glycol methyl ether at a mass ratio of 1:(2~3), sonicate for 0.8~1.2h, and finally dehydrate by distillation at 110~130℃ to obtain the N,P doped carbon quantum dot solution to be used. The base oil is a blend of polyalphaolefin PAO4, synthetic ester base oil and 150N in a mass ratio of 4:(1~2):(1~2).

2. The special oil for new energy vehicle gearboxes according to claim 1, characterized in that, The selection criteria for the synthetic ester base oil are: kinematic viscosity at 40℃ of 18-22 mm. 2 Between 0.5 m / s, the kinematic viscosity at 100℃ is 4-5.5 mm. 2 Between / s, the pour point is not higher than -51℃.

3. The special oil for new energy vehicle gearboxes according to any one of claims 1-2, characterized in that, The cleaning and dispersing agent is one of diene succinimide and polyisobutylene bissuccinimide; the pour point depressant is polymethyl methacrylate 602HB.

4. A method for preparing a special oil for the gearbox of new energy vehicles as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Prepare an N,P-doped carbon quantum dot solution, and then combine it with nano-calcium carbonate or nano-zirconia to prepare an extreme pressure anti-wear agent; Step 2: Blend the base oil; Step 3: After heating, add metal deactivator, antioxidant, detergent-dispersant, pour point depressant, and defoamer to the blended base oil obtained in Step 2 and stir until homogeneous; Step 4: Add the extreme pressure anti-wear agent prepared in Step 1 to the mixture obtained in Step 3, stir, and perform ultrasonic treatment to obtain the special oil for new energy vehicle gearboxes.

5. The preparation method of the special oil for new energy vehicle gearboxes according to claim 4, characterized in that, In step 3, after heating to 35~45℃, add metal deactivator, antioxidant, detergent dispersant, pour point depressant and defoamer, and maintain the above temperature while stirring for 0.8~1.2 h; in step 4, after adding extreme pressure anti-wear agent, stir at 50~70℃ for 1.5~2.5 h, and then use ultrasonic treatment for 0.8~1.2 h.

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