A lubricating oil, its method of manufacture and use

Abstract

The application provides a lubricating oil, comprising base oil and additives; the base oil comprises low viscosity poly-alpha olefin; the additives comprise extreme pressure anti-wear agent, friction modifier and polymethyl acrylate viscosity index improver; the mass of the extreme pressure anti-wear agent is 1% to 10% of the mass of the lubricating oil; the mass of the friction modifier is 0.01% to 1% of the mass of the lubricating oil; and the mass of the polymethyl acrylate viscosity index improver is 1% to 10% of the mass of the lubricating oil. Compared with the prior art, the lubricating oil provided by the application has higher oxidation resistance and shear resistance by the synergistic effect of the base oil and the additives, is a low viscosity fluid and a low traction coefficient fluid at the same time, can effectively enhance the tooth shaft protection capability, improve the cooling and heat dissipation performance and improve the electric drive transmission efficiency, can provide efficiency advantage and tooth shaft protection advantage for the vehicle transmission system, and has obvious improvement effect on cooling and heat dissipation.

Description

Technical Field

[0001] This invention belongs to the field of lubricating oil technology, and particularly relates to a lubricating oil, its preparation method and its uses. Background Technology

[0002] Early electric vehicles typically used general-purpose motors—composed of bearings and parts from the traditional gasoline-powered vehicle transmission system. However, in newer electric vehicles, to achieve a compact transmission structure with fewer transmission components, and to minimize power loss, reduce wear, and cool friction pairs, the motor and mechanical transmission components are increasingly adopting an integrated drive system. The drive and transmission systems of electric vehicles are evolving from general-purpose to specialized systems. This presents new challenges to the cooling, insulation, and corrosion resistance of lubricants. Products that can adapt to more complex working environments and have greater compatibility will be the future development trend of automotive lubricants.

[0003] Currently used lubricant technologies are all generic formulations from additive companies (such as Lubrizol, Infineum, and Afton) or lubricant companies (such as Exxon Mobil, Shell, Castrol, and FUCHS). These generic formulations only address material compatibility and copper corrosion, lacking specific formulations for traditional electric drive lubricants designed to improve gear shaft protection, cooling, and efficiency. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a lubricating oil with a low coefficient of traction friction and high cooling and heat dissipation performance, its preparation method and its use.

[0005] This invention provides a lubricating oil comprising a base oil and additives;

[0006] The base oil comprises low-viscosity polyalphaolefin;

[0007] The additives include extreme pressure anti-wear agents, friction modifiers, and polymethyl methacrylate viscosity index improvers;

[0008] The extreme pressure anti-wear agent has a mass of 1% to 10% of the lubricating oil mass;

[0009] The friction modifier accounts for 0.01% to 1% of the mass of the lubricating oil.

[0010] The mass of the polymethyl methacrylate viscosity index improver is 1% to 10% of the mass of the lubricating oil.

[0011] Preferably, the base oil comprises PAO2 and PAO4;

[0012] And / or, the mass of the PAO2 is 75% to 90% of the mass of the lubricating oil;

[0013] And / or; the mass of the PAO4 is 1% to 10% of the mass of the lubricating oil.

[0014] Preferably, the mass of the PAO2 is 83% of the mass of the lubricating oil;

[0015] And / or, the mass of the PAO4 is 6% to 7% of the mass of the lubricating oil.

[0016] Preferably, the PAO2 is selected from one or more of DURASYN 142, SPECTRASYN 2, and DURASYN 162;

[0017] And / or, the PAO4 is selected from one or more of DURASYN 164, DURASYN 136 and DURASYN 133.

[0018] Preferably, the additive includes elements S, P, B, Ca, and Si;

[0019] The additives contain 500–2000 ppm of element S, 100–300 ppm of element P, 10–100 ppm of element B, 100–200 ppm of element Ca, and less than 10 ppm of element Si.

[0020] Preferably, and / or, the extreme pressure anti-wear agent accounts for 4% to 5% of the mass of the lubricating oil;

[0021] And / or, the friction modifier is 0.04% to 0.05% of the mass of the lubricating oil;

[0022] And / or, the mass of the polymethacrylate viscosity index improver is 5% to 6% of the mass of the lubricating oil.

[0023] Preferably, the polymethacrylate viscosity index improver includes Viscoplex 3-195 and HiTEC5769;

[0024] The mass ratio of Viscoplex 3-195 to HiTEC 5769 is 1:(0.8 to 1.1).

[0025] Preferably, the extreme pressure anti-wear agent includes 35790 35750 and One or more of 35701;

[0026] And / or, the friction modifier includes 35791 and / or 5760.

[0027] Preferably, the base oil comprises PAO2 and PAO4;

[0028] The PAO2 accounts for 83% of the mass of the lubricating oil; the PAO2 is selected from one or more of DURASYN 142, SPECTRASYN 2, and DURASYN 162.

[0029] The PAO4 comprises 6.63% of the mass of the lubricating oil; the PAO4 is selected from one or more of DURASYN 164, DURASYN 136, and DURASYN 133.

[0030] The extreme pressure anti-wear agent comprises 4.5% of the mass of the lubricating oil; the extreme pressure anti-wear agent includes... 35790 35750 and One or more of 35701;

[0031] The friction modifier comprises 0.04% of the mass of the lubricating oil; the friction modifier includes... 35791 and / or 5760;

[0032] The polymethacrylate viscosity index improvers include Viscoplex 3-195 and HiTEC 5769;

[0033] The Viscoplex 3-195 is 3% of the mass of the lubricating oil.

[0034] The mass of HiTEC 5769 is 2.83% of the mass of the lubricating oil.

[0035] Preferably, the lubricating oil has one or more of the properties of (1) to (14):

[0036] (1) Flash point ≥ 180℃;

[0037] (2) Pour point ≤ -40℃;

[0038] (3) Kinematic viscosity at 100℃: 3~5mm 2 / s;

[0039] (4) Kinematic viscosity at 40℃: 12.0~15.0 mm 2 / s;

[0040] (5) -40℃ Brinell viscosity: ≤1500mPa·s;

[0041] (6) GB / T12579-90 Foam Properties: Unit: ml / ml

[0042] 24℃, 25 / 0;

[0043] 93.5℃, 50 / 0;

[0044] After 24℃, 25 / 0;

[0045] (7) Thermal conductivity: ≥0.13W / m·K at 80℃;

[0046] (8) Specific heat capacity: ≥2.0 J / g·K at 80℃;

[0047] (9) After 20h of KRL shear stability test at 60℃, KV100≤4%, KV40≤0.1%;

[0048] (10) Evaporation loss at 150℃ for 1 hour ≤5%;

[0049] (11) Evaporation loss at 200℃ for 1 hour ≤10%;

[0050] (12) The kinematic viscosity change rate at 170℃ and 192h is 0 to -1% at 100℃;

[0051] (13) The kinematic viscosity change rate at 170℃ and 40℃ is ≤2% after 192 hours.

[0052] (14) The copper corrosion grade coefficient at 150℃ for 3 hours is selected from 1A or 1B.

[0053] The present invention also provides a method for preparing the above-mentioned lubricating oil, comprising the following steps:

[0054] The base oils are mixed, and under stirring and heating conditions, extreme pressure anti-wear agents, friction modifiers and polymethyl methacrylate viscosity index modifiers are added to the mixed base oils to obtain lubricating oil.

[0055] The present invention also provides an electric drive transmission system comprising the aforementioned lubricating oil.

[0056] The present invention also provides a vehicle including the above-described electric drive transmission system.

[0057] This invention provides a lubricating oil comprising a base oil and additives. The base oil comprises a low-viscosity polyalphaolefin. The additives comprise an extreme pressure anti-wear agent, a friction modifier, and a polymethyl methacrylate viscosity index improver. The extreme pressure anti-wear agent comprises 1% to 10% of the lubricating oil's mass; the friction modifier comprises 0.01% to 1% of the lubricating oil's mass; and the polymethyl methacrylate viscosity index improver comprises 1% to 10% of the lubricating oil's mass. Compared with existing technologies, the lubricating oil provided by this invention, through the synergistic effect of the base oil and additives, achieves high oxidation resistance and shear resistance while being a low-viscosity and low-traction coefficient fluid. This effectively enhances gear shaft protection, improves cooling performance, and increases electric drive transmission efficiency, providing efficiency and gear shaft protection advantages for vehicle transmission systems, and significantly improves cooling performance. Attached Figure Description

[0058] Figure 1 This is a molecular structure diagram of polyalphaolefin base oil;

[0059] Figure 2 This is a schematic diagram of a micro-traction force tester for testing the performance of lubricating oil.

[0060] Figure 3 The graph shows the test results of the traction coefficient COF of the lubricating oil obtained in Example 1 and Comparative Examples 1-2;

[0061] Figure 4 The graph shows the test results of the traction coefficient COF of the lubricating oil obtained in Example 1 and Comparative Examples 1-2. Detailed Implementation

[0062] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0063] Because electric vehicles have more complex systems, integrating a large number of electronic components, the demands on lubricants in their motor systems are much more stringent. Therefore, electric vehicle lubricants face numerous challenges in terms of chemical and physical performance. First, transmission fluid must maintain excellent oxidation stability under the high temperatures generated by the high-speed operation of the motor, while simultaneously providing efficient heat dissipation. Second, it needs to provide excellent cooling capacity. Lower viscosity and a thinner oil film result in better heat dissipation, which is beneficial to the motor, but a relatively thin oil film is detrimental to the protection of gears and bearings within the reducer. This poses a challenge to the viscosity index of the lubricant. Third, good electrochemical performance is crucial. To improve the high and low temperature performance of the lubricant and its protection of gears, some active elements added to the lubricant (such as sulfur and phosphorus) can corrode copper wires, thus placing higher demands on the compatibility of the lubricant with electrical components. Therefore, lubricant formulation research must simultaneously consider high and low temperature performance, gear protection, compatibility with electrical components, conductivity control, and other aspects to increase the durability of the transmission fluid and extend oil change intervals.

[0064] To address the aforementioned problems, this invention provides a lubricating oil comprising a base oil and additives; the base oil comprises a low-viscosity polyalphaolefin; the additives comprise an extreme pressure anti-wear agent, a friction modifier, and a polymethyl methacrylate viscosity index improver; the extreme pressure anti-wear agent comprises 1% to 10% of the mass of the lubricating oil; the friction modifier comprises 0.01% to 1% of the mass of the lubricating oil; and the polymethyl methacrylate viscosity index improver comprises 1% to 10% of the mass of the lubricating oil.

[0065] In this invention, the base oil comprises a polyalphaolefin. The molecular structure of the polyalphaolefin base oil is as follows: Figure 1 As shown. By Figure 1 It is known that the molecular structure of polyalphaolefins is characterized by regular molecular chains, long carbon chain main chains, and few branches. According to molecular dynamics, branches intensify the atomic motion in the polymer chain, thereby reducing thermal conductivity. The molecular structure with long main chains and few branches gives polyalphaolefins high heat transfer performance, can maintain stable lubrication performance at high temperatures, can effectively separate contact surfaces, reduce friction, and reduce wear.

[0066] In one specific embodiment of the present invention, the base oil includes PAO2 and PAO4; the PAO2 can be any PAO2 known to those skilled in the art, and there are no special limitations. In the present invention, it is preferably one or more of DURASYN 142, SPECTRASYN 2, and DURASYN 162; the PAO4 can be any PAO4 known to those skilled in the art, and there are no special limitations. In the present invention, it is preferably one or more of DURASYN 164, DURASYN 136, and DURASYN 133.

[0067] In one specific embodiment of the present invention, the mass of PAO2 is preferably 75% to 90% of the mass of the lubricating oil; optionally, the mass of PAO2 is 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90% of the mass of the lubricating oil, or a range between any two of the above values.

[0068] In one specific embodiment of the present invention, the mass of PAO4 is preferably 1% to 10% of the mass of the lubricating oil; optionally, the mass of PAO4 is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% of the mass of the lubricating oil or a range between any two of the above values.

[0069] In one specific embodiment of the present invention, the mass of PAO4 is preferably 5% to 7% of the mass of the lubricating oil, more preferably 6% to 7%, even more preferably 6.5% to 6.7%, and most preferably 6.63%.

[0070] In a specific embodiment of the present invention, the additive includes elements S, P, B, Ca, and Si; wherein the content of element S in the additive is 500-2000 ppm, the content of element P is 100-300 ppm, the content of element B is 10-100 ppm, the content of element Ca is 100-200 ppm, and the content of element Si is less than 10 ppm.

[0071] The additives include extreme pressure anti-wear agents, friction modifiers, and polymethyl methacrylate viscosity index improvers.

[0072] In this invention, optionally, the mass of the extreme pressure anti-wear agent is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% of the mass of the lubricating oil, or a range between any two of the above values.

[0073] In one specific embodiment of the present invention, the mass of the extreme pressure anti-wear agent is preferably 3% to 8% of the mass of the lubricating oil, more preferably 3% to 6%, even more preferably 4% to 5%, and most preferably 4.5%.

[0074] Specifically, the extreme pressure anti-wear agent described in this invention is preferably a Hitech3 series additive, and more preferably... 35790 35750 and One or more of 35701.

[0075] In this invention, optionally, the mass of the friction modifier is 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1% of the mass of the lubricating oil, or a range between any two of the above values.

[0076] In a specific embodiment of the present invention, the mass of the friction modifier is preferably 0.01% to 0.5% of the mass of the lubricating oil, more preferably 0.02% to 0.1%, even more preferably 0.02% to 0.06%, even more preferably 0.04% to 0.05%, and most preferably 0.04%.

[0077] Specifically, in this invention, the friction modifier is preferably a Hitech3 series additive and / or a Hitech5 series additive, more preferably... 35791 and / or 5760.

[0078] The additives provided by this invention include polymethacrylate viscosity index improvers. Polymethacrylate viscosity index improvers have the advantages of low drag coefficient and high viscosity index, and are more robust in improving the efficiency of transmission systems than other viscosity index improver technologies (such as polyisobutylene).

[0079] In this invention, optionally, the mass of the polymethacrylate viscosity index improver is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% of the mass of the lubricating oil, or a range between any two of the above values.

[0080] In one specific embodiment of the present invention, the mass of the polymethyl methacrylate viscosity index improver is preferably 3% to 8% of the mass of the lubricating oil, more preferably 4% to 6%, even more preferably 5% to 6%, and most preferably 5.5% to 6%.

[0081] In one specific embodiment of the present invention, the polymethacrylate viscosity index improver preferably includes Viscoplex 3-195 and HiTEC 5769; the mass ratio of Viscoplex 3-195 to HiTEC 5769 is preferably 1:(0.8 to 1.1); optionally, the mass ratio of Viscoplex 3-195 to HiTEC 5769 is 1:0.8, 1:0.9, 1:1, 1:1.1 or any two of the above ratios.

[0082] By adding the above-mentioned additives, the present invention enables the lubricating oil to form a soft film on the metal surface, which has a low coefficient of friction, reduces friction loss, improves transmission efficiency, and also improves the oxidation resistance and shear resistance of the lubricating oil.

[0083] In a specific embodiment of the present invention, the base oil comprises PAO2 and PAO4; the mass of PAO2 is 83% of the mass of the lubricating oil; the PAO2 is selected from one or more of DURASYN 142, SPECTRASYN 2, and DURASYN 162; the mass of PAO4 is 6.63% of the mass of the lubricating oil; the PAO4 is selected from one or more of DURASYN 164, DURASYN 136, and DURASYN 133; the mass of the extreme pressure anti-wear agent is 4.5% of the mass of the lubricating oil; the extreme pressure anti-wear agent comprises... 35790 35750 and One or more of 35701; the friction modifier is 0.04% of the mass of the lubricating oil; the friction modifier includes... 35791 and / or 5760; the polymethacrylate viscosity index improver includes Viscoplex 3-195 and HiTEC 5769; the mass of Viscoplex 3-195 is 3% of the mass of the lubricating oil; the mass of HiTEC 5769 is 2.83% of the mass of the lubricating oil.

[0084] In one specific embodiment of the present invention, the lubricating oil comprises, by mass percentage, 83% PAO2, 6.63% PAO4, and 4.5% PAO2. 35790, 0.04% 35791, 3% Viscoplex 3-195 and 2.83% HiTEC 5769.

[0085] In another specific embodiment provided by the present invention, the additive further includes one or more of extreme pressure additives, anti-wear additives, friction-reducing additives, antioxidants, corrosion inhibitors, metal passivators, dispersants, detergents and defoamers.

[0086] Specifically, the extreme pressure additive is an additive that can form a high-melting-point chemical reaction film with the metal surface under high temperature and high pressure boundary lubrication conditions, and is an additive that can play a lubricating role under the condition that the oiliness agent fails. Extreme pressure additives can be divided into several categories, including organosulfur compounds, organophosphorus compounds, chlorides and organometallic salts, preferably including, but not limited to, one or more of phosphate esters, thiophosphate esters and phosphate ester amine salts. The mass of the extreme pressure additive can be 0.1% to 5% of the mass of the base oil, and can be selected according to the type of additive.

[0087] Specifically, anti-wear additives are high-tech lubricant additives. Commonly used anti-wear agents in lubricating oils include sulfur-based anti-wear agents, phosphorus-based anti-wear agents, sulfur-phosphorus anti-wear agents, halogen-based anti-wear agents, organometallic anti-wear agents, and boron-based anti-wear agents. They can reduce engine wear and increase engine power, so they are also known as engine maintenance agents or powerful repair agents. They can extend the service life of engine oil, save fuel, and improve power. The mass of the anti-wear additive can be 0.1% to 5% of the mass of the base oil, and can be selected according to the type added.

[0088] Specifically, friction-reducing additives are mainly used to reduce friction and wear between mechanical parts, thereby extending the service life of mechanical equipment, reducing maintenance frequency and downtime, lowering maintenance costs, and improving production efficiency. In this invention, the friction-reducing additive can be one or more of nano-copper (Cu), zinc oxide (ZnO), and aluminum oxide (Al2O3). The mass of the friction-reducing additive can be 0.1% to 5% of the mass of the base oil, and can be selected according to the type added.

[0089] Specifically, the antioxidant can be selected from one or more of alkylated diphenylamine, N-phenyl-α-naphthylamine, shielded phenols, and phenolic esters. For example, it can be selected from one or more of dibutyldiphenylamine, dioctyldiphenylamine, butyl / octyldiphenylamine, bis(dodecyl)diphenylamine, bis(pentyl)diphenylamine, N-phenyl-α-naphthylamine, 2,6-di-tert-butyl-p-cresol, and 2,6-di-tert-butyl-4-hydroxyphenylpropionate. Common commercial brands include T534, T531, and T501. The antioxidant is preferably 0.5% to 3% of the base oil mass, and can be selected according to the type added.

[0090] Specifically, a corrosion inhibitor is an additive that can effectively slow down the corrosion rate of metals. It can be one or more of dialkyl dithiophosphates, sulfonates, esters, and organophosphates, such as zinc dialkyl dithiophosphate (ZnDDP), petroleum sulfonates, synthetic sulfonates, sorbitol monoester of oleic acid, pentaerythritol monoester of oleic acid, dodecenyl succinate half ester, lanolin, mono- or di-tridecyl phosphate dodecyloxypropyl isopropanolamine salt, and alkyl phosphate imidazoline. The corrosion inhibitor is preferably 0.1% to 5% of the base oil mass, and can be selected according to the type added.

[0091] Specifically, the main function of metal passivators is to protect the metal parts on the surface of machines, preventing rust and corrosion when in contact with lubricating oil. Metal passivators form a protective film on the metal surface, preventing the erosion of oxygen and moisture, reducing friction and wear, and protecting the machine's operating efficiency and lifespan. Metal passivators are typically compounds containing sulfur, phosphorus, nitrogen, or other non-metallic elements, and their main varieties include benzotriazole derivatives and thiadiazole derivatives. Common metal passivators used in lubricating oils in China include T551 and T561. The preferred mass of the metal passivator is 0.1% to 3% of the base oil mass, and the choice can be made depending on the type added.

[0092] Specifically, the dispersant is an ashless dispersant, which can be polyisobutylene succinimide and / or boronized polyisobutylene succinimide. For example, it can be one or more of monopolyisobutylene succinimide, dipolyisobutylene succinimide, high molecular weight polyisobutylene succinimide, and boronized dipolyisobutylene succinimide. Common commercial brands include T151, T154, T161, T154B, etc.

[0093] Specifically, detergents are chemicals that clean and keep engine parts clean. Their functions can be categorized into four aspects: acid neutralization, solubilization, dispersion, and washing. Commonly used detergents fall into five main categories: sulfonates, alkylphenol sulfides, alkyl salicylates, thiophosphates, and naphthenates.

[0094] Specifically, the defoamer can be one or more of silicone oil defoamers, organosilicon defoamers, and surfactant defoamers, and can be selected according to factors such as the type of base oil of the lubricating oil, operating temperature, and operating environment.

[0095] According to the present invention, the lubricating oil has one or more of the properties of (1) to (14):

[0096] (1) Flash point ≥ 180℃;

[0097] (2) Pour point ≤ -40℃;

[0098] (3) Kinematic viscosity at 100℃: 3~5mm2 / s;

[0099] (4) Kinematic viscosity at 40℃: 12.0~15.0 mm 2 / s;

[0100] (5) -40℃ Brinell viscosity: ≤1500mPa·s;

[0101] (6) GB / T12579-90 Foam Properties: Unit: ml / ml

[0102] 24℃, 25 / 0;

[0103] 93.5℃, 50 / 0;

[0104] After 24℃, 25 / 0;

[0105] (7) Thermal conductivity: ≥0.13W / m·K at 80℃;

[0106] (8) Specific heat capacity: ≥2.0 J / g·K at 80℃;

[0107] (9) After 20h of KRL shear stability test at 60℃, KV100≤4%, KV40≤0.1%;

[0108] (10) Evaporation loss at 150℃ for 1 hour ≤5%;

[0109] (11) Evaporation loss at 200℃ for 1 hour ≤10%;

[0110] (12) The kinematic viscosity change rate at 170℃ and 192h is 0 to -1% at 100℃;

[0111] (13) The kinematic viscosity change rate at 170℃ and 40℃ is ≤2% after 192 hours.

[0112] (14) The copper corrosion grade coefficient at 150℃ for 3 hours is selected from 1A or 1B.

[0113] The lubricating effect of lubricating oil on mechanical parts can be mainly classified into three types: boundary lubrication, mixed lubrication, and fluid lubrication. In boundary lubrication, the speed is very low, and the lubricating oil film thickness is insufficient to completely separate the two surfaces. Surface roughness plays a dominant role, and the properties of additives have a significant impact on friction. Compared to boundary lubrication, in mixed lubrication, the thickness of the lubricating oil film gradually increases, but there is still direct contact between the surfaces. The coefficient of friction begins to decrease with increasing speed or decreasing load. In fluid lubrication, once the lubricating oil film is sufficient, it can completely separate the two surfaces, avoiding direct contact. The fluidity of the lubricating oil is needed to improve lubrication, thus reducing the coefficient of friction with increasing speed. The lubricating oil formulation provided by this invention may be attributed to its ability to provide lower friction and traction through boundary lubrication, mixed lubrication, and / or elastohydrodynamic lubrication, reducing friction loss, improving transmission efficiency, and consequently improving gear transmission protection, motor cooling, and drive unit efficiency.

[0114] In summary, the lubricating oil provided by this invention, through the synergistic effect of base oil and additives, makes the lubricating oil a low-viscosity fluid and a low-traction coefficient fluid while having high oxidation resistance and shear resistance. It can effectively enhance the gear shaft protection capability, improve cooling and heat dissipation performance, and enhance the efficiency of electric drive transmission. It can provide efficiency advantages and gear shaft protection advantages for vehicle transmission systems, and has a significant improvement effect on cooling and heat dissipation.

[0115] The present invention also provides a method for preparing the above-mentioned lubricating oil, comprising: mixing base oil, and adding a first additive, a second additive and a third additive to the mixed base oil under stirring and heating conditions to obtain lubricating oil.

[0116] The stirring speed is preferably 30 to 150 rpm; the heating temperature is preferably 50°C to 70°C.

[0117] The present invention also provides an electric drive transmission system comprising the aforementioned lubricating oil.

[0118] The present invention also provides an electric vehicle, including the above-described electric drive transmission system.

[0119] To further illustrate the present invention, the following describes in detail, with reference to embodiments, a lubricating oil provided by the present invention, its preparation method and its uses.

[0120] All reagents used in the following examples are commercially available.

[0121] Examples and Comparative Examples

[0122] Preparation process: Add the base oil from the formula (the formula is shown in Table 1, where % are all mass percentages), start stirring (80 rpm), start heating to 60℃, add the first additive, the second additive and the third additive, continue stirring and start circulation; after QC inspection is qualified, turn off the stirring / heating and circulation processes.

[0123] Table 1 Lubricating Oils

[0124]

[0125] The performance of the lubricating oils obtained in the examples and comparative examples was tested, and the results are shown in Table 2.

[0126] The performance of the lubricating oils obtained in Example 1 and Comparative Examples 1 and 2 was tested using a Mini-Traction Machine. A schematic diagram of the testing device for testing the lubricating oil performance is shown below. Figure 2 As shown, 1 is an RGB color camera, 2 is a microscope and spacer coating disk, 3 is a steel ball, 4 is a heater, 5 is lubricating oil, and 6 is a steel disk. Test conditions: speed -5m / s to 5m / s, load 3000N (contact stress 4.2GPa max), temperature: ambient temperature to 180℃. The detection results of the traction coefficient (COF) of the lubricating oil obtained in Example 1 and Comparative Examples 1-2 are shown in the figure below. Figure 3 and Figure 4 As shown. Figure 3 and Figure 4 The horizontal axis represents temperature (°C), sliding-roll ratio (%), load (MPa), and linear velocity (mm / s) from bottom to top; the vertical axis represents the coefficient of friction. Figure 3 and Figure 4 The fluid codes are as follows: 1481 is Comparative Example 1, 1482 is Example 1, and 1483 is Comparative Example 2.

[0127] Table 2 Performance test results of lubricating oil

[0128]

[0129]

[0130] As shown in Table 2, the lubricating oil prepared in Example 1 has a high viscosity index, good viscosity-temperature performance, and a low Brookfield viscosity at low temperatures, which is conducive to the formation of an effective oil film, and has high shear stability and low evaporation loss. Figure 3 and Figure 4The results of friction coefficient tests of the lubricating oil at 40℃ and 60℃ are shown. It can be seen that the friction coefficient of the lubricating oil provided in Example 1 is lower than that of Comparative Example 1 and Comparative Example 2 under conditions of higher slip-roll ratio, load and linear velocity. This indicates that the lubricating oil provided by the present invention not only has high stability but also has a low traction coefficient, which can reduce friction loss, thereby effectively enhancing the gear shaft protection capability, improving cooling and heat dissipation performance and increasing the efficiency of electric drive transmission.

[0131] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A lubricating oil, characterized in that, The lubricating oil includes base oil and additives; The base oil comprises low-viscosity polyalphaolefin; The additives include extreme pressure anti-wear agents, friction modifiers, and polymethyl methacrylate viscosity index improvers; The extreme pressure anti-wear agent has a mass of 1% to 10% of the lubricating oil mass; The friction modifier accounts for 0.01% to 1% of the mass of the lubricating oil. The mass of the polymethyl methacrylate viscosity index improver is 1% to 10% of the mass of the lubricating oil.

2. The lubricating oil according to claim 1, characterized in that, The base oils include PAO2 and PAO4; And / or, the mass of the PAO2 is 75% to 90% of the mass of the lubricating oil; And / or; the mass of the PAO4 is 1% to 10% of the mass of the lubricating oil.

3. The lubricating oil according to claim 2, characterized in that, The mass of PAO2 is 83% of the mass of the lubricating oil; And / or, the mass of the PAO4 is 6% to 7% of the mass of the lubricating oil.

4. The lubricating oil according to claim 2 or 3, characterized in that, The PAO2 is selected from one or more of DURASYN 142, SPECTRASYN 2 and DURASYN 162; And / or, the PAO4 is selected from one or more of DURASYN 164, DURASYN 136 and DURASYN 133.

5. The lubricating oil according to any one of claims 1 to 4, characterized in that, The additives include elements S, P, B, Ca, and Si; The additive contains 500-2000 ppm of element S, 100-300 ppm of element P, 10-100 ppm of element B, 100-200 ppm of element Ca, and less than 10 ppm of element Si. And / or, the mass of the extreme pressure anti-wear agent is 4% to 5% of the mass of the lubricating oil; And / or, the friction modifier is 0.04% to 0.05% of the mass of the lubricating oil; And / or, the mass of the polymethacrylate viscosity index improver is 5% to 6% of the mass of the lubricating oil.

6. The lubricating oil according to any one of claims 1 to 5, characterized in that, The polymethyl methacrylate viscosity index improvers include Viscoplex 3-195 and HiTEC 5769; The mass ratio of Viscoplex3-195 to HiTEC 5769 is 1:(0.8~1.1); And / or, the extreme pressure anti-wear agent includes 35790 35750 and One or more of 35701; And / or, the friction modifier includes 35791 and / or 5760.

7. The lubricating oil according to any one of claims 1 to 6, characterized in that, The base oils include PAO2 and PAO4; The PAO2 accounts for 83% of the mass of the lubricating oil; the PAO2 is selected from one or more of DURASYN 142, SPECTRASYN 2, and DURASYN 162. The PAO4 comprises 6.63% of the mass of the lubricating oil; the PAO4 is selected from one or more of DURASYN 164, DURASYN 136, and DURASYN 133. The extreme pressure anti-wear agent comprises 4.5% of the mass of the lubricating oil; the extreme pressure anti-wear agent includes... 35790 35750 and One or more of 35701; The friction modifier comprises 0.04% of the mass of the lubricating oil; the friction modifier includes... 35791 and / or 5760; The polymethyl methacrylate viscosity index improvers include Viscoplex 3-195 and HiTEC 5769; The mass of Viscoplex3-195 is 3% of the mass of the lubricating oil; The mass of HiTEC 5769 is 2.83% of the mass of the lubricating oil.

8. The lubricating oil according to any one of claims 1 to 7, characterized in that, The lubricating oil has one or more of the properties of (1) to (14): (1) Flash point ≥ 180℃; (2) Pour point ≤ -40℃; (3) Kinematic viscosity at 100℃: 3~5mm 2 / s; (4) Kinematic viscosity at 40℃: 12.0~15.0 mm 2 / s; (5) -40℃ Brinell viscosity: ≤1500mPa·s; (6) GB / T12579-90 Foam Properties: Unit: ml / ml 24℃，25 / 0； 93.5℃，50 / 0； After 24℃, 25 / 0; (7) Thermal conductivity: ≥0.13W / m·K at 80℃; (8) Specific heat capacity: ≥2.0 J / g·K at 80℃; (9) After 20h of KRL shear stability test at 60℃, KV100≤4%, KV40≤0.1%; (10) Evaporation loss at 150℃ for 1 hour ≤5%; (11) Evaporation loss at 200℃ for 1 hour ≤10%; (12) The kinematic viscosity change rate at 170℃ and 192h at 100℃ is 0 to -1%. (13) The kinematic viscosity change rate at 170℃ and 192h (40℃) is ≤2%. (14) The copper corrosion grade coefficient at 150℃ for 3 hours is selected from 1A or 1B.

9. A method for preparing the lubricating oil according to any one of claims 1 to 8, characterized in that, Includes the following steps: The base oils are mixed, and under stirring and heating conditions, extreme pressure anti-wear agents, friction modifiers and polymethyl methacrylate viscosity index modifiers are added to the mixed base oils to obtain lubricating oil.

10. An electric drive transmission system, characterized in that, This includes the lubricating oil according to any one of claims 1 to 8 or the lubricating oil prepared by the preparation method according to claim 9.

11. A vehicle, characterized in that, Includes the electric drive system as described in claim 10.

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