A transmission lubricating oil composition and its preparation and application

Abstract

The invention discloses a transmission lubricant composition and its preparation and application. The transmission lubricant composition comprises, by mass, 0.1 to 0.5 parts of a phosphorus-containing agent; 0.4 to 1.5 parts of a thiocarboxylate additive; 0.3 to 0.6 parts of an antioxidant; 1.0 to 2.0 parts of an antioxidant and an anti-corrosion additive; 1.25 to 1.95 parts of a detergent; 1.5 to 2.5 parts of an ashless dispersant; 0.005 to 0.03 parts of an anti-foaming agent; and the balance of base oil. The phosphorus-containing agent is triphenyl thiophosphate; and the thiocarboxylate additive is a dialkyl thiodicarboxylate or a dialkyl dithiodicarboxylate. The present invention compounds triphenyl thiophosphate with a thiocarboxylate additive to produce a lubricating oil composition exhibiting excellent high extreme pressure properties and outstanding copper corrosion protection performance. The lubricating oil composition achieves an FZG (A10 / 16.6R / 90) rating greater than 12, while achieving level 1 in a long-cycle copper sheet corrosion test (150°C, 168 hours). The wear loss in an FE8 bearing test is less than 1 mg, making the lubricating oil composition suitable for lubrication of integrated electric drive axles of commercial vehicles.

Description

Technical Field

[0001] This invention relates to a transmission lubricating oil composition and its preparation and application. Background Art

[0002] With the adjustment of the energy structure, new energy vehicles will become the mainstream direction of the automotive industry. In the commercial vehicle sector, electric drive axles, as the core powertrain of pure electric logistics vehicles and buses, are developing rapidly. The latest drive motors, gear reducers, and controllers are highly integrated into one unit, namely the electric drive axle. The electric drive axle is the power system and transmission system of new energy vehicles, providing power to the entire vehicle, bearing loads, reducing speed, increasing torque, and ensuring differential speed between the left and right wheels. Integrated electric drive axles have advantages such as compact structure, high transmission efficiency, and low cost. Unlike passenger cars, commercial vehicles face heavy-load and long-cycle operating conditions. Therefore, the lubricating oil used in the integrated electric drive axle gearbox needs not only good electrochemical performance but also high load-bearing capacity to provide good wear protection for bearings and gears. Considering the copper components inside the drive axle and its long-term use, the oil also needs to have excellent copper corrosion inhibition, oxidation stability, and deposit control capabilities to effectively protect the copper components in the motor. Summary of the Invention

[0003] To improve the electrochemical properties, load-carrying capacity, bearing protection performance, oxidation stability, and deposit control capabilities of lubricating oils, making them suitable for lubrication of integrated electric drive axle gearboxes in commercial vehicles, this invention provides a transmission lubricating oil composition. This composition effectively lubricates and protects key components within the electric drive axle, such as the motor, reducer, drive half-shaft, rigid axle housing, and wheel hub bearings, effectively extending the oil change interval.

[0004] As a first aspect of the present invention, there is a transmission lubricating oil composition comprising, by weight parts:

[0005] Phosphorus-containing agent: 0.1–0.5 parts; Thiocarboxylic acid ester additive: 0.4–1.5 parts; Antioxidant: 0.3–0.6 parts; Antioxidant and anticorrosive additive: 1.0–2.0 parts; Detergent: 1.25–1.95 parts; Ash-free dispersant: 1.5–2.5 parts; Antifoaming agent: 0.005–0.03 parts; Base oil: balance;

[0006] The phosphorus-containing agent is triphenyl thiophosphate (TPPT);

[0007] The thiocarboxylic acid ester additive is a dialkyl thiocarboxylic acid ester or a dialkyl dithiocarboxylic acid ester.

[0008] In one or more optional embodiments, the thiocarboxylic acid ester additive has the following general structural formula:

[0009]

[0010] Wherein, R1 is a straight-chain butyl or a straight-chain octyl, R2 is at least one of 1,3-cyclohexyl, 1,4-cyclohexyl and a hydrocarbon group having 3 to 7 carbon atoms, and n is 1 or 2.

[0011] In one or more optional embodiments, the thiocarboxylic acid ester additive is at least one of the following: di-n-butyl monothiodide (1,3-cyclohexanecarboxylic acid), di-n-butyl monothiodide (1,3-cyclohexanecarboxylic acid), di-n-octyl monothiodide (1,3-cyclohexanecarboxylic acid), di-n-butyl monothiodide (1,4-cyclohexanecarboxylic acid), di-n-butyl monothiodide (1,4-cyclohexanecarboxylic acid), di-n-octyl monothiodide (1,4-cyclohexanecarboxylic acid), and di-n-octyl monothiodide (1,4-cyclohexanecarboxylic acid).

[0012] In one or more optional embodiments, the mass ratio of the triphenyl thiophosphate to the thiocarboxylic acid ester additive is (0.2-0.4):1, preferably 0.25:1.

[0013] In one or more optional embodiments, the antioxidant is a mixture of octyl-N-phenyl-α-naphthylamine, monothiooctyl-N-phenyl-α-naphthylamine, and dithiooctyl-N-phenyl-α-naphthylamine.

[0014] In one or more optional embodiments, the mass ratio of octyl-N-phenyl-α-naphthylamine, monothiooctyl-N-phenyl-α-naphthylamine, and dithiooctyl-N-phenyl-α-naphthylamine is 1:(0.2-0.5):(0.2-0.5).

[0015] In one or more optional embodiments, the antioxidant and anti-corrosion additives T202 and T205 are a mixture.

[0016] In one or more optional embodiments, the mass ratio of T202 to T205 is (1-3):1, preferably 1:1.

[0017] In one or more optional embodiments, the ashless dispersant is polyisobutylene succinimide with a molecular weight greater than 3000.

[0018] In one or more alternative embodiments, the base oil is a mixture of PMA-type viscosity index improver, polyalphaolefin, and API Group III mineral base oil.

[0019] In one or more optional embodiments, the polyalphaolefin is PAO100 base oil or mPAO65 base oil.

[0020] In one or more optional embodiments, the kinematic viscosity of the API Group III mineral base oil is 3 to 10 cSt.

[0021] In one or more optional embodiments, the detergent is at least one of calcium alkylbenzene sulfonate with a base number (i.e., TBN) greater than 300 and magnesium sulfonate with a base number greater than 400.

[0022] In one or more optional embodiments, the antifoaming agent is a polyacrylate-based antifoaming agent with a molecular weight of 60,000.

[0023] In one or more optional embodiments, the composition comprises, by weight parts:

[0024] Phosphorus-containing agent: 0.2–0.5 parts;

[0025] Thiocarboxylic acid ester additive: 0.8–1.5 parts;

[0026] Antioxidant: 0.4–0.6 parts;

[0027] Antioxidant and anti-corrosion additives: 1.0–1.6 parts;

[0028] Cleaning agent: 1.45–1.95 parts;

[0029] Ashless dispersant: 1.5–2.0 parts;

[0030] Antifoaming agent: 0.01–0.03 parts;

[0031] Base oil: Balance.

[0032] As a second aspect of the present invention, a method for preparing the above-described transmission lubricating oil composition is provided, the method comprising:

[0033] Add the phosphorus-containing agent, thiocarboxylic acid ester additive, antioxidant, antioxidant and anti-corrosion additive, detergent, ashless dispersant, antifoaming agent and base oil into a container according to the ratio, and mix at 50-60℃ for 2 hours until all components are uniformly dissolved.

[0034] As a third aspect of the invention, the application of the above-described transmission lubricant composition in an integrated electric drive axle for commercial vehicles is discussed.

[0035] This invention combines triphenyl thiophosphate with thiocarboxylic acid ester. Due to the highly active ester groups in the thiocarboxylic acid ester molecule, it exhibits excellent adsorption properties on metal surfaces, thus improving the high-temperature lubricity of the oil. The combined use of these two compounds ensures a reasonable sulfur-to-phosphorus ratio, avoiding the corrosion and wear problems associated with the use of sulfurized isobutylene in traditional lubricating oils. This improves the extreme pressure anti-wear performance and thermal stability of the lubricating oil composition, while simultaneously reducing corrosion to copper.

[0036] This invention uses a mixture of octyl-N-phenyl-α-naphthylamine, thiooctyl-N-phenyl-α-naphthylamine, and dithiooctyl-N-phenyl-α-naphthylamine as an antioxidant, effectively controlling the increase in oil viscosity at high temperatures while also exhibiting good oil solubility. This invention introduces sulfur into the antioxidant system, giving it certain extreme pressure properties, avoiding the problem of insufficient extreme pressure performance caused by using octyl-N-phenyl-α-naphthylamine alone as an antioxidant in traditional lubricating oils. The mixed antioxidant used in this invention significantly extends the service life of the oil while effectively improving its load-bearing capacity, meeting the lubrication requirements of electric drive axles in commercial vehicles under heavy loads and long-term use.

[0037] The transmission lubricating oil composition provided by this invention achieves a grade greater than 12 in FZG (A10 / 16.6R / 90) testing, while achieving a grade of 1 in long-cycle copper strip corrosion testing (150℃, 168h), and exhibiting a wear amount of less than 1mg in FE8 bearing testing (80℃, 80KN, 7.5rpm, 80h). This transmission lubricating oil composition possesses excellent electrochemical properties, load-bearing capacity, bearing protection performance, oxidation stability, and deposit control capabilities, making it suitable for lubricating integrated electric drive axle gearboxes in commercial vehicles and effectively extending the service life of the oil. Detailed Implementation

[0038] The embodiments of the present invention are described in detail below: The embodiments of the present invention are implemented under the premise of the technical solution of the present invention, and detailed implementation methods and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. The process parameters in the following embodiments that do not specify specific conditions are generally in accordance with conventional conditions.

[0039] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0040] The raw materials used in the embodiments of this invention are: TPPT (Irgalube TPPT produced by BASF); T202 (Wuxi Southern Petroleum Additives Co., Ltd.); T205 (Wuxi Southern Petroleum Additives Co., Ltd.); sulfurized isobutylene (T321H produced by Ningxia Tianhe Additives Co., Ltd.); alkylbenzene sulfonate calcium (T107 produced by Wuxi Southern Petroleum Additives Co., Ltd.); magnesium sulfonate (AR107 ultra-high base value alkylbenzene sulfonate produced by Anhui Aorun New Materials Co., Ltd.); polyisobutylene succinimide (T161R produced by Xinxiang Ruifeng New Materials Co., Ltd.); polyacrylate antifoaming agent (H2030 produced by Afton); PMA type dispersibility viscosity index improver (V12-095 produced by Evonik Additives Co., Ltd.); API Group III VHVI 6 base oil (YOUBASE produced by SK Corporation of Korea). 6) API Group III VHVI 3 base oil (YOUBASE 3 produced by SK Corporation of South Korea); API Group III VHVI 10 base oil (Daqing Refining & Chemical Company of China National Petroleum Corporation); mPAO 65 (Mobil Oil Company), PAO 100 base oil (Mobil Oil Company).

[0041] Example 1

[0042] The following ingredients are added: 0.5 wt% TPPT, 1.25 wt% di-n-butyl monothiodide (1,4-cyclohexanecarboxylic acid), 1.20 wt% T202, 0.40 wt% T205, 1.45 wt% calcium alkylbenzene sulfonate with a base number (TBN) of 405, 2.0 wt% polyisobutylene succinimide with a molecular weight of 3200-3500, 0.2 wt% octyl-N-phenyl-α-naphthylamine, 0.1 wt% monothiooctyl-N-phenyl-α-naphthylamine, 0.1 wt% dithiooctyl-N-phenyl-α-naphthylamine, 0.01 wt% polyacrylate-type antifoaming agent with a molecular weight of 60000, and 15.0 wt% PAO. 100 and 50.5 wt% of API Group III VHVI6 base oil, 20.5% of API Group III VHVI3 base oil, and 6.79% of PMA-type dispersibility viscosity index improver V12-095 were mixed evenly to prepare transmission lubricant composition (I). The performance test results are shown in Table 1.

[0043] Comparative Example 1

[0044] Except for the substitution of 1.25 wt% di-n-butyl monothiodi(1,4-cyclohexane) with 0.62 wt% di-n-butyl monothiodi(1,4-cyclohexane) and 0.63 wt% isobutylene sulfide, the rest are the same as the transmission lubricant composition (I), and the performance test results are shown in Table 1.

[0045] Comparative Example 2

[0046] Except for 1.25 wt% di-n-butyl monothiodide (1,4-cyclohexanecarboxylic acid) which was replaced by 1.25 wt% isobutylene sulfide, the rest were the same as the transmission lubricant composition (I), and the performance test results are shown in Table 1.

[0047] Table 1 Performance test data of Example 1, Comparative Example 1, and Comparative Example 2

[0048]

[0049]

[0050] As shown in Table 1, compared with Comparative Example 1, Composition (Ⅰ) exhibits superior high extreme pressure performance and excellent copper corrosion protection. This indicates that the compounding of triphenyl thiophosphate and thiocarboxylic acid ester anti-wear agent in a certain proportion produces a good synergistic effect, which is beneficial to improving the oil's load-bearing capacity, anti-wear performance, and copper corrosion protection performance, especially significantly improving bearing protection performance. Compared with Comparative Example 2, the use of TPPT and thiocarboxylic acid ester anti-wear agent in a certain proportion to replace traditional sulfurized isobutylene is beneficial to improving the oil's anti-wear performance and can also overcome the problems of copper corrosion and excessive bearing wear caused by the use of sulfurized isobutylene.

[0051] Example 2

[0052] The following ingredients were added: 0.2 wt% TPPT, 1.0 wt% di-n-butyl dithiodi(1,3-cyclohexanecarboxylic acid), 0.67 wt% T202, 0.33 wt% T205, 1.95 wt% magnesium sulfonate with a base number (TBN) of 417, 1.5 wt% polyisobutylene succinimide with a molecular weight of 3200–3500, 0.3125 wt% octyl-N-phenyl-α-naphthylamine, and 0.0625 wt% monothiooctyl- The transmission lubricating oil composition (II) was prepared by uniformly mixing N-phenyl-α-naphthylamine, 0.125 wt% dithiooctyl-N-phenyl-α-naphthylamine, 0.03 wt% polyacrylate antifoaming agent with a molecular weight of 60,000, 25.0 wt% mPAO65, 64.6 wt% API Group III VHVI6 base oil and 4.22% PMA type dispersibility viscosity index improver V12-095. The performance test results are shown in Table 2.

[0053] Comparative Example 3

[0054] Except for the antioxidant component being replaced by 0.60 wt% octyl-N-phenyl-α-naphthylamine, the rest are the same as composition (II), and the performance test results are shown in Table 2.

[0055] Comparative Example 4

[0056] Except for the antioxidant component being replaced by 0.3 wt% monothiooctyl-N-phenyl-α-naphthylamine and 0.3 wt% dithiooctyl-N-phenyl-α-naphthylamine, the rest are the same as composition (II), and the performance test results are shown in Table 2.

[0057] Table 2 Performance test data of Example 2 and Comparative Examples 3 and 4

[0058]

[0059] As shown in Table 2, compared with Comparative Example 3, Composition (II) exhibits superior antioxidant and extreme pressure anti-wear properties, significantly reducing viscosity and acid value increases, effectively extending oil service life, and overcoming the problem of insufficient extreme pressure performance when using octyl-N-phenyl-α-naphthylamine alone. Compared with Comparative Example 4, the combination of octyl-N-phenyl-α-naphthylamine with thiooctyl-N-phenyl-α-naphthylamine and dithiooctyl-N-phenyl-α-naphthylamine in a certain proportion has a good synergistic effect, significantly reducing the increase in viscosity and acid value of oil at high temperatures (170℃), improving sludge control, and enhancing the overall extreme pressure performance of the oil formulation.

[0060] Example 3

[0061] The following ingredients are added: 0.375 wt% TPPT, 1.5 wt% di-n-butyl monothiodide (1,4-cyclohexanecarboxylic acid), 0.60 wt% T202, 0.60 wt% T205, 1.55 wt% calcium alkylbenzene sulfonate with a base number (TBN) of 405, 1.6 wt% polyisobutylene succinimide with a molecular weight of 3200-3500, 0.40 wt% octyl-N-phenyl-α-naphthylamine, 0.08 wt% monothiooctyl-N-phenyl-α-naphthylamine, 0.08 wt% dithiooctyl-N-phenyl-α-naphthylamine, 0.015 wt% polyacrylate-type antifoaming agent with a molecular weight of 60000, and 15.0 wt% PAO. 100, 32.5 wt% of API Group III VHVI10 base oil, 41.5% of API Group III VHVI3 base oil and 4.2% of PMA type dispersant viscosity index improver V12-095 were mixed evenly to prepare transmission lubricant composition (III), and its performance test results are shown in Table 3.

[0062] Example 4

[0063] The following ingredients were added: 0.3125 wt% TPPT, 1.5625 wt% di-n-butyl monothiodide (1,4-cyclohexanecarboxylic acid), 0.60 wt% T202, 0.60 wt% T205, 1.55 wt% calcium alkylbenzene sulfonate with a base number (TBN) of 405, 1.6 wt% polyisobutylene succinimide with a molecular weight of 3200-3500, 0.40 wt% octyl-N-phenyl-α-naphthylamine, 0.08 wt% monothiooctyl-N-phenyl-α-naphthylamine, 0.08 wt% dithiooctyl-N-phenyl-α-naphthylamine, 0.015 wt% polyacrylate-type antifoaming agent with a molecular weight of 60000, and 15.7 wt% PAO. 100, 32.0 wt% of API Group III VHVI10 base oil, 41.5% of API Group III VHVI3 base oil and 4.0% of PMA type dispersant viscosity index improver V12-095 were mixed evenly to prepare transmission lubricant composition (Ⅳ), and its performance test results are shown in Table 3.

[0064] Example 5

[0065] The following ingredients are added: 0.375 wt% TPPT, 1.5 wt% di-n-butyl monothiodide (1,4-cyclohexanecarboxylic acid), 0.90 wt% T202, 0.30 wt% T205, 1.55 wt% calcium alkylbenzene sulfonate with a base number (TBN) of 405, 1.6 wt% polyisobutylene succinimide with a molecular weight of 3200-3500, 0.40 wt% octyl-N-phenyl-α-naphthylamine, 0.08 wt% monothiooctyl-N-phenyl-α-naphthylamine, 0.08 wt% dithiooctyl-N-phenyl-α-naphthylamine, 0.015 wt% polyacrylate-type antifoaming agent with a molecular weight of 60000, and 14.5 wt% PAO. 100, 32.5 wt% of API Group III VHVI10 base oil, 42.3% of API Group III VHVI3 base oil and 3.9% of PMA type dispersibility viscosity index improver V12-095 were mixed evenly to prepare transmission lubricant composition (V), and its performance test results are shown in Table 3.

[0066] Table 3 Evaluation results of Examples 3, 4, and 5

[0067]

[0068]

[0069] As shown in Table 3, the test results of compositions (Ⅲ), (Ⅳ), and (Ⅴ) are as follows: the breakdown voltage (at room temperature) reaches over 70KV, FZG (A10 / 16.6R / 90) reaches level 12 or higher, the pitting test time of FZG exceeds 300 hours, the extended copper strip corrosion test (150℃, 168h) can reach level 1b, and the wear amount of the FE8 bearing test (80℃, 80KN, 7.5rpm, 80h) is less than 1mg.

[0070] The lubricating oil composition prepared in the embodiments of the present invention has excellent electrochemical properties, load-bearing capacity, bearing protection performance, oxidation stability, deposit control ability, and rubber compatibility. It is suitable for lubrication of commercial integrated electric drive axle gearboxes and can effectively protect drive motors, gear reducers, and controllers.

[0071] Although specific embodiments of the invention have been described in detail, those skilled in the art will understand that various modifications and substitutions can be made to those details based on all the teachings disclosed, and all such changes are within the scope of protection of this invention. The full scope of this invention is given by the appended claims and any equivalents thereof.

Claims

1. A transmission lubricating oil composition, characterized in that, The transmission lubricating oil composition comprises, by weight parts: Phosphorus-containing agent: 0.1~0.5 parts; Thiocarboxylic acid ester additive: 0.4~1.5 parts; Antioxidant: 0.3~0.6 parts; Antioxidant and anti-corrosion additives: 1.0~2.0 parts; Cleaning agent: 1.25~1.95 parts; Ashless dispersant: 1.5~2.5 parts; Antifoaming agent: 0.005~0.03 parts; Base oil: Balance; The phosphorus-containing agent is triphenyl thiophosphate; The thiocarboxylic acid ester additive is a monothiodicarboxylic acid dialkyl ester or a dithiodicarboxylic acid dialkyl ester. The thiocarboxylic acid ester additive has the following general structural formula: Wherein, R1 is a straight-chain butyl or a straight-chain octyl, R2 is at least one of 1,3-cyclohexyl or 1,4-cyclohexyl, and n is 1 or 2; The antioxidant is a mixture of octyl-N-phenyl-α-naphthylamine, monothiooctyl-N-phenyl-α-naphthylamine, and dithiooctyl-N-phenyl-α-naphthylamine.

2. The transmission lubricating oil composition according to claim 1, characterized in that, The thiocarboxylic acid ester additive is at least one of the following: di-n-butyl monothiodide (1,3-cyclohexanecarboxylic acid), di-n-butyl monothiodide (1,3-cyclohexanecarboxylic acid), di-n-octyl monothiodide (1,3-cyclohexanecarboxylic acid), di-n-butyl monothiodide (1,4-cyclohexanecarboxylic acid), di-n-butyl monothiodide (1,4-cyclohexanecarboxylic acid), di-n-octyl monothiodide (1,4-cyclohexanecarboxylic acid), and di-n-octyl monothiodide (1,4-cyclohexanecarboxylic acid).

3. The transmission lubricating oil composition as described in claim 1, characterized in that, The mass ratio of the triphenyl thiophosphate to the thiocarboxylic acid ester additive is (0.2~0.4):

1.

4. The transmission lubricating oil composition according to claim 3, characterized in that, The mass ratio of the triphenyl thiophosphate to the thiocarboxylic acid ester additive is 0.25:

1.

5. The transmission lubricating oil composition as claimed in claim 1, characterized in that, The mass ratio of octyl-N-phenyl-α-naphthylamine, monothiooctyl-N-phenyl-α-naphthylamine, and dithiooctyl-N-phenyl-α-naphthylamine is 1:(0.2~0.5):(0.2~0.5).

6. The transmission lubricating oil composition according to claim 1, characterized in that, The antioxidant and anti-corrosion additive is a mixture of T202 and T205.

7. The transmission lubricating oil composition according to claim 6, characterized in that, The mass ratio of T202 to T205 is (1~3):

1.

8. The transmission lubricating oil composition as claimed in claim 6, characterized in that, The mass ratio of T202 to T205 is 1:

1.

9. The transmission lubricating oil composition according to claim 1, characterized in that, The ashless dispersant is polyisobutylene succinimide with a molecular weight greater than 3000.

10. The transmission lubricating oil composition according to claim 1, characterized in that, The base oil is a mixture of PMA-type viscosity index improver, polyalphaolefin, and API Group III mineral base oil.

11. The transmission lubricating oil composition as claimed in claim 10, characterized in that, The polyalphaolefin is PAO100 base oil or mPAO65 base oil.

12. The transmission lubricating oil composition as claimed in claim 10, characterized in that, The kinematic viscosity of the API Group III mineral base oil is 3~10 cSt.

13. The transmission lubricating oil composition according to claim 1, characterized in that, The detergent is at least one of calcium alkylbenzene sulfonate with an alkalinity greater than 300 and magnesium sulfonate with an alkalinity greater than 400.

14. The transmission lubricating oil composition according to claim 1, characterized in that, The antifoaming agent is a polyacrylate-type antifoaming agent with a molecular weight of 60,000.

15. The transmission lubricating oil composition according to any one of claims 1 to 14, characterized in that, The composition comprises, by weight parts: Phosphorus-containing agent: 0.2~0.5 parts; Thiocarboxylic acid ester additive: 0.8~1.5 parts; Antioxidant: 0.4~0.6 parts; Antioxidant and anti-corrosion additives: 1.0~1.6 parts; Cleaning agent: 1.45~1.95 parts; Ashless dispersant: 1.5~2.0 parts; Antifoaming agent: 0.01~0.03 parts; Base oil: Balance.

16. A method for preparing the transmission lubricating oil composition according to any one of claims 1 to 15, characterized in that, The method includes: Add the phosphorus-containing agent, thiocarboxylic acid ester additive, antioxidant, antioxidant and anti-corrosion additive, detergent, ashless dispersant, antifoaming agent and base oil into a container according to the ratio, and mix at 50~60℃ for 2 hours until all components are uniformly dissolved.

17. The use of the transmission lubricating oil composition according to any one of claims 1 to 15 in an integrated electric drive axle for commercial vehicles.

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