A base oil composition for transmission lubricating oil and use thereof

Abstract

The present application relates to the technical field of lubricating oil base oil, and particularly relates to a base oil composition for gearbox lubricating oil and application.The lubricating oil composition comprises base oil I, base oil II and base oil III, the ratio of the total naphthenic hydrocarbon mass percentage and the total paraffin mass percentage of the lubricating oil composition is greater than 0.05, and the total aromatic hydrocarbon mass percentage is less than 0.3%.The scheme of the lubricating oil composition provided by the present application can balance the extreme pressure performance and the anti-wear performance, has excellent anti-pitting and micro-pitting performance, and also has excellent insulation electrical protection and good heat dissipation and cooling performance, and more importantly, has reliable compatibility with motor materials, and is suitable for pure electric vehicle and hybrid vehicle gearbox lubrication.

Description

Technical Field

[0001] This invention relates to the field of lubricating oil technology, and more particularly to a base oil composition for transmission lubricating oil and its application. Background Technology

[0002] The integrated development of powertrain technology for pure electric vehicles and hybrid electric vehicles is an important trend in automotive development. The integration of motors and gearboxes is currently the mainstream technology for transmission systems, and the lubrication and cooling methods adopt an "integrated" solution for motors and gearboxes.

[0003] Compared to traditional car transmissions, pure electric vehicles and hybrid vehicles add an electric motor to their transmissions. This motor is immersed in lubricating oil, which cools the motor. The motor system and transmission system use the same lubricating oil. The lubricating oil used must possess reliable insulation and heat dissipation properties, good compatibility with motor materials, and adequate lubrication and protection for gears and bearings.

[0004] Different base oils differ significantly in structure and composition, resulting in insufficient compatibility with relevant motor materials and an inability to simultaneously meet the balanced requirements for extreme pressure resistance of gears and friction and wear resistance of bearings. Using a single base oil component cannot satisfy the comprehensive performance requirements of integrated motor oil cooling and lubrication systems such as motors and gearboxes.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a base oil composition for transmission lubricants and its application. The lubricant composition provided by this invention solves systemic problems in transmission lubricants for pure electric vehicles and hybrid vehicles, such as insufficient lubrication and protection of gear shafts, poor insulation performance, and material incompatibility.

[0007] Specifically, this invention investigated the causes of the aforementioned technical problems and found that they are due to the significant differences in structure and composition among different base oils, resulting in insufficient compatibility with relevant motor materials and an inability to simultaneously meet the balanced requirements for gear anti-extrusion performance and bearing friction and wear resistance. Using a single or conventionally combined base oil component cannot meet the comprehensive performance requirements of integrated motor oil cooling and lubrication systems such as motors and gearboxes.

[0008] In a first aspect, the present invention provides a base oil composition for transmission lubricating oil, comprising base oil I, base oil II, and base oil III, wherein the ratio of the total cycloalkanes to the total alkanes in the lubricating oil composition is greater than 0.05, and the total aromatics in the lubricating oil composition are less than 0.3%. The lubricating oil composition used in this invention is suitable for transmission lubrication in pure electric vehicles and hybrid electric vehicles, solving systemic problems such as insufficient lubrication protection of gear shafts, poor insulation performance, and material incompatibility in transmission lubricating oils for pure electric vehicles and hybrid electric vehicles. It is a transmission lubricating oil for new energy vehicles and intelligent connected vehicles that can simultaneously provide lubrication protection for gears and bearings, excellent insulation performance, cooling performance, and reliable motor material compatibility.

[0009] Preferably, the mass ratio of base oil I, base oil II and base oil III is 1:1 to 30:30 to 95, and more preferably, the mass ratio of base oil I, base oil II and base oil III is 1:2 to 20:35 to 90.

[0010] More preferably, the ratio of the total cycloalkanes to the total alkanes in the lubricating oil composition is 5%–50%:40%–80%, and the total aromatics in the lubricating oil composition is 0%–0.2%.

[0011] In this invention, by using base oils of specific types and parameters and proportions for blending, the polarity of the lubricating oil can be balanced, thereby achieving better lubrication and protection for gears and bearings.

[0012] More preferably, the lubricating oil composition has a thermal conductivity (40°C) ≥ 0.120 W / (m·K) and a volume resistivity (25°C) ≥ 100 MΩ·m; and / or,

[0013] The viscosity index of the lubricating oil composition is 90-150, the pour point is ≤-30℃, and the kinematic viscosity at 100℃ is 2-5 mm. 2 / s.

[0014] Preferably, the base oil I is a synthetic hydrocarbon fluid, preferably including one or more of natural gas-derived oil, coal-derived oil, and polyalphaolefins.

[0015] Preferably, the base oil II is a synthetic ester fluid, preferably including one or more of monoesters, diesters, and polyol esters.

[0016] Preferably, the base oil III is a mineral-based hydrogenated hydrocarbon fluid, and preferably includes one or more of HVI I, HVI II, and HVI III base oils.

[0017] Secondly, the present invention provides the application of the aforementioned base oil composition for transmission lubricating oil, particularly in the lubrication of transmissions in pure electric vehicles and hybrid electric vehicles, preferably in integrated electric drive transmission systems for cooling motor lubricating oil.

[0018] The base oil composition provided by this invention can balance anti-wear performance, has excellent anti-pitting and micro-pitting properties, as well as excellent electrical insulation and good heat dissipation and cooling performance. More importantly, it has reliable compatibility with motor materials and is suitable for lubrication of transmissions in pure electric vehicles and hybrid electric vehicles.

[0019] The beneficial effects of the present invention are at least as follows: the base oil composition for lubricating oil suitable for the transmission lubrication of pure electric vehicles and hybrid electric vehicles provided by the present invention achieves lubrication protection for gears and bearings in the transmission system of pure electric vehicles and hybrid electric vehicles, while having excellent cooling performance, insulation performance and reliable material compatibility, ensuring the reliable safety of electric drive. Detailed Implementation

[0020] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention. All raw materials used in the examples are commercially available materials, and the technical means used in the examples are conventional means well known to those skilled in the art.

[0021] In this embodiment of the invention, regarding the basic properties of the oil, kinematic viscosity was tested using GB / T 265 "Determination of Kinematic Viscosity and Calculation of Dynamic Viscosity of Petroleum Products", viscosity index was tested using GB / T 1995 "Calculation of Viscosity Index of Petroleum Products", and pour point was tested using GB / T 3535 "Determination of Pour Point of Petroleum Products". Regarding oil characteristics, the fatigue life of gears was evaluated through gearbox durability tests, assessing the reliability of the lubricating oil's lubrication and protection of gears; the performance indicator reflected was the durability failure time. The fatigue life of needle roller bearings was evaluated, assessing the oil's lubrication and protection of bearings, primarily reflecting the anti-friction performance of the lubricating oil. The total rotational speed at which the monitored vibration exceeded a certain level during the test was defined as the bearing fatigue life, and the 50% failure probability time (L50) was recorded. The volume resistivity of the oil was tested using GB / T 5654-2007 "Measurement of Relative Permeability, Dielectric Loss Factor and DC Resistivity of Liquid Materials" to evaluate the oil's insulation performance. The thermal conductivity of the oil was tested using ASTM D7896, "Standard Test Method for Determining Thermal Conductivity, Thermal Diffusivity and Volumetric Heat Capacity of Engine Coolants and Related Fluids by Transient Hot-Wire Liquid Thermal Conductivity Method," to evaluate its cooling performance. The compatibility of the oil with materials was evaluated using NB / SH / T 0877, "Lubricating Oil Rubber Compatibility Test Method."

[0022] Examples 1-5 and Comparative Examples 1-2

[0023] The mass percentage and performance of the base oil compositions for lubricating oils suitable for transmissions of pure electric vehicles and hybrid electric vehicles described in Examples 1-5 and Comparative Examples 1-2 of this invention are shown in Table 1.

[0024] As shown in Table 1, in Comparative Example 1, the ratio of cycloalkanes to alkanes by mass fraction was 0.02, indicating a low cycloalkanes content and a small amount of highly polar components in the base oil, which negatively impacted bearing durability. Furthermore, significant volume shrinkage was observed in rubber material compatibility. This was due to insufficient highly polar cycloalkanes in the base oil, causing the release of polar filler oil from the rubber and resulting in shrinkage. In Comparative Example 2, the total aromatics content was 10%. Compared to Examples 1-5, the durability of gears and bearings was significantly reduced, and the lower thermal conductivity affected cooling performance. Examples 1-5 exhibited a more balanced overall performance, considering both gear and shaft lubrication and durability protection, and possessing excellent insulation, cooling performance, and reliable material compatibility, ensuring reliable and safe oil performance.

[0025] Table 1. Composition and performance of lubricating oil compositions in Examples 1-5 and Comparative Examples 1-2

[0026]

[0027]

[0028] Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. Use of a base oil composition for a transmission lubricating oil, characterized in that, The application is applied to lubrication of gearbox of pure electric vehicle and hybrid electric vehicle, the base oil composition comprises base oil I, base oil II and base oil III, the ratio of total naphthenic hydrocarbon mass percentage and total paraffin mass percentage of the base oil composition is 0.67-0.74, the total aromatic hydrocarbon mass percentage of the base oil composition is less than 0.3%. The mass ratio of the base oil I, the base oil II and the base oil III is 1:1-30:30-95. The base oil I is synthetic hydrocarbon fluid. The base oil II is synthetic ester fluid, and the base oil III is mineral hydrogenated hydrocarbon fluid.

2. The use of the base oil composition for transmission lubricating oil according to claim 1, characterized by The total aromatic hydrocarbon mass percentage of the base oil composition is 0-0.2%.

3. The use of the base oil composition for transmission lubricating oil according to claim 1, characterized by, The mass ratio of the base oil I, the base oil II and the base oil III is 1:2-20:35-90.

4. The use of the base oil composition for transmission lubricating oil according to claim 3, characterized by The thermal conductivity coefficient of the base oil composition at 40 DEG C is greater than or equal to 0.120 W / m.k. and / or, the base oil composition has a viscosity index of 90 to 180, a pour point of -30°C or less, and a kinematic viscosity at 100°C of 2 to 5 mm 2 / s. 5.The application of base oil composition for gearbox lubricating oil according to claim 1, characterized in that, The base oil I comprises one or more of natural gas oil, coal oil and poly-alpha-olefin; And / or, the base oil II comprises one or more of monoester, diester and polyol ester oil; And / or, the base oil III comprises one or more of HVI I, HVI II and HVI III base oil.

6. The use of the base oil composition for transmission lubricating oil according to claim 1, characterized by Integrated electric drive gearbox system for lubricating oil cooling of electric motor.

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