Biodegradable Ester Transmission Fluid for Electric Vehicles
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Solution Overview
Problem
The development of lubricant fluids for electric vehicles is challenging due to the unique operating conditions of high torques at low speeds, high speeds, and low temperatures, as well as the integration of electric motors into the transmission, which requires specialized additives and viscosity modifiers not easily addressed by existing technologies.
Innovation Solution
A lubricating composition comprising at least 70 wt% biodegradable ester base oil with specific kinematic viscosity and high viscosity esters, combined with anti-foam additives, provides improved lubrication, reduced friction, and enhanced thermal conductivity, optimized for electric vehicle transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transmission fluids are used in electric vehicles, then the fluid composition can be simplified, but the fluid fails to meet the specific lubrication requirements under high torque at low speeds and high speed operating conditions
Solution Approach 1:
The patent modifies the base oil composition by using ester-based oils with specific viscosity ranges (4-8 cSt at 100°C) and adds viscosity index improvers to achieve the desired viscosity characteristics across different operating temperatures and speeds, thereby optimizing lubrication performance for EV transmission conditions
Solution Approach 2:
The transmission fluid employs a composite formulation combining ester base oils, viscosity index improvers, and specialized additives in specific proportions to create a multi-functional fluid that simultaneously provides lubrication, cooling, and protection under varying operational conditions of electric vehicle transmissions
2Reliability
If the transmission fluid is optimized for high torque at low speeds, then lubrication performance improves, but thermal management capability deteriorates
Solution Approach 1:
The patent carefully selects base oils with specific viscosity-temperature characteristics and adds viscosity index improvers to maintain appropriate viscosity across a wide temperature range, ensuring both high-torque lubrication capability and thermal management effectiveness through optimized fluid rheology
3Productivity
If the transmission fluid is optimized for high speeds, then efficiency improves, but lubrication under high torque at low speeds deteriorates
Solution Approach 1:
The patent uses viscosity index improvers to create a non-Newtonian fluid behavior that provides lower viscosity at high speeds for reduced friction and higher viscosity at low speeds for adequate lubrication film formation, thereby optimizing performance across the entire operating range
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The lubricating composition achieves improved efficiency and reduced heat production, with lower operational temperatures and increased thermal conductivity, leading to enhanced drivetrain performance and efficiency gains in electric vehicle transmissions.
Implementation Method 1
A lubricating composition comprising at least 70 wt% biodegradable ester base oil
Implementation Method 2
at least 0.5 wt % and no more than 10 wt % of a viscosity index improver which is at least one high viscosity ester
Implementation Method 3
an anti-foam additive selected from silicone oil based antifoam additives and polyacrylate antifoam additives
Implementation Method 4
enhanced thermal conductivity, leading to enhanced drivetrain performance and efficiency gains
Data Source
AI summary
Implementations of the disclosed subject matter provide a lubricating composition for use as a transmission fluid in an electric vehicle. The lubricating composition may include at least 70 wt %, based on the overall weight of the lubricating composition, of a biodegradable ester base oil with a kinematic viscosity at 100° C. in the range of 2.5 to 7.0 mm2/s. The ester is biodegradable according to OECD test guidelines series 301. The composition may also include at least 0.5 wt % and no more than 10 wt %, based on the overall weight of the lubricating composition, of a viscosity index improver which is at least one high viscosity ester with a kinematic viscosity at 100° C. of at least 1000 mm2/s; an anti-foam additive selected from silicone oil based antifoam additives and polyacrylate antifoam additives. Also disclosed is a process for lubricating an electric vehicle drive train comprising a transmission by applying the lubricating composition to the transmission.