Low Viscosity Electric Motor Lubricant Additive Package
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Solution Overview
Problem
Developing electric motor lubricants for electric or hybrid-electric vehicles that balance low viscosity with high wear and friction performance, oxidative stability, and low electrical conductivity is challenging, particularly for lubricants with kinematic viscosity (kV100° C.) of 4.5 cSt or less, as they often require additional antiwear additives that increase conductivity and decrease stability.
Innovation Solution
A lubricating fluid comprising base oils, a succinimide dispersant derived from high molecular weight polyisobutylene, an amine salt of a phosphoric acid ester, an ashless dialkyl dithiophosphate, and a sulfur-providing thiadiazole additive, which together achieve low viscosity while maintaining wear protection, oxidative stability, and low conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the lubricant viscosity is lowered to improve efficiency, then energy loss is reduced, but wear and friction performance deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the lubricant by incorporating specific additives (succinimide dispersant, amine salt of phosphoric acid ester, ashless dialkyl dithiophosphate, and thiadiazole sulfur-providing additive) to achieve the optimal balance between low viscosity and adequate wear protection. This allows the base oil to maintain low viscosity while additives provide necessary protective functions.
Solution Approach 2:
The patent creates a composite lubricant formulation by combining multiple additive components with specific functional properties. The synergistic interaction between the dispersant, phosphoric acid ester salt, dithiophosphate, and thiadiazole compounds produces a lubricant that achieves both low viscosity and high wear protection performance that cannot be obtained with single additives.
2Reliability
If antiwear additives are added to low viscosity lubricants to improve wear performance, then reliability is improved, but electrical conductivity increases
Solution Approach 1:
The patent carefully controls the concentration and type of antiwear additives to maintain electrical conductivity within acceptable limits. By selecting ashless dialkyl dithiophosphate and controlling the phosphorus content from phosphoric acid ester salts, the lubricant achieves adequate wear protection while limiting conductivity increase that would harm electrified components.
3Reliability
If antiwear additives are added to low viscosity lubricants to improve wear performance, then reliability is improved, but oxidative stability deteriorates
Solution Approach 1:
The patent selects ashless dialkyl dithiophosphate and controls additive concentrations to minimize oxidative degradation. The ashless nature of the dithiophosphate and the controlled phosphorus content from phosphoric acid ester salts help maintain oxidative stability while providing necessary antiwear protection.
Solution Approach 2:
The patent uses sacrificial additives like the thiadiazole sulfur-providing compound and dithiophosphate that form protective films on metal surfaces, consuming themselves in the process. These additives preferentially react with metal surfaces and oxidize instead of the base oil, thereby protecting the main lubricant from oxidation while providing wear protection.
4Loss of energy
If the lubricant viscosity is lowered to improve efficiency, then energy loss is reduced, but the ability to pass severe wear tests deteriorates
Solution Approach 1:
The patent formulates a composite additive package specifically designed to enable low viscosity lubricants to pass severe wear tests like FZG A10/16.6R/90. The combination of succinimide dispersant, amine salt of phosphoric acid ester, ashless dialkyl dithiophosphate, and thiadiazole sulfur-providing additive creates synergistic effects that provide adequate extreme pressure and antiwear protection even at viscosities of 4.5 cSt or lower.
Data Source
AI summary
An electric motor lubricating fluid for an electric motor system including a lubricating base oil, at least one sulfurized component, at least two phosphorus-providing additives, and at least one high molecular weight dispersant. The electric motor lubricating fluid provides acceptable wear performance as well as good electrical conductivity and oxidative stability for use in electric motor system fluids having a low viscosity.