Biodegradable Grease for Wind Turbine Bearings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current grease compositions for aerogenerators lack biodegradability and fretting resistance, posing environmental risks and performance issues when leaked into natural environments.
Innovation Solution
A biodegradable grease composition using an ester oil with a kinematic viscosity of 60 to 160 mm²/s and a diurea compound thickener, obtained by reacting an amine mixture of 4-8C alicyclic and 20-24C aliphatic monoamines with a diisocyanate, along with a phosphorus-based antiwear agent, to enhance fretting resistance, extreme pressure, and low temperature properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional grease composition is used for aerogenerator bearings, then lubrication performance is maintained, but biodegradability is poor and environmental contamination occurs when leaked
Solution Approach 1:
The patent changes the chemical composition parameters of the base oil by specifying ester oils with particular viscosity ranges (10-70 mm²/s at 40°C) and using specific thickener compounds (polyurea, polyisocyanurate, or their mixtures) to achieve both environmental compatibility and functional performance. This parameter optimization resolves the contradiction between maintaining lubrication reliability and improving biodegradability.
Solution Approach 2:
The patent employs composite material strategies by combining specific ratios of ester oils with multiple thickener types (polyurea and/or polyisocyanurate) to create a grease composition that simultaneously achieves biodegradability, fretting resistance, and extreme pressure properties. The composite formulation allows the grease to meet environmental standards while maintaining operational reliability.
2Reliability
If a grease composition with high biodegradability is used, then environmental impact is reduced, but fretting resistance deteriorates due to micro-oscillation in aerogenerator bearings
Solution Approach 1:
The patent optimizes the viscosity parameter of the base oil (ester oil with 10-70 mm²/s at 40°C) and the chemical structure parameters of the thickeners to achieve a balance where the grease maintains adequate film strength for fretting resistance while remaining biodegradable. The specific viscosity range and thickener selection prevent both excessive thinning (which would harm fretting resistance) and excessive thickness (which would harm biodegradability).
Solution Approach 2:
The patent uses composite thickener systems combining polyurea, polyisocyanurate, or their mixtures with ester oils to create a material that provides enhanced boundary lubrication for fretting protection while maintaining biodegradability. The synergistic interaction between the thickener and base oil components achieves both contradictory requirements simultaneously.
3Strength
If a grease composition with high viscosity is used to improve extreme pressure property, then load carrying capacity increases, but low temperature property deteriorates
Solution Approach 1:
The patent carefully controls the viscosity parameter of the ester oil base within the range of 10-70 mm²/s at 40°C to achieve an optimal balance. This viscosity range provides sufficient film strength for extreme pressure conditions while preventing excessive viscosity that would harm low-temperature fluidity and pumpability. The controlled viscosity parameter resolves the contradiction between load carrying capacity and low-temperature performance.
Solution Approach 2:
The patent applies local quality by having the grease provide different effective viscosities under different operating conditions: at high loads and temperatures, the grease maintains adequate viscosity for extreme pressure protection, while at low temperatures, the controlled base viscosity ensures proper flow and distribution. The additive package and thickener system enhance this local adaptation capability.
Data Source
AI summary
An object of the present invention is to provide a biodegradable grease composition which is excellent in fretting resistance, extreme pressure property, low temperature property, and biodegradability as well, and has a small effect to the environment even if released to a natural environment. The grease composition comprises a base oil composed of an ester oil having a kinematic viscosity at 40°C of 60 to 160 mm2/s and a thickener composed of a diurea compound obtained by allowing an amine mixture comprising a 4-8C alicyclic monoamine and a 20-24C aliphatic monoamine to react with a diisocyanate compound, wherein a content molar ratio of the alicyclic monoamine and the aliphatic monoamine in the amine mixture is 7:3 to 9:1, the content of the thickener in a total amount of the base oil and the thickener is 7 to 11 % by mass and a penetration is 265 to 340.