Grease Composition for Rolling Bearings High Temperature Noise
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Solution Overview
Problem
Conventional grease compositions for rolling bearings fail to maintain low noise performance over an extended period at high temperatures, and can impair the sealing performance by swelling rubber or resin sealing members.
Innovation Solution
A grease composition combining a base oil with an aniline point of 110°C or more, a diurea compound as the thickener, and a metal deactivator, such as benzotriazole, to improve bearing life and maintain low noise performance without affecting sealing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If lithium soap is used as the thickener, then the noise performance of the bearing is relatively improved, but the durability at high temperatures is insufficient and the sealing member swells
Solution Approach 1:
The patent changes the chemical composition parameters by replacing lithium soap with specific diurea compounds (containing fibrous materials with fiber length of at least 3 μm) and selecting base oils with aniline points of 100°C or more. This parameter change resolves the contradiction by achieving both low noise performance and high temperature durability simultaneously, while preventing sealing member swelling.
Solution Approach 2:
The patent employs a composite grease formulation combining diurea compounds with fibrous materials, specific base oils (ester type synthetic oils, synthetic hydrocarbon oils, or mineral oils), and metal deactivators. This composite approach integrates multiple functional components to achieve both noise reduction and high temperature stability without compromising sealing performance.
2Reliability
If diurea compounds are used as the thickener, then the durability at high temperatures is improved, but the bearing life that secures low noise performance at high temperatures for extended periods is insufficient
Solution Approach 1:
The patent optimizes specific parameters including the fiber length of fibrous materials (at least 3 μm), the aniline point of base oils (100°C or more), and the inclusion of metal deactivators. These parameter optimizations extend the duration of low noise performance at high temperatures by preventing grease degradation and maintaining stable lubrication films over extended bearing life.
Solution Approach 2:
The patent introduces metal deactivators as intermediary substances that prevent metal catalyzed degradation of the grease components. This intermediary action protects the diurea compound-thickened grease from breaking down at high temperatures, thereby extending the bearing life that maintains low noise performance.
3Ease of manufacture
If conventional grease compositions are used, then the initial noise performance is acceptable, but the sealing performance is impaired due to swelling of the sealing member
Solution Approach 1:
The patent changes the chemical compatibility parameters by selecting base oils with aniline points of 100°C or more and using diurea compounds as thickeners. These parameter changes ensure the grease is chemically compatible with rubber and resin sealing members, preventing swelling and maintaining sealing performance while achieving low noise operation.
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 grease composition significantly enhances bearing life with low noise performance at high temperatures while preserving sealing integrity, preventing contamination and leakage for an extended period.
Implementation Method 1
The sliding surface of the bearing is lubricated with an oil film formed by the grease composition
Implementation Method 2
a metal deactivator... to improve bearing life and maintain low noise performance
Data Source
AI summary
The invention provides a grease composition for rolling bearings that can exhibit improved bearing life that can secure the low noise performance under high temperature conditions, and a rolling bearing where the above-mentioned grease composition is enclosed. The grease composition for rolling bearings includes a base oil, a urea thickener and a metal deactivator. The base oil has an aniline point of 110° C. or more. The urea thickener is at least one kind of diurea compound selected from the group consisting of diurea compounds represented by formula (1): R1—NHCONH—R2—NHCONH—R3 (wherein R1 and R3, which may be the same or different from each other represent a C6-30alkyl group, a C5-8cycloalkyl group or a C6-10aryl group, and R2 represents a bivalent aromatic hydrocarbon group having 6 to 15 carbon atoms.)