Bearing Grease Composition for Heat and Hydrogen Flaking Resistance
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Solution Overview
Problem
Conventional grease compositions for automotive electrical equipment and auxiliaries fail to extend bearing lubrication life at elevated temperatures and prevent hydrogen embrittlement-induced flaking, as they lack effective measures to prevent hydrogen penetration into metal surfaces.
Innovation Solution
A grease composition using alkyldiphenyl ether oil as the base, a diurea compound as the thickener, zinc or calcium sulfonate as the anti-flaking additive, and a combination of amine and phenol antioxidants, without nitrites, organic antimony, or molybdenum compounds, to enhance heat resistance and prevent hydrogen embrittlement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional greases (lithium soap or diurea greases with mineral oil or synthetic hydrocarbon oil) are used, then cost is reduced and basic lubrication is provided, but heat resistance is insufficient and flowability toward bearing portions is poor
Solution Approach 1:
The patent changes the chemical parameters of the base oil by using alkyldiphenyl ether oil instead of conventional mineral oil or synthetic hydrocarbon oil. This parameter change provides superior heat resistance and oxidation stability while maintaining appropriate viscosity and flowability for bearing lubrication.
Solution Approach 2:
The patent creates a composite grease formulation by combining alkyldiphenyl ether oil as the base oil with diurea thickener and specific additives (calcium or zinc sulfonate, phenolic antioxidants). This composite material achieves both high heat resistance and good flowability that neither component could provide alone.
2Reliability
If anti-flaking additives (nitrites or oxidizers for passivation) are added to oxidize the metal surface and inhibit catalytic action, then hydrogen generation from lubricant decomposition is prevented, but the addition decreases lubrication life at high temperatures
Solution Approach 1:
The patent converts the harmful effect of metal surface oxidation into a beneficial protective mechanism. By using calcium or zinc sulfonate additives, a protective film is formed on the metal surface that prevents hydrogen penetration while the alkyldiphenyl ether oil and phenolic antioxidants prevent the oxidation from degrading the lubricant, thus extending lubrication life.
Solution Approach 2:
The patent introduces calcium or zinc sulfonate as an intermediary substance that forms a protective barrier between the metal surface and hydrogen. This intermediary film prevents hydrogen penetration into the metal while the phenolic antioxidants protect the lubricant from oxidation, allowing the system to achieve both hydrogen embrittlement resistance and extended lubrication life.
3Reliability
If phenyl ether type synthetic oil or fluorinated polymer oil is used as base oil, then hydrogen generation from lubricant decomposition is prevented, but flowability toward bearing portions and heat resistance remain insufficient
Solution Approach 1:
The patent optimizes the viscosity and chemical structure parameters of the base oil by selecting alkyldiphenyl ether oil with specific molecular weight and structure. This provides the right balance between flowability for bearing penetration and heat resistance, while the calcium or zinc sulfonate additives further enhance protection against hydrogen embrittlement.
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 achieves long lubrication life and excellent resistance to hydrogen embrittlement-induced flaking, even under high-temperature conditions, by maintaining grease flowability and preventing hydrogen penetration.
Implementation Method 1
a thickener consisting of a diurea compound
Implementation Method 2
zinc or calcium sulfonate as the anti-flaking additive... to prevent hydrogen penetration into the inside of metals
Implementation Method 3
a combination of amine and phenol antioxidants... to extend the bearing lubrication life even at elevated temperatures
Implementation Method 4
A grease composition for rolling bearings... capable of extending the bearing lubrication life even at elevated temperatures
Data Source
Figure 1
AI summary
The invention provides a grease composition for rolling bearings of automotive electrical equipment or automotive auxiliaries, containing a base oil that includes as an essential component an alkyldiphenyl ether oil; a diurea thickener represented by formula (1); an anti-flaking additive including an organic sulfonate rust inhibitor and a load carrying additive; and an antioxidant. In the formula (1), R2 is a bivalent aromatic hydrocarbon group having 6 to 15 carbon atoms; and one of R1 or R3 represents cyclohexyl group and the other represents cyclohexyl group, an alkyl group having 8 to 22 carbon atoms or an aromatic hydrocarbon group having 6 to 12 carbon atoms.