Urea-Thickened Grease Composition for Torque and Leak Control
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Solution Overview
Problem
Greases used in speed reducers and speed increasers face challenges in balancing torque transmission efficiency with leak prevention performance, often resulting in abrasion and seizure due to reduced grease supply and high load conditions.
Innovation Solution
A grease composition with a urea-based thickener having a controlled particle size of 2.0 μm or less and specific surface area of 0.5×105 cm2/cm3 or more, combined with a base oil and extreme pressure agents, to enhance both torque transmission and leak prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the worked penetration of grease is increased to improve torque transmission efficiency, then the torque transmission efficiency is improved, but the leak prevention performance of the grease lowers
Solution Approach 1:
The invention changes the particle size parameter of the thickener from conventional larger sizes to specifically 10 μm or less (preferably 5 μm or less, more preferably 3 μm or less). This parameter change allows the grease to achieve both soft consistency for good torque transmission and fine particle distribution for excellent leak prevention, resolving the contradiction between these two performance requirements.
Solution Approach 2:
The invention uses a composite thickener system comprising urea-based thickener and metal soap thickener in specific proportions (urea-based: 5-50 mass%, metal soap: 50-95 mass%). This composite approach combines the advantages of both thickeners - urea-based provides fine particle size and good leak prevention, while metal soap provides structural stability and torque transmission, thus resolving the contradiction between leak prevention and torque transmission efficiency.
2Strength
If the proportion of thickener and additives in grease is increased to improve load bearing performance, then the load bearing performance is improved, but grease leak occurs more frequently
Solution Approach 1:
The invention optimizes the particle size parameter of the thickener to 10 μm or less, which allows achieving high load bearing performance through increased thickener proportion while maintaining excellent leak prevention. The fine particle size ensures proper grease consistency and retention even with higher thickener content, resolving the contradiction between load bearing and leak prevention.
Solution Approach 2:
The composite thickener system with specific composition ratios enables the grease to withstand high loads while preventing leaks. The metal soap component provides structural strength for load bearing, while the urea-based component with fine particles ensures leak prevention, thus resolving the contradiction when increasing overall thickener proportion.
3Productivity
If a soft grease with increased worked penetration is used to improve torque transmission, then the torque transmission efficiency is improved, but the supply amount of grease gradually reduces causing abrasion and seizure
Solution Approach 1:
The invention changes the particle size parameter to 10 μm or less, which creates a unique grease structure that maintains soft consistency for excellent torque transmission while having improved grease retention and supply characteristics. This prevents the gradual reduction of grease supply that leads to wear, thus resolving the contradiction between torque transmission and wear resistance.
Solution Approach 2:
The composite thickener system provides both the softness needed for torque transmission and the structural stability needed for grease retention. This ensures continuous grease supply to prevent abrasion and seizure while maintaining high torque transmission efficiency, resolving the contradiction between these two requirements.
Data Source
AI summary
A grease composition may be used for speed reducers and speed increasers, being excellent in both torque transmission efficiency and leak prevention performance. The grease composition may contain a base oil (A) and a urea-based thickener (B), which is used for speed reducers and speed increasers, wherein the particles containing the urea-based thickener (B) in the grease composition satisfy the following requirement (I). Requirement (I): the area-based arithmetic average particle diameter of the particles is 2.0 μm or less, as measured by a laser diffraction/scattering method.