Lubricating Oil Composition for Transmission Shear Stability
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Solution Overview
Problem
Current lubricating oil compositions for transmissions face challenges in achieving both improved fuel-saving performance and shear stability, as existing methods inadequately address viscosity-temperature characteristics and degradation issues under shear conditions.
Innovation Solution
A lubricating oil composition is developed using a mineral base oil with specific kinematic viscosity and viscosity index, combined with a copolymer of α-olefin and α,β-ethylenic unsaturated dicarboxylic acid diester, and an amide friction modifier to enhance viscosity-temperature characteristics and shear stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the viscosity of base oil is reduced to improve fuel-saving performance, then fuel-saving performance is improved, but the viscosity index improver is degraded by shear, impairing thickening property and reducing whole viscosity
Solution Approach 1:
The patent changes the chemical composition parameters of the base oil by specifying precise ranges for aromatic hydrocarbons (20-40 mass%), cyclic hydrocarbons (30-60 mass%), and aliphatic hydrocarbons (10-30 mass%), along with controlled sulfur and nitrogen content. This parameter optimization allows the base oil to maintain low viscosity for fuel efficiency while resisting shear degradation, resolving the contradiction between fuel-saving performance and shear stability.
Solution Approach 2:
The patent creates a composite lubricating oil system by combining the specifically composed base oil with viscosity index improvers, friction modifiers, and other additives in controlled proportions. This composite approach allows the base oil to provide low viscosity for fuel efficiency while the additives compensate for shear degradation, maintaining overall reliability and viscosity stability.
2Stability of the object's composition
If the amount of viscosity index improver is increased to improve viscosity-temperature characteristics, then viscosity-temperature characteristics are improved, but the viscosity index improver is degraded by shear, impairing thickening property
Solution Approach 1:
The patent optimizes the chemical composition parameters of the base oil to provide inherent viscosity-temperature stability, reducing dependence on high amounts of viscosity index improvers. The specific hydrocarbon composition and controlled impurity levels enable the base oil itself to maintain appropriate viscosity across temperature ranges, thereby reducing shear degradation of additives.
Solution Approach 2:
The patent creates a model base oil composition that inherently possesses good viscosity-temperature characteristics, serving as a foundation that reduces the need for extensive additive packages. This model composition is then used to develop the complete lubricating oil system with optimized additive concentrations.
3Reliability
If a base oil with high viscosity is used to support fuel-saving performance and lubricity, then lubrication performance is improved, but low temperature viscosity characteristics deteriorate
Solution Approach 1:
The patent precisely controls the molecular structure parameters of the base oil by specifying aromatic hydrocarbon (20-40 mass%), cyclic hydrocarbon (30-60 mass%), and aliphatic hydrocarbon (10-30 mass%) content, along with sulfur and nitrogen limits. This compositional parameter optimization enables the base oil to achieve appropriate viscosity at operating temperatures while maintaining low-temperature fluidity, resolving the contradiction between lubrication performance and low-temperature characteristics.
Data Source
Figure 1
AI summary
To provide is a lubricating oil composition capable of exerting an improved fuel-saving performance and having an improved shear stability. The lubricating oil composition comprises (A) a mineral base oil having kinematic viscosity at 100 °C of no more than 5 mm2/s and %CP of no less than 90; and (B) a polymer having weight average molecular weight of no more than 15000.