Lubricating Oil Composition for CVT Anti-Shudder and Friction
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Solution Overview
Problem
Conventional lubricating oil compositions for continuously variable transmissions face a trade-off between anti-shudder life and metal-to-metal friction coefficient, where lowering viscosity to improve fuel efficiency reduces the friction coefficient, and existing solutions fail to maintain sufficient torque transmission and anti-shudder performance.
Innovation Solution
A lubricating oil composition combining boronated succinimide compounds with specific weight-average molecular weights, along with a polymethacrylate viscosity index improver and an ether sulfolane compound, to enhance anti-shudder life and shear stability without lowering the metal-to-metal friction coefficient, while maintaining viscosity index and ensuring sealing rubber swellability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the viscosity of lubricating oil composition is lowered to improve fuel efficiency, then fuel consumption is reduced, but the metal-to-metal friction coefficient decreases, leading to insufficient torque transmission
Solution Approach 1:
The patent changes the chemical composition parameters of the lubricating oil by incorporating specific additives (succinimide compound, phosphorus compound, and friction modifier) in optimized ratios. This allows the oil to maintain sufficient friction coefficient for torque transmission while operating at lower viscosities for improved fuel efficiency.
Solution Approach 2:
The patent creates a composite lubricating oil formulation by combining multiple additive packages (succinimide compound, phosphorus compound, and friction modifier) with the base oil. This composite approach enables the oil to simultaneously achieve low viscosity for fuel efficiency and sufficient friction coefficient for torque transmission through synergistic effects of the additives.
2Duration of action of moving object
If the amount of friction modifier is increased to extend anti-shudder life of the lockup clutch, then anti-shudder performance is improved, but the metal-to-metal friction coefficient between metal belt and pulleys decreases, reducing torque transmission capability
Solution Approach 1:
The patent optimizes the concentration parameters of multiple additives simultaneously. By carefully controlling the amounts of succinimide compound, phosphorus compound, and friction modifier within specific ranges, the formulation achieves both extended anti-shudder life and maintained friction coefficient, resolving the trade-off between these two performance parameters.
Solution Approach 2:
The patent employs a composite additive package where succinimide compound, phosphorus compound, and friction modifier work synergistically. The succinimide and phosphorus compounds provide anti-shudder protection for the lockup clutch, while the friction modifier maintains adequate friction for torque transmission, achieving both goals simultaneously through the composite formulation.
Data Source
AI summary
Provided is a lubricating oil composition, which has low viscosity but also prolonged anti-shudder life without reduction of intermetallic friction coefficient. The lubricating oil composition is characterized in comprising (A) a lubricating base oil, and (C) (C-1) a borated succinimide compound with a mass average molecular weight of 4,000-7,000 and (C-2) a borated succinimide compound with a mass average molecular weight of greater than 7,000-10,000.