Automatic Transmission Fluid Friction Stability
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Solution Overview
Problem
Existing automatic transmission fluids face challenges in achieving high static coefficients of friction while maintaining durable positive slope characteristics during oxidative and mechanical stressing, which is often incompatible with traditional friction modifier technologies.
Innovation Solution
A lubricating composition comprising a major amount of oil of lubricating viscosity, 0.05 to 10 percent by weight of a condensation product of a secondary amine with two alkyl groups of at least 6 carbon atoms and a hydroxyacid or hydroxythioacid, 0.1 to 10 percent by weight of a nitrogen-containing dispersant, and a phosphorus-containing compound, with less than 0.1 percent by weight of zinc dialkyldithiophosphate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional friction modifier technology is used, then the fluid provides lubrication, but the static coefficient of friction is low and positive slope characteristics are not durable
Solution Approach 1:
The patent changes the chemical parameters of the friction modifier by using condensation products of hydroxy acids or hydroxy thioacids with diamines instead of traditional friction modifiers. This parameter change results in both high static coefficient of friction and durable positive slope characteristics during oxidative and mechanical aging
Solution Approach 2:
The invention employs composite friction modifier systems combining specific ratios of hydroxy acid/thioacid condensation products with diamines. This composite approach creates a synergistic effect that simultaneously achieves high static friction and durable positive slope characteristics, resolving the incompatibility between these two requirements
2Force
If friction modifiers are added to increase static friction, then clutch holding capacity improves, but friction stability deteriorates under oxidative and mechanical stress
Solution Approach 1:
The patent modifies the chemical structure parameters of the friction modifier by selecting specific hydroxy acids/thioacids and diamines with particular properties. These parameter changes ensure the friction modifier maintains both high clutch holding capacity and friction stability under oxidative and mechanical stress conditions
Solution Approach 2:
The invention uses readily available hydroxy acids, thioacids, and diamines that can be easily synthesized or obtained, replacing complex and expensive traditional friction modifiers. These simpler compounds provide comparable or superior performance with better stability characteristics
Data Source
AI summary
Compositions comprising an oil of lubricating viscosity; an amide represented by the formula R1R2N-C(O)R3 wherein R1 and R2 are hydrocarbyl groups of at least 6 carbon atoms and R3 is a hydroxyalkyl group of 1 to 6 carbon atoms or a group formed by the condensation of said hydroxyalkyl group, through a hy- droxyl group thereof, with an acylating agent; a nitrogen-containing dispersant; and a phosphorus-containing compound are suitable for lubricating a transmis- sion.