Aromatic Imide Lubricant Additives for Transmission Shudder
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Solution Overview
Problem
Automatic transmission fluids face challenges in achieving a high static coefficient of friction and durable positive slope in the µ-V curve, which is essential for preventing transmission shudder, as traditional friction modifiers often result in low static friction and lack sufficient durability.
Innovation Solution
A lubricating composition comprising an oil of lubricating viscosity and a condensation product of pyromellitic anhydride with an aliphatic primary amine, specifically N,N-dialkyl-1,3-propanediamine, which forms an imide, is used to impart improved frictional properties and antiwear performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional friction modifiers are used in automatic transmission fluids, then the fluid can be formulated with conventional additives, but the static coefficient of friction becomes low and the positive slope durability is insufficient
Solution Approach 1:
The patent changes the chemical structure parameter of the friction modifier by using condensation products of hydroxy-polycarboxylic acids with N,N-di(hydrocarbyl) alkylenediamines to form amide or imide structures. This structural parameter change enables both high static coefficient of friction and durable positive slope characteristics, resolving the contradiction between reliability and friction force.
Solution Approach 2:
The patent employs composite chemical structures combining hydroxy-polycarboxylic acid moieties with N,N-di(hydrocarbyl) alkylenediamine moieties. This composite molecular architecture provides both the high static friction needed for clutch holding and the positive slope durability for anti-shudder performance, simultaneously addressing both requirements.
2Force
If friction modifiers are designed to increase static coefficient of friction, then clutch holding capacity improves, but the positive slope durability deteriorates
Solution Approach 1:
The patent modifies the chemical parameters of the friction modifier by incorporating specific hydroxy-polycarboxylic acid and N,N-di(hydrocarbyl) alkylenediamine structures. This parameter optimization enables the formulation to achieve both high clutch holding capacity through increased static friction and sustained positive slope durability over time.
Solution Approach 2:
The patent ensures continuous effective friction modification by designing additives that maintain stable film properties throughout the service lifetime. The condensation product structure provides continuous protective action, ensuring both clutch holding capacity and positive slope durability are maintained consistently over extended periods.
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 composition effectively maintains a high coefficient of friction and positive slope over extended periods, reducing the occurrence of transmission shudder and providing antiwear and corrosion inhibition, thus enhancing the longevity and performance of automatic transmissions.
Implementation Method 1
a condensation product of (i) pyromellitic anhydride with (ii) an aliphatic primary amine, containing 6 to 80 carbon atoms, wherein the aliphatic primary amine is an N,N-dialkyl-1,3-propanediamine, said condensation product comprising an imide
Data Source
Figure 1
AI summary
A composition useful as a lubricant for an automatic transmission comprises an oil of lubricating viscosity and a condensation product of an aromatic polycarboxylic acid or mixtures thereof or a reactive equivalent thereof, having at least two carboxylic groups situated so as to permit formation of a cyclic imide having 5 or 6 atoms in said cyclic structure; with an aliphatic primary amine or alcohol, containing 6 to 60 carbon atoms.