Gm Global Technolgoy Operations, Inc.

Brent D Calcut

Reuben Sarkar

Thomas J Chapaton

Marie-Christine G Jones

James L Linden

Antifoam compositions for functional fluids contain antifoam agents comprising perfluoropolyether compounds (PFPE). An automatic transmission fluid is provided containing the antifoam composition in a lubricating base oil, along with conventional additives such as antiwear agents. Automobile transmissions are provided that contain an automatic transmission fluid containing the new antifoam compositions. In a further embodiment, methods are provided for reducing foam in an engine oil or unwanted noise in an automobile transmission during operation, comprising lubricating the engine or transmission with a lubricating fluid containing the antifoam compositions of the invention.

Controlled release of perfluoropolyether antifoam additives from compounded rubber

Antifoam compositions for automatic transmission fluids contain antifoam agents comprising perfluoropolyether compounds (PFPE). An automatic transmission fluid is provided containing the antifoam composition in a lubricating base oil, along with conventional additives such as antiwear agents. Automobile transmissions are provided that contain an automatic transmission fluid containing the new antifoam compositions. In a further embodiment, methods are provided for reducing unwanted noise in an automobile transmission during operation, comprising lubricating the transmission with an ATF containing the antifoam compositions of the invention.

Thermally stable antifoam agent for use in automatic transmission fluids

A rubber composition contains an antifoam compound that leaches out of the rubber composition when placed in contact with a functional fluid. The antifoam compound is delivered into a functional fluid such as an automatic transmission fluid or an engine oil by contacting the functional fluid with the rubber composition. In addition to the antifoam compound, the rubber composition contains one or more elastomers, which may be selected from a wide variety of natural or synthetic rubbers. In a preferred embodiment, the elastomer comprises a high temperature elastomer such as acrylic elastomer and ethylene acrylic elastomer.

Controlled release of antifoam additives from compounded rubber

The remaining useful life of a transmission fluid in a vehicle is continually estimated by a transmission control computer module during vehicle operation using both an oxidation model and a shift energy model. The oxidation model uses experimentally determined remaining useful fluid life values obtained at temperatures experienced by the fluid in transmission usage and subtracts incremental values from said life based on the temperature-time experience of volume fractions of the fluid in the sump and torque converter. The shift energy model starts with an estimated maximum number of shifts and continually obtains a current remaining useful life by deducting for actual shifts and estimated shift energy inputs based on fluid temperature. Notice of end of fluid useful life is given when one of the models first determines no remaining useful fluid life.

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Allen Park, MI, United States of America

Brent D Calcut