Low Viscosity Automatic Transmission Fluids with Enhanced Friction Durability

This study focused on the development of a new low viscosity automatic transmission fluid(ATF) with enhanced friction durability to meet the needs of new step type automatic transmissions.Recent high fuel prices encourage increased efficiency in the driveline,including the transmission.Reduction in fluid viscosity and wider use of slip control in torque converter clutches are two ways to practically improve fuel efficiency.Increased torque and more shifting is seen with a variety of new transmission hardware platforms,such as wet starting clutches,dual clutches and seven-or eight-speed ATs.This suggests the need for enhanced levels of friction durability from the ATF.The new challenge from this hardware for the ATF formulator lies in the need to simultaneously meet the wear,friction durability and torque capacity requirements at low viscosity in a cost-effective manner.This report introduced a new low viscosity fluid that represents a different commercial ATF formulation style.The new chemistry employs a low viscosity for increased fuel economy,while easily doubling the friction durability of current conventional ATFs and offering higher torque and better EP.