Craig D. Tipton

Toroidal CVTs: Rationalizing the fluid performance requirements

Global demands for fuel economy and reduced emissions have forced the automobile manufacturers to make significant changes over the last few decades. This has resulted in major improvements in engine designs and control systems, vehicle aerodynamics, tire design and fuel quality. In order to meet stringent government regulations and demands for better driveability, improvements have been made in the drive train components of the vehicles as well. Toroidal-CVT (t-CVT) has recently been introduced as an alternative automatic transmission technology. Traction fluid is a key component of a t-CVT, since it is responsible for power transmission in this type of transmission. Additional performance requirements which must be addressed in the formulation of practical automotive traction fluids include: low temperature viscometric, volatility, flash point, oxidation stability, elastomer compatibility shear stability, clutch friction performacne, and antiwear protection. In this work the extent of compromise among desirable characteristics in optimizing an automotive traction fluid for widespread use will be examined.