Development of New-Generation Belt CVTs With High Torque Capacity for Front-Drive Cars 2003-01-0593
Work has been proceeding on the development of new-generation continuously variable transmissions (CVTs) since 1997. At that time JATCO introduced the world's first torque converter-type belt CVT designed for 2.0-liter class engines and incorporating electronic shift control. This new generation includes three belt CVTs, ranging in torque capacity from 100 to 350 Nm. The CVT3 described in this paper has the largest torque capacity of the three, handling torque levels up to a maximum of 350 Nm.
These new-generation CVTs are premised on use in global markets and have been developed with the aim of achieving a more compact design, lighter weight and a wider ratio range, among other objectives. Their product appeal has been substantially enhanced based on previous experience acquired in developing a 2.0-2.5liters class CVT. To improve the product appeal of these new-generation CVTs, a super ultra-flat torque converter was developed along with reducing the diameter of the primary pulley. In this connection, a new pulley pressure control system was developed, the pressure control valve was reduced in size and pressure control accuracy was enhanced, among other improvements.
This paper describes the major specifications of the CVT3, powertrain construction, pressure control system and experimental data. The data were measured with a test vehicle incorporating this CVT, which show its effect on improving fuel economy and power performance.