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An electronically controlled five-speed automatic transmission has been developed for use in new 2-liter models. This high-performance gearbox is the world's first five-speed automatic transmission for passenger car use to be equipped with a torque converter. It is designed with an ultra-wide range and close ratio gearing and incorporates a host of outstanding technologies to provide excellent performance and driveability. This paper describes the major features and performance of this new automatic transmission and some of the studies undertaken concerning multiplication of gear steps.

There has been a growing need to develop more compact automatic transmissions with a greater number of speeds for better fuel economy and better driveability. This study investigated a method for determining suitable planetary gear trains for today's transmissions. A computer program has been developed for application to five-speed transmissions consisting of two planetary gearsets. By analyzing various gear train possibilities, the program can identify which gearsets are suitable for different conditions, including the number of speeds, the number of binding elements, topological suitability and other factors.

The operating characteristics of the check valve in the clutch piston of an automatic transmission have a great effect on the shifting performance and durability of the developed clutch package test rig was used to visualize the flow and make pressure measurements in the vicinity of the check valve. The results indicate that the strength of the vortex just in front of the check valve strongly influences the opening and closing hydraulic pressure of the valve. It was also found that the vortex causes a pressure drop, which is related to the rotating speed of the clutch piston, oil volume discharged from the check valve and valve geometry. These results were used to design an improved check valve which provides a suitable oil pressure curve for achieving smoother shifting.

We succeeded in developing a parallel hybrid electric vehicle (HEV) with a fuel efficiency in the 10-15 mode more than double that of existing vehicles of the same class of driving performance. A prominent feature of this HEV system is the belt-drive continuously variable transmission (CVT) with built-in traction motor and powder clutch. Adopting a more efficient configuration proved effective in minimizing cost increases and loss of space utility and offered the same reliability provided by existing vehicles. This paper discusses the functional design aspects of the parallel HEV system, which holds great promise for viable mass production.

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.