Abstract
At the end of 1997, Toyota has launched a hybrid passenger car "PRIUS" based on new hybrid concept in Japan.
This system includes a drivetrain which features a planetary gear mechanism as a power split devices to divide the engine's power plus a generator and a motor.
This system functions as an electronically controlled continuously variable driving power transmission and combines power from the gasoline engine and electric motor. Energy storage device is newly developed high-output Ni-MH batteries which storage capacity is optimized to minimum to achieve outstanding fuel economy and performance. Computer control is used to optimize engine fuel consumption, minimize exhaust emissions, stop and start the engine and apply regenerative braking. As for the engine, we developed a new 1.5-liter gasoline engine that achieves high combustion efficiency through the application of the high expansion ratio Atkinson cycle. This vehicles fitted with this new hybrid system realized approximately twice the fuel economy of the conventional model and showed a high potential in terms of minimizing exhaust emissions.