Toyota has developed a new continuously variable transmission (CVT) called "Direct Shift-CVT" which is for 2.0-liter class vehicles. This CVT provided not only power transmission by a metal belt held with a conventional pulley but also additional gear mechanism. This CVT is developed to improve fuel efficiency, acceleration characteristic, and quietness.
At this CVT, the startup low gear ratio is achieved by gear mechanism and the power is switched by clutches. Since the belt-pulley portion can be realized to be wide range by using only high gear ratio range, the input load into belt-pulley portion is reduced and unprecedented compact and high efficient belt-pulley portion is established. Consequently, the high efficiency in all fields from startup acceleration to high speed driving is achieved to improve fuel efficiency. In order to achieve emotional driving performance, driving force is optimized by switching the gears and the belt-pulley portion based on the operation of drivers and driving scenes. Moreover, a new control technology improves shift response in sequential shiftmatic mode.
This paper describes details about new control technology applied to the Direct Shift-CVT, and some concrete examples of improvements of vehicle characteristics.