| 摘要 |
<p>System and method for controlling a continuously variable transmission having a pair of variable-diameter pulleys disposed on input and output shafts, and a corresponding pair of hydraulic cylinders to change effective diameters of the pulleys. A speed ratio control valve assembly is used to control flows of a fluid to and from one of the cylinders. The control valve assembly is selectively placed in one of three states consisting of a first state for feeding the fluid to the one cylinder, a second state for discharging the fluid from the one cylinder, and a third state for restricting the flow to or from the one cylinder. The first and third states are alternately established while a ratio of an operating time in the first state to that in the third state is changed, for controlling a rate of flow of the fluid into the one cylinder, and the second and third states are alternately established while a ratio of operating time in the second state to that in the third state is changed, for controlling a rate of flow of the fluid from the one cylinder, whereby the speed ratio of the transmission is continuously varied by the one cylinder under control of the speed-ratio control valve assembly.</p> |
