Method and apparatus for controlling continuously variable transmission for vehicle

摘要

Method and apparatus for controlling a continuously variable transmission operatively connecting an engine and drive wheels of a vehicle, wherein a speed ratio of the transmission is controlled such that an actual engine speed coincides with a target engine speed. The method and apparatus comprise steps or devices for: determining a normal target speed based on a currently required output of the engine; determining a rate of variation in the speed ratio of the transmission; determining a transmission efficiency of the transmission based on the determined rate of variation in the speed ratio; determining a variation-restraint trigger speed based on the determined transmission efficiency and on the determined normal target speed, the trigger speed being lower than the normal target speed; restraining the rate of variation in the speed ratio while the actual engine speed is raised from the trigger speed to the normal target speed during acceleration of the vehicle; and selecting the trigger speed as a special target speed when the actual engine speed has been raised to the normal target speed. After the special target speed has been selected, the transmission is controlled such that the engine speed is lowered to the special target speed, i.e., to the variation-restraint trigger speed.