Method of controlling rotational speed of continuous variable transmission

Claim 1

In a method of controlling rotational speed of a continuously variable transmission in which each of a driving side pulley and a driven side pulley has a fixed pulley member and a movable pulley member which is supported relative to the fixed pulley member so that it can move toward and away from the fixed pulley member, and in which the driving side pulley is drivingly connected to an engine, including the steps of decreasing and increasing groove width between each pair of said fixed and movable pulley member to cause a rotational radius of a belt reeved between both of said pulleys to be respectively increased and decreased and thereby change the belt ratio of the transmission, the improvement comprising the steps of providing a hydraulic clutch which engages and disengages the transmission in response to a clutch pressure applied thereto to connect with and disconnect from a driving force which is output from the continuously variable transmission, providing a control section for (1) calculating an objective clutch pressure of the hydraulic clutch from (a) an engine torque value which is determined by a throttle opening degree and (b) an objective engine rotational speed, and (2) controlling actual clutch pressure in each of various selectable clutch control modes so as to correspond to the objective clutch pressure, and selectively using said control section to correct the objective engine rotational speed based on transmission oil temperature when the selected clutch control mode is a normal vehicle motion starting mode.