Speed ratio control method and device for continuously variable transmission

摘要

(Object) To improve the drivability by controlling a target engine speed according to an engine load and a vehicle running condition to ensure an actual engine speed. (Constitution) In controlling a speed ratio of a continuously variable transmission, an adaptation factor A as an element for deciding a target engine speed is computed according to constants a and b, an average engine load theta ths, and an average vehicle speed change quantity DELTA Vs, i.e., by the expression of A = a theta ths + b DELTA Vs. Even when the average engine load theta ths changes because of fluctuation in an accelerator opening, various running modes can be decided by the adaptation factor A depending upon both the average engine load theta ths and the average vehicle speed change quantity DELTA Vs, thereby eliminating a feeling of discomfort upon changing a speed in the continuously variable transmission.