CONTROL DEVICE OF BELT TYPE CONTINUOUSLY VARIABLE TRANSMISSION WITH TORQUE CONVERTER FOR INCREASING FUEL EFFICIENCY BY RESTRICTING OVER LINE PRESSURE AND IMPROVING DURABILITY OF BELT

摘要

PURPOSE: A control device of a belt type continuously variable transmission is provided to increase the fuel efficiency by restricting over line pressure in increasing the speed ratio, and to improve the durability of the belt by restricting slip of the belt. CONSTITUTION: A control device of a belt type continuously variable transmission(5) is composed of a primary pulley(10) and a secondary pulley(11) connected to an engine(1) through a torque converter(2) to support a V-belt(12); a transmission control valve changing the speed ratio by regulating hydraulic pressure of the primary pulley; a speed ratio control unit controlling the transmission control valve to reach the desired speed ratio; an input torque estimating unit estimating input torque to the primary pulley based on the speed ratio and the torque ratio of the torque converter; and a line pressure control unit regulating line pressure to the transmission control valve and the secondary pulley based on the estimated input torque and the desired speed ratio. The input torque estimating unit comprises a speed ratio increase or decrease detecting unit sensing increase or decrease of the speed ratio, and a torque ratio setting unit setting the torque ratio in increasing the speed ratio less than the torque ratio in decreasing the speed ratio.