| 摘要 |
PURPOSE: A control device of a belt type continuously variable transmission is provided to prevent slip of the belt by securing hydraulic pressure sufficiently without lowering fuel efficiency in switching from the travel range into the engine brake range. CONSTITUTION: A hydraulic control unit(100) comprises a pressure regulating valve(60) regulating line pressure discharged from an oil pump(22), a transmission control valve(30) regulating primary hydraulic pressure of a primary pulley cylinder chamber(10c), and a pressure reducing valve(61) regulating secondary pressure to a secondary pulley cylinder chamber(11c). The speed ratio of a primary pulley and a secondary pulley is controlled by a stepping motor(40), and a spool(31) is operated according to displacement of a servo link(50). A CVTCU(continuously variable transmission control unit,20) is composed of a transmission control unit(201) deciding the desired speed ratio according to vehicle speed or stroke of an accelerator pedal and controlling the actual speed ratio by driving the stepping motor, and a pulley pressure control unit(202) regulating friction between the primary pulley and the secondary pulley according to input torque, speed ratio, oil temperature and shifting rate. The delay time is set for increasing hydraulic pressure based on engine rpm and oil temperature in deciding switch shifting, and the desired speed ratio is maintained before changing the range signal during the predetermined delay time. |
