BELT BASED CONTINUOUSLY VARIABLE TRANSMISSION CONTROL DEVICE AND CONTROL METHOD

摘要

Provided is control device and method for a belt type continuously variable transmission which can reduce drive energy consumption by a decrease in belt friction when the estimated accuracy of belt slip condition is high and which can prevent the belt from greatly slipping during belt slip control when the estimated accuracy of belt slip condition is low. The device includes a primary pulley (42), a secondary pulley (43), and a belt (44) and controls gear ratio based on the running radius of the belt (44) on the pulley by controlling the primary oil pressure and the secondary oil pressure. A belt type continuously variable transmission (4) comprises a belt slip control means ( FIG. 8 ) for performing such control so as to oscillate the secondary oil pressure, estimate the belt slip condition by monitoring the phase difference between an oscillation component included in the actual secondary oil pressure and an oscillation component included in the actual gear ratio, and then reduce the actual secondary oil pressure to maintain a predetermined belt slip condition based on the estimation, and an oscillation setting means (sine wave oscillator 93a) for setting an oscillation amplitude of the secondary hydraulic pressure small when the gear ratio is a high gear ratio compared with when the gear ratio is a low gear ratio in a case of oscillating the secondary hydraulic pressure in the belt slip control.