Patent ID: 8843287

Claim:
A control device for a belt type continuously variable transmission, comprising a primary pulley for receiving an input from a drive source, a secondary pulley for providing an output to a drive wheel, and a belt wrapped around the primary pulley and the secondary pulley to control a belt clamp force on the basis of a command secondary hydraulic pressure to the secondary pulley, the device further comprising: a switch means configured to determine, on the basis of a belt slip control permitting condition, whether or not to permit a belt slip control in which the secondary hydraulic pressure is reduced from that in a normal control and to switch between the belt slip control and the normal control; and a control means configured to in the normal control, set the command secondary hydraulic pressure by a feedback control based on a deviation between a target secondary hydraulic pressure and an actual secondary hydraulic pressure to control the secondary hydraulic pressure to the secondary pulley, and in the belt slip control, inhibit the feedback control based on the deviation, and, in replace of the feedback control, control the secondary hydraulic pressure to the secondary pulley by oscillating the secondary hydraulic pressure and monitoring a phase difference between an oscillation component included in an actual hydraulic pressure and an oscillation component included in an actual gear ratio to estimate a belt slip condition, and setting the command secondary hydraulic pressure on the basis of an estimation of the belt slip condition so that a predetermined belt slip condition is maintained.