Controller and control method of belt type continuously variable transmission

A control method for a belt type continuously variable transmission by a belt slip control in which a belt slip condition among a primary pulley, a secondary pulley, and a belt is controlled with a hydraulic pressure, the method comprising:

• in the belt slip control, oscillating the hydraulic pressure to control the hydraulic pressure on the basis of a multiplied value of an oscillation component included in an actual hydraulic pressure and an oscillation component included in an actual gear ratio;
• and
• permitting the belt slip control when a change speed of the gear ratio of the belt type continuously variable transmission is less than a predetermined value at which the oscillation component due to oscillation included in the actual gear ratio is separable from a variation in the actual gear ratio.

A control method for a belt type continuously variable transmission by a belt slip control in which a belt slip condition among a primary pulley, a secondary pulley, and a belt is controlled with a hydraulic pressure, the method comprising:

• in the belt slip control, oscillating the hydraulic pressure to control the hydraulic pressure on the basis of a phase difference between an oscillation component included in an actual hydraulic pressure and an oscillation component included in an actual gear ratio;
• and
• permitting the belt slip control when a change speed of the gear ratio of the belt type continuously variable transmission is less than a predetermined value at which the oscillation component due to oscillation is extracted from a variation in the actual gear ratio.

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 so as to control a gear ratio determined by a running radius ratio of the belt on the pulleys by controlling a primary hydraulic pressure to the primary pulley and a secondary hydraulic pressure to the secondary pulley, the device further comprising:

• a belt slip controller configured to oscillate the secondary hydraulic pressure and monitor a phase difference between an oscillation component included in an actual secondary hydraulic pressure and an oscillation component included in an actual gear ratio to estimate a belt slip condition, and control the actual secondary hydraulic pressure to decrease on the basis of an estimation of the belt slip condition to maintain a predetermined belt slip condition;
• and
• a belt slip control permission determining unit configured to permit the belt slip controller to perform a belt slip control when a change speed of the gear ratio of the belt type continuously variable transmission is less than a predetermined value at which the oscillation component included in the actual gear ration and a variation in the actual gear ratio are separated from each other.