Patent ID: 7402118

Claim:
A control device for controlling a continuously variable transmission, the continuously variable transmission having a primary pulley with a permitted rotation speed region and a secondary pulley with a V-belt looped around the primary and secondary pulleys, the control device comprising: an oil pressure control unit which supplies an oil pressure to the primary pulley and secondary pulley based on a command signal indicative of a target speed-reduction ratio, a sensor which detects a rotation speed of the primary pulley, and a controller which transmits the command signal indicative of the target speed-reduction ratio to the oil pressure control unit, the controller being programmed to: set the target speed-reduction ratio to a first speed-reduction ratio; calculate a first predetermined rotation speed of the primary pulley at which the V-belt reaches a first limiting temperature at the first speed-reduction ratio; compare the detected rotation speed of the primary pulley with the first predetermined rotation speed; calculate a first elapsed time after the detected rotation speed of the primary pulley exceeds the first predetermined rotation speed; maintain the first speed-reduction ratio when the first elapsed time is equal to or less than a first predetermined time; and set the target speed-reduction ratio to a second speed-reduction ratio smaller than the first speed-reduction ratio when the first elapsed time exceeds the first predetermined time; wherein, at the second speed-reduction ratio, the temperature of the V-belt should become equal to or less than the first limiting temperature throughout the permitted rotation speed region of the primary pulley.