Patent ID: 8062156
Filing Date: 2011-11-22
Classification: F16H

Abstract:
1. A control device for a continuously variable transmission having a variable speed pulley including first and second variable speed pressure chambers that control the groove width of the pulley, a tightening pulley including a tightening pressure chamber that controls the groove width of the pulley, and a power transmission element wound around the variable speed pulley and the tightening pulley, the control device comprising: a line pressure control valve provided between a hydraulic pressure supply source and the tightening pulley to regulate hydraulic fluid supplied from the hydraulic pressure supply source to have a pressure of a line pressure, the hydraulic fluid being supplied to the first variable speed pressure chamber and the tightening pressure chamber; a speed ratio control valve provided between the line pressure control valve and the variable speed pulley to regulate hydraulic fluid supplied from the line pressure control valve to have a pressure of variable speed control pressure, the hydraulic fluid being supplied to the second variable speed pressure chamber; a first reducing valve provided between the line pressure control valve and the variable speed pulley, the first reducing valve passing the hydraulic fluid regulated by the line pressure control valve toward the variable speed pulley and, when the line pressure exceeds a first limit pressure, reducing the pressure of the hydraulic fluid and supplying the hydraulic fluid with the reduced pressure to the variable speed pulley; and a second reducing valve provided between the speed ratio control valve and the variable speed pulley, the second reducing valve passing the hydraulic fluid regulated by the speed ratio control valve toward the variable speed pulley and, when the variable speed control pressure exceeds a second limit pressure, reducing the pressure of the hydraulic fluid and supplying the hydraulic fluid with the reduced pressure to the variable speed pulley.