Patent ID: 6287227
Filing Date: 2001-09-11
Classification: F16H

Abstract:
A control for a continuously variable transmission having a drive sheave, a driven sheave, a flexible transmitter trained about the sheaves, and a selectively pressurizable control piston for each sheave for enforcing adjustment of the sheaves to control the speed ratio therebetween, said control comprising:first and second fluid passage means for communicating fluid to and from the drive sheave and the driven sheave, respectively;a source of primary pressure comprising a variable displacement pump communicating with said fluid passage means for pressurizing at least one of said passage means and the sheave communicating therewith at a pressure level determined by the torque requirement of the continuously variable transmission;check valve means in each of said passage means downstream of said source of primary pressure to inhibit fluid flow from said first and second passage means to said source of primary pressure;ratio control pressure source means comprising a variable displacement fluid pump for communicating fluid between said first and second passage means downstream of said check valve means for increasing a pressure level in one of said passage means to adjust the speed ratio between the sheaves; andelectro-hydraulic control means for controlling the pressure level of said source of primary pressure and for initiating and controlling the speed ratio between the sheaves.