Continuously variable transmission with an electro-hydraulic control system and method for operating such transmission

摘要

Continuously variable transmission provided with a first pulley having two pulley discs, with a second pulley having two pulley discs and with a drive belt wound around the pulleys for transmitting torque therebetween, at least one disc of the first pulley being axially movable with respect to the other disc of the pulley under the influence of an axial force provided on the movable disc by a hydraulic pressure in a cylinder of a piston/cylinder assembly associated with the first pulley. The continuously variable transmission is further provided with a control system capable of controlling the pressure in the cylinder and including a pump for generating a flow of hydraulic medium from a reservoir to a main hydraulic line and a line pressure valve at least operable by a control pressure which is regulated by an electronically operable pressure regulator, for controlling a line pressure in the main hydraulic line. Additionally the control system includes a pressure control device capable of influencing the line pressure by providing a further pressure on a part of the line pressure valve.