Patent ID: 6739994
Filing Date: 2004-05-25
Classification: F16H

Abstract:
A continuously variable transmission, comprising:a first pair of conical disks including an axially moveable disk and an axially non-movable disk whereby a running radius of the first pair of disks is changeable; a second pair of conical disks including an axially movable disk and an axially non-movable disk whereby a running radius of the second pair of disks is changeable; an endless transmission element arranged to couple the first pair of disks with the second pair of disks; a first hydraulic actuator in operative connection with the movable disk of the first pair of disks for axially moving the disk, the first actuator having an inlet port; a second hydraulic actuator in operative connection with the movable disk of the second pair of disks for axially moving the disk, the second actuator having an inlet port; a first, four-quadrant controllable independent pump-motor combination having a first port connected to the inlet port of the first actuator, and a second port connected to the inlet port of the second actuator, the first pump-motor combination being operative to control a fluid flow between the inlet ports of the actuators; a second, two-quadrant controllable independent pump-motor combination having an inlet port connected to a hydraulic medium source, and an outlet port connected to the inlet port of one of the actuators, the second pump-motor combination being operative to control tension in the endless transmission element; means for controlling and varying output of the second pump-motor combination in dependence on a required operating tension in the endless transmission element; and means for controlling and varying a quantity and direction of fluid flow through the first controllable independent pump-motor combination respectively to and from the first and second actuators in dependence on a required change in the respective running radii of the pairs of disks controlled thereby, both the first and second pumps being driven discontinuously.