Patent ID: 7192371
Filing Date: 2007-03-20
Classification: F16H,Y10T

Abstract:
1. A system for controlling a V-belt type continuously variable transmission (CVT) for a vehicle with an engine, comprising: primary and secondary pulleys arranged on input and output sides, the pulleys having V-grooves, the pulleys having primary-pulley and secondary-pulley chambers defined at least by movable flanges, the primary-pulley and secondary-pulley chambers being subjected to primary-pulley and secondary-pulley pressures produced from a line pressure; a V-belt looped over the primary and secondary pulleys to engage in the V-grooves; a shift control valve arranged to move in such a manner to vary the primary-pulley pressure and to vary a width of the V-groove of the primary-pulley; a shift link that mechanically links the movable flange of the primary pulley and the shift control valve; return springs arranged in the primary-pulley and secondary-pulley chambers, respectively, in such a manner to bring the primary and secondary pulleys into a predetermined shift ratio during tractive cruising of the vehicle; a shift actuator mechanically linked with the shift link and arranged to move so as to vary a relationship between position of the shift control valve and position of the movable flange of the primary pulley; and an electronic control unit (ECU) which controls the shift actuator in such a manner to conform a shift ratio obtained from a rotational-speed ratio between the primary and secondary pulleys to a target shift ratio, the ECU being so programmed as to: