METHOD FOR CONTROLLING SPEED CHANGE FOR CONTINUOUSLY VARIABLE TRANSMISSION

摘要

PURPOSE:To reduce shock due to speed change by performing the speed change when throttle opening is changed to a smaller side in the case where a driving frequency of a hydraulic pressure control valve for controlling hydraulic pressure in a hydraulic control valve means for speed change ration is changed from a high side to a low side. CONSTITUTION:This continuously variable transmission 2 is provided with a driving pulley 6 and a driven pulley 12 whose effective diameters are adjustable, and the speed change ration is changed by shifting movable pulley pieces 10 and 16 in their axial directions by inletting and outletting hydraulic oil to and from a hydraulic chambers 24 and 26. A primary pressure control valve (hydraulic pressure control valve for the transmission) 44 is arranged in an oil driving passage 38 in a hydraulic chamber 24 side, and the hydraulic pressure regulated by a three-way electromagnetic valve (hydraulic pressure control valve for operation) 52 is introduced to the valve 44. This three-way electromagnetic valve 52 is driven at the driving frequency to be regulated by a control means, and when this driving frequency is switched from a high side to a low side, shock due to the speed change is suppressed by performing the switching at the time when the throttle opening is changed to a smaller side.