Vehicle automatic transmission system hydraulic pressure control mechanism has two systems to determine gear selection and third to correct engagement pressure

摘要

The hydraulic pressure control mechanism for a change to a higher gear in a motor vehicle automatic transmission system with a series of hydraulic friction clutches has a first system (102) to determine whether the upward gear change command has been started while there is no pressure on the accelerator pedal, a second system (104) to determine whether a factor modifying an automatic transmission input torque has been generated, and a correction command system to correct the engagement pressure of the predetermined hydraulic friction clutch in conformity with the modification factor. The mechanism also has a computer (106) to calculate the gear selection value on the basis of the vehicle's actual speed, and a system to determine a differential value between the rotational speed of the transmission input shaft and synchronised speed.