Patent ID: 6259983
Filing Date: 2001-07-10
Classification: F16H,Y10T

Abstract:
A hydraulic control system for use in an automatic transmission to control a shift to a predetermined gear ratio by engaging a first frictional engagement element and disengaging a second frictional engagement element in accordance with a shift control routine for shift control of an engagement side pressure and a disengagement side pressure, wherein the automatic transmission includes: an input shaft which receives torque from an engine; an output shaft which is connected to vehicle wheels; and a plurality of frictional engagement elements for selectively changing a torque transmission path between the input shaft and the output shaft, including the first frictional engagement element and the second frictional engagement element;wherein said hydraulic control system comprises:a plurality of hydraulic servos for engaging and disengaging the frictional engagement elements in accordance with the engagement side and disengagement side pressures;a rotation change start detector which detects a start of change in rotational speed of the input shaft during the shift control;a rotation change rate detector which detects rate of change in the rotational speed of the input shaft at the detected start of the rotational speed change during the shift control;a learning controller which corrects the shift control based on a determination of time between start of execution of the shift control routine and the start of rotational speed change detected by the rotation change start detector and on the rate of change in the rotational speed of the input shaft detected by the rotation change rate detector; andan adjusting device for adjusting at least an engagement side pressure applied to the hydraulic servo for the first frictional engagement element, responsive to a predetermined signal from the learning controller.