Patent ID: 6219608
Filing Date: 2001-04-17
Classification: F16H,Y10T

Abstract:
An electronic transmission control system for an automotive vehicle with a belt-type continuously variable automatic transmission employing a primary pulley with a primary pulley actuation chamber, a secondary pulley with a secondary pulley actuation chamber, and a drive belt running in the primary and secondary pulleys whose effective diameters are continuously variable to provide varying pulley ratios, comprising:a transmission ratio control device including:(a) a first motor-driven oil pump which supplies working pressure directly to one of the primary and secondary pulley actuation chambers;(b) a second motor-driven oil pump which supplies working pressure directly to the other of the primary and secondary pulley actuation chambers, and enables working oil to come and go between the primary and secondary pulley actuation chambers therethrough;(c) a first control section which controls said first motor-driven oil pump with feed-forward compensation for the working pressure supplied to the one of the primary and secondary pulley actuation chambers, based on changes in a flow rate of the working oil coming and going between the primary and secondary pulley actuation chambers through said second motor-driven oil pump, so that the working pressure supplied to the one of the primary and secondary pulley actuation chambers is regulated as a belt capacity holding pressure needed to hold a belt capacity of the drive belt in a first motor-driven pump side, said belt capacity of the drive belt in the first motor-driven pump side being defined as a capacity required for exerting a grip of the drive belt in a pulley side having the one of the primary and secondary pulley actuation chambers; and(d) a second control section which controls said second motor-driven oil pump, so that the working pressure supplied to the other of the primary and secondary pulley actuation chambers is regulated as a belt capacity holding pressure needed to hold a belt capacity of the drive belt in a second motor-driven pump side and so that a required value of a speed-change flow rate of the working oil coming and going between the primary and secondary pulley actuation chambers through said second motor-driven oil pump is obtained, said speed-change flow rate being defined as a required flow rate needed for speed-change control action, and said belt capacity of the drive belt in the second motor-driven pump side being defined as a capacity required for exerting a grip of the drive belt in a pulley side having the other of the primary and secondary pulley actuation chambers.