HYDRAULIC CONTROL SYSTEM AND METHOD OF CONTINUOUSLY VARIABLE TRANSMISSION

摘要

A hydraulic control system of continuously variable transmission includes: a first sheave pressure regulating valve (17) that regulates a line pressure (Pl), which is used for hydraulic control as a source pressure, to obtain a first sheave pressure (Pin); a fail-safe valve (19) that selects and outputs any one of the first sheave pressure (Pin) or a fail-safe hydraulic pressure (second sheave pressure Pout) that is applied to a drive pulley (21) at the time of a failure due to an excessive first sheave pressure (Pin) to the drive pulley (21); and a first regulator valve (12) and a second regulator valve (13) that regulate the line pressure (Pl). An output pressure (Psf) of the fail-safe valve (19) is supplied to the first and second regulator valves (12 and 13) in a feedback manner as a drive pulley (21) side hydraulic pressure to thereby regulate the line pressure (Pl).