Patent ID: 6306061
Filing Date: 2001-10-23
Classification: F16H,Y10T

Abstract:
A hydraulic control system for a continuously variable transmission mounted on a motor vehicle having an engine, a torque converter connected with said engine via a lockup clutch for transmitting torque to said transmission, a hydraulic pressure source driven by said engine for generating a hydraulic pressure, a forward and reverse changeover apparatus including a forward clutch and a reverse brake, actuators for actuating said forward clutch and said reverse brake, and an input and an output shaft, said transmission including a primary pulley provided on said input shaft, a secondary pulley provided on said output shaft and a drive belt wound around said primary and secondary pulleys, comprising:a secondary pressure control valve for regulating said hydraulic pressure to a secondary pressure for actuating said secondary pulley;a clutch pressure control valve for regulating said secondary pressure to a clutch pressure lower than said secondary pressure and for supplying said clutch pressure at least to either of said lockup clutch and said actuators;a lubrication pressure line for supplying a lubrication pressure discharged from said secondary pressure control valve;a release chamber provided in said lockup clutch;a release pressure line connected with said release chamber;an oil cooler for cooling hydraulic fluid of said torque converter;a cooler line connected to said oil cooler;an apply chamber provided in said lock-up clutch;an apply pressure line connected with said apply chamber;a clutch pressure line for supplying said clutch pressure;a slip pressure control valve for reducing said clutch pressure and generating a slip pressure;a slip pressure line for supplying said slip pressure; anda switching valve switchable betweena position where said lubrication pressure line communicates with said release pressure line and simultaneously said cooler line communicates with said apply pressure line and simultaneously said slip pressure line communicates with said changeover pressure line, anda position where said clutch pressure line communicates with said apply pressure line and simultaneously said slip pressure line communicates with said release pressure line, and simultaneously said lubrication pressure line communicates with said cooler line and simultaneously said clutch pressure line communicates with said changeover pressure line.