Patent ID: 6122583
Filing Date: 2000-09-19
Classification: F16H,Y10T

Abstract:
A shift control valve system for a multiple ratio automatic transmission forming plural torque flow paths from an engine to a torque output shaft;planetary gear elements including a sun gear, a ring ear and a planetary carrier assembly defining said torque flow paths;a high ratio clutch means for connecting together two of said gear elements for rotation in unison, thereby establishing a high ratio;an underdrive brake means for anchoring one of said gear elements thereby establishing an underdrive ratio;said clutch means including a high ratio clutch servo having a clutch apply pressure chamber;said underdrive brake means including an underdrive brake servo having a brake apply pressure chamber and a brake release pressure chamber;said control valve system having a control pressure pump drivably connected to said engine, a first solenoid operated valve means for controlling pressure in said brake apply pressure chamber, and a second solenoid operated valve means for controlling pressure in said brake release pressure chamber and in said clutch apply pressure chamber whereby improved ratio shift quality is effected;said underdrive brake servo comprising a brake actuating piston defining in part said brake apply and brake release pressure chambers on opposite sides thereof as said brake actuating piston is stroked;said first solenoid operated valve means effecting a variable underdrive brake servo apply force on said brake actuating piston and said second solenoid operated valve means effecting a variable underdrive brake servo release force on said brake actuating piston whereby said first and second solenoid operated valve means allow clutch means capacity control by achieving variable stroke times independent of the stroke distance of said servo to improve ratio upshift quality.