Patent ID: 6409624
Filing Date: 2002-06-25
Classification: F16H

Abstract:
In an automatic transmission having a frictionally engaging element that is hydraulically actuated for assuming a plurality of gear positions,a hydraulic control system comprising: a first hydraulic section that produces a line pressure; a solenoid valve that produces a solenoid pressure upon receiving a solenoid signal; a first pressure control valve that produces a first output pressure from said line pressure by using said solenoid pressure and said first output pressure as operation signal pressures, said first output pressure having a smaller gain with respect to said solenoid pressure; a second pressure control valve that produces a second output pressure from said line pressure by using said solenoid pressure and said second output pressure as operation signal pressures, said second output pressure having a larger gain with respect to said solenoid pressure; and a switching valve that selectively assumes a first position to feed said engaging element with said first output pressure when the engagement of said engaging element brings about a higher gear position that needs a smaller torque contribution, and a second position to feed said engaging element with said second output pressure when the engagement of said engaging element brings about a lower gear position that needs a larger torque contribution.