Hydraulic control system for automatic transmissions

Abstract

Abstract A HYDRAULIC CONTROL SYSTEM FOR AUTOMATIC TRANSMISSIONS IS APPLIED TO A MULTISTAGE CHANGE GEAR MECHANISM INCLUDING HYDRAULICALLY ACTUATED FRICTION ELEMENTS INCLUDING CLUTCHES AND BRAKES, SELECTIVELY COOPERABLE WITH COMPONENTS OF THE MECHANISM TO ESTABLISH THE INPUT-OUTPUT GEAR RATIO, AND INCLUDES AN ACCUMULATOR WHICH LESSENS THE SHOCK, RESULTING FROM THE PRESSURE CHANGES DURING SHIFTING, BY CONTROLLING THE TRANSIENT PRESSURE CHANGE OF THE HYDRAULIC FLUID SUPPLIED TO HYDRAULIC SERVOS ACTUATING THE FRICTION ELEMENTS. SHIFT VALVES, OPERABLE IN ACCORDANCE WITH ENGINE OUTPUT AND VEHICLE SPEED, CONTROL THE SUPPLY AND EXHAUST OF HYDRAULIC FLUID RELATIVE TO THE SERVOS. A RECIPROCABLE PISTON DIVIDES THE ACCUMULATOR INTO FIRST AND SECOND CHAMBERS, WITH THE FIRST CHAMBER CONTROLLING THE PRESSURE CHANGE TO THE HYDRAULIC SERVOS DURING SHIFTING AND THE SECOND CHAMBER CONTROLLING OPERATION OF THE ACCUMULATOR. A RETURN VALVE EXHAUSTS THE SECOND CHAMBER OF THE ACCUMULATOR IN CONNECTION WITH OPERATION OF THE SHIFT VALVE UPON SHIFTING. THE ACCUMULATOR PISTON RETURNS TO ITS INITIAL POSITION AFTER COMPLETION OF SHIFTING. D R A W I N G

Inventors

• 👤 F Ushijima

Bibliographic Details