Automotive Automatic Transmissions Research Articles

ELECTRO-HYDRAULIC TWO STAGE PROPORTIONAL PRESSURE CONTROL VALVE

Automotive automatic power transmissions have some pressure control valves which control the pressure of wet-clutches or band- brakes. Recent transmissions have replaced hydro-mechanical valves with electro-hydraulic valves for the improvement of shift quality of gear changes. A conventional proportional pressure control valve is controlled by asolenoid with a triangular leakage path of magnetic flux which causes lower reproducibility and productibity. And it is difficult for a single stage valve to control high flow rates. Here, we have designed a new type of proportional solenoid with a rectangular leakage path in magnetic circuit with an aid of FEM analysis, and controlled a secondary valve by a primary valve with a spool of 2 mm in diameter. The dynamics of the valve and the presssure control system are simulated by bond graphs which manipulate nonlinear elements symbolically.