Fluid pressure control

Abstract

Abstract A PRESSURE CONTROL FOR A FLUID DEVICE SUCH AS A VARIABLEDELIVERY PUMP. A SERVO VALVE HAS AN ELONGATE OPENING IN WHICH A CONTROL PISTON IS LONGITUDINALLY SLIDABLE ABOUT AN EQULIBRIUM POSITION WHERE THE FORCES OF AN ADJUSTABLE COMPRESSION SPRING AND OF THE PUMP DISCHARGE PRESSURE ON A SMALL SURFACE AT THE RIGHT END ARE BALANCED BY TGE DISCHARGE PRESSURE ON A LARGER SURFACE AT THE LEFT END. INCREASED DISCHARGE PRESSURE MOVES THE CONTROL PISTON TO THE RIGHT, APPLYING THE INCREASED PRESSURE TO THE FLEXIBLE CAM RING OF THE PUMP SO AS TO REDUCE ITS ECCENTRICITY AND THE DISCHARGE RATE. DECREASED DISCHARGE PRESSURE ALLOWS THE CONTROL PISTON TO MOVE TO THE LEFT, RELIEVING PRESSURE ON THE CAM RING TO INCREASE ITS ECCENTRICITY AND THE DISCHARGE RATE. OSCILLATION OF THE CONTROL PISTON DURING CHANGES IN THE DISCHARGE RATE ARE SUBSTANTIALLY ELIMINATED BY A DAMPING PISTON HAVING A CONSTRICTED LONGITUDINALLY PASSAGE THROUGH IT AND POSITIONED TO THE LEFT OF THE CONTROL PISTON BETWEEN COMPRESSION SPRINGS. THE SPACE TO THE LEFT OF THE DAMPING PISTON COMMINICATES WITH A FLUID PRESSURE THAT IS RESPONSIVE TO THE ECCENTRICITY OF THE CAM RING. AS THE CONTROL PISTON MOVES ONE WAY IN RESPONSE TO A CHANGE IN DISCHARGE PRESSURE THE DAMPING PISTON MOVES IN THE OPPOSITE DIRECTION, THEREBY ANTICIPATIRULY DECELERATING AND MINIMIZING OVERSHOOT BY THE CONTROL PISTON, WHICH THEN RETURNS TO THE EQUILIBRIUM POSITION AS THE DAMPING PISTON MOVES OPPOSITELY TO ITS EQUILIBRIUM POSITION AND THUS ANTICIPATORILY DECELERATE AND MINIMIZES OSCILLATION BY THE CONTROL PISTON.

Inventors

• 👤 Robert K Mitchell

Bibliographic Details