Variable positive displacement pump with rising pressure curve

Claim 1

IN A VARIABLE DISPLACEMENT PUMP HAVING (A) A PUMP ROTOR AND A VARIABLE DISPLACEMENT ELEMENT, SUCH AS A SLIDING RING, MOVABLE WITH RESPECT TO THE ROTOR TO VARY THE DISPLACEMENT OF THE PUMP BY VARYING THE ECCENTRICALLY OF THE DISPLACEMENT ELEMENT RELATIVE TO THE AXIS OF ROTATION OF THE ROTOR, AND (B) CONTROL MEANS FOR NORMALLY POSITIONING THE DISPLACEMENT ELEMENT IN ECCENTRIC POSITION AND FOR DECREASING THE ECCENTRICALLY OF SAID DISPLACEMENT ELEMENT IN RESPONSE TO PRESSURE DEVELOPED BY THE PUMP, (C) SAID CONTROL MEANS INCLUDING PRESSURE-RESPONSIVE MEANS AND AN OPPOSED RESILIENT ELEMENT WHICH IS STRESSED BY THE PRESSURE-RESPONSIVE MEANS IN RESPONSE TO PRESSURE DEVELOPED BY THE PUMP, AND THE REACTION FORCE OF WHICH RESILIENT ELEMENT DETERMINES THE PRESSURE REQUIRED TO BE DEVELOPED BY THE PUMP TO PRODUCE MOVEMENT OF THE DISPLACEMENT ELEMENT IN A DISPLACEMENT-REDUCING DIRECTION, THE IMPROVEMENT WHICH COMPRISES THE COMBINATION THEREWITH OF (D) MEANS RESPONSIVE TO FLOW OF PUMPED LIQUID AND OPERATIVE, IN RESPONSE TO INCREASED FLOW, TO AUGMENT THE FORCE EXERTED BY SAID RESILIENT ELEMENT IN OPPOSITION TO THE PRESSURE-RESPONSIVE MEANS, WHEREBY, IN RESPONSE TO FLOW, THE PRESSURE REQUIRED TO BE DEVELOPED BY THE PUMP TO CAUSE DISPLACEMENT-REDUCING MOVEMENT OF THE DISPLACEMENT ELEMENT IS INCREASED BEYOND THAT DETERMINED BY THE RESILIENT ELEMENT.