Automatic control system for a piston operated valve

Claim 1

THE COMBINATION OF A FLUID PRESSURE OPERATED VALVE AND A CONTROL SYSTEM FOR CLOSING SAID VALVE IN RESPONSE TO A PRESSURE CHANGE ABOVE A PRESELECTED HIGH OR BELOW A PRESELECTED LOW IN A PIPELINE IN WHICH SAID VALVE IS INSERTED, SAID VALVE HAVING A PISTON AND ADAPTED TO BE CLOSED BY THE APPLICATION OF A PREDETERMINED FLUID PRESSURE TO A SELECTED FACE OF SAID PISTON PORTION, SAID CONTROL SYSTEM COMPRISING A FLUID PRESSURE ACCUMULATOR CONTINUOUSLY FED BY SAID PIPELING AND CONNECTED TO DELIVER THROUGH CONTROL VALVES AGAINST SAID SELECTED FACE SAID PREDETERMINED FLUID PRESSURE, AND TWO CONTROL VALVES CONNECTED IN PARALLEL HYDRAULIC CIRCUITRY BETWEEN SAID ACCUMULATOR AND SAID SELECTED FACE, EACH OF SAID CONTROL VALVES COMPRISING A HOUSING CONTAINING A PISTON, MEANS FOR BIASING SAID PISTON AGAINST PIPELINE PRESSURE, SAID HOUSING HAVING FIRST AND SECOND OPENINGS, SAID PISTON SLIDABLY ENGAGING THE INNER SURFACE OF SAID HOUSING AND ADAPTED TO BE MOVED THROUGH A RANGE OF POSITIONS RELATIVE TO SAID HOUSING, SAID PISTON HAVING A TRANSVERSE PASSAGE SO ARRANGED AND CONSTRUCTED AS TO BE IN SIMULATENOUS COMMUNICATION WITH BOTH OF SAID OPENINGS WHEN SAID PISTON IS IN AT LEAST ONE OF SAID POSITIONS, AND TO BE OUT OF COMMUNICATION WITH AT LEAST ONE OF SAID OPENINGS WHEN SAID PISTON IS IN ORDER OF SAID OPENMEANS CONNECTING SAID FIRST OPENING TO SAID ACCUMULATOR, MEANS CONNECTING SAID SECOND OPENING TO COMMUNICATE WITH SAID PRESELECTED FACE, EACH OF SAID CONTROL VALVES THERBY ADAPTED TO ASSUME AN OPEN POSITION IN WHICH SAID OPENINGS COMMUNICATE WITH EACH OTHER THROUGH SAID TRANSVERSE PASSAGE AND SAID ACCUMULATOR IS IN COMMUNICATION THROUGH SAID OPEN VALVE WITH SAID SELECTED FACE AND DELIVERS SAID PREDETERMINED FLUID PRESSURE AGAINST SAID FACE, EACH OF SAID VALVES ALSO HAVING A CLOSED POSITION IN WHICH SAID OPENINGS ARE SEALED FROM EACH OTHER BY SAID PISTON AND SAID ACCUMULATOR IS SEALED OFF FROM SAID SELECTED FACE, EACH OF SAID CONTROL VALVES HAVING AN ADDITIONAL CONNECTION OF SAID PIPELINE, SAID ADDITIONAL CONNECTION ADAPTED TO DELIVER FLUID PRESSURE AGAINST EACH OF SAID PISTONS TO OPPOSE SAID BIASING MEANS, THE BIASING MEANS IN ONE OF SAID CONTROL VALVES ADJUSTED SO THAT SAID ONE VALVE REMAINS IN ITS CLOSED POSITION WHEN THE PIPELINE PRESSURE IS BELOW SAID PRESELECTED HIGH AND MOVES, UNDER THE FORCE OF SAID FLUID PRESSURE OPPOSING SAID BIASING MEANS, TO ITS OPEN POSITION WHEN THE PIPELINE PRESSURE RISES ABOVE SAID PRESELECTED HIGH, THE BIASING MEANS IN THE OTHER OF SAID CONTROL VALVES ADJUSTED SO THAT THE OTHER VALVE REMAINS IN ITS CLOSED POSITION WHEN THE PIPELINE PRESSURE IS ABOVE SAID PRESELECTED LOW AND MOVES, UNDER THE FORCE OF SAID BIASING MEANS, TO ITS OPEN POSITION WHEN THE PIPELINE PRESSURE FALLS BELOW SAID PRESELECTED LOW.