Relief valve

Claim 1

AS A SUBCOMBINATION, A PILOT VALVE ADAPTED TO ADMIT AND RELEASE PRESSURE FLUID INTO A PRESSURE CHAMBER IN RESPONSE TO THE PRESSURE OF THE FLUID, COMPRISING, IN COMBINATION, A HOUSING HAVING A BORE, AN INLET PORT, AN EXHAUST PORT AND AN INTERMEDIATE PORT CONNECTING THE BORE WITH THE PRESSURE CHAMBER, AN INLET VALVE IN THE BORE BETWEEN THE INLET PORT AND THE INTERMEDIATE PORT TO CONTROL THE FLOW OF PRESSURE FLUID TO THE PRESSURE CHAMBER, AN EXHAUST VALVE LOCATED BETWEEN THE INTERMEDIATE PORT AND THE EXHAUST PORT TO CONTROL THE FLOW OF PRESSURE FLUID FROM THE PRESSURE CHAMBER, EACH VALVE HAVING A VALVE MEMBER AND A VALVE SEAT WITH THE INLET VALVE HAVING AN EFFECTIVE AREA EXPOSED TO PRESSURE FLUID LARGER THAN THE EXHAUST VALVE, SAID EXHAUST VALVE SEAT BEING A FLAT, RELATIVELY THIN, ANNULAR RING MADE OF ELASTOMER MATERIAL AND THE VALVE ELEMENT HAVING A FLANGE PORTION WITH SIDES CONVERGING TOWARD ITS END TO PROVIDE A SURFACE FOR ENGAGING THE FLAT SIDE OF THE SEAT, SAID SURFACE HAVING A RELATIVELY SMALL AREA AS COMPARED TO THE AREA OF THE FLAT SIDE OF THE SEAT AND HAVING A DIAMETER SUBSTANTIALLY LARGER THAN THE INSIDE DIAMETER OF THE SEAT TO ALLOW UPSTREAM PRESSURE TO ACT ON THE PORTION OF THE SEAT INSIDE THE FLANGE OF THE VALVE ELEMENT AND CAUSE IT TO FLOW AGAINST THE FLANGE AND INCREASE THE AREA OF THE SEAL BETWEEN THE SEAT AND THE FLANGE, STOP MEANS TO LIMIT THE DISTANCE THE VALVE ELEMENT OF THE EXHAUST VALVE CAN TRAVEL TOWARD THE EXHAUST VALVE SEAT, RESILIENT MEANS URGING THE EXHAUST VALVE CLOSED, AND MEANS INTERCONNECTING THE VALVE MEMBER OF BOTH VALVES TO PREVENT THE VALVES FROM BEING CLOSED SIMULTANEOUSLY.