Controlling apparatus

Claim 1

A FLUID CONTROL DEVICE, COMPRISING TWO PNEUMATIC RELAYS, A WALL PORTION FORMING A SEPARATE CHAMBER FOR EACH RELAY, A PAIR OF SPACED-APART APERTURES FORMED IN THE WALL PORTION OF EACH RELAY TO RESPECTIVELY FORM A FLUID INLET AND EXHAUST PORT FOR EACH OF THE CHAMBERS, A PAIR OF FLEXIBLE MEMBERS POSITIONED IN EACH CHAMBER FORMING OPPOSING WALL PORTIONS THEREOF, A CONNECTING ROD EXTENDING THROUGH AND IN FLUID-TIGHT ENGAGEMENT WITH EACH OF THE FLEXIBLE MEMBERS, A THIRD CHAMBER FORMED BY A STATIONARY WALL PORTION AND ONE OF THE FLEXIBLE MEMBERS, AN INLET PASSAGEWAY FORMED IN THE STATIONARY WALL PORTION OF SAID THIRD CHAMBER FOR APPLYING A FLUID PRESSURE REPRESENTATIVE OF THE MAGNITUDE OF A CONDITION THERETO, A SEPARATE FLAPPER POSITIONED TO SUBSTANTIALLY COVER EACH PORT, A SEPARATE SPRING FOR ONE END OF EACH FLAPPER POSITIONED TO NORMALLY RETAIN EACH FLAPPER IN SUBSTANTIALLY FLUID-TIGHT ENGAGEMENT WITH AN INNER WALL SURFACE OF THE CHAMBER FORMING THE END OF ITS ASSOCIATED PORT, THE OTHER END OF THE FLAPPER COVERING THE EXHAUST PORT IN ONE OF THE RELAYS BEING OPERABLY CONNECTED FOR MOVEMENT WITH THE CONNECTING ROD TO OPEN THE LAST-MENTIONED PORT WHILE THE FLAPPER CONVERING THE INLET PORT IN THE SECOND OF THE FIRST TWO MENTIONED RELAYS IS SIMULTANEOUSLY OPENED UPON THE OCCURRENCE OF AN INCREASE IN THE MAGNITUDE OF THEFLUID IN THE THIRD CHAMBER FROM A PRESELECTED LEVEL, THE OTHER END OF THE FLAPPER CONVERING THE INLET PORT IN SAID ONE OF THE RELAYS BEING OPERABLY CONNECTED FOR MOVEMENT WITH THE CONNECTING ROD TO OPEN THE LAST-MENTIONED PORT WHILE THE FLAPPER CONVERING THE OUTLET PORT IN THE SECOND ONE OF THE AFOREMENTIONED RELAYS IS SIMULTANEOUSLY CLOSED UPON THE OCCURRENCE OF A DECREASE IN THE MAGNITUDE OF THE FLUID IN SAID THIRD CHAMBER FROM THE PRESELECTED LEVEL, A CYLINDER, FIRST AND SCOND INLETS ADJACENT OPPOSITE ENDS OF THE CYLINDER, A PISTON SLIDABLY DIPOSED WITHIN THE CYLINDER, A PASSAGEWAY CONNECTING THE FLUID UNDER PRESSURE IN SAID FIRST CHAMBER BY WAY OF THE FIRST INLET WITH AN INNER PORTION OF THE CYLINDER THAT IS AT ONE END OF THE PISTON, ANOTHER PASSAGEWAY CONNECTING THE FLUID UNDER PRESSURE IN THE SECOND CHAMBER BY WAY OF THE SECOND INLET WITH AN INNER PORTION OF THE CYLINDER THAT IS AT THE OTHER END OF THE PISTON, THE PISTON ROD BEING CONNECTED FOR MOVEMENT WITH THE PISTON, AND A FEEDBACK SPRING AD LINKAGE INTERCONNECTING THE PISTON ROD WITH THE CONNECTING ROD TO APPLY A NEGATIVE FEEDBACK FORCE TO SAID CONNECTING ROD.