Flapper type hydraulic servo valve for controlling fluid flow

Claim 1

FLOW CONTROL APPARATUS COMPRISING A PAIR OF FLAPPER VALVES EACH EMBODYING A CHAMBER WHICH INCLUDES A SUPPLY PORT, A DRAIN PORT AND A CONSTANTLY OPEN OUTLET PORT; A SUPPLY LINE CONNECTED TO THE SUPPLY PORT OF EACH VALVE; A DRAIN LINE CONNECTED TO THE DRAIN PORT OF EACH VALVE; ONE OUTLET LINE CONNECTED TO THE OUTLET PORT OF ONE VALVE AND ANOTHER OUTLET LINE CONNECTED TO THE OUTLET PORT OF THE OTHER VALVE; A CONTROL ELEMENT FOR EACH VALVE HAVING A FIRST POSITION IN WHICH THE SUPPLY PORT IS CLOSED BUT THE DRAIN PORT IS OPEN, AND HAVING A SECOND POSITION IN WHICH THE SUPPLY PORT IS OPEN BUT THE DRAIN PORT IS CLOSED; PRESSURE RESPONSIVE MEANS OPERATIVELY CONNECTED WITH SAID CONTROL ELEMENTS FOR REPETITIVELY ALTERNATING THE POSITIONS OF THE CONTROL ELEMENTS BETWEEN SAID FIRST AND SECOND POSITIONS AND DISPOSING THE CONTROL ELEMENT OF ONE VALVE IN ONE OF THE SAID FIRST AND SECOND POSITIONS WHENEVER THE CONTROL ELEMENT OF THE OTHER VALVE IS IN THE OTHER OF SAID POSITIONS; A CONTROL VALVE EMBODYING A CHAMBER WHICH INCLUDES A SUPPLY PORT CONNECTED WITH THE SAID SUPPLY LINE, A DRAIN PORT CONNECTED WITH THE SAID DRAIN LINE, AND A CONSTANTLY OPEN PORT; A LINE CONNECTED THE CONSTANTLY OPEN PORT OF SAID CONTROL VALVE WITH THE PRESSURE RESPONSIVE MEANS FOR SUPPLYING PRESSURIZED FLUID THERETO; A CONTROL MEMBER FOR THE SAID CONTROL VALVE MECHANICALLY CONNECTED TO THE PRESSURE RESPONSIVE MEANS FOR ACTUATION THEREBY, SAID CONTROL MEMBER HAVING ALTERNATE POSITIONS IN ONE OF WHICH THE SUPPLY PORT OF THE CONTROL VALVE IS OPEN BUT THE DRAIN PORT IS CLOSED AND IN THE OTHER OF WHICH THE SUPPLY PORT IS CLOSED BUT THE DRAIN PORT IS OPEN SUCH THAT THE PRESSURE RESPONSIVE MEANS IS ACTUATED TO MOVE THE CONTROL MEMBER WHEN IN ONE OF THE ALTERNATE POSITIONS TO THE OTHER POSITION.