Straddle flapper controlled hydraulic valve

Claim 1

IN A HIGH PRESSURE TWO-STAGE HYDRAULIC VALVE A VALVE SLEEVE MEMBER PROVIDED WITH INLET AND OUTLET PORTS FOR CONVEYING A HIGH PRESSURE FLUID SUPPLIED FROM AN EXTERNAL FLUID SUPPLY SOURCE; A VALVE SPOOL MEMBER AXIALLY SLIDABLE IN THE SLEEVE AND PROVIDED WITH EXTERNAL LAND AREAS MATING WITH THE PORTS IN THE SLEEVE FOR REGULATING THE SIZE OF THE OPENING OF THE INLET AND OUTLET PORTS IN COMMUNICATION WITH EACH OTHER IN ACCORDANCE WITH ITS AXIAL POSITION, SAID SPOOL MEMBER HAVING A PAIR OF UNCONNECTED OPENINGS INTERNALLY THEREOF, EACH COMMUNICATING WITH A DIFFERENT OPPOSITE END OF THE SPOOL AND LEADING TO A SMALL METERING ORIFICE NEAR THE CENTER OF THE SPOOL, SAID METERING ORIFICES OPENING ON OPPOSITE SIDES OF THE SPOOL, THE SLEEVE HAVING A CYLINDRICAL REGION AT EACH END OF THE SPOOL; MEANS SUPPLYING FLUID UNDER PRESSURE FROM THE EXTERNAL FLUID SUPPLY SOURCE TO THE CYLINDRICAL REGIONS AT SAID ENDS OF THE SPOOL; AND, A FIRST STAGE MOVABLE FLAPPER MEMBER HAVING A PAIR OF LEGS STRADDLING THE SPOOL TO NORMALLY SEAL SAID METERING ORIFICES WHEN THE SPOOL IS AXIALLY CENTERED WITHIN THE SLEEVE, SAID FIRST STAGE FLAPPER MEMBER BEING REVERSIBLY DISPLACEABLE RELATIVE TO THE SPOOL MEMBER IN RESPONSE TO A COMMAND SIGNAL TO THEREBY SELECTIVELY OPEN THE METERING ORIFICES, THE FLUID PRESSURE IN THE CYLINDRICAL REGIONS AT BOTH ENDS OF THE SPOOL BEING SUBSTANTIALLY EQUALIZED WHEN THE FLAPPER MEMBER SEALS BOTH METERING OPENINGS, THE FLUID PRESSURE IN THE CYLINDRICAL REGION AT ONE END OF THE SPOOL BEING REDUCED RELATIVE TO THAT IN THE CYLINDRICAL REGION AT THE OPPOSITE END THEREOF WHEN THE METERING OPENING IN COMMUNICATION WITH THE CYLINDRICAL REGION AT SAID ONE END IS UNCOVERED BY THE FLAPPER MEMBER, THEREBY CAUSING SAID SPOOL TO BE AXIALLY DISPLACED IN THE DIRECTION OF THE REDUCED PRESSURE CYLINDRICAL REGION AT SAID ONE END OF THE SPOOL UNTIL THE METERING ORIFICIES ARE AGAIN SEALED BY THE LEGS OF THE FLAPPER MEMBER.