Fluid pressure actuated flow control gate valve

Claim 1

A FLOW CONTROL VALVE FOR CONTROLLING FLOW OF FLUID THERETHROUGH COMPRISING: A VALVE HOUSING, SAID HOUSING HAVING A TOP, A BASE END ENCLOSING A COMPARTMENT, SAID HOUSING HAVING ALIGNED INLET AND OUTLET PORTS IN COMMUNICATION WITH SAID COMPARTMENT; A SEATING SURFACE SURROUNDING SAID INLET PORT; A GATE DISPOSED WITHIN SAID COMPARTMENT FOR MOVEMENT IN A PATH NORMAL TO SAID PORTS, SAID GATE HAVING A CYLINDRICAL CHAMBER OPENING THROUGH ONE SIDE THEREOF, THE AXIS OF SAID CYLINDRICAL CHAMBER BEING PARALLEL TO THE AXIS OF SAID ALIGNED PORTS; A PASSAGEWAY PASSING THROUGH SAID GATE PROVIDING FLUID COMMUNICATION BETWEEN SAID COMPARTMENT AND SAID CHAMBER; MEANS FOR SEALING SAID PASSAGEWAY; A LATERALLY MOVABLE PISTON DISPOSED IN SAID CYLINDRICAL CHAMBER HAVING AN INNER AND OUTER FACE; AN ANNULAR SEALING PROJECTION FORMED INTEGRALLY ON THE OUTER FACE OF SAID PISTION; MEANS COMMUNICATING WITHS AID INLET PORT AND SAID CYLINDRICAL CHAMBER FOR PASSING SAID FLUID TO AID INNER FACE OF SAID PISTON PROVIDING FOR THE ESTABLISHMENT OF A PRESSURE DIFFERENTIAL ACROSS SAID PISTON, SAID PRESSURE DIFFERENTIAL ACTING TO SEALABLY SEAT SAID PISTON AGAINST SAID SEATING SURFACE; RESILIENT MEANS ACTING IN OPPOSITION TO SAID PRESSURE DIFFERENTIAL TO RETAIN SAID PISTON IN SAID CYLINDRICAL CHAMBER; A FLEXIBLE SEAL MEANS DISPOSED BETWEEN SAID PISTON AND SAID CHAMBER PROVIDING FOR A FLUID TIGHT SEAL THEREBETWEEN; MEANS CONNECTED TO SAID GATE FOR ALIGNING SAID PISTON MEANS CARRIED BY SAID GATE FOR ALLOWING GENERALLY FRICTION-FREE MOTION OF SAID VALVE GATE RELATIVE TO SAID HOUSING.