Fluid biased flow control means

Claim 1

IN A FLUID FLOW CONTROL VALVE HAVING AN OUTLET OPENING COMPRISING A VALVE SEAT AND A CLOSURE MEMBER FOR SELECTIVELY OPENING AND CLOSING THE OUTLET OPENING, IN COMBINATION THEREWITH THE IMPROVEMENT COMPRISING MEANS FOR MOVING SAID CLOSURE MEMBER ALONG AN AXIS NORMAL TO THE OUTLET OPENING, SAID MEANS COMPRISING A CYLINDER, SAID CLOSURE MEMBER COMPRISING A PISTON HAVING ONE END SLIDABLY MOUNTED IN SAID CYLINDER AND HAVING SEALING MEANS AT ITS OPPOSITE END ADAPTED TO ENGAGE AND SEAL SAID OUTLET OPENING, DETENT MEANS CARRIED BY SAID CYLINDER LIMITING THE TRAVEL OF SAID PISTON OUT OF SAID CYLINDER BY ENGAGING A PORTION OF SAID PISTON SO THAT THE PISTON HAS A PRESELECTED STROKE WITHIN SAID CYLINDER, MEANS DEFINING AN OPENING THROUGH SAID PISTON SO THAT THE FLUID PRESSURE EXERTED ON THE PISTON FACE WITHIN SAID CYLINDER CORRESPONDS TO THE PRESSURE EXERTED ON THE SEALING END OF THE PISTON, SAID PISTON FACE HAVING A GREATER AREA THAN THE AREA DEFINED BY SAID OUTLET OPENING SO THAT THE SEALING MEANS IS RETAINED IN ITS CLOSED POSITION BY THE FORCE EXERTED ON THE PISTON FACE, SO THAT THE OUTLET OPENING WILL REMAIN CLOSED AS THE CYLINDER MOVES ALONG A PATH SUBSTANTIALLY EQUAL IN LENGTH TO THE STROKE OF THE PISTON AND SO THAT THE SEALING MEANS MAY BE MOVED TO AN OPEN POSITION WHEN SAID DETENT MEANS ENGAGES SAID PORTION OF THE PISTON.