Gas lift valve

Claim 1

A WELL TOOL INCLUDING: A HOUSING HAVING A FLOW PASSAGE AND A LATERAL APERTURE INTERMEDIATE THE ENDS OF SAID HOUSING COMMUNICATING SAID FLOW PASSAGE WITH THE EXTERIOR OF THE HOUSING; A VALVE MEANS COMPRISING AN ELONGATE BODY LONGITUDINALLY SLIDABLE IN SAID HOUSING, SAID HOUSING HAVING A VALVE SEAT ENGAGEABLE BY SAID ELONGATE BODY WHEN SAID ELONGATE BODY IS MOVED IN ONE DIRECTION TO ONE EXTREME LONGITUDINAL POSITION IN SAID HOUSING; SEALING MEANS BETWEEN SAID ELONGATE BODY AND SAID HOUSING, SAID LATERAL APERTURE BEING DISPOSED BETWEEN SAID VALVE SEAT AND SAID SEALING MEANS, SAID ELONGATE BODY CLOSING SAID FLOW PASSAGE TO PREVENT FLOW OF FLUIDS FROM SAID APERTURE TO SAID FLOW PASSAGE WHEN SAID ELONGATE BODY IS IN SAID ONE EXTREME LONGITUDINAL POSITION; AND MEANS RESPONSIVE TO FLUID PRESSURE COMPRISING A BELLOWS HAVING ONE END CONNECTED TO SAID ELONGATE BODY AND ANOTHER END CONNECTED TO SAID HOUSING TO FORM A CHAMBER IN SAID HOUSING BETWEEN SAID HOUSING AND SAID BELLOWS; SAID ELONGATE BODY HAVING A LONGITUDINALLY EXTENDING INTERNAL FLOW PASSAGE FORMED THEREIN COMMUNICATING AT ONE END WITH THE FLOW PASSAGE OF THE HOUSING AND EXTENDING LONGITUDINALLY OF SAID ELONGATE BODY PAST SAID SEALING MEANS TO THE EXTERIOR OF SAID ELONGATE BODY AT A POINT COMMUNICATING WITH SAID CHAMBER IN THE HOUSING TO CONDUCT FLUID PRESSURE FROM THE FLOW PASSAGE OF SAID HOUSING TO SAID MEANS RESPONSIVE TO FLUID PRESSURE FOR ACTUATING SAID ELONGATE BODY; SAID ELONGATE BODY AND SAID HOUSING HAVING COENGAGEABLE MEANS FOR CLOSING SAID CHAMBER FROM SAID PASSAGEWAY OF SAID ELONGATE BODY WHEN SAID ELONGATE BODY MOVES TO OPEN POSITION, SAID ELONGATE BODY AND SAID VALVE SEAT PROVIDING AN ANNULAR FLOW PASSAGE THEREBETWEEN SMALLER IN AREA THAN THE AREA OF THE LATERAL APERTURE OF THE HOUSING CONTROLLING FLOW FROM SAID LATERAL APERTURE THROUGH SAID SEAT TO THE FLOW PASSAGE OF THE HOUSING, WHEREBY THE ELONGATE BODY OF THE VALVE MEANS IS MOVABLE IN RESPONSE TO FLUID PRESSURE OF THE FLUID IN THE FLOW PASSAGE OF THE HOUSING.