Well tools

Claim 1

A WELL FLOW CONTROL DEVICE INCLUDING: AN OUTER TUBULAR MEMBER; A VALVE MEMBER MOVABLY MOUNTED IN THE SAID TUBULAR MEMBER FOR LONGITUDINAL MOVEMENT THEREIN AND HAVING A LONGITUDINAL FLOW PASSAGE FORMED THEREIN; MEANS SEALING BETWEEN SAID TUBULAR OUTER MEMBER AND SAID VALVE MEMBER, SAID FLOW PASSAGE OF SAID VALVE MEMBER COMMUNICATING WITH THE INTERIOR OF THE TUBULAR OUTER MEMBER ABOVE AND BELOW SAID SEAL MEANS; MEANS ON SAID OUTER TUBULAR MEMBER BELOW SAID SEAL MEANS AND ON SAID VALVE MEMBER BELOW SAID FLOW PASSAGE ENGAGEABLE UPON MOVEMENT OF SAID VALVE MEMBER LONGITUDINALLY OF SAID OUTER MEMBER TO CLOSE OFF FLOW OF FLUIDS THROUGH SAID VALVE MEMBER; BIASING MEANS IN SAID OUTER MEMBER ENGAGING SAID VALVE MEMBER AND BIASING SAID VALVE MEMBER TOWARD SUCH CLOSED POSITION, SAID VALVE MEMBER HAVING AN AREA THEREON EXPOSED TO THE PRESSURE OF FLUIDS FLOWING THROUGH SAID VALVE MEMBER, SAID PRESSURE OF FLUIDS FLOWING THROUGH SAID VALVE MEMBER ACTING ON SAID AREA OF SAID VALVE MEMBER AGAINST SAID FORCE EXERTED BY SAID BIASING MEANS TO MOVE SAID VALVE MEMBER LONGITUDINALLY IN SAID OUTER MEMBER TO A POSITION OPENING SAID PASSAGE OF SAID VALVE MEMBER TO PERMIT FLOW THERETHROUGH, SAID AREA OF SAID VALVE MEMBER BEING DOWNSTREAM OF THE VALVE MEANS WHEREBY WHEN SAID VALVE MEMBER IS IN CLOSED POSITION, PRESSURE OF FLUIDS UPSTREAM OF SAID VALVE ACTING ON SAID VALVE MEMBER COACTS WITH SAID BIASING MEANS TO HOLD SAID VALVE MEMBER IN CLOSED POSITION.