Fluid pressure responsive seal assembly

Claim 1

IN COMBINATION: (A) COAXIAL, RELATIVELY AXIALLY MOVABLE, INNER AND OUTER MEMBERS RESPECTIVELY HAVING CYLINDRICAL INNER AND OUTER SURFACES; (B) SAID CYLINDRICAL SURFACES CONFRONTING EACH OTHER AND ONE OF THEM BEING PROVIDED WITH AN OPENING THEREIN; (C) THE OTHER OF SAID CYLINDRICAL SURFACES BEING PROVIDED THEREIN WITH AN ANNULAR GROOVE COAXIAL WITH SAID MEMBERS AND CONFRONTING SAID ONE CYLINDRICAL SURFACE; (D) SAID GROOVE HAVING A PERIPHERAL WALL AND HAVING ANNULAR END WALLS CONVERGING TOWARD SAID ONE CYLINDRICAL SURFACE AND MAKING ACUTE ANGLES WITH A PLANE PERPENDICULAR TO THE AXIS OF SAID MEMBERS; (E) AN O-RING IN SAID GROOVE AND ENGAGEABLE WITH SAID PERIPHERAL WALL OF SAID GROOVE AND SAID ONE CYLINDRICAL SURFACE; AND (F) MEANS, INCLUDING TWO DEFORMABLE AND AXIALLY MOVABLE BACK-UP RINGS DISPOSED IN SAID GROOVE BETWEEN SAID O-RING AND SAID END WALLS OF SAID GROOVE, RESPECTIVELY AND SQUEEZING SAID O-RING THEREBETWEEN IN RESPONSE TO A PRESSURE DIFFERENTIAL ACROSS SAID O-RING AND IN RESPONSE TO RELATIVE AXIAL MOVEMENT OF SAID MEMBERS, FOR CAMMING SAID O-RING AWAY FROM SAID ONE CYLINDRICAL SURFACE TO CLEAR SAID OPENING THEREIN.