Eccentric plug valve having antislamming means

Claim 1

IN AN ECCENTRIC PLUG TYPE VALVE, THE COMBINATION COMPRISING A VALVE BODY HAVING WALLS DEFINING A CIRCULAR ENTRANCE, A PLUG INSERTED INTO SAID ENTRANCE AND ROTATABLE ABOUT THE AXIS THEREOF BETWEEN OPEN AND CLOSED POSITONS, SAID VALVE BODY HAVING A FLUID FLOW PASSAGE THERETHROUGH OPENED AND CLOSED BY AN ECCENTRIC PORTION OF SAID PLUG WHEN THE LATTER IS ROTATED BETWEEN ITS TWO POSITIONS, THE ECCENTRIC PORTION OF SAID PLUG WHEN PARTIALLY OPEN HAVING A FORCE EXERTED THEREON BY PASSING FLUID WHICH TENDS TO SLAM IT TO ONE OF SAID POSITIONS, SAID PLUG HAVING A CYLINDRICAL PORTION DISPOSED IN SAID ENTRANCE, FIRST AND SECOND ANNULAR GROOVES DEFINED IN THE WALL OF SAID ENTRANCE, A RESILIENT DEFORMABLE RING DISPOSED IN SAID FIRST GROOVE AND DEFORMED INTO SEALING ENGAGEMENT WITH SAID CIRCULAR PORTION, A BRAKING RING OF FRICTION MATERIAL OVERLYING A RADIAL END SURFACE ON SAID CYLINDRICAL PORTION, A RADIALLY COMPRESSIBLE RETAINER RING HELD CAPTIVE IN SAID SECOND GROOVE AND EXTENDING THEREFROM TO OVERLIE SAID BRAKING RING, AND MEANS ON SAID PLUG CAUSING FLUID PRESSURE IN SAID VALVE BODY TO URGE IT OUTWARDLY OF SAID ENTRANCE SO THAT SAID BRAKING RING IS COMPRESSED BETWEEN SAID PLUG AND RETAINING RING TO CREATE A RETARDING FORCE ON SAID PLUG WHICH PREVENTS SLAMMING OF THE LATTER.