Auxiliary, external, pressure seal for shank of plug valve

Claim 1

A ROTARY PLUG VALVE ASSEMBLY, COMPRISING A VALVE BODY, A COVER PLATE SECURED THEREON, A ROTARY PLUG IN THE BODY HAVING A TOP END, A SHANK EXTENDING FROM SAID TOP END THROUGH AN APERTURE IN SAID PLATE, SAID PLUG TOP END HAVING A FLAT SURFACE WHICH EXTENDS RADIALLY FORM AND MERGES WITH THE LOWER END OF THE SHANK BY A TRANSITION FILLET, AN ANNULAR DIAPHRAGM SEAL ASSEMBLY COMPRISING AT LEAST TWO DIAPHRAGM DISC IN SUPERIMPOSED RELATION, THE UPPERMOST DISC BEING OF METAL AND THE UNDERLYING ONE BEING NONMETALLIC, SAID ASSEMBLY ENCIRCLING SAID SHANK AND RESTING ADJACENT TO ITS CENTER UPON SAID FLAT SURFACE OF THE PLUG AND BEARING SNUGLY AT ITS INNER EDGE IN SAID FILLET, SAID DIAPHRAGM SEAL ASSEMBLY BEING PERIPHERALLY SECURED BETWEEN THE BODY AND THE COVER PLATE, A RIGID ANNULAR COLLAR ENCIRCLING THE SHANK AND HAVING A RELATIVELY WIDE BOTTOM SURFACE OVERLYING AND BEARING UPON AN AREA OF THE SAID DIAPHRAGM SEAL ASSEMBLY AND HAVING A VERTICAL INNER SURFACE SLOSELY OPPOSING THE SHANK, SAID BOTTOM AND INNER SURFACES OF SAID COLLAR TERMINATING SHORT OF INTERSECTION WITH ONE ANOTHER AND THEREBY FORMING AN ANNULAR SEAL RECEIVING SPACE AROUND THE SHANK, AN ANNULAR COMPRESSIBLE SEAL UNIT IN SAID ANNULAR SEAL RECEIVING SPACE AND HAVING AN UNSTANDING INNER SURFACE ENGAGING THE SHANK OF THE PLUG AND SECOND SURFACE NORMAL TO SAID FIRST SURFACE AND EXTENDING OUTWARDLY FROM THE LOWER PORTION THEREOF AND ENGAGING A PORTION OF THE TOP SIDE OF SAID DIAPHRAGM SEAL ASSEMBLY CLOSELY ADJACENT TO THE PLUG AND SHANK, AND MEANS FOR DRIVING SAID RIGID ANNULAR COLLAR TOWARD SAID TOP OF THE PLUG BODY AND THEREBY IMPOSING THRUST AGAINST SAID ANNULAR SEAL UNIT AND COMPRESSING THE LATTER AGAINST SAID DIAPHRAGM SEAL ASSEMBLY AND AGAINST SAID SHANK TO EFFECTIVELY PREVENT PASSAGE OF FLUID FROM WITHIN THE VALVE BODY ALONG THE TOP AND SIDE SURFACES OF THE PLUG AND SHANK RESPECTIVELY BETWEEN SAID RIGID COLLAR AND THE DIAPHRAGM SEAL ASSEMBLY, THE BEARING AREA OF SAID BOTTOM SURFACE OF SAID COLLAR UPON THE DIAPHRAGM SEAL ASSEMBLY BEING RADIALLY OUTWARDLY OF THE SEAL UNIT AND THE DIAPHRAGM SEAL ASSEMBLY BELOW SAID COLLAR BOTTOM SURFACE BEING VERTICALLY SPACED FROM THE TOP END OF THE ROTATY PLUG.