Butterfly valve having resilient sealing means

Claim 1

A BUTTERFLY-TYPE VALVE, COMPRISING A CONDUIT DEFINING A FLOW PASSAGE, A CYLINDRICAL VALVE SEAT DISPOSED WITHIN THE CONDUIT AND ABOUT A PLANE NORMAL TO THE LONGITUDINAL AXIS OF THE FLOW PASSAGE, A BUTTERFLY DISC MEMBER DISPOSED WITHIN THE FLOW PASSAGE ALIGNABLE WITH THE VALVE AND HAVING AN OUTER PERIPHERAL DIMENSION SMALLER THAN THE VALVE SEAT, MOUNTING MEANS SPACED FROM SAID PLANE AND DIAMETRICAL OF THE VALVE ADAPTED TO ROTATE THE DISC MEMBER TO A VALVE CLOSED POSITION ALIGNED WITH THE VALVE SEAT AND TO A VALVE OPENED POSITION NORMAL TO SAID VALVE CLOSED POSITION, A FLEXIBLE ANNULUS OF SUBSTANTIALLY UNIFORM SECTION SECURED TO THE DISC MEMBER AND HAVING A GENERALLY CYLINDRICAL OUTER PERIPHERAL DIMENSION LARGER THAN THE VALVE SEAT AND SEATABLE THEREWITH IN THE VALVE CLOSED POSITION TO CLOSED THE FLOW PASSAGE, AND A RIGID ANNULUS SECURED TO THE DISC MEMBER ON THE DOWNSTREAM SIDE OF THE FLEXIBLE ANNULUS IN THE VALVE CLOSED POSITION, THE OUTER PERIPHERAL DIMENSION OF THE RIGID ANNULUS BEING SMALLER THAN THE VALVE SEAT AND DIVERGING OUTWARDLY FROM THE DISC MEMBER IN AN UPSTREAM DIRECTION IN THE VALVE CLOSED POSITION AGAINST THE FLEXIBLE ANNULUS TO SLOPE THE OVERLAPPING FLEXIBLE ANNULUS WITH RESPECT TO THE VALVE SEAT AND TO THE DISC MEMBER.