Ball valve and method of making same

Claim 1

A BALL VALVE COMPRISING, IN COMBINATION, A VALVE BODY DEFINING AN INTERNAL VALVE CHAMBER AND TWO FLOW PASSAGES OPENING INTO SAID CHAMBER ON OPPOSITE SIDES THEREOF, TWO VALVE SEATS ENCIRCLING THE INNER ENDS OF SAID RESPECTIVE FLOW PASSAGES, A MOLDED FLOW CONTROL VALVE BALL INTERVENING BETWEEN SAID SEATS, SAID BALL DEFINING A FLOW FACE SLIDABLY ENGAGING THE SEATS, SAID BALL DEFINING A FLOW BORE EXTENDING THERETHROUGH FOR PASSING FLUID THERETHROUGH BETWEEN SAID PASSAGES, OPERATING MEANS COACTING WITH SAID BALL TO ROTATE THE LATTER ABOUT AN AXIS OF ROTATION THEREOF BETWEEN AN OPEN VALVE POSITION IN WHICH OPPOSITE ENDS OF SAID BALL BORE COMMUNICATE WITH SAID RESPECTIVE PASSAGES AND A CLOSED VALVE POSITION IN WHICH OPPOSITE ENDS OF SAID BORE ARE TURNED AWAY FROM SAID PASSAGES SO THAT COMMUNICATION BETWEEN SAID PASSAGES IS BLOCKED BY THE BALL, SAID BALL BEING FREE TO MOVE UNDER THE FORCE OF FLUID PASSAGE THEREON TOWARD THE ONE OF SAID PASSAGES WHICH CONTAINS THE LOWER FLUID PRESSURE SO THAT THE DIFFERENTIAL FORCE OF FLUID PRESSURE ON THE BALL URGES THE EXTERIOR SURFACE OF THE BALL AGAINST THE SEAT INCIRCLING THE INNER END OF THE PASSAGE UNDER THE LOWER PRESSURE; THE ENTIRE AREA OF SAID EXTERIOR SURFACE OF SAID BALL, WHICH COMES IN CONTACT WITH SAID SEATS FOR ALL NORMAL OPERATING POSITIONS OF THE BALL, BEING CURVED WITH A SINGLE CENTER OF CURVATURE AND A COMMON AND ACCURATELY FORMED SPHERICAL CURVATURE, EXCEPT FOR THOSE PORTIONS OF SAID EXTERIOR BALL SURFACE LOCATED WITHIN AN ANNULAR BAND INTERRUPTED DBY OPPOSITE ENDS OF THE BALL BORE AND BEING CONCENTRIC WITH RESPECT TO AN AXIS THAT EXTENDS THROUGH THE CENTER OF THE BALL IN GENERALLY PERPENDICULAR RELATION TO BOTH THE AXIS OF THE BALL BORE AND THE AXIS OF ROTATION OF THE BALL; PORTIONS OF SAID EXTERIOR BALL SURFACE LOCATED WITHIN SAID BAND BEING DEPRESSED SOMEWHAT IN RELATION TO THE SPHERICAL CURVATURE OF ADJACENT PORTIONS OF THE EXTERIOR BALL SURFACE TO PROVIDE BETWEEN SAID SPHERICAL CURVATURE AND THE EXTERIOR BALL SURFACE WITHIN SAID BAND RADIAL CLEARANCE FOR THE ACCOMODATION FO FLASHING PROTUBERANCES MOLDED ON THE BALL WITHIN THE BAND, THE PORTIONS OF THE EXTERIOR BALL SURFACE DEPRESSED WITHIN SAID BAND MERGING SMOOTHLY WITH ADJACENT PORTIONS OF THE BALL SURFACE ON OPPOSITE SIDES OF THE BAND AND BEING SHAPED TO AVOID A CONCAVE SHAPING OF THE SURFACE WITHIN THE BAND AS VIEWED TRANSVERSELY IN RELATION TO THE BAND, SAID VALVE SEATS DEFINING ANNULAR SEAT SURFACES CONFRONTING SAID BALL FOR SEALING ENGAGEMENT THEREWITH, SAID BAND HAVING A TRANSVERSE WIDTH THAT IS LIMITED IN RELATION TO SIZES OF SAID BALL AND BALL BORE AND IN RELATION TO THE WIDTH AND DIAMETER OF THE SEAT SURFACE OF EACH VALVE SEAT SO THAT THE BALL BORE COMMUNICATES AT LEAST PARTIALLY WITH SAID FLOW PASSAGES AT ALL TIMES WHEN THE BALL IS POSITIONED ROTATABLY TO ENGAGE WITH SAID SEAT SURFACES THE EXTERIOR BALL SURFACES WITHIN SAID BAND.,