Valve seat

Claim 1

A VALVE SEAT FOR A VALVE MEMBER HAVING A SPHERICALLY SHAPED SURFACE COMPRISING: A SLEEVE FABRICATED OF METAL AND HAVING FIRST AND SECOND ENDS; A FLUID ORIFICE COMMUNICATING BETWEEN THE FIRST AND SECOND ENDS; A FIRST COUNTERBORE OF GREATER DIAMETER THAN THE FLUID ORIFICE EXTENDING FROM THE SECOND END TO A POINT INTERMEDIATE THE ENDS OF THE SLEEVE AND FORMING A FIRST ANNULAR SEATING SURFACE AROUND THE FLUID ORIFICE BETWEEN THE ORIFICE AND THE FIRST COUNTERBORE; A SECOND COUNTERBORE OF GREATER DIAMETER THAN THE FIRST COUNTERBORE EXTENDING FROM THE SECOND END OF THE SLEEVE TO A POINT SPACED INWARDLY FROM SAID SECOND END AND FORMING A SECOND ANNULAR SEATING SURFACE BETWEEN THE FIRST AND SECOND COUNTERBORES; THE FIRST AND SECOND ANNULAR SEATING SURFACES BEING DIMENSIONED AND POSITIONED TO LIE IN AN IMAGINARY FRUSTO-CONICAL SURFACE TO SIMULTANEOUSLY SEAT THE VALVE MEMBER ALONG SUBSTANTIALLY LINEAR ZONES OF CONTACT; A BODY OF RESILIENT MATERIAL FILLING THE FIRST COUNTERBORE BETWEEN THE FIRST AND SECOND ANNULAR SEATING SURFACES TO FORM A RESILIENT THIRD ANNULAR SEATING SURFACE LYING IN, AND FORMING A PORTION OF, SAID IMAGINARY FRUSTO-CONICAL SURFACE WHEREBY SAID RESILIENT SEATING SURFACE TANGENTIALLY CONTACTS SAID VALVE MEMBER BEFORE SAID VALVE MEMBER CONTACTS SAID FIRST AND SECOND ANNULAR SEATING SURFACES.