Butterfly valve of large diameter

Claim 1

A butterfly valve of large diameter, comprising: a cylindrical body having a substantially cylindrical inner bore defined at its outer ends by spaced-apart parallel side walls and being lined in its interior with an elastic seat in the form of a ring that terminates at said parallel side walls of said valve body; said ring having a substantially U-shaped cross-section that conforms to the configuration of said bore; a butterfly pivotally mounted in said body by means of valve spindles that pass through said body and said ring; wherein said body includes at least two annular grooves, each of which having an opening at its innermost end into said bore, and being closed at its outermost end; said grooves being coaxial with respect to said bore, opening thereinto, and being narrower at said innermost ends than at said outermost ends; said ring being constructed of a plurality of sections that are disposed in an end-to-end relationship, said sections including two sections having a curvilinear outer shape for the passage of said valve spindles and of the valve, and a plurality of rectilinear sections; the ends of said sections being formed and vulcanized to shape after having been aligned with each other; said ring further including, on its side adjacent said body, at least two annular tenons that have heads which respectively engage said grooves; said tenons being smaller than said openings of the grooves; and wherein an empty space is provided between said tenons and said grooves, said empty space being filled with a plastic material that hardens by polymerization, to retain said ring in said body.