Encapsulated plug valve

Claim 2

A plug valve comprising: a valve body having inlet and outlet ports and an intermediate body cavity circular in cross section, a valve plug rotatably mounted in said body cavity, a transverse flow passageway through said plug for alignment with said body ports in open position of the valve, and an imperforate surface intermediate said flow passageway openings for alignment with said body ports in closed position of the valve, said imperforate surface being of resilient material, at any given level between a top level above and a bottom level below said flow passageway openings, upright strips of said imperforate surface adjacent said openings, when undeformed, are coaxial with, and of a radius slightly larger than, the corresponding surface of said body cavity to form sealing strips, said imperforate surface between said strips being contained within a projected circumferential continuation of said sealing strips and being of radius at each level larger than that of said sealing strips, with the center thereof displaced more remote therefrom than the axis of said plug.

Claim 3

The plug valve defined by claim 1 wherein: the amount of displacemeNt of said center from the axis of said plug is greater than the difference between the radii of the intermediate surfaces and sealing bands.

Claim 4

The plug valve defined by claim 1 wherein: there are circumferential bearing surfaces on said plug at levels above said top level and below said bottom level circular in cross section.

Claim 5

The plug valve defined by claim 3 wherein: said circumferential bearing surfaces when undeformed are of slightly larger radii than corresponding levels of the surface of said body cavity.

Claim 6

The plug valve defined by claim 3 wherein: said body cavity is tapered in frustoconical configuration to a smaller diameter at the bottom, said sealing strips have a complementary taper merging with said circumferential bearing surfaces at top and bottom, and including transitional portions tapered inward from said bearing surfaces to said intermediate surfaces.

Claim 7

A plug valve comprising: a valve body having inlet and outlet ports and an intermediate body cavity circular in cross section, a valve plug rotatably mounted in said body cavity, a transverse flow passageway through said plug for alignment with said ports in open position of the valve, a coating of resilient material encapsulating said valve plug, circumferential bearing surfaces around said plug at the top and bottom thereof of a radius at each level slightly larger than the corresponding radius of said body cavity, and a pair of upright convex arcuate sealing strips on said imperforate portions coaxial with said bearing surfaces and extending therebetween and merging therewith, said sealing strips being separated an amount greater than the width of a body port, the radii of said convex sealing strips being slightly larger than corresponding radii of said body cavity, other surfaces of said imperforate portion when undeformed being contained within a projection of said convex sealing strips, said valve cavity being tapered inward from top to bottom in frustoconical configuration, the rotation of said convex sealing strip about the axis of said plug would generate a frustoconical surface with diameters when undeformed slightly larger than corresponding diameters of said body cavity, said imperforate portion intermediate said sealing strips being a conical surface generated by rotation of a similarly sloped line about an axis more remote therefrom than the axis of said plug, and the radius of said intermediate portion at any level thereof being greater than the radius of said sealing strips by an amount less than the displacement of the axis thereof from the axis of said plug.

Claim 8

A plug valve comprising: a valve body having inlet and outlet ports and an intermediate body cavity circular in cross section, a valve plug rotatably mounted in said body cavity, a transverse flow passageway through said plug for alignment with said ports in open position of the valve, a coating of resilient material encapsulating said valve plug, circumferential bearing surfaces around said plug at the top and bottom thereof of a radius at each level slightly larger than the corresponding radius of said body cavity, and a pair of upright convex arcuate sealing strips on said imperforate portions coaxial with said bearing surfaces and extending therebetween and merging therewith, said sealing strips being separated an amount greater than the width of a body port, the radii of said convex sealing strips being slightly larger than corresponding radii of said body cavity, other surfaces of said imperforate portion when undeformed being contained within a projection of said convex sealing strips, said valve cavity being tapered inward from top to bottom in frustoconical configuration, the rotation of said convex sealing strip about the axis of said plug would generate a frustoconical surface with diameters when undeformed slightly larger than corresponding diameters of said body cavity, said imperforate portion intermediate said sealing strips being a conical surface generated by rotation of a similarly sloped line about an axis more remote therefrom than the axis of said plug, and the radius of said intermediate portion at any level thereof being greater than the radius of said sealing strips by an amount less than the displacement of the axis thereof from the axis of said plug.