Rotary plug valve

Claim 1

A rotary plug valve comprising: a housing member having a circular tapered valve seat provided with at least one flow port; a tapered plug member rotatable in said seat and having a flow passage terminating in at least one radial port movable into or out of registration with said seat port to open or close the valve; resilient rubberlike cover means for and secured to the circumference or an axial section of said valve seat and surrounding said seat port so as to contact the opposed surface of said plug; means defining at least one circumferential packing groove in one of the opposed surfaces of said members adjacent each end of said seat; a pressure-deformable resilient packing ring in each of said grooves of sufficient size in radial section to contact both the bottom of its groove and the other of said surfaces to form a fluid-tight seal therebetween; interengageable means associated with said members for retaining said plug member in operative relation with said seat when said plug member is in its open or closed positions and during rotation therebetween, said interengageable means also being operative to effect axial movement of said plug, relative to said seat and said cover means carried thereby, during rotation of said plug member between its open and closed positions, said axial movement of said plug member being toward the larger end of the seat during rotation thereof from the closed to the open position and toward the smaller end of the seat during rotation thereof from the open to the closed position, whereby said resilient cover means will be compressed between the opposed surfaces of said members to provide a fluidtight seal therebetween when the valve is in the closed position and the compression of said resilient cover means will be progressively reduced during rotation of said plug member from said closed to said open position.