FLUID SEAL STRUCTURE

摘要

SEAL STRUCTURE A sealing structure capable of various uses and particularly in butterfly valves having a body with a flow passage and a movable valve disc in the flow passage and having a sealing surface. The sealing structure is mounted in the body to engage the disc in the closed position of the latter to provide a high performance (i.e. bubble-tight) seal. The sealing structure includes an annular seal retaining cavity with a slot opening to the flow passage. The structure includes a seal ring of Teflon PFA or the like retained in the cavity and sealing one axial side of the ring from the other. It also has a tongue-like extension projecting through the slot into the passage and having a seat at its end engageable with the sealing surface of the disc. The seal and cavity structures have shoulders normally (in open position of the valve) abutting each other to seal the interior of the cavity (the abutment occurring from expansion of the seal ring into place in the cavity). When the disc radially moves the tongue and seat it also separates the shoulders. Radial spaces are normally provided at opposite sides of the ring and the adjacent sides of the cavity. At the end opposite the slot and tongue the cavity terminates in an anchoring and sealing groove for an extending terminal end of the seal ring. Intermediate the radial spaces and the anchoring groove terminal end are adjacent convergent cavity and ring walls that normally barely abut or are in close proximity to each other. A core of substantial cross-section is located within the main body portion of the ring. When the valve is closed the convergent surfaces are engaged, the main body portion of the ring and the core are compressed and expanded to apply a radially directed force to the tongue and seat forcing them against the disc to effect a static seal. When fluid pressure is applied, the pressure acts in the space at that upstream side between the interior of the cavity and the adjacent exterior of the ring. This results in the ring and core producing an increased radially directed sealing force against the disc.