Butterfly valve and stem assembly

Abstract

A butterfly valve capable of preventing leakage under demanding environmental and operating conditions. The valve includes two stem seal assemblies. The stem seal assemblies include a first pusher, a first energizer, a second pusher, a second energizer, and a force transmitting member. The force transmitting member is configured to transfer an axial load to the second pusher, which causes the first and second energizer to expand radially to create a secondary and tertiary seals between the stem seal assembly and valve stem. In addition, the force transmitting member is configured to transfer an axial load to the first pusher which creates a primary seal.

We claim: 
     
         1 . A valve comprising:
 a body having a first port, a second port, and a media passage extending between said first port and second port, said body further comprising a stem port;   a flow element positioned in said media passage, said flow element having an open position and a closed position, wherein said flow element is configured to allow media to flow through said media passage when said flow element is in said open position and configured to prevent media from flowing through said media passage when said flow element is in said closed position;   a stem positioned in said stem port and secured to said flow element and to an actuator, wherein said actuator is configured to move the flow element between said open position and said closed position; and   a sealing assembly adjacent to the stem and configured to fit within an annular space between the stem and the body, the sealing assembly comprising a primary seal having inner and outer circumference walls, wherein said inner and outer circumference walls define a cavity; a primary shaft insert configured to fit within said cavity, and a force transmitting member configured to continuously transfer an axial load to the primary shaft insert and wherein said primary shaft insert is configured to transfer said axial load radially to said primary seal to create a seal between the body and the stem.   
     
     
         2 . A valve according to  claim 1  wherein the force transmitting member comprises one or more Belleville springs. 
     
     
         3 . A valve according to  claim 1  wherein the primary seal is comprised of thermoplastic or fluoroplastic. 
     
     
         4 . A valve according to  claim 1  wherein the primary seal is comprised of polytetraflouroethylene, flourinated ethylene propylene, perfluoroalkoxy, polyvinyledeneflouride, and combinations thereof. 
     
     
         5 . A valve according to  claim 1  wherein the primary shaft insert is comprised of synthetic rubber, fluoropolymer elastomers, and combinations thereof. 
     
     
         6 . A valve according to  claim 1  wherein said actuator is positioned external to said body.