Airtightness maintaining structure for butterfly valve

摘要

An airtightness maintaining structure for a butterfly valve includes a valve element having a rotating shaft and a valve body, a rotation supporting portion having a pivotably supporting member that fits onto the rotating shaft and pivotably supports the rotating shaft, and a rotating shaft seal arranged to contact in a fitting state both an end surface of a member on an outer radial and a surface of a member on an inner side either the rotation shaft or the pivotably supporting member and has an annular portion. In a closed valve state of the valve element, the rotating shaft seal moves radially due to a pressure difference between a high fluid pressure acting on one side of the valve element and a low fluid pressure acting on the other side and contacts both the valve element and the rotation supporting portion on the high fluid pressure side.

主权项

1. An airtightness maintaining structure for a butterfly valve comprising:
a partition including an opening configured for fluid passage; a valve element including a rotating shaft and a valve body, the valve element being rotatably attached to the partition via the rotating shaft, the valve body being configured to switch the opening between an open valve state and a closed valve state by rotating with the rotating shaft; a rotation supporting portion having a pivotably supporting member that fits on the rotating shaft and pivotably supports the rotating shaft; a rotating shaft seal that is arranged so as to be able to contact in a fitting state with both (i) an end surface of a member on an outer side in a radial direction of the rotating shaft and (ii) a surface of a member on an inner side of either the rotation shaft or the pivotably supporting member; the rotating shaft seal being movable between the partition and the rotating shaft, and possessing an annular portion; and wherein, in the closed valve state of the valve element, the rotating shaft seal moves in the radial direction of the rotation shaft due to a difference of pressures between a high fluid pressure that acts on one side of the valve element and a low fluid pressure that acts on the other side thereof and contacts with both the valve element and the rotation supporting portion on the high fluid pressure side.