| 摘要 |
PROBLEM TO BE SOLVED: To surely secure water-tight and air-tight states in a butterfly valve of an eccentric structure.SOLUTION: A butterfly valve includes: a valve chest 1 provided with a flow channel inside thereof, a valve element 2 disposed in the flow channel of the valve chest 1 to open and close the flow channel; a rotating shaft 3 eccentric to a flowing direction of the flow channel from a valve element face of the valve element 2, eccentric to one of inner wall face sides of the flow channel from the center of the valve element 2, and rotating the valve element 2; a valve chest valve seat 4 disposed at an inner diameter side of the valve chest 1 while applying, as a contact face, a virtual elliptical conical face f1 surrounded by both planes obtained by cutting the virtual elliptical conical face f1 having an apex on a position eccentric from a center axis of the flow channel, and having a short axis along the eccentric direction from the center axis inclined to the center axis, by two sheets of planes vertical to the center axis and separated from each other by a prescribed distance; and a valve element valve seat 5 having an outer peripheral end portion 5b facing the valve chest valve seat 4, of the circular arc-shaped cross section, and kept into contact with the contact face disposed on the outer peripheral edge of the valve element 2.SELECTED DRAWING: Figure 1 |
