Butterfly valve seat ring and butterfly valve provided with same
A seat ring for a butterfly valve is mounted on an inner peripheral surface of an internal flow passage extending along the flow passage axis in a valve body of the butterfly valve, so that an outer peripheral edge surface of a valve element supported to be rotatable in the internal flow passage by a valve stem supported by the valve body abuts on the seat ring. The seat ring includes a ring body having a cylindrical shape and extending in the center axis direction, and the ring body is formed at positions opposite to each other in a radial direction of the ring body with a pair of through-holes for allowing the valve stem to pass through. On an outer peripheral surface of the ring body, arcuate projections extending in a circumferential direction are formed apart from the pair of through-holes.
1. A butterfly valve seat ring, adapted to be mounted on an inner peripheral surface of an internal flow passage extending along a flow passage axis and formed in a valve body of a butterfly valve, so that an outer peripheral edge surface of a valve element supported to be rotatable in the internal flow passage by a valve stem supported by the valve body abuts on the butterfly valve seat ring, said butterfly valve seat ring comprising:
a ring body extending in a center axis direction of the ring body and having an outer peripheral surface,
a pair of through-holes penetrating the ring body, through which the valve stem is adapted to pass,
two flange portions extending radially outwardly from end portions of the ring body in the center axis direction thereof, and
two arcuate projections formed on the outer peripheral surface of the ring body between the two flange portions and extending in a circumferential direction of the ring body, each of the two arcuate projections including curved portions at end portions thereof apart from the pair of through-holes to be smoothly connected to the outer peripheral surface of the ring body.
2. The butterfly valve seat ring according to claim 1 , wherein the outer peripheral surface of the ring body has an oval shape and an inner peripheral surface of the ring body has a circular shape, so that each of the portions where the pair of through-holes is formed has a thickness thicker than another portion.
3. The butterfly valve seat ring according to claim 1 , wherein each of the two arcuate projections has a rectangular shape in a cross section thereof.
4. The butterfly valve seat ring according to claim 2 , wherein each of the two arcuate projections has a rectangular shape in a cross section thereof.
5. A butterfly valve comprising:
a valve body having an internal flow passage extending along a flow passage axis inside the valve body;
the seat ring according to claim 1 mounted on an inner peripheral surface of the internal flow passage;
a valve stem extending through the pair of through-holes of the seat ring; and
a valve element having a disk shape and supported to be rotatable in the valve body by the valve stem,
wherein the seat ring is mounted on the inner peripheral surface of the internal flow passage of the valve body in a state where each of the two arcuate projections formed on the outer peripheral surface of the seat ring is fitted to an arcuate groove formed on the inner peripheral surface of the internal flow passage of the valve body, and the valve element is rotated in the valve body so that an outer peripheral edge surface of the valve element is brought into pressure contact with or separated from an inner peripheral surface of the seat ring, thereby opening and closing the valve.
6. The butterfly valve according to claim 5 , further comprising a bush inserted into and fitted to each of the pair of through-holes.
7. The butterfly valve according to claim 1 , wherein each of the two arcuate projections extends from a center position between the pair of through-holes in the circumferential direction of the ring body to positions at angles of plus and minus 45 degrees around the center axis of the ring body from the center position between the pair of through-holes.
8. The butterfly valve according to claim 1 , wherein each of the two arcuate projections has a center portion between the pair of through-holes in the circumferential direction of the ring body, and
each of the curved portions is arranged at a middle portion between each of the pair of through-holes and the center position of each of the two arcuate projections.
9. The butterfly valve according to claim 7 , wherein each of the curved portions includes a convex curved portion, and a concave curved portion connecting the convex curved portion and the outer peripheral surface of the ring body and having a curvature smaller than that of the convex curved portion to minimize a difference in distribution of seal pressure, and
the ring body further includes tab portions extending in a direction approaching each other from outer peripheral edge portions of the two flange portions adapted to engage the valve body.