DIAPHRAGM VALVE
A diaphragm valve in which, even if a thrust force for sealing a valve seat is suppressed small, aligning capability of a diaphragm piece can be enhanced. The diaphragm valve has a diaphragm piece arranged so as to freely abut on a tip of a stem and causing a valve-close state in which a diaphragm is caused to abut on a valve seat via the diaphragm piece pushed by the stem to a valve-closing direction. The stem has a tip surface forming a spherical shape. The diaphragm piece is provided with a recessed portion where a tip portion of the stem is placed. The recessed portion has an inner bottom surface having a radius of curvature larger than a radius of curvature of the tip surface of the stem and forming a spherical shape with a center portion as a lowermost surface.
1 . A diaphragm valve having a diaphragm piece arranged so as to freely abut on a tip of a stem and causing a valve-close state in which a diaphragm is caused to abut on a valve seat via the diaphragm piece pushed by the stem to a valve-closing direction, wherein
the stem has a tip surface forming a spherical shape,
the diaphragm piece is provided with a recessed portion where a tip portion of the stem is placed, and
the recessed portion has an inner bottom surface having a radius of curvature larger than a radius of curvature of the tip surface of the stem and forming a spherical shape with a center portion as a lowermost surface.
2 . The diaphragm valve according to claim 1 , wherein
the inner bottom surface of the recessed portion is formed at a deeper position as long as a predetermined strength can be ensured.
3 . The diaphragm valve according to claim 1 , further comprising
a retaining member for movably retaining the diaphragm piece to an axial center direction of the diaphragm piece, wherein
the diaphragm piece has a height in the axial center direction so as to be able to be guided by the retaining member to the axial center direction by taking a side-portion outer circumferential surface of the diaphragm pieces as a sliding surface.
4 . The diaphragm valve according to claim 2 , further comprising
a retaining member for movably retaining the diaphragm piece to an axial center direction of the diaphragm piece, wherein
the diaphragm piece has a height in the axial center direction so as to be able to be guided by the retaining member to the axial center direction by taking a side-portion outer circumferential surface of the diaphragm pieces as a sliding surface.