Diaphragm member and diaphragm valve provided with diaphragm member

A diaphragm valve for flowing a liquid such as a high-purity chemical liquid, an ultrapure water or the like from an inflow side to an outflow side when opened at a valve portion thereof and blocking the flowing of the liquid when closed at the valve portion thereof, which comprises:

• a housing including a cylindrical peripheral wall and both opposing walls formed opposite to each other on said cylindrical peripheral wall so as to close axial opening end portions of said cylindrical peripheral wall,
• a partition wall provided on an axial intermediate portion of said cylindrical peripheral wall to divide a hollow portion of said cylindrical peripheral wall between one opposing wall of said both opposing walls and the other opposing wall,
• a driving unit assembled in the hollow portion of said cylindrical peripheral wall between the one opposing wall and said partition wall, and
• a diaphragm member including a film-like diaphragm of PFA and a valve body of fluorine resin,
• wherein in said diaphragm member,
• said film-like diaphragm is formed with a central hole portion at its central portion, said film-like diaphragm being provided so as to form a liquid chamber between the other opposing wall in said housing and an air chamber between said partition wall in said housing, thereby to divide the interior of said housing,
• said valve body is joined at its base portion by laser welding to the central hole portion of said diaphragm from a lower surface side of said diaphragm, said valve body extending from the central hole portion into the liquid chamber,
• said housing is provided with an annular valve seat, an inflow path and an outflow path in the other opposing wall, said annular valve seat opposing said valve body in the liquid chamber to construct the valve portion with said valve body, said inflow path flowing the liquid from the inflow side into the liquid chamber through said annular valve seat, and said outflow path flowing the liquid in the liquid chamber to the outflow side,
• said driving unit is provided integrally with a driving shaft coupled with the base portion of said valve body through the central hole portion of said diaphragm from an upper surface side of said diaphragm so as to be axially movable with said valve body of said diaphragm member toward said annular valve seat or in the opposite direction, and
• said diaphragm member closes the valve portion when said valve body is seated on said annular valve seat while displacing said diaphragm in a curved shape in conjunction with the axial movement of the driving shaft to the side of the other opposite wall, said diaphragm member opening the valve portion when said valve body is separated from said annular valve seat while displacing said diaphragm in a curved shape in conjunction with the axial movement of the driving shaft to the side of the one opposite wall.