Abstract: A diaphragm valve and a flow rate control device for a semiconductor manufacturing apparatus are configured so as to allow an increase of a valve flow rate while avoiding an increase in size of the valve. The diaphragm valve includes a diaphragm with an outer periphery being pressed and a valve seat part in a valve chamber of a body having an inflow path and an outflow path, with the diaphragm being configured to open and close the valve chamber by an ascending/descending motion of a stem. The diaphragm has a substantially-flat cross sectional form having a substantially-planar center region and a boundary region. The boundary region is on an outer peripheral side of the center region and has a radius of curvature smaller than that of the center region, and the boundary region is positioned near an outer peripheral side of the valve seat part.

Abstract: A diaphragm valve includes a valve seat disposed in a valve chamber in a body, an annular groove provided on the outer periphery of the valve seat, a diaphragm provided so as to be able to make contact with and leave the valve seat via a pressurizing device, and a primary-side flow path communicating the valve chamber, in which an inner diameter of a secondary-side flow path contiguously provided to the annular groove is 2.0 to 4.5 times a groove width of the annular groove, and an intersection cross-sectional area between the annular groove and the secondary-side flow path is smaller than a cross-sectional area of the secondary-side flow path and the intersection cross-sectional area is configured to be equal to or larger than 35% with respect to a sectional area of the secondary-side flow path to acquire a predetermined Cv value.

Abstract: Provided is a valve actuator in a simple structure and easily downsizable, having reliable valve openability and closability even under high pressure, and also capable of exerting high durability even with a high frequency of valve opening and closing, and a diaphragm valve including this valve actuator. In the valve actuator, a repulsive member provided in an actuator main body, a piston pressed by this repulsive member, and at least two air chambers for moving the piston by an air pressure are arranged and a booster mechanism for exerting a force amplified in a valve-closing direction is accommodated in any of the air chambers.

Abstract: A diaphragm valve includes a valve seat (52) disposed in a valve chamber in a body (50), an annular groove (53) provided on the outer periphery of the valve seat, a diaphragm (55) provided so as to be able to make contact with and leave the valve seat via a pressurizing device, and a primary-side flow path (56) communicating the valve chamber, in which an inner diameter (R) of a secondary-side flow path (57) contiguously provided to the annular groove is 2.0 to 4.5 times a groove width of the annular groove, and an intersection cross-sectional area (S) between the annular groove and the secondary-side flow path is smaller than a cross-sectional area (T) of the secondary-side flow path and the intersection cross-sectional area is configured to be equal to or larger than 35% with respect to a sectional area of the secondary-side flow path to acquire a predetermined Cv value.

Abstract: Provided is a valve actuator in a simple structure and easily downsizable, having reliable valve openability and closability even under high pressure, and also capable of exerting high durability even with a high frequency of valve opening and closing, and a diaphragm valve including this valve actuator. In the valve actuator, a repulsive member provided in an actuator main body, a piston pressed by this repulsive member, and at least two air chambers for moving the piston by an air pressure are arranged and a booster mechanism for exerting a force amplified in a valve-closing direction is accommodated in any of the air chambers.

Abstract: Provided are a diaphragm valve and a flow rate control device for a semiconductor manufacturing apparatus simply and optimally configured so as to allow a reliable increase of a valve flow rate while avoiding an increase in size of the valve due to an increase in diameter of a valve seat, an increase in stroke, or the like and also allow durability and the life of the valve to be maintained or improved. That is, a diaphragm valve includes a diaphragm with an outer periphery being pressed and a valve seat part in a valve chamber of a body having an inflow path and an outflow path, this diaphragm is provided so as to be able to open and close the valve chamber by an ascending/descending motion of a stem.