Patent ID: 7628376

Claim:
A diaphragm valve comprising: a valve seat being formed at a boundary between a first flow passage and a second flow passage which are formed in a body; a diaphragm being coupled to a driving shaft of an actuator to be brought into/out of contact with the valve seat to close/open between the first flow passage and the second flow passage, wherein the diaphragm includes a valve element body movable into contact with the valve seat, a web portion extending outward from the valve element body, and a fixed portion formed at a peripheral edge of the web portion, the web portion includes a vertical portion vertically formed continuous with the valve element body, a curved portion connected to a top end of the vertical portion, and a connecting portion that connects the curved portion with the fixed portion, the web portion having a portion out of contact with the valve element body and a backup both in a valve-opened state and a valve-closed state, the curved portion being less in contact with the driving shaft in a valve-opened state as opposed to a valve-closed state, the vertical portion being of substantially a same length in both the valve-opened state and the valve-closed state, and substantially all of the vertical portion being in contact with the driving shaft in both the valve-opened state and the valve-closed state.