Patent ID: 7163024

Claim:
A flow control valve comprising: an air chamber having two openings opposite each other; two diaphragms mounted to the openings of said air chamber and having pressurized surfaces with different areas that receive pressure of the air chamber; a connecting shaft that connects said two diaphragms; support means that supports said connecting shaft slidably in an axial direction; an internal channel that is provided outside said air chamber and through which a fluid flows; a valve body that slides in conjunction with the sliding operation of said connecting shaft to increase or decrease a flow rate of the fluid flowing through said internal channel; and an air supply passage that supplies air whose pressure or flow rate is controlled into said air chamber, wherein said air supply passage is divided at one end thereof into two branch duct lines, one of the two branch duct lines opens at an outlet thereof so as to face the pressurized surface of one of said diaphragms in close proximity, and the other of the branch duct lines opens at an outlet thereof so as to face the pressurized surface of the other of said diaphragms in close proximity.