Patent ID: 7694939

Claim:
A flow rate control valve including a float rod inserted into a valve hole so that said float rod is capable of making reciprocating movement, said valve hole being formed in a valve housing having a fluid-introducing port and a fluid-discharging port, wherein a valve plug provided on said float rod opens and closes a valve seat, said flow rate control valve further comprising: a fixed cylinder into which said float rod is inserted and which has a screw section formed on an outer circumferential surface thereof; a retaining cylinder which has, on an inner circumferential surface thereof, a screw section threadedly engaged with said screw section of said fixed cylinder, and which is displaceable in an axial direction with respect to said fixed cylinder by rotational displacement thereof; a cover member installed between said fixed cylinder and said float rod, and which is capable of expanding and contracting in said axial direction; a first pressure-receiving section provided on one end of said float rod; and a second pressure-receiving section provided on another end of said float rod, and which has a pressure-receiving area equal to that of said first pressure-receiving section, wherein stopper mechanisms are disposed on said retaining cylinder at an uppermost position and a lowermost position thereof, for restricting the rotational displacement of said retaining cylinder which occurs when said retaining cylinder is displaced in said axial direction along said fixed cylinder.