Servo-operated fluid flow control valve.

摘要

A fluid flow control valve including a resilient diaphragm member (10) defining within the valve housing (8,12) a chamber (A) to which fluid is admitted through an orifice (28) from a fluid inlet (4). The diaphragm member (10) includes a closure plate (16) which is engageable with a valve seating surface (18) leading to a fluid outlet (6) to close the control valve. The orifice (28) is positioned outside the perimeter of the seating region of the closure plate (16) to permit outflow of fluid from the chamber (A) to the outlet (6) when the closure plate (16) is spaced from the valve seating surface (18). There is a control member (22) positioned within the chamber (A) to control the position of the closure plate (16). The relative position of the control member (22) to the closure plate (16) remains constant during regulating movements of the control member (22) while the closure plate (16) is out of sealing contact with the seating surface (18) of the outlet (6).