Flow control valve

Claim 1

A valve comprising: (a) a housing having an inlet and an outlet, a flow passage interconnecting said inlet and said outlet and defining a longitudinal axis therein: (b) a valve seat in said passage, said valve seat defining a plane which forms an obtuse angle with said longitudinal axis relative to the flow direction from said inlet; (c) a cavity in said housing in communication with said passage; (d) a moveable diaphragm disposed across said cavity to define a diaphragm control cavity on one side of said diaphragm, with the other side of said diaphragm in fluid communication with said passage; (e) control means for varying the fluid pressure in said diaphragm control cavity to control the position of said diaphragm, said control means including fluid passages in said valve housing communicating said control cavity with said flow passage and means for controlling the flow of fluid from said control cavity, said diaphragm being moved outwardly of said control cavity as fluid is introduced into said control cavity, and said diaphragm being moved inwardly into said control cavity as fluid is passed from said control cavity; (f) a flapper closure element pivotally disposed in said housing and adapted to cooperate with said valve seat to stop flow through said flow passage when said closure element abuts said valve seat, and to permit flow through said flow passage when said closure element is spaced from said valve seat; (g) means connecting said closure element with said diaphragm such that as said diaphragm is displaced inwardly into said control cavity, said closure element is moved away from said valve seat by said connecting means and said diaphragm to permit fluid flow through said flow passage, and said closure element is moved toward said valve seat by fluid flowing into said passage from said inlet as the diaphragm is displaced outwardly from said control cavity to restrict fluid flow through said fluid passage; and, (h) means operatively coupled to said diaphragm and said connecting means to permit movement of said closure element away from and towards said valve seat, independently of movement of said closure element by said diaphragm in response to fluid pressure within said control cavity, to provide adjustment of the position of said closure element in the open mode of the valve and to permit opening and closing of the valve independently of the operation of said diaphragm.