Automatic controlling valve for maintaining the rate of fluid flow at a constant value

An automatic fluid control valve for maintaining a substantially constant fluid flow rate comprising:

• a valve casing having an inlet for the introduction of fluid thereinto and an outlet for discharge of fluid therefrom;
• a partition wall within said casing between said fluid inlet and said fluid outlet, said partition wall having a valve port therein establishing communication between said fluid inlet and said fluid outlet, said partition wall including a horizontally extending portion in which said valve port is formed, said partition wall subdividing said valve casing into an inlet chamber and an outlet chamber located on the opposed sides thereof;
• a restriction adjusting member mounted movably in a wall of said valve casing and including a tapered end movable relative to said valve port to define a restricted passageway for fluids with the adjacent walls of said valve port, said restricted passageway being of variable cross-sectional area settable to establish a predetermined fluid flow rate through the control valve located intermediate said fluid inlet and said outlet and thereby establishing first and second fluid pressures respectively on the upstream and downstream sides of said restricted passageway,
• a valve stem movable linearly within said casing and having valve means thereon cooperable with said valve port to regulate the flow of fluids therethrough in response to changes in fluid pressure differential, said valve stem having a valve plug at the lower end thereof cooperable with said valve port at the side thereof opposite from said restriction adjusting member, said restriction adjusting member being movable to establish a predetermined cross-sectional flow area for said restricted passageway for fluids,
• a spring case mounted on said valve casing extending outwardly thereof to enclose the upper portion of said valve stem,
• diaphragm means operatively connected to said valve stem and separating a region within said valve casing into a pair of pressure-differential chambers, said diaphragm being a bellows-diaphragm the peripheral edge of which is positioned between said valve casing and a flange integral with said spring case to thereby provide one pressure-differential chamber thereabove and another pressure-differential chamber therebelow, and
• means comprising a flow passage formed in said casing and spring case communicating said one pressure-differential chamber with said inlet chamber, said other pressure-differential chamber communicating with the downstream side of said valve port.