Pilot operated control valve

Claim 1

A pilot operated control valve for limiting flow between a main line and a discharge line, moveable diaphragm means interposed between the main line and said discharge line for directly establishing the flow therebetween as a function of its position, the diaphragm means having an orifice leading into a poppet chamber having an opening and outlet means, a poppet including a tapered portion passing through said opening and projecting into said chamber, a linear motor to drive said poppet, said motor including an armature to which said poppet is connected means for variably positioning said poppet in said opening in order to vary the effective area of said opening by the movement of said poppet, said outlet means having a maximum effective area of ten times the area of said opening, said opening leading to a control chamber, said outlet means connecting the control chamber to said discharge line whereby a small portion of the flow from the main line, which portion is denominated as the control flow and is a function of the area of the opening in the poppet chamber, is diverted through said diaphragm orifice, through said poppet opening, into said control chamber and then to said discharge line through said outlet means, the position of said diaphragm for any steady state condition varying linearly with the coefficient (1-(AO/Ac)2)/( 1+(AO/Ac)2) wherein AO is the area of the opening in the poppet chamber and Ac is the area of the outlet means.