Reciprocating pump wit pilot control valve

摘要

A pilot control valve for controlling a reciprocating pump having a valve member shiftable within a valve body between a first or "downstroke" position and a second or "upstroke" position. When the valve member is in its first position, the valve member allows communication of control fluid to the lower surface of a piston to move the piston from a first position to a second position. As the piston reaches its second position, a vent in a rod attached to the piston allows control fluid acting on the valve member to depressurize. As such control fluid is depressurized, pressurized control fluid acts on the valve member to move the valve member from its first position to its second position. In its second position, the valve member blocks communication of the control fluid to the lower surface of the piston and allows communication of the control fluid to the upper surface of the piston causing the piston to return to its first position. As the piston returns to its first position, the vent in the piston rod allows the pressurized control fluid acting on the upper surface of the piston to act on the valve member to move the valve member back to its first position. In its first position, the valve member blocks communication of the control fluid to the upper surface of the piston and allows communication of the control fluid to the lower surface of the piston and the process is repeated. In this manner, the pilot control valve of the present invention achieves a consistent pumping rate for a reciprocating device coupled to the pilot control valve.