Dual-piston reciprocating pump assembly

Abstract

The invention is directed to a dual-piston reciprocating pump assembly which includes two opposed substantially identical reciprocating pumps, a housing within which the pumps are mounted, a cam mounted on a cam shaft which is driven through a coupling by a stepping motor, each of the pumps including a piston assembly comprising a piston body having a piston end, the other end of the piston body being in the form of a yoke which is mounted for reciprocating motion in the housing, a cam follower carried between the arms of the yoke for engaging the cam face of the cam, a cylinder head having a piston cylinder therein for receiving the piston end, the housing having an end opening for receiving said cylinder head, a guide bushing mounted in the cylinder head for facilitating the assembly of the piston end, an inner bearing bore for the piston end disposed adjacent the guide bushing, a high-pressure seal disposed adjacent the inner bearing bore, the piston end having substantial radial end play, and a piston spring mounted for urging the piston inwardly to maintain the cam follower in engagement with the cam face. The cam face profile is shaped to synchronize the pistons for pumping and filling to minimize pressure pulsations and produce a substantially constant flow of fluid. Axially offset inlet and discharge passage communicate with the cylinder to reduce retension of trapped gas and throughly flush the cylinder.