| 摘要 |
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: according to one aspect of the invention, 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; according to another aspect of the invention, the cylinder head has an inlet passage extending outwardly from the piston cylinder and an inlet check valve is connected to this passage, an outlet passage extending outwardly from the piston cylinder, which is substantially axially offset with respect to the inlet passage along the center line of the piston cylinder to reduce the retention of trapped gas in the cylinder head and assists in obtaining a thorough flush of the cylinder head when changing solvents, and an outlet check valve connected to the outlet passage.
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