Dual piston pump assembly with Anti-rotation guide rails

Abstract

A dual piston-pump apparatus is provided having a pump chassis that includes a pair of spaced-apart, elongated piston bores, and a lead screw shaft. This shaft includes a motor driven end, and another portion thereof rotatably mounted to the chassis for rotation about a screw rotational axis. A piston drive member threadably cooperates with the lead screw shaft for selective reciprocating movement longitudinally along the screw rotational axis thereof between a first position and a second position. The drive member includes a pair of spaced-apart piston shafts, each piston shaft of which includes a respective piston head slideably received in a respective piston bore of the chassis. As the drive member is driven along the screw shaft between the first position and the second position, each piston head is simultaneously reciprocated between a dispensing condition and an aspiration condition. An anti-rotation device cooperates between the pump chassis and the drive member to substantially prevent rotational displacement of the drive member relative to the pump chassis and about the screw rotational axis during rotational motion of the screw shaft.

Description

RELATED APPLICATIONS[0001]This application claims priority under 35 U.S.C. §119(e) from co-pending U.S. Provisional Patent Application No. 61 / 194,299, filed Sep. 25, 2008, and further claims priority from co-pending U.S. Provisional Patent Application No. 61 / 100,225, filed Sep. 25, 2008, both entitled “DUAL PISTON PUMP ASSEMBLY WITH ANTI-ROTATION GUIDE RAILS”, and naming Servin et al. as the inventors, and both of which are incorporated herein by reference in their entirety and for all purposes.FIELD OF THE INVENTION[0002]The present invention relates to dual pump assemblies, and more particularly, relates to dual pump assemblies that accurately deliver fluids at different delivery pressures.BACKGROUND OF THE INVENTION[0003]Syringe style pumps commonly consist of a single motor, a syringe barrel and a piston configuration. Typically, these pumps are of the single channel type for pumping a single liquid only. When multiple liquids are required for dispensing, however, such as two or...

AI Technical Summary

Benefits of technology

[0006]The present invention provides a dual piston-pump apparatus including a pump chassis assembly having a pair of spaced-apart, elongated piston bores, and a lead screw shaft. This shaft includes a motor driven end, and another portion thereof rotatably mounted to the chassis assembly for rotation about a screw rotational axis. A piston drive member threadably cooperates with the lead screw shaft for selective reciprocating movement longitudinally along the screw rotational axis thereof between a first position and a second position. The drive member includes a pair of spaced-apart piston shafts, each piston shaft of which includes a respective piston head portion slideably received in a respective piston bore of the chassis assembly. As the drive member is driven along the lead screw shaft between the first position and the second position, each piston head is simultaneously reciprocated between a dispensing condition and an aspiration condition, respectively. In accordance with the present invention, an anti-rotation device is cooperatively positioned between the pump chassis assembly and the drive member. This anti-rotation device substantially prevents rotational displacement of the drive member relative to the pump chassis assembly, about the screw rotational axis, during rotational motion of the lead screw shaft. Accordingly, any rotation of the drive member about the shaft rotational axis, resulting from the initial rotation of the lead screw shaft 23 (e.g., from the torque), will be counteracted.

Problems solved by technology

When multiple liquids are required for dispensing, however, such as two or more, additional equipment is required, which entails substantial pump costs.

Additionally, the need may arise for pumping liquids at different pressures due to dissimilar downstream restrictions and flow requirements.

In these situations, the common solution is to use distinctly separate pumps which also increases costs.

Images