Proportioning pump

Abstract

A proportioning pump for automatic fluid analysis apparatus comprising a base having an open chamber formed in its top, a drive shaft supported in the open chamber, and a platen member that closes the top of the open chamber. A pair of roller cage assemblies each have primary bores in their end plates allowing them to be mounted on the drive shaft. The end plates are pinned to the drive shaft so that they rotate as one. Spaced outwardly a predetermined radius from the longitudinal axis of the primary bores are a plurality of secondary bores whose longitudinal axes describe circles in the laterally spaced end plates. Roller rods are journaled in the secondary bores. The outer perimeter of each of the roller rods describes an arc of a predetermined radius from the axis of the primary bore when the roller cage assembly is rotated about its longitudinal axis. The platen member has a bottom pressure surface having a predetermined concave transverse curvature which is positioned with respect to the roller cage assembly such that the spacing between the arc described by the outer surface of the roller rods and the pressure surface gradually decreases from a predetermined maximum to a predetermined minimum and then gradually increases back to a predetermined maximum. A plurality of fluid flow tubes pass in a direction transverse to the axis of the pump and are captured between the top of the roller cage assemblies and the bottom of the platen member.

Dependencies are inferred from the claim text.