Patent ID: 8337181

Claim:
An assembly for a rotary pump, the assembly comprising: a housing that comprises a side wall having an upper end and a lower end wherein a surface of the side wall defines in part a chamber having a longitudinal axis extending between the upper end to the lower end, a cross-sectional area at the upper end and a cross-sectional area at the lower end, and wherein the cross-sectional area at the upper end exceeds the cross-sectional area at the lower end; a shaft having a longitudinal axis aligned with the longitudinal axis of the chamber, wherein the shaft comprises a surface that defines annuli with respect to the surface of the side wall of the housing, and wherein, at each position along the aligned longitudinal axes, each of the annuli comprises a minimum radial distance and a maximum radial distance; and deformable rollers disposed between the surface of the shaft and the surface of the side wall of the housing, each of the deformable rollers having a longitudinal axis disposed at an angle to the aligned longitudinal axes of the chamber and the shaft.