Pulsefree peristaltic pump and method of operating same

Claim 1

A peristaltic pump comprising: a tube provided with a flexible wall having an inlet for a fluid to be conveyed, an outlet for said fluid and an operating zone between said inlet and outlet, said operating zone including an arcuately curved upstream portion and an arcuately curved downstream portion; a first support rotatable about the center of curvature of said upstream portion; a second support rotatable codirectionally with said first support about the center of curvature of said downstream portion; leading impeller means mounted on said second support for intermittent engagement with said downstream portion for deforming the wall thereof to control the advance of said fluid toward said outlet in a series of recurrent operating cycles by obstructing said tube at a first point progressing in the flow direction; trailing impeller means mounted on said first support for intermittent engagement with said upstream portion for deforming the wall thereof to control the advance of said fluid toward said outlet by completely obstructing said tube at a second point progressing in the flow direction, the obstruction of the tube at said points coinciding during a confinement period of each operating cycle terminating with the unblocking of the tube at said first point, at least one of said impeller means being effective to block the tube at any time; drive means for rotating said supports at mutually related speeds; and pressure-control means effective in the flow-blocking position of said leading impeller means for developing between said first and second points a fluid pressure substantially equaling the pressure prevailing downstream of said first point during said period.

Claim 9

A method of delivering a continuous fluid flow substantially free from pulsations, comprising the steps of: feeding a working fluid into the inlet of an open-ended tube with a flexible wall; progressively deforming the tube wall at an upstream point and at a downstream point advancing toward the tube outlet, in a series of recurrent strokes, with simultaneous obstruction of the tube at said points during a confinement period of each stroke cycle whereby a discharge pressure of predetermined magnitude is developed in the fluid between said downstream point and said outlet, the tube being always obstructed at least at one of said points, said discharge pressure exceeding the supply pressure prevailing between said inlet and said downstream point; and adjusting the fluid pressure between said points to a level substantially equaling that of said discharge pressure with maintenance of the adjusted pressure during said confinement period until the unblocking of the tube at said downstream point.

Claim 10

A method of delivering a continuous fluid flow substantially free from pulsations, comprising the steps of: feeding a working fluid into the inlet of an open-ended tube with a flexible wall; progressively deforming the tube wall at an upstream point and at a downstream point advancing toward the tube outlet, in a series of recurrent strokes, with simultaneous obstruction of the tube at said points during a confinement period of each stroke cycle whereby a discharge pressure of predetermined magnitude is developed in the fluid between said downstream point and said outlet, the tube being always obstructed at least at one of said points, said discharge pressure exceeding the supply pressure prevailing between said inlet and said downstream point; and adjusting the fluid pressure between said points to a level substantially equaling that of said discharge pressure with maintenance of the adjusted pressure during said confinement period until the unblocking of the tube at said downstream point.