System and method for improved flow uniformity in a peristaltic pump mechanism

Patent metadata

Field	Value
Publication number	US-10837436-B2
Application number	US-201514885832-A
Country	US
Kind code	B2
Filing date	Oct 16, 2015
Priority date	Dec 8, 2011
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

A pumping mechanism includes a plurality of peristaltic pumping actuators to compress adjacent portions of a first portion of an at least partially compressible pumping element having an inlet that is upstream of an outlet. The plurality of pumping actuators further reciprocate at a common drive frequency with a first phase offset between each adjacent pair of pumping actuators. The pumping mechanism also includes one compensation actuator to compress a second portion of the compressible pumping element disposed between the first portion and the outlet. The compensation actuator reciprocates at an optimal displacement and at a modulation frequency that is an integer multiple of the fundamental drive frequency and with a second phase offset between the compensation actuator and the adjacent pumping actuator.

First claim

What is claimed is:

1. A method, comprising:
peristaltically manipulating a first portion of an at least partially compressible pumping element having an inlet that is upstream of an outlet, the first portion disposed between the inlet and the outlet, to cause a fluid to flow out of the outlet at a first flow rate that varies periodically between a first maximum and a first minimum at a first frequency; and
manipulating a second portion of the at least partially compressible pumping element that is disposed between the first portion and the outlet at a second frequency that is a harmonic of the first frequency, to cause the fluid to flow out of the outlet at a second flow rate that varies periodically about zero, wherein a sum of the first and second flow rates has a second minimum larger than the first minimum, wherein:
peristaltically manipulating the first portion comprises actuating a plurality of pumping actuators coupled to a drive shaft,
manipulating the second portion comprises actuating a plurality of compensation actuators coupled to the drive shaft wherein each of the plurality of compensation actuators is actuated to have an independent displacement profile and has a shape configured to displace a same volume of the fluid as each of the plurality of pumping actuators; and
rotating at least two of the plurality of compensation actuators in phase.

2. The method of claim 1 , wherein:
there is a phase offset between the manipulating the first portion of the at least partially compressible pumping element and the manipulating the second portion of the at least partially compressible pumping element.

3. The method of claim 2 , wherein a phase offset between the first and second flow rates is in a range of 90°-270°.

4. The method of claim 3 , wherein the phase offset between the first and second flow rates is 180°.

5. The method of claim 2 , wherein the harmonic of the first frequency comprises at least one higher-order frequency that is an integer multiple of the first frequency.

6. The method of claim 5 , wherein the harmonic of the first frequency comprises a frequency that is twice the first frequency.

7. The method of claim 2 , wherein the harmonic of the first frequency comprises a frequency that is three times the first frequency.

8. The method of claim 1 , wherein the sum of the first and second flow rates at the outlet is greater than zero at all times while pumping the fluid.

9. The method of claim 1 , wherein:
actuating the plurality of pumping actuators comprises actuating the plurality of pumping actuators by rotating a plurality of pumping cams with the drive shaft; and
actuating the plurality of compensation actuators comprises actuating the plurality of compensation actuators by rotating a plurality of corresponding compensation cams with the drive shaft.

10. The method of claim 9 , wherein rotating the plurality of corresponding compensation cams with the drive shaft comprises rotating the plurality of corresponding compensation cams out of phase and at a common frequency with the plurality of pumping actuators.

11. The method of claim 1 , wherein actuating the plurality of compensation actuators comprises actuating the plurality of compensation actuators with a first lift that is smaller than a second lift of any of the plurality of pumping actuators.

12. The method of claim 11 , wherein actuating the plurality of compensation actuators further comprises actuating two compensation actuators with a lift.

13. The method of claim 11 , wherein actuating the plurality of compensation actuators further comprises:
actuating a first compensation actuator with the first lift; and
actuating a second compensation actuator with a second lift that is smaller than the first lift.

14. The method of claim 1 , further comprising rotating the drive shaft at a varying rotational speed, wherein a full cycle of the drive shaft comprises one or more variation periods of the varying rotational speed.

15. The method of claim 1 , further comprising rotating the drive shaft at a varying rotational speed with a variable speed transmission coupling a cam wheel attached to the drive shaft with a circular drive wheel, the cam wheel having an asymmetric shape.

16. The method of claim 1 , wherein manipulating the second portion comprises using a gear linkage coupled to the plurality of compensation actuators.

17. The method of claim 1 , wherein manipulating the first portion comprises controlling the drive shaft with a first motor, and manipulating the second portion comprises controlling the plurality of compensation actuators with a second motor.

18. A pumping mechanism comprising:
a peristaltic pumping mechanism having an inlet and an outlet, the pumping mechanism configured to receive a fluid through the inlet and provide an output flow of the fluid through the outlet at an output flow rate that varies periodically over time about a nominal flow rate, wherein the peristaltic pumping mechanism comprises a first portion comprising a plurality of pumping actuators coupled to a drive shaft, and a second portion comprising a plurality of compensation actuators coupled to the drive shaft, the plurality of compensation actuators configured to actuate independently of the plurality of pumping actuators in the first portion, and having a same shape as the plurality of pumping actuators in the first portion, wherein the plurality of compensation actuators have in phase rotation of at least two of the plurality of compensation actuators; and
a variable volume having an inlet fluidically coupled to the outlet of the pumping mechanism and an outlet, wherein the variable volume is configured to vary synchronously with a periodic variation of the output flow.

19. The pumping mechanism of claim 18 , wherein:
a variable volume increases during at least a portion of a time when the output flow rate through the outlet of the pumping mechanism is greater than the nominal flow rate; and
the variable volume decreases during at least a portion of the time when the output flow rate through the outlet of the pumping mechanism is less than the nominal flow rate.

20. The pumping mechanism of claim 19 , wherein the plurality of compensation actuators are configured to control the variable volume.

21. A method of pumping a fluid through an intravenous (IV) set having an outlet, the method comprising:
rotating a drive shaft coupled to a drive motor by rotating the drive motor with a variable speed such that the rotation of the drive motor comprises a fundamental frequency and a modulation frequency that is an integer multiple of the fundamental frequency and the fundamental frequency is determined by an inverse of a time period required for the drive shaft to complete one 360° rotation;
peristaltically manipulating adjacent sections of a first portion of the IV set when the drive shaft is rotated using a plurality of pumping actuators respectively coupled to a plurality of pumping cams, the plurality of pumping cams being disposed in a row along the drive shaft and coupled to the drive shaft, the plurality of pumping cams having common profiles and arranged as offset cams with common rotational offsets between each pair of adjacent pumping cams, the plurality of pumping cams comprising a last pumping cam;
selectively compressing a section of a second portion of the IV set that is disposed between the first portion and the outlet using a plurality of compensation actuators coupled to a respective plurality of compensation

Assignees

• Carefusion 303 Inc

Inventors

• Butterfield Robert D
• Abal Daniel

Classifications

• F04B49/06 Primary

  Control using electricity (regulating by means of floats actuating electric switches F04B49/04) · CPC title

• F04B43/14

  having plate-like flexible members · CPC title

• F04B43/09

  Pumps having electric drive · CPC title

• F04B43/082 Primary

  the tubular flexible member being pressed against a wall by a number of elements, each having an alternating movement in a direction perpendicular to the axes of the tubular member and each having its own driving mechanism · CPC title

• F04B9/042

  the means being cams · CPC title