Rotary axial peristaltic pumps and related methods
View Patent ↗Rotary axial peristaltic pumps, related methods and components. The rotary axial peristaltic pump generally comprises a platen having a platen surface, a tube positioned adjacent to the platen surface, cam that rotates about a rotational axis and has a cam surface that is spaced apart from the platen surface and a plurality of tube compressing fingers. The fingers move axially back and forth in sequence to sequentially compress segments or regions of the tube against the platen surface, thereby causing peristaltic movement of fluid through the tube. The fingers move back and forth on axes that are substantially parallel to the axis about which the cam rotates.
1. A pump finger/cam assembly for use in a finger-type peristaltic pump wherein a plurality of fingers sequentially compress and decompress a pump tube against a platen thereby causing peristaltic movement of fluid through the pump tube, said pump finger/cam assembly comprising:
a cam having a concaved race formed therein, said cam rotating about an axis of cam rotation;
a plurality of fingers, each finger defining an aperture and including: (i) a tube-compressing surface at one end, (ii) a roller at the other end, and (iii) a pin, each finger operable with a retraction apparatus, each retraction apparatus including a spring that includes a hooked end, the spring held in position by the pin, the hooked end of the spring (a) extending through the aperture defined in the finger and (b) configured to engage an aperture in the peristaltic pump, and wherein each retraction apparatus biases the finger toward the cam, said roller being rotatable about an axis of roller rotation; and
said roller riding rotatably within the race of the cam such that the axis of roller rotation is substantially perpendicular to the axis of cam rotation.
2. The assembly according to claim 1 wherein the race has a substantially arcuate wall and the roller is substantially spherical.
3. The assembly according to claim 1 wherein the race has a substantially V shaped wall and the roller contacts opposite sides of the substantially V shaped wall.
4. The assembly according to claim 1 wherein the race has a substantially tapered wall and the roller contacts the substantially tapered wall.
5. The assembly according to claim 1 wherein the race has a raised surface and the roller is configured to ride on said raised surface.
6. The assembly according to claim 1 wherein the cam surface includes a plurality of lobes.
7. The assembly according to claim 6 wherein each lobe of the cam comprises a wave in the cam surface, each such wave having a peak, the peak of each wave being closer to the platen surface than the remainder of the platen surface.
8. The assembly according to claim 1 wherein each retraction apparatus is further configured to retract the tube-compressing surface of the finger away from the tube after the finger has compressed the tube.
9. The assembly according to claim 1 wherein each retraction apparatus biases the finger such that the roller remains in contact with the race at all points of rotation of the cam.
10. The assembly according to claim 1 wherein the cam surface is located on a peripheral region of the cam.
11. The assembly according to claim 1 wherein each finger comprises a tube occlusion element that protrudes beyond the tube compressing surface, each occlusion element being configured to substantially occlude the lumen of the tube during a portion of the pumping cycle.
12. The assembly according to claim 11 wherein the tube-contacting surface has a first width and each occlusion element has a second width that is narrower than the first width.
13. The assembly according to claim 11 wherein each finger has a maximum point of travel where the tube occlusion element is as close as it comes to the platen, and wherein each tube occlusion element is spring biased so as to exert a controlled amount of compressive force on the tube when that finger is at or within a predetermined distance of its maximum point of travel.
14. The assembly according to claim 13 wherein a transverse slot is formed in each finger and each of the tube occlusion elements is slidably disposed within the respective transverse slot.
15. The assembly according to claim 14 wherein each finger includes a spring that urges the tube occlusion element to an extended position.