Patent Application
20080101968
This invention relates generally to pumps and related methods and more specifically to peristaltic pumps and methods for pumping fluids that are useful in a variety of medical and non-medical applications.
Peristaltic pumps are devices that transfer fluid through one or more elongate, at least partially flexible, tube(s) by compressing each tube in a peristaltic manner. Fluid transport through the tube is effectuated by moving a region of compression along the length of the tube. Such movement of the region of compression is typically achieved by way of one or more rollers or reciprocating pushers that progressively move an area of compression along the length of the tubing to thereby pump fluid through the tubing in a peristaltic motion. Such pumps are often used in medical applications including intravenous or subcutaneous infusion, withdrawal of fluids as in wound drainage systems as well as various laboratory instruments and industrial applications, such as industrial applications where toxic or corrosive fluids are pumped.
Typical linear peristaltic pumps include those described in U.S. Pat. No. 2,877,714 (Sorg et al.), U.S. Pat. No. 4,671,792 (Borsannyi), U.S. Pat. No. 4,893,991 (Hemingway et al.) and U.S. Pat. No. 4,728,265 (Canon), the entire disclosures of which are expressly incorporated herein by reference. In general, these pumps require a drive shaft that is parallel to a resilient tube and a plurality of cams along the drive shaft to move pushers toward and away from the tube.
Rotary peristaltic pumps generally dispose a resilient tube along a circular path, with a number of rollers mounted around the circumference of a circular rotor-sequentially rolling along the tube to occlude the tube and force liquid through the tube. Typical of such pumps are those disclosed in U.S. Pat. No. 4,886,431 (Soderquist et al.) and U.S. Pat. No. 3,172,367 (King), the entire disclosures of which are expressly incorporated herein by reference. These pumps often have relatively low efficiency and impose high shear and tension stresses on the tube causing internal tube wall erosion or spallation. The tube may eventually be permanently deformed so that the tube becomes flattened into a more oval shape and carries less liquid.
The prior art has also included another type of peristaltic pump wherein a tube is arranged along a circular path and a cylindrical cam that rotates eccentrically is used to sequentially move a plurality of blunt pushers or fingers to sequentially compress regions of the tube from one end of the path to another and of the path. Examples of such pumps are described in German Patent No. 2,152,352 (Goner) and Italian Patent No. 582,797 (Tubospir), the entire disclosures of which are expressly incorporated herein by reference. In general, these “finger” type peristaltic pumps tend to be less complex than linear peristaltic pumps. However, the pressure exerted by the blunt fingers on the tubing can reduce the usable life of the tubing and can, in at least some cases, cause internal tube wall erosion or spallation resulting in possible loss of particulate matter from the tube wall into the fluid stream. Also, in at least some cases, tubes with different wall thicknesses may not be accommodated by these pumps, since with thinner than standard tubes the fingers will not properly occlude the tube and with thicker than standard tubes the tube will close prematurely and be subject to excessive compression, requiring higher cam drive power and causing excessive wear on the cam and tube.
In many applications of peristaltic pumps, in particular medical applications, it is important to promptly detect when the pump ceases to operate due to an occlusion in the pump tube either before or after the pump. In other applications, it is equally important to monitor the pressure in the tubing. An input occlusion occurring in the tube leading to the pump will cause the tube to collapse due to the fluid being sucked from the input side and pushed out the output side. An output occlusion occurring in the tube leading away from the pump will continue to push liquid into the output tube, inflating the tube and possibly causing it to burst. In either case, fluid flow to the end use is stopped or reduced.
One type of peristaltic pump that is especially effective is the curvilinear peristaltic pump described in U.S. Pat. No. 5,791,881 (Moubayed et al.), the entire disclosure of which is incorporated herein by reference. In the pump described in U.S. Pat. No. 5,791,881, a resilient tube is disposed against a generally circular platen and a rotating cam member sequentially and radially moves a plurality of fingers such that the fingers compress the tube and force the fluid through the tube in a peristaltic fashion. In this curvilinear peristaltic pump of the prior art, the cam drives the pump fingers in a radial direction. Because the pump fingers extend in a radial direction from the curved cam surface, the pump must be large enough (in the radial direction) to accommodate the outer radial length of the cam, the height of the pump fingers and the thickness of the concave curved platen.
There remains a need in the art for the development of new peristaltic pumps that provide advantages and/or useful improvements or differences over those of the prior art.
Accordingly, the present invention provides peristaltic pump devices (sometimes referred to herein as “rotary axial peristaltic pumps”) and methods which provide advantages and/or useful improvements or differences over the peristaltic pumps of the prior art. In at least some embodiments of the present invention, there are provided rotary axial peristaltic pumps that provide smooth fluid delivery, low drive torque power requirements, and/or less complexity than the conventional peristaltic pumps of the prior art.
In accordance with one embodiment, a peristaltic pump device is provided which generally comprises a platen assembly including a platen surface, a cam having a rotational axis and a cam surface spaced apart from the platen surface. In addition, the device comprises a plurality of fingers having a first portion in cooperative engagement with the cam surface and a second portion adjacent the platen surface and structured to engage and compress a tubing disposed along the platen surface. The device may further include a housing containing the cam and fingers.
Further in accordance with this invention, the platen assembly, cam and fingers may be operatively configured such that, when the cam is rotated about its rotational axis, the second portions of the fingers will reciprocate in a direction that is substantially parallel to the rotational axis of the cam, such that when a fluid filled compressible tubing is disposed along the platen surface, the reciprocating motion of the second portions of the fingers will effect pumping of the fluid through the tubing.
Still further in accordance with this invention, in some embodiments, the platen may comprise a substantially planar surface that is configured to receive a portion of compressible tubing parallel thereto. In some embodiments, the platen assembly may include one or more tube holding member(s) (e.g., clips, ribs, notches, magnets, grooves, recesses, etc.) that hold or retain the compressible tubing in a desire position or configuration between the platen surface and the second portions of the fingers. For example, in some embodiments, the tube holding member(s) may comprise a plurality of spaced apart rib members, extending from the platen surface and including features, for example, cut out regions, for receiving and securing a tubing in an appropriate position along the platen surface.
Still further in accordance with this invention, in some embodiments, the platen assembly may comprise a door that is hingedly or pivotally connected to the housing, wherein such door includes the platen surface on an interior surface thereof. In embodiments that include such door, the door may be structured to facilitate installation and removal of the tubing, and maintenance of the device by allowing easy access to the tubing carrier as well as the fingers and/or other components of the system.
Still further in accordance with this invention, the fingers of the pump may reciprocate back and forth on longitudinal axes that are generally perpendicular to the cam surface and generally parallel to an axis of rotation about which the cam rotates. Generally, as the cam assembly is rotated about the axis of rotation, elevations or lobes on the cam may cause the fingers to move in a direction substantially parallel to the cam rotational axis. More specifically, the cam surface may be described as including a path, or a cam race on which the first portions of the fingers ride as the cam moves. The fingers may be aligned along a path defined by the cam race. The cam race is preferably located on a peripheral region of the cam, such cam race having one or more race surface(s) upon which the fingers ride. An axial plane may be projectable through the race surface(s), such axial plane being substantially perpendicular to the axis of rotation about which the cam rotates. The cam race includes elevated regions or lobes which, when the cam is rotated about the rotational axis, cause the second portions of the fingers to move back and forth along their longitudinal axes, thereby sequentially compressing and decompressing the tubing to effect pumping of fluid through the tubing.
Still further in accordance with this invention, in some embodiments, the first ends of the fingers may include moving members, for example rollers mounted on or within first ends of the fingers. These moving members (e.g., rollers) may contact and roll or otherwise move along the cam race as the cam surface moves along the rotational path. In some embodiments, these rollers may be substantially spherical. Also, in some embodiments, the cam surface may include a substantially concave race. Such concave race may be configured such that the radius of the race is larger than the radius of the rollers. Thus, in effect, each of the rollers will contact the cam race at a “point” or limited area of contact. In other embodiments, the race may comprise a groove or depression such that each of the rollers will contact opposing locations on the opposite side walls of the groove or depression. In still other embodiments, the race may comprise a tapered groove and the rollers may be correspondingly tapered so as to ride on a tapered wall of the race. In still other embodiments, the race may comprise a raised area or rail and the rollers may be correspondingly configured so as to ride on such raised area or rail. In still other embodiments, the race may comprise a wavy or curved cam surface and the rollers may be maintained in positions that cause the rollers to ride on such wavy or curved surface.
Still further in accordance with this invention, in some embodiments, the pump may incorporate spring(s) or other biasing apparatus for actively retracting the fingers after they have compressed the tubing as intended, without requiring the fingers to be linked to the cam in such a way as to cause the cam to actively pull the fingers away from the tubing. More specifically, the fingers may interact with spring(s) or other biasing apparatus that cause retraction of the second end of each finger in a direction away from the platen surface after that finger has caused the desired compression of the tubing. Additionally or alternatively, the fingers may interact with spring(s) or other biasing apparatus that substantially maintain the fingers in operative engagement with the cam surface. Such spring(s) or other biasing apparatus may be structured to allow for a more precise degree of control over the operation of the fingers, and more precise control over pumping overall, relative to prior art devices which rely on resiliency or springiness of the tubing to cause retraction of pump fingers and/or which require the fingers to be coupled to the cam such that the cam not only pushes each finger to compress the tubing but also pulls each finger to cause it to retract away from the tubing.
Still further in accordance with this invention, in some embodiments, tip members may be located on the ends of some or all of the pump fingers. Such tip members may be spring biased or otherwise biased to provide a controlled amount of compressive force on the tubing such that the lumen of the tubing will be fully occluded or “pinched off” when the finger reaches its point of maximum travel but the compressive force on the tubing will not be so strong as to cause unnecessary stress or wear on the tubing. In at least some embodiments, the tip members will be narrower than the width of the compression surface of the finger. Such tip members may be shaped to provide for a discrete occlusion zone that extends transversely across the tubing when the finger reaches its point of maximum travel.
Still further in accordance with this invention, the pump device may optionally include a strain gauge transducer or other apparatus that provides an indication of the degree or amount of deflection, expansion or contraction of the tubing as fluid is being pumped through the tubing.
These and other aspects and advantages of the present invention are apparent in the following detailed description and claims, particularly when considered in conjunction with the following drawings in which like parts are identified by like reference numerals.
The following detailed description and the accompanying drawings are intended to describe some, but not necessarily all, examples or embodiments of the invention. The contents of this detailed description and the accompanying drawings are not necessarily all-inclusive and do not limit the scope of the invention in any way.
The device 10 shown in
The device 10 shown in
Referring now specifically to
The cam 30 is rotatable about the axis of rotation AR by suitable means such as a motor driven gear mechanism 56 (shown in
As shown in dashed lines on
In some embodiments, the tubing may be pre-mounted on or in the cassette 60, thereby eliminating the need for manual handling and mounting of the tubing element 50 within the pump device 10. Additionally or alternatively, the shape of the notches 65, or other cut away regions through which the tubing element 50 passes, may be of generally triangular shape or may be otherwise shaped so as to assist or facilitate rebounding of the tubing element 50 to its fully, or near fully, expanded, non-compressed shape after it has been compressed by each finger 44. Such notches 65 or other suitable tube-constraining or tube-contacting structures provide partial compression or resistance to expansion of the tubing element 50 in a direction that is generally perpendicular to the direction in which the finger 44 compresses the tubing element 50, thereby countering the compressive effect on the tubing element 50 and facilitating rapid re-expansion of the tubing element 50 as the finger 44 is withdrawn away from the tubing element 50.
Additionally or alternatively, in some embodiments, the cassette 60 may include a tag, barcode, sensor, switch, triggering mechanism, identifying protrusion(s), machine readable element(s) or other apparatus/material that will enable a sensing (e.g., detecting) component of the pump device 10 (e.g., a sensor that is in communication with a computer, controller or other processor) to identify a particular cassette 60, or a particular size/type of cassette 60, or to identify the presence or absence of the cassette 60 and, optionally, to disable the pump device 10 or provide an alarm (e.g., audible alarm, light, etc) or other signal when the cassette 60 is absent, improperly positioned or of an incorrect size/type, etc.
As seen in
In the closed position, such as shown in
As illustrated in
The first portions 46 of the fingers 44 may include a moving element, for example a roller 80 which rides upon a surface of the cam 30. In some embodiments, a race 32, such as a groove, depression, track, etc., is formed in the cam 30 and the rollers 80 ride within such race 32. In the example shown, the rollers are secured to the fingers 44 by axles 82 about which the rollers 80 rotate. Alternatively, as in embodiments where the rollers 80 are substantially spherical, the rollers may be disposed and retained within recesses on the ends of the fingers 44 without being centered on an axle, so as to freely roll in all directions in a fashion similar to the ball of a ballpoint pen.
In the embodiments shown in
The second portion 48 of each finger 44 includes a head portion 84 which at least partially extends beyond the housing front surface 62 and contacts tubing 50 held in the cassette tubing carrier 60.
In order to more clearly understand various aspect of the present invention, reference is made to
The pump finger 44, in accordance with one aspect of the invention, may include a tube occluder surface 88, such as a leading edge or tip member, that fully compresses the tube 50 such that the lumen of the tube 50 becomes fully closed or pinched off when the finger 44 is at or beyond a desired amount of forward advancement (e.g., when the finger 44 is within a certain distance of its maximum forward travel). For example, in the embodiment shown, finger 44 incorporates a transverse slot 90 through which a spring-biased occlusion element 92 extends slightly beyond a compression surface 94 of the head portion 84 of the finger 44. Occlusion element 92 is shown substantially centrally located within head portion 82 but other locations may also be suitable. For example, in some embodiments the occlusion elements 92 may be located off-center, or near or at peripheral regions or ends of the compression surfaces 94. Occlusion element spring 96 functions to bias the occlusion element 92 to an extended position. Extension of the occlusion element 92 may be limited by occlusion element guide pins 102 disposed in or associated with apertures 104. In the example shown in the drawings, the occlusion element 92 is positioned midway between opposite ends of the compression surface 94 such that on each finger 44 portions of the compression surface 94 are located on either side of the occlusion element 92. It will be appreciated, however, that in some embodiments the occlusion elements 92 may be positioned at locations other than midway between the ends of the compression surface 94.
Turning to
Referring back now to
The pump device 10 operates in the following manner. Referring to
As the cam 30 rotates moving the left cam lobe to the right, the second left pump finger further extends to compress and occlude the tubing above it while at the same time the last finger retracts and removes the tubing occlusion above it. Fluid in the tube 50 now starts to flow to the right past the last pump finger. In addition, fluid from the inlet side of the tubing 50 begins to fill the tubing section behind (from the left) of the second left pump finger. As the left cam lobe continues to move to the right, subsequent pumping fingers progressively continue to compress and occlude the tubing above them thus causing the fluid in the tubing to flow to the right and fill from the left. In as much as the cam has a plurality of cam lobes, when the left lobe finally arrives under the last pump finger (right most), another cam lobe arrives under the first pump finger capturing a new volume of fluid between the first and last pump fingers 44.
Rollers 80 or other movable members on the fingers 44 may roll, rotate ride or otherwise ride or track through a cam surface 32 that comprises a race, such as a groove or depression. The shape of the roller 80 or other movable element may correspond to the shape of the cam surface race 32 to provide for firm tracking and minimal wear of the rollers 44.
Operation of an individual fingers 44 of the pump device 10 may be more clearly understood with reference to
As shown in
Optionally, as shown in
Referring to
It is to be appreciated that the invention has been described hereabove with reference to certain examples or embodiments of the invention but that various additions, deletions, alterations and modifications may be made to those examples and embodiments without departing from the intended spirit and scope of the invention. For example, any element or attribute of one embodiment or example may be incorporated into or used with another embodiment or example, unless to do so would render the embodiment or example unsuitable for its intended use. Also, where the steps of a method or process are described, listed or claimed in a particular order, such steps may be performed in any other order unless to do so would render the embodiment or example un-novel, obvious to a person of ordinary skill in the relevant art or unsuitable for its intended use. All reasonable additions, deletions, modifications and alterations are to be considered equivalents of the described examples and embodiments and are to be included within the scope of the following claims.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11212931 | Aug 2005 | US |
| Child | 11437274 | US |
