Peristaltic Pump With Stacked Components

Abstract

The roller member and/or the arcuate support member for the tubes of a peristaltic pump are stacked to accommodate a number of tubes. The rotor is stacked from disks having rollers along one surface so that the disks may be assembled in back-to-back relationship to accommodate large-diameter flexible tubing or in a series relationship to accommodate tubing of smaller diameter. The support is similarly made up of flanged members which may be stacked back to back or in series (face-to-back).

Description

FIELD OF THE INVENTION

My present invention relates to peristaltic pumps and, more particularly, to peristaltic pumps operating with a number of tubes simultaneously and using a roller rotor or head.

BACKGROUND OF THE INVENTION

A common type of peristaltic type has a rotary head (rotor, barrel or drum) provided with an annular array of angularly equispaced rollers engageable with a flexible-wall tube held along a concave surface constituting a support or pressure member.

The rollers successively and progressively collapse the walls of the tube and thereby force liquid to move along the tube in the direction of rotation of the head. The peristaltic pump has some significant advantages. For example, the liquid to be displaced never comes into contact with moving parts of the pump so that the liquid cannot contaminate the pump or be contaminated thereby. To clean the pump, one may simply remove or replace the flexible-wall tubing. Sterility of the liquid can be maintained since the liquid system at least within the pump is closed and the liquid displacement takes place only by peristaltic action applied to the tube.

The feed rate is determined by the rotary speed of the head which is commonly connected to a variable speed motor, and by the caliber or bore-size of the tubing. When, for a given motor range, it is desired to increase the volume flow rate of the liquid, a tube of larger bore or caliber may be substituted. Conversely when it is desired to reduce the volume flow rate for a given motor speed, one merely makes use of a smaller-diameter tube.

However, conventional peristaltic pumps have various disadvantages. For example, there is the problem of creep of the tube when the latter is not held snugly against the support. Secondly, conventional systems operating on more than one tube must provide means for holding them apart so that the tubes do not interfere with one another, such means however may serve to restrict the ability of the pump to accommodate tubes of other sizes. Also, conventional roller heads and supporting members are relatively complex and expensive, are difficult to machine and cannot be replaced at low cost.

OBJECTS OF THE INVENTION

It is the principal object of the present invention to provide a simplified peristaltic-pump structure which avoids the aforementioned disadvantages while retaining the advantages of a conventional peristaltic pump.

It is another object of this invention to provide a peristaltic pump which may be rapidly adjusted to receive tubing of various sizes and, moreover, is capable of operating therewith without increasing the danger of tubing deterioration or decreasing pump efficiency.

It is also an object of this invention to provide a peristaltic pump, especially a rotary head therefor, which is capable of reducing or eliminating creep of the tubing.

It is an object of the invention, moreover, to provide a head assembly and support structure for a peristaltic pump of increased versatility and improved efficiency.

SUMMARY OF THE INVENTION

These objects and others which will become apparent hereinafter are attained, in accordance with one aspect of the present invention, by a revolutionary modification of the rotary head structure of a peristaltic pump.

More particularly, I have found that many of the disadvantages of earlier systems can be removed and a more efficient rotatable head for a peristaltic pump can be produced, when the latter is stacked from a plurality of readily manufactured, mass-produced and identical rotor elements each consisting of a disk provided with an annular array of angularly equispaced rollers and mounted upon a common shaft, the shafts and the disks being provided with key means enabling alignment of the disks so that either the reverse or the obverse side may face each side of an adjacent disk.

Consequently, the disks may be stacked in back-to-back relationship, also referred to herein as parallel stacking, or in face-to-back or head-to-tail relationship, also described as series stacking. In the parallel-stacked relationship, the disks are separated by twice the height of the rollers and a large-bore tube can be accommodated between the confronting surfaces for engagement by the rollers spanning same. When, however, the series stacking is provided, each roller spans the space between the obverse surface of its disk and the rear or reverse surface of an adjoining disk so that small-diameter tubing may be accommodated.

According to a more specific feature of this invention, each of the rotating-head disks may be molded from a synthetic resin integrally with the roller-journaling pins or may receive the pins as separate elements, each of the pins carrying a respective roller, preferably via a bearing. The pins are angularly equispaced about the periphery of the disk but inwardly of the edge thereof and the disk may have a hub portion provided with keying means, e.g., a flat co-operating with a flat one the drive shaft. Similarly, each pressure-bar segment may be molded from a synthetic resin and may be generally of crescent shape or yoke shape, with ears at each end so that each bar may be used in two positions as rotated through 180.degree. about an axis of symmetry of the bar in the plane thereof. A hinge pin swingably connects all of the pressure bars together and the pressure bars may be provided with individual swivel clamps.

According to another aspect of the invention, wear of the rubber tubing is reduced and creep is prevented by interposing between each section of tubing held against the pressure bar and the corresponding arc of the rotating head, a stationary or anchored band of synthetic resin material of high flexibility. Since the encircling band does not move with the disk, the rollers contact the stationary surface of the synthetic-resin band or strip which does not move significantly with respect to the tubing. Hence there is no tendency for the tubing to creep nor is there any substantial wear of the tubing resulting from contact with metal surfaces. The flexible strip may be nylon or the like and is in direct contact with the rollers and the tubing. The tubing itself does not have to be anchored and thus can be changed rapidly. The nylon strip has been found to prevent stretching and creeping as noted earlier and thus acts to prolong the life of the tube indefinitely.

DESCRIPTION OF THE DRAWING

The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing, in which:

FIG. 1 is a side-elevational view of a rotating segment, according to the present invention, of a roller head;

FIG. 2 is a plan view thereof;

FIG. 3 is a vertical elevational view of the rotating members in FIGS. 1 and 2 in series assembly to form a roller head for a peristaltic pump;

FIG. 4 is a lateral elevational view of a pressure-bar segment according to the present invention;

FIG. 5 is a plan view thereof;

FIG. 6 shows the stacked pressure-bar segments for a four-tube peristaltic pump using the head of FIG. 3;

FIG. 7 is a view similar to FIG. 3 but shows the stacking arrangement of the head as used for a tube of twice the diameter of the tube used with the head of FIG. 3;

FIG. 8 shows the parallel stacking of the pressure bar segments of FIGS. 4 and 5;

FIG. 9 is a perspective view illustrating other features of the invention;

FIG. 10 is a perspective view of a strip holder according to the present invention;

FIG. 11 is a detailed view thereof from above;

FIG. 12 is a plane view of a device for controlling the pumping action; and

FIG. 13 is a view taken in the direction of arrow XIII in FIG. 12.

SPECIFIC DESCRIPTION

In FIGS. 1 and 2, I show the basic element of a rotating head for a peristaltic pump according to the present invention The rotating head segment 1 comprises a molded synthetic-resin or corrosion-resistant metal disk 2 of a diameter 2R and a flat (planar) configuration. The disk is circular and is provided at angularly equispaced locations around its periphery with roller pins 3 having an axial height H and molded integrally with disk 2 or imbedded or fitted therein. At the center of the disk, I provide a metal insert 4 which is formed with an opening 5 chordally truncated at 6 to constitute a noncircular configuration (flat). The opening 5 is designed to receive a shaft 7 having a flat 8 designed to prevent relative rotation of the shaft and the disk when the latter is stacked thereon. As represented in dot-dash line 9 in FIG. 2, a roller (e.g. provided with ball bearings) is rotatably mounted on each of the pins when the stack is assembled.

In FIG. 3, I have shown a so-called series stack of the disks in which four such disks 10, 11, 12 and 13 are mounted upon a boss 14 of the base plate 15 of the peristaltic pump in which the shaft 7 is journaled. The shaft 7 is driven by a variable speed motor diagrammatically represented at 16. It will be apparent that the space S between the disks 10 and 11, between the disks 11 and 12, between the disks 12 and 13 and between the disks 13 and a cover plate 17 is equal to the height H of the respective rollers which are mounted upon the pins 3 mentioned earlier. The rollers 9 can be seen in FIG. 3. Hence between each pair of disks there is provided a channel 18 adapted to accommodate a small-diameter rubber or synthetic-resin tube. Thus any number of disks may be stacked to provide a corresponding number of channels or half that number of wider channels.

In FIGS. 4 and 5, I have shown the pressure-bar segments 20 which are stacked to co-operate with the rotating head 19 of FIG. 3. Each of these segments has a semicircular crescent-shaped central portion 21 defined by a ledge 22 and terminating at outwardly extending bifurcated ears 23 and 24. At either end of the crescent there is provided a bore 25 or 26 adapted to receive a hinge pin as shown at 27 in FIG. 6, when the pressure bars are stacked. The ledge 22 ends in an arcuate shoulder 28 adapted to clear the disk portions 2 of the disks of the rotating head when the system is assembled and hence has a radius of curvature R + .DELTA.r as shown in FIG. 5. However, the ledge 21, which is designed to hold the tubing against the rollers, has a radius of curvature R - .DELTA.r.sup.1.

When the pressure-bar segments are stacked (FIG. 6), the underside 29 of each of the pressure bars 31, 32 and 33 abuts directly the upper surface 34 of the underlying pressure bar 30, 31 and 32, respectively. Between each pair of pressure bars there is defined in crescent-shaped recess 35, 36 and 37 into which the edge of the disks 10-13 may pass without obstruction.

From FIG. 9, it will be apparent that the head 19 is juxtaposed over a portion of its periphery with the pressure bar 40 made up of the segments 30, 31, 32 and 33 as stacked upon the hinge pin (pintle) 27. Just as each disk 11, 12 or 13 is received in a recess 35, 36 or 37 between the pressure-bar segments, each of the ledges 21 of the pressure-bar segments is received between a pair of disks. Respective sections of resilient tubing 41, 42 and 43 are received within the channels 18 between the disks and engage the ledges 21. Between the tubing and the rotating head 19, there are provided nylon strips 61 which are anchored at 50 against rotation and are sufficiently flexible to permit peristaltic compression of the tubing by the rollers. The hinge pin 27 is, of course, anchored to the support plate and the swivel clamp illustrated at 51 may be provided for each of the pressure-bar segments. These swivel clamps comprise eyes 52 mounted upon a rod 53 and rotatable thereon to bring a shank 54 into the notch 55 formed by the bifurcated ear. The shank 54 is threaded to receive a clamping nut 56 which may adjust the pressure applied to the respective tube. When the same diameter tube is used at all of the roller arrays, I may use a single swivel clamp and connect the adjustable ends of the pressure-bar segments by a rod 60 as illustrated in dot-dash lines in FIG. 9.

In FIGS. 7 and 8, I show the system as it is assembled in parallel or back-to-back relationship. The disk 10 with its array of rollers 9 faces the disk 11 while the disk 12 is back-to-back with disk 11 and faces disk 13. In other words, alternate disks are rotated through 180.degree. about a diameter thereof and are disposed mirror-symmetrically in pairs in the drum 69 of FIG. 7. Hence the disks 2 are mirror-symmetrical with respect to a plane P' of symmetry perpendicular to the disk and through the key formation 6 and the axis of the disk and the pins 3 are disposed mirror-symmetrically with respect to a plane of symmetry P" perpendicular to plane P' and through the center of the disk, the reversal of alternate disks for the parallel stacking of FIG. 7 brings the rollers of the disk pairs automatically into axial alignment. The rollers thus span a total width W to accommodate large-diameter tubes. Since large-diameter tubes require wider pressure-bar segments, the pressure bar 70 of FIG. 8 is used. In this parallel-stacked system, the underside 29 of one segment 30 abuts the underside of the next overlying segment 31 which, in turn, is a face-to-face relationship with a pressure-bar segment 32, the latter being back-to-back with segment 33. The total width w of the ledges may be slightly smaller than W so as to be accommodated with clearance between the disk members. Here again, a bar 60 may be used to couple the adjustable ends of the pressure-bar segments for joint movement.

An important feature of my present invention is the fact that the use of nylon strips, i.e., flexible but substantially nonstretchable strips, between the rollers and the elastomeric tubes, prevents or severely limits stretching of the pump tubing. Stretching of pump tubing has long been a substantial problem in the peristaltic-pump art. Since the peristaltic pump has a displacement which depends upon the rate of peristaltic counter-action and expansion of the tube and the internal diameter thereof, distension of the tube to change its caliber or bore diameter, results in a modification of the pumping rate or volume in an uncontrolled manner. The nylon strips of the present invention eliminate such stretching.

In FIGS. 10 and 11, I have shown a particularly convenient nylon strip holder which may be used in conjunction with the roller and backing system of FIG. 9 or any of the Figures previously discussed. This holder comprises a generally U-shaped bracket 101 which is mounted on the support plate of the pump and has a base 102 extending in the direction of the roller drum 103. The upstanding arms 104 and 105 of this bracket have flanks 106 and 107 converging inwardly and rearwardly toward a pair of parallel flanks 108 and 109 of a clamping block 110. The latter is secured to the base 102 and to the support plate 15 of the pump. Along the rear surface of the block 110, I attach, via screws 111, a comb-shaped leaf spring 112 having a central web 113 and outwardly extending arrays of fingers 114 reaching toward the arms 104 and 105, respectively, and spaced from the parallel flanks 115 and 116 thereof by a distance which is less than the distance d between flanks 116 and 109 and flanks 115 and 108. When the nylon strip 61 is drawn through the gap 117 or 118 between these pairs of flanks, the fingers 114 are merely deflected rearwardly (FIG. 11) and clamp the nylon strip. To release the nylon strip, it is merely necessary to deflect each finger 114 outwardly and withdraw the strip. A can be seen in FIG. 10, the fingers correspond in width to the strips which are received in the roller channels for small-diameter tubing. When, however, a channel of double width is created, (FIG. 7) a wider nylon strip such as that shown at 61' is used and is gripped by a pair of fingers 114. The member 112 is composed of spring stainless steel while members 110 and 102 may be die cast from a metal or composed of a synthetic resin.

Another feature of the present invention resides in the use of the pivotal backing or pressure bar members to control the pumping action or select the pumping tubes which are to be affected. In accordance with these principles, each of the pressure-bar segments 130 is swingably mounted on the pivot 127 as noted previously, the pressure-bar segments 130 being of the type illustrated in FIGS. 4 to 6 and 8. However, instead of clamping devices as shown at 51, the free ends of each pressure bar 130 are connected by a screw 131 and a milled nut 132 to a lever 133 individual to that pressure bar. In the position of the lever 133 illustrated in FIG. 12, the screw 132 may be rotated to establish the desired pumping pressure upon the tube 129 which is received in the channel between the pumping head 128 and the pressure bar 130. In this embodiment, nylon strips (not shown) are also used.

The lever 133 is fulcrumed at 134 to the pump support (e.g. , base 15) and is connected at its other end to a toggle linkage 135. A solenoid 136 has a plunger 137 spring biased in the direction of arrow 138 and, therefore, normally holds the pressure-bar segment array from its tube and prevents pumping operation. The toggle 135 comprises a pair of articulated arms 139, 140 which are connected at their hinge 141 to the plunger 137 of the solenoid. Consequently, when the plunger is retracted, the pressure bar segment 130 is swung in the clockwise sense and the tube 129 is engaged. Pumping therefore commences.

To prevent backflow of liquid through the tube, I provide a pinch clamp which is actuated by the solenoid. The pinch clamp comprises a channel 142 through which the tube 129 extends, the open side of the channel being provided with a finger 143 hinged at 144 to the channel and provided with a projection 145 which pinches the tubing when the free end 146 of the finger is shifted by the toggle.

The solenoids 136 can be controlled by individual or collective timers 147 to program the supply of liquid and block such supply as may be required.

Claims

I claim:

1. In a peristaltic pump having a rotatable head adapted to peristaltically compress elastic tubing against a pressure member, the improvement wherein said head comprises a plurality of axially stacked substantially identical rotating segments, each comprising a substantially circular disk and an array of rollers angularly equispaced about said disk and rotatable about respective axes, parallel to the axis of rotation of said head, said rollers of each disk being located along one side thereof, and keying means for positioning said disks selectively with the roller arrays of adjoining disks in contact and in an axially aligned relationship to define relatively wide tube-receiving channels between the disk and with nonroller sides in contact with the roller arrays of adjoining disks defining relatively narrow tube-receiving channels.

2. The improvement defined in claim 1 wherein said pressure member comprises a stack of substantially identical pressure bars of crescent configuration, each having a recess adapted to accommodate a respective one of said disks and a ledge extending inwardly toward said rollers whereby the side along which the ledge lies constitutes its back and the other side of each crescent bar is its face, and means for positioning said pressure bars selectively in face-to-face relationship when said head is formed with said relatively wide tubes receiving channels and a face-to-back relation when said head is formed with said relatively narrow tube-receiving channels.

3. The improvement defined in claim 2 wherein said pressure bars are each formed with bores extending generally parallel to the axis of rotation of said head and at each end of the respective crescent, at least one bore of each of said pressure bars being aligned with bores of the other pressure bars, the last-mentioned means including a hinge pin extending through the aligned bores and permitting swinging movement of said bars about said hinge pin and an axis parallel to the axis of rotation of said head.

4. The improvement defined in claim 3, further comprising at least one swivel clamp engageable with an end of one of said crescents remote from said pin.

5. The improvement defined in claim 3, further comprising a rod extending through the other bores of all of said pressure bars for joint swinging movement thereof, and clamp means engageable with at least one of said bars for retaining same in a predetermined position relative to said head.

6. The improvement defined in claim 3 wherein each of said disks is formed with a central noncircular opening, said pump further comprising a shaft of noncircular cross-section passing through said openings and constituting said keying means.

7. The improvement defined in claim 6 wherein said shaft and said openings are provided with complementary flats along chords over a segment and said rollers are arrayed mirror-symmetrically with respect to a plane perpendicular to said disks through the center thereof and the respective chord of the opening perpendicular thereto and with respect to a further plane through said center perpendicular to the first-mentioned plane.

8. The improvement defined in claim 7, further comprising a flexible strip extending around the rollers of each of said disks and interposable between said rollers and a tube disposed between said rollers and the respective pressure bar, and means for anchoring said strip against rotation with said head.

9. The improvement defined in claim 8 wherein said strips are composed of nylon.

10. In a peristaltic pump having a rotatable head with an annular array of equispaced rollers and a pressure member for retaining a flexible tube between itself and said rollers and extending over an arc of said head, the improvement which comprises a flexible strip extending around said rollers over said arc and interposable between said rollers and said tube, and means for anchoring said strip against rotation, said head being formed with a plurality of axially spaced channels each provided with an array of said rollers, said pressure member bearing upon a respective tube received in each of said channels, said pump being provided with such anchored flexible strips between each array of rollers and a respective tube.

11. The improvement defined in claim 10 wherein said strips are composed of nylon.

12. The improvement defined in claim 11 wherein said means for anchoring said strip comprises a body spaced from said head and a resilient plate having at least one finger deflectable upon insertion of said strip between said body and said finger and clamping said strip against said body.