Description of the Invention
This invention relates to peristaltic pumps and fluid conduits therefor, and more particularly to a pharmaceutically usable digitally incrementally driven rotary peristaltic pump arrangement and control method, and to a set of associated special different-sized tube set conduits interchangeably interengageable in operationally connected relation with the pump to effect appropriately responsive control of the total actuation of the pump for a selected volume of fluid to be pumped through a particular one of the set of plural different-sized tube sets that may be operationally connected to the pump.
Both sterile injectable syringes for syringe infusers, PCA systems or hypodermic/IV push use and nonsterile oral liquid syringes are filled in pharmacies. Sizes range from 1 ml to 60 ml. Oral liquids often are viscous or heavy suspensions.
Vials containing from 5 ml to 60 ml are filled for delivery of unit doses of oral liquids. The oral liquids are often viscous or heavy suspensions.
Most of the reconstitution of lyophylized and other dry powder drugs requires the addition of 50 ml or 100 ml to vials or, in the case of Lilly Fastpak, a plastic pouch. Accuracy is not always a major factor when the total contents of the vial are administered to a single patient. However, in many cases there will be a bulk medication vial where the contents are subdivided and administered in multiple doses. In this case, relatively close accuracy is required to obtain an acceptable degree of accuracy for a desired concentration in milligrams of drug per milliliter of solution. In all reconstitution work, speed is also very desirable. To the best of my knowledge, the fastest pump prior to this invention has been the ADS 100, which pumps at a speed of 9.6 ml/sec.
There are many fluid transfers required in preparation of special IV solutions or other injectable drugs. Often this involves the addition of electrolytes or vitamins to the standard preparations.
In Total Parenteral Nutrition (TPN) preparation, there are usually three or four components consisting of up to seventy percent (70%) dextrose, amino acids, saline and sometimes a fat emulsion, where higher caloric intake is required. In addition, there may be many other small-volume additions of electrolytes such as KC1 and many trace elements such as zinc, magnesium, etc. Many of these additions are done with syringes and sometimes a repeating syringe, which has a spring return plunger and a double check valve which allows fluid to be drawn into the syringe as well as expressed.
There are a number of applications where there is a need to collect the contents of a number of vials into a large sterile bag or bottle for redistsribution into a number of syringes. This is a typical step prior to sterile syringe filling.
There is also a need to fill drug containers which take the form of rubber balloons which have to be inflated. This requires a pressure of more than 12 psi, and is very difficult to do by hand using the present industry practice of filling with a syringe.
As can be seen from the foregoing discussion of various needs of pharmacy operation, there is a need for a high-speed and a very accurate pump. There is also a need for the pump to have speed adjustment for enabling pumping various different viscosity solutions, including very viscous solutions, or to accommodate high-outlet line-back pressure caused by small needles or filters in the line. In all cases, the volumetric delivery of peristaltic pumps will vary considerably with changes in line-back pressure. Peristaltic pumps are well-suited for high-speed fluid delivery, but they will not have predictable accuracy of delivery when back pressure changes.
Various prior peristaltic pump arrangements have been employed for pharmaceutical fluid filling.
One prior art pump known as the Wheaton pump is provided in two types, single speed and variable speed, and uses a two-roller rotary peristaltic system. The pump will accept several different-sized tube diameters. The volume is set by reference to data previously developed, which relates the volume delivered with the time of rotation. The pump uses an electric motor drive with a clutch-brake system. The user must modify the time setting to make volume adjustments. The Wheaton pump was originally designed for laboratory use in filling culture media.
Another pump known as the ADS 100 pump is a fixed-speed pump using the German Hein dual roller peristaltic pump head. It uses only one size tube with a 6 mm inside diameter and a 2 mm wall. The pump delivers 9.6 ml/sec. There is no accuracy-adjustment system. The tube sets are calibrated to provide reasonable accuracy at deliveries of 50 ml or higher with adjustments. The pump was designed to provide a means of adding diluent to Lilly Fastpak bag for reconstituting dry powder drugs.
In the Bard pump, which is used to fill 10 ml-50 ml syringes, one at a time, the Barnant pump system is employed, which uses a PVC pump tube requiring disassembly of the pump head with tools, in order to install new tube sets. It is fixed-speed, and relatively slow.
Another prior art pump known as the Acacia pump has been recently introduced, this being a private-label pump made by Manostat. It has a digital input and readout system with a microprocessor control. Tube size must be input manually by use of a designated program number for each tube size. The volume is set by reference to preestablished data relating rotation-time-to-volume-delivered.
Other prior art pumps include the BD pump and the Solopak pump (Barnant), both of which appear to be very similar to the Bard pump.
The presently available Acacia tube sets (U.S. Pat. No. 4,347,874) are used in conjunction with the Wheaton pump or the Physio Control (Lilly) pump. The patent describes prior art used for the transfer of diluent to dry powder held in vials of IV piggyback containers. Typically, 50 ml of diluent is added to a 100 ml vial. The prior art described in the patent disclosed the use of a secondary transfer set which is attached to the inlet end of a sterile silicone tube which has a vented needle on the outlet end. The patent is related to the higher speed achieved by having a larger pump tube, but keeping the inlet and outlet tubes at less than half the outer diameters of the rubber pump tube.
Peristaltic pumps are ideal for pumping sterile fluids, since they use inexpensive fluid conduits in the form of flexible tube sets which can be sterile disposables and can be installed without problems of contamination.
It is an object of this invention to provide a peristaltic pump which will accommodate different sized tube sets that can be easily installed, in which the pump will automatically sense which one of at least two different sized tube sets is installed, and which will automatically compute the total rotation of the peristaltic rollers for a selected input volume, for that tube size, according to estimated, calculated, empirically determined or otherwise determined data for pumped volume per amount of pump rotation for the respective tube set sizes.
A further important object of the invention is to provide a peristaltic pump arrangement which can be easily adapted to serve substantially all of the needs discussed above which are required in pharmacy operation.
Still a further object of the invention is to provide a pump which is compact and in which tube sets are easily operationally connectable thereto and removable therefrom.
Another object is to maximize the pump speed and to maximize fluid delivery rate, while maintaining acceptable accuracy of fluid delivery, to an extent greater than other previously available pumps.
Another object is to provide a pump capable of reduced speed to handle very viscous solutions, or situations where fluid flow is restricted by devices such as small needles or filters.
Still a further object is to provide a pump/multiple tube set arrangement in which the same pump head accepts and is effectively operational with a variety of interchangeably operationally connectable different tube sizes, without need to mechanically change the rotor and stator dimensions or characteristics, and with desired changes in tube sets of different sizes being quickly and easily made, without any need for, or use of, of tools or exchanged parts.
The accuracy of a rotary peristaltic pump is dependent on a large number of variables, including inside diameter accuracy, wall thickness accuracy, length of the pump tube or stretch over the rollers, elasticity of the rubber, speed of the rotor, line suction pressure at the inlet and the flow restriction and outlet back pressure.
All of the above variables, and probably other factors also, make it impossible to precisely accurately compute the fluid output of a rotary peristaltic pump in terms of the total movement of pump rotor relative to the pumping conduit or tube set. It is an object and feature of one optional combination aspect of the invention to enable achievement of high accuracy with ease, by entering the actual first cycle delivered volume into the controls of the pump and to have this data used in computing the needed accuracy adjustment in total rotation movement of the pump rotor and its rollers, so that subsequent pumping cycles, under the same operating conditions and for the same volume, will be adjusted by the same accuracy adjustment factor and will thus have a highly accurate adjustment- corrected adjusted total rotor movement for the given volume.
For many pharmacy operations, the tube set employed, as well as other operating conditions such as inlet pressure drop and outlet back pressure, will remain constant for succeeding fill cycles, with the only change being the desired delivered volume. It is accordingly a further object and feature of a modification of the one aspect of the invention immediately indicated above that after an accuracy adjustment factor is determined for the first volume setting, such accuracy adjustment factor may thereafter be selectively automatically carried over and applied for additional fill cycles, including those fill cycles for which the volume is changed.
A further object is to be able to fill two syringes at a time as one of the options. There is a need for high-productivity syringe filling, and handling two syringes at a time will nearly double the productivity.
Another object of the invention is to provide a rotary peristaltic pump arrangement and method in which sensing means detect which of plural different sized pumping conduits, formed by tube sets having different sized pumping tube sections, are connected, and in which the quantity of rotor movement for delivery of a desired volume is automatically computed for any one of a set of plural selected sizes of tube sets, based on stored data which has been estimated, calculated, empirically or otherwise determined..
Still other objects, features and attendant advantages will be apparent from a reading of the following description of an illustrative and preferred embodiment and practice of the invention, taken in conjunction with the accompanying drawings, wherein:
FIG. 1 is an isometric illustration of a peristaltic pump embodiment according to the invention, taken as viewed from the front and top sides of the pump.
FIG. 2 is a schematic plan view illustrating the pump of FIG. 1 with one size of tube set operationally installed therein.
FIG. 2AA is an isometric illustration of one of the two anchoring connectors of the smaller sized tube set of FIG. 2.
FIG. 3 is a schematic plan view illustrating the pump of FIG. 1 with a second larger size tube set, having a larger sized peristaltic pumping tube section, operationally installed therein.
FIG. 3A is an isometric illustration of one of the two anchoring connectors of the larger sized tube set of FIG. 3.
FIG. 3B is a side elevation view of the larger tube set shown in FIG. 2.
FIG. 4 is a section view taken along Line IV--IV of FIG. 3.
FIG. 5 is a section view taken along Line V--V of FIG. 2, and illustrating the accommodation of two identical tube sets having the smaller sized pumping tubes of FIG. 2.
FIG. 6 is a schematic mechanical and electrical block diagram illustrating a pump, peristaltic pumping tube and pump control arrangement according to the invention.
FIG. 7 is a schematic meachanical and electrical block diagram illustrating a modification according to the invention.
Referring now in detail to the Figures of the drawings, a peristaltic pump 11 has a pump head which includes a rotor 21, a fixed stator 41 and spaced anchoring connection elements 71, 81 for slidably removably anchored connection thereto of any of several selected different sized conduits which may and preferably take the form of specially constructed tube sets 51 and 151 having specially configured anchor connectors 61, 61 and 161, 161 respectively, which enable both ease of anchored connection or attachment to the pump 11 as well as enabling the pump control arrangement to sense which size of a plurality of sizes of such tube sets is operationally connected to the pump.
Rotor 21 has four equally spaced tube-engageable rollers 23 each freely rotatably mounted on a drive sprocket formed by upper and lower spiders 27 with a central cylindrical spacer block 28 therebetween. Rollers 23 are each mounted on a respective shaft 25 press fit into opposing spiders 27.
The rollers 23 preferably have peripherally bevelled or tapered tube-retaining end flanges 23a at their opposite upper and lower ends, with a cylindrical wall section 23b connecting therebetween and which serves in conjunction with the facing surface 41a of stator 41 to effect rolling peristaltic squeezing of the particular sized tube set or other suitable conduit 51 or 151 which is operationally connected to the pump 11. Spiders 27 and spacer cylinder block 29 are suitably fixedly secured to radially centered drive shaft 31 as by a securing screw 33 and compression washer 35 or other suitable securing means. The drive shaft 31 may be suitably interfitted in positive driving relation to the spiders 27 and spacer block 29, as by a cross-sectionally noncircular complementary mating interfit therebetween such as formed by a square section of shaft 31 and a complementary square bore in each of the spiders 27 and spacer block 29 to assure positive nonslip driving of the rotor 21. The securing screw 33 and washer 35 may be suitably disposed in a recess 27b formed in the upper face of upper spider 27 to assure noninterference with the closing of a pivotally mounted cover 91, to be later described.
Pump 11 includes a housing 13 containing a stepping motor M actuated by a control arrangement to be later described, and which control arrangement is also preferably disposed within pump housing 13. Housing 13 has a recessed pump head floor surface 13s bounded by upstanding side walls 13a, 13b, an end wall 13c and end posts 13d, 13e and 13f, 13g forming a portion of anchoring connection elements 71 and 81 respectively.
The upper surfaces of side walls 13a and 13b and end posts 13d, 13e and 13e, 13f are preferably recessed below the surface of end wall 13c to enable closure of the cover 91 with its upper outer surface flush with the adjacent upper surface 13cs of end wall 13c. Likewise, the upper surface of stator 41 and the upper one of spiders 27 are preferably recessed below the cover support surfaces formed by the upper surfaces of walls 13a, 13b and 13c and end posts 13d, 13e and 13f, 13g.
Cover 91 is pivotally mounted on and forms a cover for the housing 13, being mounted as by a pivot shaft 93, shaft receiving bosses 95 and spaced bearings 97 in which shaft 93 may rotate to enable opening and closing of cover 91. Cover plate 99 of cover 91 preferably is formed of transparent or translucent material to enable external viewing of the pumphead therebeneath when the cover is closed. A finger-accommodating recess 13br may be formed in side wall 13b to enable ease of opening of the cover 91, as the cover plate 99 preferably extends over and rests on side wall 13b as well as side wall 13a in the closed position. The closure of the cover 91 aids in assuring effective switch actuation sensing seating of the tube sets 151 in anchoring connection elements 71 and 81, as will be later described.
Stator 41 has a curved peristaltic pumping action surface 41a having the same radial center of curvature as rotor 21, and which surface 41a faces rollers 23 at fixed spaced relation thereto along a constant radius over an angle p sufficient to assure effective peristaltic progressive roller-engaging squeezing action by the four 90 degree arcuately spaced parallel axis rollers 23. The fixed radius peristaltic action surface 41a of stator 41 is thus spaced a constant distance from the cylindrical surface 23b of each of rollers 23 as the rollers 23 progress past stator surface 41c in the peristaltic pumping action zone defined by the angle p as shown in FIGS. 2 and 3. The surface 23b of each of rollers 23 together with the stator surface 41c serve to progressively squeeze the elastically compressible flexible peristaltic pumping tube section 55 or 155 which may suitably be formed of silicone rubber or other desired material, of tube set pumping conduits 51 or 151, to thereby progressively move the squeeze zone along the length of the constant radius surface 41c of stator 41, so as to force the liquid content in peristaltic pumping tube section 55 or 155 along this tube section in the direction of rotary motion of the rotor 21, which in the illustsrative embodiment is in a counterclockwise direction as viewed in the respective Figures.
In the illustrated and preferred embodiment the pump head employs four rollers 23. To pump effectively there must always be at least one roller 23 squeezing the tube section 55 or 155 at any rotary position of the rotor 21. Thus, for the four roller sprocket rotor of this embodiment, the fixed curved stator surface 41c must extend over an angle of arc p of at least 90 degrees. In practice it has been found that an angle of arc p in the range of approximately 110 degrees to 130 degrees is preferable and affords best results for this embodiment.
For the pump 11 to be able to utilize and operate with tube set conduits which have several different delivery rates for the same rotation speed pump rotor 21, such may be effected with interchangeably matched sets of tube set conduits 51 and 151, the respective pumping tube sections 55 and 155 of which tube set conduits 51 and 151 have selected respectively different diameters. In one illustrative and preferred embodiment of this invention, different sized tube sets may be employed which respectively utilize a large pumping tube 153 of 6 mm ID and 2 mm wall thickness for the high flow rate, and tube set 51 with a smaller 3 mm ID and 2 mm wall thickness of its pumping tube section 53 for a lower flow rate. Alternatively, a tube set having 1.5 mm ID and 2 mm wall thickness may be employed as one of a set of two different sizes of tube sets 51, 151, to thereby provide for micro flow rate filling. As can be seen, the wall thickness is the same for all of the pumping tubes 55 and 155, which permits interchangeable operation with the same spacing between the roller and fixed surface. This allows the changing to different tube sets 51 and 151 without mechanical changes to the rotary pump section.
The roller surfaces 23b and curved stator surface 41c are parallel to one another and are parallel to the axis of rotor 21. As shown in FIG. 5, the roller surfaces 23b have an axially extending length sufficient to accommodate optionally either one or two of the smaller sized tube set peristaltic pumping tube sections 55 of a given size, which in one illustrative embodiment is a peristaltic pumping tube section 55 of 3 mm ID and 2 mm wall thickness.
It will be appreciated that the radial clearance space between roller surface 23b and the facing fixed radius curved stator surface 41a must be such that the pumping tube squeezed therebetween is closed off at the squeeze zone. Accordingly, this roller/stator surface radial clearance spacing must be less than twice the wall thickness of the pumping tubes 55 and 155 or 153.
The length of the roller surfaces 23b in the illustrative embodiment will accommodate one of larger size tube set 51 having in one illustsrative embodiment an ID of 6 mm and a wall thickness of 2 mm. However, by extending the axial length of the parallel roller and stator squeeze surfaces 23b and 41a, more tube sets and/or still larger tube sets may readily be accommodated. It is to be noted and is an important feature of one aspect of the invention that the wall thickness is the same for each of the various pumping tube sections 55 and 155 having respectively different IDs.
By employing an equal wall thickness for the pumping tube section 55 and 155 of each of the various sized tube sets with different IDs, matched sets of various tube set sizes having respectively different IDs are provided, all of which various sized tube sets 51, 151, with matched equal wall thickness pumping tube sections 55, 155, may be used interchangeably on the pump 11 without necessity for mechanical change to the pump head components, including rotor 21 and stator 41.
By way of example of operation of an illustrative embodiment of the invention, the delivery rate by the pump through the tube sets 51, 151, etc. in one illustrative embodiment of the pump 11 and tube sets 51, 151 are 10.5 ml/sec for the high-flow 6 mm ID tube, and 2.6 ml/sec for the low-flow tube sets with 3 mm ID pumping tube sections. The corresponding delivery rate for one illustrative micro flow tube set with 1.5 mm ID is 0.65 ml/sec. There is a need for the different size tubes in pharmacy practice, since there are needs for both high-speed filling of volumes of 10 ml or greater up to a liter or more, whree fill=cycle-to-fill-cycle repeatability accuracy of .+-.0.3 ml is acceptable and for greater accuracy filling of lesser volume quantities. This is the accuracy which has been achieved with an embodiment of pump 11 pumping through a 6 mm ID tube section 155. The degree of inaccuracy is due to the overall electromechanical system tolerances which can affect the total movement of the squeezing roller, as well as delivery changes due to the positions of the rollers on the fixed arc at the beginning and end of the cycle.
Greater accuracy is needed for smaller volume filling. An illustrative tube set 51 with a 3 mm ID pumping tube section 55 tube set embodiment has provided a fill-cycle respectability accuracy of .+-.0.08 ml, while a micro-filling tube set having a 1.5 mm ID pumping tube section 55 has provided a fill-cycle repeatability accuracy of .+-.0.02 ml. For 1 ml fills the small micro tube having the 1.5 mm ID will then fill with an acceptable accuracy of .+-.2%, or .+-.4% if filling 1/2 ml.
For users to be able to easily use the different sized tube sets 51 and 151 in the pump 21, it is very desirable for each of the tube sets to be easily placed in and connected to and removed from the pump 11.
It is also highly desirable that the pump 11 have means for automatically sensing which of a plurality of different sizes of tube sets is operationally connected to the pump, and for making automatic adjustment, if required, in the computation of the amount of rotor rotation required per unit volume to be pumped through a given size tube set connected thereto. Such automatic adjustment is effected by actuation of a suitable switch as a function of fully seated anchored connection of a given tube set to pump 11, and in the illustrated embodiment such is effected by a switch sensor 229a which extends in transversely movable relation through an opening in the lower outer end of slot sidewall 84, the sloped cam surface on its slot-facing protruding end to enable outwardly transverse switch-actuating displacement thereof by downward vertical sliding contact therewith of a flange portion of an appropriate given tube set as a function of slidably anchored connection of such tube set anchor connection into slot 84.
Such adjustments may be made based on calculations of fluid flow, empirical evidence as by prior calibrated testing and extrapolation, educated estimates, etc. for pumping a given unit volume or total volume of fluid with a selected size tube set (e.g., 51 or 151) having a particular ID pumping tube section (e.g. 55 or 155).
Each of two different sized tube sets 51 and 151, having respectively different ID-sized pumping tube sections 55 and 155 having the same wall thickness, are formed with inlet tubes 53 and 153 and outlet tubes 57 and 157 connected to the opposite ends of their respective pumping tube section 55 and 155, through the medium of anchor connectors 61 and 161 formed respectively thereon. The inlet and outlet tubes 53, 153 and 57, 157 may have any desired end connection fitting thereon as may be desired for a given utilization, as for example, vented or nonvented connectors, male or female Luer Lock connectors, weighted ends, filling bag inlet connectors, spike connectors, etc. In the illustrative embodiments, each of the inlet tubes 53 and 153 has a conventional nonvented IV bag spike connector 53a and 153a suitably secured thereon, while the outlet tubes have a conventional male Luer Lock connector 57a and 157a thereon, and a conventional manually operable off/on tube clamp 159 is mounted on each of the outlet tubes 57 and 157. The outlet tubes may suitably be formed of flexible plastic, such as polyvinylchloride (PVC) or other desired and suitable material, and the size of the inlet tubes 53 and 153 will normally be larger than the outlet tubes 57 and 157, and both inlet and outlet tubes may acceptably be somewhat smaller than the peristaltic pumping tube section, the ID size of which pumping tube section is the primary factor in the rate of peristaltic pumped fluid flow through a given tube set, assuming that the inlet tube is of sufficient size to accommodate the flow of fluid without collapsing, and the outlet tube and any unit connected thereto is not unduly restrictive so as to unduly restrict the flow which the pumping tube section is capable of pumping. In the illustrative and preferred embodiments it will be noted that the inlet tubes 53 and 153 for each of tube sets 51 and 151 have the same diameter size, as do likewise the respective outlet tubes 57 and 157, although different sizes for these corresponding tube sections may be employed if so desired. In general, a relatively wide latitude of inlet and outlet tube sizes and end connections may be accommodated, as may be deemed desirable in a given application.
Anchoring connection elements 71 and 81 have transverse slots 72 and 82 formed therein for interchangeably receiving anchor connector flanges 61 and 161 on each of the two different sizes of tube sets 51 and 151. Transverse slots 72 and 82 are formed respectively by opposed parallel side walls 74, 75 and 84, 85, and opposed parallel centrally split end walls 76, 77, 78, 79 and 86, 87, 88, 89, the split end walls having a longitudinal slot 73 and 83 respectively formed therein to slidably receive and accommodate the longitudinally opposite end sections of the anchor connector flanges 61 and 161. The primary guiding and anchored connecting and locating action both longitudinally and transversely or laterally on the tube set anchor connectors 61 and 161 is effected by the opposing side walls 74, 75 and 84, 85 and end walls 76, 77, 78 79 and 86, 87, 88, 89. End walls 73, 74 and 83, 84 are formed by an end plate 90 secured to the end face of the body of housing 13 as by securing strips 90a and 90b secured in place as by securing screws, brads, etc. (not shown) extending through plate 90 and into the adjacent face of the body of housing 13.
The anchor connectors 61 on the smaller sized tube set 51 are mutually interchangeably identical, and take the form of longitudinally spaced flanges or flange sections 63 and 67, while the anchor connectors 161 on tube set 151, which are also mutually interchangeably identical, take the form of longitudinally spaced flanges or flange sections 163 and 165, 167. Flanges 63, 63 on tube set 51 and flanges 163, 163 on tube set 151 are disposed adjacent the connector ends 62, 162 over which the respective pumping tube sections 55 and 155 are stretch-fitted and secured, the larger ID pumping tube section 155 having a suitable securing ring 166 thereabout, such as a tie ring or an o-ring, while the smaller ID tube section 55 may be suitably self-retained on the respective connector ends 62 through the elastic stretch-fit of its opposite ends over the respective connector ends 62.
The anchor connectors 61, 161 on the smaller sized tube sets 51 are devoid of means for operatively actuating a pump operation control switch 229, while the anchor connectors 161, 161 on the larger sized tube sets have operative switch actuating means thereon in the form of transverse oblong rectangular flanges 165, the transversely oppositely facing outer parallel surfaces of the longer of the pairs of side walls 165a thereof forming sliding switch sensor-contacting and movement-effecting surfaces which laterally displace the switch sensor 229a to thereby effectively operate the switch 229 from normally open position to a closed position, for control circuit operational purposes as will be described more particularly in the description of FIGS. 6 and 7.
If desired, the combined thickness of end plate 90 securing plate 90a may be made greater than the distance between flanges 63 and 67 of tube sets 51, and flanges 163 and 165, 167 of tube sets 161, to assure against inadvertent improper connection of the anchor connectors 61 and/or 161 with their flanges 63 and/or 163 within the anchor connection slots 74 and 84 and with their flanges 67 and 165, 167 lying outside the slots 74 and 84 and adjacent the outer faces of end plate 90 and securing plates 90a, 90a. Likewise, the thickness of the anchor connection elements forming opposite end walls 76, 77, 86, 87 is preferably greater than the distance between flanges 63 and 67 and flanges 163 and 165, 167.
To effect these ends, while also providing effective longitudinal and transverse or lateral anchoring connection and removal of the anchor connectors 61, 61 and 161, 161 with pump anchoring connections 72 and 82 in an easy and facile manner, both of the anchor connectors 61, 61 and 161, 161 have in common a square rectangular transverse flange 163 adjoining the connector end thereof connected to the respective pumping tubes 55, 155. The square flanges 63, 63 and 163, 163 extend perpendicular to the length of the respective connectors 61, 61 and 161, 161, of which they form a part, and have a length along each square wall side sufficiently smaller than the transverse width between equally spaced apart slot side walls 72, 74 and 82, 84, so as to provide a complementarily snug but freely vertically slidable fit within both of the slots 72 and 82. Square flanges 63, 63 and 163, 163 serve as primary transverse and longitudinal anchoring and locating means for the connectors 61, 61 and 161, 161 and concomitantly for anchored connection of their respective interconnected pumping tube sections 55 and 155 on the pump 11.
At the longitudinally opposite outer ends of each of anchor connectors 61, 61 and 161, 161, each anchor connector has a further transverse flange 67, acting to effect sliding physicalcontact with and switch-actuating displacement 67 and 165, 167, 165, 167, respectively; the flanges 165, 167 and 165, 167 of switch sensor 229a as a function of sliding anchoring seated insertion of either of the anchor connectors 161, 161 within slot 82. On the other hand, the flanges 67, 67 are configured and located such that they serve as longitudinal slot retention and displacement anchoring means similarly to anchor flanges, while having no part thereof which intercepts and actuatingly moves switch sensor 229a along any portion of the insertion and seating path of either of the anchor connectors 61, 61 within slot 82. This may be accomplished in any one or more of several ways, such as by forming the flat cylindrical flange 67 of a sufficiently small diameter and physically locating the switch sensor 229a in an opening in the slot wall 84 forward of the insertion path and seated location of square flanges 63, 63; and vertically below the outermost circular rim portion of the small-diameter flat cylindrical flanges 67, 67 and extending a sufficiently small extent into the slot 82 such that it is out of any effective actuating contact by either flanges 63, 63 or flanges 67, 67 when the square flanges 63, 63 are fully seated on the floor 13s, which forms the bottom of slot 82, and/or by locating the switch sensor 229a longitudinally along slot wall 84 such that the anchoring insertion and seating physical displacement path of flanges 63, 63 and 67, 67 within slot 82 will not actuatably intercept the switch sensor 229a. As an alternative, the switch sensor 229a may be simply located longitudinally in slot wall 84 such that it is spaced longitudinally between and away from each of the longitudinally facing flat end surfaces of both flanges 63 and 67, while forming the oblong rectangular flanges 165, 165, with their respective opposite long switch-actuatable side walls 165a with a longitudinal wall thickness or displacement such that either of these side walls will actuatably intercept and displace switch sensor 229a as a function of anchoring seated insertion of anchor connectors 161, 161 within slot 82. Or the entire flange zone of anchor connectors 161 may be formed as a single locating, anchoring and switch-sensor contacting and actuating unitary flange block surface complementarily snugly fitting along all of or a major part of the inner end zone of, the length of slot wall surfaces 72, 74, 82, 84, so as to enable a wide latitude of switch sensor location while enabling use of a lesser or staggered length for the transversely outer guide surface or surfaces of the flanged anchor connectors 61, 61 so as to avoid switch sensor 229a actuation thereby. It will be apparent that various other selective switch-actuating/nonactuating arrangements may be employed in connection with various forms and constructions of anchor connectors 161, 61 and 161, 161, including employment and selective location of other switch and switch-sensor means such as magnetically actuated or optically actuated sensors.
The shorter of the opposite parallel side walls 165b of oblong rectangular flanges 165, 165 have substantially the same length as the length of each of the side walls of square flanges 163, 163 and 63, 63, and thus serve to additionally aid in transversely positioning and stabilizing the anchor connectors 161, 161 in slots 72 and 82.
The height of slots 72 and 82 preferably substantially corresponds to the length of the two longer switch-actuating parallel transverse side walls 165a, 165a of each of oblong rectangular flanges 165, 165, which length is also preferably generally twice that of the length of the smaller parallel side walls of each of flanges 165, 165 as well as the four side walls of square rectangular flanges 63, 63 on tube set 51. This assures that full anchoring seating of either of anchor connectors 161, 161 within slot 82 will effect switch-actuating lateral displacement of switch sensor 229a, while also enabling stacked disposition of two anchor connectors 61, 61 within each of slots 72 and 82 so as to enable anchored connection of each of the tube sets 51 on the pump 11 for simultaneous pumping action through both tube sets.
As an aid to more secure anchoring connection and to more precise positioning of the anchor connectors 61, 61 or 161, 161 within the pump anchor connection slots 72 and 82, the length of elastic peristaltic pumping tube sections 55 and 155 may be made of a length to require slight stretching to enable sliding anchored connecting engagement of each of the respective flanged anchor connectors 61, 61 and 161, 161 with its respective anchor-connection element slot 72, 83, thereby positioning the flanged anchor connectors 61, 61 and 161, 161 in a squared-up relationship flat against slot end walls 76, 77 and 86, 87.
As will be noted, the pump rotor 27 and stator surface 41a and anchor connection elements slots 72, 82 are all open at their upper ends, thereby enabling ease of installation and removal of a selected one of tube sets 51 and 151. The pumping tube sections 53 and 153 of either of the tube sets 51 or 151 may thus be simply progressively walked between rotor rollers 23 and stator surface 41a while rotating rotor 21 by hand, and thereupon the respective flanged anchor connectors 61, 61 or 161, 161 are gently pulled sufficiently to enable them to be slidably inserted and effectively anchored in substantially transversely centered relation within anchoring connection element slots 72 and 82. As an aid to preventing inadvertent catching of the pumping tube sections beneath the lower spider 27 of rotor 21, a slightly raised surface guide shelf 13sg may be formed on the recessed pump head floor surface 13s of housing 13 as shown particularly in FIGS. 4 and 5.
As previously noted, closure of cover 91 aids in assuring full seating of the switch-actuating flanged anchor connectors 161, 161 in their respective vertically open slots 72, 82 to assure switch actuation by a respective fully seated flanged anchor connector 161 within slot 82 having switch-actuating sensor 229a extending therein through side wall 84. By forming the cover plate 99 of generally transparent material, the pumping action by rotor 21 on the installed tube set 51 or 151 may be readily observed and monitored. Likewise, the height of each of slots 72 and 82 is sufficient to accommodate two of the flanged anchor connectors 61, 61 in vertically stacked seated relation therein, and this aspect together with the length of roller surfaces 23b enables the concurrent operative attachment of two of the smaller sized tube sets 51 about the rotor 21 and within anchoring connection element slots 72 and 82 for simultaneous dual pumping of fluid therethrough.
Referring now to FIG. 6, a suitable clock generator 211, which may be formed by a fixed-rate or adjustable-rate oscillator (although a stable fixed frequency oscillator such as a quartz controlled oscillator is preferred) feeds a higher frequency (e.g., 4 Mhz) signal than will be utilized for pump operation, through an adjustable divider 213 which provides a suitable lower frequency signal which is within a frequency range acceptable by stepping motor M. The output frequency of divider 213 may be suitably controllably varied by a speed control 13a which may function to vary the speed of motor M by varying the divisor y inputted to divider 213. The desired suitably lower frequency signal output from divider 213 is fed to a pulse generator 215 which forms pulses at the same frequency as the input signal thereto from divider 213, and having pulse characteristics suitable for driving a rotary stepping motor M which in turn rotates shaft 31 and rotor 21 of peristaltic pump 11, relative to stator 41.
A suitable switch 229, such as a microswitch, is suitably disposed in housing 13 with a switch-actuating sensor 229a therefor disposed adjacent one of the anchoring connection element slots 72, 82 for operative engagement by a particular selected configuration of flange 165 in the illustrated embodiment, to thereby enable automatic tube set responsive control of the quantity of pulse counts fed to an accumulated count register 55 per pulse-driven increment of rotational movement of pump rotor 21.
The simple mechanically actuatable on-off switch 229 enables accommodation of two different inner cross-sectional sized tube set conduits 51 and 151, and to this end the switch 229 controls an OR gate 251 which effectively switches the output signal of divider 213 either to feed directly to an accumulator register 255, or feeds this signal to the register 255 through a multiplier or divider 253 which applies an appropriate set multiplication or divide factor b suitable to correct for the calculated or estimated (as by empirical testing) different fluid flow rate through one of the two differently sized conduits 51 or 151 relative to the fluid flow rate through the other sized conduit 151 or 51. Thus, for instance, assuming the larger diameter conduit to have the switch-actuating flanged anchor connectors 161, 161, as in the illustrative embodiment, and the normal condition of OR gate to be direct to accumulator register 253, the adjuster 253 would be a multiplier with a multiplying factor b equal to the calculated, or preferably empirically tested and determined, ratio of pumped flow rate through the larger conduit 151 by peristaltic pump 20 relative to the flow rate through the other smaller conduit whose flanged anchor connectors 61, 61 are configured so as not to actuate switch 229 when such smaller conduit is connected and anchored in place on the pump 11. Vice versa, if the normal condition of OR gate 251 is through adjuster 253 and the larger sized conduit 151 has the actuating flanged anchor connectors 161, 161 thereon, the adjuster 253 in such a case could suitably be a divider, with an appropriate division factor b, or if a multiplier were employed, the factor b would be suitably less than unity (i.e., 1/b) to provide the desired differential in counts fed to the accumulator register 55 during respective pumping through the two differently sized conduits 51 or 151. The reverse of these arrangements could be applied if the smaller of the tube sets 61 had the switch-actuating flanged anchor connectors 161, 161 formed thereon.
Any of several different switching arrangements may be employed, as may be desired, to effect the desired differential count registry in accumulator register 255. Also, while a simple flange-actuated switch arrangement 229, 229a is illustrated and preferred, various other types of sensors and switches could be employed, such as magnetic or optical switches with an appropriate actuator on the respective actuating conduit. Further more complex switching arrangements, as with additional series cascaded and/or parallel switches and/or signal control gates, might be employed to sense and accommodate more than two different sized conduits if so desired with appropriate selectively usable multiplier/divider adjusters for the various sized conduits.
The output of count accumulator register 255 is continuously inputted to a comparator 257 whose other input is from a desired end count register 261. When the count accumulator register 255 has accumulated a count equal to that in the desired end count register 261, the comparator 257 actuates and opens previously closed motor start/stop control switch 259 to thereby stop the feeding of pulses to the motor M, thus effectively stopping the motor and cutting off further pumping by the pump 11.
The desired end count register 261 is set to a desired value by inputting a desired volume and/or by subsequently inputting an actual measured volume V.sub.M resulting from operation of the pump 11 based on the initial setting of a desired volume V.sub.D. As is subsequently described, the measured volume V.sub.M may be utilized in conjunction with the desired volume V.sub.D to adjust the desired end count register 261 to reflect any noted difference in actual flow rate through the given conduit 51 or 151 relative to the expected estimated or calculated flow rate.
Desired volume V.sub.D may be suitably inputted in digital form at desired volume input 271 as by a touch pad or keyboard which accommodates volume quantity inputs, e.g., liter, ml, etc, and this input 271 is fed to a multiplier 273 which converts the value V.sub.D to a suitable corresponding count by (V.sub.D)(n) by multiplication by a constant n which correlates with the pulse quantity/volume estimated or calculated to be pumped by the stepper motor-driven pump 11 for a pumping conduit of the base size which causes direct feeding of count accumulator register 255, as distinguished from the indirect feeding thereof through multiply/divide adjuster 253.
The resulant product output (V.sub.D)(n) is fed to a desired volume estimated count register 275 which has been suitably reset to zero prior to entry of the desired volume count (V.sub.D)(n) Initially, the output (V.sub.D)(n) of register 275 is passed through OR gate 277 to the desired end count register 261, the output of which register 261 in turn is inputted as one comparison input to comparator 257, against which comparison input the comparator compares as its other comparison input the running count accumulation output from count accumulator register 255.
Thus, when the set quantity in register 261 is equalled by the accumulated count in register 255 the comparator 257 will actuate the motor start/stop switch 259 to off or open condition, where it will remain until it is again manually or otherwise suitably automatically or otherwise reactuated to on or closed condition.
While one particular illustsrative and preferred mode of practice of an arrangement and method is illustrated and described according to this aspect of the invention which effects automatic adjustment of the number of pump pulses applied to pump a given desired quantity of fluid to compensate for differences in pumping conduit internal size is illustrated and described, it will be apparent that this aspect of the invention may be effected with various other arrangements and modes of practice. For instance, in lieu of adjusting the actual resulting running count corresponding to the pulse count to the motor M and which is employed as one comparison input, the representation of the desired volume input value V.sub.D or the product (V.sub.D)(n) may be alternatively appropriately selectively multiply/divide-adjusted or not and fed through a switch-controlled OR gate which may be controlled by switch 229. Suitable flow locations for insertion of such OR gate controlled adjust/nonadjust count control could be between multiplier 273 and register 275 or between input 271 and multiplier 273. Or the multiplier 273 or an additional multiplier could be controlled as a function of actuation of switch 229 to provide a different total multiple of the selected desired value V.sub.D, as a function of whether switch 229 is actuated or not. The particular arrangement or mode of practice is widely variable and various modes of practice will be readily apparent to those skilled in the art when following the broad teachings herein of my invention, and as the particularities of the selected mode of practice do not form a part of the invention, such will not be further illustrated or described in detail.
There are many variables affecting the accuracy of a specific tube set and application. The pump may calculate the theoretical or estimated required number of rotary steps for a known tube diameter, pump speed, inlet and outlet pressure and other variables if known. However, as a practical matter for a pump such as this with a wide variety of applications, it is not possible to know all of the variables. In addition, there will be some tolerance in the tube dimensions or physical characteristics which will affect accuracy.
To provide the user with a simple and easy recalibration adjustment, this invention utilizes a means of inputting the actual delivered volume from a measured initial test volume delivered by the pump. The computer control will then calculate the ratio of the desired volume relative to the actual delivered volume and use this ratio to modify the number of pulsed rotary steps of the stepping motor to provide the desired correct volume. the computer may then selectively retain the adjustment or correction ratio in memory, if desired, so that this correction can be made for subsequent input desired volume pumping cycles when the same tube set and inlet/outlet conditions exist.
While the calculated or estimated value n of pulses/unit volume as employed may provide an acceptable degree of accuracy in some instances, as noted above, there may nevertheless be situations where greater accuracy is required in the actual volume of fluid delivered. To this end, as generally and briefly discussed above according to another aspect of the invention, provision is made for adjustment of the desired volume estimated count value (V.sub.D)(n) by a factor which effectively substantially compensates for the difference between the desired pumped volume and the actual measured pumped volume V.sub.M resulting from use of the calculated or estimated pulses/quantity pumped. According to a preferred mode of practice of this aspect of the invention, after conclusion of operation of the pump 11 with a given tube set fluid conduit 51 or 151 and fluid being pumped, the volume V.sub.M of fluid pumped from the conduit 51 or 151 is measured, either visually or otherwise as desired. It has been found that, for most normal conditions and requirements, personal visual measurement is adequate to provide an acceptable basis for adjustment of the pumped volume V.sub.M to a value well within acceptable tolerance limits relative to the desired volume V.sub.D.
According to this aspect of the invention, the measured volume V.sub.M, resulting from operation of the pump when a desired volume V.sub.D has been inputted, is inputted as through manual actuation of measured volume input unit 281, which may be a keyboard, touchpad or other suitable digital input device, the measured value V.sub.M being inputted being in the same selected unit of measure quantity as employed for inputting the desired input V.sub.D. This value is multiplied in multiplier 283 by the factor n to provide a measured volume count (V.sub.M)(n) which is inputted to cleared measured volume count register 285, the output (V.sub.M)(n) of which is i putted as the divisor to divider 287. Also inputted to divider 287 as the dividend therefor is the count value (V.sub.D)(n) from the volume estimated count register 275. The quotient V.sub.D /V.sub.M output from divider 287 reflects in usable nearest digital count value the ratio of the desired volume V.sub.D relative to the actual measured volume V.sub.M produced by employing the estimated or calculated multiple n to provide the pulse quantity (V.sub.D)(n) for operation of the pump 11 in an effort to pump the desired volume V.sub.D.
Output V.sub.D /V.sub.M from divider 287 is fed through selectively opened normally closed gate 288 into cleared register 289, after which gate 288 is closed until a new value V.sub.D /V.sub.M is desired to be inputted to register 289, at which latter time register 289 may be cleared by its reset input, and gate control 288a may be actuated to open gate 288 and permit passage of the new value of V.sub.D /V.sub.M into V.sub.D /V.sub.M register 89. The output V from register 289 is continuously available and inputted as one multiplier input into multiplier 291, the other input to multiplier 291 being the desired volume estimated count (V.sub.D)(n) from register 275. The product (V.sub.D.sup.2)(n)/(V.sub.M) is a count value (which may be suitably rounded off to the nearest whole digital value) which reflects the original estimated count V.sub.D (n) adjusted by the ratio or percentage adjustment factor V.sub.D /V.sub.M to thereby make a correction for the measured variation in pumped quantity resulting from use of this count value (V.sub.D)(n) as the pulse generating input for pump 11.
Register 261 is suitably reset/cleared, and the OR gate 277 is thereupon actuated by a suitable gate control 279 to switch the input to the cleared desired end count register 261 so that the output (V.sub.D.sup.2)(n)/(V.sub.M) is inputted through OR gate 277 to the desired end count register 261. Thereupon, the pump 11 is restarted by actuation of start/stop switch 259, and when the count accumulator register 255 registers the same number of counts as the count value (V.sub.D.sup.2)(n)/V.sub.M outputted from the desired end count register 261, the comparator 257 effects an output signal which actuates the on/off switch to its normal off condition, thereby stopping the pulse drive actuation of motor M and pump 11 driven thereby. The pumped quantity of the given fluid through the given tube set conduit 51 or 151 will thus be an amount which is adjusted for the measured difference between the desired volume V.sub.D and the measured volume V.sub.M, the adjustment being an increase or decrease reflected by the adjustment factor ratio of the desired volume V.sub.D relative to the measured volume V.sub.M.
The V.sub.D /V.sub.M register 289 may retain its registered value until such register is reset and gate 288 is subsequently opened to enable registry of a new value V.sub.D /V.sub.M therein, as may result from pumping action with different conditions, such as using different pumping conduit 51 or 151 , and/or pumping a different fluid. Thus, by retaining the value V.sub.D /V.sub.M in memory register 289, additional further desired volume quantities V.sub.D, which may be the same as previously inputted at desired volume input 271, may again be outputted as desired by pump 11 by merely start reactuating start/stop switch 259, as the desired end count register 261 will retain the adjusted desired end count for the previous desired volume input V.sub.D until reset. Alternatively, the previously determined ratio value V.sub.D /V.sub.M may be retained in register 89 and reused as a further adjustment factor input to multiplier 91, for a desired new input value of V.sub.D inputted through input 271 and multiplier 273 to cleared desired volume estimated count register 275; and by operating OR gate 277 to pass the resulting output (V.sub.D.sup.2)(n)/(V.sub.M) to desired end count register 261, the same previously resulting correction or adjustment factor V.sub.D /V.sub.M applicable for operation of the pump 11 to pump an identically proportionately adjusted more accurate quantity of fluid, will be reflected in the pump operation, without necessity for again measuring the quantity pumped and inputting such through input 281, with essentially the same degree of corrected accuracy, assuming the same conditions are maintained for the pump, including same pump speed, same conduit, and same fluid, etc., the only operating difference being the desired volume quantity V.sub.D. When any condition other than desired volume to be pumped is changed, it is desirable that the V.sub.D /V.sub.M register be cleared, and the previously described test pumping, measuring and, if necessary, adjusting of fluid quantity pumped, by forming and registry in register 289 of a new adjustment factor V.sub.D /V.sub.M by appropriately opening and then closing of gate 288, as by gate control 288a.
If desired where the accuracy enhancing feature involving inputting of the measured actual pumped volume is not required, the portions of the circuit of FIG. 6 for carrying out this feature may be omitted. An electromechanical block diagram illustrating this modification is shown in FIG. 7, in which the tube set 161 is shown for illustrative purposes. The various operating elements of the system as illustrated are similarly numbered and operate essentially the same as the corresponding operating elements of the embodiment and mode of practice of FIG. 6, as previously described above and such circuit will not be further described.
While the foregoing system and method has been illustrated and described generally in hardware form and terms, it will be appreciated that such may, and may in a given instance preferably, be effected in large measure by suitable corresponding software and/or firmware programming and operation of a computer or computers by such programming in conjunction with such hardware of the system as may be deemed desirable.
While the invention has been illustrated and described with respect to several illustrative embodiments and modes of practice, it will be apparent to those skilled in the art that various modifications and improvements may be made without departing from the scope and spirit of the invention. For example, other forms of pumps may be used in lieu of stepping motor-driven pumps, such as peristaltic pumps driven by a DC motor in conjunction with a digital output signal which is a function of the fluids pumping movement of the pump, which digital signal may then serve as the input to a digital count accumulator register such a count accumulator register 255 for comparison by comparator 257 with a digital value, either estimated or adjustment corrected, corresponding to the amount of pump movement required for pumping a desired quantity of fluid. Accordingly, the invention is not to be limited by the illustrative embodiments and modes of practice, but only by the scope of the appended claims.