US 2804023 A
Description (OCR text may contain errors)
' g- 1957 J. c. LEE 2,804,023
9 :37 INVENTOR.
g- 1957 J. c. LEE 2,804,023
Filed Nov. 29, 1954 2 Sheets-Sheet 2 IN V EN TOR.
John C. Lee, Park Forest, 11]., assignor,
ments, to Mr. Robot, Inc., of Illinois by mesne assign- Chicago, Ill., a corporation This invention relates to improvements in pumps, and particularly to pumps of the general type often termed traveling sling pumps or surgical pumps. In this general type of device, it has heretofore been more or less common practice to provide a resilient rubber tube with manipulating devices such as rollers, fingers or the like arranged to flatten and substantially close the tube progressively along a portion thereof, and thus to cause movement of fluids through the tube.
It is a primary object of the present invention to provide an improved pump of this general character, wherein the operating parts are so designed and so related to eachother as to avoid objectionable pulsing or surging, and to effect a relatively smooth and constant flow of fluid at the outlet of the pumping tube.
More specifically, it is an object of the present invention to provide a pump'of a design and construction particularly suited to use in connection with dispensing or vending apparatus arranged to pump milk directly from a bulk container into individual cups, with the pump functioning as the sole measuring apparatus of the unit. In such applications, of course, it is obvious that the pump should be of a design of substantially constant displacement in order that accurate measurement of the fluid dispensed shall be attained. It is equally important that the unit be so designed as to permit quick, easy and convenient removal and replacement of the entire flexible tube employed in the apparatus, so that a new, sterile tube may be utilized whenever a new container is supplied to the dispensing machine. This has heretofore been in sharp conflict with an object of equal or greater importance, however; that is, to avoid the pulsating or surging characteristics heretofore regarded as inherent in pumps of this general type, since in commercial dispensing apparatus such surging will necessarily result in splashing or splattering as the individual cups are being filled, and such splashing will, of course, contaminate the machine. The present invention thus has, as perhaps the most important object, the reconciliation of these heretofore conflicting considerations, so that characteristics of uniform flow may be gained in a surgical type pump having equally important advantages in sanitation.
A preferred embodiment of the invention is illustrated in the attached drawings, wherein:
Figure l is a front elevational view of a pump as contemplated by the present invention, with the resilient pumping tube and retaining plate therefor removed;
Figure 2 is a front elevational view similar to Figure l, but showing the complete pump structure with tube and retaining plate in place;
Figure 3 is an enlarged front elevational view of the pump, with tube retaining plate removed, showing portions of the pumping tube in cross section to more clearly illustrate the operation of the mechanism;
Figure 4 is a detail sectional view through the pump, taken substantially on the plane of the line 4-4 of Figure 3; and
Figures 5 and 6 are fragmental detail sectional views Z,84,@Z3 Patented Aug. 27, 1957 taken on the planes of the lines 5--5 and 6-6, respectively, of Figure 3.
As illustrated, the pump includes a frame or housing 10 having mounting flanges 11 by which it may be bolted to the underside of any convenient supporting surface. A motor 12 (Figure 4) may conveniently be mounted on studs or posts 13 on the rear surface of the frame 10, and a hub 14 is centrally bored to receive the armature shaft 15 of the motor. The housing 10 thus has its central pump cavity 16 open at the front, with the inner end of the motor shaft 15 projecting into the cavity from the rear. The forward end of the shaft 15 carries a spider 17 having its hub 18 fixedly mounted on the shaft 15 as by a set screw 19. The three arms 21 of the spider are preferably equally spaced from each other, and each arm supports a spring mounted pressure element. These may be the rollers 22 illustrated. As seen in Figures 1 and 4, each of the rollers 22 is carried by a pin 23 at the outer end of one of the bifurcated links 24, pivoted to the individual arms 21 of the spider by pivot pins 25. The rollers are urged outwardly by wire springs 26 coiled upon oppositely paired screw-threaded studs 27. With this arrangement, each of the rollers 22 is individually spring-urged outwardly, to engage the outer walls of the pump cavity 16.
The peripheral walls of the pump cavity 16 are of depth substantially exceeding the diameter of the flexible tube to be used in the pump, and include a. circular track portion 31 against which the rollers bear directly (Figure 4) with a non-circular tube channel 32. The tube channel 32 extends around the outer wall of the pump cavity from the inlet opening 33 of the pump to the discharge opening 34 thereof.
The channel 32 receives a resilient tube 35 in which the pumping action of the device takes place. The tube is readily removable from the pump frame and replaceable therein, however, since it is not permanently secured to the pump, but is held loosely in the channel 32 by a face plate 36 so dimensioned that it overhangs the tube and prevents accidental displacement. Thus when handling milk or other products which must be carefully protected against contamination, a sterilized length of tube may be brought from any suitable source of supply, formed into a loop, and conveniently slipped under the rollers 22 and into the channel 32, with its projecting end portion 37 serving as the discharge spout of the pump.
As best seen in Figure l, the roller track 31 is circular, and extends entirely around the pump cavity 16. The individual pressure rollers 22 may thus bear directly against the track during their cycle of movement. The tube channel 32, however, is of irregular contour including a primary pumping section indicated as zone A and a cam section indicated as zone B, with relatively shorter tangential inlet and outlet portions indicated as C and D, respectively. As shown, the primary zone A encompasses an arc of about and is of uniform depth throughout. Preferably, its depth is slightly less than the thickness of the tube 35 when fully flattened, so that the operation of the rollers 22 moving over the tube in this zone will flatten the tube sufficiently to substantially close it at all points (Figure 5), yet this closing motion will be progressive and constant throughout the zone.
In zone B, the Wall of the tube channel 32 comprises a discharge cam pre-calculated shape, so that the channel (which preferably encompasses an arc of about 120, is of progressively increasing depth throughout. Thus the rollers substantially close the tube at the beginning of this zone, but the flattening action of the rollers becomes progressively less as the depth of the channel increases. It follows that the portion of the tube lying in zone B is subjected to manipulation such as to substantially flatten the tube at the beginning of the zone, yet to accomplish a gradual and pre-calculated reduction in the flattening action throughout the zone. As the rollers 22 approach the end of zone B, they exert less and less effect (Figure 6), until only a superficial flattening action is exerted on the tube at the end of the zone.
The advantages inherent in the type of pump disclosed herein Will be most apparent when it is remembered that the embodiment of the invention illustrated is specifically designed for use in connection with milk vending. machines. In such machines, any possibility of contamination of the milk may be avoided if the pump and other working parts of the vending machines do not at any time contact the fluid being pumped. It follows. that with machines utilizing a pump as here disclosed, the milk may be supplied to the machinesin sealed containers with. individual pumping tubes attached, with the entire assembly ofrcontainer and tube pasteurized and sterilized under closely supervised dairy conditions. Then, when these milk containers. are placed in position in the individual vending machine, the tubes. need only be put inposition in the pump andthe entire milk supply will: be free from danger of external contamination thereafter.
There is no need of opening the milk containers, or in.
any Way contacting the internal surfaces of the tube.
From the foregoing, description, it should be apparent that a pump constructed in accordance with the presentinvention is particularly welladapted to use with a removable and individually replaceable flexible tube. Moreover, the design. and construction of the pump is such that this removal and replacement of the tube may be accomplished quickly, conveniently, and without: fear. of contamination of the fluid being pumped, yet the pump nevertheless provides sufficiently constant displacement: as to give an accuracy of fluid measurement well Within commercially acceptable tolerances. With all of the above, however, the design and construction of the pump is such that the surging, Spurting and spattering heretofore experienced with pumps of this general character are substantially eliminated. The fluid is discharged from the end of the pumping tube in a smooth, quiet, even flow. Obviously, this substantially eliminates the possibility of contamination of the cup port of a dispensing machine by accumulation of droplets of fluid around the cup, and results in a machine more suitable for its intended purposes than those heretofore devised.
Having thus described my invention, What I claim as new and desire to secure by United States. Letters. Patent.
1. In a pump having a generally circular loop of flexible resilient tube and a plurality of pressure rollers rotatably mounted within said loop and tensioned outwardly against the walls of said tube, the combination of a housing having a peripheral wall of width substantially exceeding the diameter of the tube, with a portion of said peripheral Wall of the housingv comprising a roller trackdirectly engaged by the pressure rollers and adapted to limit the outward movement thereof; and a tube channel in said peripheral wall of the pump cavity enclosing said tube; said tube channel havinga" portion of substantial length and of uniform depth throughout to provide a primary pumping zone wherein the portion of tube therein is progressively flattened and substantially closed throughout the zone, with a second portion of the tube channel of length substantially equal to the first zone thereof and of gradually increasing depth; saidsecond portion of the tube channel comprising a secondary zone wherein the tube is subjected to progressively reduced flattening.
2. In a pumping apparatus, a: lengthof flexible resilient tube with a plurality of mechanically driven pressure members arranged to engage and move longitudinally along said tube to flatten said tube: progressively along its length; in combination with tube supporting surfaces uniformly spaced from the path of motion of said pressure members throughout a primary zone in which the tube is periodically and progressively substantially closed, and a secondary zone of decreasing compression including tube supporting surfaces comprising a. discharge cam of length at least equal to the length of the primary zone; said cam coacting with the pressure members for manipulating. the tube in said secondary zone with a progressive action. diminishing from substantially complete flattening at the beginning of said secondary zone to superfi'cial flattening toward the end thereof.
References Cited in the file of this patent