US 3011684 A
Description (OCR text may contain errors)
Dec. 5, 1961 E. R. CORNEIL 3,011,684
LIQUID DISPENSING MACHINE Filed Jan. 15, 1959 yda M QZ 5 M ATTORNEY United States Patent 3,911,684 LIQUID DISPENSING MACI HINE Ernest R. Cornell, RR. 1, Thorold, Ontario, Canada Filed Jan. 13, 1959, Ser. No. 786,593 2 Ciairns. (Cl. 222-214) This invention relates to machines for the sanitary dispensing of liquids in measured quantities.
The automatic vending of food beverages such as milk has been restricted because it has been necessary to prevent contamination of the dispensed beverage. It is essential that the parts of an automatic vending machine for this purpose, which may come into contact with the liquid being dispensed, be non-toxic, free of deleterious effect upon the flavor of the liquid, and subject to easy cleaning and sterilization. Moreover, the manner of sterilization of all contact surfaces must be positive and, so far as possible, not subject to error in the field. Furthermore, the automatic dispensing of food beverages is of intermittent nature and small quantities retained in pumps and piping, generally beyond the cooling zone, deteriorate rapidly. These requirements heretofore have led to the use of tubing of flexible rubber compositions for the final conductor as well as for the measuring means and shut-off valve. Controlling means have usually consisted of rollers driven or dragged along the outside surface of thetubing to pinch it shut at intervals along a fixed track. These rollers move the point of contact on the tubing along with them and deform and knead the tubing materials unnecessarily, which results in use of excessive power and early tube failure. These strains prevent the normal recovery of the tubing to its original circular cross section as a consequence of which less liquid enters behind the point of contact of the rollers and the quantity delivered becomes non-uniform. In addition, the displacement of the wall of the tubing along its axis contributes towards rapid deterioration and early failure thereof. Moreover, since the tubing is not supported between the points of contact, it mayassume a greater than normal internal cross-section and fail in service thereby producing a diflicult cleaning problem and an unsanitary condition. Many moving parts including the journals of a number of rollers, arm pivot points and the like increase the cost of manufacture and the maintenance thereafter. Finally, the active portion of the tubing is not easily and quickly insertable in the present controlling devices, and faulty installation, which may frequently occur, results in nonoperation of the machine and loss of sales.
It is a general object of the invention to provide a simple, positive and economical machine of the flexible tubing type for dispensing predetermined quantities of liquids. Another object is to provide a liquid dispensing machine having improved accuracy of delivery of pro-set quantities of liquid over long time spaced intervals. Another object is to provide a liquid dispensing machine of simplified construction and lower cost of manufacture and maintenance. A further object is to provide a control means for liquid dispensing devices which is drip free and which automatically seals ofl the supply from contamination when in the at rest position.
The invention resides in a liquid dispensing machine comprising a frame an arcuate track mounted on said frame, a cam rotatably mounted in said frame and having a peripheral cam surface, said cam surface being generally circular and having a plurality of circumferentially spaced projections, a section of flexible tubing arranged for disposition between said track and cam surface, said projections be ng arranged to compress said tubing against said track, and means for rotating said cam.
The invention will be described with respect to the accompanying drawing, in which- FIGURE 1 is a side elevation of a liquid dispensing machine in accordance with the invention.
FIGURE 2 is a sectional end elevation on line 22 of FIGURE 1, and
FIGURE 3 is an enlarged sectional View on line 33 of FIGURE 1.
In the drawing, 1 is a base having an upright frame member 2 which carries a hub 3 having a bearing 4 in which a shaft '5- of a cam member 6 is journalled. Cam member 6 has a hub 7, which may be integral with shaft 5. As shown, hub 7 has a tapered socket portion 8 into which hub 3 extends.
Cam member 6 has a substantially cylindrical rim portion 9 supported by spokes 10 from hub 7. -As shown, the rim 9 comprises a plurality of separate sections 11 each having a projecting leading edge 12 and a projecting trailing edge 13 in close proximity and in slightly spaced relation to the leading edge of the adjacent section. Edges 12 and 13 thus lie on the circumference of a circle of greater diameter than that of the exterior arcuate surfaces of sections 11.
Means for driving cam member 6 comprises a motor 14, motor shaft 15, gear 16 fixed thereto, and a mating gear 17 fixed to shaft 5.
An arcuate track 18, which as shown is of semi-circular extent, has one end hinged to frame member 2 at 19. The other end of track 18 has an outturned portion 20 whereby it may be releasably fixed to frame member 2 as by a catch 21 hinged to member 2 at 22 and having a portion 23 arranged to embrace portion 20 of the track, an adjusting screw 24 being provided in portion 2-3. When track 18 is in fixed position with respect to frame member 2, it is concentrically arranged with respect to the opposite portion of the exterior arcuate surface of cam member 6 and in outwardly spaced relation thereto as well as in outwardly spaced relation the circumference of the circle upon which lie the edges 12 and 13.
A flexible curtain 25 has one end anchored to a pin 26 on frame member 2 at a point opposite a lower portion of cam member 6; The curtain 25 has a width which is preferably slightly less than that of rim 9 and it extends about the upper semi-circular exterior surface thereof and in engagement therewith and with the projecting edges 12 and 13. The other end of curtain 25 is not fixed and lies slightly below the opposite lower portion of cam member 6.
The end section of a length of flexible tube of rubber composition or the like is illustrated at 27. The tube 27 is connected to source of supply of liquid beverage (not shown). It will be apparent that, with the track 18 released and swung upwardly about its hinge as shown in dotted lines in FIGURE 1, the end section of tube 27 may be interposed between the curtain 25 and track 18 with a projecting end 28 disposed for entry into a removable container 29 supported on the base. The track 18 is now swung back and locked in fixed relation to the frame by means of catch 21.
The spacing of track 18 from curtain 25, when in fixed position, is such that the portions of tube between the cam projections 12 and 13 and the track will be pinched to close the tube at such areas as clearly shown in FIGURE 2, the intervening portions of tube being in fully distended condition while engaging the curtain 25, and track 18, as'clearly shown in FIGURE 3. Thus, the outer surfaces of cam projections 12 and 13 travel on a diameter greater than that of the exterior circular surface of rim 9 and substantially equal to the inside diameter of track 18 minus twice the thickness of the wall of the tube 27, whereby the pinching action described seals the pinched Wall portions of the tube. There is thus a sealed chamber in the tube between each pair of projections 12 and 13 bearing thereon.
It will be apparent that, on rotation of cam member 6 in a counterclockwise direction as viewed in FIGURE 1, the rim 9 and pairs of cam projections 12, 13 will revolve about the axis of shaft and will successively traverse the curtain 25 from a point of initial engagement adjacent its fixed end to a point adjacent the other end thereof. Such movement will cause the tube to be progressively collapsed at the areas of engagement by the projections 12, 13, i.e., the points at which the wall of tube 27 is pressed together and sealed will move therealong. Since the curtain cannot move circumferentially, the rim 9 with projections 12, 13 will slide along it.
Since the tube is sealed at the areas mentioned, a differential pressure is created between the chambers formed in the tube before and behind the moving area of contact of the tube wall. This pressure is positive ahead of the point of contact of trailing edge or projection 13 and negative behind it. Assuming that the instantaneous position of projection 13 is as shown in FIGURE 1, then that portion of the tube to the right has a negative pressure due to the motion of projection 13 tending to en- 7 large the chamber and the natural resilience of the rubber composition or the like in tube 27 tending to recover its normal shape. It will be apparent that, if this end of the tube were sealed in a fluid, the fluid would be drawn in to fill the chamber. However, to the left of the instantaneous position of projection 13 the pressure is positive and motion tends to shorten the chamber formed in relation to the discharge end 28 of the tube. Liquids contained therein are thus carried along and eventually discharged through the tube end 28.
"With further reference to FIGURE 1, the pressure against the trailing edge 13 is a combination of the resistance of the tube to deformation plus the differential pressure of the liquid in the tube. This varies in part with the speed of rotation. The sum of these pressures tends to force the trailing edge 13 away from its proper position with respect to track 18. However, the pressure ahead of trailing edge 13 within tube 27 tends to enlarge the cross-section thereof and is restrained by leading edge 12 and its support resulting in the balancing of forces applied to rim 9 on the spokes 10.
It has been found that a most favorable operation is obtained when the distance from the junction of a spoke 10 with a rim section 11 to the leading edge 12 thereof is approximately five times the distance of such junction to the trailing edge 13 thereof. The turning moment of hub 7 and transferred to the rim sections 11 and their leading and trailing edges 12, 13 is transferred to the curtain 25 and resisted by the anchor 26 so that tube 27 does not have to resist this moment and transfer it, at least in part, to the track 18. Thus, the strain which heretofore has caused rapid failure of the tube is eliminated by transfer to the curtain 25. Moreover, this strain which in former machines reacted against the natural resilience and recovery of the tube is eliminated and cannot affect the uniformity of the recovery. Therefore, the volume of the chamber under negative pressure remains constant and the uniform volume of liquid received results in equal deliveries in relation to time over long periods.
Means for controlling rotative movement of cam member 6 comprises a main switch 30 in the power circuit 31 of motor 14. It will be apparent that a suitable switch may be employed. For instance, it may be a time switch which when closed remains so only for a timed interval. Thus, when switch 30 is closed, current fiows to the driving motor and continues to flow for a specific time interval, say, 30 seconds. At a constant speed, the cam member 6 will then make a specific number of revolutions and, since there are four sets of cam projections 12, 13, four times the contents of each chamber between the cam projections will be delivered for each revolution. Adjustment of the rate of revolution and the time interval that the switch is closed will 4 of course proportionately adjust the volume delivered.
Means are preferably provided for defining a predetermined shut down position of the cam member 6. Such shut down position will desirably be that shown in FIGURE 1 with a pair of cam projections 12, 13 in adjacent relation to the hinged end of track 18. Such means, as shown, comprises a switch generally indicated at 32 and including a fixed contact 33 mounted on frame member 2 as by bracket 34 and a movable contact 35 mounted on a spring arm 36 carried by bracket 37 fixed to frame member 2. Spring arm 36 normally holds contact 35 in engagement with contact 33 to close the switch. However, spring arm 36 is positioned for successive engagement by each leading edge 12 as it approaches its approximate lowermost position of travel whereby arm 36 is depressed thereby to move contact 34 out of engagement with contact 33 and open the switch. It will be observed that such switch opening will occur at the previously mentioned shut down position. With switch 30 closed power is supplied and rotation will commence and continue even after switch 30 is opened but only until the leading edge 12 of the passing section 11 presses contacts 33 and 35 apart and cuts off the power. Thus, cam member 6 will stop in the mentioned shut down position. The portion of tube 27 extending beyond the pressure point adjacent the discharge end of the tube is of limited length so that the contents drain quickly and there is substantially no drip. However, since the pressure point produces a seal, the liquid in the tube is sealed therein and protected from contamination.
The positive sealing off of the flow in the dispensing of food beverages is important for sanitary reasons as previously stated but it is also important that there should be a minimum of loss due to failure of the equipment or to intentional pilfering. The device of the present invention lends itself to the maximum of protection in this regard. Thus, should the tube fail in service or be deliberately punctured, no liquid would leak from the supply reservoir since the latter may readily be placed below the dispensing machine. Operation of the present device is such that negative pressure created within the tubing is suficient to initiate and maintain the flow of liquid from a source several feet below the dispensing machine.
Since the machine of the present invention is of simple mechanical form and has relatively few parts and only a single journal, its cost of manufacture and maintenance is considerably reduced.
The curtain 25 must be freely flexible such that it will readily flow around the curvature produced by the cam projections. The curtain must also have a minimum of stretch. Thus, the curtain should be formed of a material having strong longitudinal fibres such as a plastic composition material having the molecules oriented parallel with the length of the curtain. A preferred example of a suitable material is a woven tape of drawn filaments of tetrafluoroethylene, which is known under the trade name Teflon.
The curtain 25 serves two essential purposes: it must resist the turning moment created by the rotor assembly and it must slide under pressure over hard polished metal surfaces as presented by the surfaces of rim sections 11 with the cam projections 12, 13 with or without lubricants. It will be appreciated that a cotton curtain will operate if lubricated in a conventional way but does not have the same degree of preference as the example previously given. Another example of an operable form of material for the curtain is a flat metallic chain having an anti-friction surface.
The following table gives the results of tests conducted with a machine of the present invention using a rubber composition tubing formulated for the dispensing of milk and approved by Government authorities and having Z5 inch outside diameter and a wall thickness of 0.070 inch.
Revolutions per minute Ounces per second 1. A liquid dispensing machine comprising a frame, an arcuate track mounted on said frame, a cam rotatably mourned in said frame and comprising a cylindrical rim member having a plurality of separate sections, and a radial spoke separately supporting each said section, each said section having a major arcuate portion, said arcuate portions lying in a common circular path, a leading edge and a trailing edge each extending radially outwardly from and in fixed relation to said arcuate portion, said sections being circumferentially spaced to space the leading edge or" each said section from the trailing edge of the succeeding section, said leading edges terminating in a common circular path, said trailing edges terminating in a common circulm path, each said section being supported by said spoke at a point several times closer to the trailing edge thereof than to the leading edge thereof, a section of flexible tubing arranged for disposition between said track and cam, a flexible curtain interposed between said cam and said tubing, said curtain having one end fixed to said frame for slidable engagement by said cam in response to rotation thereof, said arcuate portions being in engagement with said curtain from end to end thereof, said leading and trailing edges being radially spaced from said track a distance approximately equal to double the thickness of the Wall of said tubing whereby said tubing is fully collapsed by said edges in the areas of engagement thereby, said means for rotating said cam.
2. A liquid dispensing machine as defined in claim 1, each said section being supported by said spoke at a point several times closer to the trailing edge thereof than to the leading edge thereof.
References Cited in the file of this patent UNITED STATES PATENTS 1,596,933 Kister et a1. Aug. 24, 1926 2,123,781 Huber iuly 12, 1938 2,476,346 Acosta July 19, 1949 2,483,924 Moulinier Oct. 4, 1949 2,668,637 Gilmore Feb. 9, 1954 2,695,117 Daniels Nov. 23, 1954 2,696,173 Jensen Dec. 7, 1954