Abstract:
A disposable pump cartridge for use in conjunction with a pump driver characterised in the disposable pump unit containing a pair of piston pumps and inlet and outlet valves positioned at one end of each piston. The piston pump has a pair of pistons arranged for reciprocal motion and which are retained by a retaining mean adjacent the inlet and outlet valves during transit

Description:
[0001]     This application is a continuation-in-part of co-pending application Ser. No. 10/926,491, filed Aug. 26, 2004. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to dispensers in general and more specifically to dispensers for use in beverage and medical applications and pump cartridges therefore.  
       BACKGROUND OF THE INVENTION  
       [0003]     Beverage dispensers for juice, particularly for orange juice, are required to pump a high viscosity juice concentrate and accurately control the ratio of juice concentrate to diluent to produce a beverage of uniform standard. Such dispensers commonly comprise a diluent inlet line from a pressurised diluent source, a juice concentrate reservoir and means for delivering concentrate from the reservoir to the dispenser, which delivering means customarily comprises one of means for pressurising the concentrate reservoir and controlling the flow of concentrate through a valve, means for pumping concentrate from the reservoir and controlling the flow through a valve, or means for volumetrically pumping concentrate from the reservoir. It is known that there are advantages to having a juice concentrate delivery system in which those parts of the system that contact the concentrate are disposable in order to maintain sanitation and reducing the risk of contamination through substandard cleaning of the system.  
         [0004]     To improve sanitation in the delivery of juice concentrate from a concentrate reservoir to a juice dispenser the art contemplates use of a rotary peristaltic pump to deliver the concentrate, a deformable tube of which pump forms an integral part of a disposable concentrate reservoir, and use of a positive displacement pump that includes a disposable piston-type pump portion supplied with the concentrate reservoir and a non-disposable drive for reciprocating the pump to draw fluid into and expel it from the disposable pump, as shown in U.S. Pat. Nos. 5,114,047 and 5,154,319.  
         [0005]     Peristaltic pumps provide a reasonable solution for sanitation problems, but often experience problems pumping higher viscosity fluids such as juice concentrate, and as the viscosity of juice concentrate can be highly dependant on its temperature, peristaltic systems often do not dispense a correct ratio of juice concentrate to diluent at lower temperatures. In addition, the tube part of the pump often deforms to a permanent set over time, such that the volumetric output towards the end of its life is less than that at the beginning of its life, again affecting the ratio of the mix of concentrate to diluent  
         [0006]     Positive displacement pumps, such as that in U.S. Pat. No. 5,114,047, produce a more constant ratio of the mix of juice concentrate to diluent, but because they have a fill cycle and a dispense cycle, the beverage will have a stratified appearance as it exits the dispenser as a result of the concentrate being intermittently dispensed into the diluent stream.  
         [0007]     In medical applications dispensers are often required to dispense medical fluids, for example medications, either at their stored concentration or at a lower concentration. These medical applications exist both at patient care level, i.e. administration of medications directly to patients, for example intravenously, and in other areas, for example in dispensaries. With patients contracting such infections as MRSA whilst in hospital it is important that a high level of cleanliness is maintained in medical equipment and drug administration. Many current medical pumps use a disposable reservoir of fluid and a non disposable pump, the pump being required to be cleaned thoroughly between uses, or before every use in infrequently used equipment This cleaning of the pumps needs a human operation to ensure they are adequately cleaned and such human operation introduces the risk of errors and incomplete cleaning.  
       OBJECT OF THE INVENTION  
       [0008]     A primary object of the invention is to provide a disposable piston pump cartridge suitable for use in a beverage dispenser to pump a beverage concentrate or in a medical application capable of pumping a medical fluid.  
       SUMMARY OF THE INVENTION  
       [0009]     In accordance with the present invention, apparatus for dispensing a post-mix beverage comprises a reservoir of beverage concentrate; a disposable pump unit including a pair of piston pumps having inlet means fluid coupled to beverage concentrate in the reservoir and outlet means; and pump drive means for being coupled to the disposable pump unit for operating the pump unit to pump concentrate from the inlet means to the outlet means. Valves within the disposable pump unit are arranged to enable the pump to prime itself and purge substantially all of the air from pump. Also included is a mixer fluid coupled to the pump unit outlet means; a control valve having an inlet for being fluid coupled to a supply of diluent for the beverage concentrate and an outlet for being fluid coupled to introduce diluent to beverage concentrate intermediate the disposable pump outlet means and the mixer; and control system means. The control system means operates the pump drive means and the control valve to provide a predetermined ratio of diluent to concentrate as delivered to the mixer.  
         [0010]     The invention also contemplates a disposable pump unit for use in a pump suitable for pumping a beverage concentrate, for example in the apparatus described above. The disposable pump unit is also suitable for use in other pumps, particularly in medical applications.  
         [0011]     The invention further contemplates a method of dispensing a post-mix beverage, which method comprises the steps of providing a reservoir of beverage concentrate; fluid coupling an inlet to a pair of piston pumps of a disposable pump unit to beverage concentrate in the reservoir; and fluid coupling an outlet from the pair of piston pumps to a mixer. Also induded are the steps of connecting a pump drive to the disposable pump unit to operate the piston pumps; controlling the pump drive to reciprocate pistons of the pair of piston pumps of the disposable pump unit to pump beverage concentrate from the inlet to the pair of piston pumps to the outlet from the pair of piston pumps; delivering beverage concentrate from the outlet from the piston pumps to a mixer; and fluid coupling diluent for the beverage concentrate from a supply of diluent through a control valve to the beverage concentrate being delivered to the mixer to introduce diluent to the concentrate. Further included is the step of controlling operation of the pump drive and the control valve so that a predetermined ratio of diluent to beverage concentrate is delivered to the mixer.  
         [0012]     The foregoing and other objects, advantages and features of the invention will become apparent from a consideration of the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:  
         [0014]      FIG. 1  is a schematic diagram of a dispenser in accordance with the invention;  
         [0015]      FIG. 2  is a perspective view of a twin barrel syringe pump for use in the invention;  
         [0016]      FIG. 3  is an exploded diagram of a concentrate reservoir, pump and mixing element for use in a dispenser of the invention;  
         [0017]      FIG. 4  is a perspective view of a disposable pump unit of the invention;  
         [0018]      FIG. 5  is a cross section through a disposable pump cartridge of the invention;  
         [0019]      FIG. 6  is a cross section through an alternative pump cartridge of the invention;  
         [0020]      FIG. 7  is a perspective view of a pump cartridge of the invention; and  
         [0021]      FIG. 8  is a perspective view of the rear of the pump cartridge shown in  FIG. 7 .  
     
    
     DETAILED DESCRIPTION  
       [0022]     Referring to  FIG. 1 , a schematic diagram of a beverage dispenser  1  connected to a diluent supply  2 , which may be a supply of mains water. When the diluent enters the dispenser it is cooled in a cooling unit  3  to the required temperature for a beverage, commonly in the region of about 35° F. to 43° F. The cooling unit  3  may be a water bath heat exchanger or other type of cooling technology known in the art, such as a cold plate. An electronic controller  4  receives signals from a diluent flow measurement device (not shown) that may be part of a control valve  5  through which passes cooled diluent from the cooling unit  3 . Electronic controller  4  operates both the control valve  5  and a pump drive  6  in a manner to bring together cooled diluent and juice concentrate in a predetermined ratio for being mixed together and dispensed as a beverage. Situated within or attached to dispenser  1  is a disposable concentrate unit  7 . The concentrate unit  7  comprises a concentrate reservoir  8 , a twin barrel piston pump cartridge  9  driven by the pump drive  6  and connected to and for receiving juice concentrate from the concentrate reservoir  8 , a diluent conduit  10  fluid coupled to an outlet from the control valve  5  for delivering cooled diluent to the concentrate unit  7  for introduction to juice concentrate delivered from the piston pump cartridge  9 , and a static mixer  11  for mixing the juice concentrate and diluent to form a homogeneous mixture.  
         [0023]      FIG. 2  shows an output from the non-disposable pump drive  6  mechanically coupled to the twin barrel piston pump cartridge  9  ( FIG. 1 ). A contemplated embodiment of the twin barrel piston pump  9  comprises two syringe type pump cylinders or barrels  12  and  13  that have associated inlets  14  and  15  fluid coupled to juice concentrate in the concentrate reservoir  8  ( FIG. 1 ). The pump inlets  14  and  15  are provided with respective inlet check valves  16  and  17  that allow flow of concentrate from the concentrate reservoir  8  through the inlets into the pump barrels  12  and  13 , but prevent backflow of concentrate out of the barrels through the inlets. The barrels  12  and  13  also have associated outlets  18  and  19  fluid coupled to the static mixer  11 . The outlets  18  and  19  are provided with respective outlet check valves  20  and  21  that allow flow of concentrate from the barrels through the outlets to the static mixer  11  ( FIG. 1 ), but prevent a reverse flow of concentrate back through the outlets.  
         [0024]     In operation of the concentrate pumping mechanism, a pair of rotary cams  22  and  23  is coupled to an output from the pump drive  6  for being rotated by the pump drive. The cams  22  and  23  are also coupled via interface means comprising associated piston or cam rods  24  and  25  to respective ones of a pair of plungers or pistons  26  and  27  disposed for reciprocation in respective cylinders  12  and  13 . Operation of the pump drive  6  therefore rotates the cams  22  and  23  to reciprocate the pistons  26  and  27  in both directions in the piston pump barrels  12  and  13  to thereby alternatively draw concentrate into the barrels through the check valves  16  and  17  and to eject fluid out of the barrels through the check valves  20  and  21 . The arrangement advantageously is such that the directions of reciprocation of the pistons  26  and  27  through the cylinders  12  and  13  are 180° out of phase, so that while the plunger  26  is being drawn back through the barrel  12  to draw fluid into the barrel through the inlet  14  and the check valve  16 , the plunger  27  is being driven forward through the barrel  13  to expel fluid from the barrel through outlet  19  and check valve  21 . The cams  22  and  23  may be rotated together at a constant speed but, preferably, the rate of rotation of each cam is independently controlled and the speed of rotation is modulated, so that the plungers  26  and  27  are withdrawn through the barrels  12  and  13  at a faster rate than they are driven forward through the barrels, thereby to enable whichever barrel  12  or  13  is not then dispensing fluid to be fully filled with fluid and ready to dispense before the barrel that is then dispensing fluid is at the end of its dispensing stroke. Alternatively this effect may be achieved by rotating the cams at a constant speed and altering the profile of the cam such that the plungers are driven forward at a slower speed than they are withdrawn allowing for an overlap of dispense from each barrel. The result either way is that the twin barrel piston pump  9  delivers to the mixer  11  a substantially constant and uninterrupted output flow of concentrate during a beverage dispense cycle. Other methods of controlling the overlap of the pistons, for example the use profiled cam surfaces, wherein the profile of the cams provides an overlap, driven off a single drive are anticipated and are within the intended scope of the invention.  
         [0025]      FIG. 3  shows a disposable liquid juice concentrate reservoir  28  that is connectable to a disposable twin barrel piston pump element or cartridge  29 . The pump element  29  includes a twin barrel piston pump  30  of a type heretofore described, for pumping the juice concentrate received from the reservoir  28 . A water inlet  31  through which a moderated flow of water is passed from the control valve  5  provides for introduction of diluent to concentrate discharged from the pump  30 . The control valve  5  and the pump drive  6  are operated by the control electronics  4  in such manner as to provide, upstream of a mixer  32 , the bringing together of a predetermined constant ratio of diluent to juice concentrate, depending upon the particular beverage to be served by the dispenser  1 . The concentrate and water diluent are then flowed together through a static mixer  32  to provide a substantially homogeneous mixture of diluted concentrate which is dispensed into a receptacle in a conventional known manner. In the arrangement shown in this  FIG. 3  the disposable twin barrel piston pump  30  has plunger extensions  33  removably connectable to a pump driver, such as the pump drive  6 . The reservoir  28  has an outlet  34  to which one or more inlets to the disposable pump element  29  are connected for receiving concentrate. The reservoir outlet  34  is provided with a protective cap or film (not shown) to cover and seal it during storage and transport It is appreciated that because the drive system reciprocates the pistons  26  and  27  alternately through their pumping strokes in the barrels  26  and  27  of the disposable twin barrel piston pump cartridge  9 , the pump provides a substantially constant and uninterrupted output flow of juice concentrate during a beverage dispense cycle. Also, because the juice concentrate flows primarily through the disposable concentrate unit  7 , which includes the disposable concentrate reservoir  8 , twin piston pump cartridge  9  and static mixer  11 , the juice concentrate comes into contact primarily with disposable parts, so that there are a minimum of non-disposable dispenser parts to be cleaned of juice concentrate, which provides for improved sanitation. When the reservoir of juice concentrate  8  is exhausted, the concentrate unit  7  is simply removed and replaced with a fresh concentrate unit having a full concentrate reservoir  8 , so there is no need to be concerned with cleaning the previously used concentrate reservoir  8 , twin barrel piston pump cartridge  9  and mixer  11 .  
         [0026]     Advantageously, because the pump drive  6  is controllable to operate independently on the two pistons  26  and  27  of the disposable pump element  9  to enable the pump fill cycle to be performed in a shorter time that the pump discharge cycle, provision can be made for a desired amount of overlap in the pumping actions of the two pump barrels, so that there is substantially no perceptible change in concentrate output from the pump as the output flow changes from one barrel to the other. The rotary motion of the cams  22  and  23  as driven by the pump drive  6  is translated into linear motion of the pistons  26  and  27 , such that control of the motion of the pistons can be dictated by control of the relative individual speeds at which the cams are rotated. Alternatively, an arrangement is contemplated where outer ends of the piston rods  24  and  25  would ride on outer peripheral cam surfaces of the cams  22  and  23  (or alternatively in cam tracks on the surface of the cams), in which case the cams could be rotated at the same speed with the speed of fill and dispense of the barrels  12  and  13  of the pump element  9  then being controlled by the profile of the cam surfaces.  
         [0027]     It is understood that the dispenser  1  has a user interface and can be programmed to operate the control valve  5  and the pump drive  6  to either dispense beverages of selected sizes or to accommodate a continuous pour mode in which the dispenser continuously dispenses a beverage until signalled to stop. Preferably the dispenser further includes a sensor to measure the flow of diluent being mixed with the concentrate the pump can therefore be moderated to match the water flow rate and give a constant ratiometric output Alternatively the water flow rate may be controlled to match a desired pump speed and output rate.  
         [0028]     Preferably, an input signal is provided to the control electronics  4  when a new concentrate unit  7  is installed with a full concentrate reservoir  8 , either by means of a user manually inputting a signal, for instance by pressing a reset button, or automatically by identification means on the concentrate unit, for instance an RFID tag on the concentrate reservoir and an associated reader in the dispenser  1 . The input signal would be used to initiate a drinks countdown, such that when there is only a specific amount of concentrate remaining, as determined by the size and number of drinks served, an indication is given to the operator that the concentrate will soon need replacing, with a second signal being sent to the operator when the concentrate reservoir is empty. These signals may take the form of warning lights of different colours or they could comprise a countdown of remaining drinks to be dispensed. In addition, control of the concentrate flow rate can initially be set in accordance with the parameters of the particular concentrate used. Such parameters may be stored in a memory of the control electronics  4  of the dispenser  1  or, alternatively, may be automatically input to the dispenser for each concentrate reservoir as it is installed, for example by means of data stored in a RFID tag or input by an operator manually or via a handheld device.  
         [0029]     Further, while the invention has been described as having the concentrate reservoir  8  and disposable twin barrel piston pump cartridge be part of a single unitary component, i.e., the concentrate unit  7 , it is contemplated that the concentrate reservoir and disposable pump cartridge be supplied as two separate parts which are connected together either immediately prior to or during installation into the dispenser. Preferably, once the disposable pump cartridge  9  and juice concentrate reservoir  8  have been connected they cannot be disconnected, thus preventing reuse of the pump cartridge. However, should the pump cartridge and reservoir be capable of disconnection for reuse of the pump cartridge, then a limitation is placed on the number of times the pump cartridge can be reused.  
         [0030]     Referring to  FIG. 4 , a partially cut away view of a disposable pump cartridge  36  of the invention is shown. The pump cartridge comprises two barrels  38 ,  40  in each of which a piston  42  is arranged for reciprocating movement. The piston  42  is connected to a piston shaft  44  for attachment to a driver (not shown). As the piston is moved in the barrel in direction “A” fluid is drawn into the barrel from fluid inlet  46  via inlet valve  50  which is a simple flap valve, and as the piston  44  is moved in direction “B” the fluid in the barrel is ejected through outlet valve  48  and exits the pump at pump outlet  52 .  
         [0031]     Referring to  FIG. 5 , a cross section through one of the barrels of  FIG. 4  is shown. In use the fluid inlet  56  is connected to a reservoir of fluid (not shown). The barrel has a protrusion  58  in its inner diameter towards the end housing the inlet valve  60  and outlet valve  62 . The piston  64  is movable within the barrel  54 , past the protrusion  58 , between an operative zone  66  and a retained position  68  in which it is retained by the protrusion  58 . When in its retained position  68  a sufficiently high force is required to move the piston  64  from its retained position  68  to its operative zone  66  that it will not easily move out of its retained position  68  as a result of hydrostatic pressures created by the fluid in the reservoir during transit, for example if it were dropped. The piston has piston shaft  70  which has an engagement means  72  by which it can be coupled to a pump driver. The piston  64  and piston shaft  70  are made out of polyethylene or another suitable plastics material.  
         [0032]     Referring to  FIG. 6 , an alternative arrangement of a pump suitable for use in the invention is shown. In this arrangement the piston  74  has a recess  78  centrally located on its face, the recess has a narrow mouth and then opens out into a small cavity. The body of the pump has a protrusion  76  which, at its widest point, is wider that the mouth of the recess  78  on the piston  74 . In use, the piston can be pushed onto the protrusion  76  such that the mouth of the recess deforms allowing the protrusion  76  to enter into the cavity  78 . The piston  74  then substantially elastically recovers its shape around the protrusion  76  retaining the piston  74  in its retained position  80 . The operation of the pump and the engagement and disengagement with the drive system is as described with reference to  FIGS. 3   a - e  and  4   a - e . This design is slightly advantageous in that the retained position  80  is reduced and the operative zone  82  is enlarged. The implications of this is that for the same sized pump more fluid can be pumped per stroke and the amount of fluid left in the dead space in the retained position during normal operation is minimised.  
         [0033]     Referring to  FIGS. 7 and 8 , a detailed view of a disposable pump unit  84  is shown. The unit  84  is manufactured of two parts a body section  86  and a cover section  88 . The body section  86  is a simple plastics moulding and is preferably made of low density polyethylene. The cover  88  is ultrasonically welded to the body section  86  so as to enclose an open face thereof. The body section comprises an inlet  90  connected in use to a reservoir containing the substance to be pumped. The inlet  90  opens into an inlet valving chamber  92  from which two inlet valves  94 ,  96  lead into the end faces of the barrels  98 ,  100  of the pump unit  84 . The pump barrels  98 ,  100  each have a piston therein (omitted or clarity). At the highest most position on the end face of each barrel  98 ,  100  is situated an outlet valve  102 ,  104  leading from the barrels  98 ,  100  into an outlet valve chamber  106 . By placing the outlet valves  102 ,  104  at the very top of the barrels and having them situated above the inlet valves  94 ,  96 , the system is essentially self bleeding as any air within the barrels  98 ,  100  will rise to the top of the barrel and be expelled therefrom via the outlet valves  102 ,  104  and dead space in which air can collect at the top of the barrels is avoided. As the volume of air trapped in any dead space will vary from use to use, ad even from stroke to stroke, good priming and eliminating dead space enables a highly repeatable pump to be effected. The inlet valves  94 ,  96  and the outlet valves  102 , 104  are umbrella or flap type check valves and allow flow in the direction from the inlet  90  to the outlet  108  but not in the reverse direction. The pump unit  84  has a diluent inlet  110  to which diluent can be supplied. Situated in the mouth of the diluent inlet  110  is a diluent check valve  112  to prevent flow of concentrate from the barrels  98 ,  100  into the diluent inlet In addition the check valve operates to prevent drips from the pump via the diluent inlet when the pump is disconnected from the machine. The fluid being pumped, e.g. a beverage concentrate or medication, and the diluent mix in the outlet valve chamber  106  and pass together through a static mixer  114  before exiting the pump unit  84  via the outlet  108 . A protrusion  116  to retain the piston in its retained position during, for example transit (as described in relation to  FIG. 4 ) is shown.  
         [0034]     While embodiments of the invention have been described in detail, various modifications and other embodiments thereof may be devised by one skilled in the art without departing from the spirit and scope of the invention, as defined in the appended claims.