Abstract:
A beverage dispenser for dispensing a post-mix beverage is characterized by a disposable concentrate beverage unit and a disposable pump unit that are housed in a refrigerated area of the beverage dispenser. The pump unit is operable to dispense metered volumes of concentrate for mixing with a regulated flow of diluent to dispense a required ratiometric mixture thereof.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to beverage dispensers and more especially relates to beverage dispensers having disposable diaphragm type pumps. 
       BACKGROUND OF THE INVENTION 
       [0002]    Beverage dispensers commonly provide a ratiometric mixture of a beverage concentrate and a diluent and this is commonly done by regulating the flow of two pressurised sources of concentrate and diluent. However, some concentrates are highly viscous and do not flow easily, a problem which is enhanced at the low temperatures at which they are stored. The variance in viscosity means that it is hard to accurately meter a pressurised flow of viscous concentrates, for example orange juice concentrate, and to do so effectively requires a pressure much higher than is conventionally used. This problem is overcome to some degree by current juice dispensers which utilise a positive displacement pump to pump the concentrate and regulate the flow of diluent accordingly. 
         [0003]    Another problem associated with the viscosity of some concentrates is that they do not readily mix with a diluent, for example water. This has two adverse effects. The first is that when the beverage is dispensed into a receptacle for consumption, there is often found a slug of unmixed concentrate at the bottom of the receptacle, which is unappealing to the consumer. Secondly, due to the viscosity and high sugar content of juice concentrates, the concentrate will tend to adhere to the internal components of the dispenser and is not easily cleaned by simple rinsing. This is particularly relevant for example, with orange juice concentrate, which can become highly toxic through bacterial growth if allowed to sit for long period of time at room temperature. A common contributory factor to these two problems is the non disposable part of the machine through which the concentrate (diluted or undiluted) passes. 
         [0004]    There are three systems known in the art which provide a more sanitary system for dispensing concentrate by use of partially disposable components. Two of these are use of a rotary peristaltic pump, the deformable tube of which forms an integral part of the disposable concentrate reservoir, and a positive displacement pump comprising a disposable portion supplied with the reservoir and a non-disposable drive to reciprocate the pump, drawing fluid into, and expelling it from, the disposable portion, as shown in U.S. Pat. Nos. 5,114,047 and 5,154,319. 
         [0005]    There are several problems associated with these designs, including problems with pumping high viscosity concentrates, long term permanent deformation of peristaltic tubes, inadequate mixing of concentrate and diluent and “streaming”, which is the visual effect of seeing stratification of concentrate and diluent as the beverage is dispensed. 
         [0006]    A third solution has been proposed in EP 1 716 068, which comprises a disposable membrane pump driven by application of pressure and vacuum to the diaphragm to pump the concentrate. This solution overcomes many of the problems associated with previous designs, but has limitations. In particular, if the dispense is stopped part way through a dispense cycle, i.e., when a pump chamber is partially dispensed, it is not possible to easily determine how much concentrate has been dispensed from that pump chamber. The result of this is that it is virtually impossible to reliably get an exact ratiometric mix of concentrate to diluent when the dispense is stopped with a partially empty pump chamber. This problem is amplified when only dispensing a small amount, for example in a mixed drink (e.g., vodka and orange juice). In addition, the use of pressure and vacuum pumps and all the associated valving creates an overly complex solution needing a detailed control system that has many potential failure modes. 
       OBJECT OF THE INVENTION 
       [0007]    A primary object of the present invention is to provide an improved sanitary beverage dispenser having a diaphragm pump and which mitigates some of the problems with known systems. 
       SUMMARY OF THE INVENTION 
       [0008]    According to the present invention, there is provided a beverage dispenser for dispensing a post-mix beverage from a disposable concentrate pump unit comprising two inlet valves, two pump chambers having a flexible membrane and two outlet valves, the dispenser comprising a diluent supply system to supply a flow of diluent to a section of the disposable pump unit; a cabinet area for receiving at least one reservoir of concentrate; and at least one pumping station for receiving, retaining and actuating a disposable pump unit. The pumping station comprises a drive plunger associated with each pump chamber and arranged for reciprocal movement to displace the flexible membrane in a first direction to expel concentrate from the pump chambers and in a second direction to draw concentrate into the pump chambers; and vacuum means for applying a pressure differential across the flexible membrane when a drive plunger is moving in its second direction, so as to cause concentrate to be drawn into the pump cavity as the plunger is withdrawn. 
         [0009]    In a contemplated embodiment of the invention, the negative pressure differential across the flexible membrane when a drive plunger is moving in its second direction maintains the membrane in contact with the drive plunger as concentrate is drawn into the pump chambers. Each drive plunger is driven by a cam, and the cams are profiled such that movement of a drive plunger in the second direction is faster than movement of the plunger in the first direction, resulting in concentrate being drawn into a pump chamber in a shorter time interval than it is expelled from the pump chamber. 
         [0010]    Each pump chamber has a dedicated vacuum means and a conduit leading from the vacuum means to the outer side of the flexible membrane, and the disposable concentrate pump sealingly engages with the pumping station to form an enclosed area between each pump chamber and the pumping station. Preferably, each vacuum means comprises an enclosed chamber having a vacuum pump inlet valve and a vacuum pump outlet valve, the vacuum pump inlet valve being in the conduit between the vacuum means and the outer side of the flexible membrane; and a vacuum drive member movable in the enclosed chamber in a first direction to draw air through the vacuum pump inlet valve and in the other direction to expel air from the enclosed chamber, thereby creating a pressure differential across the flexible membrane. The vacuum pump inlet and outlet valves may be check valves. 
         [0011]    Each conduit passes into and through the drive plunger, terminating at an opening in the end of said plunger which, in use, displaces the flexible membrane. Each vacuum drive member is driven by a cam, and the vacuum drive member cam and drive plunger cam for each pump chamber are driven by a common drive shaft. The drive shafts for each pump chamber are driven simultaneously by a single motor. 
         [0012]    Each of the concentrate pump inlet valves comprises a flexible membrane overlaying an inlet orifice, and the pumping station further comprises an inlet valve plunger associated with each inlet orifice and arranged for reciprocal movement to displace the flexible membrane in a first direction to cover and close the inlet orifice, thereby preventing flow of concentrate therethrough, and in a second direction to allow the membrane to move away from the orifice and allow concentrate to pass therethrough. Each inlet valve plunger is driven by the common drive shaft by means of a cam. 
         [0013]    In a contemplated arrangement, each of the concentrate pump outlet valves comprises a flexible membrane overlaying an outlet orifice, and the pumping station further comprises an outlet valve plunger associated with each outlet orifice and arranged for reciprocal movement to displace the flexible membrane in a first direction to cover and close the outlet orifice, thereby preventing flow of concentrate therethrough, and in a second direction to allow the membrane to move away from the orifice and allow concentrate to pass therethrough. Each outlet valve plunger is driven by the common drive shaft by means of a cam. Alternatively, each outlet valve is a check valve. 
         [0014]    Where present, each valve cam is profiled to open the valve quickly and to maintain it in its open position as the pump chamber fills with, or expels, concentrate, and to then close the valve quickly. The pumping station actuates the two sets of inlet valves, pump chamber and outlet valves out of phase with each other. Advantageously, the flow of concentrate expelled from each of the pump chambers overlaps one another so that, in use, concentrate is constantly expelled from the concentrate pump. 
         [0015]    The diluent supply system may comprise a flow meter to measure the flow of diluent passing therethrough, and the rate of pumping concentrate may be controlled to be dependant on the flow of water being supplied to the pump, which may be accomplished by controlling the speed of a motor for a concentrate pump to be dependant on the measured flow of water. Desirably, the flow of water is set to a desired flow rate. 
         [0016]    The foregoing and other objects, advantages and features of the invention will become apparent from the following detailed description, when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a schematic diagram of a beverage dispenser in accordance with the teachings of the present invention; 
           [0018]      FIG. 2  shows a disposable pump cartridge suitable for use with the dispenser; 
           [0019]      FIG. 3  shows an alternative pump cartridge suitable for use with the dispenser; 
           [0020]      FIG. 3   a  is a cross section of a valve for use in the pump cartridge of  FIG. 3 . 
           [0021]      FIG. 4  is a diagram of a dispenser in accordance with the invention; 
           [0022]      FIG. 5  is a diagram of a dispenser in accordance with the invention with the front cover open and the retainer plates open; 
           [0023]      FIG. 6  is a diagram of a disposable reservoir and pump unit for use with the invention; 
           [0024]      FIG. 7  shows a perspective view of a pumping station in accordance with the invention with a pump cartridge presented to it; 
           [0025]      FIG. 8  shows a perspective view of a pumping station in accordance with the invention; 
           [0026]      FIG. 9  shows a top view of a pumping station in accordance with the invention; 
           [0027]      FIG. 10  shows a section view on “A-A” of  FIG. 9 ; 
           [0028]      FIG. 11  shows a valve plunger and associated cam; and 
           [0029]      FIG. 12  shows a cam profile suitable for driving a drive plunger; 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    Referring to  FIG. 1 , a schematic diagram of a beverage dispenser is shown in which a beverage dispenser  2  is connected to a diluent supply  4 , which may be a continuous supply, for example a supply of mains water. An adjustable valve  6  controls the flow of the diluent through the dispenser. Normally, the flow through the valve  6  will be set below the maximum flow the supply  4  is capable of supplying to ensure there is always sufficient flow. The flow of the diluent is measured using a flow turbine flow sensor  8 . After passing through the flow sensor  8 , the diluent is cooled in a cooling unit  10  using a water bath heat exchanger which comprises an outer coil through which a refrigerant passes, cooling the water and forming a bank of ice surrounding the refrigerant coil, the ice bank maintaining a constant temperature within the water and a reserve of cooling energy to maintain that temperature. In the liquid phase of the water bath is a secondary coil through which the water or diluent passes, cooling as it does so to a temperature commonly in the region 1 to 6 degrees centigrade. Control electronics  12  receive signals from a flow sensor and control the speed of a motor  14  to adjust the dispense rate of concentrate from a disposable concentrate unit  16  situated within or attached to the dispenser  2  and comprising a concentrate reservoir  18 , a dual-cavity pump unit  20  connected to the concentrate reservoir  18 , a connection  22  for diluent conduit  24 , and a static mixer  26  to mix the concentrate and diluent to form a homogeneous mixture. 
         [0031]    Referring to  FIG. 2 , a rigid plastic pump cartridge is shown and comprises a fluid inlet  28  leading to two chamber inlet ports  30  from which there is a flow path to the concave cavity  32  and its associated chamber outlet  34 . Provided in surface of the concave cavity  30  and a flat area  36  are recessed grooves  38  which, should the flexible film (not shown) that covers the pump cartridge and is welded to a surface  39  trap an occluded area of the pumped fluid remote from the chamber outlet  34 , will always provide a channel for the fluid to be forced out of to ensure that the chamber is fully emptied every time, thus giving a repeatable volumetric output from the pump cartridge. The pump cartridge has had all excessive plastic removed and designed for production by injection moulding techniques from polyethylene. The pump cartridge further comprises an integrated static mixer  40 , which is formed as a feature of the plastic moulding enclosed by flexible film which is heat welded thereover. Additionally, an array of obstructions  42  are provided between a pair of outlet ports  44  and the static mixer  40 , such that fluid is sheared immediately prior to it admixing with the diluent entering via diluent inlet  46 . Once admixed with the diluent, the fluid passes through the static mixer  40  and is dispensed therefrom as a homogeneous fluid. In the fluid inlet  28  is a closure  48  that is rotatable by means of a lever  50  to open or close the flow from the reservoir (not shown) to the inlet ports  30 . In use, movement of the flexible film draws concentrate into the concave cavities  32 , which in combination with the flexible film form pump cavities, and expels it therefrom via the outlet orifices  44  where it mixes with diluent entering via diluent inlet  46  before passing therewith through the static mixer  40  before exiting the pump cartridge as a diluted beverage. In use, the flexible film is moved on and off the inlet orifices  30  and the outlet orifices  44  by a mechanical means (described below) so as to allow, or obstruct, flow therethrough. The flexible film over the pump cavities  32  is displaced away from the cavities  32  by a vacuum means (described below) to draw concentrate through inlet orifices  30  into the pump cavities and is displaced by mechanical means (described below) to expel concentrate from the pump cavities  32  via outlet orifices  44 . 
         [0032]    Referring now to  FIG. 3 , the same pump cartridge is shown as in  FIG. 2 , except that it is additionally provided with check valves  52  in the outlet orifices  44 , which allow flow in the direction from the pump chamber towards the static mixer, but prevent flow in the opposite direction. The check valves  52  are “umbrella” valves made of an elastomeric polymer, but any known alternatives may be used. By using these check valves  52 , the need for mechanical closing of the outlet orifices  44  is removed. 
         [0033]    Referring to  FIGS. 4 to 6 , a dispenser  54  is shown with a user interface  56  to allow the user to select to dispense a beverage. A door  58  of the dispenser opens to allow the user to load and unload a disposable concentrate unit  60 . The disposable concentrate unit  60  consists of a flexible reservoir (not shown) connected to a dual cavity pump unit  62  which has a diluent inlet  64  and a static mixer  68 . The flexible reservoir is placed within a re-usable rigid container  70  that supports the flexible reservoir. Diluent enters the pump unit  62  downstream of the cavities which pump the concentrate and the pumped concentrate and diluent then flow together to the static mixer  68 , which uses turbulence and fluid shear as the admixture passes therethrough to produce a homogeneous mixture. 
         [0034]    The disposable concentrate unit  60  and disposable pump unit  62  are placed in the dispenser  54 , such that both are within the refrigerated area  72  of the dispenser  54 , and the pump unit  62  is positioned such that it interfaces with the pumping station  74 , of which two are situated within the dispenser  54 . By maintaining both the pump unit and the reservoir in the refrigerated section, any juice within the cavities of the disposable pump unit is maintained at its refrigerated temperature. The re-usable rigid container is preferably of a two part hinged construction for ease of use and may optionally have an angled lower surface (not shown) to aid the concentrate to drain, under the influence of gravity, towards the disposable pump unit  64 . An angle of the surface of approximately 15 degrees was found to be most beneficial. The upper refrigerated cabinet area is cooled by means of a standard air blown refrigeration system as known in the art. The dispenser  54  has a drip tray  76  positioned below the point of dispense to retain any drips from the static mixers  68 . 
         [0035]    Referring to  FIGS. 7 to 11 , a pumping station  76  is shown for pumping juice from a pump cartridge as shown in  FIG. 2 .  FIG. 7  shows the pumping station  76  with a cartridge  78  presented to it. In use, the cartridge  78  would be clamped into place against the pump station  76  and a diluent supply is supplied to the cartridge  78  at diluent inlet  80 . In use, the concentrate inlet  82  is connected to a concentrate reservoir as shown in  FIG. 6 .  FIG. 8  shows the same arrangement of pumping station  76  with the cartridge removed. The pumping station  76  has a face plate having a face  84  to which the cartridge is presented. The face has a seal  86  on it that seals between the cartridge  78  and the pumping station  76  around the periphery of the pump chamber of the cartridge. The face  84  has two recesses  88  therein, surrounded by the seal  86 . In use, the flexible diaphragm covering the pump cavity of the cartridge  78  moves from a position in which it lies in the pump cavity when said pump cavity is empty to a position in which it extends out into the recess  88  in the face  84  when the pump cavity is full of concentrate. Extendable into each recess  88  is an inlet valve plunger  90  and a drive plunger  92 . In use, the valve plunger  90  moves into the recess to press the flexible film onto the rim of the inlet orifice ( 30   FIG. 2 ), thereby closing it, and out of the recess to allow the film to move off the inlet orifice, thereby allowing it to open. The drive face  84  further has two outlet valve plungers  94  extendable therefrom. The outlet valve plungers operate in the same way as the inlet valve plungers to move the film on and off the outlet orifices ( 44   FIG. 2 ). The valve and drive plungers are driven by a mechanical drive linkage driven by a motor  96 , as described below. 
         [0036]    The mechanical drive linkage comprises two identical drive shafts  98  with associated components, each of which drives one set of inlet valve plunger, drive plunger and outlet valve plunger. The two drive shafts  98  are simultaneously driven through a bevel gear system  100  by a single motor  96 . Each drive shaft has mounted to it four cams, each of which drives a different element of the pumping station. The uppermost cam  102  of each drive shaft  98  drives the inlet valve plunger. It is a follower cam and the outlet plunger  90  is maintained in contact with it by means of spring  104 . The cam  102  acts against a roller  106  and moves the inlet valve plunger  90  into and out of the recess  88 . The cam profile is such that it is in its withdrawn state (when the valve is open) for a shorter time than it is in its extended state (when the valve is shut). This enables the pump chambers to fill with concentrate in a shorter time than they empty the concentrate, enabling an overlap of concentrate output from each pump chamber to be achieved resulting in a substantially constant output form the cartridge  78 . The second cam  108  is also a follower cam and moves the drive plunger  92  into and out of the recess  88 . The drive plunger  92  has two follower rollers  110 ,  112  opposed to one another across the cam in the direction of plunger travel, thus the drive plunger  92  is driven in both directions by the cam. The third cam  114  drives the outlet valve plungers  94  and acts with spring  116  and roller  118  in the same way as the inlet valve cam and substantially 180 degrees out of phase with it. The cam  114  profile, however, is different and is profiled such that the valve open time is longer that the valve closed time. The forth cam  120  drives a small vacuum pump comprising vacuum plunger  122  and vacuum cavity (the cavity can not be seen in the drawings as the vacuum plunger  122  is in its fully extended position completely filling the vacuum cavity). The cam  120  has the same profile and acts in the same manner, with two rollers  124 ,  126 , and in phase with the drive plunger  92  to reciprocate the vacuum plunger  122  in and out of the vacuum chamber. A vacuum conduit  128  passes through the vacuum plunger  122 , through a connecting conduit  130 , and then through the drive plunger wherein it splits and opens through ports  132  at the driving face thereof. The drive shafts are each held in captive by four bearings  134  in which they rotate. 
         [0037]    In use, starting from the position shown in the drawings and in relation to the valve-pump-valve arrangement in the  FIG. 10 , in its initial position both valves are closed and the drive plunger  92  is in its position extended into the recess  88 , so the pump cavity is substantially empty. As the drive shaft  98  rotates in an anticlockwise direction, the inlet plunger  90  is withdrawn from the recess  99 , thereby opening the inlet valve. Simultaneously or very shortly thereafter, the cams  108  and  120  act on the drive plunger  92  and the vacuum plunger  122  respectively, withdrawing them in unison. As the vacuum plunger is withdrawn, a vacuum is created in the vacuum chamber. This vacuum is conveyed by means of conduits  128  and  130  through the ports  132  to create a vacuum adjacent the flexible film of the pump cartridge  78 . This vacuum draws the film towards the drive plunger  92  as it is withdrawn, causing concentrate to be drawn through the inlet orifice ( 30   FIG. 2 ) of the pump cartridge  78  and to fill the pump chamber. When the drive plunger  92  is fully withdrawn, the continuing rotation cams  102  and  114  attached to the drive shaft  98  causes the inlet valve to close and the outlet valve to open. As the outlet valve opens, or shortly thereafter, cams  108  and  120 , by their continuing rotation, reverse the direction of the drive plunger  92  and the vacuum plunger  122 . As the drive plunger  92  moves forwards, it expels concentrate from the pump cavity through the outlet orifice ( 44   FIG. 2 ), whereafter it mixes with a diluent entering the cartridge  78  via diluent inlet  80 . The diluent and concentrate then pass through a static mixer, which is integral with the cartridge  78 , and exit therefrom for consumption. Check valves, not shown, vent any air within the vacuum chamber out to atmosphere, thereby allowing, in operation, a permanent pressure differential to be effected across the flexible film of the pump cartridge  78 . By maintaining this pressure differential, the position of the film can be maintained constant as the drive plunger  92  is reciprocated, thereby maintaining a dispense which is predictably related to the displacement of the drive plunger  92 . This enables the mechanism to be stopped in any position and the ratiometric mix of a dispensed beverage will remain constant. 
         [0038]    The two drive shafts  98  and associated components operate so as to drive the two sets of valve-pump-valve plungers substantially out of phase with one another. However, as the inlet valve is open for less than half of the cycle and the outlet valve is open for more than half of the cycle, there will be an overlap in the output of concentrate from the two pump chambers of the valve. This will give a substantially constant output of concentrate resulting in a ratiometric mixture of the dispensed beverage that is substantially constant independent of where in the cycle the dispense apparatus is stopped. 
         [0039]    Referring to  FIG. 12 , a cross section of a pumping station is shown for use with the pump cartridge shown in  FIG. 3 . Essentially, this is identical to the pumping station shown in  FIGS. 7 to 11 , except in so much that as the pump cartridge of  FIG. 3  has internal check valves on the outlet, the outlet valve plungers are not needed as the outlet valves no longer need external actuation. In this embodiment, there are only three cams on the drive shaft  136 , a top cam  138  to drive the inlet valve plunger  140 , a middle cam  142  to drive the drive plunger  144  and an lower cam  146  to drive the vacuum plunger  148 . In all other respects the pumping station functions and pumps in the same way as described above. 
         [0040]    Modifications of the invention, for example the replacement of the cam driven vacuum pump with a separate vacuum pump or combinations with any of the many known features of beverage dispensers, will be obvious to those skilled in the art and are within the scope of the invention.