Abstract:
A microprocessor-controlled beverage dispenser is disclosed, which provides a cold plate having disposed therein beverage lines and refrigerant lines. The refrigerant lines may be connected to a cooling or refrigeration system, including a heat exchanger. The beverage lines may be connected to a beverage supply for dispensing a desired beverage. Valves and pressure sensors in the refrigerant line are engaged with a microprocessor. If the temperature falls below a desired value, then the cooling system is shut off. This permits the microprocessor to closely control the temperature of the beverage being dispensed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 12/716,949, filed on Mar. 3, 2010, which claims priority to and the benefit of U.S. provisional application 61/157,031 filed Mar. 3, 2009. This and all other referenced extrinsic materials are incorporated herein by reference in their entirety. Where a definition or use of a term in a reference that is incorporated by reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein is deemed to be controlling. 
     
    
     BACKGROUND 
       [0002]    This application incorporates by reference both U.S. Provisional Patent Application Ser. No. 61/157,031 and U.S. Pat. No. 7,296,428, issued Nov. 20, 2007, to the extent that the specifications of these do not conflict with the specification set forth herein. 
         [0003]    The device disclosed is related generally to beverage dispensing systems employing a cooling subsystem, more particularly, a self-contained tabletop beverage dispenser incorporating a refrigerant chilled cold plate for cooling a beverage. 
         [0004]    When beer (or other beverage) is charged with a gas, such as a carbon dioxide, to move the beer through the various lines, the gas is entrained to dissolve in the fluid and resides in a stable state for temperatures at or below about 30° F. The gas typically does not bubble out of the fluid, but is carried in the fluid and gives a beverage a distinctive effervescence when consumed. However, as the temperature of the beer rises above about 30° F., absent increase in pressure on the system, the gas becomes increasingly unstable and begins to bubble or foam out of the flowing beer. Further warming of the beer increases the foaming effect, as the gas bubbles form and propagate downstream. Foaming is further exacerbated by disturbances in the beer, such as the turbulence generated when the beer is dispensed from the dispensing valve. When beer is warmed to 45° F. or more, such as when exposed to normal ambient room temperature, the gas becomes sufficiently unstable and so much foam is generated when it is dispensed that it often cannot be served to patrons. As a result, as waste increases, and profits decrease. 
       OBJECTS OF THE INVENTION 
       [0005]    One of the objects of the present invention is to prime a refrigeration system for restarting at a later time by drawdown on the suction end before the compressor is turned off. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is directed to a beverage dispensing system for dispensing chilled beverages, the system comprising a housing with one or more beverage inlet connections extending from said housing and one or more beverage dispenser valves extending from said housing. A beverage cooling system is positioned within said housing, said cooling system comprising a reservoir capable of receiving a supply of refrigerant, a cold plate in fluid communication with said refrigerant reservoir, wherein the refrigerant lines extend through said cold plate, wherein beverage lines also extend through said cold plate adjacent to said refrigerant lines. 
         [0007]    The cooling system further includes an accumulator, a compressor, a refrigerant condenser, and a thermal expansion valve positioned between said refrigerant reservoir and said cold plate to adjust the flow of refrigerant depending upon the temperature of the cold plate. 
         [0008]    If freeze-up of the beverage in the beverage lines occurs, refrigerant may be controlled by means of a hot gas valve to divert the flow of refrigerant from the cold plate, adding hot gas from the high side of the compressor to the cold plate refrigerant inlet line. Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints and open-ended ranges should be interpreted to include only commercially practical values. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary. 
         [0009]    A beer or beverage evaporator valve, typically a solenoid, is provided upstream of the accumulator and downstream of the cold plate. A liquid line valve is provided typically downstream of the condenser and upstream of the reservoir, also solenoid controlled. A thermal expansion valve is provided downstream of the reservoir upstream of and close to the refrigerant inlet of the cold plate, for metering refrigerant into the cold plate in response to a thermal bulb at the outlet of the refrigerant lines on the cold plate. 
         [0010]    Electronic sensors, such as transducers (including thermal or pressure sensors), may be provided in conjunction with a microprocessor to control the operation of the system. In one embodiment, a temperature sensor (such as a thermistor) or pressure transducer is located upstream of the evaporator valve and a pressure transducer is located near the suction or low side of the compressor. When the system is energized, that is, in a “run” or “on” mode, the microprocessor will control the compressor. The microprocessor, responsive to the evaporator (cold plate) condition, will initiate a system shutoff when a predetermined psi, for example approximately 55 psi, is reached. The first step of the system shutoff will be to de-energize the normally closed beer evaporator and liquid line valves (thus closing them), thus “trapping” the refrigerant between the valves and in the evaporator and begin monitoring of the sensor at the low end of the compressor or suction side, continuing the compressor running until a predetermined pressure, for example about 10-35 psi, is sensed (thereby assuring the accumulator is void of liquid). At a compressor low end of 10-35 psi, the compressor de-energizes and the system will wait again for a signal from the transducer just downstream from the evaporator. When this transducer hits 70 psi or the associated temperature, the microprocessor will initiate an “on” command to the compressor will be turned on and the solenoids will be energized and opened. 
         [0011]    Restated, the microprocessor, in response to a high set point (cold plate too warm) from the first transducer (just upstream of the beer evaporator valve and downstream of the cold plate), will energize the compressor and open the liquid line valve and the evaporator valve, and responsive to an intermediate set point (cold plate low temperature) from the first transducer will close the liquid line valve and evaporator valve, but keep the compressor going, and in response to a low set point from the second transducer (accumulator dry), de-energizes the compressor and goes back to begin the cycle, monitoring the first transducer for the high set point. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  is a perspective view of the tabletop unit showing the housing, the beverage outlets, and the spill tray. 
           [0013]      FIG. 2  is an equipment layout, not to scale, showing the relative positions of the elements of Applicants&#39; novel beer cooling system. 
           [0014]      FIG. 2A  is a block diagram illustrating the microprocessor inputs and outputs. 
           [0015]      FIGS. 3 and 4  are perspective view of the equipment layout showing the elements of the cooling system in place with the housing cover removed therefrom. 
           [0016]      FIG. 5  is an elevational view of the beverage or beer lines and refrigeration lines within the cold plate. 
           [0017]      FIG. 6  is a perspective view of a layout for use with Applicants&#39; novel beverage cooling system which shows a tabletop supporting the unit, which tabletop in turn is supported by legs or a cart or the like; the product here, two different beverages, are provided in feed lines to the rear of the housing of the unit. 
           [0018]      FIG. 7  is a perspective view of the cold plate showing refrigeration lines and a pair of beer lines laying adjacent one another and embedded within an aluminum casting. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0019]    The standalone, self-contained beverage dispenser  10  of the present invention is shown in  FIG. 1 . Although the subject invention will be described in the context of the beverage to be dispensing being beer, it is to be understood the invention is not limited to the dispensing of beer. Beverage dispensing valves  10   a  and  10   b  stand out the front end of housing  14 . The beverage dispensing outlets may be beer taps or other such dispensers as those known in the art. A beverage spill tray  16  is positioned beneath the outlets  10   a  and  10   b . Beverage dispenser  1  may be mounted on a countertop, rolling cart or other support surface. The beverage dispenser I may be easily installed at a desired location. One needs simply to run the product lines from the beverage supply, for example, a beer keg, to the location for connection to the beverage dispensing unit. 
         [0020]    The refrigerant cooling system  20  of the subject invention is shown in  FIG. 2 . The cooling system  20  includes reservoir  22  which acts as the reservoir for the refrigerant, which is in fluid communication with cold plate  24  via refrigerant line  25 . Refrigerant cooling lines acting as an evaporator, extend through cold plate  24  to cool corresponding beverage lines which also extend through cold plate  24 . The cold plate utilized, including, for example,  40  pounds of cast aluminum, is a standard cold plate known to those skilled in the art wherein the beverage and refrigerant lines may be wound or located within the cold plate to increase the length of the lines positioned within said cold plate. The cooling system  20  also includes accumulator  26 , compressor  28  and refrigerant condenser  30 . As shown, refrigerant exits the cold plate  24  and flows to accumulator  26  via refrigerant line  27 . From the accumulator  26 , the refrigerant travels to the compressor  28  via refrigerant line  29 . The refrigerant flows from the compressor  28  to the condenser  30  via refrigerant line  31 . 
         [0021]    The operation of the refrigerant system is described below, in connection with  FIGS. 2 and 3 . 
         [0022]    The refrigerant, which in a preferred embodiment is type  404   a , enters the compressor  28  at point A as a low pressure gas and is discharged from the compressor as a high pressure gas at point B. It then enters the top of the condenser  30  at point C. 
         [0023]    The refrigerant is cooled in the condenser, exiting it as a high pressure liquid, and passes through a drier  32  (which retains unwanted scale, dirt and moisture) to the liquid line valve  34 , which is open whenever the cold plate  24  is warm enough to require cooling, as determined by a pressure switch Transducer TS  1  (pressure transducer or thermistor, for example). 
         [0024]    The refrigerant, still in a high pressure liquid state, flows through the liquid line valve  34  and enters the reservoir tank  22 , which serves as a storage or surge tank for the refrigerant at point D. 
         [0025]    At point E, the refrigerant exits the reservoir tank, passes through a sight glass  36  (where bubbles will be observed if the system is low on refrigerant) and encounters the thermal expansion valve TXV  38 . 
         [0026]    A pressure differential is provided across the thermal expansion valve. This valve includes a sensor bulb that measures the degree (or lack) of superheat of the suction gas exiting the cold plate and expands or contracts to allow the flow of refrigerant to be varied according to need. The refrigerant leaving the thermal expansion valve will be in a low pressure liquid or liquid/vapor state when it enters the cold plate. 
         [0027]    At the thermal expansion valve  38  there may also be a small equalizer tube  39  connected to the outlet cold plate  24 . The equalizer tube  38  helps to equalize the pressure between the inlet and outlet side of the cold plate  24 . 
         [0028]    After passing through the thermal expansion valve  38 , the refrigerant enters the cold plate  24  at point G. As the liquid or liquid/vapor refrigerant enters the cold plate it is subjected to a much lower pressure due to the suction created by the compressor and the pressure drop across the expansion valve. It will also be adjacent warmer beer lines. Thus, the refrigerant tends to expand and evaporate. In doing so, the liquid refrigerant absorbs energy (heat) from beverage lines within the cold plate  24 . 
         [0029]    The low pressure gas leaving the cold plate  24  encounters the evaporator valve  40 , whose function is to trap refrigerant in the cold plate during system shutdown cycle. From the evaporator valve  40 , the gas passes into accumulator  26 , which help prevent any slugs of liquid refrigerant from passing directly into the compressor, and continues back to the compressor  28 . The thermal expansion valve  38  mentioned above is used instead of a capillary tube in order to provide improved response to the cooling needs of the cold plate  24 . 
         [0030]    The microprocessor controlled electrical control system  50  is illustrated in  FIGS. 2 and 2A . Refrigeration on/off switch SW  1  provides power to the entire system by manually depressing the switch. Pressure transducer PT 1  monitors the refrigerant pressure in the compressor low side and cycles off the compressor and condenser fan (not shown) when the pressure drops to a predetermined level, 15 psi in a preferred embodiment, and cycles the compressor and fan back on when the temperature sensor or pressure transducer TS  1  reaches a second predetermined level, 75 psi in a preferred embodiment. TS  1  monitors refrigerant temperature (or pressure) just downstream of the beverage cold plate. When the pressure drops to a predetermined level, approximately 55 psi in a preferred embodiment, TS  1  through control system  50  cycles off the beverage evaporator coil or cold plate by shutting liquid line solenoid coil  34  and evaporator valve  40 . The microprocessor then reads the transducer PT 1  until drawdown to a lower pressure than 55 psi is reached, here for example, 10-35 psi, where the compressor is cycled off by the microprocessor/controller. The monitor then looks to TS  1 . With the compressor off, the cold plate starts to warm. When the refrigerant pressure at TS  1  rises to a second predetermined level, approximately 72-75 psi in a preferred embodiment, the TS  1  through microprocessor/control system  50  turns on the compressor and opens evaporator solenoid coil  40  and liquid line solenoid  34 . A push-button defrost switch  42  is provided to cycle on the hot gas solenoid and cycle off the condenser fan to deliver hot gas to the cold plate should the product in the cold plate become frozen. 
         [0031]    Sensor/transducer TS 1  responds to the cold plate  24  temperature by reading the pressure or temperature of the refrigerant as it is discharged from the cold plate. When the cold plate becomes warm enough, the liquid line valve  34  and the evaporator valve  40  open, thereby allowing refrigerant to flow throughout the system. When the cold plate becomes cool enough these valves  34 / 40  will close, trapping most refrigerant in the system but with the electronic control al lowing refrigerant to pump from the accumulator into the compressor down until PT 1  reads about 15 psi (typically between 10-35 psi). 
         [0032]    As shown in  FIG. 2 , defrost valve  42  is installed between the compressor discharge tube and the cold plate inlet. A manually operated momentary switch  44  may be deployed to trigger the defrost cycle. This signals the microprocessor to open the defrost valve  42  for a preset defrost cycle time, normally 30 seconds, and allows high pressure gas from the compressor to be pumped into the cold plate to thaw it, should it freeze up or get too cold. To prevent damaging the system, the switch should not be held longer than necessary. 
         [0033]    The TXV  38  control s and meters the amount of refrigerant that flows into the evaporator based on the temperature with a sensing bulb  41  that is typically located on the suction line where it leaves the evaporator coil. The temperature differential of the evaporator inlet and outlet typically determines the opening and closing of the TXV  38  valve seat to either add refrigerant or constrict refrigerant flow to the evaporator. Other devices known in the art may control pressure of refrigerant into the evaporator. 
         [0034]    An electronic microprocessor/controller  50  operates the compressor, condenser fan, and solenoids  34 / 40 . The microprocessor controller engages a power off switch, a defrost switch  42 , temperature sensor (from evaporator thermal sensor, a temperature sensor or pressure transducer) TS  1 , and an overheat temperature sensor  51  (from high side of condenser), as well as a pressure/transducer PT  1  just upstream of the low end of the compressor. 
         [0035]    Outputs (110 volt AC) include normally closed solenoids ( 2 )  34 / 40 , the compressor (typically about one-third horsepower) and the condenser fan (typically about 14 watt). Defrost solenoid  42  and a power on and defrost cycle LED include controller outputs. 
         [0036]    In the on/run mode (when the power switch is activated), the compressor, condenser fan, and solenoid pair  34 / 40  are activated. Compressor pumps refrigerant and the temperature of the cold plate will drop as the refrigerant goes through the cold plate. The “power on” LED is on. The monitor is looking at TS  1  looking for the solenoid valves shutoff condition, the intermediate set point here, for example, about 55 psi. 
         [0037]    “Stop” mode occurs when the intermediate set point evaporator temperature sensor TS  1  is reached, for example, approximately 29° F. (68.0 psi with Suva® 404A). The solenoids  34 / 40  are closed trapping liquid refrigerant in the cold plate and reservoir. The condenser fan and compressor continue to run until the pressure/vacuum transducer PT 1  set point is reached. This is about 15 psi. This action assures that there is little or no liquid refrigerant left in the accumulator. At this point, the fan and the compressor turn off and wait for a microprocessor signal from the evaporator temperature sensor TS  1 . “Power on” LED remains energized. 
         [0038]    When temperature of the evaporator at TS  1  increases to an upper limit, typically about 33° F. (74.0 psi with 404A or other suitable refrigerant), the “on” mode is automatically activated by the controller and cycles the compressor on and the solenoids open. 
         [0039]    This illustrates the controller in its normal operating mode. However, if the temperature of the high side thermal sensor  51  exceeds a set point (overheat), the system shuts down the compressor, fan, and solenoids and alternately flashes the LED indicators. This is a warning that the system has overheated. 
         [0040]    If the system freezes up or gets too cold, the momentary “defrost” switch is activated. The defrost solenoid is activated and the defrost LED flashes for a defrost cycle. The cycle is timed to last about 15-20 seconds, after which the LED turns off and the dispenser returns to the normal on/run cycle. 
         [0041]    One of the purposes of the electronic controller  50  is to maintain the compressor in an off position until the temperature of the evaporator reaches an upper limit, typically about 33° F., and the on mode is activated again. Thus, if there is any liquid refrigerant in the accumulator and it evaporates, as the system warms up or pressure increases, the pressure switch at the low end of the compressor will not cycle the compressor on. That is to say, the microprocessor controller  50  will provide for compressor run/on when solenoids  34 / 40  are de-energized and closed, but only until PT  1  reads about 15 psi or between about 10-35 psi, (thereby ensuring evaporation of any liquid refrigerant in accumulator  26 ). 
         [0042]      FIGS. 3 and 4  illustrate an equipment layout for the embodiment of Applicants&#39; device as set forth in  FIGS. 1 and 2 . It is seen with respect to  FIGS. 3 and 4 , that the cold plate  24  is set vertically with respect to a base  25  of the cooling system  20 . Furthermore, it can be seen that the condenser  30  is also set vertically and spaced apart from the cold plate  24 . A substantial number of the elements are set between the vertically oriented cold plate and condenser, including the compressor, drier, solenoids, sight glass, liquid line valve, thermal control valve, evaporator valve, reservoir tank, and accumulator. Moreover, the fan for the condenser is mounted inside the unit exhausting air through vents in the rear view of the unit (see  FIG. 4 ). 
         [0043]      FIGS. 5 and 7  illustrate an embodiment of an arrangement of refrigeration lines and beer lines that may be used in the cold plate. It is seen with respect to  FIG. 5  that refrigeration lines lay in a plane, as do the beverage lines. Adjacent to each beer line plane lays a refrigeration time plane for uniform heat transfer. 
         [0044]      FIG. 6  illustrates a manner in which Applicants&#39; novel cooling system  20  may be set up on a support surface or a table top TT, wherein the product (beverage) being supplied to the system, here from two kegs or other containers of liquid product, may enter the system from the rear. In an alternate preferred embodiment, the lines from the product to the cooling system may enter the system from beneath the table top TT and beneath the base  25 . Another suitable arrangement would be provided on a table top TT with a support member that is in the nature of a cart  31  having wheels (not shown), so that the unit may be wheeled around. 
         [0045]    Part of the advantages of the system described is the microprocessor controlled solenoid valves trapping refrigerant responsive to the microprocessor signals as set forth above. Normally on most systems when the system shuts down, the pressure differential will bleed back down to equilibrium, and in a normal situation when the system starts up, there is a time lag to drive up pressure in the condenser as the system starts back up. In the system set forth herein, however, by the action of the solenoid shutdown, pressure is maintained and bleed down is avoided. That is to say, there is a “stop action” freeze of the refrigeration cycle which allows an almost instantaneous return to the refrigeration cycle without the necessity of loading up the condenser. 
         [0046]    While the subject of this specification has been described in connection with one or more exemplary embodiments, it is not intended to limit the claims to the particular forms set forth. On the contrary, the appended claims are intended to cover such alternatives, modifications and equivalents as may be included within their spirit and scope.