Abstract:
A food dispensing machine includes a product chamber and an ingredients source including a gas source connected to the product chamber. A flow control device is configured to control ingredients flow from the ingredients source to the product chamber. A pressure measurement device is configured to output a gas pressure signal, and a controller is configured to receive the gas pressure signal and determine a gas flow control signal based on the gas pressure signal. The controller outputs the gas flow control signal to the flow control device.

Description:
BACKGROUND 
       [0001]    This disclosure relates generally to food dispensing machines, and more particularly to frozen carbonated beverage machines. 
         [0002]    Food dispensing machines, such as frozen carbonated beverage machines produce a frozen beverage by freezing a mixture of water, syrup concentrate and carbon dioxide in a mixing, or freezing, chamber. The freezing chamber is typically surrounded by a coil that contains refrigerant to cause freezing of the mixture inside to a desired level of consistency. The mixture is removed from the inner surface and mixed by a rotating shaft driving a scraping/mixing member attached to the shaft. The frozen mixture consistency is controlled by any of a number of methods that turns on the refrigeration to freeze and turns off the refrigeration when the mixture reaches the desired consistency. A consumer can then dispense the product as desired through a dispensing valve. 
         [0003]    The water and syrup concentrate are usually supplied to the freezing chamber via flow controls to maintain a precise flow rate of liquid even as the inlet and/or discharge pressures vary. The carbon dioxide gas flow rate is controlled via a regulator and orifice. The volume of the product dispensed from the mixing chamber is defined as “overrun.” A beverage that doubles its volume when it is dispensed from the mixing chamber in a semi-frozen state is defined as having an overrun of 100%. Generally, the more carbon dioxide that is added to the mixing chamber, the higher the overrun. It is desirable to be able to control overrun so that the consistency of the product can be maintained. 
         [0004]    The regulator controls the pressure of gas input to the freezing chamber, but the discharge pressure from the regulator can vary and result in fluctuations in the gas flow rate. One method to mitigate this fluctuation is to increase the inlet pressure to the regulator until the normal discharge pressure range from the regulator is low enough as not to affect the flow rate. However, pressure regulators can drift, resulting in variations in the discharge pressure. Further, the carbon dioxide content of the finished product often needs to be adjusted to produce the desired drink consistency. 
       SUMMARY 
       [0005]    A food dispensing machine and method are disclosed. The machine includes a product chamber and an ingredients source including a gas source connected to the product chamber. A flow control device is configured to control ingredients flow from the ingredients source to the product chamber. A pressure measurement device is configured to output a gas pressure signal, and a controller is configured to receive the gas pressure signal and determine a gas flow control signal based on the gas pressure signal. The controller outputs the gas flow control signal to the flow control device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain principles of embodiments. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts. 
           [0007]      FIG. 1  is a block diagram illustrating aspects of a food dispensing machine in accordance with aspects of the present disclosure. 
           [0008]      FIG. 2  is a block diagram illustrating a gas flow control system suitable for the machine shown in  FIG. 1 . 
           [0009]      FIG. 3  is a block diagram illustrating further aspects of the gas flow control system shown in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0010]    In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims. 
         [0011]    It is to be understood that the features of the various exemplary embodiments described herein may be combined with each other, unless specifically noted otherwise. 
         [0012]      FIG. 1  is a block diagram illustrating a food dispensing machine machine system  10  in accordance with the present disclosure. The system  10  includes an ingredient supply  12 , a flow control  14 , a control circuit or controller  16 , and a product chamber  18 . In some embodiments, the machine  10  is a frozen carbonated beverage dispensing machine. For producing frozen carbonated beverages, the ingredient supply  12  includes water, syrup and carbon dioxide. The product chamber  18  is a freezing chamber, and typical systems may include two or more freezing chambers  18  and associated syrup supplies allowing a single system to provide multiple beverage flavors. 
         [0013]    Water and syrup are flow from their respective sources to the freezing chamber  18  via the flow control  14 . The flow control  14  includes, for example, a brix adjuster that controls the amount of syrup that is mixed with the water and a solenoid controls the flow of the syrup/water mixture. The flow controllers for the water and syrup typically are set manually. 
         [0014]    In embodiments where the machine  10  produces frozen beverages, the freezing chamber  18  is cooled by a refrigeration system that may be controlled by the controller  16 . The controller  16  can be implemented by an appropriately programmed computer device as would be apparent to one skilled in the art having the benefit of this disclosure. The chamber  18  is surrounded by a coil that contains refrigerant to cause freezing of the mixture inside to a desired level of consistency. The mixture is removed from the inner surface and mixed by a rotating shaft driving a scraping/mixing member attached to the shaft. The frozen mixture consistency is controlled by any of a number of methods that turns on the refrigeration to freeze and turns off the refrigeration when the mixture reaches the desired consistency. The product is then dispensed from the freezing chamber  18  by a dispensing valve 
         [0015]      FIG. 2  illustrates further aspects of the system  10 . Referring now to  FIG. 2 , carbon dioxide gas (CO 2 ) is supplied from a CO 2  supply such as a tank  20  to a pressure regulator  22  configured to adjust the pressure of the carbon dioxide provided to the mixing chamber  18 . In other implementations, a gas other than CO 2  is provided. For example, air can be injected into the beverage to produce a frozen uncarbonated beverage. 
         [0016]    The pressure of the carbon dioxide flowing into the regulator  22  from the tank  20  is approximately 70 psi in some embodiments, with the pressure of the carbon dioxide exiting the regulator  22  and being supplied to the mixing chamber  18  being about 60 psi. 
         [0017]    The pressure of the regulated CO 2  gas is measured by a pressure measurement device  24  such as a pressure transducer. In one implementation, a model 90CP2-1 0231 (0-100 PSIG) from Sensata Technologies, Inc. is used. The pressure measurement is provided as an input to the controller  16 , which provides a control signal to a flow control device such as a solenoid  26  to control the flow of the CO 2  gas to the freezing chamber  18  based on the determined gas pressure. A suitable solenoid is provided in one implementation by Kendrion Tri-Tech LLC of Mishawaka, 1N, Part No. 19390001C. Other embodiments are envisioned in which other aspects of the gas are monitored and used as an input to the controller. For example, the measured pressure could be compared to a target pressure and the pressure error could be received by the controller  18  to determine a control signal. 
         [0018]    In some embodiments, the gas flow rate is controlled by varying a pulse-width modulation (PWM) signal controlling the solenoid  26 . With PWM control of the solenoid  26  the average on time of the solenoid  26 , and thus the gas flow rate, is controlled by turning the solenoid on and off (opening and closing) at a fast pace. The longer the solenoid  26  is on compared to the off periods, the longer its average on time. The term duty cycle describes the proportion of “on” time to the regular interval or “period” of time. A lower duty cycle corresponds to shorter on time of the solenoid  26  because the solenoid is off for most of the time period. Duty cycle is expressed in percent, with 100% being fully on. 
         [0019]      FIG. 3  illustrates an example of a gas flow control process and system. The controller  18  receives a gas pressure measurement signal  100 . In the embodiment illustrated in  FIG. 2 , the pressure signal  100  is provided by the pressure transducer  22  such that the controller  18  receives an indication of the regulated CO 2  pressure. The controller  18  includes a function  110  that calculates a duty cycle  112  based on the pressure measurement signal  100 . The calculated duty cycle  112  is provided to a solenoid driver  114  that converts the duty cycle  112  to a control signal that is output to the solenoid  26 . Thus, the flow rate of CO 2  to the product chamber is dynamic—it can be recalculated and if necessary, changed based on changes in gas pressure. In one embodiment, this is implemented via an empirically derived look up table stored in a memory associated with the controller  18 . Table 1 below is an example of a portion of such a look up table, illustrating the duty cycle corresponding with pressures ranging from 60 psi to 75 psi. Of course, the entire look up table would likely have a larger range of gas pressures and corresponding duty cycles. 
         [0000]    
       
         
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
             
               
                   
                 C02 PSI = 60 
                 Duty Cycle = 81 
               
               
                   
                 C02 PSI = 65 
                 Duty Cycle = 76 
               
               
                   
                 C02 PSI = 70 
                 Duty Cycle = 72 
               
               
                   
                 C02 PSI = 75 
                 Duty Cycle = 68 
               
               
                   
                   
               
             
          
         
       
     
         [0020]    In the implementation illustrated in  FIG. 3 , the controller  18  also receives a target flow rate signal  102 , which is also used as an input by the function  110  to calculate the duty cycle  112 . The desired flow rate  102  could simply represent a desired CO 2  flow rate, or it could be expressed in terms of a desired overrun, for example, when implemented in conjunction with a frozen beverage machine. A higher gas flow results in a higher the overrun, so that the beverage produced will be the lighter. The lower the gas flow rate is, the lower the overrun will be, and thus the heavier and more “liquidy” the beverage product will be. With an implementation such as this, the look up table additionally includes a desired flow input. Table 2 below is an example of a portion of such a look up table, adding desired flow (“flow”) to the data included in Table 1 above. 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
             
             
               
                   
                 C02 PSI = 60 
                 Flow = 20 
                 Duty Cycle = 33 
               
               
                   
                 C02 PSI = 60 
                 Flow = 22 
                 Duty Cycle = 36 
               
               
                   
                 C02 PSI = 60 
                 Flow = 24 
                 Duty Cycle = 40 
               
               
                   
                 C02 PSI = 60 
                 Flow = 26 
                 Duty Cycle = 43 
               
               
                   
                 C02 PSI = 60 
                 Flow = 28 
                 Duty Cycle = 46 
               
               
                   
                 C02 PSI = 60 
                 Flow = 30 
                 Duty Cycle = 50 
               
               
                   
                 C02 PSI = 60 
                 Flow = 32 
                 Duty Cycle = 52 
               
               
                   
                 C02 PSI = 60 
                 Flow = 34 
                 Duty Cycle = 55 
               
               
                   
                 C02 PSI = 60 
                 Flow = 36 
                 Duty Cycle = 58 
               
               
                   
                 C02 PSI = 60 
                 Flow = 38 
                 Duty Cycle = 62 
               
               
                   
                 C02 PSI = 60 
                 Flow = 40 
                 Duty Cycle = 65 
               
               
                   
                 C02 PSI = 60 
                 Flow = 42 
                 Duty Cycle = 68 
               
               
                   
                 C02 PSI = 60 
                 Flow = 44 
                 Duty Cycle = 71 
               
               
                   
                 C02 PSI = 60 
                 Flow = 46 
                 Duty Cycle = 75 
               
               
                   
                 C02 PSI = 60 
                 Flow = 48 
                 Duty Cycle = 78 
               
               
                   
                 C02 PSI = 60 
                 Flow = 50 
                 Duty Cycle = 81 
               
               
                   
                 C02 PSI = 60 
                 Flow = 52 
                 Duty Cycle = 85 
               
               
                   
                 C02 PSI = 60 
                 Flow = 54 
                 Duty Cycle = 88 
               
               
                   
                 C02 PSI = 60 
                 Flow = 56 
                 Duty Cycle = 91 
               
               
                   
                 C02 PSI = 60 
                 Flow = 58 
                 Duty Cycle = 94 
               
               
                   
                 C02 PSI = 60 
                 Flow = 60 
                 Duty Cycle = 98 
               
               
                   
                 C02 PSI = 60 
                 Flow = 62 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 60 
                 Flow = 64 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 60 
                 Flow = 66 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 60 
                 Flow = 68 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 60 
                 Flow = 70 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 60 
                 Flow = 72 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 60 
                 Flow = 74 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 65 
                 Flow = 20 
                 Duty Cycle = 31 
               
               
                   
                 C02 PSI = 65 
                 Flow = 22 
                 Duty Cycle = 34 
               
               
                   
                 C02 PSI = 65 
                 Flow = 24 
                 Duty Cycle = 37 
               
               
                   
                 C02 PSI = 65 
                 Flow = 26 
                 Duty Cycle = 40 
               
               
                   
                 C02 PSI = 65 
                 Flow = 28 
                 Duty Cycle = 43 
               
               
                   
                 C02 PSI = 65 
                 Flow = 30 
                 Duty Cycle = 46 
               
               
                   
                 C02 PSI = 65 
                 Flow = 32 
                 Duty Cycle = 50 
               
               
                   
                 C02 PSI = 65 
                 Flow = 34 
                 Duty Cycle = 52 
               
               
                   
                 C02 PSI = 65 
                 Flow = 36 
                 Duty Cycle = 55 
               
               
                   
                 C02 PSI = 65 
                 Flow = 38 
                 Duty Cycle = 58 
               
               
                   
                 C02 PSI = 65 
                 Flow = 40 
                 Duty Cycle = 61 
               
               
                   
                 C02 PSI = 65 
                 Flow = 42 
                 Duty Cycle = 64 
               
               
                   
                 C02 PSI = 65 
                 Flow = 44 
                 Duty Cycle = 67 
               
               
                   
                 C02 PSI = 65 
                 Flow = 46 
                 Duty Cycle = 70 
               
               
                   
                 C02 PSI = 65 
                 Flow = 48 
                 Duty Cycle = 73 
               
               
                   
                 C02 PSI = 65 
                 Flow = 50 
                 Duty Cycle = 76 
               
               
                   
                 C02 PSI = 65 
                 Flow = 52 
                 Duty Cycle = 79 
               
               
                   
                 C02 PSI = 65 
                 Flow = 54 
                 Duty Cycle = 82 
               
               
                   
                 C02 PSI = 65 
                 Flow = 56 
                 Duty Cycle = 85 
               
               
                   
                 C02 PSI = 65 
                 Flow = 58 
                 Duty Cycle = 88 
               
               
                   
                 C02 PSI = 65 
                 Flow = 60 
                 Duty Cycle = 91 
               
               
                   
                 C02 PSI = 65 
                 Flow = 62 
                 Duty Cycle = 95 
               
               
                   
                 C02 PSI = 65 
                 Flow = 64 
                 Duty Cycle = 98 
               
               
                   
                 C02 PSI = 65 
                 Flow = 66 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 65 
                 Flow = 68 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 65 
                 Flow = 70 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 65 
                 Flow = 72 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 65 
                 Flow = 74 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 70 
                 Flow = 20 
                 Duty Cycle = 29 
               
               
                   
                 C02 PSI = 70 
                 Flow = 22 
                 Duty Cycle = 32 
               
               
                   
                 C02 PSI = 70 
                 Flow = 24 
                 Duty Cycle = 35 
               
               
                   
                 C02 PSI = 70 
                 Flow = 26 
                 Duty Cycle = 38 
               
               
                   
                 C02 PSI = 70 
                 Flow = 28 
                 Duty Cycle = 41 
               
               
                   
                 C02 PSI = 70 
                 Flow = 30 
                 Duty Cycle = 44 
               
               
                   
                 C02 PSI = 70 
                 Flow = 32 
                 Duty Cycle = 47 
               
               
                   
                 C02 PSI = 70 
                 Flow = 34 
                 Duty Cycle = 50 
               
               
                   
                 C02 PSI = 70 
                 Flow = 36 
                 Duty Cycle = 51 
               
               
                   
                 C02 PSI = 70 
                 Flow = 38 
                 Duty Cycle = 54 
               
               
                   
                 C02 PSI = 70 
                 Flow = 40 
                 Duty Cycle = 57 
               
               
                   
                 C02 PSI = 70 
                 Flow = 42 
                 Duty Cycle = 60 
               
               
                   
                 C02 PSI = 70 
                 Flow = 44 
                 Duty Cycle = 63 
               
               
                   
                 C02 PSI = 70 
                 Flow = 46 
                 Duty Cycle = 66 
               
               
                   
                 C02 PSI = 70 
                 Flow = 48 
                 Duty Cycle = 69 
               
               
                   
                 C02 PSI = 70 
                 Flow = 50 
                 Duty Cycle = 72 
               
               
                   
                 C02 PSI = 70 
                 Flow = 52 
                 Duty Cycle = 75 
               
               
                   
                 C02 PSI = 70 
                 Flow = 54 
                 Duty Cycle = 77 
               
               
                   
                 C02 PSI = 70 
                 Flow = 56 
                 Duty Cycle = 80 
               
               
                   
                 C02 PSI = 70 
                 Flow = 58 
                 Duty Cycle = 83 
               
               
                   
                 C02 PSI = 70 
                 Flow = 60 
                 Duty Cycle = 86 
               
               
                   
                 C02 PSI = 70 
                 Flow = 62 
                 Duty Cycle = 89 
               
               
                   
                 C02 PSI = 70 
                 Flow = 64 
                 Duty Cycle = 92 
               
               
                   
                 C02 PSI = 70 
                 Flow = 66 
                 Duty Cycle = 95 
               
               
                   
                 C02 PSI = 70 
                 Flow = 68 
                 Duty Cycle = 98 
               
               
                   
                 C02 PSI = 70 
                 Flow = 70 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 70 
                 Flow = 72 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 70 
                 Flow = 74 
                 Duty Cycle = 100 
               
               
                   
                 C02 PSI = 75 
                 Flow = 20 
                 Duty Cycle = 28 
               
               
                   
                 C02 PSI = 75 
                 Flow = 22 
                 Duty Cycle = 30 
               
               
                   
                 C02 PSI = 75 
                 Flow = 24 
                 Duty Cycle = 33 
               
               
                   
                 C02 PSI = 75 
                 Flow = 26 
                 Duty Cycle = 36 
               
               
                   
                 C02 PSI = 75 
                 Flow = 28 
                 Duty Cycle = 39 
               
               
                   
                 C02 PSI = 75 
                 Flow = 30 
                 Duty Cycle = 41 
               
               
                   
                 C02 PSI = 75 
                 Flow = 32 
                 Duty Cycle = 44 
               
               
                   
                 C02 PSI = 75 
                 Flow = 34 
                 Duty Cycle = 47 
               
               
                   
                 C02 PSI = 75 
                 Flow = 36 
                 Duty Cycle = 50 
               
               
                   
                 C02 PSI = 75 
                 Flow = 38 
                 Duty Cycle = 51 
               
               
                   
                 C02 PSI = 75 
                 Flow = 40 
                 Duty Cycle = 54 
               
               
                   
                 C02 PSI = 75 
                 Flow = 42 
                 Duty Cycle = 57 
               
               
                   
                 C02 PSI = 75 
                 Flow = 44 
                 Duty Cycle = 59 
               
               
                   
                 C02 PSI = 75 
                 Flow = 46 
                 Duty Cycle = 62 
               
               
                   
                 C02 PSI = 75 
                 Flow = 48 
                 Duty Cycle = 65 
               
               
                   
                 C02 PSI = 75 
                 Flow = 50 
                 Duty Cycle = 68 
               
               
                   
                 C02 PSI = 75 
                 Flow = 52 
                 Duty Cycle = 70 
               
               
                   
                 C02 PSI = 75 
                 Flow = 54 
                 Duty Cycle = 73 
               
               
                   
                 C02 PSI = 75 
                 Flow = 56 
                 Duty Cycle = 76 
               
               
                   
                 C02 PSI = 75 
                 Flow = 58 
                 Duty Cycle = 79 
               
               
                   
                 C02 PSI = 75 
                 Flow = 60 
                 Duty Cycle = 81 
               
               
                   
                 C02 PSI = 75 
                 Flow = 62 
                 Duty Cycle = 84 
               
               
                   
                 C02 PSI = 75 
                 Flow = 64 
                 Duty Cycle = 87 
               
               
                   
                 C02 PSI = 75 
                 Flow = 66 
                 Duty Cycle = 89 
               
               
                   
                 C02 PSI = 75 
                 Flow = 68 
                 Duty Cycle = 92 
               
               
                   
                 C02 PSI = 75 
                 Flow = 70 
                 Duty Cycle = 95 
               
               
                   
                 C02 PSI = 75 
                 Flow = 72 
                 Duty Cycle = 98 
               
               
                   
                 C02 PSI = 75 
                 Flow = 74 
                 Duty Cycle = 100 
               
               
                   
                   
               
             
          
         
       
     
         [0021]    Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this invention be limited only by the claims and the equivalents thereof.