Abstract:
A carbonated beverage is furnished from a source at a first pressure to a reservoir in which a quantity of the beverage is held a second pressure level that is less than the first pressure and greater than atmospheric pressure. When it is desired to dispense the carbonated beverage into a serving container, the reservoir is vented to the atmosphere so that the beverage is dispensed at substantially atmospheric pressure. The amount of carbonated beverage in the reservoir is sensed and when that amount drops below a first level, carbonated beverage is added from the source while the reservoir is vented to the atmosphere. The venting terminates when the amount of beverage in the reservoir reaches a second level. The beverage continues to flow into the reservoir thereafter for a predefined period of time causing the pressure to increase to the second pressure level.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to equipment for dispensing a carbonated beverage into an open container from which the beverage will be consumed; and more particularly to such equipment in which the dispensing occurs in a manner that minimizes foaming of the beverage. 
     2. Description of the Related Art 
     It is common for carbonated beverages, such as soda and beer, to be supplied in a sealed canister or keg that then is connected to a tap at an establishment, at which the beverage is to be served. As used herein the term “establishment” includes businesses, residences and other facilities at which a carbonated beverage is served. Pressurized gas, such as carbon dioxide, is injected into the keg to force the liquid beverage through an outlet tube to the tap from which it is dispensed into serving containers of various sizes. 
     The carbonated beverage usually foams upon entering the serving container. As a consequence, personnel operating the tap typically fill the serving container until the level of foam reaches the brim and then wait for the foam to settle before adding additional beverage. In some instances several iterations of this process are required before the container is filled with liquid to the proper serving level. Such “topping off” necessitated by the foaming of the beverage prolongs the dispensing operation and impedes the ability to fully automate carbonated beverage dispensing. 
     Automated dispensing is particularly useful in establishments where large volumes of beverages are served, such as sports arenas and stadiums. It is desirable at such facilities to fill each container to the full serving level as fast as possible with minimal waste. 
     U.S. Pat. No. 5,603,363 describes a dispensing system which satisfies that desire. In that system, the carbonated beverage is fed into an elevated tank which is open to the atmosphere so that the beverage stored therein is at atmospheric pressure at all times. A spout is located beneath the tank and has a valve through which the beverage flows into a serving container. Selective operation of the valve and movement of the serving container enable rapid dispensing with minimal foaming. As a result of the tank being open to the atmosphere, the beverage tends to degas upon prolonged storage in the tank. In addition, there is a concern that bacteria and other substances may enter the open tank and contaminate the beverage therein, especially between hours of operation of the beverage establishment. 
     Alternative systems, such as described in U.S. Pat. No. 3,881,636, employ a closed tank with a vent tube at the top of the tank that provides a restricted passage to the atmosphere. The beverage is fed to the tank under the same pressure as in the keg and is maintained substantially at that elevated pressure until a spout is opened to fill a glass. At that time the tank pressure is reduced to the atmospheric level before the valve on the spout is opened. In a high volume dispensing establishment, this latter type of dispensing system has the disadvantage that time is lost while the reservoir is brought down to atmospheric pressure before the spout is opened. A further delay results from having to raise the tank to the keg pressure in order replenish the beverage in the tank. Thus it is desirable to increase the speed of dispensing further. In addition, this latter system has a small orifice through which the tank always is open to the atmosphere. Thus contaminants may enter this tank during prolonged periods of non-use. 
     SUMMARY OF THE INVENTION 
     To dispense a carbonated beverage into a serving container, a reservoir of a dispenser is connected to a source which supplies the carbonated beverage at a first pressure level that is greater than atmospheric pressure. A quantity of the carbonated beverage is held in the reservoir at a second pressure level that is less than the first pressure level and substantially greater than atmospheric pressure. This intermediate second pressure level inhibits gas from escaping from the beverage so that the carbonation is maintained. 
     When it is desired to dispense the carbonated beverage into the serving container, a vent passage between the reservoir and an ambient environment is opened to lower pressure in the reservoir to substantially atmospheric pressure. After the reservoir is at substantially atmospheric pressure, another passage in opened through which the beverage flows from the reservoir into the serving container. Foaming that often occurs as a carbonated beverage flows into a serving container is minimized by reducing the reservoir pressure to substantially atmospheric pressure. 
     In the preferred embodiment of the dispensing method, the amount of carbonated beverage contained in the reservoir is sensed. When less than a first amount of carbonated beverage is in the reservoir, carbonated beverage is transferred from the source into the reservoir. Thereafter, when carbonated beverage in the reservoir reaches a second amount, the vent passage is closed. The transfer of the carbonated beverage is terminated a predefined period of time after closing the vent passage, wherein the quantity of the beverage that enters the reservoir during that predefined period of time causes the pressure to increase to the second pressure level. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram of a beverage dispensing system according to the present invention; and 
     FIG. 2 is a graph of the pressure in a reservoir while beverage is being dispensed into a container. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With initial reference to FIG. 1, a beverage dispensing system  10  receives a fully mixed carbonated beverage, such as beer or soda from a keg  12 . A source of pressurized gas, for example a cylinder  14  of carbon dioxide, is connected by a pressure regulator  16  to an inlet of the keg  12 . The pressure regulator  16  maintains the internal pressure of the keg at a first level recommended by the beverage supplier. A pressure of 15 psig (1.0 bar) is commonly used for many beers. It should be understood that this pressure may deviate ±2 psi (0.14 bar) and still be considered substantially at the recommended pressure level. Alternatively, a compressor can apply pressurized air to the keg, or a pump system can be used to transport the beverage from the keg  12  to the beverage dispensing system  10  at the recommended pressure. The keg pressure is commonly referred to as the “rack” pressure, and may be applied to several kegs within the establishment at which the beverages are being served. 
     The application of pressure to the keg  12  forces the beverage from an outlet through a dispensing line  18 . The beverage line  18  is connected to an internal coil of a conventional chiller  20  which lowers the temperature of the beverage to a desired dispensing temperature. Although many establishments store the keg  12  in a walk-in refrigeration unit, that may not be the case for a high volume establishment. Also when a keg is exhausted, a replacement may be obtained from an unrefrigerated area. After being chilled, the beverage flows through line  22  to an inlet valve  24  of a beverage reservoir  26  at the location at which the beverage will be dispensed into serving containers. The inlet valve  24  is operated by an actuator  25  in response to an electric signal. 
     The reservoir  26  has a closed inner chamber  28  into which the beverage flows when the inlet valve  24  is opened. An outer wall of the reservoir  26  forms an outer cavity  30  extending around the inner chamber  28 . Chilled glycol is circulated through this outer cavity  30  to maintain the contents of the inner chamber  28  at the proper temperature (e.g. approximately 35° F.). Specifically, a pump  32  draws glycol from the outer cavity  30  via an outlet line  34  and forces the glycol through another coil within the chiller  20 . This cools the glycol to the desired temperature and the chilled glycol is returned through an inlet line  36  to the outer cavity  30  of the reservoir  26 . Baffles may be provided within the outer cavity  30  to ensure that the chilled glycol flows completely around the inner chamber  28  to maintain the beverage  38  therein at a relatively uniform temperature. 
     The beverage  38  partially fills the inner chamber  28  to a height that is detected by a level sensor  40 . The upper portion  42  of the closed inner chamber  28  is filled with a mixture of air and carbon dioxide which outgasses from the beverage. A breather tube  44  extends between the inner chamber  28  and the ambient atmosphere and has a pressure control valve  46  that is operated by an actuator  48 . As will be described, the pressure control valve  46  is opened to vent the gas in the inner chamber  28  into the ambient environment. A filter  45  may be provided to trap any contaminate from entering through the breather tube  44 . 
     The valves  24  and  46  are electrically operated by signals from a controller  50  in response to the signal from the level sensor  40 . The controller  50  has a conventional hardware design that is based on a microcomputer and a memory in which the programs and data for execution by the microcomputer are stored. The microcomputer is connected input and output circuits that interface the controller to switches, sensors and valves of the beverage dispenser  10 . The software executed by the controller responds to those input signals by operating the valves  24  and  46  as will be described. 
     With continuing reference to FIG. 1, the reservoir  26  includes a dispensing spout  52  extending downwardly there from. The flow of beverage through the spout  52  is controlled by a movable dispensing valve element  53  that is mounted at the lower end of a tube which extends vertically through the spout  52  and the reservoir  26 . An upper end of the tube  54  passes through a seal  55  and is connected to an actuator  56 , which raises and lowers the tube. That motion brings the dispensing valve element  53  into and out of engagement with the spout to allow beverage to flow into a serving container  70  placed there beneath. The actuator  56  is operated by signals from the controller  50 , as will be described. 
     A switch  58  is mounted on the valve element  53  and is depressed by the bottom of a serving container  70  placed under the spout  52  and raised upward. The switch  58  is connected by wires which run through the tube  54 , emerge from the actuator  56  and extending to an input of the controller  50 . 
     The beverage is supplied to the reservoir  26  from the keg at a first pressure level P 1  that corresponds to the rack pressure of the keg  12  (e.g. 15 psig). While the beverage  38  is being held in the reservoir  26  the pressure control valve  46  is closed so that the reservoir is sealed from the atmosphere surrounding the dispenser. This maintains the pressure within inner chamber  28  at a second pressure level P 2  that is referred to as the “holding pressure.” The second pressure level is substantially greater than atmospheric pressure, that is at least one psi and preferably at least five psi above atmospheric pressure for beer. Because the holding pressure is substantially above atmospheric pressure and because the beverage in the reservoir is held at a relatively low temperature (e.g. approximately 35° F.), outgassing of the beverage is minimized during the relatively brief period of time that the beverage remains in the reservoir. 
     When a server desires to dispense the beverage, an open serving container  70  is placed beneath the spout  52  and moved upward until the bottom of the container presses the switch  58  on the valve element  53 . This transmits a signal to the controller  50  indicating that a beverage dispensing operation should commence. 
     If the beverage is dispensed through the spout  52  at the holding pressure P 2 , turbulence may occur producing excessive foam in the beverage container which is an undesirable effect. It has been discovered that minimal foaming occurs in the serving container  70  when the pressure in the inner chamber  28  substantially equals that of the container. A slight pressure difference, ±1 psi for example, can exist without producing an excessive amount of foam which would deprive the customer of a full serving of the beverage. As a consequence with reference to FIG. 2, when the controller  50  initiates a pour cycle at time T 1 , the pressure control valve  46  in FIG. 1 is opened to vent the pressure within the inner chamber  28  through the breather tube  44  to the outside atmosphere. This decreases the pressure within inner chamber  28  from the holding pressure P 2  to a lower dispensing pressure P 3  which is substantially equal to atmospheric pressure. 
     After the pressure control valve  46  has been open for a sufficient period of time, interval T 1  to T 2 , so that the inner chamber pressure has reached atmospheric pressure P 3 , the controller  50  energizes the actuator  56  at time T 2 , which causes the dispensing valve element  53  to move away from the end of the spout  52 . This opens a passage for fluid to flow from the spout  52  into the serving container  70  held there beneath. The contour of pour provided by this movement of the valve member  53  is defined by characteristics of the beverage, the temperature of the beverage, and the pressure at which the pour is occurring. The shape of the contour can be varied by controlling the displacement of the valve element  53  with respect to the end of the spout  52  and thereby create a desired amount of foam during the dispensing operation. 
     In the preferred version of the dispensing system  10  the pressure control valve  46  remains open as the dispensing valve element  53  opens so that the inner chamber continues to be vented to the atmosphere. However, as the spout valve element cracks open, the beverage may tend to flow through the initial small opening at a relatively high velocity which produces turbulence and thus foam in the serving container  70 . This adverse effect can be prevented by optionally creating a negative pressure in the spout  52  which restricts the beverage flow until the valve has opened to a point at which foaming is unlikely to occur. To accomplish this variation, the controller  50  closes the pressure control valve  46  at time T 2  when the dispensing valve element  53  opens. This action seals the upper portion  42  of the inner chamber  28  from the external atmosphere. Therefore, as the spout  52  opens, a slight vacuum is created due to the weight of the beverage in the reservoir. This limits the initial flow of beverage from the spout  52  to a relatively small quantity, which is particularly important for extremely carbonated beverages that foam easily. However, the duration of the negative pressure (indicted by dashed line  72 ) is relatively short as the pressure control valve opens again at T 3 . Thus the pressure within inner chamber  28  returns to the atmospheric level at time T 4  at which pressure level the inner chamber remains during the rest of the beverage dispensing time. 
     At some point during the dispensing operation, designated time T 5 , the level of the beverage in the inner chamber  28  decreases to a point that the level sensor  40  sends a signal to the controller  50 . The controller  50  responds by activating the actuator  25  for the beverage inlet valve  24  to add beverage from the keg  12  into the reservoir  26 . Although the beverage entering the inner chamber  28  is at the relatively high rack pressure of the keg (e.g. 15 psig), the inner chamber still is vented to the atmosphere through the passage provided by the open breather tube  44 . As a consequence, the pressure within the inner chamber remains substantially at the atmospheric pressure level. Because the additional beverage is introduced below the level of beverage in the reservoir, this pressure differential does not produce foaming. 
     The beverage continues to flow from the spout  52  between times T 2  and T 6  while pressure in the reservoir is maintained at the atmospheric dispensing level P 3 . The controller is programmed to hold the dispensing valve element  53  in the open position for a predefined interval corresponding to the amount of time required to fill the serving container  70 . In high volume dispensing operations, such as at a sports venue, beer typically is sold is only one size of container. Therefore the dispenser&#39;s controller  50  can be programmed with the corresponding dispensing period required to fill such serving containers. If serving containers of different sizes are being used, a control panel with pushbutton switches for each different container size can be provided to enable the operator to signal the controller  50  as to the size of the particular container to be filled. 
     When the dispensing period elapses at time T 6 , the controller  50  de-energizes the spout actuator  56 , thereby closing the valve element  53 . However the beverage continues to flow into the inner chamber  28  from the keg  12  and the breather tube  44  remains open to vent air displaced by the entering beverage. 
     At time T 7  the level indicator  40  signals the controller  50  that the reservoir  26  contained the desired amount of carbonated beverage. In response to that signal, the controller  50  operates the valve element  46  to close the breather tube  44  and seal the inner chamber  28  from the surrounding atmosphere. The inlet valve  24  remains open for a fixed period of time (T 7  to T 8 ) to add enough additional beverage into the inner chamber  28  so that the internal pressure increases to the holding pressure level P 2 , as depicted graphically in FIG.  2 . It has been determined that there is a correlation between the amount of time that the beverage continues to flow after closing the breather tube  44  and the internal pressure level. The length of the interval that the inlet valve  24  remains open is determined empirically for a given rack pressure in the keg  12 . When the controller determines that this time period has elapsed, the inlet valve  24  is closed at time T 8 . It should be understood that the relative position of the points in time in FIG. 2 are exemplary and the specific relationships will vary depending on the characteristics of a given dispensing system. 
     When the beverage establishment closes, such as at the end of the business day, the reservoir  26  is brought up to the rack pressure P 1  as denoted by the dashed line  74  in FIG.  2 . This will maintain the beverage  38  stored in the reservoir at a pressure where minimal degassing occurs. The inner chamber pressure is lowered again to the holding pressure P 2  when the establishment reopens or at the commencement of the next dispensing operation. In instances where a relatively long time period (e.g. ten minutes) elapses after a previous dispensing operation, the reservoir pressure can be increased to the rack pressure P 1  to further limit the degassing. 
     The present beverage dispensing system  10  employs a closed reservoir  26  that prevents contaminants from entering which would adversely effect the beverage being stored in the dispenser. At the same time, the pressure of the beverage is regulated so that it is stored at a sufficiently high pressure to prevent gas from escaping from the beverage, and at a relatively low pressure so that the pressure can be rapidly decreased to the atmospheric level for pouring into a serving container with minimal foaming. The present system does not require pressure sensors to properly control the pressure level in the storage reservoir  26 . 
     The foregoing description was primarily directed to a preferred embodiment of the invention. Although some attention was given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that arc now apparent from disclosure of embodiments of the invention. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.