Abstract:
A beverage dispenser has gauges to measure the temperature of the beverage, in at least one embodiment beer, stored in a closed beverage container. The beverage is pressurized and a pressure gauge in the gas supply conduit line measures the pressure of the gas in the beverage container. A pressure regulator in the gas supply conduit line assists in ensuring that the pressure is consistent. The valve is closed during dispensation and the temperature and the gas pressure are measured immediately afterwards. By calculating the temperature change of the beverage and the pressure drop in the container, the amount of beverage can be calculated accurately. This in turn can be utilized to reliably calculate how beverage is left in the container and this information is then presented on a display, in at least one embodiment, as a series of indicator bars.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a beverage dispensing apparatus, particularly to an apparatus for dispensing beverage such as beer under predetermined pressure. 
     DISCUSSION OF THE PRIOR ART 
     Disclosed in Japanese Patent Laid-open Publication No. 2005-274204 is a beverage dispensing apparatus wherein an amount of beer stored in a beer barrel is supplied to a beverage supply conduit under pressure of carbonic acid gas from a gas cylinder and is cooled by a cooling coil to be dispensed from a faucet in connection to the beverage supply conduit. In the beverage dispensing apparatus, a pressure regulator is provided for adjustment of the supply pressure of carbonic acid gas to avoid excessive supply of beer from the barrel under the pressure of carbonic acid gas and to avoid obstacle in supply of the beer caused by shortage of the supply of carbonic acid gas. 
     In the beverage dispensing apparatus, a flow quantity measurement device is provided to measure an amount of beer flowing through the beverage supply conduit thereby to confirm an amount of beer remained in the barrel. The flow quantity measurement device is constructed to measure a propagation time of an ultrasonic wave between a pair of mutually opposed ultrasonic oscillators placed outside a conduit inclined from an upstream to a downstream at a portion of the beverage supply conduit. The flow quantity measurement device is, however, complicated in construction and is not suitable for mass production because of high manufacturing cost. In addition, contaminants accumulate at the attachment place of the ultrasonic oscillators. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an object of the present invention to provide a beverage dispensing apparatus wherein an amount of beverage remained in a beverage container is reliably measured and indicated without the provision of the conventional flow amount measurement device in the beverage supply conduit as described above. 
     According to the present invention, the object is accomplished by providing a beverage dispensing apparatus comprising beverage temperature measurement means for measuring a temperature of beverage stored in a closed beverage container, pressure measurement means disposed in a gas supply conduit supplying gas into the beverage container from a source of pressurized gas for measuring a gas pressure in the beverage container, a pressure regulator valve disposed in the gas supply conduit for regulating the pressure of gas supplied to the beverage container, discharge means for discharging an amount of beverage supplied thereto from a beverage supply conduit connected to the beverage container, wherein the pressure regulator valve is opened and closed in such a manner that the gas pressure in the container becomes a proper pressure calculated in accordance with a temperature of beverage measured by the temperature measurement means, wherein the beverage dispensing apparatus further comprises gas flow amount measurement means disposed in the gas supply conduit at a downstream of the pressure regulator valve for measuring a flow amount of gas supplied to the beverage container, calculation means for calculating an amount of beverage remained in the container or discharged from the container on a basis of the flow amount of gas measured by the gas flow amount measurement means, and display means for indicating the calculated amount of beverage remained in the container or discharged from the container. 
     In the beverage dispensing apparatus described above, an amount of gas supplied to the beverage container is measured by the gas flow amount measurement means without directly measuring the amount of beverage discharged from the container, and an amount of beverage remained in the container or discharged from the container is calculated on a basis of the measured flow amount of gas. With such calculation, the amount of beverage remained in the container or discharged from the container is accurately indicated on a display portion of the display means without being affected by bubbles appearing in the beverage when the beverage is foamy beverage such as beer. As the gas flow amount measurement means is provided to measure a flow amount of gas regulated to a proper pressure at the downstream of the pressure regulator valve, a measurement instrument of low pressure resistance can be adapted to measure the flow amount of gas. 
     In a practical embodiment of the present invention, it is preferable that the gas flow amount measurement means comprises means for measuring a mass flow rate of gas supplied to the beverage container per a unit time. In such an embodiment, means for measuring a temperature of gas supplied to the beverage container through the gas supply conduit is provided so that the calculation means acts to correct the measured mass flow rate in accordance with a gas pressure measured by the pressure measurement means and a gas temperature measured by the gas temperature measurement means for calculating an amount of beverage remained in the container or discharged from the container. In such an instance, the flow amount measured as the mass of gas is corrected in accordance with the pressure and temperature of gas to accurately calculate the amount of beverage remained in the container or discharged from the container. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, a preferred embodiment of a beverage dispensing apparatus according to the present invention will be described with reference to the accompanying drawing. The beverage dispensing apparatus  10  is provided therein with a beverage supply conduit  50  connected to a beer barrel T which is supplied with carbonic acid gas from a gas cylinder G. A faucet or tap  11  is mounted to an upper portion of the front panel of the beverage dispensing apparatus for pouring an amount of beer from the beverage supply conduit  50 . The gas cylinder G is provided with a pressure regulator valve for regulating the pressure of carbonic acid gas to a predetermined pressure (0.6 MPa (abs)). The faucet  11  includes a valve mechanism that is operated by a manual lever  12  to permit discharge of the beer supplied from the beer barrel T through the beverage supply conduit  50 . The beer is poured from nozzles  13  of the faucet  11  in a liquid condition and a bubble condition. 
     As shown in  FIG. 1 , the beverage dispensing apparatus  10  has a cooling water tank  20  installed therein to store an amount of cooling water for cooling the beer supplied from the barrel T through the beverage supply conduit  50  and a freezing device  30  for circulating refrigerant through a coiled evaporator  31  mounted within the water tank  20 . In operation of the freezing device  30 , the water stored in tank  20  is cooled by ice formed on the periphery of coiled evaporator  31 . 
     As shown in  FIG. 1 , a gas conduit  40  is housed in the rear portion of the housing of beverage dispensing apparatus  10  to supply the carbonic acid gas into the beer barrel T from the gas cylinder G. Disposed in the gas conduit  40  are a pressure regulator valve  41 , a gas pressure sensor  42 , a gas flow sensor  43 , a gas temperature sensor  44  in sequence from an upstream of the flow of gas. The gas conduit  40  is connected at its inlet end  40   a  to a conduit G 1  for supply of carbonic acid gas from the gas cylinder G and is connected at its outlet end  40   b  to a conduit G 2  for supply of the carbonic acid gas to the beer barrel T. The pressure regulator valve  41  is in the form of an electromagnetic valve to permit supply of the carbonic acid gas to the beer barrel T from the gas cylinder G when it is opened and to block supply of the carbonic acid gas to the beer barrel T when it is closed. The gas pressure sensor  42  is disposed in the gas conduit  40  at the downstream of the pressure regulator valve  41  to measure the pressure of carbonic acid gas supplied to the beer barrel T. 
     The gas flow sensor  43  is in the form of a mass flow rate sensor of the thermal type (MEMS flow sensor element made by Omuron Corporation) which is composed of a pair of thermopiles arranged at opposite sides of a heater. When the thermopiles received the flow of carbonic acid gas, the temperature of gas becomes lower at the windward of the heater and becomes higher at the leeward of the heater. Thus, a difference of the temperatures is detected as a difference of electromotive forces of thermopiles. When the difference of electromotive forces is detected, the flow rate of carbonic acid gas is measured in mass in a standard pressure condition (atmospheric pressure: 0.1013 MPa (abs) at a temperature (0°). In this embodiment, the flow rate of carbonic acid gas flowing through the gas conduit  40  per a unit time is measured in mass. Although the mass flow sensor was used as the gas flow sensor  43  in this embodiment, another gas flow sensor, for example, a mass flow sensor of the Coriolis type may be used as the gas flow sensor. The gas temperature sensor  44  is disposed in the gas conduit  40  at the downstream of gas flow sensor  43  to detect the temperature of carbonic acid gas supplied to the beer barrel T from the gas cylinder G. 
     The beverage supply conduit  50  is connected at its inlet end  50   a  to a conduit T 1  for supply of the beer from barrel T and is connected at its outlet end  50   b  to the faucet  11 . Disposed in the beverage supply conduit  50  are a beverage temperature sensor  51  and a liquid sensor  52  in sequence from the upstream of the flow of beer. The beverage temperature sensor  51  is provided to detect the temperature of beer supplied from barrel T. The temperature of beer detected by sensor  51  is deemed as the temperature of beer in barrel T. The liquid sensor  52  is provided to detect the flow of beer supplied through the beverage supply conduit  50  from the barrel T and to detect short of beer in the barrel T. An intermediate portion of beverage supply conduit  50  is in the form of a coiled cooling portion  53  housed in the water tank  20 . 
     As shown in  FIG. 2 , the beverage dispensing apparatus  10  is provided at its front with a display portion  60  having a plurality of parallel indication segments for displaying a calculated cumulative amount of beer discharged from the faucet  11  as shown in  FIG. 3(   a ) or  3 ( b ). In  FIG. 3(   a ), nine segments indicate the fact that a calculated cumulative amount of beer discharged from the barrel T is about 5 liter. In such a manner, a discharged amount of beer is indicated by the number of segments on the display portion  60 . Alternatively, an amount of beer remained in barrel T may be displayed by a plurality of parallel indication segments as shown in  FIG. 3(   c ) or  3 ( d ). In this case, the number of indication segments decreases in accordance with discharge of beer from barrel T. 
     As shown in  FIG. 4 , the beverage dispensing apparatus is provided with an electric controller E including a microcomputer  70  connected to sensors  42 ,  43 , 44 ,  51 ,  52  and to the pressure regulator valve  41  and the display portion  60 . As shown in  FIG. 4 , the computer comprises a memory  71  which stores a map for defining a proper pressure of carbonic acid gas to be filled in the beer barrel T in accordance with the temperature of beer in barrel T, processing means for calculating the proper pressure of carbonic acid gas based on the map in accordance with the temperature of beverage detected by sensor  51 , and control means for controlling open-and-close of the pressure regulator valve  41  in such a manner that the pressure of carbonic acid gas detected by sensor  42  becomes the proper pressure calculated by the processing means. The computer  70  further includes calculation means for correcting a mass flow rate of carbonic acid gas detected by gas flow sensor  43  in accordance with the pressure of carbonic acid gas detected by pressure sensor  42  and the temperature of carbonic acid gas detected by sensor  44  and for calculating an amount of beer discharged from barrel T on a basis of the correction of the mass flow rate of carbonic acid gas, and processing means for indicating the calculated cumulative amount of beer on the display portion  60 . 
     When a power switch (not shown) of the beverage dispensing apparatus is turned on, the freezing device  30  is activated to cool the water in cooling water tank  20 . Assuming that the temperature of beverage detected by sensor  51  is 15° C., the pressure of carbonic acid gas supplied from the gas cylinder G is regulated to about 0.30 Mpa (abs). When the manual lever  12  of faucet  11  is operated to pour the cold beer from the beverage supply conduit  50 , the pressure in the beer barrel T becomes lower. In such an instance, the pressure regulator valve  41  is opened under control of computer  70  in response to a detection signal of the gas pressure sensor  42  to permit supply of carbonic acid gas into the beer barrel T from the gas cylinder G and is controlled by the processing means of computer  70  to regulate the pressure of carbonic acid gas in the beer barrel T to a proper pressure in accordance with the temperature of beverage detected by sensor  51  on a basis of the map stored in the memory of computer  70 . 
     When the carbonic acid gas is supplied into the beer barrel T from the gas cylinder G in operation described above, the gas flow sensor  43  detects a flow amount of carbonic acid gas supplied into the beer barrel T through the gas conduit  40  per a unit time and applies the detection value to the computer. The detection value of the gas flow sensor  43  is measured in mass of the flow under the standard pressure (atmospheric pressure) at the standard temperature (0° C.), and the pressure of carbonic acid gas supplied to the beer barrel T is regulated to a proper pressure in accordance with the internal temperature of beer barrel T. As a result, the calculation means of computer  70  corrects the detection value of gas flow sensor  43  on a basis of the following formula and calculates a discharge amount V 2  of beer.
 
 V 2= V 1 ×P 1 /P 2 ×T 2 /T 1   (1)
 
     In this formula, V 1  is the detection value of gas flow sensor  43  converted in volume, P 1  is the standard pressure (atmospheric pressure), P 2  is a detection value of gas pressure sensor  42 , T 1  is the standard temperature 0° C. (273.2 K), and T 2  is a detection value of gas temperature sensor  44 . With the formula, the flow amount of carbonic acid gas can be calculated by multiplication of the detection value V 1  of gas flow sensor  43  with a pressure correction coefficient obtained by division of the standard pressure P 1  with the detection value P 2  of carbonic acid gas and a temperature correction coefficient obtained by division of the detection temperature T 2  of carbonic acid gas with the standard temperature T 1 . 
     Assuming that the flow amount V 1  of carbonic acid gas measured by gas flow sensor  43  during lapse of 2.5 minutes as shown by the reference character  a  is calculated as about 15 liter, the calculated flow amount V 1  is corrected by the following equation to calculate a discharge amount V 2  of the beer as the same amount of beer actually measured.
 
 V 2=15×0.1013/0.30×288/273.2=5.3
 
     Assuming that the temperature of beverage detected by sensor  51  has risen from 15° C. to 27° C. in a condition where the beer is not discharged, the pressure regulator valve  41  is opened and closed under control of the processing means of computer  70  in such a manner that the pressure of carbonic acid gas in the beer barrel T becomes a proper pressure 0.42 MPa (abs) in accordance with rise of the temperature of beverage detected by sensor  51 . As a result, the carbonic acid gas is supplied to the beer barrel T through the gas conduit  40  as shown by the reference character  b  in  FIG. 6 , and the flow amount of carbonic acid gas is measured by the gas flow sensor  43 . In such an instance, the flow amount of carbonic acid gas measured by the gas flow sensor  43  becomes about 15 liter before lapse of 4.5 minutes and becomes about 21 liter after lapse of 5 minutes. Thus, the amount of carbonic acid gas measured by the gas flow sensor  43  is corrected by the formula (1) as described below to calculate a discharge amount V 2  of beer from barrel T. 
     Discharge amount of beer before about 4.5 minutes:
 
 V 2=15×0.101 3/0.30×288/273.2=5.3
 
     Discharge amount of beer after 5 minutes:
 
 V 2=21×0.1013/0.42×300/273.2=5.5
 
     When the faucet  11  is operated to pour the beer in a condition where the gas pressure in barrel T is 0.42 MPa (abs), the flow amount of carbonic acid gas measured by sensor  43  after lapse of 9 minutes is calculated as about 42 liter as shown by the reference character  c . Accordingly, the discharge amount V 2  of beer from barrel T is calculated by correction described below on a basis of the formula (1).
 
 V 2=42×0.1013/0.41×293/273.2=11.1
 
The cumulative discharge amount of beer calculated as described above is approximately the same amount actually measured.
 
     When the pressure regulator valve  41  is closed under control of the computer  70  to restrict the supply of carbonic acid gas to the beer barrel T so that the pressure detected by sensor  42  decreases from 0.30 MPa (abs) to 0.25 MPa (abs) in accordance with the temperature of beer detected by sensor  51  in a condition where the faucet  11  is being operated to pour the beer, the flow amount of carbonic acid gas may not be measured by the gas flow sensor  43  as shown by the reference character  d  in  FIG. 7 . In such an instance, the flow amount of carbonic acid gas measured before 4.5 minutes is calculated as about  28  liter and is also calculated as 28 liter after lapse of 5.5 minutes. Accordingly, the discharge amount V 2  of the beer from barrel T is calculated by correction based on the foregoing formula (1) as described below. 
     Discharge amount of beer before 4.5 minutes:
 
 V 2=28×0.1013/0.30×288/273.2=9.9
 
     Discharge amount of beer after about 5.5 minutes:
 
 V 2=28×0.1013/0.25×288/273.2=11.9
 
The cumulative discharge amount of beer calculated as described above is approximately the same amount as that actually measured even when the flow amount of carbonic acid gas may not be measured by the gas flow sensor  43  in a condition where the carbonic acid gas is not supplied to the gas conduit  40  to decrease the pressure in beer barrel T.
 
     As is understood from the above description, the flow amount of carbonic acid gas supplied to the beer barrel T is measured by the gas flow sensor  43 , and the discharge amount of beer from barrel T is calculated on a basis of the measured flow amount of carbonic acid gas or the calculated discharge amount of beer is subtracted from the initial amount of beer stored in barrel T to calculate an amount of beer remained in barrel T thereby to indicate the discharge amount or remained amount of beer on the display portion  60  as shown in  FIG. 3 . 
     Although in the foregoing embodiment, the beverage temperature sensor  51  has been provided in the beverage supply conduit  51  to detect the temperature of beer in barrel T, a temperature sensor for detection of an ambient temperature of the beer barrel T may be provided to calculate the temperature of beer in barrel T by conversion of its detection value. In addition, the plurality of segments for indication of an amount of beer discharged from barrel T or remained in barrel T may be substituted for another display visible at a glance. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  is a side view of a beverage dispensing apparatus according to the present invention; 
       FIG. 2  is a front view of the beverage dispensing apparatus shown in  FIG. 1 ; 
       FIG. 3  is a view of indication on a display portion of the beverage dispensing apparatus shown in  FIG. 1 ; 
       FIG. 4  is a block diagram of an electric control apparatus for the beverage dispensing apparatus shown in  FIG. 1 ; 
       FIG. 5  is a graph showing a proper gas pressure in a beer barrel; 
       FIG. 6  is a graph showing a relationship between a calculated flow amount of carbonic acid gas detected by a gas flow sensor in the beverage dispensing apparatus and a calculated discharge amount of beer after correction; 
       FIG. 7  is a graph showing a relationship between a calculated flow amount of carbonic acid gas detected by a gas flow sensor in the beverage dispenser and a calculated discharge amount of beer after correction.