Abstract:
The present invention deals with determining the level of fluid in a container. Typically, a beverage container containing a liquid will absorb heat energy from the surrounding environment at a greater rate than a gaseous component in the headspace of the beverage container. Thus, as the liquid is drawn from a beverage container a greater headspace results. If a thermometric measuring device is employed along the height of the beverage container the volume may be determined by observing the difference in the temperature along the height of the beverage container. In practice, a beer keg may exhibit a difference of as much as 9 degrees Fahrenheit on the exterior surface of the beer keg when measured at the headspace as opposed to the area where the liquid is present in the beverage container.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to determining the level of fluid in a container and the like.  
           [0003]    2. Description of the Art Practices  
           [0004]    U.S. Pat. No. 5,655,839 issued to Schmidt, et al. Aug. 12, 1997 describes an IR temperature sensor that comprises a sealed housing containing an inert gas atmosphere and enclosing a detector for conversion of heat radiation into an electrical signal, an optical system which images the heat radiation emanating from an object onto the detector, a heat-conducting temperature equalization element which maintains the detector and the optical system at a common temperature, and a temperature sensor which measures the temperature of the temperature equalization element. The sealed housing protects the sensor from the external environment and maintains uniform temperature between the optical system and the sensor.  
           [0005]    Further information concerning infrared temperature sensors is found in a brochure entitled Raynger® ST™ that describes ST30 Pro™ Standard and ST30 Pro™ Enhanced noncontact thermometers. The ST30 Pro™ Standard and ST30 Pro™ Enhanced noncontact thermometers are available from Raytek Corporation 1201 Shaffer Road Post Office Box 1820 Santa Cruz, Calif. 95061-1820.  
           [0006]    U.S. Pat. No. 4,362,645 that issued to Hof, et al. Dec. 7, 1982 describes temperature-indicating compositions of matter. U.S. Pat. No. 4,362,645, in particular describes stable compositions of matter which change color sharply upon a transition from a liquid state to a solid state or from a solid state to a liquid state, which change of state is at substantially a predetermined temperature corresponding to a temperature to be measured.  
           [0007]    The constituents of the Hof, et al. compositions of matter comprise: 1. a solvent (I) consisting of a single substance or a mixture of substances and adapted to change from a solid state at substantially a predetermined temperature to a liquid state and 2. an indicator system (II) consisting of one or more substances different from (I), characterized in that (a) (II) is soluble in (I) when the latter is in the liquid phase, and (b) (II) changes color visible to the naked eye when (I) passes from the solid to the liquid phase or from the liquid to the solid phase. Thermometers containing said stable compositions of matter are also disclosed.  
           [0008]    U.S. Pat. No. 4,339,207 also to Hof, et al. which issued Jul. 13, 1982 describes a temperature indicating device is disclosed comprising: (a) a flat or gradually curved heat-conducting carrier having one or more cavities, each substantially filled with a composition of matter; or in the alternative, with (1) a composition of matter which changes from opaque to transparent upon a corresponding change from solid to liquid on top of an (2) indicator means located at the bottom of the cavity; said composition of matter, whether novel or not, being substantially without impurities and containing a substantially spherical void space between the bottom of the cavity; and (b) a transparent cover sheet means in sealing engagement with the heat conducting carrier means overlying and above the cavity, which spherical void space acts to magnify the color change if the novel compositions of matter are present or the presence of an indicator means upon melting of the compositions of matter in the cavity.  
           [0009]    The compositions of matter of Hof et al., are further described as changing color sharply upon a transition from a liquid state to a solid state or from a solid state to a liquid state, which change of state is at substantially a predetermined temperature corresponding to a temperature to be measured.  
           [0010]    U.S. Pat. No. 4,232,552 issued to Hof, et al. Nov. 11, 1980 discloses temperature-indicating compositions of matter. The Hof, et al. compositions Novel and stable compositions of matter are disclosed which change color sharply upon a transition from a liquid state to a solid state or from a solid state to a liquid state, which change of state is at substantially a predetermined temperature corresponding to a temperature to be measured. The constituents of the novel compositions of matter comprise: 1. a solvent (I) consisting of a single substance or a mixture of substances and adapted to change from a solid state at substantially a predetermined temperature to a liquid state and 2. an indicator system (II) consisting of one or more substances different from (I), characterized in that (a) (II) is soluble in (I) when the latter is in the liquid phase, and (b) (II) changes color visible to the naked eye when (I) passes from the solid to the liquid phase or from the liquid to the solid phase. Thermometers containing stable compositions of matter are also disclosed in U.S. Pat. No. 4,232,552.  
           [0011]    Seiden, et al., in U.S. Pat. No. 5,426,593 issued Jun. 20, 1995 is directed to a device which measures the oxygen component of a beverage gas using a specific oxygen probe, ultrasonic degassing, a special valving technique, and microprocessor based software. The measurement is made in the gaseous state in a two-chamber system.  
           [0012]    The device of Seiden, et al., is controlled by an electronic console that is built around a microprocessor which sequences and times the valves, receives the data from the oxygen probe and its accompanying temperature compensation circuit, and displays the data. An alternative method is to use several chambers and one pass. Additional chambers may be used to increase the speed of the test, control interferences, or aid in identifying gases other than the oxygen component. The device may also have an interface piercing head manifold that allows carbon dioxide and oxygen to be tested in the same container and in one preparation. The invention also relates to specific gas measurements with non-specific type measurements and the general techniques can be applied to environmental problems that involve oxygen demand and respir-ation of bacteria.  
           [0013]    U.S. Pat. No. 6,119,464 issued to Nakayama, et al. on Sep. 19, 2000 describes beverage servers and controlling methods for beverage servers. More particularly, Nakayama, et al. discloses a beverage server comprising a tank containing water serving as a coolant and a coiled beverage duct through which beer or other beverage flows and cooling means fitted to a portion of the wall of the tank so as to rapidly cool and serve beer or other beverage discharged from the storage container. The inner wall of the tank near the portion where the cooling means is fitted is made of a material having a high thermal conductivity, whereas the inner wall of the tank near the beverage duct is made of a material having a low thermal conductivity. A sensor is provided near the beverage duct to obtain information for controlling the cooling means. This simple beverage server assures stable serving of beverage at a suitable temperature. Another sensor is provided near a portion of the tank wall where the cooling means and a controller to controls the action of the cooling means based on the information from the sensors are also provided. The cooling means works at full capacity when one or both of the sensors have detected the melting of the coolant. This eliminates the risk of trouble due to cooling capacity deficiency even after a long interruption of cooling.  
           [0014]    Furuhashi, et al., in U.S. Pat. No. 5,165,569 issued Nov. 24, 1992 recites a keg body for retaining draft beer substantially has adiabatic structure, in which draft beer filled in the keg body is kept cool. A part of the keg body is provided with a face which is not heat-insulated and this face is utilized as a cooling face. In case of necessity, beer is cooled from the outside through the cooling face to keep cool draft beer inside the keg body.  
           [0015]    To the extent that the foregoing patents are relevant to the present invention they are herein incorporated by reference. Temperatures herein are given in degrees Fahrenheit and pressures are in gauge Kpa. Ratios and ranges may be combined.  
         SUMMARY OF THE INVENTION  
         [0016]    The present invention describes a method for determining the level of fluid in a container comprising:  
           [0017]    obtaining a container having a first fluid region therein;  
           [0018]    a first fluid being present at an original level in said first fluid region of said container;  
           [0019]    said container, for when in use, having said first fluid at least partially removed from said container thereby forming a second fluid region;  
           [0020]    placing on at least one exterior surface of said container at least one temperature-measuring device;  
           [0021]    at least one said temperature-measuring device being located in a region of said container where said second fluid region is formed by removal of said first fluid;  
           [0022]    initially observing a first temperature in said first fluid region of said container when said first fluid is present in said first fluid region of said container;  
           [0023]    subsequently observing a second temperature in said second fluid region of said container after a potion of said first fluid has been removed;  
           [0024]    correlating the difference between said first temperature and said second temperature to the level of said first fluid in said container.  
           [0025]    Yet another aspect of the invention is a fluid dispensing assembly comprising:  
           [0026]    a sealed container, for when in use, containing a liquid under pressure;  
           [0027]    said sealed container having an exterior surface;  
           [0028]    said exterior surface of said sealed container having a heightwise dimension and a widthwise dimension; and  
           [0029]    at least one temperature-measuring device positioned on said heightwise dimension of said exterior surface.  
           [0030]    Another aspect of the invention is a fluid dispensing assembly comprising:  
           [0031]    a sealed metal beer barrel, for when in use, containing beer under pressure;  
           [0032]    said metal beer barrel having an exterior surface;  
           [0033]    said exterior surface of said metal beer barrel having a heightwise dimension and a generally circular cross-sectional dimension; and  
           [0034]    at least one temperature-measuring device positioned on said heightwise dimension of said exterior surface of said metal beer barrel.  
           [0035]    Yet another embodiment of present invention is a temperature-measuring device mounted on a flexible band.  
           [0036]    A further embodiment of present invention is a method of obtaining the level of a liquid or a gas in a container including the steps of:  
           [0037]    obtaining the temperature at a selected region of said container containing said liquid or said gas;  
           [0038]    comparing the temperature at said selected region of said container with a profile of temperatures corresponding to a liquid level of said fluid in a vessel and the temperature corresponding to a gas level in the vessel; and,  
           [0039]    determining whether the temperature in said container indicates the level of said liquid or said gas.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0040]    The foregoing and other features of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, wherein:  
         [0041]    [0041]FIG. 1 is a partial cross-sectional perspective view showing a first embodiment of a beer keg of the invention;  
         [0042]    [0042]FIG. 2 is a longitudinally cross-sectional view showing a beer keg having draft beer in the beer keg;  
         [0043]    [0043]FIG. 3 is a view showing a beer keg;  
         [0044]    [0044]FIG. 4 is a thermometric fastening device according to the invention; and,  
         [0045]    [0045]FIG. 5 is a view of another embodiment of the invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0046]    In FIG. 1, a beer keg  1  according to a first embodiment of the invention is shown. The beer keg  1  is generally cylindrical.  
         [0047]    As shown in FIG. 2, the beer keg  1  is a container made of thin stainless steel plate, and having a mouthpiece  2  and a bottom. The beer keg  1  is prepared by welding an inner cylinder upper plate  3 , the outer cylinder shell  6 , and an outer cylinder lower plate  9 .  
         [0048]    The outer cylinder shell  6  is in a cylindrical form and is integrally sealed, at its upper and lower edges with the inner cylinder plate  3  and the outer cylinder plate  9 , respectively, by TIG welding. In this embodiment, the mouth piece  2  is mounted on the center of the inner cylinder plate  3 . A down tube  13  shown in FIG. 3 is inserted into the beer keg  1  through the mouth piece  2 .  
         [0049]    The down tube  13  is a tube for providing draft beer into the inside of the beer keg  1  and also ejecting draft beer from the beer keg  1 . The down tube  13  has a carbon dioxide-valve (not shown) and a beer valve (not shown) and is screwed in the mouthpiece to be fixed.  
         [0050]    The keg outer cylinder  6  is formed of an outer cylinder shell  8  and an outer cylinder lower plate  9 . The outer cylinder shell  8  has an upper grip  7  at its upper opening edge and a keg leg  10  at its lower opening edge, respectively. Both upper and lower edges are bent inwardly. The diameter of the upper edge is slightly smaller than that of the lower edge, but the upper and lower portions of the outer cylinder shell  8  may be reversible upside down.  
         [0051]    At the proper standing posture of the outer-cylinder shell  8 , the upper edge acts as the upper grip  7  and the lower edge operates as the keg leg  10 . At the inverted posture thereof, the upper edge acts as the keg leg  10  and the lower edge acts as the upper grip  7 .  
         [0052]    A\ shown in FIG. 1, a plurality of thermometric measuring devices  12  are provided on the outer cylinder shell  8 . The thermometric measuring devices  12  are designated as  12 A,  12 B,  12 C, and  12 D. The thermometric measuring devices  12  are so designated by the appended letter to show the location on the keg outer cylinder  6 .  
         [0053]    Several eutectic materials are disclosed in U.S. Pat. No. 4,362,645 that issued to Hof, et al. Dec. 7, 1982 as well as the remaining cited Hof, et al. patents. Similar eutectic may be formulated from foregoing disclosures to provide a suitable temperature range for determining the temperature within a container such as a beer barrel.  
         [0054]    The thermometric measuring devices  12  are first located along the height of the keg outer cylinder  6  and generally correspond to a level of 10 percent of maximum fluid content of the beer keg  1 , 25 percent of maximum fluid content of the beer keg  1 , and 75 percent of maximum fluid content of the beer keg  1 . Alternatively, thermometric measuring devices  12  are conveniently located at a point from 5% to 35% of the maximum original fluid level in said first fluid region of said container.  
         [0055]    The thermometric measuring devices  12  are also located circumferentially around the keg outer cylinder  6 . Conveniently, the thermometric measuring devices  12  located around the circumference of the keg outer cylinder  6  are two, three, four, five, six, seven, or eight in number.  
         [0056]    The thermometric measuring devices  12  located around the circumference of the keg outer cylinder  6  are to aid in the determination of fluid level. As the beer kegs are quite heavy and when tapped with associated piping the movement of beer kegs is difficult. Also the movement of the beer kegs into a cooler of confined dimensions makes it difficult to move the kegs within a cooler. Accordingly, a plurality of thermometric measuring devices  12  makes it easier to see at least one of the thermometric measuring devices  12 .  
         [0057]    When for example, there are two of the thermometric measuring devices  12  circumferentially located on the keg outer cylinder  6  either of the two the thermometric measuring devices  12  may be read. If there are three of the thermometric measuring devices  12  circumferentially located on the keg outer cylinder  6  and each is located approximately 120 degrees apart it will be easier to see at least one of the thermometric measuring devices  12 .  
         [0058]    The thermometric measuring devices  12  are conveniently placed in as close a contact as is possible with keg outer cylinder  6 . The thermometric measuring devices  12  may be adhesive backed to permit relatively intimate contact with the keg outer cylinder  6 . Alternatively, the thermometric measuring devices  12  may be affixed to the keg outer cylinder  6  by means of a transparent pressure sensitive adhesive tape (not shown). The transparent pressure sensitive adhesive tape permits viewing of the thermometric measuring devices  12  to determine the temperature and accordingly the volume level of the beer keg  1 .  
         [0059]    The outer cylinder lower plate  9  is provided with a nozzle  11  having a valve. After the valve is opened and the nozzle  11  is connected to a vacuum pump (not shown) air or liquid in the beer keg  1  is removed. In this manner the beer keg  1  may be cleaned. Then, the valve is then closed to permit filling of the beer keg  1 .  
         [0060]    In a brewery, there is a line where a beer keg  1  incorporated with the down tube  13  is automatically washed and draft beer is automatically filled in the beer keg  1 . Similarly, the beer keg  1  of the present invention is automatically washed and filled with draft beer by using the above-mentioned line. The beer keg  1  filled with the draft beer is stored in a refrigerator for shipping to forcibly cool beer in the beer keg  1  through the face Cz. In shipping, as shown in FIG. 3, the upper face of the inner cylinder upper plate  3  of the beer keg  1  is covered with an adiabatic mat  14  to keep low temperature. The beer keg  1  is kept in a proper standing posture, so that temperature of draft beer filled in the beer keg  1  does not substantially rise due to the fact that draft beer is heat-insulated by the vacuum layer between the beer keg  1  and the outer cylinder shell  8 . After the beer keg  1  of the present invention is supplied to and stored in a tavern, beer is kept cool in a refrigerator in an inverted posture or horizontal posture. Draft beer is cooled through the face Cz of the inner cylinder upper plate  3 , so that the draft beer can be effectively forcibly cooled.  
         [0061]    In the beer keg  1  described in the present invention, the upper end hole of the outer-cylinder shell  8  is reduced in diameter to be smaller than the lower end hole, but either one of the upper and lower edges of the outer cylinder shell  8  becomes a grip or keg leg, so that the beer keg  1  can be placed without distinguishing upper and lower portions. On sale of draft beer at a tavern, beer is supplied in a conventional manner to a pitcher and so on through the down tube  13  while carbon dioxide is injected with pressure, wherein the beer keg  1  is vertically positioned to locate the mouth piece upwardly. To keep the draft beer cool during the sale is made by inserting a cooling agent a between the adiabatic mat  14  and the inner cylinder upper plate  3 .  
         [0062]    As best seen in FIG. 4, is a temperature-measuring device  40  mounted on a flexible band  44 . The temperature-measuring device  40  is conveniently secured to a flexible band  44  such that the thermally sensitive portion of the temperature-measuring device  40  may be exposed to the outer side of a beer barrel. The temperature-measuring device  40  is conveniently insulated so that the ambient temperature such as in a region of low humidity as a refrigerator or refrigerator compartment will not interfere with the temperature-measurement and thus determination of level of fluid in the beer barrel.  
         [0063]    The flexible band  44  may be an endless band such as formed form an elastomeric material. In a preferred embodiment, the flexible band  44  is a non-endless belt that is secured with a hook  52  and eye  54  fastener (Velcro).  
         [0064]    As best seen in FIG. 5 is a conventional mercury thermometer  70 . The mercury thermometer  70  to a beer barrel. A small amount of an insulating material  72  is placed on the ball of the thermometer to ensure that is the temperature of the beer barrel and not the ambient temperature in the refrigerator that is observed.  
         [0065]    In use, as best seen in FIG. 2, is the level of beer  80  in a beer keg  1 . It is observed that the beer  80  within the beer keg  1  has excellent heat flow characteristics when compared to the gas in the headspace out of the liquid level of the beer. As the beer  80  is withdrawn from the beer keg  1  through the down tube  13 , increased headspace occurs. The gas in the headspace will typically be warmer than the liquid in the beer keg  1 . As such a temperature-measurement in the region of that headspace will result in a higher temperature than that in the liquid.  
         [0066]    As best seen in FIG. 3, as the beer  80  is drawn from the level of  12 D to  12 C the heat flow characteristics will cause the thermometric measuring device  12 D to increase in temperature and to change color. The thermometric measuring device  12 C will maintain its temperature and not change color until the liquid level drops to the region below thermometric measuring device  12 C.  
         [0067]    As the tavern owner will desire to know only the level of various kegs of beer it is possible to make such determination by observing where the colder temperature region of the beer keg is located. Thus, when the temperature of the beer keg  1  indicates that the colder temperature is only at the lower  10  percent of the beer keg  1  it is easily determined that the beer keg  1  should be changed prior to a busy evening. Of course, the temperature indicator on the beer keg  1  is also more than adequate to determine which are kegs are of sufficiently low temperature from which to serve the beer. The present invention also provides an opportunity for loss prevention or inventory control by tavern keeper.  
         [0068]    In a situation where the mercury thermometer is utilized, the thermometer may be moved around on the beer keg  1 . The present invention may also utilize the eutectic strips to determine during the course of the evening as to how far the beer has been depleted.  
         [0069]    As the one further embodiment, is possible to utilize an infrared thermometric device to make the determination of level of liquid in the beer keg  1 . However, it is preferred that the thermometric temperature-measuring device be permanently affixed to the container so that it is readily available for the determination of volume and temperature.