Abstract:
An automatic liquid metering apparatus is disposed with at least a liquid concentrate motor pump with a tube connected thereto and at least a diluting water motor pump with a tube connected thereto where the turning of the pumps is timed by a microprocessor to control the amounts of liquid concentrate and diluting water to be dispensed. The outlet tubing of the pump is connected to the outlet of liquid concentrate and diluting water via a check valve. A lift mechanism is provided at the concentrate/diluting water outlet, which allows the choice of small cup, medium cup or large pot by ascending or descending to the proper height. The stop point of the lift mechanism is microprocessor controlled to prevent the spurting of dispensed liquid concentrate and diluting water due to great distance between their outlet and the rim of cup to ensure sanitary and smooth dispensing of fluids. This invention features precision dispensing of concentrate and diluting water and low manufacturing costs.

Description:
BACKGROUND OF INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The advent of biotechnology allows 5 grams of beverage concentrate to be made into 150 grams of drink. Thus a liquid metering apparatus needs to be designed with precision microprocessor to meet the consumer demands. The new metering apparatus design disclosed in this invention features a concentrate pump and a diluting water pump with respective outlet connected to the outlet of liquid concentrate and diluting water via a check value tubing. The pump outlet is disposed with at least a set of lift mechanism that ascends or descends in response to the rotation of pump motor which is under microprocessor control by the choice of small cup, medium cup or large pot. The vertical position of the small cup, medium cup and large pot as elevated or dropped by the lift mechanism is determined by the contact stop point as controlled by the rotation of pump motor, so liquid concentrate and diluting water dispensed into the cup or pot will not spurt out due to long distance between the outlet of liquid and the rim of cup. After the concentrate pump is stopped, a pressing mechanism will operate in order to squeeze out and then suck in remaining liquid concentrate from the outlet of tubing, such that the outlet of tubing will not contain any liquid drop. The apparatus disclosed herein ensures sanitary and smooth dispensing of fluids and features precision metering and low manufacturing costs.  
         [0003]     2. Description of the Prior Art  
         [0004]     For a long time, beverage drinks are either freshly squeezed or made from powder to keep their freshness and original flavor. However it is not exactly convenient for consumers to prepare drinks in such a manner.  
         [0005]     Modern life stresses quality and speed. As the demands for liquid beverages rise, it is becoming more prevalent to dispense drinks by quickly diluting concentrate with water. The trend is also using modern technology to produce high quality liquid concentrate that retains the original flavor at lower costs. Such liquid concentrate is easy to dispense where small amount of concentrate can be made quickly into large amount of ready-to-drink beverage to satisfy the needs of consumers. In line with the age of concentrate beverage, the present invention features motor pump and check valve to meet the requirements for precision dispense of concentrate and address the drawbacks of prior art.  
       SUMMARY OF INVENTION  
       [0006]     The primary object of the present invention is to provide an automatic liquid metering apparatus which allows precision metered supply of liquid concentrate and diluting water through microprocessor programming to meet user&#39;s needs for quick, metered and sanitary dispensing of beverage.  
         [0007]     To achieve the aforesaid objects, the automatic liquid metering apparatus of the present invention features a control process with a microprocessor to control the running time of motor pump, check valves and a lift mechanism, characterized in which the concentrate supply of the metering apparatus is connected to the inlet of motor pump via a tubing, the diameter of pump inlet is greater than that of pump outlet, and the pump outlet is connected to an internal tubing of lift mechanism via a check valve. When the motor stops running, the check valve is closed to stop the fluid from leaking or backflow due to siphonage. Also, with the inlet size of concentrate pump being greater than its outlet that more liquid comes in than discharge, it totally prevents the uneven flow of concentrated liquid in the pump caused by the presence of vacuum inside. The pump is akin to a syringe that draws in fluid rapidly and creates vacuum in the process before the syringe is completely filled. For the pumping of diluting water, regular pump or solenoid valve will work due to the better fluidity of diluting water. With the metered supply of liquid concentrate and diluting water, consumers can press the desired buttons to get the properly diluted drink.  
         [0008]     Another feature of the present invention provides a new design, characterized in which the metering apparatus is disposed with at least a liquid pump connected to a concentrate tubing and a diluting water pump connected to a diluting water tubing. The outlets of the pumps are respectively connected to the outlet of liquid concentrate and diluting water via a check valve tubing. A motor-run lift mechanism is provided at the outlet that ascends or descends according to the button selected for small cup, medium cup or large pot, and stops when the positioning point switch for the selected cup or pot is touched under the control of microprocessor. This design prevents the spurting of dispensed fluid into the cup or pot due to long distance between the outlets of liquid concentrate and diluting water and the rim of cup or pot. The provision of a lift mechanism at the fluid outlet to ensure sanitary and smooth dispensing is a feature of the invention.  
         [0009]     In addition, when the concentrate pump stops pumping, there will be some liquid concentrate remaining at the outlet of tubing and forming a semi-sphere shaped drop there. After some time later, say ten minutes or more, the semi-sphere shaped drop of liquid concentrate will start drying out from its appearance due to air flow and temperature. As a result, liquid concentrate will tend to spray toward everywhere when next time the concentrate pump is working again. Therefore, the present invention discloses a pressing mechanism which will compress part of the tubing to squeeze some remaining liquid concentrate out of the outlet, and then let the tubing returning back its original circular shape so as to suck the liquid concentrate located at the outlet back to the interior of tubing. As a result, there will be no more semi-sphere shaped drop remaining at the outlet of tubing. The outlet will become a plane and thus the remaining liquid concentrate inside the tubing will not be easily influenced by the drying effect due to air flow or temperature. Therefore, the liquid concentrate will flow smoothly and vertically toward the cup every time when the concentrate pump operates. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a diagram showing the layout of an automatic liquid metering apparatus according to the invention.  
         [0011]      FIG. 2  is a control panel diagram showing the button selections of an automatic liquid metering apparatus according to the invention.  
         [0012]      FIG. 3A  is a diagram showing a lift mechanism at the outlets of concentrate and diluting water in an automatic liquid metering apparatus according to the invention.  
         [0013]      FIG. 3B  is a diagram showing an electromagnetic actuated lift mechanism at the outlets of concentrate and diluting water in an automatic liquid metering apparatus according to the invention.  
         [0014]      FIG. 3C  is a diagram showing a manually operated lift mechanism at the outlets of concentrate and diluting water in an automatic liquid metering apparatus according to the invention.  
         [0015]      FIG. 4  is a diagram showing the movement of concentrate and diluting water in an automatic liquid metering apparatus according to the invention and the seats for small cup, medium cup and large pot.  
         [0016]      FIG. 5A  is a diagram showing the concentrate bag of the invention full.  
         [0017]      FIG. 5B  is a diagram showing the trigger of alarm switch when the concentrate bag of the invention becomes empty.  
         [0018]      FIG. 6  is a diagram showing the pressing mechanism squeezing the tubing of liquid concentrate according to the automatic liquid metering apparatus of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0019]     The automatic liquid metering apparatus of the invention features the use of microprocessor for precision control of motor pumps and check valves. In the process of drawing and discharging fluid, the running time of motor pump is under microprocessor control to supply precise amounts of liquid concentrate and diluting water for mixing. In the pump for liquid concentrate with less fluidity, its inlet is designed with larger diameter than its outlet such that sufficient amount of liquid is drawn in instantly without creating a vacuum state that causes unstable flow. The control process is linked up in the following fashion: the outlet of liquid concentrate is connected to the inlet of motor pump via a tubing; the outlet of motor pump is connected to the outlet of concentrate jacket assembly of lift mechanism via a check valve tubing; the outlet of diluting water tank is connected to the inlet of motor pump via a pump tubing; the pump outlet tubing is connected to the outlet of diluting water jacket assembly of lift mechanism via a check valve tubing; where accurate amount of drink is supplied based on the choice of small cup, medium cup or large pot provided at the concentrate/diluting water outlet of lift mechanism. For metered supply of liquid drink, place the cup of desired size and then press the button indicating the selected cup on the microprocessor control panel. Next, select the type of liquid desired (D, R or T), and then the amount of liquid concentrate desired. Subsequently, start the lift mechanism where the lifting gear will descend and stop at the point as set by the microprocessor. At this point, the liquid concentrate motor starts to run to supply liquid concentrate as timed by the microprocessor. When the liquid concentrate motor stops, the diluting water motor starts to run to supply water as timed by the microprocessor. After the supply of diluting water stops, the lift mechanism under the control of microprocessor rises to the point where the lifting gear motor stops, and the drink of fixed volume can be taken out. In addition, the lift mechanism disposed at the concentrate/water outlet that ascends or descends the small cup, medium cup or large pot selected to a proper height from the concentrate/water outlet prevents the spurting of dispensed liquid to ensure sanitary and smooth supply of drink. That is, consumers only need to press a few buttons to get the drink of desired concentration and amount.  
         [0020]     Referring to FIGS.  1 ˜ 6 , the liquid metering apparatus of the invention comprises at least a power indicator  101 , D concentrate motor button  102 , R concentrate motor button  103 , T concentrate motor button  104 , D concentrate timing motor button  105 , R concentrate timing motor button  106 , T concentrate timing motor button  107 , function code and temperature indicator  108 , large pot button  109 , medium cup button  110 , small cup button  111 , light button  112 , strong button  113 , light button  114 , strong button  115 , light button  116 , strong button  117 , start button  118 , stop button  119 , hot water button  120 , diluting water tank heater  121 , concentrate outlet  122 , body  123 , motor stand  124 , mounting mechanism  125 , slide space  126 , small cup positioning switch  127 , medium cup positioning switch  128 , large pot positioning switch  129 , liquid jacket assembly stop point  130 , liquid jacket assembly  131 , heat insulation pad  132 , diluting water tubing  133 , helical gear shaft  134 , lift balancing shaft  135 , gear sleeve  136 , liquid jacket assembly connecting shaft  137 , lifting gear motor  138 , lift assembly holder  139 , small cup seat  140 , medium cup seat  141 , large pot seat  142 , diluting water tank  143 , liquid tubing  144 , concentrate check valve  145 , diluting water check valve  146 , diluting water pump or solenoid valve  147 , concentrate pump inlet  148  (large diameter), concentrate pump outlet  149  (small diameter), top cover  150 , diluting water tank lid  151 , front lid  152 , concentrate container  153 , adaptor of concentrate bag  154 , housing base  155 , heating plate  156 , concentrate refill inlet cap  157 , concentrate refill inlet  158 , spring hook  159 , microprocessor control panel  160 , D concentrate pump  161 , R concentrate pump  162 , T concentrate pump  163 , front lid fastener  164 , concentrate level alarm switch  165 , electromagnetic actuator  166 , electromagnetic actuator shaft  167 , fixing bolt  168 , fixing seat  169 , sliding gap  170 , lifting positioning axle  171 , lifting swinging arm  172 , elastic plate  173 , small cup positioning point  174 , medium cup positioning point  175 , fixing shaft  176  for lifting swinging arm, spring  177 , manually actuated arm  178 , horn  179 , motor  180  of pressing mechanism, axle  181 , base  182 , right bracket  183  of pressing mechanism, pressing mechanism  184 , stopping switch  185  of motor, left bracket  186  of pressing mechanism, semi-sphere shaped drop  187  located at the outlet of silicon tubing, liquid concentrate drops  188  squeezed out from the outlet of silicon tubing, liquid concentrate  189  sucked back to interior of the tubing when the tubing returns back to its original circular shape, and screws  190 ,  191  and  192 . The assembly of aforesaid components provides metered amount of concentrate to meet the user demand.  
         [0021]      FIG. 1  is the front view of an automatic liquid metering apparatus according to the invention.  
         [0022]     The automatic liquid metering apparatus comprises a body  123  with a top cover  150  thereon. A diluting water tank lid  151  is disposed at the upper left side of the top cover  150 , and a microprocessor control panel  160  is disposed beneath the top cover  150 . The buttons of the microprocessor control panel  160  are depicted in  FIG. 2 . Beneath the microprocessor control panel  160  are a concentrate outlet  122  and liquid jacket assembly  131 . The housing base  155  is provided with a beverage container stand disposed with a small cup seat  140 , medium cup seat  141  and large pot seat  142 . A front lid  152  with a fastener  164  is disposed at the right front side of body  123 . To replace the bag in the concentrate container  153 , press on the front lid fastener  164  to remove the front lid  152  and expose the concentrate container  153 . A concentrate bag adaptor  154  is located at the lower part of concentrate container  153  and connected to the concentrate timing motor. A heating plate  156  is seated on the housing base  155  to keep the unused beverage in the large pot warm.  
         [0023]      FIG. 2  shows the microprocessor control panel buttons of the liquid metering apparatus.  
         [0024]     The buttons of the microprocessor control panel  160  located on the body  123  of the liquid metering apparatus consist of a power indicator  101 , D concentrate motor button  102 , R concentrate motor button  103 , T concentrate motor button  104 , D concentrate timing motor button  105 , R concentrate timing motor button  106 , T concentrate timing motor button  107 , function code and temperature indicator  108 , large pot button  109 , medium cup button  110 , small cup button  111 , light button  112 , strong button  113 , light button  114 , strong button  115 , light button  116 , strong button  117 , dispense start button  118 , stop button  119 , and hot water button  120 . Its control process is illustrated using the example of making a small cup of drink: to obtain a drink from concentrate, press small cup button  111 , then D concentrate timing motor  10  and light button  112 . Next press dispense start button  118 , upon which, the lifting gear  138  turns to descend the lift mechanism to the small cup positioning switch  127 . Then the microprocessor starts to drive the D concentrate timing motor pump  161  to turn and supply liquid concentrate until timeout and starts to drive the diluting water motor pump or solenoid valve  147  until timeout as dictated by the pressing of small cup button  111 . Afterwards, the lift mechanism ascends under the reverse rotation of microprocessor-controlled lifting gear motor  138  and stops at the position of large pot positioning switch  129 , and the drink may be taken out.  
         [0025]     If the start button is pressed by mistake in the process, user can press the stop button  119 . There is also a hot water button  120  that instructs the diluting water pump  147  to supply hot water or cold water. The D concentrate motor button  102 , R concentrate motor button  103  and T concentrate motor button  104  are pressed to test the discharge and flow rate of concentrate under the working of concentrate motor pump. The D concentrate timing motor button  105 , R concentrate timing motor button  106 , and T concentrate timing motor button  107  are under microprocessor control to drive and time the running of motor. D, R, T represents the type of concentrate. There may be one type or a plurality of concentrates in the liquid metering apparatus.  
         [0026]     The function code and temperature indicator  108  is also microprocessor controlled. When temperature display stops when the timing of function is set. After the timing of function is set, the temperature indicator displays the temperature of hot water in diluting water tank.  
         [0027]     In addition, after selecting the large pot button  109 , medium cup button  110  or small cup button  111 , user may select the D concentrate timing motor button  105 , R concentrate timing motor button  106 , or T concentrate timing motor button  107  to obtain the desired drink.  
         [0028]      FIG. 3A  is a diagram showing a lift mechanism at the outlets of liquid concentrate and diluting water in an automatic liquid metering apparatus according to the invention.  
         [0029]     The lift mechanism is disposed with a small cup positioning switch  127 , a medium cup positioning switch  128 , and a large pot positioning switch  129  which corresponds respectively to the height of small cup, medium cup and large pot. The control point is set at the liquid jacket assembly  131  stop point  130  where motor running stops when it moves to the stop point as dictated by the choice of small cup, medium cup and large pot buttons on the microprocessor control panel. The liquid jacket assembly  131  is disposed with three concentrate outlets, a diluting water outlet and a heat insulation pad  132 . The heat insulation pad  132  is installed to block heat transfer from diluting water which is hot water to the three concentrate sets so as to retain their original flavor. The liquid jacket assembly  131  is secured to the liquid jacket assembly connecting shaft  137 . The connecting shaft  137  is the assembly of a lift balancing shaft  135  and mounting mechanism  125  and secured to the lift assembly holder  139 . On the rack of liquid jacket assembly connecting shaft  137 , there is a gear sleeve  136  with helical gear shaft  134  disposed in the middle. The helical gear shaft  134  is linked to and rotates with the axis of lifting gear motor  138  seated on motor stand  124  of lift assembly holder  139 . The lift assembly holder  139  is provided with a slide space  126  that makes the vertical movement of the axis of lifting gear motor  138  coupled with the liquid jacket assembly  131  easier. The liquid jacket assembly connecting shaft  137  is also provided with a slide space  126  that makes the vertical movement of lifting gear motor  138  coupled with the liquid jacket assembly  131  easier. In the aforesaid assembly structure, the liquid jacket assembly  131  will not be displaced by weight with the use of helical gears. Thus this lift mechanism has a stable design. The movement of the lift mechanism is also microprocessor controlled as shown in  FIG. 4 . Furthermore, the lifting distance of the lift mechanism is adjustable according to user&#39;s requirement.  
         [0030]      FIG. 3B  is a diagram showing an electromagnetic actuated lift mechanism at the outlets of concentrate and diluting water in an automatic liquid metering apparatus according to the invention.  
         [0031]     The lift mechanism is actuated by the electromagnetic actuator  166 . The electromagnetic actuator  166  actuates the electromagnetic actuator shaft  167  to move in and out so as to control the liquid jacket assembly  131  to move between some predetermined lifting positioning points. The electromagnetic actuator  166  is fixed on the fixing seat  169  for lifting swinging arm. The outer surface of the electromagnetic actuator shaft  167  is furnished with the spring  177 , and the electromagnetic actuator shaft  167  is fixed to one end of the lifting swinging arm  172  by means of the fixing shaft  176  in such a manner that the lifting swinging arm  172  is swingable about the fixing bolt  168  when the electromagnetic actuator  166  actuates the electromagnetic actuator shaft  167  to move in and out. The lifting swinging arm  172  is fixed to the fixing bolt  168  of the fixing seat  169  for lifting swinging arm. The liquid jacket assembly  131  is furnished with the lifting positioning axle  171 . The sliding gap  170  is formed between the lifting swinging arm  172  and the lifting positioning axle  171  adjacent to the liquid jacket assembly  131  because the displacement will occur when the liquid jacket assembly  131  is lifting up and down. The fixing seat  169  of lifting swinging arm  172  is fixed to the lift assembly holder  139  of the liquid jacket assembly  131 . By means of the aforesaid mechanism, when someone wants to get concentrate beverage such as concentrated coffee from the automatic liquid metering apparatus of the present invention, the user can push the button to start the microprocessor program controlled circuit to control the liquid jacket assembly  131  to lift to a selected positioning point, such like the small cup positioning point  174  or the medium cup positioning point  175 . he electromagnetic actuator  166  is powered for actuating the lifting swinging arm  172  to move together with the outlet jacket assembly containing the concentrate liquid tubing and dilute water tubing to the selected positioning point. When the feeding of the concentrate liquid and the dilute water is completed, the lift mechanism is moved back to the initial position by cutting off the power of the electromagnetic actuator which is controlled by the microprocessor program controlled circuit. As a result, the precise supply of the concentrate liquid and dilute water can be achieved, and the requirement of users is fulfilled.  
         [0032]      FIG. 3C  is a diagram showing a manually operated lift mechanism at the outlets of concentrate and diluting water in an automatic liquid metering apparatus according to the invention.  
         [0033]     The lift mechanism is actuated by manually swinging the manually actuated arm  178  for lifting the liquid jacket assembly  131  to the selected positioning points. The manually actuated arm  178  is fixed to the mid point of lifting swinging arm of the fixing seat for lifting swinging arm  172 . The liquid jacket assembly  131  is furnished with the lifting positioning axle  170  for movably connecting to the manually actuated arm  178 . The sliding gap  170  is formed between the manually actuated arm  178  and the lifting positioning axle  171  adjacent to the liquid jacket assembly  131  because the displacement will occur when the liquid jacket assembly  131  is lifting up and down. The positioning of the manually actuated arm  178  is achieved by forming a small cup positioning point  174  and a medium cup positioning point  175  on the elastic plate  173 . The fixing seat  169  for lifting swinging arm  172  and the elastic plate  173  are fixed to the lift assembly holder  139 .  
         [0034]     By means of the aforesaid mechanism, when someone wants to get concentrate beverage (such as concentrated coffee) from the automatic liquid metering apparatus of the present invention, the user can push the button to start the microprocessor program controlled circuit, and, in the mean time, the user can swing the manually actuated arm  178  to move the liquid jacket assembly  131  together with the concentrate liquid tubing and dilute water tubing to a selected positioning point such as small cup or medium cup. Then, the microprocessor program controlled circuit will control to supply predetermined quantity of concentrate liquid and the dilute water according to the positioning point of the liquid jacket assembly  131 . As a result, the precise supply of the concentrate liquid and dilute water can be achieved, and the requirement of users is fulfilled.  
         [0035]      FIG. 4  is a sectional view of the microprocessor control process of the liquid metering apparatus according to the invention.  
         [0036]     As shown, the body  123  is configured with a microprocessor control panel  160 , a top cover  150 , and a diluting water tank lid  151  on its exterior. Inside the body  123 , there are arranged with a diluting water tank  143 , a concentrate container  153 , and a lift mechanism to provide an integral, microprocessor-controlled process, and a small cup seat  140 , a medium cup seat  141 , and large cup seat  142 . To make a drink from the concentrate, connect the adaptor  154  at the lower part of concentrate container  153  to the liquid tubing  144 , which is connected to the inlet of D, R, T concentrate pump  161 ,  162 ,  163 . If a small cup of drink is desired, put the small cup over its seat  140  on the housing base  155 , press the small cup button on the microprocessor control panel  160 , then select the type of concentrate desired by pressing any of the concentrate motor buttons and indicate the preference of light or strong drink by pressing the light or strong button. Next, press the start button. At this time, the lifting gear motor  138  of the lift mechanism starts to run under microprocessor control, upon which, the liquid jacket assembly connecting shaft  137  and the liquid jacket assembly  131  begin the move down until reaching the liquid jacket assembly stop point  130  and contacting the small cup positioning switch  127  when the lifting gear motor  138  stops running. Then the microprocessor will drive the D, R, or T concentrate pump  161 ,  162 ,  163  as dictated by the type of concentrate selected. The concentrate pump will send the desired concentrate to the concentrate outlet  122  via the liquid tubing  144  and concentrate check valve  145  and discharge the metered amount set before the pump stops running. The microprocessor will also drive the diluting water pump or solenoid valve  147  to discharge metered amount of hot water into the cup via the diluting water check valve  146  and diluting water tubing  133 . The microprocessor then drives the lifting gear motor  138  of lift mechanism to rotate reversely and the lift mechanism will ascend until the lifting gear motor  138  contacts with the large pot positioning switch  129 . As this time, the drink made from concentrate may be removed from the apparatus. Because of the lift mechanism at the liquid outlet, liquid discharged into the cup will not spurt out. Also, in light of the poor fluidity of concentrate, the concentrate pump is designed with a larger diameter inlet  148  and a smaller diameter outlet  149  so sufficient amount of concentrate is drawn in and a metered amount of concentrate is dispensed. Also a recess may be provided on the housing base for the seating of small cup  140 , medium cup  141  and large pot  142  respectively to make it easier for user to know where to place the cup.  
         [0037]     With the arrangement of a diluting water tank heater  121  in the diluting water tank  143 , the diluting water may be cold water or hot water as set by the microprocessor program. The temperature of diluting water may be detected and displayed by a temperature sensor.  
         [0038]     If the microprocessor did not receive the instruction from medium cup button  110 , the liquid jacket assembly stop point  130  in the lift mechanism will not act when it is in contact with (passes) the medium cup positioning switch  128 .  
         [0039]     The lifting gear motor  138 , liquid jacket assembly connecting shaft  137 , small cup positioning switch  127 , medium cup positioning switch  128 , and large pot positioning switch  129  are all secured to the lift assembly holder  139 . The lift assembly holder  139  is secured to the body  123  on a platform beneath the microprocessor control panel  160 .  
         [0040]     Moreover, the present invention can also apply the following lifting method as an option. That is, the liquid jacket assembly connecting shaft  137  and the liquid jacket assembly  131  are firstly moved downward to the stop point  130  so as to contact the small cup positioning switch  127 . The lifting gear motor  138  of the lift mechanism can be set up by means of time delay to move a bit more lower after the small cup positioning switch  127  is pushed, such that the concentrate outlet  122  will be located inside the cup before the lifting gear motor  138  is actually stopped. When the feeding of concentrate liquid (e.g., concentrate beverage) is complete, the liquid jacket assembly  131  will then move up to the top end of the cup for feeding dilute water. As a result, the dilute water supplied by the diluting water motor pump will not spill nor contact the liquid jacket assembly  131  and the concentrate outlet  122 , which is also a characteristic of the present invention.  
         [0041]      FIG. 5A  and  FIG. 5B  show the manner of refilling the concentrate bag of a liquid metering apparatus according to the invention and the trigger of alarm when the bag becomes empty.  
         [0042]     As shown, the concentrate bag is placed in a concentrate container  153  disposed with a concentrate level alarm switch  165  at its bottom. The concentrate bag is made of soft material, such as aluminum foil or non-toxic plastic or rubber. An adaptor  154  is provided at the lower part of concentrate bag and an eyelet is provided in the upper part of the bag to provide an attachment point for the spring hook  159 . A concentrate refill inlet  158  with a cap  157  is disposed at the top of concentrate container. When the concentrate bag is full (as shown in  FIG. 5A ) and fills the concentrate container  153 , the spring hook  159  is pulled down by the weight of concentrate and the bag presses down on the concentrate level alarm switch  165 . As the concentrate is being depleted, the spring hook  159  lifts the concentrate bag away from the concentrate level alarm switch  165  (as shown in  FIG. 5B ), which will send out an alarm. Apparatus operator only needs to removes the cap  157  over the concentrate inlet  158  to refill the emptying concentrate bag.  
         [0043]     To replace the empty concentrate bag instead of refill, operator can press the front lid fastener  164  of body  123  to access the concentrate container  153  and remove the empty bag by detaching it from the adaptor  154 .  
         [0044]      FIG. 6  is a diagram showing the pressing mechanism squeezing the tubing of liquid concentrate according to the automatic liquid metering apparatus of the invention.  
         [0045]     The automatic liquid metering apparatus of the present invention is further furnished with a motor  180  of pressing mechanism which is fixed to the right bracket  183  of pressing mechanism by the screw  190 . The right bracket  183  is fixed to the base  182  by the screw  191 . The pressing mechanism  183  is fixed to the axle  181 . One end of the axle  181  is connected to the motor  180 , while the other end is pivoted on the left bracket  186  which is fixed to the base  182  by the screw  192 . The stopping switch  185  of motor is furnished on the left bracket  186 . The silicon tubing of liquid concentrate is located between the pressing mechanism  184  and the base  182 . The operating process of the pressing mechanism  184  is schematically illustrated by means of numerals  187 ,  188  and  189  shown in  FIG. 6 . For example, when the concentrate pump stops pumping, there will be some liquid concentrate remaining at the outlet of tubing and forming a semi-sphere shaped drop  187  there. After some time later, say ten minutes or more, the semi-sphere shaped drop  187  of liquid concentrate will start drying out from its appearance due to air flow and temperature. As a result, liquid concentrate will tend to spray toward everywhere when next time the concentrate pump is working again. Therefore, the present invention discloses the motor  180  of pressing mechanism that will automatically operate to rotate the pressing mechanism  184  after the concentrate pump stops pumping. When the motor  180  rotates the pressing mechanism  184 , the pressing mechanism  184  compresses part of the tubing to squeeze some liquid concentrate out of the outlet so as to form the drops  188 . And, after a full turn of rotation, the pressing mechanism  184  contacts the stopping switch  185  and causes the motor  180  to stop rotation, and then the tubing returns back to its original circular shape due to its own resilience so as to suck the liquid concentrate  189  located at the outlet back to the interior of tubing. As a result, there will be no more semi-sphere shaped drop remaining at the outlet of tubing. The outlet will become a plane and thus the remaining liquid concentrate  189  inside the tubing will not be easily influenced by the drying effect due to air flow or temperature. Therefore, the liquid concentrate will flow smoothly and vertically toward the cup every time when the concentrate pump operates again.  
         [0046]     While the present invention has been shown and described with reference to the preferred embodiments thereof and in terms of the illustrative drawings, it should not be considered as limited thereby. Various possible modifications and alterations could be conceived of by one skilled in the art to the form and the content of any particular embodiment, without departing from the scope and the spirit of the present invention.