Abstract:
A refrigerator having a carbonated water production device, according to one concept of the present invention, comprises: a pressure regulator for adjusting and emitting the pressure of carbon dioxide emitted from a carbon dioxide cylinder; a solenoid switch valve for controlling the supply of the carbon dioxide discharged from the pressure regulator to a carbonated water tank; a connection channel for connecting the pressure regulator and the solenoid switch valve; and a relief valve arranged in the connection channel so as to discharge the carbon dioxide of the connection channel to the atmosphere if the pressure of the carbon dioxide of the connection channel is greater than a predetermined pressure limit. Thus, the pressure of the carbon dioxide of the connection channel is capable of being maintained at a predetermined pressure limit or less, and solenoid malfunction can be prevented so as to improve reliability and stability of a system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. national stage application of International Application No. PCT/KR2014/007924 filed Aug. 26, 2014, and claims the benefit of Korean Application No. 10-2013-0106868, filed Sep. 5, 2013, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The present invention relates to a refrigerator having a carbonated water generating module. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, refrigerators are devices which include storage chambers which store food and cold air supply units which supply cold air to the storage chambers, and thus maintain the freshness of the stored food. The refrigerators may include ice-making devices which make ice, and dispensers from which users extract water or the ice from the outside without opening doors to meet the requirement of the users, and furthermore, may also include carbonated water production devices which generate carbonated water. 
         [0006]    The carbonated water production device includes a carbon dioxide cylinder in which a high pressure carbon dioxide gas is stored, and a carbonated water tank in which carbonated water is produced by mixing carbon dioxide and water. 
         [0007]    In addition, the carbonated water production device includes a pressure regulator which adjusts a pressure of the carbon dioxide discharged from the carbon dioxide cylinder, and a solenoid switch valve which regulates supplying of the carbon dioxide discharged from the pressure regulator to the carbonated water tank. 
         [0008]    When the carbon dioxide charged in the carbon dioxide cylinder is discharged, the pressure regulator adjusts the pressure thereof to about 8.5 bar for discharging the carbon dioxide. This is a suitable pressure for mixing the carbon dioxide and water in the carbonated water tank. When a connection channel between the pressure regulator and the solenoid switch valve is congested with the carbon dioxide discharged from the pressure regulator, the carbon dioxide may be heated by external heat and a pressure thereof can increase. When the pressure of the carbon dioxide increases as described above, there is a problem in that the solenoid switch valve cannot be opened. 
         [0009]    In addition, since the carbon dioxide cylinder is a consumable component, when the carbon dioxide is all exhausted, the carbon dioxide cylinder should be replaced. 
       SUMMARY 
     Technical Problem 
       [0010]    The present invention is directed to providing a refrigerator including a carbonated water production device which prevents a malfunction of a solenoid switch valve among a pressure regulator which adjusts a pressure of carbon dioxide charged in a carbon dioxide cylinder and discharges the carbon dioxide, and the solenoid switch valve which regulates supplying of the carbon dioxide discharged from the pressure regulator to a carbonated water tank even when the pressure of the carbon dioxide increases, and has a system having improved reliability and safety. 
         [0011]    In addition, the present invention is also directed to providing a refrigerator including a notifier which senses when carbon dioxide charged in a carbon dioxide cylinder is consumed and when a replacement of the carbon dioxide cylinder is needed, and displays the replacement of the carbon dioxide cylinder to the outside. 
       Technical Solution 
       [0012]    One aspect of the present invention provides a refrigerator including: a main body; a carbonated water tank in which carbon dioxide and water are mixed to produce carbonated water; a carbon dioxide cylinder in which carbon dioxide is charged; a pressure regulator which adjusts a pressure of carbon dioxide discharged from the carbon dioxide cylinder and discharges the carbon dioxide; a solenoid switch valve which regulates supplying of the carbon dioxide discharged from the pressure regulator to the carbonated water tank; a connection channel which connects the pressure regulator and the solenoid switch valve; and a relief valve which is provided in the connection channel to discharge carbon dioxide in the connection channel to the atmosphere when a pressure of the carbon dioxide in the connection channel is greater than a predetermined pressure limit. 
         [0013]    A pressure of carbon dioxide which flows into the solenoid switch valve may be maintained equal to or less than the predetermined pressure limit by operating the relief valve, and a malfunction of the solenoid switch valve due to a high pressure may be prevented. 
         [0014]    The predetermined pressure limit may be determined to be in the range of 9.5 to 11.5 bar. 
         [0015]    The relief valve may include: a first relief valve body; a second relief valve body coupled to the first relief valve body; a relief main channel which is formed in the first relief valve body and having both ends each in communication with the connection channel; a relief discharge channel which is formed in the second relief valve body, has one end which communicates with the relief main channel, and the other end having an opening facing the outside; a relief switch member which moves forward or backward due to a pressure of carbon dioxide in the relief main channel and opens or closes the relief discharge channel; and a relief elastic member which elastically supports the relief switch member. 
         [0016]    When a pressure of carbon dioxide in the connection channel is greater than the predetermined pressure limit, the relief switch member may move in one direction and open the relief discharge channel, and when a pressure of the carbon dioxide in the connection channel is less than the predetermined pressure limit, the relief switch member may move in a direction opposite the one direction, and close the relief discharge channel. 
         [0017]    Another aspect of the present invention provides a refrigerator including: a main body; a storage chamber provided in the main body; a door which opens or closes the storage chamber; a carbonated water tank in which carbon dioxide and water are mixed to produce carbonated water; a carbon dioxide cylinder in which carbon dioxide is charged; a pressure regulator which adjusts a pressure of carbon dioxide discharged from the carbon dioxide cylinder and discharges the carbon dioxide; a solenoid switch valve which regulates supplying of the carbon dioxide discharged from the pressure regulator to the carbonated water tank; a connection channel which connects the pressure regulator and the solenoid switch valve; a notifier which notifies of a replacement time of the carbon dioxide cylinder; a low pressure sensor integrated relief valve which sends a low pressure signal when a pressure of carbon dioxide in the connection channel is less than a predetermined replacement pressure, and discharges the carbon dioxide in the connection channel when a pressure of the carbon dioxide in the connection channel is greater than a predetermined pressure limit; and a controller which receives the low pressure signal sent from the low pressure sensor integrated relief valve, and controls the notifier to notify of a replacement time of the carbon dioxide cylinder. 
         [0018]    The notifier may include a display unit provided on the door. 
         [0019]    A pressure of carbon dioxide which flows into the solenoid switch valve may be maintained equal to or less than the predetermined pressure limit by operating the low pressure sensor integrated relief valve, and a malfunction of the solenoid switch valve due to a high pressure may be prevented. 
         [0020]    The predetermined replacement pressure may be determined to be in the range of 7.3 to 7.7 bar. 
         [0021]    The predetermined pressure limit may be determined to be in the range of 9.5 to 11.5 bar. 
         [0022]    The low pressure sensor integrated relief valve m installed at an inlet of the solenoid switch valve. 
         [0023]    The low pressure sensor integrated relief valve may include: a valve body; a valve main channel which is formed in the valve body and has both ends in communication with the connection channel; a diaphragm installed in the valve body; a partition space partitioned from the valve main channel by the diaphragm; a pusher which moves forward or backward due to a pressure of carbon dioxide in the valve main channel; a micro switch which is pressed by the pusher and is turned on or off; and a pusher elastic member which elastically supports the pusher. 
         [0024]    When a pressure of carbon dioxide in the connection channel is less than the replacement pressure, the pusher may move in one direction, be separated from the micro switch, and turn on the micro switch, and when a pressure of the carbon dioxide in the connection channel is greater than the replacement pressure, the pusher may move in a direction opposite the one direction, press the micro switch, and turn off the micro switch. 
         [0025]    When the micro switch is turned on, the micro switch may send a low pressure signal to the controller. 
         [0026]    The low pressure sensor integrated relief valve may include: a valve body; a valve main channel which is formed in the valve body and has both ends in communication with the connection channel; a valve discharge channel which is formed in the valve body, has one end in communication with the valve main channel, and the other end having an opening facing the outside; a valve switch member which moves forward or backward due to a pressure of carbon dioxide in the valve main channel and opens or closes the valve discharge channel; and a valve elastic member which elastically supports the valve switch member. 
         [0027]    When a pressure of carbon dioxide in the connection channel is greater than the predetermined pressure limit, the valve switch member may move in one direction and open the valve discharge channel, and when a pressure of the carbon dioxide in the connection channel is less than the predetermined pressure limit, the switching member may move in another direction and close the valve discharge channel. 
         [0028]    Still another aspect of the present invention provides a method of controlling a refrigerator which includes a carbonated water tank in which carbon dioxide and water are mixed to produce carbonated water, a carbon dioxide cylinder in which carbon dioxide is charged, a pressure regulator which adjusts a pressure of carbon dioxide discharged from the carbon dioxide cylinder and discharges the carbon dioxide, a solenoid switch valve which regulates supplying of the carbon dioxide discharged from the pressure regulator to the carbonated water tank, a connection channel which connects the pressure regulator and the solenoid switch valve, a notifier which notifies of a replacement time of the carbon dioxide cylinder, and a low pressure sensor integrated relief valve provided in the connection channel, the method including: sensing a pressure of carbon dioxide in the connection channel by the low pressure sensor integrated relief valve; displaying a replacement time by the notifier when the sensed pressure is less than a predetermined replacement pressure; and discharging the carbon dioxide in the connection channel to the atmosphere by the low pressure sensor integrated relief valve when the sensed pressure is greater than a predetermined pressure limit. 
       Advantageous Effects 
       [0029]    According to exemplary embodiments of the present invention, a relief valve disposed between a pressure regulator and a carbon dioxide switching valve reduces a pressure of carbon dioxide by discharging the carbon dioxide to the atmosphere between the pressure regulator which adjusts the pressure of the carbon dioxide discharged from a carbon dioxide cylinder and discharges the carbon dioxide and a solenoid switch valve which regulates supplying of the carbon dioxide to a carbonated water tank, thereby the relief valve can prevent a malfunction of a solenoid switch valve due to a high pressure. Accordingly, the reliability and safety of the carbonated water making system can be improved. 
         [0030]    A low pressure sensor which senses a low pressure of carbon dioxide is provided in the relief valve, when carbon dioxide has a pressure equal to or less than a predetermined replacement pressure, the low pressure sensor transmits a signal to a notifier, and thus the notifier can easily recognize that the replacement time of the carbon dioxide cylinder is close. 
         [0031]    Since the relief valve and the low pressure sensor are integrally formed, components are simplified and the space utilization can be improved when compared to a case in which the relief valve and the low pressure sensor are provided separately. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1  is a perspective view illustrating an exterior of a refrigerator according to one embodiment of the present invention. 
           [0033]      FIG. 2  is a perspective view illustrating an inside of the refrigerator of  FIG. 1 . 
           [0034]      FIG. 3  is an exploded perspective view illustrating an assembly structure of a carbonated water generating module of the refrigerator of  FIG. 1 . 
           [0035]      FIG. 4  is a perspective view when a cover of the carbonated water generating module of the refrigerator of  FIG. 1  is separated therefrom. 
           [0036]      FIG. 5  is an exploded perspective view illustrating a pressure regulator of the refrigerator of  FIG. 1  and a peripheral structure thereof. 
           [0037]      FIG. 6  is a cross-sectional view illustrating the pressure regulator of the refrigerator of  FIG. 1  and the peripheral structure thereof. 
           [0038]      FIG. 7  is a perspective view illustrating a relief valve of the refrigerator of  FIG. 1  and a peripheral structure thereof. 
           [0039]      FIG. 8  is a cross-sectional view illustrating a structure of the relief valve of the refrigerator of  FIG. 1  when the relief valve is closed. 
           [0040]      FIG. 9  is a cross-sectional view illustrating a structure of the relief valve of the refrigerator of  FIG. 1  when the relief valve is open. 
           [0041]      FIG. 10  is a circuit diagram for describing a process of generating and discharging carbonated water in the refrigerator of  FIG. 1 . 
           [0042]      FIG. 11  is a perspective view illustrating a low pressure sensor integrated relief valve of a refrigerator according to another embodiment of the present invention and a peripheral structure thereof. 
           [0043]      FIG. 12  is a view illustrating a coupling relationship of the low pressure sensor integrated relief valve of the refrigerator of  FIG. 11 . 
           [0044]      FIG. 13  is an exploded perspective view illustrating a structure of the low pressure sensor integrated relief valve of the refrigerator of  FIG. 11 . 
           [0045]      FIG. 14  is a cross-sectional view illustrating the low pressure sensor integrated relief valve of the refrigerator of  FIG. 11  when a valve discharge channel is closed and a micro switch is turned off. 
           [0046]      FIG. 15  is a cross-sectional view illustrating the low pressure sensor integrated relief valve of the refrigerator of  FIG. 11  when the valve discharge channel is open and the micro switch is turned off. 
           [0047]      FIG. 16  is a cross-sectional view illustrating the low pressure sensor integrated relief valve of the refrigerator of  FIG. 11  when the valve discharge channel is closed and the micro switch is turned on. 
           [0048]      FIG. 17  is a circuit diagram for describing a process of generating and discharging carbonated water in the refrigerator of  FIG. 11 . 
           [0049]      FIG. 18  is a view illustrating a replacement notifier of a carbon dioxide cylinder of the refrigerator of  FIG. 11 . 
           [0050]      FIG. 19  is a control block diagram of the refrigerator of  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION 
       [0051]    Hereinafter, exemplary embodiments of the present invention will be described in detail. 
         [0052]      FIG. 1  is a perspective view illustrating an exterior of a refrigerator according to one embodiment of the present invention, and  FIG. 2  is a perspective view illustrating an inside of the refrigerator of  FIG. 1 . 
         [0053]    Referring to  FIGS. 1 and 2 , the refrigerator  1  according to one embodiment of the present invention may include a main body  10 , storage chambers  20  and  30  formed in the main body  10 , and a cold air supply unit (not shown) which supplies cold air to the storage chambers  20  and  30 . 
         [0054]    The main body  10  may include inner boxes forming the storage chambers  20  and  30 , an outer box which is coupled to outer sides of the inner boxes and forms an exterior of the refrigerator, and an insulation material which is disposed between the inner boxes and the outer box and insulates the storage chambers  20  and  30 . 
         [0055]    The storage chambers  20  and  30  may be partitioned into a refrigerator compartment  20  positioned at an upper portion and a freezer compartment  30  positioned at a lower portion by an intermediate partition  11 . Shelves  23  on which food may be placed, and at least one storage box  27  which keeps food in a sealed state may be provided in the refrigerator compartment  20 . 
         [0056]    In addition, an ice-making chamber  81  capable of generating ice may be formed at an upper corner of the refrigerator compartment  20 . The ice-making chamber  81  may be insulated and partitioned from the refrigerator compartment  20  by an ice-making chamber case  82 . An ice-making device  80  such as an ice-making tray and an ice bucket which stores the ice generated in the ice-making tray may be provided in the ice-making chamber  81 . 
         [0057]    Meanwhile, a water tank  70  capable of storing water may be provided in the refrigerator compartment  20 . As illustrated in  FIG. 2 , the water tank  70  may be provided between a plurality of storage boxes  27 , but is not limited thereto. The water tank  70  may be provided in the refrigerator compartment  20  so that water in the water tank  70  is cooled due to cold air in the refrigerator compartment  20 . 
         [0058]    The water tank  70  may be connected to an external water source  40  (see  FIG. 10 ) such as tap water, and may store water purified by a water purifying filter  50  (see  FIG. 10 ). A channel switching valve  60  may be provided in a water supply pipe which connects the external water source  40  and the water tank  70 , the channel switching valve  60  may selectively supply water supplied by the external water source  40  to the water tank  70  or the ice-making device  80 . 
         [0059]    Each of the refrigerator compartment  20  and the freezer compartment  30  has an open front through which food is introduced or withdrawn, the open front of the refrigerator compartment  20  may be opened or closed by a pair of rotational doors  21  and  22  hinge-coupled to the main body  10 , and the open front of the freezer compartment  30  may be opened or closed by a sliding door  31  which is movable by sliding with respect to the main body  10 . A door guard  24  which may store food may be provided on the rear surface of the refrigerator compartment doors  21  and  22 . 
         [0060]    Meanwhile, gaskets  28  which seal between the refrigerator compartment doors  21  and  22  and the main body  10  to keep cold air of the refrigerator compartment  20  when the refrigerator compartment doors  21  and  22  are closed may be provided at edges of the rear surfaces of the refrigerator compartment doors  21  and  22 . In addition, a rotational bar  26  which seals between the refrigerator compartment door  21  and the refrigerator compartment door  22  to keep the cold air of the refrigerator compartment  20  when the refrigerator compartment doors  21  and  22  are closed may be provided at any one refrigerator compartment door of the refrigerator compartment doors  21  and  22 . 
         [0061]    In addition, a dispenser  90  which may extract water or ice from the outside without opening the refrigerator compartment door  21  may be provided in any one refrigerator compartment door of the refrigerator compartment doors  21  and  22 . 
         [0062]    The dispenser  90  may include a water-intake space  91  into which a container, such as a cup, is inserted and through which water or ice may be withdrawn, a control panel  92  in which input buttons through which various settings of the dispenser  90  are input and a display which displays various types of information of the dispenser  90  are provided, and an operation lever  93  which may operate the dispenser  90  to discharge water or ice. 
         [0063]    In addition, the dispenser  90  may include an ice guide channel  94  which connects the ice-making device  80  and the water-intake space  91  to discharge ice generated by the ice-making device  80  to the water-intake space  91 . 
         [0064]    Meanwhile, a carbonated water generating module  100  which generates carbonated water may be installed at a rear surface of the refrigerator compartment door  21  in which the dispenser  90  of the refrigerator  1  according to one embodiment of the present invention is provided. The carbonated water generating module  100  will be described in detail below. 
         [0065]      FIG. 3  is an exploded perspective view illustrating an assembly structure of a carbonated water generating module of the refrigerator of  FIG. 1 ,  FIG. 4  is a perspective view when a cover of the carbonated water generating module of the refrigerator of  FIG. 1  is separated therefrom,  FIG. 5  is an exploded perspective view illustrating a pressure regulator of the refrigerator of  FIG. 1  and a peripheral structure thereof,  FIG. 6  is a cross-sectional view illustrating the pressure regulator of the refrigerator of  FIG. 1  and the peripheral structure thereof,  FIG. 7  is a perspective view illustrating a relief valve of the refrigerator of  FIG. 1  and a peripheral structure thereof,  FIG. 8  is a cross-sectional view illustrating a structure of the relief valve of the refrigerator of  FIG. 1  when the relief valve is closed,  FIG. 9  is a cross-sectional view illustrating a structure of the relief valve of the refrigerator of  FIG. 1  when the relief valve is open, and  FIG. 10  is a circuit diagram for describing a process of generating and discharging carbonated water in the refrigerator of  FIG. 1 . 
         [0066]    Referring to  FIGS. 3 to 10 , the carbonated water generating module  100  for generating carbonated water in the refrigerator  1  may include a carbon dioxide cylinder  120  in which high pressure carbon dioxide is charged, a carbonated water tank  110  in which water and carbon dioxide are mixed to produce carbonated water, a module case  140  which has accommodation spaces  151 ,  152 , and  153  which accommodate the carbon dioxide cylinder  120  and the carbonated water tank  110  and is coupled to the rear surface of the refrigerator compartment door  21 , and an integrated valve assembly  130 . 
         [0067]    The high pressure carbon dioxide in the range of about 45 to 60 bar may be charged in the carbon dioxide cylinder  120 . The carbon dioxide cylinder  120  may be installed in a cylinder connector  157  of the module case  140 , and may be accommodated in a lower accommodation space  153  of the module case  140 . 
         [0068]    A carbon dioxide gas in the carbon dioxide cylinder  120  may be supplied to the carbonated water tank  110  through a carbon dioxide supply channel  200  which connects the carbon dioxide cylinder  120  and the carbonated water tank  110 . 
         [0069]    A pressure regulator  201  which adjusts a pressure of a carbon dioxide gas, a solenoid switch valve  202  which opens or closes the carbon dioxide supply channel  200 , and a carbon dioxide gas backflow prevention valve  203  which prevents backflow of a carbon dioxide gas may be provided in the carbon dioxide supply channel  200 . 
         [0070]    The pressure regulator  201  may decrease a pressure of a carbon dioxide gas discharged from the carbon dioxide cylinder  120  to about 8.5 bar to discharge the carbon dioxide gas. 
         [0071]    Carbonated water is generated by mixing carbon dioxide supplied by the carbon dioxide cylinder  120  and purified water supplied by the water tank  70  in the carbonated water tank  110  which may store the generated carbonated water. 
         [0072]    The carbonated water tank  110  may be connected with a water supply channel  210  to which water is supplied from the water tank  70 , a carbonated water discharge channel  230  which discharges the generated carbonated water to the water-intake space  91 , an exhaust channel  250  which discharges residual carbon dioxide gas in the carbonated water tank  110  before supplying water to the carbonated water tank  110 , as well as the above-described carbon dioxide supply channel  200 . 
         [0073]    A water supply solenoid valve  211  which opens or closes a water supply channel  210  may be provided in the water supply channel  210 . A carbonated water discharge solenoid valve  231  which opens or closes the carbonated water discharge channel  230 , and a carbonated water regulator  232  which adjusts a pressure of discharged carbonated water may be provided in the carbonated water discharge channel  230 . An exhaust valve  251  which opens or closes the exhaust channel  250  may be provided in the exhaust channel  250 . 
         [0074]    Meanwhile, a water level sensor  111  capable of measuring an amount of water supplied to the carbonated water tank  110 , and a temperature sensor  112  capable of measuring a temperature of water supplied to the carbonated water tank  110  or a temperature of carbonated water generated by the carbonated water tank  110  may be provided in the carbonated water tank  110 . 
         [0075]    In addition, a tank safety valve  114 , which may discharge a high pressure carbon dioxide gas when the high pressure carbon dioxide gas having a pressure more than a predetermined pressure is supplied to the carbonated water tank  110  due to a malfunction of the pressure regulator  201  and the like, may be provided in the carbonated water tank  110 . 
         [0076]    The above-described carbonated water tank  110  may be formed to have a predetermined size, and may be formed to accommodate about 1 l of purified water. In addition, the carbonated water tank  110  may be formed of a stainless material to minimize a space occupied thereby, withstand high pressure, and have corrosion resistance. The carbonated water tank  110  may be accommodated in a first upper accommodation space  151  of the module case  140 . The carbonated water tank  110  may be supported by a bottom support portion  155  of the module case  140  and a guide portion  156 . 
         [0077]    Meanwhile, the integrated valve assembly  130  may be formed with the above-described water supply solenoid valve  211 , the carbonated water discharge solenoid valve  231 , and a water discharge solenoid valve  221 . 
         [0078]    That is, the water supply solenoid valve  211 , the carbonated water discharge solenoid valve  231 , and the water discharge solenoid valve  221  may be integrally formed as one unit. The above-described integrated valve assembly  130  may be accommodated in a second upper accommodation space  152  of the module case  140 . 
         [0079]    The module case  140  may include a back case  150  having one open side, and a cover  160  coupled to the one open side of the back case  150 . 
         [0080]    At least one insertion groove  154  may be formed at a position corresponding to at least one insertion protrusion  25  formed on the rear surface of the refrigerator compartment door  21 , in the module case  140 . Accordingly, as the insertion protrusion  25  is inserted into the insertion groove  154 , the module case  140  may be easily installed on the rear surface of the refrigerator compartment door  21 . However, the above-described coupling structure is only an example, and the module case  140  may be detachably installed on the rear surface of the refrigerator compartment door  21  using various coupling structures, such as a screw coupling structure and a hook coupling structure, as well as the above-described insertion structure. 
         [0081]    In addition, an insertion groove  158  and an insertion protrusion  162  may be formed at positions respectively corresponding to each other in the back case  150  and the cover  160  such that the cover  160  is coupled to the back case  150 . However, the above-described coupling structure is also an example, and the back case  150  and the cover  160  may be detachably coupled to each other using various coupling structures. 
         [0082]    Meanwhile, when the cover  160  is coupled to the back case  150 , the carbon dioxide cylinder  120  in the module case  140 , the carbonated water tank  110 , and the integrated valve assembly  130  may not be exposed to the outside. Accordingly, the aesthetic value of the refrigerator compartment door  21  may not be decreased. 
         [0083]    However, since a ventilation opening  161  through which an inside of the module case  140  is communicated with the outside is formed in the cover  160 , even when the cover  160  is coupled to the back case  150 , cold air in the storage chamber is supplied to the carbonated water tank  110  in the module case  140 , and carbonated water stored in the carbonated water tank  110  may be cooled or maintained at an optimum temperature. 
         [0084]    An installation structure of the carbon dioxide cylinder  120  and an operation of the pressure regulator  201  will be described with reference to  FIGS. 5 to 7 . 
         [0085]    The refrigerator further includes a safety unit  750  which couples the carbon dioxide cylinder  120  coupled to the cylinder connector  157  to the pressure regulator  201 . The safety unit  750  includes a safety lever  752  which is pivotably provided at a side of the cylinder connector  157  coupled to one side of the carbon dioxide cylinder  120  and selectively moves the carbon dioxide cylinder  120  toward or away from the pressure regulator  201  according to rotation. 
         [0086]    The cylinder connector  157  includes a cylinder connector main body  157   a  having a cylindrical shape, a cylinder connector hole  157   b  into which an suction nozzle  201   a  of the pressure regulator  201  is inserted, a cylinder connector movable shaft  157   c  formed to protrude from the cylinder connector main body  157   a,  and a cylinder coupling portion  157   d  to which a spray nozzle of the carbon dioxide cylinder  120  is screw coupled. 
         [0087]    Even after the carbon dioxide cylinder  120  is coupled to the cylinder connector  157 , the suction nozzle  201   a  of the pressure regulator  201  and the spray nozzle of the carbon dioxide cylinder  120  are provided to be separated by a predetermined distance. This is for preventing the suction nozzle  201   a  of the pressure regulator  201  and the spray nozzle of the carbon dioxide cylinder  120  from coupling together without an operation of the safety unit  750  even when the carbon dioxide cylinder  120  is coupled to the cylinder connector  157 . 
         [0088]    The safety lever  752  includes a lever portion  754  which receives a force, a lever side portion  756  including a lever rotational shaft portion  756   a  provided so that the safety lever  752  is pivotable, and a cylinder connector separation portion  758  which is provided at the lever side portion  756  and pushes away the cylinder connector movable shaft  157   c.    
         [0089]    As the lever portion  754  is provided to vertically move about the lever rotational shaft portion  756   a  provided in the lever side portion  756 , and the lever portion  754  is vertically moved, the cylinder connector  157  may be detached from the pressure regulator  201 . 
         [0090]    The lever side portion  756  is formed to be bent from the lever portion  754  toward both sides, and the lever side portion  756  includes the lever rotational shaft portion  756   a  provided so that the lever portion  754  is pivotable at a side of the pressure regulator  201 . 
         [0091]    The safety unit  750  includes a safety lever holder  760  for converting a rotary motion of the safety lever  752  into a forward or backward motion of the cylinder connector  157 . 
         [0092]    The safety lever holder  760  is a component provided at a rear surface of the pressure regulator  201 , and includes a holder coupling shaft  760   b  coupled to the safety lever  752 , and a cylinder connector seating groove  760   a  in which the cylinder connector movable shaft  157   c  is seated. 
         [0093]    A safety lever coupling shaft  756   b  is provided at the lever side portion  756  of the safety lever  752  to be coupled to the safety lever holder  760 . The safety lever coupling shaft  756   b  is provided to be separated from the lever rotational shaft portion  756   a.  As the holder coupling shaft  760   b  and the safety lever coupling shaft  756   b  of the safety lever holder  760  are coupled, the rotary motion of the safety lever  752  is transferred to the safety lever holder  760 . 
         [0094]    Specifically, when the lever portion  754  is moved upward about the lever rotational shaft portion  756   a,  the safety lever coupling shaft  756   b  and the holder coupling shaft  760   b  are moved upward, and thus the safety lever holder  760  is moved upward. When the lever portion  754  is moved downward, the safety lever coupling shaft  756   b  and the holder coupling shaft  760   b  are moved downward, and thus the safety lever holder  760  is moved downward. 
         [0095]    The cylinder connector seating groove  760   a  in which the cylinder connector movable shaft  157   c  is seated is provided to have a recessed shape in the safety lever holder  760 . The cylinder connector seating groove  760   a  is seated to support a lower portion of the cylinder connector movable shaft  157   c.  As the safety lever holder  760  is moved upward with the above-described structure, the cylinder connector movable shaft  157   c  is moved upward. 
         [0096]    The pressure regulator  201  includes a cylinder connector rail case  201   c  to surround the cylinder connector  157 . A cylinder connector rail  201   d  which guides a vertical movement of the cylinder connector movable shaft  157   c  is provided in a side of the cylinder connector rail case  201   c.    
         [0097]    A pressure regulator rotational shaft  711 , which protrudes from a side to have a shaft shape so that the pressure regulator  201  is pivotable, is provided in a side of the pressure regulator  201 . As an outer surface of the pressure regulator  201  is surrounded by a pressure regulator case  710 , an inner structure of the pressure regulator  201  may be protected from the external environment. 
         [0098]    A gas cylinder guide portion  780  which guides the carbon dioxide cylinder  120  having a cylindrical shape may be provided at one side of the carbon dioxide cylinder  120 . The gas cylinder guide portion  780  includes a cylinder close contacting guide portion  780   a  which guides at least one side of the carbon dioxide cylinder  120  in a lengthwise direction of the carbon dioxide cylinder  120  having the cylindrical shape while in close contact therewith, a cylinder separation guide portion  780   b  which is provided on the cylinder close contacting guide portion  780   a  and is separated from the carbon dioxide cylinder  120  by a predetermined distance, and a cylinder seating portion  780   c  on which a lower portion of the carbon dioxide cylinder  120  is seated. 
         [0099]    Meanwhile, as well illustrated in  FIG. 7 , a relief valve  800  is provided in a connection channel  200   a  which connects the pressure regulator  201  and the solenoid switch valve  202 , wherein the relief valve  800  decreases a pressure by discharging carbon dioxide in the connection channel  200   a  when the pressure of the carbon dioxide in the connection channel  200   a  is greater than a predetermined pressure limit. 
         [0100]    Here, the connection channel  200   a  refers to a part of the carbon dioxide supply channel  200  which connects the pressure regulator  201  and the carbonated water tank  110  to supply carbon dioxide to the carbonated water tank  110 , and refers to a section between the pressure regulator  201  and the solenoid switch valve  202  in the carbon dioxide supply channel  200 . 
         [0101]    The reason why the relief valve  800  is provided in the connection channel  200   a  is that the solenoid switch valve  202  does not operate normally when the connection channel  200   a  is congested with carbon dioxide and the carbon dioxide absorbs external heat to increase the temperature, and thus the pressure increases to a high pressure. 
         [0102]    Specifically, as described above, although the carbon dioxide compressed at a pressure of about 45 to 60 bar and charged in the carbon dioxide cylinder  120  is discharged at a pressure of about 8.5 bar or less through the pressure regulator  201 , according to an algorithm, when the solenoid switch valve  202  is closed, the connection channel  200   a  which connects the pressure regulator  201  and the solenoid switch valve  202  is congested with the carbon dioxide discharged from the pressure regulator  201 . At this time, as the temperature of the carbon dioxide increases due to external heat, the pressure may increase to a high pressure of 8.5 bar or more. 
         [0103]    Particularly, when the carbon dioxide cylinder  120  is excessively charged or a new carbon dioxide cylinder  120  is first installed, a pressure in the connection channel  200   a  may further increase. The reason is that, in the above-described case, as carbon dioxide flows fast in the pressure regulator  201 , a temperature thereof decreases sharply, and the carbon dioxide is discharged from the pressure regulator  201  in a state in which the carbon dioxide is not evaporated sufficiently. The carbon dioxide discharged in a liquid state may absorb heat in the connection channel  200   a,  be evaporated, and have a further high pressure. 
         [0104]    When a pressure of the solenoid switch valve  202  is about 15 bar or more, an opening operation is not performed easily according to an inner structure of the solenoid switch valve  202 , and thus, when the carbon dioxide in the connection channel  200   a  has a high pressure of 15 bar or more, the solenoid switch valve  202  may be not opened. 
         [0105]    The relief valve  800  may have a mechanical structure using an elastic force, and may be provided to discharge carbon dioxide to the atmosphere when the pressure of the carbon dioxide in the connection channel  200   a  reaches a predetermined pressure limit. Here, the predetermined pressure limit may be determined to be in the range of about 9.5 to 11.5 bar. 
         [0106]    Using the above-described structure, when a pressure of carbon dioxide in the connection channel  200   a  increases and reaches a pressure limit, the relief valve  800  discharges the carbon dioxide to the atmosphere and maintains the pressure of the carbon dioxide in the connection channel  200   a  at the pressure limit or less. Accordingly, a malfunction of the solenoid switch valve  202  due to a high pressure may not occur, and thus the reliability and safety of a carbonated water manufacturing system may be improved. 
         [0107]    The detail structure of the above-described relief valve  800  may be provided variously, and examples thereof may be provided as those illustrated in  FIGS. 8 and 9 . 
         [0108]    The relief valve  800  may include a first relief valve body  810 , a second relief valve body  820  coupled to the first relief valve body  810 , a relief main channel  811  formed in the first relief valve body  810  and having both ends in communication with the connection channel  200   a,  a relief discharge channel  821  formed in the second relief valve body  820  and having one end which communicates with the relief main channel  811  and the other end having an opening facing the outside, a relief switch member  830  which moves forward or backward due to a pressure of carbon dioxide in the relief main channel  811  to open or close the relief discharge channel  821 , and a relief elastic member  840  which elastically supports the relief switch member  830 . 
         [0109]    The relief valve  800  may also include an inlet  801  and an outlet  802  to which the connection channel  200   a  is connected, a packing member  831  provided in the relief switch member  830  to seal the relief discharge channel  821 , and an adjusting screw  850  for adjusting an elastic force of the relief elastic member  840 . 
         [0110]    As illustrated in  FIG. 9 , when a pressure in the connection channel  200   a  is transferred to the relief main channel  811  using the above-described structure, and the pressure of the relief main channel  811  is greater than a predetermined pressure limit, the relief switch member  830  may overcome the elastic force of the relief elastic member  840 , may move in one direction, and may open the relief discharge channel  821 . 
         [0111]    On the contrary, as illustrated in  FIG. 8 , when the pressure of the relief main channel  811  is less than the predetermined pressure limit, the relief switch member  830  may move in a direction opposite the one direction due to the elastic force of the relief elastic member  840 , and may close the relief discharge channel  821 . 
         [0112]      FIG. 11  is a perspective view illustrating a low pressure sensor integrated relief valve of a refrigerator according to another embodiment of the present invention and a peripheral structure thereof,  FIG. 12  is a view illustrating a coupling relationship of the low pressure sensor integrated relief valve of the refrigerator of  FIG. 11 ,  FIG. 13  is an exploded perspective view illustrating a structure of the low pressure sensor integrated relief valve of the refrigerator of  FIG. 11 ,  FIG. 14  is a cross-sectional view illustrating the low pressure sensor integrated relief valve of the refrigerator of  FIG. 11  when a valve discharge channel is closed and a micro switch is turned off,  FIG. 15  is a cross-sectional view illustrating the low pressure sensor integrated relief valve of the refrigerator of  FIG. 11  when the valve discharge channel is open and the micro switch is turned off,  FIG. 16  is a cross-sectional view illustrating the low pressure sensor integrated relief valve of the refrigerator of  FIG. 11  when the valve discharge channel is closed and the micro switch is turned on, and  FIG. 17  is a circuit diagram for describing a process of carbonated water generating and discharging of the refrigerator of  FIG. 11 . 
         [0113]    A carbonated water production device of the refrigerator according to another embodiment of the present invention will be described in detail with reference to  FIGS. 11 to 17 . The same reference number as that of one embodiment of the present invention refers to the same component in the drawings and a detail description thereof may be omitted. 
         [0114]    A refrigerator according to another embodiment of the present invention includes, instead of the relief valve of one embodiment, a low pressure sensor integrated relief valve  900 , a notifier  321  which notifies of a replacement time of a carbon dioxide cylinder, and a controller  310  which receives a low pressure signal sent from the low pressure sensor integrated relief valve  900  and controls the notifier  321 . 
         [0115]    The low pressure sensor integrated relief valve  900  integrates a low pressure sensor which senses a low pressure of carbon dioxide when the carbon dioxide is at a low pressure, and a relief valve which discharges carbon dioxide to the atmosphere when the carbon dioxide is at a high pressure, and is installed on a connection channel  200   a  which connects a pressure regulator  201  and a solenoid switch valve  202 . 
         [0116]    When a pressure of carbon dioxide in the connection channel  200   a  is less than a predetermined replacement pressure, the low pressure sensor integrated relief valve  900  generates a low pressure signal, and when the pressure of the carbon dioxide in the connection channel  200   a  is greater than the predetermined replacement pressure, the low pressure sensor integrated relief valve  900  discharges the carbon dioxide in the connection channel  200   a  to the atmosphere. 
         [0117]    As described above, the carbon dioxide cylinder  120  is charged at a pressure in the range of about 45 to 60 bar, and is consumable, a pressure of the carbon dioxide cylinder  120  decreases as carbon dioxide is consumed, and thus the carbon dioxide cylinder  120  has to be replaced when all of the carbon dioxide is consumed or the pressure thereof is not sufficient. 
         [0118]    However, when the replacement time of the carbon dioxide cylinder  120  is not properly notified of, a user may recognize whether all of the carbon dioxide of the carbon dioxide cylinder  120  is consumed or the pressure thereof is not sufficient through only sipping carbonated water and tasting it. 
         [0119]    To this end, the low pressure sensor integrated relief valve  900  senses first a pressure of carbon dioxide in the connection channel  200   a  and determines whether the pressure is low enough to need a replacement. 
         [0120]    That is, when the pressure of the carbon dioxide in the connection channel  200   a  is less than the predetermined replacement pressure, the low pressure sensor integrated relief valve  900  generates a low pressure signal. Here, the predetermined replacement pressure may be determined to be in the range of about 7.3 to 7.7 bar. 
         [0121]    As described above, since the pressure regulator  201  is provided to discharge carbon dioxide at a pressure of about 8.5 bar, when a pressure of carbon dioxide discharged from the pressure regulator  201  is in the range of 7.3 to 7.7 bar, a pressure of carbon dioxide of the carbon dioxide cylinder  120  has already reached a level in the range of 7.3 to 7.7 bar. 
         [0122]    The notifier  321  may include a display provided on a door. Specifically, the notifier  321  may include a light emitting diode (LED) and the like, and may emit light to visually display that the replacement time of the carbon dioxide cylinder  120  has arrived. 
         [0123]    When a pressure of carbon dioxide in the connection channel  200   a  is greater than a predetermined pressure limit, the low pressure sensor integrated relief valve  900  discharges the carbon dioxide in the connection channel  200   a  to the atmosphere and decreases the pressure of the carbon dioxide in the connection channel  200   a  similar to the relief valve of the above-described embodiment. Since an operation of discharging carbon dioxide is the same as that of the relief valve of the above-described embodiment, a detail description thereof will be omitted. 
         [0124]    Here, the predetermined pressure limit at which the low pressure sensor integrated relief valve  900  is open may be determined to be in the range of 9.5 to 11.5 bar, similar to the above-described embodiment. 
         [0125]    The detail structure of the low pressure sensor integrated relief valve  900  may be provided variously, and examples thereof may be provided as those illustrated in  FIGS. 12 to 16 . 
         [0126]    The low pressure sensor integrated relief valve  900  may include a valve body portion  910  which includes an upper case  910   a,  a middle case  910   b,  and a lower case  910   c,  a valve main channel  911  which is formed in the valve body portion  910  and has both ends in communication with the connection channel  200   a,  a diaphragm  920  installed in the valve body portion  910 , a partition space  912  partitioned from the valve main channel  911  by the diaphragm  920 , a pusher  930  which moves forward or backward due to a pressure of carbon dioxide in the valve main channel  911 , a micro switch  940  pressed by the pusher  930  to be turned on or off, a pusher elastic member  950  which elastically supports the pusher  930 , a valve discharge channel  913  formed in the valve body portion  910  and having one end in communication with the valve main channel  911  and the other end having an opening facing the outside, a valve switch member  960  which moves forward or backward due to a pressure of carbon dioxide in the valve main channel  911  to open or close the valve discharge channel  913 , and a valve elastic member  970  which elastically supports the valve switch member  960 . 
         [0127]    The upper case  910   a,  the middle case  901   b,  and the lower case  901   c  may be coupled by screws S. 
         [0128]    The low pressure sensor integrated relief valve  900  may also include an inlet  901  and an outlet  902  which are connected to the connection channel  200   a,  a spring support portion  951  which supports the pusher elastic member  950 , an adjusting screw  952  for adjusting an elastic force of the pusher elastic member  950 , a packing member  961  provided in the valve switch member  960  to seal the valve discharge channel  913 , an adjusting screw  980  for adjusting an elastic force of the valve elastic member  970 , and a valve support body  990  coupled to the valve body portion  910 . 
         [0129]    As the outlet  902  is inserted into the inlet of the solenoid switch valve  202 , the low pressure sensor integrated relief valve  900  may be installed at the solenoid switch valve  202 . 
         [0130]    The micro switch  940  may include an actuator  941  which protrudes to be pressed by the pusher  930 , and when the actuator  941  is pressed by the pusher  930 , the micro switch  940  may be turned off internally. 
         [0131]    When the actuator  941  is released from the pressure of the pusher  930 , the actuator  941  returns to an original state due to an elastic force of an elastic member in the micro switch  940 , and when the actuator  941  returns to the original state, the micro switch  940  may be turned on. 
         [0132]    However, the above-described operation of the micro switch  940  is only one example, when the pusher  930  presses the actuator  941 , the micro switch  940  may also be turned on, and when the actuator  941  is released from the pressure of the pusher  930 , the micro switch  940  may also be provided to be turned off, unlike the present embodiment. In the above-described case, the micro switch  940  has to be provided above the pusher  930  unlike the present embodiment. 
         [0133]    Meanwhile, when a pressure in the connection channel  200   a  is transferred to the valve main channel  911  using the above-described structure, as illustrated in  FIG. 14 , and the pressure in the connection channel  200   a  is greater than a predetermined replacement pressure (about 7.3 to 7.7 bar) and smaller than a predetermined pressure limit (about 9.5 to 11.5 bar), the pusher  930  overcomes an elastic force of the pusher elastic member  950 , moves in one direction, and presses the actuator  941  of the micro switch  940 , and the micro switch  940  is turned off. The valve switch member  960  moves in one direction due to an elastic force of the valve elastic member  970 , and closes the valve discharge channel  913 . 
         [0134]    As illustrated in  FIG. 15 , when the pressure in the connection channel  200 , that is the pressure in the connection channel  200   a,  is greater than the predetermined pressure limit (about 9.5 to 11.5 bar), the valve switch member  960  overcomes an elastic force of the valve elastic member  970 , moves in a direction opposite the one direction, and opens the valve discharge channel  913 . 
         [0135]    As illustrated in  FIG. 16 , when a pressure in the connection channel  200   a  is less than the predetermined replacement pressure (about 7.3 to 7.7 bar), the pusher  930  moves in a direction opposite the one direction due to an elastic force of the pusher elastic member  950 , and is separated from the micro switch  940 , and the micro switch  940  turns on. 
         [0136]    When the micro switch  940  is turned on, the micro switch  940  sends a low pressure signal to the controller  310 . 
         [0137]    As described above, as the low pressure sensor which senses a pressure when a pressure of carbon dioxide is less than the predetermined replacement pressure, and the relief valve which discharges carbon dioxide to the atmosphere when the pressure of the carbon dioxide is greater than the predetermined pressure limit are integrated, components may be simplified and assembly may be easy compared to a structure in which a low pressure sensor and a relief valve are provided separately. In addition, since a space occupied thereby decreases, the utilization of the space may be improved. 
         [0138]      FIG. 18  is a view illustrating a replacement notifier of a carbon dioxide cylinder of the refrigerator of  FIG. 11 , and  FIG. 19  is a control block diagram of the refrigerator of  FIG. 11 . 
         [0139]    A control method of the refrigerator according to another embodiment of the present invention will be described with reference to  FIGS. 18 and 19 . 
         [0140]    The refrigerator according to another embodiment of the present invention may further include an input portion  300  through which discharging of carbonated water or purified water is input, a display portion  320  which indicates whether carbonated water is generated or not, and a controller  310  which controls an opening or closing of an exhaust valve  251 , a solenoid switch valve  202 , a water supply solenoid valve  211 , a water discharge solenoid valve  221 , and an carbonated water discharge solenoid valve  231 , and an operation of the display portion  320  based on information received from a water level sensor  111 , a temperature sensor  112 , and the input portion  300 . 
         [0141]    The controller  310  may receive a low pressure signal sent from the micro switch  940  of the low pressure sensor integrated relief valve  900 , and may control an operation of the display portion  320 . 
         [0142]    The input portion  300  and the display portion  320  may be provided in an integrated display unit  330 , and the display portion  320  may include a notifier  321  which notifies of the replacement time of the carbon dioxide cylinder  120 . 
         [0143]    The low pressure sensor integrated relief valve  900  may sense a pressure of carbon dioxide in the connection channel  200   a.    
         [0144]    When the sensed pressure is less than a predetermined replacement pressure, the low pressure sensor integrated relief valve  900  may send the low pressure signal to the controller  310 , and the controller  310  may control the notifier  321  of the display portion  320  to notify of a replacement time. 
         [0145]    When the sensed pressure is greater than a predetermined pressure limit, the low pressure sensor integrated relief valve  900  is mechanically opened and may discharge carbon dioxide in the connection channel  200   a  to the atmosphere. 
         [0146]    Although the scope of the present invention is described with reference to specific embodiments, the scope of the present invention is not limited to the embodiments. Various other embodiments that may be changed or modified by those skilled in the art without departing from the scope and spirit of the present invention defined by the appended claims fall within the scope of the present invention.