Patent Publication Number: US-9421503-B2

Title: Refrigerator equipped with apparatus for producing carbonated water

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2013-0022345, filed on Feb. 28, 2013 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Embodiments of the present disclosure relate to coupling of a carbon dioxide gas cylinder in a refrigerator equipped with an apparatus for producing carbonated water. 
     2. Description of the Related Art 
     A refrigerator is a home appliance including a storage chamber to store food, and a cold air supplier to supply cold air to the storage chamber in order to keep food fresh. To satisfy consumer demand, such a refrigerator may be provided with an icemaker to make ice, and a dispenser to allow the user to take water or ice out of the refrigerator from outside of the refrigerator without opening a door. 
     The refrigerator may also be provided with a carbonated water production apparatus for producing carbonated water. The carbonated water production apparatus includes a carbon dioxide gas cylinder storing high-pressure carbon dioxide gas, and a carbonated water tank to produce carbonated water through mixing of carbon dioxide gas with water. 
     Carbonated water produced in the carbonated water tank may be connected to an external dispensation space via a dispenser in order to allow the user to retrieve carbonated water from outside of the refrigerator without opening the door. 
     In order to check an internal state of the carbonated water tank which produces and discharges carbonated water, for handling of carbonated water, it is necessary to install a sensor capable of sensing an internal state of the carbonated water tank. When the sensor is directly coupled to the carbonated water tank, or lines to guide carbonated water, clean water, and carbon dioxide gas, for introduction and discharge thereof, are directly coupled to the carbonated water tank, coupling areas may exhibit weak resistance to pressure or water leakage may occur at the coupling areas. 
     Meanwhile, since high-pressure carbon dioxide gas is introduced into the carbonated water tank, and carbonated water is stored in the carbonated water tank, the carbonated water tank is typically made of a material exhibiting high resistance to pressure and rust. When the sensor or lines are directly coupled to the carbonated water tank, which is made of the above-mentioned material, it may be difficult to obtain firm coupling. 
     SUMMARY 
     Therefore, it is an aspect of the present disclosure to provide a refrigerator having a carbonated water tank exhibiting high resistance to pressure while being capable of preventing leakage of water. 
     Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     In accordance with one aspect, a refrigerator includes a body, a carbonated water tank to produce carbonated water through mixing of clean water with carbon dioxide gas, a sensor unit inserted, at least a portion thereof, into the carbonated water tank, to sense an internal state of the carbonated water tank, and a holding unit disposed at one side of the carbonated water tank while holding the sensor unit in a fixed state. 
     The holding unit may have a cover shape to cover one side of the carbonated water tank. 
     The holding unit may include a holding plate, to which the sensor unit is fixed, and a plate support provided at a peripheral portion of the holding plate, to be supported by the carbonated water tank. 
     The refrigerator may further include a gasket provided between the carbonated water tank and the holding unit such that the gasket contacts one side of the carbonated water tank, to prevent occurrence of water leakage from the carbonated water tank. 
     The carbonated water tank may include a tank hole formed at one side of the carbonated water tank, to receive the at least a portion of the sensor unit. 
     The holding unit may further include a unit guide extending from a lower surface of the holding plate, to have a protruded shape, the unit guide having a hollow portion to guide the sensor unit. 
     The sensor unit may include a water level sensor. The holding unit may include a sensor seat to fix the water level sensor. 
     The water level sensor may include a sensor flange provided at one end of the water level sensor, to be seated on the sensor seat. 
     The water level sensor may be fixed, at one end thereof, to the holding unit while being provided, at the other end thereof, with a water level sensing rod extending into the carbonated tank. 
     The water level sensing rod may include a ground rod to set a reference for sensing of water level, a low water level sensing rod having a long length, to approach a bottom of the carbonated water tank so as to sense a low water level, and a high water level sensing rod having a shorter length than the low water level sensing rod, to approach a top of the carbonated water tank so as to sense a high water level. 
     The refrigerator may further include lines to guide the clean water, the carbon dioxide gas, and the carbonated water. The holding unit may include fitting tubes each fixed, at one end thereof, to the holding unit while communicating, at the other end thereof, with a corresponding one of the lines. 
     The carbonated water tank may be provided, at one side thereof, with line guides extending from the carbonated water tank, to have a protruded shape, each of the line guides having hollow portion to be coupled, at an end thereof, with one end of a corresponding one of the fitting tubes. 
     The refrigerator may further include a water tank to store the clean water, and a carbon dioxide gas cylinder stored with the carbon dioxide gas. 
     The sensor unit may be threadedly coupled to the holding unit. 
     The carbonated water tank may be made of a stainless steel material. 
     In accordance with one aspect, a refrigerator includes a body, a storage chamber defined in the body while having an opened front side, a door to open or close the opened front side of the storage chamber, a water tank to store clean water, a carbonated water production module mounted to a back surface of the door, the carbonated water production module including a carbon dioxide gas cylinder stored with carbon dioxide gas, and a carbonated water tank to produce carbonated water through mixing of the clean water with the carbon dioxide gas, a sensor unit to sense an internal state of the carbonated water tank, and a holding unit disposed at one side of the carbonated water tank while holding the sensor unit and lines to guide the clean water and the carbon dioxide gas in a fixed state. 
     The refrigerator may further include a gasket provided between the carbonated water tank and the holding unit such that the gasket contacts one side of the carbonated water tank, to prevent leakage of the carbonated water. 
     The sensor unit may include at least one of a water level sensor to sense a water level of the carbonated water tank, a relief valve to adjust an excessive internal pressure of the carbonated water tank, and a temperature sensor to sense a temperature of the carbonated water in the carbonated water tank. 
     In accordance with one aspect, a refrigerator includes a body, a storage chamber defined in the body while having an opened front side, a door to open or close the opened front side of the storage chamber, and a carbonated water production module mounted to a back surface of the door, to produce carbonated water, wherein the carbonated water tank includes a carbonated water tank to produce and store carbonated water, and a holding unit disposed at one side of the carbonated water tank while being inserted, at least a portion thereof, into the carbonated water tank, to hold at least one sensor unit in a fixed state. 
     The refrigerator may further include a gasket provided between the carbonated water tank and the holding unit such that the gasket contacts one side of the carbonated water tank, to prevent occurrence of water leakage from the carbonated water tank. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a perspective view illustrating an appearance of a refrigerator according to an embodiment; 
         FIG. 2  is a perspective view illustrating an interior of the refrigerator illustrated in  FIG. 1 ; 
         FIG. 3  is an exploded perspective view illustrating an assembled structure of a carbonated water production module in the refrigerator of  FIG. 1 ; 
         FIG. 4  is a perspective view illustrating the carbonated water production module in the refrigerator of  FIG. 1  in a state in which a cover is separated; 
         FIG. 5  is a conceptual view explaining carbonated water production and discharge procedures in the refrigerator of  FIG. 1 ; 
         FIG. 6  is a block diagram explaining a control method of the refrigerator illustrated in  FIG. 1 ; 
         FIG. 7  is a perspective view illustrating an interior of a refrigerator according to one embodiment; 
         FIG. 8A  is a perspective view illustrating the carbon dioxide gas cylinder along with a safety device included in the refrigerator in accordance with an embodiment; 
         FIG. 8B  is an exploded perspective view illustrating the carbon dioxide gas cylinder and safety device according to the illustrated embodiment; 
         FIGS. 8C and 8D  are views illustrating operations of the safety device according to the illustrated embodiment; 
         FIG. 8E  is a sectional view illustrating coupling of the carbon dioxide gas cylinder to a gas regulator according to an embodiment; 
         FIG. 8F  is a perspective view illustrating coupling of the carbon dioxide gas cylinder to the gas regulator; 
         FIG. 9A  is a perspective view illustrating an arrangement of the carbonated water regulator according to an embodiment; 
         FIGS. 9B and 9C  are sectional views illustrating operations of the carbonated water regulator according to the illustrated embodiment; 
         FIG. 10A  is a perspective view illustrating a carbonated water tank and a holding unit according to an embodiment; 
         FIG. 10B  is an exploded perspective view of the carbonated water tank and holding unit according to the illustrated embodiment; 
         FIG. 10C  is a perspective view illustrating a bottom of the holding unit; 
         FIG. 11A  is a perspective view illustrating arrangement of a water leakage sensor according to an embodiment; 
         FIG. 11B  is a cross-sectional view taking along the line A-A′ of  FIG. 11A ; 
         FIG. 11C  is a view illustrating coupling of the water leakage sensor according to the illustrated embodiment; 
         FIG. 11D  is a view illustrating operation of the water leakage sensor according to the illustrated embodiment; 
         FIG. 12A  is a perspective view illustrating an arrangement of a relief valve according to an embodiment; 
         FIG. 12B  is a sectional view illustrating a coupled state of the relief valve according to the illustrated embodiment; and 
         FIG. 12C  is a view illustrating operation of the relief valve according to the illustrated embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the preferred embodiments, examples of which are illustrated in the accompanying drawings. 
       FIG. 1  is a perspective view illustrating an appearance of a refrigerator according to an embodiment.  FIG. 2  is a perspective view illustrating an interior of the refrigerator illustrated in  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , the refrigerator according to the illustrated embodiment of the present invention which is designated by reference numeral “ 1 ” may include a body  10 , and a storage chambers  20  and  30  defined in an interior of the body  10 . The refrigerator  1  may further include a cold air supplier (not shown). 
     The body  10  may include an inner case to define the storage chambers  20  and  30 , and an outer case coupled to the inner case at an outside of the inner case, to define the appearance of the refrigerator  1 , and an insulator disposed between the inner and outer cases, to insulate the storage chambers  20  and  30 . 
     The storage chambers  20  and  30  may be divided into an upper refrigerating compartment  20  and a lower freezing compartment  30  by an intermediate barrier wall  11 . The refrigerating compartment  20  is kept at a temperature of 3° C., to store food in a refrigerated state, whereas the freezing compartment  30  is kept at a temperature of −18.5° C., to store food in a frozen state. Racks  23  may be provided at the refrigerating compartment  20 , to place food thereon. In the refrigerating compartment  20 , at least one storage box  27  may also be provided to store food in a closed state. 
     In addition, an ice making compartment  81  to produce ice may be provided at an upper corner of the refrigerating compartment  20 . The ice making compartment  81  may be partitioned from the refrigerating compartment  20  by an ice making compartment case  82 . In the ice making compartment  81 , an icemaker  80  may be provided. The icemaker  80  may include an ice making tray to produce ice, and an ice bucket to store ice produced in the ice making tray. 
     Meanwhile, a water tank  70  capable of storing water may be provided at the refrigerating compartment  20 . When a plurality of storage boxes  27  is provided, the water tank  70  may be disposed between adjacent ones of the storage boxes  27 , as illustrated in  FIG. 2 . Of course, embodiments of the present invention are not limited to the illustrated case. The water tank  70  may be disposed at any position, so long as it is disposed within the refrigerating compartment  20  in order to cool water stored in the water tank  70  by cold air present in the refrigerating compartment  20 . 
     The water tank  70  may be connected to an external water supply source  40  ( FIG. 5 ) such as a tap water supply source. The water tank  70  may store clean water purified by a purification filter  50  ( FIG. 5 ). A path change valve  60  may be provided at a water supply tube to connect the water tank  70  to the external water supply source  40 . Through the path change valve  50 , water may be supplied to the icemaker  80 . 
     Each of the refrigerating compartment  20  and freezing compartment  30  has an opened front side to allow food to be place therein or retrieved therefrom. The opened front side of the refrigerating compartment  20  may be opened or closed by a pair of pivotable doors  21  and  22  pivotally coupled to the body  10 . The opened front side of the freezing compartment  30  may be opened or closed by a sliding door  31  slidable with respect to the body  10 . Door guards  24  capable of storing food may be provided at back surfaces of the refrigerating compartment doors  21  and  22 . 
     Meanwhile, a gasket  28  is provided along an edge of each refrigerating compartment door  21  or  22  at the back surface of the refrigerating compartment door  21  or  22 , to confine cold air in the refrigerating compartment  20  by providing a seal between the refrigerating compartment door  21  or  22  and the body  10 . A pivotable bar  26  may be provided at one of the refrigerating compartment doors  21  and  22 , for example, the refrigerating compartment door  21 , to provide a seal between the refrigerating compartment doors  21  and  22  when the refrigerating compartment doors  21  and  22  are closed, and thus to prevent cold air from leaking from the refrigerating compartment  20 . 
     In addition, a dispenser  90  may be provided at one of the refrigerating compartment doors  21  and  22 , for example, the refrigerating compartment door  21 , to allow the user to retrieve water or ice stored in the refrigerator  1  from the outside of the refrigerator  1  without opening the refrigerating compartment door  21 . 
     The dispenser  90  may include a dispensation space  91  to receive a container such as a cup in order to dispense water or ice into the container, a control panel  92  provided with input buttons to manipulate various settings of the dispenser  90  and a display to display various information of the dispenser  90 , and an operating lever  93  to operate the dispenser  90 , for dispensation of water or ice. 
     The dispenser  90  may also include an ice guide passage  94  to connect the dispensation space  91  to the icemaker  80  in order to discharge ice produced in the icemaker  80  into the dispensation space  91 . 
     Meanwhile, in the refrigerator  1  according to the illustrated embodiment, a carbonated water production module  100  to produce carbonated water may be mounted to the back surface of the refrigerating compartment door  21  where the dispenser  90  is provided. Hereinafter, the carbonated water production module  100  will be described in detail. 
       FIG. 3  is an exploded perspective view illustrating an assembled structure of the carbonated water production module in the refrigerator of  FIG. 1 .  FIG. 4  is a perspective view illustrating the carbonated water production module in the refrigerator of  FIG. 1  in a state in which a cover is separated.  FIG. 5  is a conceptual view explaining carbonated water production and discharge procedures in the refrigerator of  FIG. 1 . 
     The carbonated water production module  100  functions to produce carbonated water within the refrigerator  1 . As illustrated in  FIGS. 3 to 5 , the carbonated water production module  100  may include a carbon dioxide gas cylinder  120  stored therein with high-pressure carbon dioxide gas, and a carbonated water tank  110  to produce carbonated water through mixing of clean water with carbon dioxide gas. The carbonated water production module  100  also includes a module case  140  coupled to the back surface of the refrigerating compartment door  21  while being defined therein with accommodation spaces  151 ,  152 , and  153  to receive the carbon dioxide gas cylinder  120  and carbonated water tank  110 , and a valve assembly  130 . 
     Carbon dioxide gas at a high pressure of 45 to 60 bars may be stored in the carbon dioxide gas cylinder  120 . The carbon dioxide gas cylinder  120  may be received in the lower accommodation space  153  while being mounted to a cylinder connector  157  of the module case  140 . 
     Carbon dioxide gas in the carbon dioxide gas cylinder  120  may be supplied to the carbonated water tank  110  through a carbon dioxide gas supply line  200  which interconnects the carbon dioxide gas cylinder  120  and carbonated water tank  110 . 
     The carbon dioxide gas supply line  200  may be provided with a carbon dioxide gas regulator  201  to adjust the pressure of carbon dioxide gas, a carbon dioxide gas supply valve  202  to open or close the carbon dioxide gas supply line  200 , and a carbon dioxide gas backflow prevention valve  203  to prevent backflow of carbon dioxide gas. 
     The carbon dioxide gas regulator  201  may adjust the pressure of carbon dioxide gas discharged from the carbon dioxide gas cylinder  120  and, as such, pressure-adjusted carbon dioxide gas may be supplied to the carbonated water tank  110 . The carbon dioxide gas regulator  201  may reduce the pressure of carbon dioxide gas to about 10 bars. 
     The carbonated water tank  110  mixes carbon dioxide gas supplied from the carbon dioxide gas cylinder  120  with clean water supplied from the water tank  70 , thereby producing carbonated water. The carbonated water tank  110  may store the produced carbonated water. 
     In addition to the above-described carbon dioxide gas supply line  200 , a clean water supply line  210  to receive clean water from the water tank  70  may be connected to the carbonated water tank  110 . A carbonated water discharge line  230  to discharge the produced carbonated water into the dispensation space  91 , and an exhaust line  250  to exhaust carbon dioxide gas remaining in the carbonated water tank  110 , for supply of clean water to the carbonated water tank  110 , may also be connected to the carbonated water tank  110 . 
     A clean water supply valve  211  to open or close the clean water supply line  210  may be provided at the clean water supply line  210 . The carbonated water discharge line  230  may be provided with a carbonated water discharge valve  231  to open or close the carbonated water discharge line  230 , and a carbonated water regulator  800  to adjust the pressure of carbonated water discharged through the carbonated water discharge line  230 . An exhaust valve  251  to open or close the exhaust line  250  may be provided at the exhaust line  250 . 
     In this case, each of the clean water supply valve  211  and carbonated water discharge valve  231  may be a solenoid valve. 
     Meanwhile, the carbonated water tank  110  may be provided with a water level sensor  111  to measure the amount of clean water supplied to the carbonated water tank  110 , and a temperature sensor  112  to measure the temperature of clean water supplied to the carbonated water tank  110  or the temperature of carbonated water produced in the carbonated water tank  110 . 
     A relief valve  950  may also be provided at the carbonated water tank  110 . When carbon dioxide gas of a high pressure exceeding a predetermined pressure is supplied to the carbonated water tank  110  due to malfunction of the carbon dioxide gas regulator  201 , etc, the relief valve  950  discharges the carbon dioxide gas of the excessively high pressure. 
     The carbonated water tank  110  may be formed to have a predetermined size. For example, the carbonated water tank  110  may be formed to receive 1 l of carbonated water. The carbonated water tank  110  may be made of a stainless steel material in order to minimize the size of the carbonated water tank  110  while sustaining a high pressure and exhibiting corrosion resistance. The carbonated water tank  110  may be received in the first upper accommodation space  151  of the module case  140 . The carbonated water tank  110  may be supported by a bottom support  155  and a guide  156  which are included in the module case  140 . 
     Meanwhile, the above-described clean water supply valve  211  and carbonated water discharge valve  231  may constitute a valve assembly  130 , together with a clean water discharge valve  221  provided at the clean water discharge line  220  to directly discharge clean water into the dispensation space  91 . That is, the clean water supply valve  211 , carbonated water discharge valve  231 , and clean water discharge valve  221  may be integrated in the form of a single unit. In this case, the clean water discharge valve  221  may be implemented by a solenoid valve, as in the clean water supply valve  211  and carbonated water discharge valve  231 . 
     The valve assembly  130  may include a first inlet port  130   a  connected to the water tank  70 , and a second inlet port  130   b  connected to the carbonated water tank  110 . The valve assembly  130  may also include a first outlet port  130   c  connected to the carbonated water tank  110 , a second outlet port  130   d  connected to the dispensation space  91 , to discharge clean water, and a third outlet port  130   e  connected to the dispensation space  91 , to discharge carbonated water. 
     The clean water supply line  210  and clean water discharge line  220  may pass through the first inlet port  130   a . Through the second inlet port  130   b , the carbonated water discharge line  230  may pass. The clean water supply line  210  may pass through the first outlet port  130   c . The clean water discharge line  220  may pass through the second outlet port  130   d . Through the third outlet port  130   e , the carbonated water discharge line  230  may pass. 
     Of course, the clean water supply valve  211 , clean water discharge valve  221 , and carbonated water discharge valve  231  are independently opened or closed. Accordingly, supply of clean water from the water tank  70  to the carbonated water tank  110  and discharge of clean water from the water tank  70  into the dispensation space  91  may be carried out in a simultaneous manner. In addition, supply of clean water from the water tank  70  to the carbonated water tank  110  and discharge of carbonated water from the carbonated water tank  110  into the dispensation space  91  may be carried out in a simultaneous manner. 
     Although the valve assembly  130  is constituted by the three independent valves  211 ,  221 , and  231  as described above in the illustrated embodiment, it may be constituted by one three-way path change valve to selectively supply clean water from the water tank  70  to the carbonated water tank  110  or the dispensation space  91 , and another three-way path change valve to supply clean water from the water tank  70  to the dispensation space  91  or to supply carbonated water from the carbonated water tank  110  to the dispensation space  91 . 
     The above-described valve assembly  130  may be received in the second upper accommodation space  152  of the module case  140 . 
     Meanwhile, the clean water discharge line  220  to directly discharge clean water from the water tank  70  into the dispensation space  91  and the carbonated water discharge line  230  to discharge carbonated water from the carbonated water tank  110  into the dispensation space  91  may be joined at a certain point, to form a common discharge line  240 . 
     The clean water discharge line  200  and carbonated water discharge line  230  may be joined within the valve assembly  130  or at the second outlet port  130   d . Accordingly, the clean water discharge line  200  and carbonated water discharge line  230  may be unified to be provided in the dispensation space  91  in the form of a single line without being individually provided. Of course, the clean water discharge line  200  and carbonated water discharge line  230  may individually extend to the dispensation space  91  without being unified. 
     A remaining water discharge prevention valve  241  may be provided at the common discharge line  240 . The remaining water discharge prevention valve  241  opens or closes the common discharge line  240  in order to prevent clean water or carbonated water remaining in the common discharge line  240  from being discharged into the dispensation space  91  in closed states of the clean water discharge valve  221  and carbonated water discharge valve  231 . The remaining water discharge prevention valve  241  may be disposed at an end of the common discharge line  240 , if possible. 
     The module case  140  may include a back case  150  opened at one side thereof, and a cover  160  coupled to the opened side of the back case  150 . 
     The module case  140  may be formed with at least one fitting groove  154  at a position corresponding to at least one fitting protrusion  25  formed at the back surface of the door  21 . Accordingly, it may be possible to easily mount the module case  140  to the back surface of the door  21  by fitting the fitting protrusion  25  into the fitting groove  154 . Of course, such a coupling structure is illustrative. It may be possible to detachably mount the module case  140  to the back surface of the door  21 , using a thread fastening structure or a hook engagement structure, in place of the fitting structure. 
     In addition, the back case  150  and cover  160  may be formed with a fitting groove  158  and a fitting protrusion  162  at corresponding positions, respectively, and, as such, the cover  160  may be coupled to the back case  150 . Of course, such a coupling structure is illustrative. It may be possible to detachably couple the back case  150  and cover  160 , using various coupling structures. 
     Meanwhile, in a state in which the cover  160  is coupled to the back case  150 , the carbon dioxide gas cylinder  120 , carbonated water tank  110 , and valve assembly  130  received in the module case  140  may be prevented from being exposed to the outside. Accordingly, the aesthetics of the door  21  may not be degraded. 
     Of course, a louver  161  may be formed at the cover  160 , to communicate the interior of the module case  140  with the outside. Accordingly, even in a state in which the cover  160  is coupled to the back case  150 , cold air in the storage chamber may be supplied to the carbonated water tank  110  within the module case  140  and, as such, carbonated water stored in the carbonated water tank  110  may be cooled to an appropriate temperature or may be kept at the appropriate temperature. 
     The cover  160  may be divided into a first cover  160   a  to open or close the upper accommodation spaces  151  and  152 , in which the carbonated water tank  110  and valve assembly  130  are received, respectively, and a second cover  160   b  to open or close the lower accommodation space  153 , in which the carbon dioxide gas cylinder  120  is received. The first cover  160   a  and second cover  160   b  may be independently opened or closed. 
     Accordingly, when the carbon dioxide gas cylinder  120  is replaced with a new one due to exhaustion of carbon dioxide gas thereof, the replacement may be achieved by separating only the second cover  160   b  without opening the first cover  160   a . Thus, it may be possible to prevent cold air in the upper accommodation space  151  from being outwardly discharged during replacement of the carbon dioxide gas cylinder  120  because the first cover  160   a  is maintained in a closed state. 
     In other words, the carbonated water production module  100  in the refrigerator according to the illustrated embodiment may include a first module including the carbonated water tank  110  and the first accommodation space  151  to receive the carbonated water tank  110 , and a second module including the carbon dioxide gas cylinder  120  and the second accommodation space  153  to receive the carbon dioxide gas cylinder  120 . 
     In this case, the second module may be disposed beneath the first module. In addition, the second module may be disposed at one side of the ice guide passage  94  to guide ice from the icemaker  80  to the dispensation space  91 . 
     The first module may also include the first cover  160   a  to open or close the first accommodation space  151 . The second module may also include the second cover  160   b  opened or closed independently of the first cover  160   a , to open or close the lower accommodation space  153 . 
       FIG. 6  is a block diagram explaining a control method of the refrigerator illustrated in  FIG. 1 . 
     Hereinafter, carbonated water production and discharge procedures in the refrigerator according to an embodiment will be described with reference to  FIGS. 5 and 6 . 
     As illustrated in  FIG. 6 , the refrigerator according to the illustrated embodiment may further include an input unit  300  to input a command for discharge of carbonated water or discharge of clean water, and a display unit  320  to inform whether carbonated water has been produced, in addition to the above-described water level sensor  111 , temperature sensor  112 , exhaust valve  251 , carbon dioxide gas supply valve  202 , and the valve assembly  130  in which the clean water supply valve  211 , clean water discharge valve  221 , and carbonated water discharge valve  231  are integrally formed. The refrigerator may also include a water leakage sensor  900 . 
     The refrigerator may further include a control unit  310  to control opening and closing operations of the exhaust valve  251  and carbon dioxide gas supply valve  202 , opening and closing operations of the valve assembly  130 , in which the clean water supply valve  211 , clean water discharge valve  221 , and carbonated water discharge valve  231  are integrally formed, and operation of the display unit  320 , based on information received from the water level sensor  111 , temperature sensor  112 , water leakage sensor  900 , and input unit  300 . 
       FIG. 7  is a perspective view illustrating an interior of a refrigerator according to another embodiment. 
     As illustrated in  FIG. 7 , the idea of the illustrated embodiment, for example, may be applied to a side-by-side (SBS) type refrigerator as well as the above-described French door refrigerator (FDR) type refrigerator or any type of appliance that supplies drinking water. The refrigerator which is designated by reference numeral “ 600 ” may include storage chambers  620  and  630  laterally divided from each other by a vertical barrier wall  611 . 
     Each of the storage chambers  620  and  630  may be used as a refrigerating compartment or a freezing compartment.  FIG. 7  illustrates an example in which the left storage chamber  620  is used as a refrigerating compartment, and the right storage chamber  630  is used as a freezing compartment. In the following description, the left storage chamber  620  will be referred to as a “refrigerating compartment  620 ”, and the right storage chamber  630  will be referred to as a “freezing compartment  630 ”. 
     Each of the refrigerating compartment  620  and freezing compartment  630  may be opened at a front side thereof. The front sides of the refrigerating compartment  620  and freezing compartment  630  may be opened or closed by a pair of pivotable doors  621  and  631 , respectively. Door guards  624  capable of storing food may be provided at each of the doors  621  and  631 . 
     A water tank  670  capable of storing water may be provided at the refrigerating compartment  620 . Clean water stored in the water tank  670  may be naturally cooled by cold air present in the refrigerating compartment  620 . A dispenser  690  may be provided at the refrigerating compartment doors  21  and  22 , for example, the refrigerating compartment door  621 , to allow the user to retrieve water or ice stored in the refrigerator from the outside of the refrigerator without opening the refrigerating compartment door  621 . An ice guide passage  704  may be provided at the dispenser  690 , to guide ice. 
     A carbonated water production module  700  having the same structure as that of the refrigerator according to the previous embodiment of the present invention may be mounted to the back surface of the refrigerating compartment door  621 . 
       FIG. 8A  is a perspective view illustrating the carbon dioxide gas cylinder along with a safety device included in the refrigerator in accordance with an embodiment.  FIG. 8B  is an exploded perspective view illustrating the carbon dioxide gas cylinder and safety device according to the illustrated embodiment.  FIGS. 8C and 8D  are views illustrating operations of the safety device according to the illustrated embodiment.  FIG. 8E  is a sectional view illustrating coupling of the carbon dioxide gas cylinder to a gas regulator according to an embodiment  FIG. 8F  is a perspective view illustrating coupling of the carbon dioxide gas cylinder to the gas regulator. 
     The carbon dioxide gas cylinder  120  is disposed in the lower accommodation space  153  of the carbonated water production module  100 . When the carbon dioxide gas cylinder  120  is connected to the cylinder connector  157 , carbon dioxide gas is supplied to the carbonated water tank  110  in a pressure-reduced state via the gas regulator  201 . 
     The safety device which is designated by reference numeral “ 750 ” includes a safety lever  752  pivotably mounted to the cylinder connector  157  coupled to one side of the carbon dioxide gas cylinder  120 , and a safety lever  752  pivotably mounted to opposite sides of the gas regulator  201 , to selectively move the carbon dioxide gas cylinder  120  toward or away from the gas regulator  201  in accordance with pivotal movement thereof. 
     The cylinder connector  157  has a configuration to allow the carbon dioxide gas cylinder  120  to be coupled, at one side thereof, to the cylinder connector  157 . For this configuration, the cylinder connector  157  includes a cylindrical cylinder connector body  157   a  opened at one side thereof, and a cylinder connector hole  157   b  provided at the other side of the cylinder connector body  157   a , namely, a closed side of the cylinder connector body  157   a  opposite to the opened side, to allow a push rod  201   c  to extend therethrough. The push rod  201   c  is provided at the gas regulator  201 , to guide carbon dioxide gas from the carbon dioxide gas cylinder  120 . 
     The cylinder connector body  157   a  has a configuration defining an appearance of the cylinder connector  157 . That is, the cylinder connector body  157   a  has a cylindrical shape opened at one side thereof. Cylinder connector moving pins  157   c  are provided at a side portion of the cylinder connector body  157   a , namely, a cylindrical portion of the cylinder connector body  157   a . The cylinder connector moving pins  157   c  are protruded from opposite sides of the cylindrical portion of the cylinder connector body  157   a , respectively. The cylinder connector moving pins  157   c  are moved by the safety lever  752  and a safety lever holder  760 , to couple or separate the carbon dioxide gas cylinder  120  to or from the gas regulator  201 . 
     An outlet portion of the carbon dioxide gas cylinder  120  is fitted in a gas cylinder coupling portion  157   d  formed at the opened side of the cylinder connector body  157   a . Threads are formed at an inner peripheral surface of the gas cylinder coupling portion  157   d , namely, an inner surface of the cylindrical portion of the cylinder connector body  157   a . On the other hand, threads are formed at an outer peripheral surface of the outlet portion of the carbon dioxide cylinder  120  which has a cylindrical shape. Accordingly, it may be possible to threadedly couple the carbon dioxide gas cylinder  120  to the cylinder connector  157  after bring the carbon dioxide gas cylinder  120  into contact with the cylinder connector  157 , and then rotating the carbon dioxide gas cylinder  120 . 
     The cylinder connector hole  157   b  is provided at the other side of the cylinder connector  157  corresponding to the outlet portion of the carbon dioxide gas cylinder  120 . The cylinder connector hole  157   b  allows the push rod  201   c , which is provided at the gas regulator  201  while having a tubular shape to guide carbon dioxide gas from the carbon dioxide gas cylinder  120 , to be inserted into the outlet portion of the carbon dioxide gas cylinder  120  after passing through the cylinder connector hole  157   b  provided at the other side of the cylinder connector body  157   a.    
     As illustrated in  FIG. 8E , the cylinder connector  157  and gas regulator  201  are kept spaced apart from each other by a predetermined distance, even in a coupled state of the carbon dioxide gas cylinder  120 . As a result, even when the carbon dioxide gas cylinder  120  is coupled to the cylinder connector  157 , it may be possible to prevent the push rod  201   c  from being coupled to an outlet of the carbon dioxide gas cylinder  120  without operation of the safety device  750 . The push rod  201   c  comes into contact with the outlet of the carbon dioxide gas cylinder  120 , to be coupled to each other, only when the safety device  750  operates. The predetermined distance is 5 mm. 
     The safety lever  752  includes a lever portion  754  to receive force, and lever legs  756  each having a pivot pin hole  756   a . The safety lever  752  may be pivotably coupled to the gas regulator  201  by a pivot pin extending through the pivot pin holes  756   a  of the lever legs  756  and a hole formed through the gas regulator  201 . The safety lever  752  also includes cylinder connector pushing portions  758  provided at respective lever legs  756 , to push respective cylinder connector moving pins  157   c . The safety lever  752  is disposed at the front side of the gas regulator  201 . 
     The lever portion  754  is vertically pivotable about the pivot pin extending through the pivot pin holes  756   a  provided at the lever legs  756 . In accordance with vertical pivotal movement of the lever portion  754 , the cylinder connector  157  is coupled to or separated from the gas regulator  201 . 
     The lever legs  756  extend from opposite lateral ends of the lever portion  754  in a bent state, respectively. As described above, the lever legs  756  have respective pivot pin holes  756   a  and, as such, the lever portion  754  is pivotable with respect to the lateral sides of the gas regulator  201 . 
     The cylinder connector pushing portions  758  are protruded from respective lever legs  756 . The cylinder connector pushing portions  758  have a curvature about the pivot pin holes  756   a  different from that of the lever legs  756 . The cylinder connector pushing portions  758  support top portions of the cylinder connector moving pins  157   c , respectively. Through such a configuration, the cylinder connector pushing portions  758  are directed to the cylinder connector moving pins  157   c  during upward movement of the lever portion  754  while being directed to a back side of the gas regulator  201  during downward movement of the lever portion  754 . In detail, when the lever portion  754  moves downward to bring the cylinder connector  157  into close contact with the gas regulator  201 , the cylinder connector pushing portions  758  do not interfere with the cylinder connector moving pins  157   c  because they are directed to the back side of the gas regulator  201 . However, when the lever portion  754  moves upward to cause the cylinder connector  157  to be spaced apart from the gas regulator  201 , the cylinder connector pushing portions  758  move the cylinder connector  157  downward because it is directed to the cylinder connector moving pins  157   c  and, as such, the cylinder connector  157  is spaced apart from the gas regulator  201 . 
     The safety device  750  further includes the safety lever holder  760 . The safety lever holder converts rotational movement of the safety lever  752  into extension or retraction movement of the cylinder connector  157 . 
     The safety lever holder  760  is disposed at the back side of the gas regulator  201 . The safety lever holder  760  includes holder coupling holes to be coupled with the safety lever  752 , and cylinder connector seating grooves  760   a , in which respective cylinder connector moving pins  157   c  are seated. 
     Safety lever coupling pins  756   b  are provided at respective lever legs  756  of the safety lever  752 , for coupling of the safety lever holder  760  to the safety lever  752 . The safety lever coupling pins  756   b  are spaced apart from respective pivot pin holes  756   a . The safety lever coupling pins  756   b  are disposed at positions opposing the lever portion  754  with respect to respective pivot pin holes  756   a . Accordingly, the safety lever holder  760  is pivotally moved about the pivot pin holes  756   a  in accordance with pivotal movement of the safety lever  752 . Holder coupling holes  760   b  are provided at the safety lever holder  760 , to be coupled with respective safety lever coupling pins  756   b . As the holder coupling holes  760   b  of the safety lever holder  760  are coupled with respective safety lever coupling pins  756   b , pivotal movement of the safety lever  752  is transmitted to the safety lever holder  760 . In detail, when the lever portion  754  performs upward pivotal movement about the pivot pin holes  756   a , the safety lever coupling pins  756   b  and holder coupling holes  760   b  are moved upward, thereby causing the safety lever holder  760  to be moved upward. On the other hand, when the lever portion  754  performs downward pivotal movement about the pivot pin holes  756   a , the safety lever coupling pins  756   b  and holder coupling holes  760   b  are moved downward, thereby causing the safety lever holder  760  to be moved downward. 
     As described above, the cylinder connector seating grooves  760   a  are provided at the safety lever holder  760  and, as such, the cylinder connector moving pins  157   c  are seated in respective cylinder connector seating grooves  760   a . Each cylinder connector seating groove  760   a  is formed at the safety lever holder  760  in a concave shape. Each cylinder connector seating groove  760   a  supports a bottom side of the cylinder connector moving pin  157   c  seated therein. Thus, the cylinder connector moving pins  157   c  are moved upward in accordance with upward movement of the safety lever holder  760 . 
     The safety device  750  also includes a cylinder connector guide  770  disposed to enclose the cylinder connector  157 . The cylinder connector guide  770  is opened at one side thereof in order to enclose the cylinder connector  157 . Cylinder connector guide grooves  770   a  are provided at opposite sides of the cylinder connector guide  770 , to guide upward and downward movements of the cylinder connector moving pins  157   c.    
     Gas regulator pivot pins  201   a  are provided at opposite sides of the gas regulator  201 , to pivotally move the gas regulator  201 . Through such a configuration, the push rod of the carbon dioxide gas cylinder  120  may be forwardly directed during replacement of the carbon dioxide gas cylinder  120  and, as such, replacement of the carbon dioxide gas cylinder  120  may be easily achieved. The gas regulator pivot pins  201   a  may protrude from opposite side surfaces of the gas regulator  201 . Alternatively, separate pivot pins may be provided as the gas regulator pivot pins  201   a . In this case, the gas regulator pivot pins  201   a  may be coupled to the gas regulator  201 . 
     The gas regulator  201  is enclosed, at an outer surface thereof, by a gas regulator case  201   b . Accordingly, it may be possible to protect the configuration of the gas regulator  201  from an external environment. 
     A gas cylinder guide  780  to guide the cylindrical carbon dioxide gas cylinder  120  is provided at one side of the carbon dioxide gas cylinder  120 . Although there is no limitation as to the position of the gas cylinder guide  780 , the gas cylinder guide  780  is disposed at the back side of the carbon dioxide gas cylinder  120 , taking into consideration aesthetics and space utilization. 
     The gas cylinder guide  780  includes a cylinder contact portion  780   a  to contact at least a side surface of the cylindrical carbon dioxide gas cylinder  120  in a longitudinal direction of the cylindrical carbon dioxide gas cylinder  120 , a cylinder spacing portion  780   b  provided at the cylinder contact portion  780   a , to be spaced apart from the carbon dioxide gas cylinder  120  by a predetermined spacing, and a cylinder seating portion  780   c  in which a lower portion of the carbon dioxide gas cylinder  120  is seated. 
     The cylinder contact portion  780   a  contacts one side of the carbon dioxide gas cylinder  120 , to prevent the carbon dioxide gas cylinder  120  from vibrating or moving. One end of the cylinder contact portion  780   a  is coupled to the gas regulator  201  or gas regulator case  201   b . When the gas regulator  201  pivots about the gas regulator pivot pins  201   a , the cylinder contact portion  780   a  is pivoted along with the gas regulator  201 . 
     The cylinder spacing portion  780   b  is formed at an intermediate region of the cylinder contact portion  780   a  so as to outwardly protrude from the cylinder contact portion  780   a , to be spaced apart from the carbon dioxide gas cylinder  120  by the predetermined spacing. The predetermined spacing provides a space into which the hand of the user may be inserted when the user rotates the carbon dioxide gas cylinder  120  while grasping the carbon dioxide gas cylinder  120  upon coupling or separation of the carbon dioxide gas cylinder  120  to or from the cylinder connector  157 . There is no limitation as to the predetermined spacing, so long as the predetermined spacing provides a space into which the hand of the user may be inserted when the user grasps the carbon dioxide gas cylinder  120 . 
     The cylinder seating portion  780   c  is configured to receive the lower portion of the carbon dioxide gas cylinder  120 . Since the carbon dioxide gas cylinder  120  has a cylindrical shape, the cylinder seating portion  780   c  also has a cylindrical shape opened at one side thereof. 
     Hereinafter, operation of the safety device  750  according to the above-described configuration will be described. 
     Upon replacement of the carbon dioxide gas cylinder  120 , the gas regulator  201  and gas cylinder guide  780  are pivoted about the gas regulator pivot pins  201   a , to be forwardly directed, as illustrated in  FIG. 8F . 
     Thereafter, the carbon dioxide gas cylinder  120  is coupled to the cylinder connector  157  by threadedly coupling the threads provided at the outer peripheral surface of the outlet portion of the carbon dioxide gas cylinder  120  to the threads provided at the inner peripheral surface of the cylinder connector  157 . 
     Subsequently, the lever portion  754  of the safety lever  752  is moved downward, as illustrated in  FIG. 8D . In accordance with the downward movement of the lever portion  754 , the safety lever  752  is pivoted about the pivot pin mounted in the pivot pin holes  756   a . As a result, the safety lever coupling pins  756   b  and holder coupling holes  760   b  are moved upward, thereby causing the safety lever holder  760  to be moved upward. 
     The cylinder connector moving pins  157   c  of the cylinder connector  157  seated in the cylinder connector seating grooves  760   a  of the safety lever holder  760  are also moved upward. As a result, the cylinder connector  157  comes into close contact with the gas regulator  201  and, as such, the carbon dioxide gas cylinder  120  and gas regulator  201  are coupled to each other. 
     Upon separating the carbon dioxide gas cylinder  120  and gas regulator  201  from each other, the lever portion  754  of the safety lever  752  is moved upward, as illustrated in  FIG. 8C . In this case, the safety lever  752  is pivoted about the pivot pin mounted in the pivot pin holes  756   a . As a result, the safety lever coupling pins  756   b  and holder coupling holes  760   b  are moved downward, thereby causing the safety lever holder  760  to be moved downward. 
     In this case, the cylinder connector pushing portions  758  provided at respective lever legs  756  of the safety lever  752  is pivoted, thereby pushing the cylinder connector moving pins  157   c . As a result, the cylinder connector moving pins  157   c  are moved downward and, as such, the cylinder connector  157  is spaced away from the gas regulator  201 . Thus, the carbon dioxide gas cylinder  120  is separated from the gas regulator  201 . 
       FIG. 9A  is a perspective view illustrating an arrangement of the carbonated water regulator according to an embodiment.  FIGS. 9B and 9C  are sectional views illustrating operations of the carbonated water regulator according to the illustrated embodiment. 
     Clean water from the water tank  70  is supplied to the carbonated water tank  110  via the clean water supply line  210 . When a predetermined amount of clean water is supplied, high-pressure carbon dioxide gas from the carbon dioxide gas cylinder  120  is introduced into the carbonated water tank  110 , to produce carbonated water. The produced carbonated water is then forcibly discharged into the dispensation space  91  via the carbonated water discharge line  230  by the pressure of high-pressure carbon dioxide gas in the carbonated water tank  110 . 
     The high-pressure carbon dioxide gas stored in the carbon dioxide gas cylinder  120  is maintained at a pressure of about 45 to 60 bars, and is supplied to the carbonated water tank  110  at a pressure of 10 bars after passing through the gas regulator  201 . Carbonated water from the carbonated water tank  110  is forcibly discharged by the pressure of high-pressure carbon dioxide gas present within the carbonated water tank  110 . Since carbonated water from the carbonated water tank  110  is discharged at a pressure of about 5 to 8 bars, frying of carbonated water may occur during dispensation of the carbonated water due to the pressure of carbon dioxide gas. 
     The carbonated water regulator  800  is a configuration to control carbonated water from the carbonated water tank  110  to be discharged at a predetermined pressure. 
     The carbonated water regulator  800  is provided at the carbonated water discharge line extending from the carbonated water tank  110  to the dispensation space  91 . 
     In detail, the carbonated water regulator  800  is provided at the carbonated water discharge line which includes the carbonated water discharge line  230 , the clean water discharge line  220 , and the valve assembly  130  to open or close the clean water supply line  210 , to connect the carbonated water tank  110  to the dispensation space  91 . 
     As described above, the valve assembly  130  includes the first inlet port  130   a  connected to the water tank  70 , the second inlet port  130   b  connected to the carbonated water tank  110 , the first outlet port  130   c  connected to the carbonated water tank  110 , for supply of clean water, the second outlet port  130   d  connected to the dispensation space  91 , to discharge clean water, and the third outlet port  130   e  connected to the dispensation space  91 , to discharge carbonated water. The carbonated water regulator  800  is provided at the carbonated water discharge line  230  which passing through the second inlet port  130   b  and third outlet portion  130   e  of the valve assembly  130  while extending from the carbonated water tank  110 . 
     Through the above-described configuration, carbonated water discharged from the carbonated water tank  110  completely passes through the carbonated water regulator  800 . 
     As carbonated water passes through the carbonated water regulator  800 , it may be discharged through the third outlet portion  130   e  after being maintained at a predetermined pressure or below. 
     The carbonated water regulator  800  includes a regulator body  801  to define the appearance of the carbonated water regulator  800 , a static pressure hole  802  to allow carbonated water to flow through the carbonated water regulator body  801 , and an opening/closing member  804  to open or close at least a portion of the static pressure hole  802 . 
     The regulator body  801 , which defines the appearance of the carbonated water regulator  800 , includes a carbonated water inlet  812  arranged at one side of the regulator body  801 , to receive carbonated water, and a carbonated water outlet  814  arranged at the other side of the regulator body  801 , to allow carbonated water to be discharged from the regulator body  801  after passing through the regulator body  801 . 
     The static pressure hole  802  is provided at an inside of the regulator body  801 , to be opened or closed in accordance with movement of the opening/closing member  804 . The static pressure hole  802  is arranged in a flow path of carbonated water defined in the regulator body  801 . 
     The static pressure hole  802  has a circular shape, and the opening/closing member  804  has a conical shape having a circular cross-section. Accordingly, the area occupied by the opening/closing member  804  in the static pressure hole  802  is varied in accordance with movement of the opening/closing member  804  through the static pressure hole  802 . Thus, it may be possible to adjust an amount of carbonated water passing through the static pressure hole  802 . 
     The opening/closing member  804  has a rod-shaped body, and an end having a conical shape. In the opening/closing member  804 , the longitudinal cross-section of the end is greater than that of the body. The body is supported by regulator elastic members  806  and, as such, the opening/closing member  804  is movable in an extension or retraction direction by tensions of the regulator elastic members  806 . 
     The carbonated water regulator  800  further includes at least one regulator elastic member  806  which may be tensed in accordance with pressure of carbonated water, to move the opening/closing member  804  in an extension or retraction direction. 
     In the illustrated embodiment, the at least one regulator elastic member  806  includes first and second regulator elastic members  806   a  and  806   b  disposed at opposite sides of the static pressure hole  802  while being connected by a balance rod  808 . The first regulator elastic member  806   a  moves the balance rod  808  in accordance with a pressure of carbonated water at one side of the static pressure hole  802 , whereas the second regulator elastic member  806   b  moves the balance rod  808  in accordance with a pressure of carbonated water at the other side of the static pressure hole  802 . 
     A bellows  810  having elasticity is disposed over the static pressure hole  802 . The first regulator elastic member  806   a  is disposed over the bellows  810  while being in contact with the bellows  810 . Beneath the static pressure hole  802 , the opening/closing member  804  and the second regulator elastic member  806   b  are disposed. As described above, the opening/closing member  804  functions to open or close at least a portion of the static pressure hole  802  in accordance with extension or retraction movement thereof. The second regulator elastic member  806   b  is provided at the body of the opening/closing member  804 , to move the opening/closing member  804  in an extension or retraction direction. 
     The bellows  810  is coupled with the regulator body  801   b  while extending in a direction perpendicular to the longitudinal direction of the first regulator elastic member  806   a . The bellows  801  prevents carbonated water from flowing toward the first regulator elastic member  806   a  while transmitting the pressure of carbonated water to the first regulator elastic member  806   a.    
     The balance rod  808  contacts the bellows  810  at one end thereof while contacting the end of the opening/closing member  804  at the other end thereof. The balance rod  808  extends through a hollow portion of the static pressure hole  802 . 
     Through the above-described configuration, carbonated water is introduced through the inlet of the carbonated water regulator  800 , passes along the opening/closing member  804 , and then contacts the bellows  810  after passing through the static pressure hole  802  and, as such, has influence on the bellows  810 . Thereafter, the carbonated water is discharged through the outlet of the carbonated water regulator  800 . 
     When the configuration of the carbonated water regulator  800  is viewed from a different standpoint, the carbonated water regulator  800  includes a first space  820  defined within the regulator body  801  by an inner surface of the regulator body  801  and the bellows  810  which has elasticity, a second space  822  partitioned from the first space  820  by the bellows  810 , and a third space  824  partitioned from the second space  822  by the static pressure hole  802 . 
     The first space  820  is provided with the first regulator elastic member  806   a  disposed within the first space  820 . The first space  820  is divided from the second space  822  by the bellows  810 , which has elasticity. 
     The second space  822  communicates with the carbonated water outlet  814 , form which carbonated water is discharged. The second space  822  is divided from the third space  824  at opposite sides of the static pressure hole  802 . 
     The third space  824  communicates with the carbonated water inlet  812 , into which carbonated water is introduced. The third space  824  is provided with the second regulator elastic member  806   b  and opening/closing member  804 . 
     Hereinafter, operation of the carbonated water regulator  800  having the above-described configuration will be described. 
     Carbonated water produced in the carbonated water tank  110  is forcibly discharged into the carbonated water discharge line  230  by the pressure of high-pressure carbon dioxide gas within the carbonated water tank  110 . 
     Carbonated water discharged from the carbonated water tank  110  under high pressure is introduced into the carbonated water regulator  800  through the carbonated water inlet  812  of the carbonated water regulator  800 . 
     The high-pressure carbonated water is then introduced into the second space  822  through the static pressure hole  802  after passing through the third space  824 . During this procedure, the high-pressure carbonated water has influence on the end of the opening/closing member  804  and, as such, has influence on the bellows  810 . 
     Thereafter, the carbonated water is discharged from the second space  822  through the carbonated water outlet  814 . 
     Force generated when carbonated water passes through the carbonated water regulator  800  may be divided into 1) a force F 1  to push the bellows  810  by the first regulator elastic member  806   a,  2) a force F 2  to push the opening/closing member  804  by the second regulator elastic member  806   b,  3) a force F 3  to push the bellows  810  by carbonated water, and 4) a force F 4  to push the end of the opening/closing member  804  by carbonated water. As the force F 1  is equal to the sum of the forces F 2  to F 4 , the discharge pressure of the carbonated water is reduced and, as such, carbonated water is discharged from the carbonated water regulator  800  at a predetermined pressure. 
       FIG. 10A  is a perspective view illustrating a carbonated water tank and a holding unit according to an embodiment.  FIG. 10B  is an exploded perspective view of the carbonated water tank and holding unit according to the illustrated embodiment.  FIG. 100  is a perspective view illustrating a bottom of the holding unit. 
     The refrigerator according to the illustrated embodiment includes a body, a carbonated water tank  110  to produce carbonated water through mixing of clean water with carbon dioxide gas, a sensor unit  115  inserted, at least a portion thereof, into the carbonated water tank  110 , to sense an internal state of the carbonated water tank  110 , and a holding unit  850  disposed at one side of the carbonated water tank  110  while holding the sensor unit  115  in a fixed state. 
     The carbonated water tank  110  is configured to store high-pressure carbon dioxide gas and high-pressure carbonated water. The carbonated water tank  110  is formed to have a cylindrical shape, using a stainless steel material, taking into consideration an internal pressure exerting in the carbonated water tank  110 . The sensor unit  115  is provided to measure a state of the carbonated water tank  110  including, for example, internal temperature and water level. 
     The sensor unit  115  is provided such that at least a portion thereof is inserted into the carbonated water tank  110 . The carbonated water tank  110  is provided with a tank hole  110   a  to receive at least a portion of the sensor unit  115 . 
     The holding unit  850  is disposed at one side of the carbonated water tank  110 , to hold the sensor unit  115 . The holding unit  850  may have various configurations, so long as it holds the sensor unit  115  while being supported by the carbonated water tank  110 . In the illustrated embodiment, the holding unit  850  has a cover shape to enclose the tank hole  110   a  of the carbonated water tank  110 . 
     In detail, the carbonated tank  110  is disposed in the first upper accommodation space while being seated on a first module support  145   a  ( FIG. 11A ). The tank hole  110   a  is provided at a top portion of the carbonated water tank  110 . The holding unit  850  which has a cover shape is disposed over the carbonated water tank  110 , to cover a portion of the carbonated water tank  110 . The sensor unit  115  and fitting tubes are coupled to the holding unit  850  and, as such, the carbonated water tank  110  may be coupled with the sensor unit  115  and fitting tubes in accordance with coupling of the holding unit  850  to the carbonated water tank  110 . 
     The holding unit  850  includes a holding plate  850   a , to which the sensor unit  115  is fixed, and a plate support  850   b  extending from a peripheral portion of the holding plate  850   a  in a bent state, to enable the holding unit  850  to be supported by the carbonated water tank  110 . 
     Holding plate holes  854  are provided at the holding plate  850   a  in order to hold the sensor unit  115 . Threads are formed at the holding plate holes  854 , to be threadedly coupled with threads formed at the sensor unit  115 . Seats may also be provided at the holding plate  850   a , to allow the sensor unit  115  to be seated on the holding plate  850   a.    
     The holding plate holes  854  formed at the holding plate  850   a  include tube holes, in which fitting tubes  864  may be fitted, and coupling holes  854   a  to be coupled with coupling rods  110   c  provided at the carbonated water tank  110 , respectively. 
     As described above, the plate support  850   b  extends from the peripheral portion of the holding plate  850   a  in a bent state. An end of the plate support  850   b  is mounted to a portion of the carbonated water tank  110 . The holding plate  850   a  is spaced apart from a portion of the carbonated water tank  110  by the plate support  850   b  by a certain distance. 
     As described above, the holding unit  850  is coupled to the carbonated water tank  110  by the plate support  850   b . In addition, the carbonated water tank  110  is provided with coupling rods  110   c  protruded from the top portion of the carbonated water tank  110  while being formed with threads at an upper end portion thereof, to have a bolt shape. Coupling holes  854   a  are also provided at the holding unit  850 . Accordingly, it may be possible to firmly fix the holding unit  850  to the carbonated water tank  110  by extending the coupling rods  110   c  through respective coupling holes  854   a , and then fastening nuts to respective coupling rods  110   c.    
     A certain space is provided between the carbonated water tank  110  and the holding plate  850   a  of the holding unit  850 . A gasket  860  is fitted in the space between the carbonated water tank  110  and the holding plate  850   a  of the holding unit  850 , to prevent leakage of carbonated water or clean water from the carbonated water tank  110 . 
     The gasket  860  is made of an elastic material. The gasket  860  is provided with gasket holes  860   a  to allow the sensor unit  115  and coupling rods  110   c  to extend therethrough. The gasket  860  contacts the carbonated water tank  110 . In an embodiment of the present invention, the gasket  860  is made of a silicon material. 
     For coupling of the sensor unit  115  and tubes to feed carbon dioxide gas, clean water, and carbonated water, the holding plate  850   a  of the holding unit  850  is provided with seats for the sensor unit  115  and fitting tubes  864 , in addition to the holding plate holes  854 . 
     The sensor unit  115  includes a water level sensor  111  to sense the level of water in the carbonated water tank  110 , a relief sensor to control an excessive pressure, and a temperature sensor  112  to sense the temperature of carbonated water in the carbonated water tank  110 . 
     The water level sensor  111  is provided with a sensor flange  111   a  to be seated on the top portion of the holding unit  850 . In addition, a concave sensor seat  862  is provided at an upper surface of the holding plate  850   a , to allow the sensor flange  111   a  to be seated thereon. 
     As the sensor flange  111   a  formed at one end of the water level sensor  111  is seated on and coupled to the holding unit  850 , the water level sensor  111  is fixedly mounted to the holding unit  850 . Water level sensing rods  111   b  are provided at the other end of the water level sensor  111 . The water level sensing rods  111   b  extend through the carbonated water tank  110 . The water level sensing rods  111   b  include a ground rod  111   ba  to set a reference for sensing of water level, a low water level sensing rod  111   bb  having a long length, to approach a bottom of the carbonated water tank  110  so as to sense a low water level, and a high water level sensing rod  111  be having a shorter length than the low water level sensing rod  111   bb , to approach a top of the carbonated water tank  110  so as to sense a high water level. 
     The carbonated water tank  110  may be configured to communicate with the clean water supply line  210 , clean water discharge line  220 , carbonated water discharge line  230 , and carbon dioxide gas supply line  200 , for introduction and discharge of clean water, carbon dioxide gas, and carbonated water. 
     The above-described lines may be directly coupled to the carbonated water tank  110 . In the illustrated embodiment, however, the lines may be coupled to respective fitting tubes  864  provided at the holding unit  850 , taking into consideration environments such as pressure, and, as such, may be firmly connected to the carbonated water tank  110 . 
     Each fitting tube  864  is fixed, at one end thereof, to the holding unit  850 , and is connected, at the other end thereof, to an associated one of the lines. A passage is formed through the fitting tube  864 , to allow clean water, carbon dioxide gas, or carbonated water to pass therethrough. 
     As described above, one end of each fitting tube  864  is coupled to the holding unit  850 . For this coupling, the carbonated water tank  110  is provided with a tube-shaped line guide  110   b  having a hollow portion while being protruded from the carbonated water tank  110  at a position corresponding to each fitting tube  864 . An end of the line guide  110   b  contacts the holding unit  850 , to be connected with the fitting tube  864 . 
     A carbon dioxide gas nozzle  866  is provided at the holding plate  850   a . Carbon dioxide gas from the carbon dioxide gas cylinder  120  is introduced into the carbon dioxide gas nozzle  866 . An end of the carbon dioxide gas nozzle  866  may be inserted into the carbonated water tank  110  and, as such, may directly inject carbon dioxide gas into the carbonated water tank  110 . 
     A lattice-shaped reinforcement member  856  may be provided at a lower surface of the holding plate  850   a , in order to enable the holding plate  850   a  to sufficiently endure high pressure of carbon dioxide gas and carbonated water. The reinforcement member  856  may include a plurality of longitudinal and lateral ribs spaced apart from one another by a uniform distance. In accordance with this structure, it may be possible to enhance strength of the holding unit  850 . 
     As described above, the holding plate holes  854  are provide at the holding plate  850   a , for holding the sensor unit  115 . Unit guides  852  are provided at the lower surface of the holding plate  850   a , to guide the sensor unit  115  extending through the holding plate holes  854 . 
     In detail, the unit guides  852  are provided at the reinforcement member  856  on the lower surface of the holding plate  850   a . Each unit guide  852  has a cylindrical structure extending downward while having a hollow portion. Through such a configuration, accordingly, the sensor unit  115  and lines may be more stably held by the holding unit  850 . 
     Hereinafter, coupling of the holding unit  850  and carbonated water tank  110  according to the above-described configurations will be described. 
     The sensor unit  115  and fitting tubes  863  are firmly held by the holding unit  850 . Holding of the sensor unit  115  and fitting tubes  864  may be achieved by bring flanges of the sensor unit  115  and fitting tubes  864  into contact with the holding plate  850   a  of the holding unit  850 , and then threadedly fastening the sensor unit  115  and fitting tubes  864  to the holding plate  850   a . Since threads are formed at the sensor unit  115  and fitting tubes  864 , they may be coupled with threads provided at the holding plate holes  854  of the holding unit  850 . Through such coupling, the holding unit  850 , sensor unit  115 , and lines may be integrated. 
     It may be possible to insert at least a portion of the sensor unit  115  into the carbonated water tank  110 , and to connect the fitting tubes  864  to the carbonated water tank  110  by coupling the sensor unit  115  and fitting tube  864  to the holding unit  850 , and then coupling the holding unit  850  to the top portion of the carbonated water tank  110 . 
     Through the above-described configuration, it may be possible to firmly couple the sensor unit  115  and lines to the carbonated water tank  110 , which has high internal pressure due to carbon dioxide gas and carbonated water. 
       FIG. 11A  is a perspective view illustrating arrangement of the water leakage sensor according to an embodiment.  FIG. 11B  is a cross-sectional view taking along the line A-A′ of  FIG. 11A .  FIG. 11C  is a view illustrating coupling of the water leakage sensor according to the illustrated embodiment.  FIG. 11D  is a view illustrating operation of the water leakage sensor according to the illustrated embodiment. In the following description, constituent elements identical to those of the above-described embodiments will be designated by the same reference numerals, respectively, and no description thereof will be given. 
     In accordance with an embodiment, the refrigerator includes a body, a storage chamber defined in the body while having an opened front side, a door to open or close the opened front side of the storage chamber, and a water tank to store clean water. The refrigerator also includes a carbon dioxide gas cylinder  120  storing carbon dioxide gas, a carbonated water tank  110  to produce carbonated water through mixing of clean water with carbon dioxide gas, a carbonated water production module having a module support  145  to support a bottom of the carbonated water tank  110  while being mounted to a back surface of the door, and a water leakage sensor  900  provided at the module support  145 , to sense water leakage occurring at the carbonated water production module. 
     The carbonated water production module includes a module case  140  including a lower accommodation space  153  to receive the carbon dioxide gas cylinder  120 , a first upper accommodation space  151  to receive the carbonated water tank  110 , and a second upper accommodation space  152  to receive a valve assembly  130 . 
     The carbonated water production module also includes an upper module  105 . The upper module  105  includes a first upper module  105   a  having the first upper accommodation space  151 , and a second upper module  105   b  having the second upper accommodation space  152 . 
     The module support  145  partitions the upper accommodation spaces  151  and  152  from the lower accommodation space  153  in the module case  140 . The module support  145  is configured to close or seal lower portions of the upper accommodation spaces  151  and  152  in order to allow water leaked from the carbonated water tank  110  or valve assembly  130  to be accumulated in the upper accommodation spaces  151  and  152 . 
     The module support  145  includes a first module support  145   a  to support a bottom of the first upper accommodation space  151 , in which the carbonated water tank  110  is accommodated, and a second module support  145   b  to support a bottom of the second upper accommodation space  152 , in which the valve assembly  130  is accommodated. 
     The module support  145  also includes a module support bottom portion  146   a  to form a bottom of the module support  145 , and a module support guide portion  146   b  extending upward from a peripheral edge of the module support bottom portion  146   a  in a bent state. 
     The bottom support  155  and guide  156  may be formed on the module support bottom portion  146   a . As described above, the carbonated water tank  110  is seated on the bottom support  155 . The guide  156  extends upward from the peripheral portion of the bottom support  155  in a bent state. 
     The water leakage sensor  900  is disposed on the module support bottom portion  146   a , to sense water leakage occurring in configurations disposed on the module support  145 , for example, the carbonated water tank  110 , the lines to guide carbonated water and clean water, and the valve assembly  130 . 
     The module support bottom portion  146   a  has an inclined surface at least a part thereof, and includes a first section disposed at one side of the inclined surface, namely, a lower side of the inclined surface, and a second section disposed at the other side of the inclined surface, namely, a higher side of the inclined surface, such that the second section is disposed at a higher level than the first section. The water leakage sensor is disposed on the first section of the module support bottom portion  146   a.    
     The module support bottom portion  146   a  may be inclined such that one side of the module support bottom portion  146   a  toward the door is higher than the other side of the module support bottom portion  146   a . In this case, the water leakage sensor  900  may be disposed on the other side of the module support bottom portion  146   a . Accordingly, when water leakage occurs, leaked water is collected on the module support bottom portion  146   a  even if the amount of leaked water is little. In this case, since the water leakage sensor  900  is disposed at the lower side of the module support bottom portion  146   a , namely, the other side of the module support bottom portion  146   a , it may be possible to more rapidly sense water leakage. 
     The water leakage sensor  900  includes a sensor housing  902 , and a plurality of terminals  904   a  and  904   b.    
     The sensor housing  902  defines an appearance of the water leakage sensor  900 , and is opened at least one side thereof. In the illustrated embodiment, the sensor housing  902  is opened at one side thereof, to receive leaked clean water or carbonated water. 
     The sensor housing  902  is seated on a sensor seat  908  provided at the module support bottom portion  146   a . The sensor seat  908  is shaped to protrude upward from the module support bottom portion  146   a  in order to enclose a peripheral portion of the sensor housing  902 . 
     The terminals  904   a  and  904   b  are disposed in the sensor housing  902 , to sense leakage of water and then to convert the sensed results into an electrical signal. In order to prevent trace amounts of water formed during use of the refrigerator due to moisture or the like from being erroneously sensed as water leakage, the terminals  904   a  and  904   b  are upwardly spaced apart from the bottom of the module support  145  by a predetermined height H. The predetermined height H is higher than a level of trace amounts of water accumulated after being formed during use of the refrigerator due to moisture or the like. The first height H may be varied in accordance with use environment and setting. 
     The terminals  904   a  and  904   b  are partitioned from each other by a sensor partition plate  906  disposed between the terminals  904   a  and  904   b  and, as such, are prevented from electrically contacting each other. In the illustrated embodiment, two terminals, namely, the first terminal  904   a  and the second terminal  904   b , are partitioned from each other by the sensor partition plate  906 . 
     In the illustrated embodiment, the plurality of terminals  904   a  and  904   b  include the first terminal  904   a , which is connected to an electrical ground, and the second terminal  904   b , which is connected to a voltage source. 
     The second terminal  904   b  is connected to a detecting unit  905  while being connected to the voltage source. In the illustrated embodiment, the voltage source is a 5V voltage source, and is connected to the detecting unit  905  and second terminal  904   b.    
     When there is no water leakage, current constantly flows through a circuit between the voltage source and the detecting unit  905 . However, when water leakage occurs, current flowing to the detecting unit  905  is varied in amount because the first and second terminals  904   a  and  904   b  are electrically connected by leaked clean water or carbonated water. In this case, a control unit (not shown) senses the current amount variation, and then displays occurrence of water leakage on the display provided at the front side of the door  21  or  22 . 
     The water leakage sensor  900  is electrically connected to the control unit (not shown). Accordingly, when the water leakage sensor  900  senses leakage of water, the control unit closes the valve assembly  130  and each valve, which are electrically connected to the control unit, to close lines of clean water, carbonated water, and carbon dioxide gas. In this case, accordingly, it may be possible to prevent further production of carbonated water, for safety. 
     Hereinafter, operation of the water leakage sensor  900  having the above-described configuration will be described. 
     When there is no water leakage, the amount of current flowing from the voltage source of the water leakage sensor  900  to the detecting unit  905  is constant. 
     When water leakage occurs at the carbonated water tank  110 , the line of carbonated water or clean water, or the valve installed at the line, leaked water drops onto the inclined module support bottom portion  146   a , and then moves to a lower place on the module support bottom portion  146   a  along the module support bottom portion  146   a . As a result, leaked clean water or carbonated water is introduced into the opened side of the water leakage sensor  900  positioned at the lower place of the inclined module support bottom portion  146   a , thereby causing the first and second terminals  904   a  and  904   b  to be electrically connected. 
     In this case, current which has constantly flowed from the voltage source to the water leakage sensor  905  is varied in amount due to current flowing to the first terminal  904   a  via the second terminal  904   b  because the second terminal  904   b  is electrically connected with the electrical ground, namely, the first terminal  904   a.    
     Current variation is sensed by the control unit (not shown) which, in turn, closes the lines of carbon dioxide gas, clean water, and carbonated water while stopping production of carbonated water. 
     The control unit (not shown) also informs occurrence of water leakage through the display provided at the front side of the door. Thus, it may be possible to inform whether failure has occurred, thereby preventing property damage caused by water leakage. 
       FIG. 12A  is a perspective view illustrating an arrangement of the relief valve according to an embodiment.  FIG. 12B  is a sectional view illustrating a coupled state of the relief valve according to the illustrated embodiment.  FIG. 12C  is a view illustrating operation of the relief valve according to the illustrated embodiment. In the following description, constituent elements identical to those of the above-described embodiments will be designated by the same reference numerals, respectively, and no description thereof will be given. 
     In accordance with an embodiment, the refrigerator includes a body, a storage chamber defined in the body while having an opened front side, a door to open or close the opened front side of the storage chamber, a water tank to store clean water, and a carbonated water production module provided at a back surface of the door, to produce carbonated water. The carbonated water production module includes a carbon dioxide gas cylinder  120  storing high-pressure carbon dioxide gas, a carbonated water tank  110  to produce carbonated water through mixing of clean water with carbon dioxide gas, and a relief valve  950  provided to be opened or closed, based on a predetermined pressure, and thus to prevent the carbonated water tank  110  from being excessively pressurized. 
     The relief valve  950  may be directly coupled to the carbonated water tank  110 . In an embodiment of the present invention, however, the relief valve  950  is coupled to a holding unit  850 , to which a sensor unit  115  including various sensors and lines is coupled. 
     The holding unit  850  includes a relief valve guide hole  870   a  formed with threads at an inner surface thereof. 
     The relief valve  950  includes a relief valve coupling portion  960  formed, at an outer peripheral surface thereof, with threads to be threadedly coupled with the relief valve guide hole  870   a.    
     The relief valve  950  may have various configurations, so long as it may be firmly coupled to the holding unit  850 . Through the above-described configuration, coupling of the relief valve  950  may be achieved by directly coupling the relief valve coupling portion  960  of the relief valve  950  to the relief valve guide hole  870   a  of the holding unit  850 . 
     A relief valve guide  870  is provided at a lower surface of a holding plate  850   a  included in the holding unit  850 , to guide the relief valve  950 . The relief valve guide  870  is provided at a holding plate reinforcement member  856  formed on the lower surface of the holding plate  850   a . The relief valve guide  870  has a hollow structure including a relief valve guide hole  870   a  while extending downward. When the holding unit  850  is coupled to the carbonated water tank  110 , at least a portion of the relief valve guide  870  or relief valve  950  is inserted into the carbonated water tank  110  and, as such, the relief valve  950  is more stably fixed to the holding unit  850 . 
     The relief valve  950  includes a relief valve body  952 , and a valve opening/closing unit  954  to move selectively through the relief valve body  952  in an extension or retraction direction. 
     The relief valve body  952  defines an appearance of the relief valve  950 . The relief valve body  952  is formed with a passage  970   a  extending between opposite sides of the relief valve body  952 , to allow carbon dioxide gas to pass there through. The relief valve body  952  has a cylindrical outer structure. In an embodiment of the present invention, the relief valve body  952  has an axially elongated nut shape. 
     The valve opening/closing unit  954  is provided at the passage  970   a , to selectively allow high-pressure carbon dioxide gas to pass through the passage  970   a.    
     The valve opening/closing unit  954  includes a valve elastic member  956  fixed, at one end thereof, while being movable at the other end thereof in an extension or retraction direction. The valve opening/closing unit  954  also includes a relief plate  958  provided at the other end of the valve elastic member  956 , to compress the valve elastic member  956  when the internal pressure of the carbonated water tank  110  is equal to or higher than a predetermined pressure, in order to open the passage  970   a.    
     The valve elastic member  956  always pushes the relief plate  958  such that the relief plate  958  is prevented from being spaced apart from the passage  970   a  when the internal pressure of the carbonated water tank  110  is below the predetermined pressure. 
     In a normal state, the relief plate  958  blocks the passage  970   a  at one side thereof. In this case, the other side of the relief plate  958  is supported by the valve elastic member  956 , to be prevented from being spaced apart from the passage  970   a.    
     The relief valve  950  includes the passage  970   a  extending between opposite sides of the relief valve body  952 , and an opening/closing space  970   b  provided at the passage  970   a  in the relief valve body  952  while having a greater diameter than the passage  970   a . In the opening/closing space  970   b , the valve elastic member  956  and relief plate  958  are disposed. 
     The passage  970   a  communicates with a hollow portion of the relief valve guide  870 , to receive high-pressure carbon dioxide gas from the carbonated water tank  110 . The passage  970   a  guides the received high-pressure carbon dioxide gas, to allow the high-pressure carbon dioxide gas to be outwardly discharged from the carbonated water tank  110 . The opening/closing space  970   b  is a space formed at the passage  970   a , to accommodate the valve opening/closing unit  954  to selectively open the passage  970   a.    
     High-pressure carbon dioxide gas introduced into the passage  970   a  of the relief valve  950  at one side of the passage  970   a  is discharged from the passage  970   a  through the other side of the passage  970   a . A sound absorber  962  is provided at the other side of the passage  970   a , to reduce noise generated during injection of high-pressure carbon dioxide gas. 
     Carbon dioxide gas emerging from the relief valve  950  is injected into the carbonated water production module. 
     Hereinafter, operation of the relief valve  950  having the above-described configuration will be described. 
     High-pressure carbon dioxide gas from the carbon dioxide gas cylinder  120  is introduced into the carbonated water tank  110 . The pressure of carbon dioxide gas in the carbon dioxide gas cylinder  120  is 45 to 60 bars. Such high-pressure carbon dioxide gas is introduced into the carbonated water tank  110  under the condition that the pressure of the carbon dioxide gas is reduced to 10 bars or below by the gas regulator  201 . Carbon dioxide gas is mixed with clean water in the carbonated water tank  110 , thereby producing carbonated water. The produced carbonated water is discharged into the dispensation space by the high pressure of carbon dioxide gas in the carbonated water tank  110 . 
     When the pressure of carbon dioxide gas in the carbonated water tank  110  exceeds 10 bars, the carbonated water tank  110  may be damaged. In this case, accordingly, the relief valve  950  operates. 
     In detail, the pressure of the carbonated water tank  110  always pushes the relief plate  958  disposed at the passage  970   a  of the relief valve  950 . When the internal pressure of the carbonated water tank  110  is equal to or greater than a first pressure, namely, 10 bars, the force to push the relief plate  958  at one side of the relief plate  958  by high-pressure carbon dioxide gas in the carbonated water tank  110  is greater than the force to push the relief plate  958  at the other side of the relief plate  958  by the valve elastic member  956 . In this case, accordingly, the valve elastic member  956  is compressed and, as such, the relief plate  958  no longer blocks the passage  970   a . As a result, the passage  970   a  is opened and, as such, carbon dioxide gas is outwardly discharged from the carbonated water tank  110  through the passage  970   a.    
     When it is assumed that, as forces acting on the relief plate  958 , there are a first force to push the relief plate  958  by high-pressure carbon dioxide gas in the carbonated water tank  110  and a second force to push the relief plate  958  by the valve elastic member  956  in the relief valve  950 , the passage  970   a  is opened, starting from the time when the first force is greater than the second force and, as such, high-pressure carbon dioxide gas is discharged. When the pressure of carbon dioxide gas in the carbonated water tank  110  is reduced to the first pressure or below, that is, when the second force is greater than the first force, the passage  970   a  is again blocked by the relief plate  958 . In this case, high-pressure carbon dioxide gas is no longer outwardly discharged from the carbonated water tank  110 . 
     As apparent from the above description, the refrigerator which is equipped with a carbonated water production apparatus according to an aspect of the present disclosure is configured to achieve strong coupling exhibiting high resistance to pressure while achieving an enhancement in work efficiency when a sensor and lines are coupled to a carbonated water tank. 
     Although a few embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.