Abstract:
A water softening apparatus having an improved structure to provide a function of an air brake, a dishwasher including the same and a control method thereof, the water softening apparatus having an air brake assembly and a regeneration tank and configured to soften wash water being supplied from a tub, wherein the air brake assembly including a water supply valve allowing wash water to be introduced therethrough, an ion exchange tank to accommodate an ion exchange resin therein, and a plurality of valves installed on a first path allowing wash water being introduced through the water supply valve to flow toward the ion exchange tank, wherein the regeneration tank is connected to the air brake assembly and accommodates regeneration material configured to purify the ion exchange resin.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2013-0108593, filed on Sep. 10, 2013, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Embodiments of the present disclosure relate to a water softening apparatus, a dishwasher having the same and a control method thereof, and more particularly, to a water softening apparatus having an improved structure capable of enhancing the water softening efficiency, a dishwasher having the same and a control method thereof. 
         [0004]    2. Description of the Related Art 
         [0005]    A dishwasher represents an apparatus to clean dishware by spraying high pressure wash water toward the dishware, and in general, the dishwasher performs a preliminary washing stage, a main washing stage, a rinsing stage and a drying stage. In the preliminary washing stage, dirt of dishware is removed by spraying wash water without detergent, and in the main washing stage, a washing of the dishware is achieved by allowing detergent to be introduced by a detergent supply apparatus while spraying wash water. 
         [0006]    The dishwasher includes a body provided at an inner side thereof with a washing tub, a basket reciprocatingly installed at an inside the washing tub and containing dishware, and a spray nozzle provided at an upper side and a lower side of the basket to spray wash water, so that the dishware is washed by the wash water sprayed by the spray nozzle. 
         [0007]    Meanwhile, the dishwasher may adopt a water softening apparatus using an ion exchange resin to soften hard water. Hard water having a great amount of metal cations, such as calcium and magnesium, interfere with the action of soap or detergent, degrading the washing performance of the dishwasher. 
         [0008]    The water softening apparatus is an apparatus for softening hard water by removing metal ions contained in the hard water, and includes an ion exchange resin tank to convert wash water into soft water and a regeneration tank to regenerate the ion exchange resin. 
         [0009]    In addition, an air brake include a water supply port allowing a source water to be introduced therethrough, an ion exchange resin tank connection port connecting such that wash water introduced through the water supply port is introduced into the ion exchange resin tank and a regeneration tank connection port connecting such that wash water is introduced into the regeneration tank. 
         [0010]    Although each of the water softening apparatus and the air brake may perform a different function, there is an increasing demand of a water softening apparatus having the function of an air brake as well as a dishwasher including such a water softening apparatus in terms of the convenience of consumer and optimization of system configuration. 
         [0011]    An air brake assembly of a dishwasher is disclosed in Korean Patent Application Publication No. 10-2006-0095838 as a relevant prior art. 
       SUMMARY 
       [0012]    Therefore, it is an aspect to provide a water softening apparatus having an improved structure to provide an air brake function , a dishwater including the same and a control method thereof. 
         [0013]    It is an aspect to provide a water softening apparatus having an improved structure by which an air brake function is provided, the configuration of the water softening apparatus is simplified configuration, and a simple algorithm of use is provided, a dishwasher including the same, and a control method thereof. 
         [0014]    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 disclosure. 
         [0015]    In accordance with an aspect, a water softening apparatus having an air brake assembly and a regeneration tank and configured to soften wash water being supplied from a tub, wherein the air brake assembly includes a water supply valve, an ion exchange tank and a plurality of valves. The water supply valve may allow wash water to be introduced therethrough. The ion exchange tank may accommodate an ion exchange resin therein. The plurality of valves may be installed on a first path allowing wash water being introduced through the water supply valve to flow toward the ion exchange tank. The regeneration tank may be connected to the air brake assembly and accommodate regeneration material configured to purify the ion exchange resin. 
         [0016]    A plurality of through holes may be formed on the first path. The plurality of through holes may be on/off controlled by the plurality of valves. 
         [0017]    The plurality of valves may be formed on the first path in a number and a position corresponding to a number and a position of the plurality of through holes. 
         [0018]    The water softening apparatus may further include a supply water storage tank. The supply water storage tank may be provided at an upper side of the ion exchange tank and configured to store wash water being introduced through the water supply valve. The plurality of valves may include a first valve configured to control a flow of the wash water being introduced through the water supply valve toward the supply water storage tank, a second valve configured to control a flow of the wash water being introduced through the water supply valve toward the regeneration tank, and a third valve configured to control a flow of the wash water being introduced through the water supply valve toward the ion exchange tank. 
         [0019]    When the wash water is supplied to the ion exchange tank, the first valve and the second valve may be switched off, and the third valve may be switched on. 
         [0020]    When the wash water is supplied to the supply water storage tank, the first valve may be switched on, and the second valve and the third valve may be switched off. When the wash water stored in the supply water storage tank is discharged to the ion exchange tank, the first valve and the third valve may be switched on, and the second valve may be switched off. 
         [0021]    When the wash water is supplied to the regeneration tank, the first valve and the third valve may be switched off, and the second valve may be switched on. When the wash water stored in the regeneration tank is discharged to the ion exchange tank, the first valve may be switched off, and the second valve and the third valve may be switched on. 
         [0022]    The regeneration tank may include a path tube, at least one first flow path and at least one second flow path. The path tube may be connected to a protrusion formed on the second valve by a connecting member. The at least one first flow path may be formed along an edge of the regeneration tank so as to allow wash water being supplied to the path tube through the protrusion to flow thereathrough. The at least one second flow path may be formed along a bottom surface of the regeneration tank while diverged from the at least one first flow path so as to allow the wash water to flow therethrough. 
         [0023]    Regeneration water stored in the regeneration tank may be discharged through the path tube and supplied to the ion exchange tank through the protrusion. 
         [0024]    The regeneration tank may further include an opening/closing unit to open and close the regeneration tank to replenish the regeneration material, and an end portion of the at least one first flow path may be formed at a position equal to or higher than the opening/closing unit. 
         [0025]    The end portion of the at least one first flow path may be bent toward the bottom surface of the regeneration tank. 
         [0026]    One side surface of the second flow path facing the opening/closing unit may be provided with a partition wall unit and at least one bubble removing unit. The partition wall unit may have a slit shape such that wash water being introduced through the path tube flows toward the opening/closing unit. The at least one bubble removing unit may be provided lengthwise along the partition wall unit to remove bubbles contained in the wash water. 
         [0027]    The partition wall unit and the at least one bubble removing unit may be coupled to each other such that the one side surface of the second flow path is provided in a flat shape. 
         [0028]    The partition wall unit and the at least one bubble removing unit may be coupled to each other such that a step is formed on the one side surface of the second flow path. 
         [0029]    The at least one bubble removing unit may be coupled to the partition wall unit to form a step having an inclination of about 22.5 degrees or below. 
         [0030]    One of the at least one bubble removing unit may be coupled to the partition wall to form a step having an inclination of about 22.5 degrees or below toward one of the at least one first flow path. Another one of the at least one bubble removing unit may be coupled to the partition wall to form a step having an inclination of about 22.5 degrees or below toward another one of the at least one first flow path while facing the one of the at least one bubble removing unit. 
         [0031]    The first path may be located along one side of the ion exchange tank to which the plurality of valves are coupled. 
         [0032]    The air brake assembly may further include a second path allowing external air introduced through an inlet hole formed at one side of the air brake assembly to flow toward the tub after passing through a tub connecting hole. The tub connecting hole may be formed at one end portion of the second path. 
         [0033]    The inlet hole may be provided at a position equal to or lower than a half of a height of the air brake assembly. 
         [0034]    The second path may be connected to the tub connecting hole to prevent vapor discharged through the tub connecting hole during a washing operation from making contact with wash water stored in the supply water storage tank, the second path including at least one line forming a boundary with the supply water storage tank. 
         [0035]    A plurality of guides may be formed on at least one side surface of the second path to prevent vapor discharged through the tub connecting hole from flowing backward during a washing operation. 
         [0036]    The plurality of guides may include a plurality of first guides. The plurality of first guides may be formed on a portion of the second path corresponding to an upper surface of the supply water storage tank, and form a curved surface. The plurality of second guides may be formed on a portion of the second path corresponding to a lateral side surface of the supply water storage tank, and form a shape inclined toward the tub connecting hole. 
         [0037]    A plurality of ribs may be formed at an inside of the supply water storage tank to guide wash waster stored in the supply water storage tank to be discharged to the ion exchange tank. 
         [0038]    In accordance with an aspect, a dishwasher includes a tub, a door, a sump, an air brake assembly and a regeneration tank. The tub may be provided at an inside of a body of the dishwasher to wash dishes. The door may be installed at a front surface of the body so as to be open and close. The sump may be provided at a lower side of the tub to accommodate wash water. The air brake assembly may include an ion exchange tank accommodating an ion exchange resin therein and a plurality of valves installed at one side surface thereof, and a supply water storage tank located at an upper side of the ion exchange tank while integrally formed with the ion exchange tank. The regeneration tank may be connected to the ion exchange tank to regenerate the ion exchange resin and provided with a floating sensor unit installed therein to sense a water level of regeneration water accommodated therein and a density of regeneration material accommodated therein. The plurality of valves may be configured to be switched on/off and installed on a path allowing wash water being introduced through a water supply valve to flow toward the ion exchange tank therethrough. 
         [0039]    The air brake assembly may be provided at an outer circumference of the tub, and the regeneration tank may be provided at an inner circumference of the door so as to be connected to the air brake assembly by a connecting member. 
         [0040]    The regeneration tank may include an opening/closing unit to open and close the regeneration tank to replenish the regeneration material. A vent unit may be formed at an upper side of the opening/closing unit to allow air inside the tub to flow toward the generation tank. 
         [0041]    A tube installed along an outer circumference of the tub may be connected to the vent unit. One end portion of the tube may be mounted at an inside lower end of the tub. 
         [0042]    A blocking film may be installed on the vent unit to prevent foreign substance inside the tub from flowing to the regeneration tank. 
         [0043]    The blocking film may protrude toward the tub while coupled to the bent unit. 
         [0044]    The plurality of valves may include a first valve configured to control a flow of the wash water being introduced through the water supply valve toward the supply water storage tank, a second valve configured to control a flow of the wash water being introduced through the water supply valve toward the regeneration tank, and a third valve configured to control a flow of the wash water being introduced through the water supply valve toward the ion exchange tank. The plurality of valves may include a solenoid valve. 
         [0045]    The dishwasher may further include a control unit configured to control on/off of the first valve, the second valve and the third valve such that the wash water is introduced to an inside of the regeneration tank or discharged to the ion exchange tank based on the water level of the regeneration water and the density of regeneration material that are sensed by the floating sensor unit. 
         [0046]    The control unit may operate an alarming device informing a time for replenishing the regeneration material. 
         [0047]    The floating sensor unit may include a floating sensor and a float whose floating position varies with the water level of the regeneration water and the density of the regeneration material. The floating sensor may generate a sensing signal depending on a distance from the float. The float may include a floating body whose floating position varies with the water level of the regeneration water and the density of the regeneration material, and a magnet coupled to the floating body. 
         [0048]    An amount of the regeneration water required to regenerate the ion exchange resin may be about 140 ml or more and about 260 ml or less. 
         [0049]    In accordance with an aspect, a method of controlling a dishwasher having a water softening apparatus, the method including: checking a position of a floating body whose floating position varies with a water level of regeneration water and a density of regeneration material by use of a floating sensor; comparing the checked position of the floating body with a reference position of the floating body; if determined that the position of the floating body reaches to the reference position of the floating body, switching off a first valve and switching on a second valve and a third valve such that regeneration water inside a regeneration tank is discharged to an ion exchange tank; if determined that the position of the floating body does not reach to the reference position of the floating body, switching off the first valve and the third valve and switching on the second valve such that a reference value of a water level of the regeneration water is satisfied by generating the regeneration water from wash water introduced into the regeneration tank; checking the position of the floating body after a predetermined period of time; and determining whether a present point of time corresponds to a time for replenishing the regeneration material by comparing the checked position of the floating body with the reference position of the floating body. 
         [0050]    The reference position of the floating body may be a position satisfying the reference value of the water level of the regeneration water and a reference value of the density of the regeneration material. 
         [0051]    The method may further include informing the time for replenishing the regeneration material by controlling an alarming device if the present point of time corresponds to the time for replenishing regeneration material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0052]    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: 
           [0053]      FIG. 1  is a perspective view illustrating a dishwasher in accordance with an embodiment. 
           [0054]      FIG. 2  is a perspective view illustrating a coupling structure of an air brake assembly and a regeneration tank of the dishwasher in accordance with an embodiment. 
           [0055]      FIG. 3  is a perspective view illustrating a coupling structure of the air brake assembly and the regeneration tank of the dishwasher in accordance with an embodiment with some components of the dishwasher omitted. 
           [0056]      FIG. 4  is a drawing illustrating the air brake assembly of the dishwasher in accordance with an embodiment. 
           [0057]      FIG. 5  is a schematic view illustrating an operating state of a plurality of valves of the dishwasher in accordance with an embodiment. 
           [0058]      FIG. 6  is a drawing illustrating the regeneration tank of the dishwasher in accordance with an embodiment. 
           [0059]      FIG. 7  is a drawing illustrating a regeneration tank of a dishwasher in accordance with an embodiment. 
           [0060]      FIGS. 8A to 8D  are drawing a coupling structure of a partition wall unit and a bubble removing unit that are installed on the regeneration tank of  FIG. 7 . 
           [0061]      FIG. 9  is a drawing illustrating a regeneration tank of a dishwasher in accordance with an embodiment. 
           [0062]      FIG. 10  is a block diagram showing a process of a dishwasher being controlled by a floating sensor unit installed on the regeneration tank of  FIG. 9 . 
           [0063]      FIG. 11  is a flow chart showing an operating state of the floating sensor installed on the regeneration tank of  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION 
       [0064]    Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
         [0065]      FIG. 1  is a perspective view illustrating a dishwasher in accordance with an embodiment,  FIG. 2  is a perspective view illustrating a coupling structure of an air brake assembly and a regeneration tank of the dishwasher in accordance with an embodiment,  FIG. 3  is a perspective view illustrating a coupling structure of the air brake assembly and the regeneration tank of the dishwasher in accordance with an embodiment with some components of the dishwasher omitted,  FIG. 4  is a drawing illustrating the air brake assembly of the dishwasher in accordance with an embodiment, and  FIG. 5  is a schematic view illustrating an operating state of a plurality of valves of the dishwasher in accordance with an embodiment. 
         [0066]    Referring to  FIGS. 1 to 5 , a dishwasher  1  includes a body  2  provided with a tub  3  that forms an external appearance of the dishwasher  1  and in which dishware is washed. The body  2  is provided at a front surface thereof with an opening  4  formed to be open toward a front side such that dishware is inserted or withdrawn into/from the tub  3 . The body  2  is provided at the front surface thereof with a door  12  installed while hinged to a front lower portion of the body  2  to open and close the opening  4  while rotating. 
         [0067]    The body  2  is provided at the front surface thereof with a display unit  9  mounted to display an operating status of the dishwasher  1  and with a control unit  10  mounted to manipulate an operation of the dishwater  1 . 
         [0068]    One pair of baskets  5  provided with an accommodation unit having an upper surface thereof open to accommodate dishware are reciprocatingly installed at an upper side and a lower side of the tub  3  such that dishware is withdrawn and inserted through the front surface of the body  2  that is open. 
         [0069]    In addition, a plurality of spray nozzles  7  are rotatably installed at an upper side and a lower side of each of the two baskets  5  to wash the dishware contained in the baskets  5  while rotating to spray water through spray holes  7   a.  In this case, the basket  5  is formed by a wire  6  disposed in a lattice pattern such that water sprayed from the spray nozzle  7  reaches to the dishware accommodated inside the basket  5 . 
         [0070]    The tub  3  is provided at a lower portion thereof with a sump  8  formed to accommodate wash water, and with a water supply device including a water supply path (not shown) to flow wash water and a water supply valve (not shown) and a water drain device including a drain path (not shown) and a drain pump (not shown). 
         [0071]    The dishwasher  1  may include an air brake assembly  100  and regeneration tanks ( 200 :  200   a,    200   b ). The air brake assembly  100  may be installed at an outer circumferential surface of the tub  3 , and the regeneration tank  200  may be installed at an inner circumferential surface of the door  12 . The air brake assembly  100  is connected to the regeneration tank  200  through a connecting member  300 . The connecting member  300  includes a rubber hose. The air brake assembly  100  has a cover  110  facing an inner circumferential surface of the body  2 , and the regeneration tank  200  has a cover  210  facing an inside of the tub  3 . The cover  210  of the regeneration tank  200  is provided with an opening/closing unit  220  to open and close the regeneration tank  200 . 
         [0072]    The air brake assembly  110  includes a water supply valve  120 , an ion exchange tank  130 , a supply water storage tank  140  and a plurality of valves  150 ,  160  and  170 . 
         [0073]    An ion exchange resin is accommodated in the ion exchange tank  130  to remove heavy metal and metal ions contained in wash water being introduced through the water supply valve  120  by adsorption. The ion exchange resin serves to change wash water into soft water having a superior washing performance. A representative example of ion exchange resin may be implemented using R—SO 3 Na. Hard water is softened by use of an ion exchange resin through an equation below. 
         [0000]      2(R—SO 3 Na)+Ca 2+ →(R—SO 3 ) 2 Ca+2Na + 
 
         [0074]    The ion exchange tank  130  is provided at an inside of the air brake assembly  100  so as to be located at a lower side of the supply water storage tank  140 . The plurality of valves  150 ,  160  and  170  may be installed at one side surface of the ion exchange tank  130 . This will be described later in detail. 
         [0075]    The supply water storage tank  140  is provided at an inside of the air brake assembly  100  so as to be located at an upper side of the ion exchange tank  130 . Wash water being introduced through the water supply valve  120  is stored in the supply water storage tank  140  for a predetermined period of time, and thus the temperature of wash water (about 15° C.) becomes similar to the room temperature (about 23° C.). Accordingly, an additional energy consumption required to increase the temperature of wash water is reduced. 
         [0076]    A plurality of ribs  141  may be formed at an inside of the supply water storage tank  140 . The plurality of ribs  141  serve to guide wash water stored in the supply water storage tank  140  to be discharged toward the ion exchange tank  130  located at a lower side of the supply water storage tank  140 . One end portion of each of the plurality of ribs  141  may be provided in a form inclined toward the ion exchange tank  130 . 
         [0077]    The plurality of valves  150 ,  160  and  170  may be formed on a first path  180  allowing wash water introduced through the water supply valve  120  to flow toward the ion exchange tank  130  therethrough. The plurality of valves  150 ,  160  and  170  control an on/off of through holes  132 ,  142  and  202  formed through the first path  180 . The plurality of valves  150 ,  160  and  170  may be installed on the first path  180  in the number and position corresponding to the plurality of through holes  132 ,  142  and  202 . The first path  180  may be formed along one side surface of the ion exchange tank  130  to which the plurality of valves  150 ,  160  and  170  are coupled. 
         [0078]    Wash water introduced through the water supply valve  120  may be moved to one of the supply water storage tank  140 , the ion exchange tank  130  and the regeneration tank  200  through the plurality of through holes  132 ,  142  and  202 . In detail, the plurality of valves  150 ,  160  and  170  may include a first valve  140 , a second valve  160  and a third valve  170 . The first valve  150  controls wash water introduced through the water supply valve  120  toward the supply water storage tank  140  through the through hole  142 , the second valve  160  controls wash water introduced through the water supply valve  120  toward the regeneration tank  200  through the through hole  202 , and the third valve  170  controls wash water introduced through the water supply valve  120  toward the icon exchange tank  130  through the through hole  132 . 
         [0079]    The plurality of valves  150 ,  160  and  170  may include a solenoid valve. The plurality of valve  150 ,  160  and  170  may include a bobbin (referred to as a hollow cylinder around which a coil wire for an electric circuit is wound) and a plunger  152 . When an electricity flows through the bobbin  151 , the plunger  152  ascends so that paths  180 ,  181  and  182  communicating with the plurality of through holes  132 ,  142 , and  202  are open, and when an electricity is blocked from the bobbin  151 , the plunger  152  descends due to the weight of the plunger  152 , so that the paths  180 ,  181  and  182  communicating with the plurality of through holes  132 ,  142 , and  202  are closed. 
         [0080]    The through hole  132  toward the ion exchange tank  130  is formed on the first path  180 , and the through hole  142  toward the supply water storage tank  140  and the through hole  202  toward the regeneration tank  200  are formed on the paths  181  and  182  diverging from the first path  180 . 
         [0081]    An on-state of the plurality of valves  150 ,  160  and  170  represents a state in which the plunger  152  ascends, and an off-state of the plurality of valves  150 ,  160  and  170  represents a state in which the plunger  152  descends. 
         [0082]    When wash water introduced through the water supply valve  120  is supplied to the ion exchange tank  130 , the first valve  150  and the second valve  160  are in an off-state, and the third valve  170  is in an on-state. In this case, wash water introduced through the water supply valve  120  moves along the first path  180 , and via the through hole  132 , is supplied to the ion exchange tank  130 . A slit  183  is formed at one end portion of the first path  180 , and wash water flowing along the first path  180  is supplied to an ion exchange chamber  131  through the slit  183 . The wash water supplied to the inside of the ion exchange tank  130  is supplied to the sump  8  through a sump inlet hole  8   a.    
         [0083]    When wash water introduced through the water supply valve  120  is supplied to the supply water storage tank  140 , the first valve  150  is in an on state and the second valve  160  and the third valve  170  are in an off-state. In this case, wash water introduced through the water supply valve  120  moves to the supply water storage tank  140  along the path  181  via the through hole  132 . 
         [0084]    When wash water stored in the water supply storage tank  140  is discharged to the ion exchange tank  130 , the first valve  150  and the third valve  170  are in an on-state, and the second valve  160  is in an off-state. In this case, wash water stored in the supply water storage tank  140  is discharged to the ion exchange tank  130  along the path  181  and the first path  180 . 
         [0085]    When wash water introduced through the water supply valve  120  is supplied to the regeneration tank  200 , the first valve  150  and the third valve  170  are in an off-state, and the second valve  160  is in an on state. In this case, the wash water introduced through the water supply valve  120  is supplied to the regeneration tank  200  along the path  182  via the through hole  202 . 
         [0086]    When wash water stored in the regeneration tank  200  is discharged to the ion exchange tank  130 , the first valve  150  is in an off state, and the second valve  160  and the third valve  170  are in an on-state. In this case, wash water stored in the regeneration tank  200  is discharged to the ion exchange tank  130  along the path  182  and the first path  180 . 
         [0087]    The number of the plurality of valves  150 ,  160  and  170  is not limited to three, and the position of the plurality of valves  150 ,  160  and  170  is not limited to one side surface of the ion exchange tank  130 . 
         [0088]    A flow meter  184  may be formed on the first path  180  to sense a water level of wash water introduced through the supply water valve  120 . 
         [0089]    The air brake assembly  100  is provided with a second path  190  allowing external air to flow therethrough. The second path  190  may include an inlet hole  191  and a tub connecting hole  3   a.  In detail, external air introduced through the inlet hole  191  formed at one side surface of the air brake assembly  100  moves along the second path  190 , and through the tub connecting hole  3   a  formed at one end portion of the second path  190 , is supplied to the tub  3 . The tub connecting hole  3   a  communicates with the inside of the tub  3 . 
         [0090]    The inlet hole  191  allowing external air to be introduced therethough is formed at a position equal to or lower than a half of the height of the air brake assembly  100 . The nearer to a bottom surface of the air brake assembly  100  the inlet hole  191  is formed, the longer the length of the second path  190  is. 
         [0091]    A plurality of guides  192  and  193  may be formed on the second path  190 . The plurality of guides  192  and  193  may be installed on at least one side surface of the second path  190  to prevent vapor discharged through the tub connecting hole  3   a  from the tub  3  during a washing operation from flowing backward. The plurality of guides  192  and  193  may include a plurality of first guides  192  and a plurality of second guides  193 . The plurality of first guides  192  are formed on a portion of the second path  190  corresponding to an upper surface of the supply water storage tank  140 , and the plurality of second guides  193  are formed on a portion of the second path  190  corresponding to a lateral side surface of the supply water storage tank  140 . The plurality of first guides  192  may have a curved surface, and the plurality of second guides  193  may have a shape inclined toward the tub connecting hole  3   a.  The plurality of first guides  192  are formed at one side surface of the second path  190 , and the plurality of second guides  193  are formed at both side surfaces of the second path  190  so as to face each other. The shape and position of the plurality of first guides  192  and the plurality of second guides  193  are not limited thereto, and may vary as long as the plurality of guides  192  and  193  prevent vapor discharged through the tub connecting hole  3   a  from flowing backward. 
         [0092]    The second path  190  may include at least one line  194  to prevent vapor discharged through the tub connecting hole  3   a  from making contact with wash water stored in the supply water storage tank  140 . The at least one line  194  is connected to the tub connecting hole  3   a  so as to form a boundary with respect to the supply water storage tank  140 . The at least one line  194  may be located at an upper surface of the supply water storage tank  140 , but the position of the at least one line  194  is not limited thereto. The at least one line  194  may form one surface of the second path  190  forming the boundary with respect to the supply water storage tank  140 . The more the at least one line  194  is, the more difficult vapor discharged through the tub connecting hole  3   a  makes contact with the wash water stored in the supply water storage tank  140 . 
         [0093]    An air gap  185  is formed at one side of the first path  180  to prevent a siphone phenomenon from occurring when water supply is stopped. 
         [0094]    The air brake assembly  100  may further include a sump drain connecting port  8   b  connecting to the sump  8  to discharge wash water to the outside after the washing operation is finished, a drain hose connecting port  11  connecting to a drain hose (not shown) and a drain path  199  serving as a path of wash water being drained. 
         [0095]      FIG. 6  is a drawing illustrating the regeneration tank of the dishwasher in accordance with an embodiment, and  FIG. 7  is a drawing illustrating a regeneration tank of a dishwasher in accordance with an embodiment. 
         [0096]    Referring  FIGS. 6 and 7 , regeneration material is accommodated in the regeneration tank  200  to improve the water softening performance by regenerating the ion exchange resin. The regeneration material in the regeneration tank  200  may be implemented as salt NaCl. The ion exchange resin, after adsorbing metal ions contained in wash water, increases in the volume thereof, and thus the performance to adsorb metal ions is lowered. A process of the ion exchange resin removing metal ions is referred to as a regeneration by an ion exchange resin. The regeneration reaction of the ion exchange resin is achieved by an equation below, so that ions of the ion exchange resin being exhausted as the water softening reaction continues are restored. 
         [0000]      (R—SO 3 ) 2 Ca+2NaCl→2(R—SO 3 Na)+CaCl 2  
 
         [0097]    The amount of regeneration water required to regenerate the ion exchange resin is about 140 ml or more and about 260 ml or less. 
         [0098]    The regeneration tank  200  may include a path tube  230 , at least one first flow path  240  and at least one second flow path  250 . 
         [0099]    The path tube  230  is connected to a protrusion  161  located at a rear surface of the second valve  160  through the connecting member  300 . The protrusion  161  may be formed at an end portion of the path  182 . Regeneration water stored in the regeneration tank  200  is discharged from the path tube  230 , and after sequentially passing through the connecting member  300  and the protrusion  161 , is supplied to the ion exchange tank  130  along the first path  180 . On the contrary, wash water introduced through the supply water valve  120  is discharge from the protrusion  161 , and after sequentially passing through the connecting member  300  and the path tube  230 , is supplied to the regeneration tank  200 . That is, the path tube  230  corresponds to a water outtake part of regeneration water as well as a water intake part of wash water. 
         [0100]    The wash water introduced to the path tube  230  through the protrusion  161  moves along the at least one first flow path  240  formed along an edge of the regeneration tank  200 . The at least one first flow path  240  extends toward an upper side of the regeneration tank  200 , and an end portion of the at least one first flow path  240  extending toward an upper side of the regeneration tank  200  is bent toward a bottom surface  251  of the regeneration tank  200 . In addition, the end portion of the at least one first flow path  240  extending toward an upper side of the regeneration tank  200  may be located at a position equal to or higher than that of the opening/closing unit  220  provided at an upper side of the cover  210 . 
         [0101]    The second flow path  250  diverges from the at least one first flow path  240  so as to be formed along the bottom surface  251  of the regeneration tank  200  such that wash water introduced through the path tube  230  flows through the second flow path  250 . A partition wall unit  252  having a slit shape is formed at one side surface of the second flow path  250  facing the opening/closing unit  220 . The other side surface of the second flow path  250  corresponds to the bottom surface  251  of the regeneration tank  200 . The partition wall unit  252  having a slit shape allows regeneration material, for example, salt, accommodated in the regeneration tank  200  to have a uniform distribution. 
         [0102]    When the at least one first flow path  240  is provided along an edge of one side of the regeneration tank  200 , two paths  260   a  and  260   b  may be formed for distributing regeneration material solution in the regeneration tank  200 . When the at least one first flow path  240  is provided along edges of both sides of the regeneration tank  200 , three paths  260   a,    260   b  and  260   c  may be formed for distributing regeneration material solution in the regeneration tank  200 . If the at least one first flow path  240  is provided along edges of both sides of the regeneration tank  200 , and three paths  260   a,    260   b  and  260   c  are formed, the regeneration material solution is dispersed along the three paths  260   a,    260   b  and  260   c,  which reduces impact exerted on the partition wall  252  having a slit shape by wash water or regeneration material solution being introduced through the path tube  230 . 
         [0103]    The opening/closing unit  220  is provided at an upper side thereof with a vent unit  270  to allow air in the tub  3  to flow toward the regeneration tank  200 . 
         [0104]    A tube (not shown) installed along the outer circumferential surface of the tub  3  is connected to the vent unit  270 , and one end portion of the tube may be mounted at an inside lower end portion of the tub  3 . As the tube is connected to the vent unit  270 , air in the tub  3  moves toward the regeneration tank  200  along the tube. 
         [0105]    A blocking film (not shown) may be installed on the vent unit  270 . Since the blocking film is installed on the vent unit  270 , residue of food is prevented from being introduced to the regeneration tank  200 . 
         [0106]      FIGS. 8A to 8D  are drawing a coupling structure of a partition wall unit and a bubble removing unit that are installed on the regeneration tank of  FIG. 7 . 
         [0107]    Referring to  FIGS. 8A to 8D , the partition wall unit  252  and at least one bubble removing unit  253  may be formed at a portion of one side surface of the second flow path  250  facing the opening/closing unit  220 . Bubbles may be included in wash water introduced through the path tube  230 . The bubbles may block the partition wall unit  252  having a slit shape and prevent wash water from moving to an upper side of the regeneration tank  200 . In order to remove the bubbles, the at least one bubble removing unit  253  may be formed in a longitudinal direction of the partition unit  252 . 
         [0108]    The partition wall  252  and the at least one bubble removing unit  253  may correspond to the one side surface of the second flow path  250  facing the opening/closing unit  220 . 
         [0109]    The at least one bubble removing unit  253  may be coupled to a side surface of the partition wall unit  252  in a longitudinal direction of the partition wall unit  252  such that the one side surface of the second flow path  250  facing the opening/closing unit  220  is provided in a flat shape. 
         [0110]    In addition, the at least one bubble removing unit  253  may be coupled to a side surface of the partition wall unit  252  in a longitudinal direction of the partition wall unit  252  such that a step is formed on the one side surface of the second flow path  250  facing the opening/closing unit  220 . 
         [0111]    The step formed when the at least one bubble removing unit  253  is coupled to the partition wall unit  252  may have an inclination of about  22 . 5  degrees or below. 
         [0112]    When the at least one bubble removing unit  253  is provided in two units thereof, one bubble removing unit  253   a  of the at least one bubble removing units  253  is coupled to the side surface of the partition wall unit  252  to form a step having an inclination of about 22.5 degrees or below toward one of the at least one first flow path  240 , and another one bubble removing unit  253   b  of the at least one bubble removing unit  253  is coupled to the side surface of the partition wall  252  to form a step having an inclination of about 22.5 degrees or below toward another one of the at least one first flow path  240  while facing the one bubble removing unit  253   a  of the at least one bubble removing unit  253 . 
         [0113]    Bubbles included in the wash water may move to the upper side of the regeneration tank  200  through the at least one first flow path  240  formed at the edge of the regeneration tank  200  along an inner circumferential surface of the bubble removing unit  253 . 
         [0114]      FIG. 9  is a drawing illustrating a regeneration tank of a dishwasher in accordance with an embodiment, and  FIG. 10  is a block diagram showing a process of a dishwasher being controlled by a floating sensor unit installed on the regeneration tank of  FIG. 9 . 
         [0115]    Referring to  FIGS. 9 and 10 , a water level sensor unit  290  may be installed on a regeneration tank  200   b  to sense a water level of regeneration water and a density of regeneration material. 
         [0116]    The water level sensor unit  290  may include a floating sensor (not shown) and a float (not shown). The floating sensor generates a sensing signal depending on a distance from the float whose floating position varies with the water level of the regeneration water and the density of the regeneration material. 
         [0117]    The float may include a floating body (not shown) whose floating position varies with the water level of regeneration water and the density of regeneration material, and a magnet coupled to the floating body. 
         [0118]    The dishwasher  1  may further include a control unit  400  and an alarming device  500 . The control unit  400  may switch on/off the first valve  150 , the second valve  160  and the third valve  170  such that wash water is introduced into the regeneration tank  200  or regeneration water is discharged to the ion exchange tank  130  based on the water level of regeneration water and the density of regeneration material that are sensed by the floating sensor. 
         [0119]    In addition, the control unit  400  may operate the alarming device  500  to inform the time for replenishing regeneration material. 
         [0120]      FIG. 11  is a flow chart showing an operating state of the floating sensor installed on the regeneration tank of  FIG. 9 . 
         [0121]    Referring to  FIG. 11 , a control method of a dishwasher including a water softening device is as follows. 
         [0122]    The position of the floating body whose floating position varies with the water level of regeneration water and the density of regeneration material is checked, the checked position of the floating body is compared with a reference position of the floating body, and if determined that the checked position of the floating body reaches to the reference position of the floating body, the first valve is switched off and the second valve and the third valve are switched on such that regeneration water inside the regeneration tank is discharged to the ion exchange tank, and if determined that the checked position of the floating body does not reach to the reference position of the floating body, the first valve and the third valve are switched off and the second valve is switched on such that a reference value of a water level of the regeneration water is satisfied by generating the regeneration water from wash water introduced into the regeneration tank, and the position of the floating body is checked after a predetermined period of time. In this case, if determined that the checked position of the floating body reaches to the reference position of the floating body, the first valve is switched off and the second valve and the third valve are switched on such that regeneration water in the regeneration tank is discharged to the ion exchange tank, and if determined that the checked position of the floating body does not reach to the reference position of the floating body, the position of the floating body is checked using the floating sensor after a predetermined period of time to check whether the density of the regeneration material satisfies a reference value, the checked position of the floating body is compared with the reference position of the floating body to determine whether the current time corresponds to the time for replenishing regeneration material, and if determined that the floating body does not reach to the reference position of the floating body after the determination of the time for replenishing regeneration material, the first valve is switched off and the second valve and the third valve are switched on such that regeneration water in the regeneration tank is discharged to the ion exchange tank, and then the time for replenishing regeneration material is reported by controlling the alarming device. 
         [0123]    The reference position of the floating body corresponds to a position satisfying the reference value of the water level of the regeneration water and the reference value of the density of the regeneration material. 
         [0124]    As is apparent from the above description, the plurality of valves can control on/off of a plurality of through holes formed on a path along which wash water flows, so that the path is simplified and the material cost is reduced. 
         [0125]    In addition, the water level sensor capable of controlling the water level of the regeneration water and the amount of regeneration material is mounted on the regeneration tank, so as to prevent increase of the material cost incurring from installing a plurality of sensors and minimize the waste of regeneration material, so that the water softening efficiency is enhanced. 
         [0126]    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 disclosure, the scope of which is defined in the claims and their equivalents.