Patent Publication Number: US-9841217-B2

Title: Ice making device, refrigerator including ice making device, and method of controlling refrigerator

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 U.S.C. 119 and 35 U.S.C. 365 to Korean Patent Application No. 10-2014-0021056 filed on Feb. 24, 2014 and Korean Patent Application No. 10-2014-0021848 filed on Feb. 25, 2014, which are hereby incorporated by reference in their entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to a refrigerator and a control method thereof. 
     BACKGROUND 
     Generally, refrigerators are home appliances for storing foods at a low temperature. In some cases, refrigerators can include a water supply container in a refrigerating compartment, an ice maker for making an ice piece in a freezing compartment, and a pump for forcibly supplying water within the water supply container to the ice maker. In some cases, refrigerators can include an ice making tray having a plurality of cells, an ejector for ejecting an ice piece in the cell, a driving motor for driving the ejector, and a heater for heating the ice making tray. In some cases, refrigerators can include an ice maker and an ice bin on a refrigerating compartment door, where the ice maker is connected to a motor assembly to separate an ice piece in a twisting manner. 
     SUMMARY 
     According to one aspect, a refrigerator includes a main body defining a storage compartment, a door configured to open and close at least a portion of the storage compartment, an ice making device disposed in the storage compartment or on a back surface of the door, a water tank disposed above the ice making device and configured to supply water for making ice pieces into the ice making device, and an ice bin disposed under the ice making device to receive and store ice pieces made in the ice making device. The ice making device includes an ice making tray having a plurality of ice making chambers that are configured to be filled with water for making the ice pieces, and an ejector extending from an upper central portion of the ice making tray in a longitudinal direction of the ice making tray to pass through both ends of the ice making tray. The ejector is configured to be maintained in a fixed state during water supply, ice making, and ice separation processes, and the ice making tray is configured to rotate at an angle of about 360° in one direction with respect to the ejector. 
     Implementations according to this aspect may include one or more of the following features. For example, the ejector may include a fixing shaft passing through both ends of the ice making tray, and a plurality of arms that radially extend from an outer circumferential surface of the fixing shaft, wherein, based on the ice making tray rotating, the plurality of arms are configured to press the ice pieces generated in the ice making chambers to eject the ice pieces from the ice making tray. The plurality of arms may be spirally disposed to be spaced a predetermined distance from each other on the outer circumferential surface of the fixing shaft in a longitudinal direction so that the ice pieces made in the ice making chambers are successively separated by a corresponding time difference. Each of the plurality of arms may be configured to press an edge of a top surface of each of the ice pieces generated in the ice making chambers, to thereby eject the ice pieces from the ice making chamber, and the edge of the top surface of each of the ice pieces being pressed by the arm may have a width less than that of an opposite edge of the top surface of each of the ice pieces. The water tank may include a water discharge hole defined in a bottom surface thereof, and a valve configured to open and close the water discharge hole. The ice making tray may further include a first rotation shaft extending from one side surface thereof, and a second rotation shaft extending from the other side surface opposite to the one side surface. 
     According to this aspect, the refrigerator may further include a driving unit connected to the first rotation shaft, a valve operation unit fitted into an outer circumferential surface of the second rotation shaft to integrally rotate with the ice making tray, and an operation member having a first end that is in contact with an outer circumferential surface of the valve operation unit and a second end that is connected to the valve, the operation member being configured to convert a rotation force of the valve operation unit into linear reciprocating movement to operate the valve. The valve operation unit may have one side having a cam shape protruding in a radial direction to elevate the operation member when the cam rotates. The driving unit may include an alternating current (AC) motor configured to rotate in at least one direction, and a power transmission unit configured to transmit a rotation force of the AC motor to the ice making tray, wherein the power transmission unit includes a gear assembly. The refrigerator may further include a tray support for supporting the ice making tray, wherein the tray support includes a shaft coupling unit horizontally protruding from one surface thereof to support the second rotation shaft, and a movement guide extending upward from the other surface thereof to surround at least a portion of the operation member and to thereby guide movement of the operation member. The fixing shaft may have one end that passes through the second rotation shaft and fixedly supported by the shaft coupling unit, and the second rotation shaft may be rotatably supported by the shaft coupling unit. The refrigerator may further include a tank support configured to support the water tank, wherein the tank support includes a through-hole through which the movement guide passes, and a water guide unit configured to guide the water discharged from the water discharge hole into the ice making tray. The refrigerator may further include a heater mounted on the tank support. 
     Also under this aspect, the storage compartment may include a freezing compartment, and the door may include a freezing compartment door. The ice making device and the water tank may be disposed on the freezing compartment door, and the refrigerator may further include a heat insulation box disposed on a back surface of the freezing compartment door to accommodate the water tank therein. The water tank may be disposed on an outer top surface of the main body, the ice making device may be disposed in the freezing compartment, and the water discharged from the water tank may pass through the main body to be supplied into the ice making device. The refrigerator may further include a temperature sensor mounted on a surface of the ice making tray to detect a temperature of the ice making tray, electrodes electrically connected to the temperature sensor, the electrodes being disposed on a side surface of the ice making tray facing the tray support, contact points disposed on the tray support and configured to electrically contact the electrode, and a controller electrically connected to the contact point and configured to receive the temperature value of the ice making tray. Each of the electrodes may be disposed on an end of the valve operation unit that is in contact with the tray support, and each of the contact points may be disposed on a circumference corresponding to a rotation trace of the electrode. The contact points may be disposed on one or a plurality of points along the circumference. Each of the contact points may have an arc shape having a predetermined length along the circumference. Each of the contact points may have a circular shape over an entirety of the circumference. The electrodes may include a first electrode, and a second electrode disposed at a position that is radially spaced apart from the first electrode, wherein the contact points include a first contact point corresponding to the first electrode, and a second contact point corresponding to the second electrode. The refrigerator may further include a heater mounted on the water tank, the heater being configured to be controlled in on/off operation by the controller based on the temperature value detected by the temperature sensor. 
     According to another aspect, a method, which is for controlling a refrigerator including a main body having a storage compartment, a door configured to open and close at least a portion of the storage compartment, an ice making device disposed in the storage compartment or on a back surface of the door, a water tank disposed above the ice making device to supply water for making ice pieces into the ice making device, and an ice bin disposed under the ice making device to receive and store ice pieces made in the ice making device, wherein the ice making device includes an ice making tray having a plurality of ice making chambers that are configured to be filled with water for making the ice pieces, and an ejector extending from an upper central portion of the ice making tray in a longitudinal direction of the ice making tray to pass through both ends of the ice making tray, may include maintaining the ejector in a fixed state, performing water supply, ice making, and ice separation processes, and while the ice making tray successively performs water supply, ice making, and ice separation processes, rotating the ice making tray 360° in one direction with respect to the ejector. 
     Implementations according to this aspect may include one or more of the following features. For example, the water supply process may include rotating the ice making tray to a first position where the water is supplied into the ice making tray, maintaining the ice making tray in the first position until water is filled by a predetermined amount into the ice making tray, rotating the ice making tray from the first position to a second position where the water supplied into the ice making tray is distributed into the plurality of ice making chambers, and maintaining the ice making tray in the second position to enable freezing of the ice pieces to start. The method may further include detecting a temperature of the ice making tray by using a temperature sensor mounted on the ice making tray after the water supply process is performed, and controlling, by a controller, an on/off operation of a heater mounted on the water tank depending on a temperature value detected by the temperature sensor. Based on the water supply process being completed, and based on determining that the temperature value detected by the temperature sensor reaches a preset temperature, the heater may be allowed to be maintained in an on state. Based on the water supply process being completed, and based on determining that the temperature value detected by the temperature sensor does not reach the preset temperature, the water supply process may be allowed to be repeatedly performed. Based on the water supply process being repeatedly performed, and based on determining that the temperature value detected by the temperature sensor does not reach the preset temperature, the heater may be turned off. Generating, by the controller, a water replenishing signal at the same time as or after turning off operation of the heater. The method may include generating, by the controller, a water replenishing signal at the same time as or after turning off operation of the heater. 
     The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an example refrigerator according to a first implementation. 
         FIG. 2  is a perspective view of a freezing compartment door according to the first implementation. 
         FIG. 3  is a perspective view showing an example arrangement of a water tank and an ice making device according to the first implementation. 
         FIG. 4  is an exploded perspective view showing an example ice making assembly according to the first implementation. 
         FIG. 5  is a plane view showing an example state in which an ice making tray and an ejector are disposed according to the first implementation. 
         FIG. 6  is a view showing a direction of a force of the ejector applied to an ice piece generated in the ice making tray in  FIG. 5 . 
         FIGS. 7A-7F  are schematic views showing an example operation of an ice making assembly according to the first implementation. 
         FIGS. 8A-8B  are partially enlarged views showing portions A and B of  FIGS. 7A and 7B . 
         FIG. 9  is a schematic view showing an example refrigerator according to a second implementation. 
         FIG. 10  is a schematic view showing an example refrigerator according to a third implementation. 
         FIG. 11  is a schematic view showing an example refrigerator according to a fourth implementation. 
         FIG. 12  is a front view showing an example refrigerator according to an implementation. 
         FIG. 13  is a perspective view showing the refrigerator of  FIG. 12  in which a door is in an opened state. 
         FIG. 14  is a schematic view showing an example ice making device according to an implementation. 
         FIG. 15  is a diagram showing a temperature sensor, a controller, and an ice separation motor disposed in the ice making device. 
         FIG. 16  is a perspective view showing an example shape of a contact point disposed on a frame of the ice making device. 
         FIGS. 17 to 19  are perspective views showing example shapes of a contact point disposed on a frame of an ice making device according to another implementation. 
         FIG. 20  is a flowchart showing an example method of controlling the refrigerator according to an implementation. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the implementations of the present disclosure, examples of which are illustrated in the accompanying drawings. 
     Referring to  FIGS. 1 and 2 , a refrigerator  1  according to a first implementation may include a main body  10  including a freezing compartment  11  and a refrigerating compartment  12  disposed under the freezing compartment  11 , a freezing compartment door  13  connected to the main body  10  to open and close the freezing compartment  11 , and a refrigerating compartment door  14  connected to the main body  10  to open and close the refrigerating compartment  12 . In the current implementation, the freezing compartment  11  and the refrigerating compartment  12  are commonly called a storage compartment, and the freezing compartment door  13  and the refrigerating compartment door  14  are commonly called a refrigerator door. 
     The freezing compartment door  13  may include an outer case  17  defining an outer appearance, a door liner  15  for covering the freezing compartment  11 , and a décor member  19  connecting the door liner  15  to the outer case  17 . 
     An ice making assembly for generating and storing ice pieces may be disposed on the door liner  15 . The ice making assembly may include an ice making device  20  for generating the ice pieces and an ice bin  30  for storing the ice pieces generated in the ice making device  20 . 
     Also, a heat insulation box  151  may be disposed on a back surface of the freezing compartment door  13 . The heat insulation box  151  may be defined as a unit of the door liner  15 . Also, the heat insulation box  151  may define a space for accommodating a water tank (see reference numeral  40  of  FIG. 3 ) in which water for making ice pieces is stored. 
     Also, a box cover  152  may open and close an inner space of the heat insulation box  151 . A heat insulation material may be further provided in a space defined by the heat insulation box  151  and the box cover  152 . 
     Also, the box cover  152  may be separated from the heat insulation box  151  to install the water tank  40  into the heat insulation box  151  or to separate the water tank  4  from the heat insulation box  151 . 
     In the current implementation, since the water tank  40  is disposed in the heat insulation box  151 , a phenomenon in which the water tank  40  is frozen by chill air of the freezing compartment may be prevented even though the water tank  40  is disposed in the freezing compartment door  13 . 
     Referring to  FIGS. 2 to 4 , the water tank  40  according to the first implementation may be disposed directly above the ice making device  20 . 
     A tank support  50  for supporting the water tank  40  may be disposed in the heat insulation box  151 . The water tank  40  may be separably seated on a top surface of the tank support  50 . 
     The water tank  40  may include a tank body  410  defining a space in which water is stored and a tank cover  420  for opening and closing the tank body  410 . 
     An opening  412  may be defined in the tank body  410 . The tank cover  420  may open and close the opening  412 . The tank cover  420  may be separably or rotatably coupled to the tank body  410 . 
     A user may separate the water tank  40  from the freezing compartment door  13  and open the opening  412  to supply the water into the tank body  410 . Also, the user may clean inside the tank body  410  in a state where the opening  412  is opened. 
     A hole  422  through which air flows may be defined in the tank cover  420 . The user may supply the water into the tank body  410  through the hole  422  without separating the tank cover  420  from the tank body  410 . 
     A seating guide  510  may inclinedly protrude from a top surface of the tank support  50 . An accommodation  414  into which the seating guide  510  is accommodated may be defined in a lower portion of the tank body  410 . The seating guide  510  may be accommodated into the accommodation unit  414  to prevent a phenomenon in which the water tank  40  horizontally oscillates while the freezing compartment door  13  is opened or closed. The user may lift the water tank  40  to separate the water tank  40  from the tank support  50 . 
     A lower wall  415  of the tank body  410  may be inclined downward to correspond to a shape of the seating guide  510 . Also, a water discharge hole (see reference numeral  418  of  FIG. 8 ) for discharging the water may be defined in a spot of the lower wall  415 , which corresponds to the lowest portion of the lower wall  415 . Also, the tank body  410  includes a valve assembly  430  for opening and closing the water discharge hole  418 . An operation of the valve assembly  430  will be described below with reference to the accompanying drawings. 
     The tank support  50  may be coupled to the heat insulation box  151  or integrated with the heat insulation box  151 . 
     A water guide hole  520  for guiding the water discharged from the water discharge hole  418  to the ice making device  20  may be defined in the top surface of the tank support  50 . To prevent the water discharged from the water discharge hole  418  from leaking into a space between the top surface of the tank support  50  and a bottom surface of the water tank  40 , a portion of the water discharge hole  418  may be inserted into the water guide hole  520 . 
     The ice making device  20  may include an ice making tray  210  including a plurality of ice making chambers  212  for generating ice pieces, a driving unit  280  for rotating the ice making tray  210 , and valve operation units  230  and  240  transmitting rotational force of the ice making tray  210  to the valve assembly  430  to operate the valve assembly  430 . 
     The ice making tray  210  may include a water supply guide  220  for guiding the water supplied from the water tank  40  to the plurality of ice making chambers  212 . The water supply guide  220  may extend upward from a top surface of the ice making tray  210 . 
     A first rotation shaft  214  and a second rotation shaft  215  which are rotational centers of the ice making tray  210  may be disposed on both side surfaces of the ice making tray  210 . The rotation shafts  214  and  215  may be respectively rotatably supported by tray supports that are disposed at both sides of the ice making tray  210 . 
     The tray supports  272  and  274  may include a first support  272  and a second support  274 . In detail, the first rotation shaft  214  disposed on one side of the ice making tray  210  may pass through the first support  272 . Also, the second rotation shaft  215  disposed on the other side of the ice making tray  210  may be coupled to the second support  274 . 
     The driving unit  280  may be coupled to the first support  272 . In some cases, the driving unit  280  may include an AC motor that is rotatable in one direction and a power transmission unit for transmitting power of the AC motor to the first rotation shaft  214  of the ice making tray  210 . For example, the power transmission unit may be a gear, but not be limited thereto. 
     In the current implementation, the AC motor that is relatively inexpensive in comparison to a bidirectionally rotatable DC motor may be adapted to reduce manufacturing costs of the refrigerator. 
     The first rotation shaft  214  may pass through the first support  272  and thus be connected to the driving unit  280 . For another example, a portion of the power transmission unit or a shaft of the AC motor, which constitute the driving unit  280 , may pass through the first support  272  and thus be coupled to the first rotation shaft  214  of the ice making tray  210 . 
     A shaft coupling unit  275  inserted into the second rotation shaft  215  may protrude from the second support  274 . The second coupling unit  275  may support the second rotation shaft  215  and also guide rotation of the second rotation shaft  215 . 
     The valve operation units  230  and  240  may include a cam  230  coupled to the second rotation shaft  215  and an operation member  240  linearly reciprocating in a vertical direction in a state where the operation member  240  is in contact with an outer circumferential surface of the cam  230 . 
     The cam  230  may be coupled to the second rotation shaft  215  to integrally rotate with the second rotation shaft  215 . The cam  230  may include a cylindrical cam body  231  having a shaft coupling hole  232  and a protrusion  234  protruding from the outer circumferential surface of the cam body  231 . 
     The second rotation shaft  215  may be rotatably connected to the shaft coupling unit  275  in a state where the second rotation shaft  215  is inserted into the shaft coupling hole  232 . For example, the second rotation shaft  215  may be rotatably inserted into the shaft coupling unit  275 . On the contrary, the shaft coupling unit  275  may be rotatably inserted into the second rotation shaft  215 . 
     The operation member  240  may have a transversal section having a non-circular shape. For example, the operation member  240  may have a column or oval column shape having a polygonal section and have any shape having a non-circular section. The operation member  240  may contact a circumference of the cam body  231  and the protrusion  234  when the cam  230  rotates. 
     In detail, one or more rollers  244  may be disposed on a lower end of the operation member  240  to prevent a contact surface between the operation member  240  and the cam  230  from being damaged and to smoothly transmit rotation force of the cam  230  to the operation member  240 . Also, a roller coupling unit  242  to which the one or more rollers  244  are mounted is disposed on the lower end of the operation member  240 . Thus, the one or more rollers  244  of the operation member  240  may substantially contact the cam  230 . 
     The protrusion  234  may have a round or inclined shape so that the operation member  240  linearly moves by receiving the rotation force of the cam  230 . 
     A movement guide  277  for guiding linear movement of the operation member  240  in a vertical direction may extend from the second support  274 . Also, the operation member  240  may be inserted into the movement guide  277 . Alternatively, the movement guide  277  may surround a portion of the operation member  240 . Thus, a portion or whole of a horizontal section of the movement guide  277  may be the same as that of a horizontal section of the operation member  240 . 
     The operation member  240  may ascend by the rotation of the cam  230  to operate the valve assembly  430  when the ice making tray  210  rotates in one direction to separate the ice pieces therefrom. 
     A through-hole  530  through which the movement guide  277  and the operation member  240  pass may be defined in the tank support  50 . A portion or whole of a horizontal section of the through-hole  530  may be the same as that of a horizontal section of the movement guide  277 . Also, since each of the movement guide  277  and the operation member  240  has the non-circular horizontal section, a phenomenon in which the operation member  240  idly rotates about a vertical axis passing through a center thereof while the operation member  240  vertically linearly moves may be prevented. Thus, the operation member  240  may stably transmit the rotation force of the ice making tray  210  to the valve assembly  430 . 
     The ice making assembly may further include an ejector  260  for separating each of the ice pieces generated in each of the ice making chambers  212  from the ice making tray  210  while the ice making tray  210  rotates. The ejector  260  may be disposed at an upper side of the ice making tray  210 . Also, the ejector  260  may have one end that is relatively rotatably connected to the ice making tray  210  and the other end that passes through the second rotation shaft  215  and is inserted into the shaft coupling unit  275 . That is, the one end of the ejector  260  may be idly coupled to a side surface of the ice making tray  210 . Thus, the ejector  260  may be maintained in a stopped state when the ice making tray  210  rotates. Thus, according to the current implementation, the driving unit  280  may not be provided to rotate the ejector  260  but be provided to rotate the ice making tray  210 . This is a difference between the current implementation and the ice making device according to the related art in which the ejector rotates. 
     Referring to  FIGS. 5 and 6 , the ice making tray  210  according to the current implementation includes a plurality of ice making chamber  212  as described above. Also, a water supply guide  220  may extend from one side of the ice making tray  210 . 
     The ejector  260  may include a fixing shaft  262 , a plurality of arms  264  radially extending from a circumference of the fixing shaft  262  to scoop up the ice pieces generated in the ice making chambers  212 . 
     The fixing shaft  262  may extend in a longitudinal direction of the ice making tray  210 . The fixing shaft  262  may be disposed at a position that coincides with a central line of the ice making tray  210  extending in the longitudinal direction of the ice making tray  210 . That is, the fixing shaft  262  may be disposed on a central portion of the top surface of the ice making tray  210  and extend in the longitudinal direction of the ice making tray  210 . 
     As illustrated in  FIG. 4 , the fixing shaft  262  may pass through both side surfaces of the ice making tray  210 . The fixing shaft  262  may have one end that is fixedly connected to the shaft coupling unit  275  disposed on the tray support  274 . Also, the fixing shaft  262  may pass through the first and second rotation shafts  214  and  215  and thus be maintained in a fixed state even though the first and second rotations shafts  214  and  215  rotate. 
     The ice making chamber  212  may have the one end having a width W 1  that is less than that W 2  of the other end thereof so that the ice piece generated in the ice making chamber  212  is easily separated by the ejector  260 . That is, the ice making chamber  212  may have a width that gradually increases from the one end to the other end thereof. Thus, the ice piece generated in the ice making chamber  212  may have widths which are different from each other at one side and the other side of the ice piece. 
     The plurality of arms  264  may be spirally disposed along the fixing shaft  262  so that the ice pieces generated in the plurality of ice making chambers  212  are successively separated from the ice making tray  210  while the ice making tray  210  rotates. 
     In detail, the plurality of arms  264  may be spaced a predetermined distance apart from each other on an outer circumferential surface of the fixing shaft  262  in a longitudinal direction of the fixing shaft  262 . The plurality of arms  264  may be disposed in a spiral shape to wind around the fixing shaft  262 . Then, since the ice pieces generated in the plurality of ice making chambers  212  are successively separated by time difference, the ice making tray  210  may rotates with a relatively small force. 
     According to the current implementation, since the AC motor is used to rotate the ice making tray  210 , the AC motor may provide less torque compared to the DC motor. 
     Thus, in the current implementation, the ice pieces generated in the plurality of ice making chambers  212  may be successively separated one by one so that the ice pieces generated in the ice making tray  210  are easily separated from the ice making tray  210  by the low torque. 
     Also, as illustrated in  FIG. 6 , to easily separate the ice piece I of the ice making chamber  212  from the ice making tray  210 , each of the arms  264  may press a portion having a relatively small width of a top surface of the ice piece I by a predetermined force F when the ice making tray  210  rotates. 
     In detail, when the arm  264  presses the portion, which has a relatively small width, of the top surface of the ice piece I, an end of the top surface, which has a relatively large width, of the ice piece may protrude from the top surface of the ice making tray  210 . Also, an end of the top surface having a relatively small width of the ice piece may move along a rounded bottom surface of the ice making chamber  212 . 
     Also, since the ice making chamber  212  has a width that gradually increases from one end to the other end thereof, and the top surface of the ice piece having a relatively small width is pressed, when ice piece separation is started, a state in which a side surface of the ice piece contacts a side surface of the ice making chamber  212  may be released. Thus, a phenomenon in which the separation of the ice piece is interrupted by a friction force between the ice piece and the ice making tray  210  may be prevented. If the ice making chamber  212  has a uniform width like the structure of the ice making tray  210  according to the related art, the friction force may be applied between the side surface of the ice piece and the side surface of the ice making chamber  212  until the ice piece is perfectly separated from the ice making chamber  212 , and thus ice piece separation efficiency may be reduced. 
     Also, in the current implementation, since the water in the water tank  40  may free-fall and thus be supplied into the ice making tray  210  while the ice making tray  210  rotates, a water guide passage for distributing and supplying the water into each of the plurality of ice making chambers  212  is not necessary in the ice making tray  210 . 
     If the water guide passage is defined in the ice making tray  210 , the water existing in the water guide passage may be frozen to allow the ice pieces generated in the ice making chambers that are adjacent to each other to be connected to each other, thereby acting as a factor that disturbs the ice piece separation. Also, since the ice piece in the water guide passage has to be separated so as to separate the connected ice pieces, much torque may be required. However, in the current implementation, since the water guide passage connecting the two ice making chambers that are adjacent to each other is not defined in the ice making tray, the ice piece may be separated from the ice making tray even though the AC motor generating a relatively low torque is used. 
       FIG. 7A  is a view of the ice making assembly when the water supply is started, and  FIG. 7B  is a view of the ice making assembly while the water is supplied. Also,  FIG. 7C  is the ice making assembly after the water supply is completed. 
     Referring to  FIG. 7A , a heater  540  for heating the water tank  40  may be disposed in the tank support  50  so as to prevent the water in the water tank  40  from being frozen. In the current implementation, since the water tank  40  is disposed in the heat insulation box  151 , the freezing of the water in the water tank  40  may be minimized. Also, the freezing of the water in the water tank  40  may be prevented by the heater  540 . 
     In detail, supply of the water for making the ice pieces may be started in a state where the ice making tray  210  rotates in a predetermined angle as illustrated in  FIG. 7A . That is, the supply of the water may be started in a state where a water supply guide  220  inclinedly rotates. Then, the water stored in the water tank  40  may be discharged to the outside through the valve assembly  430 . The water discharged from the valve assembly  430  may fall into the water supply guide  220 . Here, since the water supply guide  220  is in the inclined state, the supplied water may be uniformly supplied to the plurality of ice making chambers  212  without a separate water guide passage. Also, the ice making tray  210  may gradually rotate in a direction in which the water supply guide  220  is in an upright state while the water is supplied to prevent the supplied water from flowing down to the outside. Also, when the water is completely supplied, an angle formed between the water supply guide  220  and a horizontal plane may be about 45°, however, it is not limited thereto. That is, a predetermined angle less than about 90°, at which water does not flow down from the ice making tray  210 , may be set. 
     Also, when the water is completely supplied, the first ice making tray  210  rotates so that the water supply guide  220  is perpendicular to the horizontal plane. The ice making may be started in the state where the water supply guide  220  is perpendicular to the horizontal plane. 
       FIG. 7D  is a view of the ice making assembly when the ice separation is started, and  FIG. 7 e    is a view of the ice making assembly while the ice separation is performed. Also,  FIG. 7F  is a view of the ice making assembly when the ice separation is completed. 
     As illustrated, when the ice making is completed, the ice making tray  210  may start to rotate in the same direction as that in which the ice making tray  210  rotates while the water is supplied so that the ice piece is separated from the ice making tray  210  by the ejector  260 . The arm  264  of the ejector  260  may press a top surface of a rear end of the ice piece having a relatively small width to allow the ice piece to be separated from the ice making tray  210 . Here, the rear end of the ice piece may represent an end at a side of the water supply guide  220 . 
       FIG. 8A  is an enlarged view of portion A of  FIG. 7A .  FIG. 8B  is an enlarged view of portion B of  FIG. 7B . 
     First, referring to  FIG. 8A , the valve assembly  430  in the current implementation may be coupled to a valve coupling part  416  disposed on the tank body  410 . The valve coupling part  416  may be one end that is disposed in the tank body  410  and the other end that protrudes upward from the tank body  410 . Also, a portion of the valve assembly  430  may be inserted into the valve coupling part  416 . 
     The valve coupling part  416  may communicate with the water discharge hole  418  defined in the lower wall  415  of the tank body  410 . Also, an introduction hole  417  into which the water in the tank body  410  is introduced may be defined in the valve coupling part  416 . The valve assembly  430  may open and close the introduction hole  417  or the water discharge hole  418 . That is, the valve assembly  430  may allow the introduction hole  417  to communicate with the water discharge hole  418  or prevent the introduction hole  417  from communicating with the water discharge hole  418 . 
     The valve assembly  430  includes a valve body  434  inserted into the valve coupling part  416  from an upper end of the valve coupling part  416 , a rod  433  passing through the valve body  434 , a valve member  432  disposed on a lower end of the rod  433  to open and close the water discharge hole  418 , a valve lever  436  connected to an upper end of the rod  433  to operate by the valve operation units  230  and  240 , and an elastic member  437  disposed between the valve body  434  and the valve member  432  and fitted into an outer circumferential surface of the rod  433 . 
     The valve member  432  may be a rubber packing member to simultaneously block or open the introduction hole  417  and the discharge hole  418 , thereby controlling discharge of the water. 
     The elastic member  437  may apply a force for moving valve member  432  in a direction in which the water discharge hole  418  is closed to the valve member  432 . 
     The valve lever  436  may receive the force from the valve operation units  230  and  240  to rotate, thereby lifting the rod  433  so that the introduction hole  417  communicates with the water discharge hole  418  through the valve member  432 . 
     The water passing through the introduction hole  417  may flow along an outer surface of the valve member  432  and an inner surface of the valve coupling part  416  and then be discharged through the water discharge hole  418 . Here, since the discharged water does not contact the elastic member  437 , the elastic member  437  may be prevented from rusting, and thus the water tank may have excellent sanitation. 
     Referring to  FIGS. 7C and 8A , during the ice making, the operation member  240  is maintained in a state where the operation member  240  contacts the cam body  231 , and the valve assembly  430  is maintained in a state where the communication between the introduction hole  417  and the water discharge hole  418  is blocked. 
     The water supplied into the ice making chambers  212  may be cooled and frozen by the cool air of the freezing compartment  11 . In some cases, a temperature sensor may be disposed on the ice making tray  210 . The controller may determine whether the ice making is completed on the basis of a temperature detected by the temperature sensor. 
     When it is determined that the ice making is completed, the controller may operate the driving unit  280  so that the ice making tray  210  rotates in one direction. 
     As illustrated in  FIGS. 7D and 7E , when the driving unit  280  operates, the rotation force of the motor may be transmitted to the ice making tray  210  to rotate the ice making tray  210  in a counterclockwise direction. 
     While the ice making tray  210  rotates in the counterclockwise direction, the ice pieces generated in the ice making chambers  212  may be successively separated by the ejector  260 . While the ice making tray  210  rotates in the counterclockwise direction, the operation member  240  may contact the outer circumference of the cam body  231 . However, the operation member  240  does not ascend. 
     As illustrated in  FIG. 7F , the operation member  240  may contact the cam body  231  but not contact the protrusion  234  in a state where the ice separation is completed. 
     When the ice making tray  210  further rotates in the counterclockwise direction in the state where the ice separation is completed, the operation member  240  may contact the protrusion  234  as illustrated in  FIG. 7A . Also, when the ice making tray  210  further rotates in the counterclockwise direction, the operation member  240  may ascend in a state where the operation member  240  contacts the protrusion  234 . 
     When the operation member  240  ascends, the valve lever  436  is lifted as illustrated in  FIG. 8B . When the valve lever  436  is lifted, the valve lever  436  may allow the rod  433  to ascend. When the rod  433  ascends, the valve member  432  connected to the rod  433  ascends to allow the introduction hole  417  to communicated with the water discharge hole  418 . Thus, the water in the water tank  40  may be discharged through the water discharge hole  418 . The water discharged through the water discharge hole  418  may pass through the water guide hole  520  of the tank support  50  to fall into the water supply guide  220  of the ice making tray  210 . 
     Also, as illustrated in  FIG. 7C , when the ice making tray  210  further rotates in the counterclockwise direction, the water fell into the water supply guide  220  may be distributed into each of the ice making chambers  212  of the ice making tray  210 . Also, the operation member  240  may climb over the protrusion  234  of the cam  230  to descend. Here, the operation member  240  may descend by the self-weight and by the rotation force of the valve lever  436  according to a restoring force of the elastic member in the valve assembly  430 . 
     In the state illustrated in  FIG. 7C , the ice making tray  210  may be stopped, and the supply of the water may be completed. 
     In the current implementation, an amount of water discharged of the water discharge hole  418  or an amount of water supplied into the ice making tray  210  may vary according to time in which the introduction hole  417  communicates with the water discharge hole  418  according to the operation of the valve assembly  430 . 
     In the current implementation, the communication time may vary according to a rotation rate of the ice making tray  210  or a length or shape of the protrusion  234  of the cam. 
     For example, the rotation of the ice making tray  210  may be controlled so that the ice making tray  210  has a rotation rate while the water is supplied, which is less than that of the ice making tray  210  while the ice is separated. Of course, the ice making tray  210  may be maintained at a uniform rotation rate. Or, the ice making tray may be stopped in a state where the ice making tray  210  rotates as illustrated in  FIG. 7B  and then rotate again after a predetermined time elapses. 
     That is, referring to the process illustrated in  FIGS. 7A-7F , in the current implementation, when a process in which the ice piece is made in the ice making tray is called a ice making process, a water supply process in which the water in the water tank is supplied into the ice making tray, the ice making process in which the ice piece is generated in the ice making tray, and a ice separation process in which the ice piece generated in the ice making tray is separated after the ice making process is completed may be successively performed while the ice making tray rotates in one direction within a range of one revolution. 
     Also, the water supply process may include a first rotation process in which the ice making tray rotates to a position for receiving the water, a standby process for waiting until the water is filled in the ice making tray, and a second rotation process in which the ice making tray rotates so as to distribute the water supplied into the ice making tray to each of the ice making chambers. 
     Alternatively, the water supply process may be performed while the ice making tray continuously rotates. 
     According to the proposed current implementation, the water tank having the water discharge hole and the valve is disposed above the ice making tray, and the rotation force of the ice making tray may be transmitted to the valve by the valve operation unit to operate the valve. Thus, the water in the water tank may free fall and thus be supplied into the ice making tray without a pump and an electronic valve adjusting a flow rate. 
     Thus, since it is unnecessary to use a pump and an electronic valve, the refrigerator may be reduced in manufacturing costs. Also, a control program for controlling the pump and the electronic valve may not be required. 
       FIG. 9  is a schematic view of a refrigerator according to a second implementation. 
     The current implementation is the same as the first implementation except for a position of an ice making assembly. Thus, only specific portions of the current implementation will be described below. 
     Referring to  FIG. 9 , a water tank  40 , an ice making device  20 , and an ice bin  30  may be disposed in a freezing compartment  11  in a refrigerator  2  according to the current implementation. A shelf  16  for partitioning the freezing compartment  11  into a plurality of spaces may be disposed in the freezing compartment  11 . The water tank  40  may be accommodated into a heat insulation box  151  disposed on the shelf  16 . 
     Also, the ice making device  20  and the ice bin  30  may be disposed at a lower side of the shelf  16 . 
       FIG. 10  is a schematic view of a refrigerator according to a third implementation. 
     The current implementation is the same as the first implementation except for a position of an ice making assembly. Thus, only specific portions of the current implementation will be described below. 
     Referring to  FIG. 10 , in a refrigerator according to the current implementation, a heat insulation box  151  into which a water tank  40  is accommodated is disposed on a ceiling surface of the freezing compartment  11 . An ice making device  20  may be disposed under the heat insulation box  151 . Also, an ice bin  30  may be disposed under the ice making device  20 . 
     A shelf  16  for partitioning the freezing compartment into a plurality of spaces may be disposed in the freezing compartment  11 . The ice making device  20  may be disposed on a lower portion of the heat insulation box  151 . The ice bin  30  may be seated on the shelf  16 . 
       FIG. 11  is a schematic view of a refrigerator according to a fourth implementation. 
     The current implementation is the same as the first implementation except for a position of an ice making assembly. Thus, only specific portions of the current implementation will be described below. 
     Referring to  FIG. 11 , in a refrigerator according to the current implementation, a water tank  40  may be disposed outside the main body  10  (see  FIG. 1 ), and an ice making device  20  and an ice bin  30  may be disposed in a freezing compartment  11 . 
     For example, the water tank  40  may be disposed on a top surface of the main body  10  or in a tank accommodation unit that is recessed downward from the top surface of the main body  10 . Also, the water in the water tank  40  may pass through the main body  10  and thus be supplied into the ice making device  20 . Of course, in this case, the water tank  40  has to be disposed directly above the ice making device  20 . Also, an operation member for transmitting a rotation force of the ice making tray may pass through the main body  10  to contact a valve of the water tank  40 . 
     In the current implementation, since the water tank  40  is disposed outside the main body, a heat insulation box is unnecessary. 
     For another example, according to the same principle as illustrated in  FIG. 11 , the water tank may be mounted on a freezing compartment door at the outside of the freezing compartment door. Also, the ice making tray and the ice bin may be disposed on a back surface of the freezing compartment door. In this case, the water tank has to be disposed directly above the ice making tray. For example, the front surface of the freezing compartment door may be recessed rearward to allow the tank accommodation unit to be defined in the freezing compartment door, and the ice making device may be disposed under the tank accommodation unit so that the water tank is disposed directly above the ice making tray. Also, the water discharged from the water tank may pass through the freezing compartment door and thus be supplied into the ice making device. 
     For further another example, the water tank, the ice making device, and the ice bin may be disposed in the refrigerating compartment door. That is, in some cases, a space for making ice pieces can be defined in the refrigerating compartment door, and the water tank, the ice making device, and the ice bin may be accommodated into the space. However, in this configuration, since the cool air in the freezing compartment is supplied into the space, the water tank may be disposed in the heat insulation box in the space to prevent the water in the water tank from being frozen. 
       FIG. 12  is a front view of a refrigerator according to an implementation, and  FIG. 13  is a perspective view of the refrigerator of which a door is in an opened state. 
     Referring to  FIGS. 12 and 13 , a refrigerator  1 ′ according to an implementation includes a main body  110  in which the storage compartment is defined therein and doors selectively shielding the storage compartment of the main body  110 , similar to what was illustrated in  FIG. 1 . 
     The storage compartment may include a freezing compartment  111  and a refrigerating compartment  112 . The freezing compartment  111  and the refrigerating compartment  112  may be partitioned into left and right sides by a barrier  101 . Of course, when the barrier  101  is horizontally disposed, the freezing compartment  111  and the refrigerating compartment  112  may be partitioned into upper and lower sides as illustrated in  FIG. 1 . 
     A plurality of shelves and a plurality of drawers for accommodating food may be provided in the freezing compartment  111  and the refrigerating compartment  112 . 
     Also, the door includes a freezing compartment door  113  and a refrigerating compartment door  114  for respectively shielding the freezing compartment  111  and the refrigerating compartment  112 . The freezing compartment door  113  and the refrigerating compartment door  14  may be rotatably mounted on the main body  110  to selectively shield the freezing compartment  111  and the refrigerating compartment  112 . 
     Door handles  134  and  141  may be respectively disposed on front surfaces of the freezing compartment door  113  and the refrigerating compartment door  114 . A dispenser  133  may be disposed on the front surface of the freezing compartment door  13 . The dispenser  133  may be disposed at one side of the freezing compartment door  113  and refrigerating compartment door  114 . 
     The dispenser  133  is a device for dispensing purified water used as drinking water or ice pieces from the outside. The dispenser  133  may communicate with a portion of an ice making device  120  that will be described later to dispense the ice pieces. 
     Here, the ice making device  120  may be disposed above the dispenser  133  and be protected by a first cover  131  and a second cover  132  disposed on the freezing compartment door  113 . 
       FIG. 14  is a schematic view of an ice making device according to an implementation, and  FIG. 15  is control constitutions of a temperature sensor, a controller, and an ice separation motor disposed in the ice making device. 
     Referring to  FIGS. 14 and 15 , the ice making device  120  may include an ice making tray  210 , a water tank  140 , a heater  540 , a temperature sensor  213 , electrodes  216  and  217 , a frame  22 , contact points  221  and  222 , and a controller  21 . 
     The ice making device  120  may determine whether the water is filled in the water tank  140  by using a principle in which, when water is supplied into the ice making tray  210  from the water tank  140 , a surface temperature of the ice making tray  210  increases higher than a freezing temperature due to the water supplied from the water tank  140 . Then, the ice making device  20  may determine whether the heater  540  disposed on the water tank  140  operates. 
     That is, when the surface temperature of the ice making tray  210  reaches a preset temperature, the ice making device  120  determines that the water is filled in the water tank  140  to continuously maintain the operation of the heater  540  disposed on the water tank  140 . 
     Also, when the surface temperature of the ice making tray  210  does not reach a preset temperature, the ice making device  120  rotates again the ice making tray  210  to perform the process for supplying water once again. Nevertheless, when the surface temperature of the ice making tray  210  does not reach the preset temperature, it may be determined that no water exists in the water tank  140 . Thus, the operation of the heater  540  disposed on the water tank  140  may be stopped, or the heater  540  may be maintained in a stopped state. Here, the preset temperature represents a temperature higher than the freezing temperature. 
     Like this, the ice making device  20  may appropriately control an on/off operation of the heater  540  according to whether the water is normally supplied into the ice making tray  210  to minimize power consumed by the heater  540 . 
     Constitutions and operation principles of the constitutions of the ice making device  120  may the same as those of the ice making device  20  illustrated in  FIGS. 1 to 11 . That is, the ice making tray  210  receives the water from the water tank  140 . The water tank  140  may include the water discharge hole. Also, the valve assembly  430  may be disposed on the water discharge hole. The ice making tray  210  operates the valve while rotating at an angle of about 360° by an ice separation motor  24  to allow the water to be supplied into the ice making tray  210 . The ice separation motor  24  may be the AC motor rotating in a single direction that is described in the descriptions with respect to  FIGS. 1 to 11 . 
     The heater  540  may heat the water tank  140  to prevent the water in the water tank  140  from being frozen. Also, the heater  540  may be stopped when no water is exists in a water container of the water tank  140  so as to minimize an amount of power consumption. 
     The ice making device  120  may determine whether the water exists in the water container of the water tank  140  by determining whether the water is normally supplied into the ice making tray  210  after the ice piece generated in the ice making tray  210  is separated. 
     Also, the ice making device  120  may determine whether the water is normally supplied into the ice making tray  210  by detecting whether the surface temperature of the ice making tray  210  rises by using the temperature sensor  213  mounted on the ice making tray  210 . 
     The temperature sensor  213  may be disposed on a bottom surface of the ice making tray  210 . However, the present disclosure is not limited to a position of the temperature sensor  213 . For example, the temperature sensor  213  may be disposed between the bottom surface and a top surface of the ice making tray  210 . 
     The temperature sensor  213  disposed on the ice making tray  210  may be electrically connected to the controller  21 . Thus, surface temperature information of the ice making tray  210  measured by the temperature sensor  213  may be transmitted to the controller  21 . 
     The electrodes  216  and  217  may include a first electrode  216  and a second electrode  217  that are fixed to a side surface of the ice making tray  210 . The contact points  221  and  222  may include a first contact point  221  contacting the first electrode  216  and a second contact point  222  contacting the second electrode  217 . 
     Each of the first and second electrodes  216  and  217  may be electrically connected to the temperature sensor  213  and fixed to the side surface of the ice making tray  210 . 
     Also, the first and second contact points  221  and  222  electrically connected to the controller  21  may be fixed to the frame  22  to which the ice making tray  210  rotatably coupled. 
     Here, for example, the frame  22  may correspond to the tray support  274  constituting the ice making device  20  described in  FIG. 4 . That is, the first and second contact points  221  and  222  may be disposed on a side surface of the tray support on which the shaft coupling unit  275  is disposed. In detail, the first and second contact points  221  and  222  may be disposed at a position that is spaced a predetermined distance apart from the shaft coupling unit  275 . 
     Also, the first and second electrodes  216  and  217  may be disposed on an end of the valve operation unit  230 . In detail, the first and second electrodes  216  and  217  may be disposed on an end of the cam  231  contacting the tray support  274 . 
     More particularly, the first and second contact points  221  and  222  may be disposed on the tray support  274  along a circumference corresponding to rotation trace of the first and second electrodes  216  and  217 . Also, the shaft coupling unit  275  may be a center of the circumference corresponding to the rotation trace of the first and second electrodes  216  and  217 . 
     Also, the first and second contact points  221  and  222  may be recessed in a predetermined depth from the frame  22  (or a surface of the tray support  274 ). Also, the first and second electrodes  216  and  217  may protrude from the side surface of the ice making tray  210  (or the end of the cam  231 ). This is done to increase a contact degree between the contact points  221  and  222  and the electrodes  216  and  217 . 
     The first and second contact points  221  and  222  may be respectively in contact with the first and second electrodes  216  and  217  at predetermined positions according to the rotation of the ice making tray  210 . 
       FIG. 16  is a view illustrating a shape of a contact point disposed on a frame of the ice making device. 
     Referring to  FIG. 16 , the first and second contact points  221  and  222  may be respectively disposed at a predetermined position on a movement path  216   a  of the first electrode  216  and a predetermined position on a movement path  217   a  of the second electrode  217  when the ice making tray  210  rotates. As illustrated, when the first and second contact points  221  and  222  are disposed at a predetermined position on the movement path  216   a  of the first electrode  216  and a predetermined position on the movement path  217   a  of the second electrode  217 , information of the temperature sensor  213  may be transmitted to the controller  21  from the temperature sensor  213  when the first contact point  221  contacts the first electrode  216 , and the second contact point  222  contacts the second electrode  217 . 
       FIGS. 17 and 19  are views of a shape of a contact point disposed on a frame of an ice making device according to another implementation. 
     Referring to  FIG. 17 , the first and second contact points  221  and  222  may have arc shapes and disposed in a predetermined section on the movement path  216   a  of the first electrode  216  and in a predetermined section on the movement path  217   a  of the second electrode  217 . 
     Referring to  FIG. 18 , the first and second contact points  221  and  222  may be disposed over a whole section on the movement path  216   a  of the first electrode  216  and over a whole section on the movement path  217   a  of the second electrode  217 . 
     Referring to  FIG. 19 , the first and second contact points  221  and  222  may be disposed at a plurality of positions on the movement path  216   a  of the first electrode  216  and a plurality of positions on the movement path  217   a  of the second electrode  217 . 
     The controller  21  may be electrically connected to the first and second contact points  221  and  222  to block power that is selectively supplied into the heater  540  according to the temperature of the ice making tray  210 . 
     That is, since the ice making device  20  has the electrodes  216  and  217  and the contact points  221  and  222  on portions on which the temperature sensor  213  is electrically connected to the controller  21 , there is no risk in damaging or twisting of an electric wire even though the ice making tray  210  rotates. 
     Hereinafter, a method of controlling the refrigerator for turning on/off the heater  540  will be described in detail. 
       FIG. 20  is a flowchart illustrating a method of controlling the refrigerator according to an implementation. 
     Referring to  FIG. 20 , in operation S 11 , a state in which the heater  540  mounted on the surface of the water tank  140  may be maintained at a turn-on state, and thus the water stored in the water tank  140  is maintained in a liquid state without being frozen may be defined as a basic state. 
     Then, in operation S 12 , when the ice piece is completely made, the ice making tray  210  rotates to separate the ice piece therefrom. In operation S 13 , after the ice piece is separated from the ice making tray  210 , the ice making tray  210  further rotates at a predetermined angle, and when the ice making tray  210  reaches a position for receiving water from the water tank  140 , a water supply operation is performed. Then, in operation S 14 , when the water is completely supplied, a temperature of the ice making tray  210  is detected by the temperature sensor  213 . 
     That is, after the ice piece is separated from the ice making tray  210 , the water discharge unit of the water tank  140  is opened to complete the supply of the water, and then the temperature of the ice making tray  210  may be measured by the temperature sensor  213 . Here, a time point at which a temperature of the ice making tray  210  is measured by the temperature sensor  213  may be a time point right after the water is completely supplied as illustrated in  FIG. 7 b   , or at which the ice making tray  210  rotates until the ice making operation starts after the water is completely supplied as illustrated in  FIG. 7   c.    
     When the temperature measured by the temperature sensor  213  reaches a preset temperature, it may be determined that water exists in the water tank  140 , and thus the operation of the heater  540  is continuously maintained. That is, if the water exists in the water tank  140 , when the water is supplied into the ice making tray  210  from the water tank  140 , the ice making tray  210  may increase in temperature. Thus, the temperature measured by the temperature sensor  213  may be changed from a freezing temperature into a preset temperature that is higher than the freezing temperature. 
     If a temperature measured by the temperature sensor  213  does not reach a preset temperature, in operation S 16 , the ice making tray  210  further rotates once again to repeat the water supply operation. Then, in operation S 17 , a temperature of the ice making tray  210  is detected again by the temperature sensor  213 . In operation S 18 , it may be detected again whether the temperature of the ice making tray  210  reaches a preset temperature. Also, when it is determined that the temperature of the ice making tray  210  reaches a temperature higher than the preset temperature, the water may be normally supplied. Thus, it is determined that the water exists in the water tank  140 , and thus the control process is completed. 
     In detail, a case in which after the ice making tray  210  rotates to separate the ice piece therefrom, the water is not supplied into the ice making tray  210  from the water tank  140  due to malfunction of the water tank  140  may occur. In this case, the water supply operation may be performed again to determine whether the water tank  140  is empty or it is simple malfunction of the water tank  140 . 
     When a temperature of the ice making tray  210  does not reach a preset temperature even though the water supply operation is performed again, in operation S 19 , it is determined that no water exists in the water tank  140 , and the operation of the heater  540  is stopped. In some cases, when the operation of the heater  540  is stopped, an alarm signal for notifying water replenish may be generated at the same time. 
     Through the above processes, it may be determined whether the heater  540  operates by determining whether the water exists in the water tank  140  to reduce power consumption. 
     According to the refrigerator and method of controlling the refrigerator according to the implementations, there are effects as follows. 
     First, in the ice making assembly according to the implementation, the water tank including the valve for opening and closing the water discharge hole may be disposed above the ice making tray. Here, the rotation force of the ice making tray may be transmitted to the valve through the valve operation unit to operate the valve. As a result, the water stored in the water tank may be freely fallen and thus be supplied into the ice making tray without the pump for supplying the water and the electronic valve for adjusting the flow rate. Thus, since it is unnecessary to use the pump and the electronic valve, cost for manufacturing the refrigerator may be reduced. Furthermore, the control program for controlling the pump and the electronic valve may be unnecessary. 
     Second, the ice making chamber may have the width that gradually decreases from one side to the other side thereof, and the arm of the ejector may firstly contact the portion of the ice, which has the relatively narrow width, separated from the ice making tray while the ice making tray rotates to press the ice piece to be separated. Thus, even though the inexpensive AC motor is used, the ice piece may be easily separated from the ice making tray. Also, since the tray has to rotate in only one direction, the motor rotating in the single direction may be used to reduce the manufacturing costs. 
     Third, since the elastic member disposed in the valve does not contact the water, the rusting of the elastic member may be prevented to improve sanitation of the water tank. 
     Fourth, even though the ice making tray rotates, the electrically connected portion of the temperature sensor may not interfere with the ice making tray. 
     Fifth, the heater disposed on the water tank may be efficiently controlled in operation to minimize power consumption due to the operation of the heater. 
     Sixth, since the operation of the heater is stopped in a state where no water exists in the water tank, the phenomenon in which the water tank is overheated may be prevented. Also, the malfunction or the breakdown of the refrigerator may be prevented. 
     Although implementations have been described with reference to a number of illustrative implementations thereof, it should be understood that numerous other modifications and implementations can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.