Abstract:
An ice making assembly for a refrigerator and a method for controlling the ice making assembly. The ice making assembly and the method of controlling the ice making assembly producing transparent ice and capable of preventing water overflow, the freezing of water that has overflowed, and the spilling out of water that has overflowed.

Description:
[0001]    The present application claims priority under 35 U.S.C. 119 and 35 U.S.C. 365 to Korean Patent Application No. 10-2008-0017605 (filed on Feb. 27, 2008), which is hereby incorporated by reference in its entirety. 
       BACKGROUND 
       [0002]    The present disclosure relates to an ice making assembly for a refrigerator and a method for controlling the ice making assembly. 
         [0003]    Refrigerators are domestic appliances used for storing foods by refrigerating or freezing the foods. Recently, various kinds of refrigerators have been introduced into the market. Examples of recent refrigerators include: a side by side type refrigerator in which a refrigerator compartment and a freezer compartment are disposed on the left and right sides; a bottom freezer type refrigerator in which a refrigerator compartment is disposed above a freezer compartment; and a top mount type refrigerator in which a refrigerator compartment is disposed under a freezer compartment. 
         [0004]    Furthermore, many of the recently introduced refrigerators have a home bar structure. These permit users to access foods or drinks disposed inside a refrigerator compartment through the home bar (i.e., a relatively small access portal) without having to open the larger refrigerator door. 
         [0005]    Refrigerators typically employ a number of refrigeration-cycle components. These include a compressor, a condenser, and an expansion member disposed inside the refrigerator. An evaporator is typically disposed on the backside of the refrigerator main body. 
         [0006]    In addition, an ice making assembly may be provided. The ice making assembly may be mounted in the freezer compartment, the refrigerator compartment, on the freezer compartment door, or on the refrigerator compartment door. 
         [0007]    To satisfy consumers&#39; increasing demands for transparent ice, ice making assemblies are now being designed to produce ice that is very clear and not cloudy. Accordingly much research has been conducted on ice making assemblies that can provide transparent ice. 
         [0008]    Known related art ice making assemblies generally employ an additional water tank disposed at a predetermined side of the refrigerator. It is connected to the ice making tray through a tube which supplies water to the ice making tray. Alternatively, the ice making tray may be directly connected to a tap (i.e., external water source) through a tube. 
       SUMMARY 
       [0009]    Embodiments provide an ice making assembly for a refrigerator that can produce transparent ice easily and maintain the amount of water supplied for making ice at a constant level for each ice making cycle, and a method for controlling the ice making assembly. 
         [0010]    Embodiments also provide an ice making assembly for a refrigerator in which the supply of water is automatically interrupted to prevent overflowing when the water supplied to an ice making tray reaches a set level, and a method for controlling the ice making assembly. 
         [0011]    Embodiments also provide an ice making assembly for a refrigerator that can control the amount of water supplied at a constant level regardless of water pressure variations, and a method for controlling the ice making assembly. 
         [0012]    Embodiments also provide an ice making assembly for a refrigerator that can reduce unnecessary power consumption by rapidly detecting a water supply error when water is not supplied to the ice making tray due to, for example, a malfunction of a water supply valve, and a method for controlling the ice making assembly. 
         [0013]    In accordance with one aspect of the present invention, the capabilities set forth below may be achieved by an ice making assembly that comprises, among other things, a tray configured to receive water. The tray includes a plurality of ice recesses. The assembly also comprises a water level sensor positioned in the tray, where the water level sensor includes a first electrode and a second electrode, the first electrode positioned lower in the tray relative to the second electrode, and wherein an electrical connection between the first and the second electrode occurs upon the water level reaching the second electrode. 
         [0014]    In accordance with another aspect of the present invention, the capabilities set forth below may be achieved by a refrigerator ice making assembly control method, where the ice making assembly includes a tray having a plurality of ice recesses and a water level detection sensor that includes a first and a second electrode. The method involves supplying water to the ice recess and allowing the water level in the ice recesses to reach the second electrode, wherein the first and second electrodes are vertically aligned and wherein the first electrode is positioned lower in the tray relative to the second electrode. The method then involves detecting an electrical connection between the first electrode and the second electrode as a result of the water coming into contact with the second electrode. Finally, the method involves determining that the water level has at least reached the second electrode if an electrical connection between the first and the second electrodes is detected. 
         [0015]    The ice making assembly and the method of controlling the ice making assembly according to the present disclosure are capable of more easily making transparent ice. This will be clear from the following disclosure. 
         [0016]    In addition, the ice making assembly and the method of controlling the ice making assembly are capable of maintaining the level of the supplied water at a constant level for each ice making cycle regardless of water pressure variations. Therefore, water overflow, the freezing of water that has overflowed, and overflow water escaping from the refrigerator can be prevented. Even if varying amounts of water remain in the ice recesses of the tray following an ice making cycle, the desired water level can still be achieved. 
         [0017]    Moreover, when water is not supplied to the tray due to, for example, a malfunction in the water supply valve, the present invention is capable of rapidly detecting and reducing power consumption. 
         [0018]    In addition, the ice making assembly is capable of detecting the level of water using existing components without using any additional device so that the manufacturing costs of the ice making assembly can be reduced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIGS. 1 and 2  are perspective views illustrating an ice making assembly structure for a refrigerator according to exemplary embodiments of the prevent invention. 
           [0020]      FIG. 3  is a perspective view illustrating an ice making assembly according to exemplary embodiments of the present invention. 
           [0021]      FIG. 4  is a perspective view illustrating the ice making assembly prior to ice being transferred to a container. 
           [0022]      FIG. 5  is a perspective view illustrating a tray of the ice making assembly according to exemplary embodiments of the present invention. 
           [0023]      FIG. 6  is a perspective view illustrating a water level sensor of the ice making assembly according to exemplary embodiments of the present invention. 
           [0024]      FIG. 7  is a circuit diagram of an exemplary water level sensor, according to exemplary embodiments of the present invention. 
           [0025]      FIG. 8  is a sectional view taken along line I-I′ of  FIG. 5  which illustrates the increasing level of water supplied to the tray of the ice making assembly according to exemplary embodiments. 
           [0026]      FIG. 9  is a graph illustrating voltage variations in a circuit where water level is increasing. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0027]    Hereinafter, an ice making assembly for a refrigerator will be described in detail according to exemplary embodiments of the present disclosure with reference to the accompanying drawings. In the following description, an ice making assembly is mounted at a freezer compartment door. However, the ice making assembly can alternatively be mounted at other places such as the freezer compartment, the refrigerator compartment, and on the refrigerator compartment door. 
         [0028]      FIGS. 1 and 2  are perspective views illustrating an ice making assembly structure for a refrigerator according to exemplary embodiments of the present invention. As shown, an ice making assembly  20  is mounted on the backside of a door  10 , and the backside of the door  10  is recessed to form an ice making assembly space  11  for accommodating the ice making assembly  20 . A cooling air supply hole  111  is formed at a side of the ice making assembly space  11  for allowing the inflow of cooling air from an evaporator (not shown), and a cooling air discharge hole  112 , formed in the side of the ice making assembly space  11 , for allowing the cooling air to be discharged from the ice making assembly space  11  to the evaporator. 
         [0029]    The ice making assembly  20  is mounted at an upper portion of the ice making assembly space  11 , and a container  30  is mounted under the ice making assembly  20  to store ice made by the ice making assembly  20 . The ice making assembly  20  is protected by an ice making cover  31 . In addition, owing to the ice making cover  31 , ice, when separating from the ice making assembly  20 , does not spill outward. It instead falls cleanly into the container  30 . 
         [0030]      FIG. 3  is a perspective view illustrating the ice making assembly  20  according to exemplary embodiments of the present invention, and  FIG. 4  is a perspective view illustrating the ice making assembly  20  just before ice is transferred to the container  30 . As shown, the ice making assembly  20  includes a tray  21  having a plurality of ice recesses  211  for making ice in a predetermined shape; a plurality of fins  24  rotatably and movably stacked above the tray  21 ; a plurality of rods  23  configured to be inserted into the ice recesses  211  through the fins  24 ; an ice ejecting heater  25  provided at the lowermost fin  24 ; a supporting plate  27  configured to support the ice ejecting heater  25 , the fins  24 , and the rods  23  as one unit; a water supply part  26  disposed at an end of the tray  21 ; and a control box  28  disposed at the opposite end of the tray  21 . 
         [0031]    A heater (not shown) is mounted at the bottom of the tray  21  to maintain the tray  21  at a temperature higher than freezing. A supporting lever  271  extends from the front of supporting plate  27 , and a hinge  272  is formed at one end of the supporting plate  27 . During an ice making operation, as shown in  FIG. 4 , ice (I) having a shape corresponding to the shape of the ice recesses  211  are formed around the rods  23 . 
         [0032]    Referring again to  FIG. 3 , a cam  29  and a driving motor for actuating the cam  29  are disposed inside the control box  28 . The hinge  272  is connected to the cam  29  so that the hinge  272  can be lifted and rotated by the movement of cam  29 . The ice ejecting heater  25  may be form in the shape of a plate and it contacts the rods  23 . Alternatively, the ice ejecting heater  25  may be contained inside the rods  23 . The supporting plate  27  also serves as a top for tray  21  such that water supplied to the tray  21  is indirectly cooled by the cooling air supplied to the ice making assembly space  11 . 
         [0033]    Hereinafter, the ice making and ice ejecting operation of the ice making assembly  20  will be described. First, the aforementioned heater attached to tray  21  maintains the tray  21  at a temperature higher than 0° C. This facilitates the process of making transparent ice in the ice making assembly  20  as described in greater detail below. 
         [0034]    More particularly, because water is rapidly frozen by cooling air supplied by an evaporator in accordance with known ice making assemblies, air dissolved in the water is trapped in and cannot be discharged from the water during freezing. Consequently, the water freezes with gas dissolved in the water, and this results in cloudy (i.e., non-transparent) ice. 
         [0035]    Accordingly, the tray  21  in accordance with exemplary embodiment of the present invention is maintained at a temperature higher than freezing, thus the water freezes slowly so that air dissolved in the water has time to escape the water before the water is frozen. The resulting ice is transparent, not cloudy. 
         [0036]    Towards the beginning of the ice making process, the rods  23  are inserted in the ice recesses  211  of the tray  21 . Water is then supplied to the tray  21 , and the freezing operation begins after the supply of water is completed. The freezing operation begins when cooling air is supplied to the ice making assembly space  11 . The temperature of the fins  24  is then reduced to a temperature below freezing by the supplied cooling air. The temperature of the rods  23  is also reduced to a temperature below freezing through conduction with the fins  24 . A Portions of each rod  23  is submerged in the water; therefore, the water is gradually frozen beginning with the water located closest to the rods  23 . Eventually, water located further from the rods  23  also freeze. 
         [0037]    After the water freezing operation is completed, cam  29  is rotated to move the rods  23  out of the ice recesses  211 . That is, the cam  29  is rotated to lift the rods  23 , and after the ice (I) is removed from the ice recesses  211 , the cam  29  is further rotated causing the rods  23  to tilt at a predetermined angle. More specifically, the rotation of the cam  29  causes the hinge  272  to rotate. The rotation of the hinge  272 , in turn, causes the rods  23  to tilt at a predetermined angle. When the rods  23  are tilted at a predetermined angle, as shown in  FIG. 4 , the ice ejecting heater  25  begins operating. 
         [0038]    Here, whether freezing of the water is completed may be determined by a predetermined elapse of time from the start of the water freezing operation. That is, if a predetermined time passes after the start of the freezing operation, it may be determined that the water freezing operation is complete. 
         [0039]    Alternatively, the cam  29  may be rotated to lift the rods  23  to a predetermined height after a predetermined period of time elapses from the start of the water freezing operation. Here, the predetermined height means a height at which ice attached to the rods  23  is not yet fully separated from the ice recesses  211 . If, after the rods  23  are lifted, the amount of water remaining in the ice recesses  211  is equal to or less than a predetermined amount of water, it may be determined that the water freezing operation is complete. The amount of water remaining in the ice recesses  211  can be detected using a water level sensor mounted on the tray  21 . On the other hand, if the amount of water remaining in the ice recesses  211  is greater than the predetermined amount, the rods  23  may be are moved downward to the original position to continue the water freezing operation. The water sensor will be described later with reference to the accompanying drawings. 
         [0040]    After the water freezing operation has been completed, and the rods  23  have been lifted and rotated as explained above, the ice ejecting heater  25  is operated. This causes the temperature of the rods  23  to increase. Eventually, the temperature of the rods causes the ice pieces (I) to separate from the rods  23 . The separated ice pieces (I) then falls cleanly into the container  30 . 
         [0041]    Further in accordance with the exemplary embodiments of the present invention, the position of the rods relative to the ice recesses may be user adjustable. For example, the user may have an option to select the size of the ice that is produced by the ice making assembly, through the use of a selection button and a corresponding control circuit. The position of the rods relative to the ice recesses is then adjusted as a function of the user&#39;s selection. If the user wants the ice making assembly to produce small sized ice, it will be understood, from the preceding disclosure that the position of the rods will be automatically set relative far down in the ice recesses. Accordingly, when water is supplied to the tray, a relatively small amount of water will be required to achieve an electrical connection between the rods and the tray. When the connection is achieved, the control circuit, such as the control circuit illustrated in  FIG. 7 , stops the water supply and smaller sized ice is ultimately produced as less water was used to fill the tray. If the user instead chooses medium or large sized ice, the rods will not be positioned as far down in the ice recesses as was the case with smaller sized ice, thus allowing a greater amount of water to be supplied to the tray, resulting in larger sized ice. 
         [0042]      FIG. 5  is a perspective view illustrating the tray  21  of the ice making assembly  20  according to an embodiment. As shown, tray  21  includes ice recesses  211 . Grooves  213  having a predetermined depth are formed between the ice recesses  211 , allowing water to pass there through to evenly fill all of the ice recesses  211 . 
         [0043]    A guide  212  is formed at one end of the tray  21  to guide water supplied to the tray  21  and into the ice recesses  211 . Therefore, water supplied through the water supply part  26  is guided into the ice recesses  211  by guide  212 . Water is supplied to the ice recesses  211  gradually from the ice recess  211  closest to the guide  212  to the ice recess  211  farthest from the guide  212 . 
         [0044]    A water level sensor  40  is mounted at one side of the ice recess  211 , preferably opposite to the guide  212 . Further, a temperature sensor  50  is mounted at one side of the tray  21  to maintain the tray  21  at a constant temperature. A tray heater (not shown) is installed at the tray  21  or, alternatively, integrated into the tray  21 . 
         [0045]      FIG. 6  is a perspective view illustrating the water level sensor  40  of the ice making assembly  20  according to exemplary embodiments of the present invention. As shown, the water level sensor  40  may be mounted at one side of the ice recess  211  as described above. The water level sensor  40  comprises a number of electrodes that are employed to detect the water level in the ice recesses. In general, this is achieved by applying a voltage to the electrodes and measuring current flowing through the water, between the electrodes. 
         [0046]    More specifically, the water level sensor  40  includes a plurality of electrodes. In addition, output lines  41  extend from the electrodes and are connected to a refrigerator control unit (not shown). 
         [0047]    In this exemplary embodiment, the water level sensor  40  includes three electrodes: Electrode A, a middle electrode B, and a lower electrode C. When the water level sensor  40  is attached to the tray  21 , electrode A may be located at a position slightly lower than the highest expected water level. Electrode C may be located at a position just higher than the bottom of the tray  21  (i.e., the ice recesses  211 ). For example, electrode C may be located at a height that corresponds with the bottom of the groove  213 . 
         [0048]    An exemplary operation of the water level sensor  40  during a water supplying operation will now be explained.  FIG. 7  is an exemplary circuit for implementing the water level sensor  40  according to exemplary embodiments of the present invention. As shown, the electrodes A, B, and C of the water level sensor  40  generate sensor signals according to the water level. The sensor signals are then transmitted to a control unit (MICOM). 
         [0049]    In this exemplary embodiment, electrode C is grounded, and the electrodes A and B are electrically connected to electrode C depending on the level of supplied water. Also as shown, the circuit includes an output terminal (a) which generates an on-signal associated with electrode A. Output terminal (b) generates an on-signal associated with electrode B. The output terminals (a) and (b) are connected to the control unit. Comparators (c) are provided in the circuit for comparing a reference voltage Vcc to a voltage V which is generated when electrode A and/or B is connected to electrode C by virtue of the water level. 
         [0050]    In the above-described circuit, as water is supplied to the tray  21 , the level of water in the ice recess  211  increases. If the water level is lower than electrode C or located between electrodes B and C, neither output terminal (a) or (b) will generate an output signal because the electrode C is grounded. In this case, both electrode A and B are open circuit with electrode C. This results in a low voltage output at the corresponding comparator (C). This, in turn, prevents the corresponding output terminal (a) and/or (b) from generating an on-signal. 
         [0051]    If the water level of the ice recess  211  increases to the height sufficient to electrically connect electrode B to the electrode C, then corresponding output terminal (b) generates an on-signal. That is, if electrodes B and C are electrically connected to each other, by virtue of the water, the voltage of the output terminal (b) decreases steeply as current flows through the transistor, thus generating an on-signal. The control unit detects this on-signal and determines that the water level has at least reached the height of electrode B. 
         [0052]    If the water level of the ice recess  211  increases to a height sufficient to electrically connect electrode A to electrode C, then the corresponding output terminal (a) similarly generates an on-signal. The control unit can then detect the on-signal from output terminal (a) and determine that the water level has at least reached the height of electrode A. 
         [0053]      FIG. 8  is a sectional view taken along line I-I′ of  FIG. 5 . More specifically,  FIG. 8  illustrates the increasing level of water supplied to tray  21  of the ice making assembly  20 , in relation to electrodes A, B and C, according to exemplary embodiments of the present invention.  FIG. 9  is a graph illustrating a voltage variation that is realized across the output terminal (b) when the level of water reaches a height sufficient to electrically connect electrode B to electrode C. 
         [0054]    With further reference to  FIGS. 8 and 9 , until the level of water supplied to the ice recess  211  of the tray  21  increases to the height of electrode B, the voltage of the circuit (i.e., the output voltage associated with output terminal (b)) is kept substantially at a constant level Vcc. However, when the level of water increases to the height of electrode B, the voltage of the circuit (i.e., across the output terminal (b) decreases from Vcc to V, where V is a substantially lower voltage level. The control unit detects this voltage drop (Vcc−V) and uses this to determine that the water level has reached a height in the tray  21  which is at least as high as electrode B. 
         [0055]    In contrast, when the ice recess  211  is not filled with water, there is no electrical connection between electrodes B and C, nor between electrodes A and C. The corresponding Comparator (c) outputs a low voltage, the corresponding output terminal is biased OFF and the voltage realized at the output terminal is the source voltage V. 
         [0056]    However, when water is supplied to the ice recess  211  to the height of electrode B, a relatively low resistance forms between electrodes B and C due to the supplied water. Since the resistance of water is lower than that of air, the voltage of the circuit (i.e., the voltage across the output terminal(b)) drops as current flows from the source to the drain of the transistor associated with output terminal (b). The control unit detects the voltage drop and uses this to determine that the water level has at least reached electrode B. 
         [0057]    If the level of water further increases to the height of electrode A, the same voltage variation (Vcc−V) is observed at output terminal (a) as shown in  FIG. 9 . That is, if the level of water reaches the height of electrode A, a voltage drop occurs at the output terminal (a). The control unit detects the voltage drop at the output terminal (a) and uses this to determine that the water level has at least reached the height of electrode A. 
         [0058]    Thus, when the level of water reaches the height of electrode B, a voltage drop is detected at the output terminal (b), and when the level of water increases to the height of the electrode A, a voltage drop is detected at the output terminal (a). 
         [0059]    Owing to the above-described structure, the amount of water supplied to the tray  21  can be precisely detected, and thus water overflow can be prevented, the freezing of overflowing water can be prevented, and water escaping from the refrigerator can be prevented. 
         [0060]    Furthermore, if an expected level of water is not detected within a predetermined time after a water supply valve is opened, the control unit can determine that there is a water supply error, and suspend the water freezing operation. Therefore, unnecessary heater operation and the unnecessary supplying of cooling air can be prevented. 
         [0061]    Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments 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.