Patent Abstract:
An ice making assembly for a refrigerator and a method for controlling the ice making assembly are provided. The ice making assembly and the method of controlling the ice making assembly provides a constant amount of water supply for each ice making cycle regardless of environmental conditions such as the varying water supply pressure of different installation locations. Furthermore, overflowing can be prevented during water supply with the use of a capacitance water level sensor.

Full 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. 10-2008-0017608, filed Feb. 27, 2008 and Korean Application No. 10-2008-0017609, filed Feb. 27, 2008, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND 
     The present disclosure relates to an ice making assembly for a refrigerator and a method for controlling the ice making assembly. 
     Refrigerators are domestic appliances used for storing foods in a refrigerated or frozen state. 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 in 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. 
     Furthermore, many of recently introduced refrigerators have a structure that allows a user to access food or drink disposed inside a refrigerator compartment through an alternate access point without having to open a primary refrigerator compartment door. A compressor, a condenser, and an expansion member are disposed inside a refrigerator, and an evaporator is disposed on the backside of a refrigerator main body, as refrigeration-cycle components of the refrigerator. 
     In addition, an ice making assembly can be provided inside the refrigerator. The ice making assembly may be mounted in a freezer compartment, a refrigerator compartment, a freezer compartment door, or a refrigerator compartment door. 
     To satisfy consumers&#39; increasing demands for transparent ice, much research has been conducted on ice making assemblies that can provide transparent ice. 
     In an ice making assembly of the related art, an additional water tank is disposed at a predetermined side of a refrigerator and is connected to an ice making tray through a tube to supply water to the ice making tray, or a tap of an external water source is directly connected to the ice making tray through a tube. 
     SUMMARY 
     The disclosed embodiments provide an ice making assembly for a refrigerator that can produce transparent ice easily and maintain the amount of water supplied to make ice at a constant level for each ice making cycle, and a method for controlling the ice making assembly. 
     The disclosed embodiments also provide an ice making assembly for a refrigerator in which a supply of water is automatically interrupted for preventing overflow when the water supplied to an ice making tray reaches a set level, and a method for controlling the ice making assembly. 
     The disclosed embodiments also provide an ice making assembly for a refrigerator that can maintain the amount of supplied water at a constant level regardless of water pressure variations occurring at the location the ice-making assembly is installed, and a method for controlling the ice making assembly. 
     The disclosed embodiments also provide an ice making assembly for a refrigerator that can reduce unnecessary power consumption by immediately detecting a water supply error when water is not supplied to an ice making tray due to, for example, malfunctioning of a water supply valve, and a method for controlling the ice making assembly. 
     The disclosed embodiments provide an ice making assembly for a refrigerator and a method for controlling the ice making assembly as follows. 
     In one embodiment, there is provided an ice making assembly for a refrigerator, the ice making assembly including: a tray comprising a water supply part and a plurality of ice recesses; a plurality of fins above the tray; a plurality of rods inserted in the ice recesses through the fins and configured to be lifted and titled together with the fins after a freezing operation; and a water level sensor at one of the ice recesses. 
     In another embodiment, there is provided an ice making assembly for a refrigerator, the ice making assembly including: a tray comprising a water supply part and a plurality of ice recesses; a plurality of fins above the tray; a plurality of rods inserted in the ice recesses through the fins and configured to be lifted and titled together with the fins after a freezing operation; and a water level sensor at one of the ice recesses, wherein the water level senor includes: an earth electrode at a lowermost side; an intermediate level electrode disposed at a position upward from the earth electrode for detecting an intermediate water level; and a full level electrode disposed at a position upward from the intermediate level electrode for detecting a full water level. 
     In another embodiment, there is provided a method for controlling an ice making assembly of a refrigerator, the method including: disposing a rod vertically at an upper side of a tray in which an ice recess is formed; moving the rod down into the ice recess; supplying water to the ice recess; allowing the water to reach a height at or below which an earth electrode and at least one electrode of a water level sensor are located; and detecting a level of the water by detecting a capacitance variation between the earth electrode and the at least one electrode. 
     By using the ice making assembly for a refrigerator and the method of controlling the ice making assembly according to the present disclosure, transparent ice can be easily made. 
     Furthermore, water can be supplied at a constant level for each ice making cycle regardless of water pressure variations at the installed location of the refrigerator. Therefore, water supply overflow, freezing of overflowed water in the refrigerator, and leakage of overflowed water from the refrigerator can be prevented. 
     Furthermore, although different amounts of water remain in the ice recesses of the tray, water can be supplied to the ice recesses at an equal level. 
     Moreover, when water is not supplied to the tray due to malfunctioning of a water supply valve, such a situation can be immediately detected for reducing unnecessary power consumption. 
     In addition, the ice making assembly can detect the level of water using existing components without the need for an additional device. This reduces the manufacturing costs of the ice making assembly. 
     The details of one or more embodiments 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 
         FIGS. 1 and 2  are perspective views illustrating an ice making assembly structure for a refrigerator according to an embodiment of the invention. 
         FIG. 3  is a perspective view illustrating an ice making assembly according to an embodiment of the invention. 
         FIG. 4  is a perspective view illustrating the ice making assembly, according to an embodiment of the invention, just before ice is transferred to a container. 
         FIG. 5  is a perspective view illustrating a tray of the ice making assembly according to an embodiment of the invention. 
         FIG. 6  is a perspective view illustrating a water level sensor of the ice making assembly according to an embodiment of the invention. 
         FIG. 7  is a sectional view taken along line I-I′ of  FIG. 5  for illustrating the increasing level of water supplied to the tray of the ice making assembly according to an embodiment of the invention. 
         FIG. 8  is a graph illustrating variations of circuit capacitance with respect to the level of water in the ice making assembly of  FIG. 7 . 
         FIGS. 9 to 12  are views for illustrating variations of the level of water supplied to the tray of the ice making assembly according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, an ice making assembly for a refrigerator will be described in detail according to the disclosed 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 be mounted at other places such as a freezer compartment, a refrigerator compartment, and a refrigerator compartment door without departing from the scope of the invention. 
       FIGS. 1 and 2  are perspective views illustrating an ice making assembly structure for a refrigerator according to an exemplary embodiment of the invention. 
     Referring to  FIGS. 1 and 2 , an ice making assembly  20  may be mounted on the backside of a door  10 , and the backside of the door  10  may be recessed to form an ice making space  11  for accommodating the ice making assembly  20 . A cooling air supply hole  111  may be formed at a side of the ice making space  11  for allowing inflow of cooling air from an evaporator (not shown), and a cooling air discharge hole  112  may be formed in the side of the ice making space  11  to allow the cooling air from the ice making space  11  to flow back the evaporator. 
     In detail, the ice making assembly  20  may be mounted at an upper portion of the ice making space  11 , and a container  30  may be mounted under the ice making assembly  20  to store ice made by the ice making assembly  20 . The ice making assembly  20  may be protected by an ice making cover  31 . The ice making cover  31  may also provide guidance for the ice separated from the ice making assembly  20  so that it follows a path directly to the container  30 . 
       FIG. 3  is a perspective view illustrating the ice making assembly  20  according to an embodiment of the invention, and  FIG. 4  is a perspective view illustrating the ice making assembly  20 , according to an embodiment of the invention, just before ice is transferred to the container  30 . 
     Referring to  FIGS. 3 and 4 , the ice making assembly  20  of the current embodiment may include: a tray  21  having a plurality of ice recesses  211  for making ice in a predetermined shape; a plurality of fins  24  stacked above the tray  21  and capable of vertical and rotational movement; 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 of the plurality of fins  24 ; a supporting plate  27  configured to support the ice ejecting heater  25 , the remainder of the plurality of 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 another other end of the tray  21 . A heater (not shown) may be mounted at the bottom of the tray  21  to maintain the temperature of the tray  21  at a temperature above freezing. A supporting lever  271  may extend from a front end of the supporting plate  27 , and a hinge  272  may be disposed at an end of the supporting plate  27 . During an ice making operation, as shown in  FIG. 4 , ice cubes (I) having a shape corresponding to the shape of the ice recesses  211  may be formed around the rods  23 . 
     A cam  29  and a driving motor may be disposed inside the control box  28 . The driving motor may drive a rotational movement of the cam  29 . The hinge  272  is coupled to the cam  29  so that the hinge  272  can be used and rotated by rotating the cam  29 . The ice ejecting heater  25  may have a plate-like shape and may contact the rods  23 . Alternatively, the ice ejecting heater  25  may be embedded within the rods  23 . The supporting plate  27  may act to close an open-top of the tray  21  ( FIG. 3 ) such that water supplied to the tray  21  is indirectly cooled by cooling air supplied to the ice making space  11  and flowing about the fins  24  and rods  23 . 
     Hereinafter, ice making and ice ejecting operations of the ice making assembly  20  will be described. 
     First, the heater attached to the tray  21  may be operated to maintain the tray  21  at a temperature higher than 0° C., to create an environment that can make transparent ice in the ice making assembly  20 . 
     When water is rapidly frozen by cooling air supplied from an evaporator, air dissolved in the water cannot escape from the water before it is frozen. Thus, when water is frozen together with the gas that is trapped inside the water, the resulting ice is not transparent. 
     However, in the ice making assembly  20  of the disclosed exemplary embodiments, the tray  21  may be maintained at a temperature above freezing so that the water freezes slowly, starting at the freezing rod  23 . The air in the water is then able to escape before the water is completely frozen. Thus, transparent ice, which is preferred by the user, may be produced. 
     According to one embodiment, either before or after water is supplied to the tray  21 , the rods  23  may be inserted into the ice recesses  211  of the tray  21 , and a freezing operation may be started. In general, the freezing operation may be started after a predefined volume of water is added to the tray  21 . The freezing operation may be started by supplying cooling air to the ice making space  11 . The temperature of the fins  24  may then be reduced to below the freezing temperature by conduction heat transfer with the supplied cooling air. The temperature of the rods  23  may also be reduced to below the freezing temperature by conduction heat transfer with the fins  24 . Portions of the rods  23  inserted in the ice recesses  211  are submerged in the water. Therefore, the water is gradually frozen starting from a region closest to the rods  23 . As the water freezes, the frozen region becomes attached to the rods  23 . The freezing of the water then proceeds outwardly from the outer surfaces of the rods  23  to the inner surfaces of the ice recesses  211 . 
     After the freezing of the water is completed, the cam  29  may be rotated to move the rods  23 , and the ice cubes formed thereon, out of the ice recesses  211 . That is, the cam  29  is rotated to lift the rods  23  vertically upward, thus the formed ice cubes (I) may be completely removed from the ice recesses  211 . The cam  29  may be further rotated to tilt the rods  23  to a predetermined angle. 
     The completion of the freezing of the water may be determined by the passage of a predetermined amount of time. More specifically, if a predetermined time passes after the start of the freezing of the water, this may determine that the freezing is completed. 
     Another method of determining the completion of freezing, involves lifting rods  23 , via cam  29 , to a predetermined height after a predetermined time from the start of freezing. The predetermined height may be a height at which ice attached to the rods  23  is not yet fully separated from the ice recesses  211 . Once the rods  23  are lifted, the amount of water remaining in the ice recesses may be detected. In one embodiment, the amount of water remaining in the ice recesses  211  may be detected using a water level sensor mounted on the tray  21 . If the amount of water remaining in the ice recesses  211  is equal to or less than a predetermined amount, it may be determined that the freezing is completed. 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 moved down to their original positions to continue the freezing of the water. The water sensor will be described later with reference to the accompanying drawings. As described above, after the freezing of the water is completed, the cam  29  may be rotated such that it moves the rods  23  vertically upward out of the ice recesses  211 . After ice cubes (I) are completely removed from the ice recesses  211 , the cam  29  is further rotated to effect rotation of the rods  23 . More specifically, the hinge  272  is rotated by the cam  29  to rotate the rods  23  to a predetermined angle. 
     Once the rods  23  are rotated to the predetermined angle, such as the angle shown in  FIG. 4 , the ice ejecting heater  25  may be operated. 
     When the ice ejecting heater  25  is operated, the temperature of the rods  23  increases, and thus the ice cubes (I) are separated from the rods  23 . The separated ice cubes (I) may then fall into the container  30 . 
       FIG. 5  is a perspective view illustrating the tray  21  of the ice making assembly  20  according to an embodiment of the invention. 
     As illustrated in  FIG. 5 , the ice recesses  211  may be arranged in the tray  21  of the ice making assembly  20 . Channels  213  having a predetermined depth may be formed between the ice recesses  211 . 
     Water can travel between neighboring ice recesses  211  through the channels  213 . Bottoms of the channels  213  are spaced apart from bottoms of the ice recesses  211 . 
     A guide  212  may be formed at an end portion of the tray  21  to guide water supplied from the water supply part  26  to the tray  21  and to the ice recesses  211 . Water may be supplied to the ice recesses  211  closest to the guide  212  and may gradually travels to the ice recess  211  farthest from the guide  212 . 
     A water level sensor  40  may be mounted at a side of the ice recess  211  farthest from the guide  212 , e.g., at a side of the ice recess located at an end of the tray  21  opposite to the guide  212 . Further, a temperature sensor  50  may be mounted at a side of the tray  21  and may be used in conjunction with a subassembly to maintain the tray  21  at a constant temperature. A tray heater (not shown) may be installed at the tray  21 . The tray heater may be installed at the tray  21  in an embedded manner or attached manner. 
       FIG. 6  is a perspective view illustrating the water level sensor  40  of the ice making assembly  20  according to an embodiment of the invention. 
     Referring to  FIG. 6 , the water level sensor  40  provided at the ice making assembly  20  according to an embodiment of the present disclosure may be mounted at the side of the ice recess  211  as described above. The water level sensor  40  is a capacitive sensor capable of detecting the existence of an object by sensing the capacitance of the object using multiple electrodes disposed at a side of the object. The capacitance water level sensor  40  is a more reliable method of detecting water levels as it is not subject to instantaneous, temporary water level changes, for example caused by opening and closing the refrigerator door housing the ice making device. 
     In the disclosed embodiment electrodes are provided at a side of ice recess  211  so that the level of water supplied to the tray  21  can be detected using the water level sensor  40 . In more detail, as illustrated in  FIG. 6 , the water level sensor  40 , of the exemplary embodiment, includes a plurality of electrodes, and output terminals  41 . The output terminals  41  may extend from the electrodes and may connect to the control unit  45 , which may be a control unit for operation of the refrigerator in general. The plurality of electrodes are covered with a waterproof layer  42  ( FIGS. 6 and 7 ) so that water cannot function as a conductor having resistance between the electrodes. Hereinafter, an explanation will be given of an exemplary embodiment where the water level sensor  40  includes three electrodes. 
     In detail, the water level sensor  40  includes an upper electrode A, a middle electrode B, and a lower electrode C. When the water level sensor  40  is attached to the tray  21 , the electrode A may be located at a position slightly lower than the highest water level of the ice recess  211 , and the electrode C may be located at a position higher than the bottom of the ice recess  211 . For example, the electrode C may be located at the same height as the bottom of the channel  213 , which is the channel through which water can flow from one ice recess to a neighboring ice recess. As described above, the electrodes A, B, and C cannot make direct contact with water due to the waterproof layer  42 . Electrode C is grounded, and an electric charge can be stored between the electrodes B and C or the electrodes A and C according to the level of water. 
       FIG. 7  is a sectional view taken along line I-I′ of  FIG. 5  for illustrating the increasing level of water supplied to the tray of the ice making assembly according to an embodiment of the invention, and  FIG. 8  is a graph illustrating variations of circuit capacitance with respect to the level of water in the ice making assembly of  FIG. 7 . Referring to  FIGS. 7 and 8 , when the ice recess  211  of the tray  21  is not filled with water, the capacitance between electrodes A and C or electrodes B and C is the capacitance (Ca) of air. In this state, no signal is transmitted to the control unit  45  through the output terminals  41 . Similarly, when the level of water in the ice recess  211  is between the electrodes B and C, no signal is transmitted to the control unit  45  through the output terminals  41  because the electrode C is grounded and the water level has not yet reached electrode B. 
     As water is supplied to the tray  21  and the water in ice recess  211  reaches electrode B, the capacitance between the electrodes B and C changes. That is, the capacitance between the electrodes B and C changes from the capacitance Ca of air to the capacitance (Cw) of water. Accordingly, a sensor signal is sent to the control unit  45  through the output terminal  41  of the electrode B. 
     As shown  FIG. 8 , since the capacitance Cw of water is greater than the capacitance Ca of air, the capacitance between the electrodes B and C will change when the level of water reaches the height of the electrode B. Then, the control unit  45  detects the variation of the capacitance and determines that the level of water has reached the height of the electrode B. 
     If the level of water further increases to the height of electrode A, the capacitance between electrodes A and C will change, similar to the change described above with respect to electrodes B and C. That is, the medium between electrodes A and C changes from air to water, and thus the capacitance between electrodes A and C changes. A sensor signal corresponding to the capacitance change is sent to the control unit  45  through the output terminal  41  (connected to the electrode A). The control unit  45  thus may determine that the level of water has reached the height of electrode A. 
       FIGS. 9 to 12  illustrate water level variations of the tray  21  of the ice making assembly  20  when water is supplied to the tray  21 . For ease of illustration, rods  23  are not depicted in  FIGS. 9 to 12 . It will be understood, depending on whether water is added before or after rods  23  are inserted into the ice recesses  211 , that the displacement of water attributable to the rods  23  may be considered in determining the positioning of electrodes A, B, and C. 
     Referring to  FIG. 9 , after a predetermined amount of time has passed after the water supply has begun, the level of water in the tray  21  at a side of the tray  21  adjacent the guide  212  is different from a water level at a side of the tray  21  opposite to the guide  212 . 
     In more detail, water is first filled in the ice recess  211 A closest to the guide  212 . When the level of water in the closest ice recess  211 A exceeds the bottom of the channel  213 , the supplied water then travels to the adjacent ice recess  211 B. However, a large amount of water is not transferred to the neighboring ice recesses all at once due to the narrow width of the channel  213  and the surface tension of the water. Therefore, at the beginning of the water supply, the level of water in the ice recess  211 A closest to the guide  212  is considerably different from the level of water in the ice recess  211 C, which is where the water level sensor  40  is installed. The ice recess  211 C maybe the ice recess farthest from the guide  212 . 
     As illustrated in  FIG. 9 , at the moment when the level of water is detected at electrode B, the level (a) of water in the ice recess  211 A, differs greatly from the level (b) of water in the ice recess  211 C (h 1 =a−b, where h 1  is the water level difference). While the water is being supplied, the level of water may slope as illustrated in  FIG. 9 . 
     Given this level difference during water supply, if the water is continuously supplied until it is detected that the ice recess  211 C is filled, oversupply and overflow of at least ice recess  211 A may result. More specifically, if the water supply is stopped only when a full water level is detected in ice recess  211 C, the stabilized final water level may exceed the full water level in ice recesses closer to the guide  212  (such as ice recess  211 A) and cause overflowing of water from the ice tray  21 . This is because the water being supplied to ice recess  211 A from guide  212  does not immediately transfer to the farthest ice recess  211 C. Therefore, to prevent overflow, the water supply is temporarily stopped after water is supplied for a predetermined amount of time sufficient to fill ice recess  211 C to the level of the electrode B. 
     Referring to  FIG. 10 , when the level of water is detected through the electrode B, the water supply is temporarily interrupted. The water level is then stabilized at a level (c) for a predetermined time. In the exemplary illustration of  FIG. 10 , the stabilized water level (c) is higher than the height of the electrode B yet lower than the height of electrode A. The predetermined amount of time that the water supply is stopped may be adjusted according to the pressure of water and the size of the channel  213 . 
     Referring to  FIG. 11 , if water is supplied again after the predetermined amount of time has passed, the level of water changes to result in a water level difference h 2  between ice recess  211 A, closest to guide  212 , and ice recess  211 C, farthest from guide  212 . 
     However, in this example, the water level difference h 2  is not as large as the initial water level difference h 1  because water is re-supplied after the level of water has increased to some degree. That is, since the intermediate water level h 1  is somewhat higher than the bottom of the channel  213 , the water travels between all ice recesses,  211 A through  211 C, more smoothly than it did in the earlier stage of water supply. In addition, the influence of surface tension of water is less as compared with the earlier stage of water supply. 
     After a predetermined amount of time has passed from the start of the re-supply of water, the increasing water level is detected at the electrode A. Then, the supply of water is suspended again to stabilize the water level. 
     As shown in  FIG. 12 , the stabilized final water level (d) is higher than the height of the electrode A. 
     Therefore, by placing the electrode A at a position slightly lower than a full water level, overflowing can be prevented at the end of a water supply operation. 
     In the above-described embodiments, at least two electrodes may be used to detect a capacitance variation between the two electrodes and suspend a supply of water at an intermediate water level. The water supply suspending time may be shortened or extended depending to the position of the electrode B. In the exemplary embodiments and illustrations just described, the spacing between electrodes C and B appears to be equal to the spacing between electrodes A and B; however, the spacing need not be equal. It is within the scope of the invention to adjust the position of, and spacing between, electrodes A, B, and C. The electrodes may thus be spaced apart at regular or irregular intervals. 
     In addition, the amount of water remaining after an ice making operation is complete is determined by the position of electrode B. More specifically, according to an embodiment of the present disclosure, the rod  23  may be slightly lifted after a predetermined amount of time has passed from the start of an ice making operation so as to detect the amount of remaining water. If the amount of remaining water is equal to or smaller than a set amount, it is determined that ice is completely made, and the ice is ejected. If the amount of remaining water is greater than the set amount, the rod  23  is moved down to continue the ice making operation. 
     Thus, the amount of remaining water is determined by the position of the electrode B. If the level of water in the ice recesses  211  is lower than the height of the electrode B, the control unit  45  will determine that there is no water in the ice recess  211 , because the control unit  45  cannot detect a capacitance variation. That is, as the position of the electrode B becomes lower, the amount of remaining water will be reduced, and as the amount of remaining water is reduced, the size of ice pieces will increase. 
     As described above, by using the capacitive sensor  40  capable of sensing capacitance variations, the level of water can be precisely detected, and by supplying water in multiple steps, overflowing of supplied water can be prevented. 
     In addition, if a capacitance variation is not detected after a predetermined amount of time passes after the start of a water supply operation, it may be determined that there is a water supply error. Thus, the supply of cooling air may be suspended to reduce unnecessary power consumption. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments could 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.

Technology Classification (CPC): 5