Patent Publication Number: US-2022228792-A1

Title: Refrigerator and method for controlling the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority under 35 U.S.C. 119 to Korean Patent Application No. 10-2021-0008178, filed in Korea on Jan. 20, 2021, which is hereby incorporated by reference in its entirety. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to a refrigerator and a method for controlling the same. 
     2. Background 
     A refrigerator is a home appliance for storing foods in an internal storage space, which is shield by a door, at a low temperature by low temperature air. For this, the refrigerator is configured to accommodate the stored food in an optimum state by cooling the internal storage space using cold air generated through heat exchange with a refrigerant circulating in a refrigeration cycle. 
     In recent years, refrigerators have become increasingly multi-functional with changes of dietary lives and gentrification of products, and refrigerators having various structures and convenience devices for convenience of users and for efficient use of internal spaces have been released. 
     In addition, the refrigerator is a device to which power is always supplied, and refrigerators having various structures and control methods have been developed to reduce power consumption due to the nature of its use. 
     Korean Patent Registration No. 10-0238059, the subject matter of which is incorporated herein by reference, discloses a method for controlling defrosting of a refrigerator, in which, after a compressor is turned off, when a temperature inside a refrigerating compartment reaches a set temperature, a refrigerating compartment fan is turned on for a predetermined time to prevent frost from being frozen in an evaporator, thereby improving natural defrosting performance. 
     However, when an ice maker is disposed in a region of the refrigerating compartment, cold air for making ice flows from a freezing compartment to the ice maker. A duct through which the cold air flows passes through the region of the refrigerating compartment to affect the temperature inside the refrigerator at the corresponding position. In addition, even during an operation for the natural defrosting, the cold air having a low temperature is penetrated into the refrigerating compartment, and thus, the natural defrosting is not smoothly performed. Accordingly, there is a limitation in that defrosting reliability is deteriorated, as well as power consumption increases. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements, and wherein: 
         FIG. 1  is a front view of a refrigerator according to an embodiment; 
         FIG. 2  is a schematic view of the refrigerator with a door opened; 
         FIG. 3  is a view illustrating an arrangement of an inner case and an ice maker-side cold air passage of the refrigerator; 
         FIG. 4  is a perspective view illustrating a refrigerating compartment door of the refrigerator; 
         FIG. 5  is a cross-sectional view taken along line V-V′ of  FIG. 1 ; 
         FIG. 6  is a block diagram illustrating a flow of a control signal in the refrigerator according to an embodiment; 
         FIG. 7  is a flowchart sequentially illustrating processes of performing a defrosting operation of the refrigerator according to an embodiment; 
         FIG. 8  is a flowchart sequentially illustrating processes of performing a defrosting operation of a refrigerator according to another embodiment; 
         FIG. 9  is a graph illustrating a defrosting operation state when a filler heater does not operate in the refrigerator according to an embodiment; and 
         FIG. 10  is a graph illustrating a defrosting operation state when the filler heater operates in the refrigerator according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Preferred embodiments of the present disclosure will be described below in more detail with reference to the accompanying drawings. It should be noted that when components in the drawings are designated by reference numerals, the same components have the same reference numerals as far as possible even though the components are illustrated in different drawings. Further, in description of embodiments of the present invention, when it is determined that detailed descriptions of well-known configurations or functions disturb understanding of the embodiments of the present invention, the detailed descriptions will be omitted. 
     In addition, the embodiment will be described with an example of a refrigerator configured with a single door for convenience of explanation and understanding, and it should be noted in advance that the present disclosure is applicable to all refrigerators provided with a door. 
     A direction will be defined prior to the explanation. In  FIG. 1 , a direction in which the door is disposed with respect to a cabinet is referred to as a front side, a direction in which the cabinet is disposed with respect to the door is referred to as a rear side, a direction toward a bottom surface on which the cabinet is installed is referred to as a downward side, and a direction away from the bottom surface on which the cabinet is installed is referred to as a upward side. 
       FIG. 1  is a front view of a refrigerator according to an embodiment.  FIG. 2  is a view of the refrigerator with a door opened.  FIG. 3  is a view illustrating an arrangement of an inner case and an ice maker-side cold air passage of the refrigerator. 
     A refrigerator  1  according to an embodiment includes a cabinet  10  defining a storage space and a door  20  opening and closing the storage space of the cabinet  10 . Here, an outer appearance of the refrigerator  1  may be defined by the cabinet  10  and the door  20 . 
     The cabinet  10  may include an outer case  101  defining an outer surface and made of a metal material and an inner case  102  coupled to the outer case  101  to define the storage space in the refrigerator  1  and made of a resin material. In addition, an insulating material is filled between the outer case  101  and the inner case  102  to insulate the storage space inside the cabinet  10 . Also, the storage space may be divided vertically based on a barrier  11  and may be constituted by an upper refrigerating compartment  12  and a lower freezing compartment  13 . 
     A refrigerating compartment evaporator  121  and a freezing compartment evaporator  131  may be provided in the refrigerating compartment  12  and the freezing compartment  13  to independently cool the refrigerating compartment  12  and the freezing compartment  13 , respectively. The refrigerating compartment evaporator  121  and the freezing compartment evaporator  131  may be connected to a compressor  34 , and a refrigerant discharged from the compressor  34  may be branched and supplied to the refrigerating compartment evaporator  121  and the freezing compartment evaporator  131 . 
     A refrigerating compartment fan  122  and a freezing compartment fan  132  may be provided at sides of the refrigerating compartment evaporator  121  and the freezing compartment evaporator  131 , respectively. Thus, air inside the refrigerating compartment  12  may be circulated to pass (or pass through) the refrigerating compartment evaporator  121  by driving of the refrigerating compartment fan  122 , and the heat-exchanged air passing through the refrigerating compartment evaporator  121  may be supplied to the refrigerating compartment  12  to cool the refrigerating compartment  12  to a set temperature. 
     In addition, air inside the freezing compartment  13  may be circulated to pass (or pass through) the freezing compartment evaporator  131  by driving of the freezing compartment fan  132 , and the heat-exchanged air passing through the freezing compartment evaporator  131  may be supplied to the freezing compartment  13  to cool the freezing compartment  13  to a set temperature. 
     The door  20  may include a refrigerating compartment door  21  and a freezing compartment door  22 , which respectively independently open and close the refrigerator compartment  12  and the freezer compartment  13 . The refrigerating compartment door  21  and the freezing compartment door  22  may have structures that are capable of respectively opening and closing the refrigerating compartment  12  and the freezing compartment  13  through rotation thereof. For this, all the refrigerating compartment door  21  and the freezing compartment door  22  may be rotatably connected to the cabinet  10  through a hinge device  23 . Also, the refrigerating compartment door  21  may be a French type door in which a pair of doors disposed on both left and right sides independently rotates. 
     A filler  26  may be provided on an end of the refrigerating compartment door  21  at sides of the pair of refrigerating compartment doors  21 . The filler  26  may be configured to shield a space (or gap) between the refrigerating compartment doors  21  disposed on both left and right sides of the refrigerating compartment door  21  when the refrigerating compartment door  21  is closed. 
     For this, the filler  26  may be provided at one end of the refrigerating compartment door  21 , that is, at one end that is far from the end at which the hinge device  23  is mounted. In addition, the filler  26  may be rotatably mounted. Also, in a state in which the refrigerating compartment door  21  is opened, the filler  26  may be in a folded state, and in a state in which the refrigerating compartment door  21  is closed, the filler  26  may be in a closed state to shield a gap between the pair of refrigerating compartment doors  21 . For this, a filler guide  103  may be disposed at a front end of a top surface of the refrigerating compartment  12 . The filler guide  103  may be disposed inside a center of the refrigerating compartment  12 , and when the refrigerating compartment door  21  is closed, the filler  26  may be inserted to guide the rotation of the filler  26 . 
     A dispenser  24  and an ice maker  252  may be provided in the refrigerating compartment door disposed at one side of the pair of refrigerating compartment doors  21 . 
     The dispenser  24  may be disposed on a front surface of the refrigerating compartment door  21 , and a user may manipulate the dispenser  24  from the outside to dispense water or ice. Also, an ice making chamber  25  is provided above the dispenser  24 . 
     The ice making chamber  25  may be provided in a rear surface of the refrigerating compartment door  21  to define an insulating space in which ice is made and stored, and the ice maker  252  may be mounted in the ice making chamber  25 . In addition, the ice making chamber  25  may be configured to be opened and closed by the ice making chamber door  251 . 
     The ice making chamber  25  may communicate with the dispenser  24 , and thus, ice in the ice making chamber  25  may be dispensed by a manipulation of the dispenser  24 . 
     Cold air generated in (or by) the freezing compartment evaporator  131  may be supplied into the ice making chamber  25  to perform an ice making operation in the ice maker  252 . For this, an ice making passage  14  for supplying the cold air into the ice making chamber  25  may be provided in the cabinet  10 . The ice making passage  14  may be provided between the outer case  101  and the inner case  102  and may be disposed by being buried in the insulating material. The ice making passage  14  may be disposed on one side surface of the refrigerating compartment door  21  at one side of the left and right side surfaces. 
     The ice making passage  14  may include a supply duct  141  for supplying the cold air into the ice making chamber  25  and a return duct  142  in which the heat-exchanged air in the ice making chamber  25  is disposed. 
     The supply duct  141  may extend from a rear end of the freezing compartment  13 , in which the freezing compartment evaporator  131  is disposed, to one side surface of the refrigerating compartment  12 . That is, in the state in which the refrigerating compartment door  21  is closed, the space, in which the freezing compartment evaporator  131  is disposed, and the inside of the ice making chamber  25  may communicate with each other to guide the cold air of the freezing compartment evaporator  131  to the ice making chamber  25 . 
     The return duct  142  may extend from one side surface of the refrigerating compartment  12 , which is in contact with the refrigerating compartment door  21  in the closed state, to a lower portion of the freezing compartment  13 . That is, in the state in which the refrigerating compartment door  21  is closed, the freezing compartment  13  and the inside of the ice making chamber  25  may communicate with each other to guide the air, which is heat-exchanged for the ice making in the ice making chamber  25 , to the freezing compartment  13 . 
     A supply opening  141   a  and a return opening  142   a , which are disposed at ends of the supply duct  141  and the return duct  142  constituting the ice making passage  14 , respectively, may be opened at the side surface of the refrigerator compartment  12  adjacent to the refrigerator compartment door  21 . The supply opening  141   a  and the return opening  142   a  may communicate with a passage connected to the ice making chamber  25  at the side surface of the refrigerating compartment door  21  when the refrigerating compartment door  21  is closed. 
     The other end of the supply duct  141  may be opened at one wall surface of the inner case  102  to communicate with the space, in which the freezing compartment evaporator  131  is disposed, to define a duct inlet  141   b . The other end of the return duct  142  may be opened at one wall surface of the inner case  102  adjacent to a suction hole, through which the cold air is suctioned to a lower portion of the freezing compartment  13  (i.e., the freezing compartment evaporator  131 ). 
     Thus, in the state in which the refrigerating compartment door  21  is closed, the space, in which the ice making chamber  25 , the freezing compartment  13 , and the space, in which the freezing compartment evaporator  131  is disposed, communicate with each other, may be defined. 
     To provide such a structure, at least a portion of the ice making passage  14  (i.e., the supply duct  141  and the return duct  142 ) may be disposed on the side wall surface of the refrigerating compartment  12 . Thus, the cold air flowing through the ice making passage  14  may penetrate into the refrigerating compartment  12 . 
     The cold air transferred to the inside of the refrigerating compartment  12  by the ice making passage  14  may not be large enough to cause supercooling or storage performance of the refrigerating compartment  12 . However, when the defrosting operation for removing frost generated on the refrigerating compartment evaporator  121  is performed, the cold air transferred from the ice making passage  14  may affect the defrosting operation (S 200 ). Particularly, in the case of natural defrosting, in which high-temperature air of the refrigerating compartment  12  is forcibly introduced into (or to) the refrigerating compartment evaporator  121  to remove the frost of the refrigerating compartment evaporator  121 , efficiency of the defrosting operation (S 200 ) may deteriorate due to the penetration of the cold air. Thus, during the defrosting operation, the filler heater  265 , disposed on the filler  26 , may operate to more efficiently perform the defrosting operation. 
     A structure of the filler  26  will be described in more detail with reference to the drawings. 
       FIG. 4  is a perspective view illustrating the refrigerating compartment door of the refrigerator.  FIG. 5  is a cross-sectional view taken along line V-V′ of  FIG. 1 . 
     The filler  26  may be provided at the refrigerating compartment door  21 , in which the ice making chamber  25  is defined, of the pair of refrigerating compartment doors  21  disposed side by side on the left and right sides. The filler  26  may be provided at one end opposite to one end, on which the hinge device  23  is mounted, of both left and right ends. That is, the filler  26  may be provided at one end of the pair of refrigerating compartment doors  21  adjacent to each other and be configured to shield a space (or shield a gap) between the pair of refrigerating compartment doors  21  when the pair of refrigerating compartment doors  21  are closed. 
     The filler  26  may extend long in a vertical direction along one end of the refrigerating compartment door  21 . In addition, the filler  26  may be rotatably connected to the refrigerating compartment door  21  by a connection member  262 . The connection member  262  may be vertically provided in plurality. In addition, the connection member  262  may be provided with an elastic member so that, when the refrigerating compartment door  21  is opened, the filler  26  is folded into the refrigerating compartment door  21  as illustrated in  FIG. 4 . 
     A guide protrusion  261  may be disposed on an upper end of the filler  26 . The guide protrusion  261  may be inserted into an opening groove of the filler guide  103  when the refrigerator compartment door  21  is closed. A surface on which the guide protrusion  261  and the filler guide  103  are in contact with each other may be rounded, and the filler  26  may be rotatably unfolded while the refrigerator compartment door  21  is closed. 
     When all of the pair of refrigerating compartment doors  21  are closed, the filler  26  may be unfolded as illustrated in  FIG. 5 , and each of gaskets  27  provided on the pair of refrigerating compartment doors  21  may be in close contact with a front surface of the filler  26 . Thus, the filler  26  may prevent the cold air of the refrigerating compartment  12  from leaking through between the pair of refrigerating compartment doors  21  when the pair of refrigerating compartment doors  21  are closed. 
     The filler  26  may define an outer appearance and may include a filler case  263  filled with the insulating material therein, and a filler cover  264  defining a front surface of the filler case  263 . The filler cover  264  may be made of a steel material and may be in contact with the gasket  27 . 
     A filler heater  265  may be provided inside the filler case  263 . The filler heater  265  may heat the filler cover  264  and may prevent dew condensation from occurring on the filler cover  264  and the gasket  27  that is in contact with the filler cover  264 . 
     Although the dew condensation occurs between the pair of refrigerating compartment doors  21 , which are relatively poorly insulated due to a temperature difference between the cold air inside the refrigerating compartment  12  and external air, the front surface of the filler  26 , or one side of the gasket  27  that is contact with the filler  26 , the filler  26 , in particularly, the front surface of the filler  26  may be heated based on operation of the filler heater  265  to prevent the dew condensation from occurring. 
     The filler heater  265  may be configured as a heater made of a wire material and may be vertically disposed inside the filler  26 . In addition, the filler heater  265  may be disposed in close contact with the front surface of the filler  26 . In addition, the filler heater  265  may be disposed along a circumference of the filler  26  or be bent several times to define an overall length that is longer than a length of the filler  26  and may increase in contact area with the front surface of the filler  26 . 
     An on/off operation of the filler heater  265  may be controlled by a controller  30 . The filler heater  265  may detect a temperature of an external space, in which the refrigerator  1  is installed, which is detected by a temperature sensor  33  outside the refrigerator, to determine an operation period thereof. For example, when the temperature detected by the temperature sensor  33  outside the refrigerator increases, and a temperature difference with the refrigerating compartment  12  increases, the operation period of the filler heater  265  may be shortened to effectively prevent the dew condensation from occurring. In addition, since the internal temperature of the refrigerating compartment  12  increases when an operation time of the filler heater  265  is prolonged, the operation of the filler heater  265  may be controlled by the controller  30  at an optimal cycle. 
     While the refrigerating compartment  12  operates normally, the controller  30  may set and control the operation cycle according to the detected temperature of the external air, which is detected by the temperature sensor  33  outside the refrigerator, but in even the case, in which the natural defrosting operation of the refrigerating compartment evaporator  121  is performed, the filler heater  265  may be turned on to more efficiently perform the natural defrosting operation of the refrigerating compartment evaporator  121 . 
     The operation of the refrigerator  1  according to an embodiment will be described in more detail with reference to the drawings. 
       FIG. 6  is a block diagram illustrating a flow of a control signal in the refrigerator according to an embodiment.  FIG. 7  is a flowchart sequentially illustrating processes of performing the defrosting operation of the refrigerator according to an embodiment. 
     The refrigerator  1  may operate so that the refrigerating compartment  12  and the freezing compartment  13  are maintained to set temperatures in the normal operation state. That is, the controller  30  may control operations of the compressor  34 , the refrigerating compartment fan  122 , and the freezing compartment fan  132  according to the temperatures of the refrigerating compartment  12  and the freezing compartment  13 , which are detected by the temperature sensor  32  inside the refrigerator  1  so that the refrigerating compartment  12  and the freezing compartment  13  are maintained to a set temperature or temperature range. 
     The controller  30  may allow the filler heater  265  to operate in a set cycle according to the temperature detected by the temperature sensor  33  (outside the refrigerator  1 ), thereby preventing the dew condensation from occurring on an adjacent portion between the pair of refrigerating compartment doors  21 . [S 100 ] 
     While the normal operation of the refrigerator  1  is performed, moisture of food stored in the refrigerating compartment  12  or moisture introduced when the refrigerating compartment door  21  is opened or closed may be deposited on the refrigerating compartment evaporator  121 . In addition, when frost generated on the refrigerating compartment evaporator  121  is grown, cooling performance of the refrigerating compartment  12  may deteriorate. As a result, a defrosting operation (S 200 ) of removing the frost generated on the refrigerating compartment evaporator  121  may be performed. 
     According to this embodiment, in the defrosting operation (S 200 ), the refrigerating compartment evaporator  121  may not be directly heated by a heater attached to the refrigerating compartment evaporator  121 , but high-temperature air of the refrigerating compartment  12  may be supplied to the refrigerating compartment evaporator  121  to remove the frost. Thus, the defrosting operation may be referred to as a natural defrosting operation (S 200 ) so as to be distinguished from a defrosting operation in which the refrigerating compartment evaporator  121  is directly heated using a heater. 
     The defrosting operation (S 200 ) may be performed at a set period to prevent the frost from being grown on the refrigerating compartment evaporator  121 . For example, in the defrosting operation S 200 , the controller  30  may determine an appropriate time point by accumulating the operation time of the compressor  34  to input (or provide) a defrost signal. The defrosting operation (S 200 ) may be performed every set period by the controller  30  and also may be set to a period based on the number of times of opening and closing of the refrigerator compartment door  21 , the temperature detected by the temperature sensor  32  inside the refrigerator and/or the defrosting temperature sensor  31  as well as the operating time of the compressor  34 . [S 210 ] 
     When a starting signal of the defrosting operation (S 200 ) is input (or provided) from the controller  30 , the controller  30  may stop the operation of the compressor  34  to stop the supply of the refrigerant to the refrigerating compartment evaporator  121 . When the supply of the cold air to the refrigerating compartment evaporator  121  is stopped, the temperature of the refrigerating compartment evaporator  121  is no longer lowered. Of course, the refrigerant discharged from the compressor  34  may be switched to be supplied to the freezing compartment evaporator  131 . In this case, the cold air may be supplied through the ice making passage  14  and also may allow ice to be made in the ice maker  252 . 
     Also, when the compressor  34  is stopped, the controller  30  may turn on the refrigerating compartment fan  122 . When the refrigerating compartment fan  122  is driven, air inside the refrigerating compartment  12  may be continuously introduced into (or to) the refrigerating compartment evaporator  121 . The temperature of the refrigerating compartment  12  may be approximately 0° C. or more, which is higher than that of the refrigerating compartment evaporator  121 . Therefore, when supplied to the refrigerating compartment evaporator  121 , the temperature of the refrigerating compartment evaporator  121  may increase. 
     That is, as the refrigerating compartment fan  122  is driven, the high-temperature air inside the refrigerating compartment  12  may be introduced into (or to) the refrigerating compartment evaporator  121  and then be discharged to the refrigerating compartment  12  by passing (or passing through) the refrigerating compartment evaporator  121 . In addition, the temperature of the refrigerating compartment  12  may be usually about 3° C. to about 5° C. When the high-temperature air inside the refrigerating compartment  12  is supplied to the refrigerating compartment evaporator  121 , the temperature of the refrigerating compartment evaporator  121  may increase, and thus, the frost generated on the refrigerating compartment evaporator  121  may melt and may be removed. [S 220 ] 
     The controller  30  may turn on the filler heater  265  according to the input of the signal of the defrosting operation (S 200 ). The filler heater  265  may operate while being turned on and off at a set period during the normal operation, but may be controlled to maintain the ON state during the defrosting operation (S 200 ) by the controller  30 . 
     When the filler heater  265  is turned on, the front surface of the filler  26  may be heated by the filler heater  265 . At the same time, heat of the filler  26  may penetrate into the inside of the refrigerating compartment  12 , and the refrigerating compartment  12  may be heated by the heat penetrated into the refrigerating compartment  12 . The heated air inside the refrigerating compartment  12  may be continuously supplied to the refrigerating compartment evaporator  121  by the operation of the refrigerating compartment fan  122 . 
     That is, if the filler heater  265  is maintained in the ON state during the defrosting operation (S 200 ), the frost of the refrigerating compartment evaporator  121  may be more effectively removed, and a time taken to reach the set temperature for completing the defrosting may be shortened. 
     During the defrosting operation (S 200 ), when the supply of the refrigerant to the refrigerating compartment evaporator  121  is cut off, the filler heater  265  may be turned on to provide additional heat to the inside of the refrigerating compartment  12 , and at the same time, the refrigerating compartment fan  122  may allow the high-temperature air of the refrigerating compartment  12  to continuously pass through the refrigerating compartment fan  122  so that the temperature of the refrigerating compartment evaporator  121  increases to remove the frost generated on the refrigerating compartment evaporator  121 . The filler heater  265  may be turned on simultaneously with the operation of turning off the compressor and turning on the refrigerating compartment fan. [S 230 ] 
     The temperature of the refrigerating compartment evaporator  121  may increase based on the continuous operation of the filler heater  265  and the refrigerating compartment fan  122 . The temperature of the refrigerating compartment evaporator  121  may be detected by the defrosting temperature sensor  31 . 
     When the defrosting operation (S 200 ) starts, the temperature detected by the defrosting temperature sensor  31  may be maintained in the deposited state at a temperature below zero, but the temperature detected by the defrosting temperature sensor  31  may gradually increase by the driving of the refrigerating compartment fan  122  and the filler heater  265 . In addition, the frost that has been deposited on the refrigerating compartment evaporator  121  may be removed by beginning to be melted when the temperature detected by the defrosting temperature sensor  31  reaches about 0° C. or more. 
     The controller  30  may determine completion of the defrosting operation S 200  through the temperature detected by the defrosting temperature sensor  31 . In the controller  30 , when the temperature detected by the defrosting temperature sensor  31  is lower than about 3° C. to about 5° C. corresponding to the temperature of the refrigerating compartment  12 , the filler heater  265  and the refrigerating compartment fan  122  may be continuously maintained in the ON state. 
     When the temperature detected by the defrosting temperature sensor  31  reaches a set temperature, for example, about 3° C. to about 5° C., the controller  30  may determine that the frost deposited on the refrigerating compartment evaporator  121  is sufficiently removed so that the temperature of the refrigerating compartment evaporator  121  increases and thus determine that the defrosting operation (S 200 ) is completed. [S 240 ] 
     When the temperature detected by the defrosting temperature sensor  31  reaches the set temperature, the controller  30  may turn off the filler heater  265  to complete the defrosting operation (S 200 ) and finish the defrosting operation (S 200 ). Also, when the filler heater  265  is stopped, the refrigerating compartment fan  122  may also be stopped. 
     When the defrosting operation (S 200 ) is completed, the operation may return to the normal operation to cool the refrigerating compartment  12 . That is, driving of the compressor  34  may start to supply the cold air to the refrigerating compartment evaporator  121 , and driving of the refrigerating compartment fan  122  may also start to supply the cold air of the refrigerating compartment evaporator  121  into the refrigerating compartment  12 . 
     The operation of the compressor  34  and the refrigerating compartment fan  122  may be controlled according to the temperature detected by the temperature sensor  32  inside the refrigerator  1  so that the refrigerating compartment  12  is maintained to the set temperature. 
     In the defrosting operation (S 200 ), when the temperature of the refrigerating compartment  12  increases up to an excessively high temperature at once, a storage state of the food stored in the refrigerating compartment  12  may not be maintained in an optimal state, and thus, the defrosting operation (S 200 ′) may be divided into a plurality of processes. 
     Another embodiment in which the defrosting operation (S 200 ′) is divided into the plurality of processes will be described. In another embodiment, the same reference numerals are used for the same components as those of the foregoing embodiment, and a detailed description thereof may be omitted. 
       FIG. 8  is a flowchart sequentially illustrating processes of performing a defrosting operation of a refrigerator according to another embodiment. 
     As illustrated in the drawing, the refrigerator  1  may operate normally so that each of the refrigerating compartment  12  and the freezing compartment  13  are maintained at a set temperature or a temperature range. For this, the controller  30  may control operations of the compressor  34 , the refrigerating compartment fan  122 , and the freezing compartment fan  132  according to a temperature detected by a temperature sensor inside the refrigerator  1 . In addition, the controller  30  may control an operation of the filler heater  265  according to a temperature detected by a temperature sensor  33  outside the refrigerator  1  to prevent dew condensation from occurring. [S 100 ] 
     The controller  30  may perform a defrosting operation (S 200 ′) at an appropriate time point to prevent frost from being generated on the refrigerator compartment evaporator  121  and thereby to deteriorate cooling efficiency during the normal operation of the refrigerator  1 . The defrosting operation (S 200 ′) may include a first defrosting operation process  260 , a rapid cooling operation process  270 , and a second defrosting operation process  280 , which are initially performed. 
     The controller  30  may input (or provide) a defrost signal by accumulating the operating time point of the compressor  34  to determine an appropriate time point for starting the defrosting operation (S 200 ′). The defrosting operation (S 200 ′) may be performed every set period by the controller  30  and also may be set based on the number of times of opening and closing of the refrigerator compartment door  21  or the temperature detected by the temperature sensor  32  inside the refrigerator or the defrosting temperature sensor  31  as well as the operating time of the compressor  34 . [S 261 ] 
     When starting the defrosting operation (i.e., a starting signal of the first defrosting operation process  260  is input from the controller  30 ), the controller  30  may stop the operation of the compressor  34  to stop the supply of the refrigerant to the refrigerating compartment evaporator  121 . When the supply of the cold air to the refrigerating compartment evaporator  121  is stopped, the temperature of the refrigerating compartment evaporator  121  is no longer lowered. Of course, the refrigerant discharged from the compressor  34  may be switched to be supplied to the freezing compartment evaporator  131 . In this case, the cold air may be supplied through the ice making passage  14  and also may allow ice to be made in the ice maker  252 . 
     The controller  30  may turn on the refrigerating compartment fan  122 . When the refrigerating compartment fan  122  is driven, air inside the refrigerating compartment  12  may be continuously introduced to (or into) the refrigerating compartment evaporator  121 . Here, the temperature of the refrigerating compartment  12  may be about 0° C. or more, which is higher than that of the refrigerating compartment evaporator  121 . Therefore, when supplied to the refrigerating compartment evaporator  121 , the temperature of the refrigerating compartment evaporator  121  may increase. When the temperature of the refrigerating compartment evaporator  121  increases, the frost deposited on the refrigerating compartment evaporator  121  may melt and may be removed. 
     The controller  30  may turn on the filler heater  265 . The filler heater  265  may operate while being turned on and off at a set period during the normal operation (S 100 ), but may be controlled to maintain the ON state during the first defrosting operation process  260  by the controller  30 . 
     When the filler heater  265  is turned on, the front surface of the filler  26  may be heated by the filler heater  265 . Also, at the same time, heat of the filler  26  may penetrate into the inside of the refrigerating compartment  12 , and the refrigerating compartment  12  may be heated by the heat penetrated into the refrigerating compartment  12 . In addition, the heated air inside the refrigerating compartment  12  may be continuously supplied to the refrigerating compartment evaporator  121  by the operation of the refrigerating compartment fan  122 . 
     If the filler heater  265  is maintained in the ON state during the first defrosting operation process  260 , the frost of the refrigerating compartment evaporator  121  may be more effectively removed, and a time taken to reach the set temperature for completing the first defrosting operation process  260  may be shortened. 
     During the first defrosting operation process  260 , when the supply of the refrigerant to the refrigerating compartment evaporator  121  is cut off, the filler heater  265  may be turned on to provide additional heat to the inside of the refrigerating compartment  12 , and at the same time, the refrigerating compartment fan  122  may allow the high-temperature air of the refrigerating compartment  12  to continuously pass through the refrigerating compartment fan  122  so that the temperature of the refrigerating compartment evaporator  121  increases to remove the frost generated on the refrigerating compartment evaporator  121 . The filler heater may be turned on simultaneously with the operation of turning off the compressor and turning on the refrigerating compartment fan. [S 263 ] 
     The temperature of the refrigerating compartment evaporator  121  may increase based on the continuous operation of the filler heater  265  and the refrigerating compartment fan  122 . The temperature of the refrigerating compartment evaporator  121  may be detected by the defrosting temperature sensor  31 . 
     When the first defrosting operation process  260  starts, the temperature detected by the defrosting temperature sensor  31  may be maintained in the deposited state at a temperature below zero, but the temperature detected by the defrosting temperature sensor  31  may gradually increase by the driving of the refrigerating compartment fan  122  and the filler heater  265 . In addition, the frost that has been deposited on the refrigerating compartment evaporator  121  may be removed by beginning to be melted when the temperature detected by the defrosting temperature sensor  31  reaches about 0° C. or more. 
     The controller  30  may determine the completion of the first defrosting operation process  260  through the temperature detected by the defrosting temperature sensor  31 . In the controller  30 , when the temperature detected by the defrosting temperature sensor  31  is lower than about 3° C., the filler heater  265  and the refrigerating compartment fan  122  may be continuously maintained in the ON state. 
     When the temperature detected by the defrosting temperature sensor  31  reaches a set temperature, for example, approximately 3° C., the controller  30  may determine that the first defrosting operation process  260  is sufficiently performed and may determine that the first defrosting operation process  260  is completed. 
     When the temperature detected by the defrosting temperature sensor  31  reaches a first set temperature, the controller  30  may turn off the filler heater  265  to complete the first defrosting operation process  260 . The refrigerating compartment fan  122  may also be stopped. [S 265 ] 
     If the internal temperature of the refrigerating compartment  12  continuously increases after the first defrosting operation process  260  is completed, the food stored in the refrigerating compartment  12  may be deteriorated or damaged. Thus, when the first defrosting operation process  260  is completed, the controller  30  may perform the rapid cooling operation process  270  for rapidly cooling the refrigerating compartment  12 . 
     For the rapid cooling operation process  270 , the controller may turn off the filler heater  265  and turn on the compressor  34  and the refrigerating compartment fan  122  to supply the cold air generated in the refrigerating compartment evaporator  121  to the refrigerating compartment  12 . 
     The rapid cooling operation process  270  may be performed for a short time for efficiency of the subsequent second defrosting operation process  280  and may operate at a temperature that is significantly lower than a target temperature during the normal operation (S 100 ). For example, the rapid cooling operation process  270  may be performed until the temperature of the refrigerating compartment evaporator  121  detected by the defrosting temperature sensor  31  is about −20° C. or less. The compressor  34  may operate at a maximum output to rapidly cool the refrigerating compartment  12 . 
     The rapid cooling operation process  270  may be ended when the defrosting temperature sensor  31  or the temperature sensor  32  inside the refrigerator  1  reaches the target temperature. Of course, if necessary, the rapid cooling operation process  270  may be performed for a set time regardless of the temperature. [S 270 ] 
     When the rapid cooling operation process  270  is ended, the controller  30  may perform again a second defrosting operation process  280  for additionally removing the frost remaining on the refrigerating compartment evaporator  121 . 
     When the restarting of the defrosting operation (S 200 ′) (i.e., a starting signal of the second defrosting operation process  280  is input from the controller  30 ), the controller  30  may stop the operation of the compressor  34  to stop the supply of the refrigerant to the refrigerating compartment evaporator  121 . When the supply of the cold air to the refrigerating compartment evaporator  121  is stopped, the temperature of the refrigerating compartment evaporator  121  is no longer lowered. Of course, the refrigerant discharged from the compressor  34  may be switched to be supplied to the freezing compartment evaporator  131 . 
     The controller  30  may turn on the refrigerating compartment fan  122 . When the refrigerating compartment fan  122  is driven, air inside the refrigerating compartment  12  may be continuously introduced into (or to) the refrigerating compartment evaporator  121 . Here, the temperature of the refrigerating compartment  12  may be about 0° C. or more, which is higher than that of the refrigerating compartment evaporator  121 . Therefore, when supplied to the refrigerating compartment evaporator  121 , the temperature of the refrigerating compartment evaporator  121  may increase. When the temperature of the refrigerating compartment evaporator  121  increases, the frost deposited on the refrigerating compartment evaporator  121  may melt and may be removed. [S 282 ] 
     The controller  30  may turn on the filler heater  265 . The filler heater  265  may operate while being turned on and off at a set period during the normal operation (S 100 ), but may be controlled to maintain the ON state during the second defrosting operation process  280  by the controller  30 . 
     When the filler heater  265  is turned on, the front surface of the filler  26  may be heated by the filler heater  265 . At the same time, heat of the filler  26  may penetrate into the inside of the refrigerating compartment  12 , and the refrigerating compartment  12  may be heated by the heat penetrated into the refrigerating compartment  12 . In addition, the heated air inside the refrigerating compartment  12  may be continuously supplied to the refrigerating compartment evaporator  121  by the operation of the refrigerating compartment fan  122 . 
     That is, if the filler heater  265  is maintained in the ON state during the second defrosting operation process  280 , the frost of the refrigerating compartment evaporator  121  may be more effectively removed, and a time taken to reach the set temperature for completing the second defrosting operation process  280  may be shortened. 
     During the second defrosting operation process  280 , when the supply of the refrigerant to the refrigerating compartment evaporator  121  is cut off, the filler heater  265  may be turned on to provide additional heat to the inside of the refrigerating compartment  12 , and at the same time, the refrigerating compartment fan  122  may allow the high-temperature air of the refrigerating compartment  12  to continuously pass through the refrigerating compartment fan  122  so that the temperature of the refrigerating compartment evaporator  121  increases to remove the frost generated on the refrigerating compartment evaporator  121 . The filler heater  265  may be turned on simultaneously with the operation of turning off the compressor and turning on the refrigerating compartment fan. [S 283 ] 
     The temperature of the refrigerating compartment evaporator  121  may increase based on the continuous operation of the filler heater  265  and the refrigerating compartment fan  122 . The temperature of the refrigerating compartment evaporator  121  may be detected by the defrosting temperature sensor  31 . 
     When the second defrosting operation process  280  starts, the temperature detected by the defrosting temperature sensor  31  may be in a state in which the frost is deposited at a temperature below zero, but the temperature detected by the defrosting temperature sensor  31  may gradually increase by the driving of the refrigerating compartment fan  122  and the filler heater  265 . In addition, the frost that has been deposited on the refrigerating compartment evaporator  121  may be removed by beginning to be melted when the temperature detected by the defrosting temperature sensor  31  reaches about 0° C. or more. 
     The controller  30  may determine the completion of the second defrosting operation process  280  through the temperature detected by the defrosting temperature sensor  31 . In the controller  30 , when the temperature detected by the defrosting temperature sensor  31  is lower than a second set temperature, the filler heater  265  and the refrigerating compartment fan  122  may be continuously maintained in the ON state. 
     When the temperature detected by the defrosting temperature sensor  31  reaches the second set temperature, for example, approximately 5° C., the controller  30  may determine that the second defrosting operation process  280  is sufficiently performed and may determine that the second defrosting operation process  280  is completed. 
     The second set temperature may be a temperature that is higher than the first set temperature and a temperature at which the removal of the frost on the refrigerating compartment evaporator  121  is secured, and may be in a range in which the temperature inside the refrigerating compartment  12  does not excessively increase. 
     Since the second set temperature of the second defrosting operation process  280  is higher than the first set temperature, the second defrosting operation process  280  may be performed for a time that is longer than that of the first defrosting operation process  260 . [S 284 ] 
     When the temperature detected by the defrosting temperature sensor  31  reaches a first set temperature, the controller  30  may turn off the filler heater  265  to complete the first defrosting operation process  260 , i.e., the defrosting operation (S 200 ′). Here, the refrigerating compartment fan  122  may also be stopped. [S 285 ] 
     When the defrosting operation (S 200 ′) is completed, the operation may return to the normal operation (S 100 ) to cool the refrigerating compartment  12 . That is, the driving of the compressor  34  may start to supply the cold air to the refrigerating compartment evaporator  121 , and the driving of the refrigerating compartment fan  122  may also start to supply the cold air of the refrigerating compartment evaporator  121  into the refrigerating compartment  12 . 
     The operation of the compressor  34  and the refrigerating compartment fan  122  may be controlled according to the temperature detected by the temperature sensor  32  inside the refrigerator  1  so that the refrigerating compartment  12  is maintained to the set temperature. 
     A change in state of the refrigerator during the defrosting operation of the refrigerator  1  according to the foregoing embodiment will be described with reference to the drawings. 
       FIG. 9  is a graph illustrating a defrosting operation state when the filler heater does not operate in the refrigerator according to an embodiment.  FIG. 10  is a graph illustrating a defrosting operation state when the filler heater operates in the refrigerator according to an embodiment. 
     As illustrated in the drawings, when the filler heater  265  is not driven while the defrosting operation is being performed, as illustrated in  FIG. 9 , the defrosting operation may be performed for about 6 hours and then be ended so that the temperature detected by the defrosting temperature sensor  31  reaches the set temperature (about 5° C.) at which the frost deposited on the refrigerating compartment evaporator  121  is completely removed. 
     However, as in this embodiment, when the defrosting operation (S 200 ′) is performed, if the filler heater  265  is turned on, an additional amount of heat may be provided to the refrigerating compartment  12 . As illustrated in  FIG. 10 , the defrosting operations  200  and  200 ′ may be performed for about 4 hours and then ended so that the temperature detected by the defrosting temperature sensor  31  reaches the set temperature (about 5° C.) at which the frost deposited on the refrigerating compartment evaporator  121  is completely removed. 
     In detail, in the defrosting operation (S 200 ′), the filler heater  265  may be turned on during the first defrosting operation process, and a temperature of the filler heater  265  and the temperature detected by the defrosting temperature sensor  31  may continuously increase. The first defrosting operation process  260  may be performed until the temperature detected by the defrosting temperature sensor  31  reaches a first set temperature T 1  (approximately 3° C.), and the temperature of the filler heater may continuously increase to reach a first filter temperature T 3  (about 8° C.). 
     After the first defrosting operation process  260  is ended, the rapid cooling operation process (S 270 ) is performed so that the compressor  34  and the refrigerating compartment fan  122  operate, and the filler heater  265  is turned off. Thus, the temperatures of the defrosting temperature sensor  31  and the filler heater  265  decrease. 
     When the rapid cooling operation process S 270  is ended, the second defrosting operation process  280  may be performed. The filler heater  265  may be turned on during the second defrosting operation process  280 , and the temperature of the filler heater  265  and the temperature detected by the defrosting temperature sensor  31  may continuously increase. The second defrosting operation process  280  may be performed until the temperature detected by the defrosting temperature sensor  31  reaches a first set temperature T 2  (approximately 5° C.), and the temperature of the filler heater may continuously increase to reach a second filter temperature T 4  (about 12° C.). 
     The second set temperature T 2  may be relatively higher than the first set temperature T 1 . Thus, the second defrosting operation process  280  may be performed longer than the first defrosting operation process S 260 . Also, until the second defrosting operation step  280  is completed, the filler heater  265  may be continuously turned on to continuously provide heat to the inside of the refrigerating compartment  12 . 
     When the second defrosting operation step  280  is completed, the controller  30  may turn off the filler heater  265 , and the compressor  34  and the refrigerator compartment fan  122  may be driven to cool the refrigerator compartment  12  again, and thus, the process may return again to the normal operation. 
     In the drawings, although the defrosting operations S 200  and S 200 ′ are performed at one time, the defrosting operations S 200  and S 200 ′ may be repeatedly performed at a set period by the controller  30 . 
     The refrigerator and the method for controlling the refrigerator according to the embodiment may have the following effects. 
     According to the embodiment, when the defrosting operation is performed to remove the frost formed on the refrigerating compartment evaporator, the filler heater may be turned on to provide the heat into the refrigerating compartment. Therefore, the air may be supplied into the refrigerating compartment, which is heated by the refrigerating compartment evaporator, due to the driving of the refrigerating compartment fan to improve the natural defrosting efficiency inside the refrigerating compartment. 
     That is, when compared to the manner according to the related art, in which the refrigerating compartment evaporator is directly heated by the heater through the defrosting operation, the power consumption may be significantly reduced. In addition, even in the case of the natural defrosting, the filler heater may be used to additionally apply the heat into the refrigerating compartment, and thus, the defrosting operation time may be reduced to reduce the power consumption and maintain the optimal state of the food in the refrigerating compartment. 
     Particularly, the filler heater may be disposed to prevent the dew condensation from occurring on the pair of refrigerating compartment doors and may be used for performing the defrosting operation as well as preventing the dew condensation from occurring on the refrigerating compartment doors to significantly improve the efficiency of the defrosting operation without adding the separate heater and changing the configuration of the refrigerator. 
     When the ice making chamber, in which the ice is made, is provided in the refrigerating compartment door, and the ice making passage for supplying the cold air of the freezing compartment evaporator to the ice making chamber is provided on the side surface of the cabinet, a portion of the ice making passage may be disposed on the wall surface of the refrigerating compartment to transfer the cold air to the inside of the refrigerator. 
     As described above, the cold air transferred to the inside of the refrigerator may not have a limitation in the general normal operation, but the defrosting time may become longer in the natural defrosting for forcibly supplying the air of the refrigerating compartment to heat the refrigerating compartment evaporator. The filer heater may be driven to supply a greater amount of heat than that of the cold air transferred through the ice making passage, and thus, even in the natural defrosting, the inside of the refrigerating compartment may be effectively heated to improve the efficiency of the defrosting operation. 
     That is, in this embodiment, when the defrosting operation is performed, the filler heater may be driven to prevent the defrosting operation efficiency from being deteriorated in even the structure, in which the ice maker is disposed in the refrigerating compartment door, and the ice making passage is disposed in the region of the refrigerating compartment, thereby effectively performing the defrosting operation. 
     The defrosting operation may be performed by dividing the first defrosting operation process, the quick cooling operation process, and the second defrosting operation process. In the first defrosting operation process and the second defrosting operation process, the heat may be applied to the inside of the refrigerating compartment by the filler heater. Particularly, in the second defrosting operation process in which the target set temperature is high, the target set temperature may be quickly reached by the filler heater, and also, the time taken to perform the second defrosting operation process, in which the target set temperature is relatively high, may be minimized to prevent the damage of the food while maintaining the defrosting performance. 
     Embodiments also provide a refrigerator in which defrosting operation efficiency is improved to reduce power consumption, and a method for controlling the refrigerator. 
     Embodiments also provide a refrigerator in which a filler heater operates when a defrosting operation is performed to additionally provide heat during the defrosting operation, and a method for controlling the refrigerator. 
     Embodiments also provide a refrigerator in which a time taken to perform a defrosting operation is reduced in the refrigerator in which a cold air passage is provided toward an ice maker in a region of a refrigerating compartment, and a method for controlling the refrigerator. 
     In one embodiment, a refrigerator includes: a cabinet in which a refrigerating compartment cooled by cold air, which is supplied by a refrigerating compartment evaporator and a refrigerating compartment fan, and a freezing compartment cooled by cold air, which is supplied by a freezing compartment evaporator and a freezing compartment fan, are defined; a pair of doors configured to be opened and closed by rotation of the refrigerating compartment; a filler provided on one of the pair of doors to shield a gap between the pair of doors in a state in which the pair of doors are closed; a filler heater provided inside the filler; and a controller configured to control operations of the refrigerating compartment fan, the freezing compartment fan, the filler heater, and a compressor, wherein, when the refrigerating compartment evaporator performs a defrosting operation, the controller turns on the refrigerating compartment fan and the filler heater in state in that the compressor turns off so that heated air inside the refrigerating compartment is circulated to pass through the refrigerating compartment evaporator. 
     The filler heater may be turned on or off according to a temperature of external air, which is detected by a temperature sensor outside the refrigerator, and be maintained in the state of turned on during the defrosting operation. 
     The filler heater may be turned on when the defrosting operation starts and be turned off when the defrosting operation is ended. 
     The filler heater may be maintained in the state of being turned on until a temperature detected by a defrosting temperature sensor configured to detect a temperature of the evaporator reaches a set temperature. 
     When the defrosting operation is performed, the controller may be configured to: turn off the filter heater when the temperature detected by the defrosting temperature sensor reaches a first set temperature to quickly cool the refrigerating compartment; and turn on again the filler heater after the quick cooling operation is completed, to turn off the filler heater when the temperature detected by the defrosting temperature sensor reaches a second set temperature. 
     The second set temperature may be set to be higher than the first set temperature. 
     The first set temperature may be set to a temperature of about 3° C., the second set temperature may be set to a temperature of about 5° C. 
     When the quick cooling operation is performed, the compressor and the refrigerating compartment fan may be turned on. 
     When the quick cooling operation is performed, the compressor may operate for a set time at a maximum output. 
     When the quick cooling operation is performed, the compressor may operate until the temperature detected by the defrosting temperature sensor is lower than a temperature during a normal operation. 
     The refrigerating compartment door may include: an ice making chamber in which an ice maker configured to make ice is accommodated, the ice making chamber being configured to define an insulation space; and a dispenser configured to communicate with the ice making chamber and dispense the made ice from the outside, wherein an ice making passage through which the freezing compartment and the ice making chamber may communicate with each other to supply the cool air for making the ice is provided in the cabinet. 
     At least a portion of the ice making passage may pass through a region of the refrigerating compartment. 
     The ice making passage may include: a supply duct configured to communicate with a space, in which the freezing compartment evaporator is disposed, so as to supply the cold air generated in the freezing compartment evaporator to the ice making chamber; and a return duct configured to communicate with the freezing compartment so as to collect air inside the ice making chamber into the freezing compartment, wherein openings of the supply duct and the return duct may be exposed through a wall surface of the refrigerating compartment and communicate with the inside of the ice making chamber in the state, in which the refrigerating compartment door is closed. 
     When the defrosting operation is performed, a refrigerant discharged from the compressor may be supplied to the freezing compartment evaporator, and the cold air generated in the freezing compartment evaporator may be supplied to the ice making chamber through the supply duct. 
     The filler heater may be configured to supply heat into the refrigerating compartment in the turn-on state. 
     The heat of the filler heater may be greater than that due to the cool air transferred into the refrigerating compartment through the ice making passage. 
     The filler may include a filler cover of which at least a portion is made of a steel material, and the filler heater may be in contact with the filler cover to heat the filler cover. 
     In another embodiment, a method for controlling a refrigerator, in which a refrigerating compartment is opened and closed by a pair of refrigerating compartment doors, and a filler configured to shield a gap between the pair of refrigerating compartment doors in a state in which the pair of refrigerating compartment doors are closed, includes: inputting a defrosting signal so that a defrosting operation starts during a normal operation; turning off a compressor according to the input of the defrosting signal and turning on a refrigerating compartment fan to circulate air inside the refrigerating compartment so as to pass through an evaporator; turning on the filler heater to supply heat into the refrigerating compartment; maintaining the turn-on state of the filler heater until a temperature detected by a defrosting temperature sensor that detects a temperature of the evaporator reaches a set temperature; and turning off the filler heater to end a defrosting operation so as to return to the normal operation when the temperature detected by the defrosting temperature sensor reaches the set temperature. 
     When the normal operation is performed, the compressor and the fan may be turned off so that the refrigerating compartment is maintained to a set temperature. 
     When the normal operation is performed, the filler hater may be controlled according to an external temperature. 
     The defrosting operation may include: performing a primary defrosting operation to apply heat until the temperature detected by the defrosting temperature sensor reaches a first set temperature in the state in which the filler heater is turned on; performing a quick cooling operation to turn off the filler heater when the primary defrosting operation is completed and to cool the inside of the refrigerator for a set time in a state in which the compressor is turned on; perform a secondary defrosting operation to turn off the compressor when the quick cooling operation is completed and apply heat until the temperature detected by the defrosting temperature sensor reaches a second set temperature higher than the detected first set temperature in the state in which the filler heater is turned on. 
     The second set temperature may be set to be higher than the first set temperature. 
     When the quick cooling operation is performed, the compressor may be driven at a maximum output. 
     The secondary defrosting operation may be performed for a longer time than that for the primary defrosting operation. 
     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. 
     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. 
     It will be understood that when an element or layer is referred to as being “on” another element or layer, the element or layer can be directly on another element or layer or intervening elements or layers. In contrast, when an element is referred to as being “directly on” another element or layer, there are no intervening elements or layers present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that, although the terms first, second, third, etc., may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. 
     Spatially relative terms, such as “lower”, “upper” and the like, may be used herein for ease of description to describe the relationship of one element or feature to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “lower” relative to other elements or features would then be oriented “upper” relative to the other elements or features. Thus, the exemplary term “lower” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Embodiments are described herein with reference to cross-section illustrations that are schematic illustrations of idealized embodiments (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
     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.