Abstract:
The present invention relates to a cooling apparatus including a compressor, a condenser, a first expanding unit, a second expanding unit, a third expanding unit, a first evaporator, and a second evaporator; a first refrigerant circuit containing refrigerant discharged from the compressor and flowing into a suction side of the compressor through the condenser, the first expanding unit, the first evaporator, the second expanding unit and the second evaporator; a second refrigerant circuit containing the refrigerant passing through the condenser flowing into the suction side of the compressor through the third expanding unit and the second evaporator; a flow path control unit installed at a discharge side of the condenser, switching a refrigerant flow path so that the refrigerant passing through the condenser flows through at least one of the first and second refrigerant circuits; and a control unit selectively opening and closing the flow path control unit. The invention also relates to a method for controlling the apparatus.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a divisional of U.S. patent application Ser. No. 10/633,587, filed Aug. 5, 2003, now pending. This application also claims the benefit of Korean Patent Application No. 2002-76636, filed Dec. 4, 2002, Korean Patent Application No. 2003-8174, filed Feb. 10, 2003, and Korean Patent Application No. 2003-17221, filed Mar. 19, 2003, in the Korean Intellectual Property Office. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates, in general, to a cooling apparatus, and, more particularly, to a cooling apparatus which has two or more independently cooled cooling compartments.  
         [0004]     2. Description of the Related Art  
         [0005]     Generally, in a cooling apparatus having two or more cooling compartments, respective cooling compartments are separated by partition walls, and selectively opened and closed by doors. Further, an evaporator, which generates cool air, and a fan, which blows the cool air into each of the cooling compartments, are mounted in each cooling compartment. Since all cooling compartments are independently cooled by the operation of respective evaporators and fans, this cooling manner is called an independent cooling manner.  
         [0006]     As a representative cooling apparatus to which the independent cooling manner is applied, there is a refrigerator with a freezer compartment and a refrigerator compartment. The freezer compartment of the refrigerator is generally used to keep frozen food, and a typical suitable temperature thereof is approximately −18° C. The refrigerator compartment is used to keep normal food, not requiring freezing, at the normal temperature equal to or greater than 0° C. A typical suitable temperature in the refrigerator compartment is approximately 3° C.  
         [0007]     Although the suitable temperatures of the refrigerator and freezer compartments are different, as described above, evaporation temperatures of refrigerator and freezer compartment evaporators are the same in a conventional refrigerator. Therefore, a freezer compartment fan is continuously operated, and a refrigerator compartment fan is intermittently operated to blow cool air into the refrigerator compartment if necessary, thus preventing the internal temperature of the refrigerator compartment from excessively decreasing.  
         [0008]     As described above, even though the evaporation of refrigerant is continuously carried out in the refrigerator compartment evaporator, the operation of the refrigerator compartment fan is intermittently carried out, so cool air generated during an idle period of the refrigerator compartment fan is not supplied to the refrigerator compartment, but becomes a factor in forming frost on a surface of the refrigerator compartment evaporator. As frost is formed on the surface of the refrigerator compartment evaporator, evaporation efficiency of the refrigerator compartment evaporator deteriorates, thus deteriorating cooling efficiency of the refrigerator compartment. Further, even under conditions where cooling of only the refrigerator compartment is required, refrigerant must be compressed in consideration of an evaporation temperature required for the freezer compartment evaporator, thus unnecessarily increasing a load of the compressor.  
       SUMMARY OF THE INVENTION  
       [0009]     Accordingly, it is an aspect of the present invention to provide a time division multi-cycle type cooling apparatus, and a method of controlling the same, which may optimize temperatures of freezer and refrigerator compartments by controlling cooling operations of the refrigerator and the freezer compartments according to controlled a time intervals.  
         [0010]     Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.  
         [0011]     The foregoing and/or other aspects of the present invention are achieved by providing a cooling apparatus including a compressor, a condenser, a first expanding unit, a second expanding unit, a third expanding unit, a first evaporator, a second evaporator, first and second refrigerant circuits, a flow path control unit, and a control unit. The first refrigerant circuit contains refrigerant discharged from the compressor flowing into a suction side of the compressor through the condenser, the first expanding unit, the first evaporator, the second expanding unit and the second evaporator. The second refrigerant circuit contains the refrigerant passing through the condenser flowing into the suction side of the compressor through the third expanding unit and the second evaporator. The flow path control unit is installed at a discharge side of the condenser switching a refrigerant flow path so that the refrigerant passing through the condenser flows through at least one of the first and second refrigerant circuits. The control unit selectively opens and closes the flow path control unit. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings of which:  
         [0013]      FIG. 1  is a side sectional view of a refrigerator, according to an embodiment of the present invention;  
         [0014]      FIG. 2  is a view showing a refrigerant circuit of the refrigerator of  FIG. 1 ;  
         [0015]      FIG. 3  is a block diagram of a control system implemented on the basis of a control unit of the refrigerator of  FIG. 1 ;  
         [0016]      FIGS. 4A-4E  include timing charts showing a cooling mode control operation and a passive defrosting control operation of the refrigerator, according to an embodiment of the present invention;  
         [0017]      FIGS. 5A-5F  include timing charts showing a control operation performed when a temperature surrounding the refrigerator compartment, according to an embodiment of the present invention, is low (for example, equal to or less than 15° C.);  
         [0018]      FIG. 6  is a flowchart showing a humidity increase operating method of a refrigerator compartment when a temperature surrounding the refrigerator compartment, according to an embodiment of the present invention, is high;  
         [0019]      FIG. 7  is a flowchart showing a defrosting method of a refrigerator compartment evaporator depending on an operating time of an entire cooling mode in the refrigerator, according to an embodiment of the present invention;  
         [0020]      FIGS. 8A-8H  include timing charts showing a defrosting control operation of refrigerator and freezer compartment evaporators, with re-start of a compressor taken into consideration, in the refrigerator, according to an embodiment of the present invention; and  
         [0021]      FIGS. 9A-9F  include timing charts showing an independent defrosting control operation of only the freezer compartment evaporator of the refrigerator, according to an embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]     Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.  
         [0023]     Hereinafter, a cooling apparatus according to embodiments of the present invention will be described in detail with reference to FIGS.  1  to  9 F.  FIG. 1  is a side sectional view of a refrigerator according to an embodiment of the present invention. As shown in  FIG. 1 , a refrigerator compartment evaporator  106 , a refrigerator compartment fan motor  106   a , a refrigerator compartment fan  106   b  and a defrost heater  104   a  are installed in a refrigerator compartment  110 . Further, a freezer compartment evaporator  108 , a freezer compartment fan motor  108   a , a freezer compartment fan  108   b  and a defrost heater  104   b  are installed in a freezer compartment  120 . The defrost heaters  104   a  and  104   b  are used to eliminate frost formed on surfaces of the refrigerator compartment evaporator  106  and the freezer compartment evaporator  108 , respectively.  
         [0024]     Cool air generated from the refrigerator compartment evaporator  106  is blown into the refrigerator compartment  110  by the refrigerator compartment fan  106   b . Cool air generated from the freezer compartment evaporator  108  is blown into the freezer compartment  120  by the freezer compartment fan  108   b . Additionally, expanding devices (not shown) which depressurize and expand refrigerant are disposed at inlets of both the refrigerator compartment evaporator  106  and the freezer compartment evaporator  108 . Further, a condenser (not shown) is disposed at an outlet of the compressor  102 .  
         [0025]      FIG. 2  is a view showing a refrigerant circuit of the refrigerator of  FIG. 1 . As shown in  FIG. 2 , the compressor  102 , a condenser  202 , a first capillary tube  204 , the refrigerator compartment evaporator  106 , a second capillary tube  206 , and the freezer compartment evaporator  108  are connected to each other through a refrigerant pipe to form a single closed loop refrigerant circuit. Therefore, the refrigerator compartment evaporator  106  and the freezer compartment evaporator  108  are connected to each other through the second capillary tube  206 . Further, another closed loop refrigerant circuit passing through a third capillary tube  208  is formed between the condenser  202  and the freezer compartment evaporator  108 , so that refrigerant passing through the condenser  202  is depressurized and expanded by the third capillary tube  208  to flow into the freezer compartment evaporator  108 . Refrigerant flow control between the two refrigerant circuits is performed through a three-way valve  210  which is a flow path control device. In addition, in the refrigerant circuits of  FIG. 2 , there are further disposed a condenser fan motor  202   a  which drives a condenser fan  202   b , the refrigerator compartment fan motor  106   a  which drives the refrigerator compartment fan  106   b , and the freezer compartment fan motor  108   a  which drives the freezer compartment fan  108   b.    
         [0026]     If the two evaporators  106  and  108  are connected to each other using only a refrigerant pipe having the same inside diameter as that of a refrigerant pipe of a suction side of the compressor  102 , evaporation temperatures of the refrigerator compartment evaporator  106  and the freezer compartment evaporator  108  become equal in an entire cooling mode. In this case, if the evaporation temperature of the freezer compartment evaporator  108  is decreased in consideration of cooling of the freezer compartment  120 , frost is formed on the surface of the refrigerator compartment evaporator  106 . If the evaporation temperature of the freezer compartment evaporator  108  is increased so as to prevent frost from being formed, sufficient cooling of the freezer compartment  120  may not be performed. This problem is solved by connecting the freezer compartment evaporator  108  and the refrigerator compartment evaporator  106  to each other through the second capillary tube  206 , as shown in  FIG. 2 .  
         [0027]     The first capillary tube  204  depressurizes refrigerant passing through the condenser  202  to enable the refrigerant to be evaporated at an evaporation temperature required for the refrigerator compartment evaporator  106 . The second capillary tube  206  depressurizes the refrigerant passing through the refrigerator compartment evaporator  106  once more to enable the refrigerant to be evaporated at an evaporation temperature required for the freezer compartment evaporator  108 . This is because the evaporation temperature required for the freezer compartment evaporator  108  is lower than that required for the refrigerator compartment evaporator  106 . The third capillary tube  208  depressurizes the refrigerant passing through the condenser  202  to enable the refrigerant to be evaporated at the evaporation temperature required for the freezer compartment evaporator  108 . While the first and second capillary tubes  204  and  206  operate in such a way that the second capillary tube  206  secondarily depressurizes the refrigerant which has been primarily depressurized by the first capillary tube  204 , the third capillary tube  208  directly depressurizes the refrigerant passing through the condenser  202  to such an extent that the refrigerant may be evaporated at the evaporation temperature required for the freezer compartment evaporator  108 . For this operation, the third capillary tube  208  is designed so that resistance thereof is greater than that of the second capillary tube  206 . Consequently, depressurized degrees of refrigerant through the second and third capillary tubes  206  and  208  must be sufficient to obtain the evaporation temperature required for the freezer compartment evaporator  108 . Further, the inside diameter of the second capillary tube  206  is designed to be less than that of the refrigerant pipe of the suction side of the compressor  102  (for example, approximately 2 to 4 mm), so that the refrigerant is depressurized while passing through the second capillary tube  206 . If the inside diameter of the second capillary tube  206  is excessively large, the evaporation temperatures of the evaporators  106  and  108  are not greatly different, while if the inside diameter thereof is excessively small, excessively large resistance is generated in a flow of refrigerant, in which liquid and gas are mixed in the refrigerator compartment evaporator  106 , thus decreasing a cooling speed of the refrigerator compartment  110 .  
         [0028]     The refrigerator according to an embodiment of the present invention as constructed above provides various cooling modes through the control of a control unit such as a microcomputer.  FIG. 3  is a block diagram of a control system implemented on the basis of a control unit  302  provided in the refrigerator according to an embodiment of the present invention. As shown in  FIG. 3 , an input port of the control unit  302  is connected to a key input unit  304 , a freezer compartment temperature sensing unit  306 , a refrigerator compartment temperature sensing unit  308 , and a refrigerator compartment evaporator temperature sensing unit  322 . The key input unit  304  includes a plurality of function keys which relate to the setting of operating conditions of the refrigerator, such as the cooling mode setting and the desired temperature setting. The freezer compartment temperature sensing unit  306  and the refrigerator compartment temperature sensing unit  308  sense the temperatures of the freezer compartment  120  and the refrigerator compartment  110 , respectively, and provide the sensed temperatures to the control unit  302 . The refrigerator compartment evaporator temperature sensing unit  322  senses a refrigerant evaporation temperature of the refrigerator compartment evaporator  106 , and provides the sensed refrigerant evaporation temperature to the control unit  302 .  
         [0029]     An output port of the control unit  302  is connected to a compressor driving unit  312 , a freezer compartment fan driving unit  314 , a refrigerator compartment fan driving unit  316 , a three-way valve driving unit  318 , a defrost heater driving unit  320 , and a display unit  310 . The driving units  312 ,  314 ,  316 ,  318 , and  320  drive the compressor  102 , the freezer compartment fan motor  108   a , the refrigerator compartment fan motor  106   a , the three-way valve  210  and the defrost heaters  104   a  and  104   b , respectively. The display unit  310  displays operating states, various set values, and temperatures of the cooling apparatus and the like.  
         [0030]     The control unit  302  implements various cooling modes by controlling the three-way valve  210  to circulate the refrigerant through at least one of the two refrigerant circuits of  FIG. 2 . As two possible representative cooling modes which may be implemented in the refrigerator according to an embodiment of the present invention, a first cooling mode is the entire cooling mode, and a second cooling mode is the freezer compartment cooling mode. The entire cooling mode is an operating mode which allows both the refrigerator compartment  110  and the freezer compartment  120  to be cooled. The control unit  302  opens only a first valve  210   a  of the three-way valve  210  to implement the entire cooling mode, in which refrigerant discharged from the condenser  202  is circulated through the first capillary tube  204 , the refrigerator compartment evaporator  106 , the second capillary tube  206 , and the freezer compartment evaporator  108 . The freezer compartment cooling mode is an operating mode which allows only the freezer compartment  120  to be independently cooled. The freezer compartment cooling mode is implemented by allowing the control unit  302  to open only a second valve  210   b  of the three-way valve  210 , in which refrigerant discharged from the condenser  202  is circulated through only the third capillary tube  208  and the freezer compartment evaporator  108 .  
         [0031]     As described below, there are pressure variations of the refrigerant occurring in the entire cooling mode and the freezer compartment cooling mode of the refrigerator according to an embodiment of the present invention, and evaporation temperature variations of the evaporators  106  and  108 , depending upon the pressure variation of the refrigerant. If the first valve  210   a  of the three-way valve  210  is opened, as in the entire cooling mode (the second valve  210   b  is closed), refrigerant discharged from the condenser  202  is primarily depressurized by the first capillary tube  204 , and primarily evaporated by the refrigerator compartment evaporator  106 . The refrigerant, which has been primarily evaporated by the refrigerator compartment evaporator  106 , is secondarily depressurized while passing through the second capillary tube  206 , and then secondarily evaporated by the freezer compartment evaporator  108 .  
         [0032]     By the staged depressurization of the refrigerant through the first and second capillary tubes  204  and  206  in the entire cooling mode, unique evaporation temperatures required for the evaporators  106  and  108  may be obtained, so overcooling of the refrigerator compartment evaporator  106 , occurring when the evaporation temperature of the refrigerator compartment evaporator  106  is the same as that of the freezer compartment evaporator  108 , and the formation of frost, due to the overcooling of the refrigerator compartment evaporator  106 , are remarkably decreased.  
         [0033]     As described above, a typical suitable temperature of the freezer compartment is approximately −18° C., and a typical suitable temperature of the refrigerator compartment is approximately 3° C. Thus, since the difference between the suitable temperatures of the freezer and refrigerator compartments is large, sufficient cooling of the freezer compartment may not be achieved if the evaporation temperatures of the evaporators are increased to suppress the overcooling of the refrigerator compartment. In the cooling apparatus according to an embodiment of the present invention, if the cooling of the freezer compartment  120  is insufficient, the freezer compartment  120  is independently cooled at a low evaporation temperature, thus enabling the temperature of the freezer compartment  120  to promptly reach a target temperature.  
         [0034]     The freezer compartment cooling mode is a mode for allowing only the freezer compartment  120  to be independently cooled. In this mode, the second valve  210   b  of the three-way valve  210  is opened (first valve  210   a  is closed), and refrigerant discharged from the condenser  202  flows into the freezer compartment evaporator  108  through the third capillary tube  208 . In the freezer compartment cooling mode, refrigerant is depressurized to a lower pressure by the third capillary tube  208  and then evaporated by the freezer compartment evaporator  108 . Through additional depressurization of the refrigerant by the third capillary tube  208 , the evaporation temperature of the freezer compartment evaporator  108  becomes lower than that of the refrigerator compartment evaporator  106 .  
         [0035]     In the refrigerator according to an embodiment of the present invention, even though the evaporation temperatures of the evaporators  106  and  108  are different to minimize the formation of frost, frost may be accumulated on the surface of the refrigerator compartment evaporator  106  due to its operation over a long time. The time division multi-cycle type cooling apparatus of the present invention eliminates the accumulated frost, and provides moisture generated during the frost eliminating process to the refrigerator compartment  110  to increase the humidity of the refrigerator compartment  110  through control operations, which will be described later.  
         [0036]      FIGS. 4A-4E  include timing charts showing a cooling mode control operation and a passive defrosting control operation of the refrigerator according to an embodiment of the present invention. As shown in  FIGS. 4A-4E , in an initial operating state in which the refrigerator, which was turned off, is turned on and supplied with power, the first valve  210   a  is opened and the second valve  210   b  is closed to initially perform the entire cooling mode. After that, the first valve  210   a  is closed, and the second valve  210   b  is opened to perform the freezer compartment cooling mode. Thus, the refrigerator according to an embodiment of the present invention always performs the entire cooling mode first when the refrigerator is supplied with power, and then switches to the freezer compartment cooling mode. If the freezer compartment cooling mode is first performed, the cooling of the refrigerator compartment  110  begins too late, so the entire cooling mode is first performed in consideration of the cooling speed of the refrigerator compartment  110 . Alternatively, it is possible to simultaneously perform the entire cooling mode and the freezer compartment cooling mode. However, in this case, while a load of the compressor is greatly increased, the cooling speed is similar to that of the entire cooling mode, so this method is not effective.  
         [0037]     When the operation of the compressor  102  is stopped after the freezer compartment cooling mode, the first valve  210   a  of the three-way valve  210  is opened, and the second valve  210   b  is closed, for a time t1 shown in  FIGS. 4A-4E . After the time t1 has elapsed, the second valve  210   b  is opened again. In the freezer compartment cooling mode, the refrigerator compartment evaporator  106  has almost a vacuum state, which is free of refrigerant. Therefore, if the first valve  210   a  is opened after the operation of the compressor  102  is stopped, high temperature refrigerant which has been previously compressed and discharged by the compressor  102  flows into the refrigerator compartment evaporator  106  having almost a vacuum state therein. As a result, the refrigerant flowing into the refrigerator compartment evaporator  106  is depressurized to some degree by the first capillary tube  204  for the certain time t1 immediately after the operation of the compressor  102  is stopped, thus decreasing the refrigerant evaporation temperature of the refrigerator compartment evaporator  106 . If the refrigerator compartment fan  106   b  is operated for the time t1, the cooling of the refrigerator compartment  110  may be additionally performed.  
         [0038]     However, if the temperature surrounding the refrigerator compartment is less than a preset temperature (for example, 15° C.) at the time the entire cooling mode is completed, the temperature of the refrigerator compartment  110  may still be decreased to be equal to or less than a target temperature.  FIGS. 5A-5F  include timing charts showing a control operation performed when the temperature surrounding the refrigerator compartment according to an embodiment of the present invention is low (for example, equal to or less than 15° C.). As shown in  FIGS. 5A-5F , if the temperature surrounding the refrigerator compartment is less than the preset temperature (for example, equal to or less than 15° C.) when the operation of the compressor  102  is stopped after the freezer compartment cooling mode, the defrost heater  104   a  of the refrigerator compartment evaporator  106  is operated for a first preset time t2 after the first valve  210   a  is opened and the second valve  210   b  is closed. In this case, even though the temperature surrounding the refrigerator compartment has decreased to be equal to or less than 0° C., the target temperature of the refrigerator compartment  110  may be maintained. At this time, a heating temperature of the defrost heater  104   a  is limited to a preset temperature or less of the refrigerator compartment  110 , thus preventing the temperature of the refrigerator compartment  110  from exceeding the target temperature due to heating by the defrost heater  104   a . After that, if the time t2 has elapsed, the second valve  210   b  is opened again to stop the operation of the defrost heater  104   a , and thereafter the refrigerator compartment fan  106   b  is operated for a time t3. In this case, the reason for closing the second valve  210   b  and then opening it again is to equalize the pressure of the refrigerant over the entire refrigerant circuits by opening both the first and second valves  210   a  and  210   b.    
         [0039]     In the refrigerator according to an embodiment of the present invention, if the temperature surrounding the refrigerator compartment is equal to or greater than a certain temperature (for example, 15° C.) when the entire cooling mode has been completed, there is performed a humidity increasing operation to eliminate frost formed on the refrigerator compartment evaporator  106 . The moisture generated at the time of eliminating the frost is simultaneously blown into the refrigerator compartment  110 , to increase the humidity of the refrigerator compartment  110 , by operating the refrigerator compartment fan  106   b  for a certain time. However, if the humidity increasing operation of the refrigerator compartment  110  is performed when the temperature surrounding the refrigerator compartment is excessively low, dew condensation forms in the refrigerator compartment  110 , so the humidity increasing operation is performed only when the temperature surrounding the refrigerator compartment is equal to or greater than a certain temperature.  FIG. 6  is a flowchart of a humidity increasing operating method of the refrigerator compartment performed when the temperature surrounding the refrigerator compartment according to an embodiment of the present invention is high. As shown in  FIG. 6 , if the entire cooling mode has been completed in  702  and  704 , it is determined whether the temperature surrounding the refrigerator compartment is equal to or greater than a preset temperature in  706 . If it is determined that the temperature surrounding the refrigerator compartment is equal to or greater than the preset temperature, the refrigerator compartment fan  106   b  is operated for a certain time to perform the humidity increasing operation of the refrigerator compartment  110  in  708 , and thereafter an operating mode is switched to the freezer compartment cooling mode in  710 .  
         [0040]     If the cooling load of the refrigerator compartment  110  is continuously increased due to frequent opening of a door, etc., in the entire cooling mode, in which both the refrigerator compartment  110  and the freezer compartment  120  are cooled, the operating time of the entire cooling mode is inevitably lengthened so as to maintain a target temperature of the refrigerator compartment  110 . If the operating time of the entire cooling mode is excessively long, frost formed on the surface of the refrigerator compartment evaporator  106  is accumulated, greatly deteriorating cooling efficiency of the refrigerator compartment  110 . Therefore, if a continuous operating time of the entire cooling mode is increased to be equal to or greater than a preset time, the refrigerator compartment fan  106   b  is operated to perform a defrosting operation of the refrigerator compartment evaporator  106 .  FIG. 7  is a flowchart of a defrosting method of the refrigerator compartment evaporator depending on the operating time of the entire cooling mode in the refrigerator according to an embodiment of the present invention. As shown in  FIG. 7 , the time for which the entire cooling mode progresses is counted while the entire cooling mode is performed in  802  and  804  (using a counter provided in the control unit). If the progress time of the entire cooling mode is equal to or greater than a preset time in  806 , the operating mode is switched from the entire cooling mode to the freezer compartment cooling mode in  808 . Thereafter, the refrigerator compartment fan  106   b  is operated to perform a defrosting operation of the refrigerator compartment evaporator  106  in  810 . If the operating time of the refrigerator compartment fan  106   b  exceeds a preset time in  812 , the operating mode is switched again from the freezer compartment cooling mode to the entire cooling mode to perform a cooling operation in  814 .  
         [0041]      FIGS. 8A-8H  include timing charts showing a defrosting control operation of the refrigerator compartment evaporator  106  and the freezer compartment evaporator  108 , with re-start of the compressor taken into consideration, in the refrigerator according to an embodiment of the present invention. Simultaneous defrosting operations of the refrigerator compartment evaporator  106  and the freezer compartment evaporator  108 , performed during an idle period of the compressor  102 , are carried out by operating the defrost heaters  104   a  and  104   b , respectively provided in the evaporators  106  and  108 , after the operations of the compressor  102  and the fans  106   b  and  108   b  are stopped, and both the first and second valves  210   a  and  210   b  of the three-way valve  210  are opened. During this simultaneous defrosting process, the pressure of the refrigerant is increased due to the heating by the defrost heaters  104   a  and  104   b . In this case, if the pressure of the refrigerant is excessively high, re-starting of the compressor  102  is not performed smoothly after the defrosting operation has been completed. Therefore, as shown in  FIGS. 8A-8H , the defrost heaters  104   a  and  104   b , respectively provided in the evaporators  106  and  108 , are operated to eliminate formed frost. After the operations of the defrost heaters  104   a  and  104   b  have been completed, the condenser fan  202   b  and the freezer compartment fan  108   b  are operated for a certain time to decrease the temperature of the refrigerant heated by the defrost heaters  104   a  and  104   b , thus decreasing the pressure of the refrigerant. In this way, the pressure of the refrigerant is decreased to enable the re-starting of the compressor  102  to be performed more smoothly. While the defrost heaters  104   a  and  104   b  are operated, the condenser fan  202   b  and the freezer compartment fan  108   b  are not operated, so as to increase heating effect of the defrost heaters  104   a  and  104   b.    
         [0042]      FIGS. 9A-9F  include timing charts showing a control method performed when only the freezer compartment evaporator is independently defrosted during an idle period of the compressor in the refrigerator according to an embodiment of the present invention. As shown in  FIGS. 9A-9F , the independent defrosting operation of only the freezer compartment evaporator  108  is performed when the first valve  210   a  of the three-way valve  210  is closed and the second valve  210   b  is opened, after the compressor  102  and the evaporator fans  106   b  and  108   b  have been stopped. If the second valve  210   b  is opened, high temperature refrigerant of the condenser  202  flows into the freezer compartment evaporator  108  through the third capillary tube  208  to increase the temperature. In this case, the load of the defrost heater  104   b  of the freezer compartment  120  is decreased, thus reducing power consumption due to the operation of the defrost heater  104   b . After the defrosting operation of the freezer compartment evaporator  108  has been completed, both the first and second valves  210   a  and  210   b  of the three-way valve  210  are opened for a certain time t5 to equalize the pressure of refrigerant over the respective refrigerant circuits before the compressor  102  is re-started. If the time t5 has elapsed and the pressure equalization of the refrigerant circuits is achieved in some degree, the compressor  102  is re-started.  
         [0043]     As is apparent from the above description, the present invention provides a time division multi-cycle type cooling apparatus and method for controlling the same, which has the following advantages. First, in the case of a refrigerator, a refrigerator compartment and a freezer compartment are cooled at different evaporation temperatures, or only the freezer compartment is independently cooled, thus obtaining cooling temperatures suitable for the refrigerator and freezer compartments, respectively, and suppressing overcooling of the refrigerator compartment. Further, the present invention may perform a defrosting operation of a refrigerator compartment evaporator by operating a refrigerator compartment fan and (or additionally) a defrost heater in an operating mode in which only the freezer compartment is independently cooled, and increase the humidity of the refrigerator compartment by blowing moisture generated during a defrosting process into the refrigerator compartment. Further, in an embodiment of the present invention, a refrigerator compartment fan is operated for a certain time to eliminate frost formed on the surface of the refrigerator compartment evaporator immediately after the operation of the compressor is stopped, thus solving a frost formation problem occurring due to the evaporation of refrigerant in the refrigerator compartment evaporator immediately after the compressor is stopped.  
         [0044]     In addition, in the case of an air conditioner system having a plurality of indoor units, different evaporation temperatures are assigned to indoor units requiring different cooling capacities, thus achieving effective air conditioning.  
         [0045]     Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.