Patent Publication Number: US-2010115972-A1

Title: Refrigerator and control method of the same

Description:
TECHNICAL FIELD 
     The present invention relates to a refrigerator and a control method of the same, and more particularly, to a refrigerator that is capable of achieving smooth flow of cool air therein and improving cooling efficiency of a cooled evaporator and a control method of the same that is capable of controlling operation time of an evaporator and a fan, thereby improving cooling efficiency of the refrigerator. 
     BACKGROUND ART 
     Generally, a refrigerator is a freezing and refrigerating apparatus that repeatedly performs a refrigeration cycle in which refrigerant is compressed, condensed, expanded, and evaporated, for cooling the interior of the refrigerator to keep food fresh for a long time. A method of cooling a conventional refrigerator including a compressor for compressing low-temperature and low-pressure refrigerant into high-temperature and high-pressure refrigerant and an evaporator for performing heat exchange between the refrigerant, passing through the compressor, and external air, to perform the refrigeration cycle of the refrigerator will be described hereinafter with reference to  FIGS. 1 and 2 . 
     A refrigerator may be generally constructed in a structure in which a storage space performing a freezing function and a storage space performing a refrigerating function are divided from each other. Also, the refrigerator may be constricted in a cooling structure in which a single cooling apparatus, including an evaporator, is jointly used by both the freezing storage space and the refrigerating storage space or in another cooling structure in which two cooling apparatuses are separately provided to cool the refrigerating storage space and the freezing storage space, respectively. In the following, an example will be described in which a cooling apparatus is used to cool either the refrigerating storage space or the freezing storage space. 
     As shown in  FIGS. 1 and 2 , when a compressor  50  mounted in a refrigerator body is driven to compress gas refrigerant, the compressed gas refrigerant is condensed by a condenser, with the result that the temperature of the gas refrigerant lowers. After passing through the condenser, the gas refrigerant changes into low-temperature and low-pressure liquid refrigerant. After passing through an evaporator  10 , the liquid refrigerant changes into low-temperature and low-pressure gas refrigerant. This is achieved by evaporation in which the refrigerant, flowing in the evaporator  10 , takes heat away from air flowing around the evaporator  10 , whereby the refrigerant is evaporated. 
     The air cooled by the evaporation is discharged into storage chambers  40  through a first communication port  34  formed at the upper part of a duct  30 . The discharged cooled air cools the storage chambers  40  and is then introduced into the duct  30  through a second communication port  32  formed at the lower part of the duct  30 . The temperature in the upper part of the refrigerator is higher than that in the lower part of the refrigerator due to the difference in density of air based on the temperature of air in the storage chambers  40 . Consequently, the second communication port  32 , through which air to be heat-exchanged by the evaporator  10  is introduced, is located at a relatively high position. Also, the first communication port  34 , through which air introduced through the second communication port  32  and cooled by the evaporator  10  is discharged, is located at a position higher than the second communication port  32 . 
     However, the above-described structure of the duct  30  has the following problem. Cool air, generated through heat exchange by the evaporator  10 , does not flow in the refrigerator by convection, but flows in a circulation structure in which the cool air introduced through the second communication port  32  and discharged through the first communication port  34 . 
     However, such a circulation structure has a problem in that air circulation is induced only around the upper storage chamber  40 , whereby food in the storage chambers is not uniformly cooled. This local convection phenomenon increases the difference of temperature between the storage chambers. Furthermore, when the evaporator  10  or the compressor  50  is stopped, a cool air descending phenomenon occurs in which cool air gathers in the lower storage chamber  40 , which is located at the lower part of the refrigerator. In addition, the temperature of air in the upper storage chamber  40  increases. As a result, the difference of temperature between the storage chambers increases. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     An object of the present invention devised to solve the problem lies on a refrigerator and a control method of the same that is capable of achieving the circulation of air cooled by an evaporator throughout the refrigerator, thereby improving cooling efficiency. 
     Technical Solution 
     The object of the present invention can be achieved by providing a refrigerator including a storage chamber having a storage space defined therein, a duct partitioned from the storage chamber, the duct being provided at the upper part thereof with a first communication port communicating with the storage chamber, the duct being provided at the lower part thereof with a second communication port communicating with the storage chamber, an evaporator mounted in the duct, a fan mounted in the duct for blowing air from the duct into the storage chamber through the first communication port, and a controller for controlling the operation of the evaporator and the fan. 
     Preferably, the fan is configured such that the operation speed of the fan is controllable. 
     Preferably, the controller controls the fan to be kept operated for a predetermine time even after the evaporator is stopped. 
     Preferably, the controller controls the fan to be operated until the temperature of the evaporator reaches that of the air in the storage chamber. 
     In another aspect of the present invention, provided herein is a control method of a refrigerator, including a main cooling process of opening an evaporator and a fan to blow air in a duct into a storage chamber and cool the interior of the storage chamber and a sub cooling process of further operating the fan for a predetermined time, such that the remaining cool air in the evaporator and the duct is introduced into the storage chamber, after the operation of the evaporator is stopped. 
     Preferably, the sub cooling process includes a temperature comparison process of determining whether the temperature of the evaporator is equal to the temperature of air surrounding the evaporator and a fan stopping process of stopping the fan when it is determined at the temperature comparison process that the temperature of the evaporator is equal to the temperature of air surrounding the evaporator. 
     Advantageous Effects 
     In the refrigerator and the control method of the same according to the present invention, the circulation of air cooled by the evaporator is achieved throughout the refrigerator. Consequently, it is possible to reduce the difference of temperature between the storage chambers. Also, the fan is kept operated for a predetermined time, although the evaporator is stopped. Consequently, it is possible to improve cooling efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention, illustrate embodiments of the invention and together with the description serve to explain the principle of the invention. 
       In the drawings: 
         FIGS. 1 and 2  are sectional views illustrating the structure of a conventional refrigerator. 
         FIG. 3  is a front sectional view illustrating a refrigerator according to the present invention. 
         FIG. 4  is a side sectional view of the refrigerator according to the present invention. 
         FIG. 5  is a view illustrating the operation of a fan and a compressor in accordance with a control method of a refrigerator according to the present invention. 
         FIG. 6  is a flow chart illustrating processes of the control method of the refrigerator according to the present invention. 
     
    
    
     MODE FOR THE INVENTION 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. However, the present invention is not limited to the illustrated embodiments but may be implemented in other forms. The illustrated embodiments are rather given in order that the disclosure of the present invention is thorough and perfect, and the concept of the present invention is sufficiently communicated to those skilled in the art to which the present invention pertains. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
       FIGS. 3 and 4  are front and side sectional views respectively illustrating a refrigerator according to the present invention. The refrigerator according to the present invention includes a plurality of storage chambers  40  each defining a storage space therein, a compressor  50  for compressing refrigerant, an evaporator  10  mounted in a duct  30  for performing heat exchange between the refrigerant compressed by the compressor  50  and air suctioned from the storage chambers through evaporation, and a fan  20  for blowing the heat-exchanged air such that the heat-exchanged air is discharged out of the duct, i.e., toward the storage chambers  40 . The storage chambers  40 , the compressor  50 , the evaporator  10 , and the fan  20  are mounted in a refrigerator body  60 . 
     The storage chambers  40  are spaces partitioning the interior of the refrigerator. The number and size of the storage chambers  40  may be changed based on the size and use of the refrigerator. Also, although the respective storage chambers  40  are separated spaces in the refrigerator, air-flow holes (not shown) are formed at shelves of the respective storage chambers  40 . Consequently, air in the storage chambers  40  can freely flow. 
     The duct  30  of the refrigerator according to the present invention has communication ports for suction and discharge of air in the storage chambers  40 . Specifically, the duct  30  is provided at the upper part thereof with a first communication port  34 . Also, the duct  30  is provided at the lower part thereof with a second communication port  32 . 
     The first communication port  34  is a communication port through which air cooled by heat exchange of the evaporator  10  mounted in the duct  30  is discharged. The second communication port  32 , located at the lower part of the duct  30 , is a communication port through which air from the storage chambers is suctioned. Consequently, as shown in  FIGS. 3 and 4 , the duct of the refrigerator according to the present invention is constructed in a structure in which air is suctioned into the lower part of the duct, the air is cooled, and the cooled air is discharged from the upper part of the duct. 
     The suction of the air into the lower part of the duct and the discharge of the air from the upper part of the duct are possible by the directionality of the fan  20  mounted in the duct  30 . When the fan  20  rotates in the forward direction, air is blown toward the first communication port  34 . On the other hand, when the fan  20  rotates in the reverse direction, the flow direction of air is reversed. 
     Specifically, air flows in the refrigerator according to the present invention as follows. Air suctioned into the lower part of the duct  30  is cooled by the evaporator  10 , and is then discharged into the upper storage chamber  40 , which is located at the upper part of the refrigerator, by the fan  20 . Due to the difference of density caused by the difference of temperature, the cool air flows to the lower storage chamber  40 , which is located at the lower part of the refrigerator. The air, reaching the lower part of the refrigerator, is suctioned into the second communication port  32  formed at the lower part of the duct  30 . This air circulation eliminates the cool air descending phenomenon, which occurs when the temperature at the lower part of the refrigerator is higher than that at the upper part of the refrigerator, thereby reducing the difference of temperature between the respective storage chambers  40  in the refrigerator. 
       FIG. 5  is a graph illustrating operation time of the compressor  50  and the fan  20  in a control method of the refrigerator according to the present invention. The on-off operation for heat exchange by the evaporator  10  is not achieved by the operation of the evaporator  10  but may be decided based on the operation of the compressor that supplies refrigerant to be evaporated by the evaporator. That is, if the compressor  50  does not supply new refrigerant, the heat exchange capability of the evaporator gradually decreases. Consequently, the heat exchange operation by the evaporator  10  is assumed to be controlled by the on-off operation of the compressor  50 . 
     The compressor  50  of the refrigerator does not continue to operate but is alternately turned on and off at predetermine time intervals. The on-off operation of the compressor  50  may be reserved at predetermined time intervals. Alternatively, the temperature of the storage chambers may be detected, and the compressor  50  may be operated only when the detected temperature is higher than a predetermined temperature. However, the latter method is more reasonable because the storage chambers are efficiently cooled depending upon kinds and amount of food in the storage chambers  40 . 
     As shown in  FIG. 5 , the cooling of the storage chambers  40  of the refrigerator starts with the operation of the compressor  50  and the fan  20 . The operation of the compressor  50  of the refrigerator means the heat exchange by the evaporator. Consequently, when the compressor  50  is operated, air in the storage chamber, the temperature of which increases, is forcibly blown to the evaporator by the fan  20 , and the air is heat-exchanged by the evaporator, whereby the air is cooled. 
     In the control method of the refrigerator according to the present invention, the process of simultaneously operating the compressor  50  and the fan  20  is defined as a main cooling process. However, the power consumption of the compressor  50  is greater than that of the fan  20 . This is because the compressor  50  is a component having the highest power consumption in consideration of characteristics of the refrigerator requiring to be continuously operated. Consequently, the operation of the compressor  50  is decided based on the temperature of the storage chambers in the refrigerator. 
     The evaporator  10 , which evaporates the compressed refrigerant by heat exchange, is not supplied with new refrigerant necessary for heat exchange, when the operation of the compressor  50  is stopped. However, the temperature of the evaporator  10  is lower than the interior temperature of the storage chambers  40 , and therefore, it is possible to utilize cooling performance of the evaporator  10  for a while. 
     In the control method of the refrigerator according to the present invention, therefore, as shown in  FIG. 5 , the fan  20  is kept operated for a predetermined time t R  although the operation of the compressor  50  is stopped. The process of operating the fan  20  although the operation of the compressor  50  is stopped is defined as a sub cooling process. Consequently, the control method of the refrigerator according to the present invention is characterized in that the cooling process includes the main cooling process of simultaneously operating the compressor  50  and the fan  20  and the sub cooling process of stopping the operation of the compressor  50  and operating the fan  20 . 
       FIG. 6  is a flow chart illustrating the control method of the refrigerator according to the present invention. 
     The refrigerator starts to operate with the operation of the compressor  50  and the fan  20  (S 10 ). By the operation of the compressor  50  and the fan  20 , air suctioned into the duct  30  through the second communication port  32  formed at the duct  30  is heat-exchanged by the evaporator  10 . The compressor  50  continues to compress refrigerant until the temperature of the storage chambers reaches a predetermined temperature T min . The temperature of the storage chambers may be measured by a temperature sensor mounted in a specific storage chamber  40 . Alternatively, the average or maximum value of the temperature detected by a plurality of temperature sensors may be used. Consequently, when it is determined that the temperature T of the storage chambers reaches the predetermined temperature T min  of the storage chambers, at a process of comparing the temperature T of the storage chambers with the predetermined temperature T min  of the storage chambers (S 20 ), the compressor  50  of the refrigerator stops the refrigerant compressing operation. However, the blowing operation of the fan  20  continues although the compression operation of the compressor  50  is stopped (S 30 ). The comparison between the temperatures and the decision to operate the compressor  50  and the fan  20  are performed by a controller (not shown) of the refrigerator. 
     The subsequent process is a process of maintaining a state in which the operation of the compressor  50  is stopped and the fan  20  is operated for a predetermined time t r  (S 40 ). After the state in which only the fan  20  is operated is maintained for the predetermined time t r , the operation of the fan  20  is stopped (S 50 ). 
     In another embodiment of the control method of the refrigerator according to the present invention, the predetermined time t r  may be time necessary to make the temperature of the evaporator  10  equal to the temperature of air in the storage chambers. 
     The reason why the compressor  50  and the fan  20  are simultaneously operated, and then only the fan  20  is operated while the operation of the compressor is stopped is that the temperature of the evaporator  10  is lower than that of the storage chambers, and therefore, the low temperature of the evaporator may be used to cool the storage chambers  40 . However, when the temperature of the storage chambers  40  becomes equal to that of the evaporator  10 , there is no reason why the air from the storage chambers  40  should be forwarded to the evaporator  10  by the fan  20 . Consequently, when the temperature of the storage chambers  40  becomes equal to that of the evaporator  10 , the operation of the fan  20  is stopped. 
     The process of operating only the fan  20  while stopping the operation of the compressor  50  as described above is the sub cooling process. When the operation of the fan  20  is stopped, the sub cooling process is terminated. 
     When sub cooling process is terminated, the operation of both the compressor  50  and the fan  20  is stopped, and therefore, the temperature of the storage chambers  40  is not lowered any more. As a result, the temperature of the storage chambers  40  rises after the heat exchange with the evaporator  10  is stopped. However, the refrigerator has an object to keep food in the storage chambers  10  in a cooled state at less than a predetermined temperature. Consequently, when the temperature of the storage chambers exceeds the predetermined temperature, the compressor  50  and the evaporator  10  are operated again to cool the storage chambers  40 . 
     That is, the compressor  50  and the fan  20  are kept stopped until the temperature of the storage chambers  40  of the refrigerator reaches a predetermined limit temperature T MAX . However, when the temperature of the storage chambers  40  reaches a predetermined limit temperature T MAX , the procedure returns to S 10 . Through the above-described repetition, it is possible to maintain the storage chambers of the refrigerator at a temperature between the limit temperature T MAX  and the predetermined temperature T min . The less the difference between the limit temperature T MAX  and the predetermined temperature T min  is, the more uniformly food in the storage chambers  40  of the refrigerator is stored in a refrigerated state. 
     In the control method of the refrigerator according to the present invention, the compression speed of the compressor  50  and the rotation speed of the fan  20  may be electronically controlled. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.