Patent Publication Number: US-2012023974-A1

Title: Refrigerator and method for controlling the same

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application Nos. 10-2010-0073368 filed on Jul. 29, 2010 and 10-2010-0073369 filed on Jul. 29, 2010, which are hereby incorporated by reference as if fully set forth herein. 
     BACKGROUND OF THE DISCLOSURE 
     1. Field of the Disclosure 
     The present invention relates to refrigerators, and more particularly, to a refrigerator which can measure an amount of frost on an evaporator in real time and determine a frost removing time; and a method for controlling the same. 
     2. Discussion of the Related Art 
     In general, the refrigerator is an appliance for storing goods at a low temperature for long time fresh storage of food, wherein the goods are stored in a frozen state or a refrigerated state depending on a state of the goods intended to store. 
     Cold air to be supplied to the refrigerator is produced by heat exchange of refrigerant which is kept supplied to the refrigerator as a cycle of compression-condensation-expansion-evaporation is performed repeatedly, and provided to an inside of the refrigerator uniformly by convection, enabling to store the food in the refrigerator at a desired temperature. 
     In the refrigerators, there are general type refrigerators, side by side door type refrigerators, and bottom freezer type refrigerators depending on a structure of a refrigerating chamber and a freezing chamber. 
     The general type refrigerator has a structure in which the freezing chamber is positioned on an upper side and the refrigerating chamber is positioned on a lower side, and the side by side door type refrigerator has a structure in which the freezing chamber and the refrigerating chamber are arranged side by side in a left to right direction. 
     The bottom freezer type refrigerator is a type currently used in the U.S.A. and the Europe mostly, and has the refrigerating chamber greater than the freezing chamber positioned on the upper side while the freezing chamber is positioned on the lower side. 
     In the meantime, the refrigerator is provided with a body having at least one storage space for low temperature storage of food and a door rotatably mounted to the body for selective opening/closing of the storage space. 
     In general, the storage space of the refrigerator is partitioned into the freezing chamber and the refrigerating chamber, and, in rear of the storage space, there are an evaporator for making heat exchange with air in the storage space to produce cold air, and a fan for introducing the air from the storage space to the evaporator, and blowing the cold air having heat exchanged thus to the storage space, again. 
     In the meantime, the evaporator in the cycle makes heat exchange between the air circulating in the storage space and the refrigerant, to form condensed water on a surface thereof in a process of making heat exchange with the air which circulates the storage space because a surface temperature of the evaporator is lower than a room temperature. 
     In this instance, the condensed water freezes on the surface of the evaporator to turn to frost, to cause a problem of poor heat exchange efficiency of the evaporator when the frost accumulates on the surface of the evaporator. 
     In order to solve the problem, a method is used, in which a frost removal heater is mounted to one side of the evaporator to operate the same at fixed time intervals. 
     Above frost removal operation is performed taking operation times of the refrigerating chamber and the freezing chamber and a door open time into account, regardless of an actual amount of accumulation of the frost. 
     However, the frost removal time predicted with reference to the door open time and the operation times of the storage space has a problem in that, in actual conditions of use of the refrigerator, the frost removal heater comes into operation at a time no frost removal is required actually, or the frost removal heater does not come into operation even if the frost removal is required. 
     SUMMARY OF THE DISCLOSURE 
     Accordingly, the present invention is directed to a refrigerator and a method for controlling the same. 
     An object of the present invention is to provide a refrigerator which can measure an amount of frost on an evaporator in real time and determine a frost removing time; and a method for controlling the same. 
     Additional advantages, objects, and features of the disclosure will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a refrigerator includes a body having at least one storage space for low temperature storage, a compressor in the body for compressing refrigerant, an evaporator for making heat exchange between the refrigerant from the compressor and air in the storage space, a frost removal heater for removing frost from the evaporator, an optical sensor having a light emitting unit for directing a light to the evaporator and a light receiving unit for receiving the light from the light emitting unit, and a control unit for controlling operation of the frost removal heater with reference to a quantity of the light received at the light receiving unit. 
     And, the optical sensor can be arranged over or under the evaporator. 
     In this instance, the control unit can put the frost removal heater into operation only if the quantity of the light received at the light receiving unit is greater than a reference value. 
     On the other hand, the optical sensor can be arranged such that the evaporator is positioned between the light emitting unit and the light receiving unit. 
     In this instance, the control unit can put the frost removal heater into operation only if the quantity of the light received at the light receiving unit is smaller than a reference value. 
     And, the light emitting unit of the optical sensor can include an infrared light emitting diode. 
     And, the refrigerator can further include a bracket which connects the optical sensor to the evaporator. 
     And, the bracket can include a body which is an extension in a height direction of the evaporator and has at least one slot for placing the tube therein, and a mounting portion which is an inward bent from an end of the body for mounting the optical sensor thereto such that the optical sensor faces the evaporator. 
     And, the bracket can have an angle shaped section. 
     And, the control unit can put the frost removal heater into operation only if the quantity of the light received at the light receiving unit is greater than a reference value. 
     Different from this, the bracket can include a body which is an extension in a height direction of the evaporator and has at least one slot for placing the tube therein, and a mounting portion which is inward bents from both ends of the body for mounting the optical sensor thereto such that the optical sensor faces the evaporator. 
     And, the body can have one end with the light emitting unit mounted thereto and the other end with the light receiving unit mounted thereto. 
     And, the bracket has a channel shaped section. 
     And, the control unit can put the frost removal heater into operation only if the quantity of the light received at the light receiving unit is smaller than a reference value. 
     In another aspect of the present invention, a method for controlling a refrigerator includes the steps of (a) directing a light to an evaporator, (b) receiving the light passed through the evaporator, and (c) removing frost with reference to a quantity of the light received thus. 
     And, the step (a) can include the step of directing a light with an infrared light emitting diode. 
     And, the step (b) can include the step of receiving a light reflected at the evaporator. 
     In this instance, the frost removal can be performed if the quantity of the light reflected thus is greater than a reference value. 
     Different from this, the step (a) can include the step of receiving a light passed through the evaporator. 
     In this instance, the frost removal can be performed if the quantity of the light passed thus is smaller than a reference value. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the disclosure and together with the description serve to explain the principle of the disclosure. In the drawings: 
         FIG. 1  illustrates a perspective view of a refrigerator in accordance with a preferred embodiment of the present invention, showing a state in which one of doors is opened. 
         FIG. 2  illustrates a section of key parts of the refrigerator in  FIG. 1 . 
         FIG. 3  illustrates a block diagram of a control unit in a refrigerator in accordance with a preferred embodiment of the present invention. 
         FIGS. 4 to 7  illustrate schematic views showing mounting positions of an optical sensor in a refrigerator in accordance with a preferred embodiment of the present invention, respectively. 
         FIGS. 8A and 8B  illustrate graphs for describing a method for determining a frost removing time in accordance with a preferred embodiment of the present invention. 
         FIG. 9  illustrates a flow chart showing the steps of a method for controlling a refrigerator in accordance with a preferred embodiment of the present invention. 
     
    
    
     DESCRIPTION OF SPECIFIC EMBODIMENTS 
     Reference will now be made in detail to the specific embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
     A refrigerator and a method for controlling the same in accordance with a preferred embodiment of the present invention will be described with reference to the attached drawings. The attached drawings are illustrative, and only provided for describing the present invention in more detail, but do not limit technical scopes of the present invention. 
     And, identical or equivalent elements will be given the same reference numerals regardless of drawing numbers, repetitive description thereof will be omitted, and for convenience of description, sizes and shapes of the elements can be exaggerated or reduced. 
     Though terms including ordinal numbers, such as first or second, can be used for describing various elements, the elements are not limited by the terms, and are used only for making one element distinctive from other elements. 
       FIG. 1  illustrates a perspective view of a refrigerator  1  in accordance with a preferred embodiment of the present invention, showing a state in which one of doors is opened, and  FIG. 2  illustrates a section of key parts of the refrigerator in  FIG. 1 . 
     Though a refrigerator  1  in accordance with a preferred embodiment of the present invention is applicable to all refrigerators of various types (For an example, a general type, a side by side door type, or a bottom freezer type), the refrigerator  1  will be described taking the side by side door type refrigerator having a freezing chamber and a refrigerating chamber positioned side by side in a left to right direction to be opened/closed by respective doors selectively as an example. 
     The refrigerator in accordance with a preferred embodiment of the present invention includes a body  10  having at least one storage space  40  for low temperature storage, a compressor  90  in the body  10  for compressing refrigerant, an evaporator  60  for making heat exchange between the refrigerant from the compressor  90  and air in the storage space  40 , a frost removal heater  70  for removing frost from the evaporator  60 , an optical sensor (Not shown) having a light emitting unit for directing a light to the evaporator  60  and a light receiving unit for receiving the light from the light emitting unit, and a control unit (Not shown) for controlling operation of the frost removal heater  70  with reference to a quantity of the light received at the light receiving unit. 
     Referring to  FIGS. 1 and 2 , the refrigerator  1  in accordance with a preferred embodiment of the present invention includes a body  10  which provides a space  40  for storage of food and food containers at a low temperature and an exterior of the refrigerator, wherein the body  10  has a hexahedral shape substantially, with an opened front for placing the food and the food containers therein. 
     The body  10  of the refrigerator  1  can also include an outer case (No reference numeral is given) and at least one inner case (No reference numeral is given) in the outer case for providing the storage space for refrigerated or frozen storage of the food. 
     The doors  20  and  30  are rotatably mounted to the opened front of the body  10  for selective opening/closing of the opened front of the body  10 .  FIG. 1  illustrates a side by side door type refrigerator in a case a first door  20  and a second door  30  are mounted to the body  10  for opening/closing a left side storage space and a right side storage space, respectively. 
     And, currently, for convenience of use of the refrigerator  1 , various functions are added to the refrigerator, and in order to embody such functions, the refrigerator  1  can further include a dispenser  21  provided to the door  20  or  30  for dispensing purified water or ice to an outside of the refrigerator directly, and a home bar  31  for placing or storage of a certain amount of food or food containers therein, conveniently. 
     And, on a rear of the door  30 , at least one basket  33  and one storage box  32  can be mounted. 
     And, in a case of the side by side door type refrigerator  1 , the body  10  has an inside space partitioned into the left side space and the right side space, wherein, in general, the left side space serves as a freezing chamber (Not shown) for holding the food or the food container at a sub-zero temperature, and the right side space serves as a refrigerating chamber  40  for holding the food or the food container at a temperature higher than a zero degree. 
     The freezing chamber is used for long time storage of the food by freezing the food at the sub-zero temperature, and the refrigerating chamber  40  is maintained at a temperature lower than a room temperature for fresh storage of the food. 
     The freezing chamber and the refrigerating chamber  40  have a plurality of shelves  41  provided to inside spaces thereof for placing the food or the food container thereon, thereby partitioning the inside spaces of the freezing chamber and refrigerating chamber  40  into a plurality of tiers to form a plurality of storage spaces. And, the freezing chamber and the refrigerating chamber  40  can have drawers  42  for holding food, such as vegetable and fruit. 
     The refrigerator stores not only the vegetable and the fruit, but also meat, fish, various food materials and cooked food, and since the body  10  has the plurality of storage spaces with the shelves and the drawers, the food can be stored separately for each kind of food. 
     And, in rear of the storage space  40 , there is a cold air producing chamber (No reference numeral is given) having the evaporator  60  placed therein for making heat exchange between the refrigerant and the air in the storage space. The cold air producing chamber has a fan  50  for discharging the cold air produced by the evaporator  60  to the storage space  40 , the frost removal heater  70  for removing frost from the evaporator  60 , and a drain portion  80  under the frost removal heater  70  for collecting water of the frost. 
       FIG. 3  illustrates a block diagram of a control unit in a refrigerator in accordance with a preferred embodiment of the present invention,  FIGS. 4 to 7  illustrate schematic views showing mounting positions of an optical sensor in a refrigerator in accordance with a preferred embodiment of the present invention respectively, and  FIGS. 8A and 8B  illustrate graphs for describing a method for determining a frost removing time in accordance with a preferred embodiment of the present invention. 
     As described before, the evaporator  60  in the cycle of the refrigerator  1  makes heat exchange between the air circulating the storage space and the refrigerant, and since the surface temperature of the evaporator  60  is lower than the room temperature, the condensed water is formed on the surface of the evaporator  60  in a heat exchange process with the air which circulates the storage space. 
     In this instance, the condensed water freezes on the surface of the evaporator  60  into the frost, and if the frost accumulates on the surface of the evaporator  60 , a problem causes in that heat exchange efficiency of the evaporator  60  becomes poor. 
     In order to solve the problem, the frost removal heater  70  is mounted to one side of the evaporator  60 , for removing the frost from the surface of the evaporator  60  by operating the frost removal heater  70 . 
     If the frost is formed on the evaporator  60 , the heat exchange efficiency of the evaporator  60  becomes poor. And, it is important to detect an amount of the frost on the evaporator  60  in real time to determine an accurate frost removal time for reducing power consumption caused by unnecessary frost removal operation and a number of temperature rise times of the storage space. 
     Referring to  FIG. 3 , the optical sensor  100  includes the light emitting unit  110  for directing the light to the evaporator and the light receiving unit  120  for receiving the light from the light emitting unit  110 . 
     As one embodiment, the optical sensor  100  senses a quantity of the light which is directed to the evaporator, reflected at the frost on the evaporator, and received at the light receiving unit  120 , and the control unit  200  determines a frost removing time with reference to the quantity of light received at the light receiving unit  120 , and puts the frost removing heater  70  into operation. 
     For an example, since the greater the quantity of the frost on the evaporator  60 , the greater the quantity of the light reflected at the frost, upon comparing the quantity of the light reflected thus to a reference value measured in advance experimentally, if the quantity of the light is greater than the reference value, the control unit  200  can put the frost removing heater  70  into operation. 
     And, the light emitting unit  110  of the optical sensor  100  can be a light source for emitting a light of an infrared wavelength or an ultrasonic wavelength, preferably, can include an infrared light emitting diode. 
     Referring to  FIG. 4 , the evaporator  60  can include a refrigerant tube  110  for the refrigerant to flow therethrough and a plurality of fins  62  in contact with the refrigerant tube for increasing a heat exchange area. 
     The optical sensor can be mounted over the evaporator  60 . That is, both the light emitting unit  110  and the light receiving unit  120  can be arranged at positions spaced predetermined distances away from a top of the evaporator  60 , respectively. 
     The optical sensor  100  senses the quantity of the light which is directed to evaporator, reflected at the frost F on the evaporator, and received at the light receiving unit  120 , and the control unit  200  determines a frost removing time with reference to the quantity of light received at the light receiving unit  120 , and puts the frost removing heater  70  into operation. 
     Referring to  FIGS. 4 and 8A , since the greater the quantity of the frost on the evaporator  60 , the greater the quantity of the light reflected at the frost, upon comparing the quantity of the light to the reference value S 1  measured in advance experimentally, if the quantity of the light is greater than the reference value S 1 , the control unit  200  can put the frost removing heater  70  into operation. 
     Referring to  FIG. 5 , the optical sensor  100  can be arranged under the evaporator  60 . That is, both the light emitting unit  110  and the light receiving unit  120  can be arranged at positions spaced predetermined distances away from a bottom of the evaporator  60 , respectively. 
     Even in a case the optical sensor  100  is arranged under the evaporator  60 , a process for determining the amount of the frost, determining the frost removing time, and putting the frost removing heater into operation is identical to a case described with reference to  FIGS. 4 and 8A . 
     In the meantime, if a pattern the frost F is formed on the evaporator  60  is examined, the frost F is formed starting from the top toward the bottom of the evaporator, or starting from the bottom toward the top of the evaporator. Though the frost forming pattern can vary with a flow path of the cold air producing chamber and a structure of the evaporator, in most of cases, in general, since the frost F is formed starting from the top toward the bottom of the evaporator, it is preferable that the optical sensor  100  is arranged over the evaporator. 
     Referring to  FIG. 6 , the optical sensor  100  can be arranged such that the evaporator  60  is positioned between the light emitting unit  110  and the light receiving unit  120 . For an example, the light emitting unit  110  is arranged over the evaporator  60 , and the light receiving unit  120  is arranged under the evaporator, or vice versa. Or, the light emitting unit  110  is arranged in front of the evaporator  60 , and the light receiving unit  120  is arranged in rear of the evaporator, or vice versa. 
     Referring to  FIGS. 6 and 8B , if the light directed to the evaporator is reflected at the frost F on the evaporator, since the light can not pass through the evaporator  60  to fail to be received at the light receiving unit  120 , the greater the amount of the frost on the evaporator  60 , the smaller the quantity of light received thus. Therefore, if the quantity of light is smaller than a reference value S 2  as a result of comparison of the quantity of light to the reference value S 2  measured in advance experimentally, the control unit  200  can put the frost removing heater  70  into operation. 
     Referring to  FIG. 7 , in order to enhance reliability of the measurement, it is preferable that a distance d from the optical sensor (the light emitting unit  110  and the light receiving unit  120 ) to the evaporator is fixedly maintained. 
     The refrigerator in accordance with a preferred embodiment of the present invention can include a bracket  130  which connects the optical sensor to the evaporator, additionally. 
     The bracket  130  includes a body  131  which is an extension in a height direction (upward or downward) of the evaporator and has at least one slot  132  for placing the tube  61  therein, and a mounting portion  133  which is an inward bent from an end of the body  131  for mounting the optical sensor toward the evaporator  60  thereto. 
     As described with reference to  FIGS. 4 and 5 , the body  31  has a structure which is applicable to the cases the optical sensor is arranged over or under the evaporator  60 , and can have an angle shaped section, actually. In this structure, as described before, the control unit can operate the frost removal heater in a case the quantity of the light received at the light receiving unit is greater than the reference value. 
     It is preferable that the slot  132  has elasticity, and is detachably mounted to the refrigerant tube  62  for convenience of replacement or service. 
     Different from this, the bracket can include a body which is an extension in a direction of a height of the evaporator with at least one slot for placing the refrigerant tube therein, and a mounting portion which is inward bents from both ends of the body for mounting the optical sensor thereto, respectively. 
     In this instance, the body can have one end with the light emitting unit mounted thereto and the other end with the light receiving unit mounted thereto. 
     And, as described with reference to  FIG. 6 , the body structure can be applicable in a case the evaporator  60  is arranged between the light emitting unit and the light receiving unit of the optical sensor, and the body can have a channel shaped section, actually. In this structure, as described before, the control unit can operate the frost removal heater in a case the quantity of the light received at the light receiving unit is smaller than the reference value. 
       FIG. 9  illustrates a flow chart showing the steps of a method for controlling a refrigerator in accordance with a preferred embodiment of the present invention in a case the optical sensor is arranged at a position shown in  FIG. 6 . 
     Referring to  FIG. 9 , the method for controlling a refrigerator includes the steps of (a) directing a light to an evaporator (S 102 ), (b) receiving the light passed through the evaporator (S 103 ), and performing frost removal with reference to a quantity of the light received thus (S 104  and S 105 ). 
     The steps (a) and (b) can be preformed with the optical sensor  100 , and the step (a) can further include the step (S 101 ) of determining whether a measuring time is reached or not, and, accordingly, since power is applied only when measurement is required, power consumption can be reduced. 
     And, the optical sensor is positioned as described with reference to  FIGS. 4˜6 , and in a case the optical sensor is positioned at a position of  FIGS. 4 and 5 , the light reflected at the evaporator can be received in the step (b), and the frost can be removed in a case the quantity of the reflected light is greater than the reference value. 
     Different from this, if the optical sensor is arranged at a position of  FIG. 6 , the light passed through the evaporator can be received at the step (b), and the frost can be removed in a case the quantity of the passed light is smaller than the reference value. 
     As has been described, the refrigerator and the method for controlling the same of the present invention have the following advantages. 
     The amount of frost on the evaporator can be measured in real time to determine the frost removal time. 
     Power consumption caused by unnecessary frost removal can be reduced, and a number of temperature rise times of the storage space can be reduced. 
     Since the frost removal is performed with reference to a measured actual amount of frost accumulation, reliability of the refrigerator can become high. 
     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 inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.