Patent Publication Number: US-9429352-B2

Title: Air conditioner and method of controlling the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Korean Patent Application No. 10-2012-0020417, filed on Feb. 28, 2012 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an air conditioner and a method of controlling the same, and more particularly, to an air conditioner for detecting freezing inside the air conditioner to protect an outdoor unit and a method of controlling the same. 
     2. Description of the Related Art 
     In general, an air conditioner cools and heats indoor using a refrigerating cycle of a refrigerant formed with a compressor, a condenser, an expanding device, and an evaporator in order to provide more comfortable indoor environment to a user. 
     In an industrial air conditioner or a central air conditioner, a cooler formed with a compressor, a condenser, an expansion device, and an evaporator cools water and conditions indoor air of a large building such as a building, a factory, or a sports center using the cooled water. 
     In such an air conditioner, an outdoor unit is installed outdoors and an operation of the outdoor unit may be influenced by weather or an outdoor temperature. In particular, in a heat exchanger included in an outdoor unit, when the outdoor unit performs a cooling operation or a heating operation, freezing where water generated due to heat exchange is frozen on a surface of a heat exchanger occurs. 
     Freezing occurring on the surface of the heat exchanger deteriorates heat exchange efficiency which results in deterioration of an operation efficiency of the air conditioner. To solve the above problem, an outdoor unit performs a defrosting operation. When the defrosting operation is performed, cooling or heating operation into the indoor is impossible so that a user experiences inconvenience. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in an effort to solve the above problems, and the present invention provides an air conditioner for detecting freezing generated from a heat exchanger inside an outdoor unit and controlling a defrosting operation according to a freezing degree, and a method of controlling the same. 
     According to an aspect of the present invention, there is provided an air conditioner including: a compressor; a heat exchanger performing heat exchange between a refrigerant and air through movement of the air; a frost formation detector provided in the heat exchanger for detecting a frost formation degree in the heat exchanger to output a detection signal; and a controller computing a frost formation level due to freezing in the heat exchanger according to the detection signal inputted from the frost formation detector, and controlling the compressor according to the frost formation level to perform a defrosting operation. 
     According to another aspect of the present invention, there is provided method of controlling an air conditioner, including: receiving a detection signal changed according to contacts between a plurality of electrodes of a frost formation detector installed in a heat exchanger while the air conditioner is operating; computing a frost formation level corresponding to the detection signal; performing a defrosting operation when the frost formation level is equal to or greater than a reference value; and returning to a general operation when the defrosting operation is performed for a predetermined time or when the frost formation level is less than the reference value. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description given herein below and the accompanying drawings, which are given by illustration only, and thus are not limitative of the present invention, and wherein: 
         FIG. 1  is a view illustrating an air conditioner according to an exemplary embodiment of the present invention; 
         FIG. 2  is a block diagram schematically illustrating a control configuration of an outdoor unit of an air conditioner according to an exemplary embodiment of the present invention; 
         FIG. 3  is a view illustrating a heat exchanger of an air conditioner according to an exemplary embodiment of the present invention; 
         FIG. 4  is a view illustrating a configuration of a frost formation detector installed in a heat exchanger; 
         FIG. 5  is a circuit diagram illustrating a configuration of the frost formation detector; and 
         FIG. 6  is a flowchart illustrating a method of detecting frost formation in a heat exchanger and controlling an air conditioner according to an exemplary embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. The present inventive concept may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this description will be thorough and complete, and will fully convey the scope of the present inventive concept to those skilled in the art. The same reference numbers are used throughout the drawings to refer to the same or like parts. Detailed descriptions of well-known functions and structures incorporated herein may be omitted to avoid obscuring the subject matter of the present invention. 
     Hereinafter, an air conditioner and a method of controlling the same according to embodiments of the present inventions will be described with reference to the accompanying drawings. 
       FIG. 1  is a view illustrating an air conditioner according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 1 , an air conditioner includes an outdoor unit  1  and a plurality of indoor units  11  to  16 . 
     The indoor units  11  to  16  may condition indoor air and be simultaneously or independently operated according to an indoor air conditioning load. 
     The air conditioner may include a ventilation unit and an air cleaning unit for mixing fresh outdoor air with internally circulated indoor air. 
     The indoor units  11  to  16  are connected to the outdoor unit  1  through a refrigerant pipe and a communication line, receive a refrigerant, and communicate with the outdoor unit  1 . 
     Each of the indoor units  11  to  16  includes an indoor heat exchanger (not shown), an indoor fan (not shown), and an expansion valve (not shown) in which a supplied refrigerant is expanded, and a plurality of sensors (not shown). 
     The outdoor unit  1  includes a compressor (not shown) receiving a refrigerant and compressing, an outdoor heat exchanger (not shown) heat-exchanging the refrigerant with outdoor air, an accumulator (not shown) extracting gas refrigerant from the supplied refrigerant and providing the extracted gas refrigerant to the compressor, and a 4-way valve (not shown) selecting a flow passage of the refrigerant according to a heating operation. 
     The outdoor units  11  to  16  may further include an outdoor fan (not shown) moving outdoor air to an outdoor heat exchanger (not shown), an outdoor temperature sensor (not shown) detecting an outdoor temperature, and a snowfall detector detecting a snowfall amount outside the outdoor unit  10 . 
     The outdoor unit  10  further includes a plurality of sensors, valves, and oil recovery devices but a description thereof is omitted below. 
       FIG. 2  is a block diagram schematically illustrating a control configuration of an outdoor unit of an air conditioner according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 2 , an outdoor unit of the air conditioner constructed as illustrated includes a compressor  171 , a compressor controller  170 , an outdoor fan  181 , a valve controller  180 , a data part  190 , a communication part  160 , a heat exchanger  120 , a frost formation detector  130 , an output part  140 , a sensor  150 , and a controller  110  controlling an overall operation of the outdoor unit. 
     The input part  145  includes at least one switch and inputs a signal according to operation on/off of the outdoor unit and setting with respect to an operation of the outdoor unit. The input part  120  sets an address or a mode of outdoor unit according to setting of the switch. 
     The output part  140  outputs presence of an operation or a communication state of the outdoor unit and outputs a specific effect sound and an alarm sound in some cases. 
     The sensor  150  includes a plurality of sensors, and is mounted inside or outside the outdoor unit, and measures a temperature and pressure of a refrigerant, and temperatures of respective parts of the outdoor unit and inputs the measured temperatures and the pressure of the refrigerant, and the measured temperatures of respective parts of the outdoor unit  1  to the controller  110 . The sensor  150  detects a flow rate of the refrigerant and inputs the detected flow rate of the refrigerant to the controller  110 . 
     The frost formation detector  130  is installed in the heat exchanger  120 , and detects a frosting degree in the heat exchanger  120 . In this case, the frost formation detector  130  detects freezing in the heat exchanger  120 , namely, presence of formation and a formation degree of frost or ice. 
     The heat exchanger  120  heat-exchanges air moving by an outdoor fan  181  with the refrigerant. In this case, water generated due to a temperature difference is formed and is frozen to the frost or ice in the heat exchanger during a heat exchanging procedure. 
     The frost formation detector  130  detects freezing on a surface of the heat exchanger  120 . 
     The compressor controller  170  controls the compressor  171  to be operated and controls an operation frequency of the compressor  171 . 
     The valve controller  180  controls opening/closing and a degree thereof of a plurality of valves  181 . A fan controller (not shown) controls an outdoor fan  181  to be rotated, and controls rotating speed of the outdoor fan  181  to control movement of air in the heat exchanger  120 . 
     The communication part  160  transceives data with another outdoor unit or an indoor unit, and communicates with a central controller in some cases. 
     The data part  190  accumatively stores data detected or measured by the sensor  150  and the frost formation detector  130 . The data part  190  stores control data for controlling an operation of an outdoor unit and reference data for determining failure. 
     The controller  100  provides a control command to the compressor controller  170  according to input data such that the compressor  171  is operated. The controller  110  operates the outdoor fan  181  and controls movement of a refrigerant through valve control by the valve controller  180 . 
     The controller  100  operates the compressor  171  and the outdoor fan  181 , determines failure of an operation of the outdoor unit  1 , and outputs an operation state to the output part  140  according to input data from the sensor  150 . 
     The controller  110  controls an operation of the outdoor unit  1  according to a frost formation value inputted from the frost formation detector  130 . The controller  110  controls the outdoor unit to perform a defrosting operation according to a degree of frost formation, namely, a freezing degree in the heat exchanger. 
     In this case, the controller  110  converts data inputted from the frost formation detector  130 , compares the converted data with reference data, and determines a degree of frost formation based on the comparison result. If the converted data is equal to or greater than the reference data, the controller  110  provides a control command to the compressor controller  170  such that the outdoor unit performs a defrosting operation. 
     The controller  110  determines a snowfall amount corresponding to a detection signal inputted from the frost formation detector  130 . The controller  100  compares the detection signal of the frost formation detector  130  with reference data stored in the data part  190  and determines a frost formation degree based on the comparison result. The controller  110  may classify magnitude of the detection signal into a plurality of levels and determine a frost formation level as one of the levels. 
     If it is determined that a defrosting operation is required, the controller  110  performs a defrosting operation for a predetermined time and again operates the air conditioner in a designated operation mode, and again performs the defrosting operation according to the detection signal inputted through the frost formation detector  130 . 
     Because normal cooling/heating operations are impossible during a defrosting operation, the controller  110  confirms a time point of a defrosting operation according to a detection signal of the frost formation detector  130  such that an operating time of the defrosting operation or the number of times of defrosting operations is minimized. 
     When the defrosting operation is performed for greater than a predetermined time, the controller  110  returns to a general operation and performs the cooling/heating operations even if a frost formation level is equal to or greater than a predetermined value. 
     In this case, when the number of times of the defrosting operations performed within a period or a predetermined time of the defrosting operation is equal to or greater than a reference value, the controller  110  changes the reference value or a time of the defrosting operation. 
       FIG. 3  is a view illustrating a heat exchanger of an air conditioner according to an exemplary embodiment of the present invention. For example, a following description will be made on the assumption that the heat exchanger has a ‘ ’ shape as illustrated in  FIG. 3  such that heat exchange efficiency is improved by maximizing a contact area with air. 
     As shown, the following description will be made on the assumption that the frost formation detector  130  is longitudinally installed in the center of the heat exchanger  120  by way of example. 
     In general, because freezing in the heat exchanger  120  is formed from a lower end to an upper end according to flow direction of the refrigerant, the frost formation detector  130  is longitudinally installed and detects freezing which is generated from the lower end of the frost formation detector  130  and progresses to the upper end thereof. 
     In this case, the foregoing embodiment has illustrated that the frost formation detector is installed in a central portion of the heat exchanger by way of example. However, the present invention is not limited thereto. That is, it is apparent that the frost formation detector may be installed in a left side or a right side of the heat exchanger  120 . 
       FIG. 4  is a view illustrating a configuration of a frost formation detector installed in a heat exchanger. 
     Referring to  FIG. 4( a ) , a frost formation detector  130  is longitudinally installed in the heat exchanger  120 . In this case, the frost formation detector  130  is configured suited to intervals of copper pipes  122  of the heat exchanger. In some cases, intervals of copper pipes  122  may be changed such that the frost formation detector  130  is mounted in one side of the heat exchanger  120 . 
     In this case, the frost formation detector  130  has a structure which is coupled between fins of the heat exchanger. 
     The frost formation detector  130  include a plurality of electrodes  132  and  133  and insulation parts  134 . 
     The electrodes  132  and  133  protrude from a body  131  of the frost formation detector  130  which is longitudinally in the heat exchanger  120 . 
     In this case, the electrodes  132  and  133  are configured parallel to a copper pipe in a longitudinal direction of the heat exchanger  120 , and are a plurality of layers formed from a lower end of the body  131  to an upper end thereof. 
     The electrodes  132  are respectively provided at a left side and a right side of the body  131 , and the electrode  133  is provided at a central portion of the body  131 , so that three electrodes are configured in one layer. The sizes of respective electrodes and intervals between layers of the respective layers may be changed according to the size of a copper pipe of the heat exchanger  120 . 
     The insulation parts  134  are provided in left and right electrodes in a direction of the copper pipe  122  of the heat exchanger  120 , respectively. 
     As shown in  FIG. 4 b   , insulation parts  134   a  and  134   b  are provided in outer sides of the first and second protruding electrodes  132   a  and  132   b , namely, in a direction of a copper pipe of the heat exchanger  120 . A third electrode  133  is provided at a central portion of a body. 
     The first to third electrodes  132  and  133  are provided parallel to each other. In this case, the first and second electrodes  132  are bent. 
     In this case, in the frost formation detector  130 , the first and second electrodes  132  do not make contact with the copper pipe  122  of the heat exchanger  124  but the insulation part  134  makes contact with the heat exchanger  120 . 
     When frost is generated to generate freezing or water is frozen due to generation of water in the copper pipe  122  of the heat exchanger  120 , the first and second electrodes  132  are bent in a direction of the third electrode  133  of a central portion. 
     If a frozen amount is increased, bending of the first and second electrode  132  is increased so that the first or second electrodes  132  make contact with the third electrode  133 . 
     If the first electrode  132  or the second electrode  132  is connected to the third electrode  133  by making contact with the third electrode  133 , the frost formation detector  130  generates and provides a detection signal of predetermined amplitude to the controller  110 . 
     In this case, the frost formation detector  130  is connected to a resistor of a predetermined size for each layer. Accordingly, because the number of internally connected resistors is different according to coupling of electrodes between layers, different detection signals are provided to the controller  110  according to contact electrodes. 
     The controller  110  classifies a level of the detection signals into a plurality of levels according to amplitudes of the detection signals to determine a frost formation level. The classification of the frost formation level according to the amplitudes of the detection signals may be achieved according to reference data stored in the data part. 
     Accordingly, the following is a circuit arrangement of the frost formation detector  130 . 
       FIG. 5  is a circuit diagram illustrating a configuration of the frost formation detector.  FIGS. 5( a ) and ( b )  are examples of a circuit arrangement of the frost formation detector, and connection and a configuration thereof may be changed. 
     The first to third electrodes act as a switch, and an internal circuit is connected to the first to third electrode so that a detection signal of predetermined magnitude is provided to the controller when the electrodes make contact with each other according to freezing in the heat exchanger. 
     As shown in  FIG. 5( a ) , a plurality of resistors is connected to the first to third electrodes, and electrodes by layers of the frost formation detector  130  separately operate as a switch, respectively. 
     That is, the first to third electrodes are internally connected to resistors and operate as a first switch S 1 , and another electrode provided at lower ends of the first to third electrodes acts as a second switch S 2 . 
     Since a switch configured by a plurality of electrodes is turned-on according to a freezing degree to configure an internal circuit as electrodes make contact with each other from a lower end, and the number of resistors in a path is changed according to a switched location, a value of a detection signal Vout in which a voltage is divided and the divided voltage is outputted is changed. 
     For example, if the third switch S 3  is turned-on, a voltage with respect to a fifth resistor R 5 , and second to fourth resistors R 2 , R 3 , and R 4  is divided and a detection signal Vout is outputted. If the second and third switches S 2  and S 3  are turned-on, the fourth and fifth resistors are connected to each other in parallel so that a voltage divided with respect to the second and third resistors R 2  and R 3  is outputted as the detection signal Vout. 
     As shown in  FIG. 5( b ) , a circuit may be configured in which two switches are provided in one layer in such a way that a first electrode and a third electrode constitutes one switch S 1  and a second electrode and the third electrode constitutes one switch S 4 . 
     One switch is connected so that a detection signal having predetermined magnitude whose voltage is divided is outputted. 
     The controller  110  may determine a frost formation degree, namely, a degree by which freezing occurs in the heat exchanger according to magnitude of a voltage of the detection signal. 
     When a voltage of the detection signal is equal to or greater than a reference value, the controller  110  provides a control signal to a compressor controller  170  such that a defrosting operation is performed. 
     For example, if it is determined that a freezing degree determined according to the detection signal is equal to or greater than ½ of the heat exchanger, the controller  100  may instruct the defrosting operation. 
     The reference value may be changed according to at least one of peripheral environments in which the outdoor unit is provided, an outdoor temperature, an indoor temperature, or a season. 
       FIG. 6  is a flowchart illustrating a method of detecting frost formation in a heat exchanger and controlling an air conditioner according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 6 , an air conditioner detects a freezing degree in a heat exchanger by a frost formation detector  130  during an operation (S 310 ) and receives a detection signal (S 320 ). 
     The controller  110  analyzes the detection signal (S 330 ) and computes a frost formation level indicating the freezing degree (S 340 ). 
     The controller  110  determines whether a defrosting operation is required by comparing the computed frost formation level with a preset reference value (S 350 ). 
     When it is determined that the defrosting operation is required, the controller  110  outputs a message indicating that the defrosting operation is performed through a display part. In this case, an output part may output a message or an effect sound according to the defrosting operation, or a defrosting operation alarm message. In some cases, the outdoor unit transmits the defrosting operation alarm message to the indoor unit through a communication unit so that an alarm with respect to the defrosting operation is outputted through the indoor unit. 
     The controller  100  provides a control command to the compressor controller  170  so that the defrosting operation starts (S 370 ). 
     The controller  110  performs the defrosting operation for a predetermined time, returns to a general operation mode according to setting, and performs cooling/heating operations. 
     The controller  110  may detect frost formation through the frost formation detector  130  during the defrosting operation and determine a frost formation level according to an input detection signal to determine whether to maintain the defrosting operation. 
     In this case, it is preferable that a criterion of determining stop of the defrosting operation is set lower than a frost formation level in a case of starting the defrosting operation. In some cases, when freezing is not solved for a predetermined time, the defrosting operation may stop and then restart a predetermined time later. 
     The controller  110  continuously determines a freezing degree in the heat exchanger through the frost formation detector during an operation to perform a defrosting operation. 
     Accordingly, the air conditioner detects a degree of freezing occurring in the heat exchanger of an outdoor unit to perform a defrosting operation, thereby preventing heat exchange efficiency due to freezing in the heat exchanger from being deteriorated. Further, a defrosting operation is more efficiently performed so that more comfortable indoor environment may be provided while performing the defrosting operation. 
     The air conditioner and the method of controlling the same according to the present invention detect freezing occurring in the heat exchanger of the outdoor unit, determine a time of the defrosting operation according to a freezing degree such that the defrosting operation is performed, thereby preventing cooling/heating operation efficiency and capability due to a frequent defrosting operation from being deteriorated. The air conditioner and the method of controlling the same according to the present invention provide comfort of a predetermined level to the user to solve deterioration of convenience, and remove freezing due to a defrosting operation to thereby improve efficiency during cooling/heating operations. 
     The embodiment of the invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.