JP6454210B2 - refrigerator - Google Patents

Description

  The present invention relates to a refrigerator for storing articles at a low temperature.

  The refrigerator includes a storage room (freezer room, refrigeration room, etc.) that is formed in a heat-insulating space surrounded by a housing and a door and stores food and the like at a low temperature, and a cooling device that cools the inside of the storage room. . In a cooling device used in a general refrigerator, an evaporator is connected to a compressor that operates a refrigeration cycle. Cold air generated by heat exchange with the evaporator is sent into the storage chamber by driving a blower fan, and the storage chamber is cooled.

  In the evaporator, moisture contained in the air condenses, freezes and adheres as frost (frosts). When the frost adheres to the evaporator, a region through which air passes is narrowed and heat exchange efficiency is lowered, that is, the cooling capacity of the refrigerator is lowered.

  Therefore, in the refrigerator, in order to remove frost adhering to the evaporator, the operation of the refrigerator is stopped and a defrosting heater disposed in the vicinity of the evaporator is driven to melt the frost. Defrosting operation to remove. In a conventional refrigerator, a compressor with a constant output is often used, and in such a compressor, there is a correlation between the operation time of the compressor and the amount of frost formation, based on the drive time of the compressor. Defrost control for defrosting is performed.

  In addition, in order to suppress the temperature rise of the storage room by appropriately setting the defrosting timing, the number of times of opening and closing the door of the refrigerator is confirmed, and there is also a type that performs defrosting in a time zone where the door opening and closing frequency is low. (Patent Document 1).

  Also, there are those that control the defrosting based on the time obtained by counting the time when the door was open and adding the time obtained by converting the accumulated time to the operating time of the compressor to the actual driving time of the compressor Yes (Non-Patent Document 1).

JP-A-5-79749

GE Consumer Home Service Training: “Technical Service Guide Adaptive Defrost”

  In recent years, an inverter-controlled compressor has been increasingly used in a refrigeration apparatus. Since the compressor is operated while adjusting its output, the operating rate is higher than that of a constant-output compressor. For this reason, when an inverter-controlled compressor is used, the frequency of defrosting increases when defrosting is performed with the integrated value of the operating time of the compressor.

  In addition, in a refrigeration system using an inverter-controlled compressor, the output of the compressor is fluctuated, so the integrated value of the operating time of the compressor and the amount of frost formation on the evaporator are unlikely to be proportional to each other. When the defrost control is performed with the integrated value of the operating time of the machine, the defrost is frequently performed even though the amount of frost formation is small, which may lead to waste of electric power.

  Furthermore, refrigerators (Patent Document 1, Non-Patent Document 1, etc.) that perform the defrosting control of the evaporator in consideration of the integrated value of the door opening / closing frequency or the opening time in addition to the movable time of the compressor are also available. However, it is difficult to add the influence of a storage room having a temperature difference, and it may be difficult to optimize the timing of defrosting.

  Then, an object of this invention is to provide the refrigerator which can perform the defrost operation which removes the frost formation of an evaporator efficiently, and can reduce power consumption.

  To achieve the above object, the present invention provides a compressor for operating a refrigeration cycle, an evaporator connected to the compressor to cool the first storage chamber, and cooled by the evaporator from the first storage chamber. A second storage chamber that is maintained at a high temperature, a damper that opens and closes a cold air passage between the evaporator and the second storage chamber, and a defrosting unit that performs a defrosting operation to melt frost attached to the evaporator And acquiring information on at least opening / closing of the door of the first storage chamber, opening / closing of the damper and driving time of the compressor, and calculating an expected frost formation amount of the evaporator based on these information There is provided a refrigerator including a control unit that issues an instruction to perform the defrosting operation to the defrosting unit when a frosting amount exceeds a threshold value.

  According to this configuration, since the frost formation amount of the evaporator is calculated from information on the opening / closing of the door of the first storage chamber, the opening / closing of the damper and the driving time of the compressor, the frost formation amount can be accurately determined with a simple configuration. I can grasp it. And the amount of frost formation can be grasped correctly. Furthermore, since it is the structure which performs a defrost operation based on the calculated amount of frost formation, the timing of a defrost operation can be optimized easily and the increase in power consumption can be suppressed.

  In the above configuration, the control unit is configured to continuously open and close the door of the first storage chamber, the cumulative opening time of the door of the first storage chamber, the cumulative driving time of the compressor, and the damper continuously for a predetermined time or more. Then, the number of times of opening may be detected, and the expected frost amount may be calculated based on the respective values.

  In the above configuration, the control unit compares a predetermined defrosting time determined in advance with an actual defrosting time required for defrosting during the defrosting operation, and a difference between the assumed defrosting time and the actual defrosting time is determined in advance. When the predetermined range is exceeded, the threshold value may be changed. By comprising in this way, the shift | offset | difference of the estimated frost amount and the actual frost amount by calculation of the said control part can be correct | amended, the timing of a defrost operation can be optimized easily, and power consumption is reduced. Increase can be suppressed.

  In the above configuration, when the actual defrost time is longer than the assumed defrost time, the control unit changes the threshold value to a smaller value, and when the actual defrost time is shorter than the assumed defrost time, The threshold value may be changed to a large value. By comprising in this way, the shift | offset | difference of the estimated frost amount and the actual frost amount by calculation of the said control part can be correct | amended, the timing of a defrost operation can be optimized easily, and power consumption is reduced. Increase can be suppressed.

  In the above-described configuration, a dew condensation prevention heater for preventing dew condensation on the outer surface is provided in a portion adjacent to the outer surface of at least one of the first storage chamber or the second storage chamber, and the controller is configured to exclude the assumption. The output of the dew condensation heater may be adjusted when the difference between the frost time and the actual defrost time exceeds a predetermined range. By comprising in this way, since a dew condensation prevention heater is operated when dew condensation is anticipated on the surface of a refrigerator, the useless drive of a dew condensation prevention heater can be suppressed and the increase in power consumption can be suppressed.

  In the above configuration, when the actual defrost time is equal to or longer than the estimated defrost time, the control unit increases the output of the dew condensation prevention heater. When the actual defrost time is less than the estimated defrost time, The output of the prevention heater may be lowered. By comprising in this way, since the said dew condensation prevention heater can be driven without excess and deficiency, while suppressing the dew condensation on the refrigerator surface reliably, the increase in power consumption can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the defrost operation which removes the frost formation of an evaporator can be performed efficiently, and the refrigerator which can reduce power consumption can be provided.

It is side surface sectional drawing of an example of the refrigerator concerning this invention. It is a block diagram which shows the structure of the refrigerator shown in FIG. It is a flowchart which shows the defrost operation of the refrigerator concerning this invention. It is a flowchart which shows the detection of a 1st parameter and a 2nd parameter. It is a flowchart which shows the detection of a 3rd parameter. It is a flowchart which shows the detection of a 4th parameter. It is a figure which shows the temperature of the evaporator at the time of a defrost operation. It is a flowchart of the defrost operation of the refrigerator concerning this invention. It is a sectional side view of the other example of the refrigerator concerning this invention. It is a block diagram which shows the structure of the refrigerator shown in FIG. It is a flowchart which shows the dew condensation prevention operation | movement of the refrigerator concerning this invention.

<First Embodiment>
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view of an example of a refrigerator according to the present invention. The refrigerator A has a heat insulating box 1 filled with a foam heat insulating material. A refrigerator compartment 3 is provided at the top of the heat insulating box 1. A freezer compartment 4 is provided below the refrigerator compartment 3 via a partition wall 101 filled with a heat insulating material. Below the freezer compartment 4, a vegetable compartment 5 is provided via a partition wall 102 filled with a heat insulating material. The refrigerator room, freezer room, and vegetable room are not necessarily in this order, and may be changed according to the frequency of use, the amount of stored items, and the like. Moreover, you may provide the store room which stores a store thing at temperature other than these store rooms.

  The freezer compartment 4 stores the stored product in a frozen state. The refrigerator compartment 3 refrigerates and stores stored items at a higher temperature than the freezer compartment 4, and the vegetable compartment 5 maintains a temperature higher than that of the refrigerator compartment 3 to refrigerate and preserve stored items such as vegetables. In addition, the freezer compartment 4 is a 1st store room, and the refrigerator compartment 3 and the vegetable compartment 5 are a 2nd store room.

  The refrigerator compartment 3 is opened and closed by a pair of double doors 31 pivoted at the left and right ends. The freezer compartment 4 and the vegetable compartment 5 are opened and closed by drawer type doors 41 and 51 formed integrally with a storage case (not shown), respectively.

  A cold air passage 7 and a cold air passage 8 communicating with each other via a damper 15 are provided on the back surfaces of the freezer compartment 4 and the refrigerator compartment 3. A cold room fan 13 and a cold room fan 14 for circulating cold air are arranged in the cold air passage 7 and the cold air flow path 8, respectively. Below the freezer compartment fan 13, an evaporator 12 for generating cold air is disposed. A defrost heater 16 for removing (defrosting) frost attached to the evaporator 12 is disposed below the evaporator 12. The upper surface of the defrost heater 16 is covered with a heater cover 161. The heater cover 161 suppresses failure, breakage, and the like of the defrost heater 16 caused by the defrost water dripping onto the defrost heater 16.

  The cold air passage 7 is provided on the back surface of the freezer compartment 4, and a part of the lower portion is provided on the back surface of the vegetable compartment 5. The cool air passage 7 includes a discharge port 71 that is an opening for discharging cool air to the freezer compartment 4, and a return port 72 that is an opening for returning the cool air from the freezer chamber 4 to the cool air passage 7. The cool air flow path 8 is provided on the back surface of the refrigerating chamber 3 and includes a discharge port 81 that is an opening for discharging cool air. The heat insulation box 1 is provided with a communication path (not shown) that allows the refrigerator compartment 3 and the vegetable compartment 5 to communicate with each other. The cold air passage 7 is provided with a return port 73 that opens into the vegetable compartment 5 and from which the cold air returns from the vegetable compartment 5 to the cold air passage 7.

  A machine room 6 is provided below the cold air passage 7 on the back of the vegetable room 5, and a compressor 11 for operating a refrigeration cycle is installed inside the machine room 6. The refrigerant flows through a refrigerant pipe (not shown) by driving the compressor 11, and the evaporator 12 connected to the compressor 11 through the refrigerant pipe is maintained at a low temperature. In the evaporator 12, flat fins (not shown) are arranged, and refrigerant fins pass through the fins. And heat exchange with a refrigerant | coolant and air is performed by flowing air through the clearance gap between several fins. In addition, the contact area of air and the evaporator 12 is increased by providing a some fin, and the efficiency of heat exchange is improved.

  When the freezer compartment fan 13 is driven, the cold air heat-exchanged with the evaporator 12 flows through the cold air passage 7. When the damper 15 is closed, the cold air flowing through the cold air passage 7 is discharged from the discharge port 71 into the freezer compartment 4. The cold air discharged from the discharge port 71 flows through the inside of the freezer compartment 4, cools the stored items in the freezer compartment 4, and returns to the cold air passage 7 from the return port 72. That is, the cold air in the cold air passage 7 circulates in the freezer compartment 4, cools the internal storage (receives heat from the storage and is heated), and returns to the cold air passage 7.

  When the damper 15 is open, the cold air flowing through the cold air passage 7 flows into the cold air flow path 8. By driving the freezer compartment fan 13 and the freezer compartment fan 14 with the damper 15 open, the cold air circulating in the freezer compartment 4 and the cold air passage 8 is refrigerated from the discharge port 81 as described above. It is discharged into the chamber 3. And the cool air discharged from the discharge port 81 flows through the inside of the refrigerator compartment 3, and the stored thing in the refrigerator compartment 3 is cooled. And the cold air | flow which flowed in the refrigerator compartment 3 flows in into the vegetable compartment 5 by the unillustrated communication path, flows through the inside of the vegetable compartment 5, cools the store in the vegetable compartment 5, and then returns to the return port 73. Return to the cold air passage 7.

  The cold air is heated to take heat away from the stored items when flowing in the refrigerator compartment 3. Then, since the heated cold air flows into the vegetable compartment 5, the vegetable compartment 5 is maintained at a higher temperature than the refrigerator compartment 3.

  Next, the electrical configuration of the refrigerator A will be described. FIG. 2 is a block diagram showing the configuration of the refrigerator shown in FIG. As shown in FIG. 2, the refrigerator A includes a control unit 2 that controls the operation of each unit. The control unit 2 includes a compressor 11, a freezer compartment fan 13, a refrigerator compartment fan 14, a damper 15, a defrost heater 16, a freezer compartment temperature sensor 21, a refrigerator compartment temperature sensor 22, an evaporator temperature sensor 23, an operation unit 24, and A freezer compartment door open detection sensor 25 is connected. The control unit 2 includes a timer unit 201 and a storage unit 202.

  The compressor 11, the freezer compartment fan 13, the refrigerator compartment fan 14, the damper 15, and the defrost heater 16 are operated by an output signal from the control unit 2. Moreover, the freezer compartment temperature sensor 21, the refrigerator compartment temperature sensor 22, the evaporator temperature sensor 23, the operation unit 24, and the freezer compartment door opening detection sensor 25 input signals to the control unit 2.

  The freezer temperature sensor 21 detects the temperature inside the refrigerator compartment 4 and sends the temperature information to the controller 2. The refrigerator compartment temperature sensor 22 detects the temperature inside the refrigerator compartment 3 and sends the temperature information to the controller 2. The evaporator temperature sensor 23 is disposed in contact with or close to the evaporator 12, detects the temperature of the evaporator 12, and sends the temperature information to the control unit 2. In addition, the freezer compartment temperature sensor 21, the refrigerator compartment temperature sensor 22, and the evaporator temperature sensor 23 are sensors which detect temperature, For example, what uses a thermistor can be mentioned, but it is not limited to this.

  The rotation speed of the compressor 11 is variably controlled by the control unit 2 (for example, inverter control). And done. The operation unit 24 is provided on the door 31 of the refrigerating room 3 and performs temperature setting for the refrigerating room 3, the freezing room 4, and the vegetable room 5. The operation unit 24 may have a configuration in which the temperature can be set stepwise by a notch or the like, or may be configured to be operated by a plurality of switches. The operation unit 24 may include a display unit that displays the current state of the refrigerator A (for example, the current temperature and temperature setting), and may be configured to perform operation input using a touch panel using a touch sensor.

  The freezer compartment door open detection sensor 25 is a non-contact type or contact type sensor, and is a detector that detects opening and closing of the freezer compartment door 41. In the refrigerator A, when the freezer compartment door detection sensor 25 detects that the freezer compartment door 41 is open, it sends the information to the controller 2.

  The time measuring unit 201 includes information on the current time, and can measure an elapsed time from an arbitrary time point. The storage unit 202 is a memory that stores information such as information sent to the control unit 2, information processed by the control unit 2, and information previously given to the control unit 2. Note that the timing unit 201 and the storage unit 202 are formed integrally with the control unit 2, but are not limited to this, and are provided independently of the control unit 2 and can be freely accessed by the control unit 2. It may be a configuration.

  Next, the operation of the refrigerator A will be described. In general, the refrigerator compartment 3 and the freezer compartment 4 have appropriate temperature ranges for cooling the stored items. In the refrigerator A, as the set temperatures inside the refrigerator compartment 3 and the freezer compartment 4, three types of cooling settings of low temperature “strong”, high temperature “weak”, and intermediate “medium” are set in advance in an appropriate temperature range. I have prepared it. Any one of the three types of cooling settings can be selected by the user using the operation unit 24, and the control unit 2 cools the refrigerator compartment 3 and the freezer compartment 4 based on the selected cooling settings. To do.

  The control unit 2 controls the operations of the compressor 11, the freezer compartment fan 13, the refrigerating compartment fan 14, and the damper 15 so that the temperatures inside the refrigerating compartment 3 and the freezer compartment 4 become the selected set temperature. . The cooling setting is not limited to these three types, and may be determined more finely. Moreover, you may be able to change freely the set temperature of the refrigerator compartment 3 and / or the freezer compartment 4 in the range which does not exceed an appropriate temperature range.

  More specifically, the control unit 2 stores the set temperatures of the refrigerator compartment 3 and / or the freezer compartment 4 based on the input from the operation unit 24. The control unit 2 acquires the temperature inside the freezer compartment 4 detected by the freezer temperature sensor 21. When the temperature inside the freezer compartment 4 exceeds the upper limit of the set temperature, the compressor 11 and the freezer compartment fan 13 are obtained. Drive. As a result, the evaporator 12 has a low temperature, and the cold air heat-exchanged with the evaporator 12 is discharged from the discharge port 71 of the cold passage 7 to the freezer compartment 4 to cool the stored items in the freezer chamber 4 and return from the return port 72. It circulates to. And if the control part 2 confirms that the freezer compartment 4 was cooled to predetermined temperature based on the temperature information from the freezer compartment temperature sensor 21, the compressor 11 and the freezer compartment fan 13 will be stopped.

  Further, the control unit 2 acquires the temperature inside the refrigerator compartment 3 from the refrigerator compartment temperature sensor 22, and when the temperature inside the refrigerator compartment 3 exceeds the upper limit of the set temperature, the damper 15 is opened and the compressor 11 and The refrigerator compartment fan 14 is driven. Thereby, the cold air exchanged with the evaporator 12 is sent to the cold air flow path 8 and discharged from the discharge port 81 to the refrigerator compartment 3. And if the control part 2 confirms that the refrigerator compartment 3 was cooled to predetermined temperature based on the temperature information from the refrigerator compartment temperature sensor 22, the damper 15 will be closed, and the compressor 11 and refrigerator compartment fan will be closed. 14 is stopped.

  In the refrigerator A, when the refrigerator compartment 3 is cooled, the refrigerator compartment fan 13 is simultaneously driven in addition to the refrigerator compartment fan 14. Therefore, when the damper 15 is open, the freezer compartment fan 13 and the refrigerator compartment fan 14 are rotating, and a part of the cool air is discharged from the discharge port 71 to the freezer compartment 4 and the rest is discharged from the cool air passage 8. It is discharged from the part 81 to the refrigerator compartment 3.

  In addition, when the damper 15 is open, only the refrigerator compartment fan 14 may be rotated, or the temperature information from the freezer compartment temperature sensor 21 and the temperature information from the refrigerator compartment temperature sensor 22 are taken into consideration. You may make it determine whether to drive only the refrigerator compartment fan 14 or the freezer compartment fan 13 simultaneously. Further, based on the temperature of the refrigerator compartment 3 and the temperature of the freezer compartment 4, the rotational speeds of the freezer compartment fan 13 and the refrigerator compartment fan 14 may be controlled in order to adjust the flow rate of the cold air.

  Furthermore, the compressor 11 is drive-controlled so that the number of revolutions can be changed. In the refrigeration cycle operated by the compressor 11, the refrigeration capacity increases when the number of revolutions of the compressor 11 is high. The control unit 2 controls the rotational speed of the compressor 11 based on temperature information from the freezer temperature sensor 21 and / or the refrigerator temperature sensor 22.

  As described above, when the control unit 2 drives the compressor 11, at least one of the freezer compartment fan 13 and the refrigerator compartment fan 14 is simultaneously driven. When the damper 15 is in the open state, at least the refrigerator compartment fan 14 is driven.

  The control unit 2 controls the driving of the compressor 11, the freezer compartment fan 13, the refrigerating compartment fan 14, and the damper 15 based on the temperatures of the refrigerating compartment 3 and the freezer compartment 4, but is not limited thereto. For example, a sensor for detecting the temperature of the vegetable compartment 5 is provided, and the compressor 11, the freezer compartment fan 13, the refrigerator compartment fan 14, and the damper 15 are driven based on the temperature of the vegetable compartment 5 in addition to the refrigerator compartment 3 and the freezer compartment 4. May be controlled.

  In the refrigerator A as described above, a single evaporator 12 cools the refrigerator compartment 3, the freezer compartment 4, and the vegetable compartment 5 (stored items therein). When the damper 15 is open, the cold air passes through the high temperature refrigerator compartment 3 and the vegetable compartment 5 with respect to the freezer compartment 4 and returns to the evaporator 12. When the stored product is cooled, the temperature of the cold air rises, so that the amount of saturated water vapor increases, and the amount of water vapor contained in the cold air may increase.

  When the cool air with the increased water vapor content contacts the evaporator 12 and the temperature decreases due to heat exchange with the refrigerant, it condenses on the evaporator 12 and adheres (frosts) to the evaporator 12 as frost. If the evaporator 12 has frost formation, the gaps through which air flows may be blocked, resulting in poor cooling efficiency. Therefore, in the refrigerator A, when the evaporator 12 has frost formation, the defrosting operation is performed in which the defrost heater 16 is driven to melt the frost attached to the evaporator 12.

  In the defrosting operation, the compressor 11 is stopped and the evaporator 12 is heated by the defrosting heater 16. During the defrosting operation, the refrigerator room 3, the freezer room 4, and the vegetable room 5 are cooled. Stop. Therefore, when the defrosting operation is frequently performed in the refrigerator A, cooling may not be performed firmly. In addition, since the defrosting heater 16 is driven, power consumption increases when the defrosting operation is performed. Therefore, it is preferable that the number of defrosting operations is small.

  From the above, the temperature of the refrigerator compartment 3, the freezer compartment 4, and the vegetable compartment 5 is suppressed and the power consumption is reduced. That is, as an efficient defrosting operation, the evaporator 12 begins to clog due to frost formation. The defrosting operation can be performed. Therefore, in the refrigerator A, defrosting is performed at the timing when the clogging of the evaporator 12 starts due to frost formation.

  Even if the frosting amount of the evaporator 12 is large, the defrosting operation may not be started if there is a problem with the sensor or the like. Based on such a case, in the refrigerator A, control for determining an abnormality is performed based on the defrosting interval, the temperature of the evaporator 12, and the continuous opening time of the damper 15. And the prediction of the amount of frost formation of the evaporator 12 is also performed simultaneously, and the defrosting based on the estimated amount of frost formation is also performed. The defrosting operation according to the present invention will be described below with reference to the drawings. FIG. 3 is a flowchart showing the defrosting operation of the refrigerator according to the present invention.

  The control unit 2 checks whether or not the elapsed time from the end of the previous defrosting is equal to or longer than a predetermined time T1 (step S101). As a method for detecting the elapsed time, for example, the previous defrosting end time is stored in the storage unit 202 and obtained by the difference from the current time acquired from the time measuring unit 201, but is not limited thereto. A timer may be operated exclusively for the elapsed time.

  When the time since the last defrosting is time T1 or more (in the case of Yes in step S101), the control unit 2 determines that some abnormality (for example, malfunction of the evaporator temperature sensor 23) has occurred, A defrosting operation is started (step S105).

  When the time since the last defrosting is less than T1 (No in step S101), the temperature of the evaporator 12 is acquired from the evaporator temperature sensor 23, and the temperature of the evaporator 12 is equal to or lower than the specified temperature D1. Confirm (step S102). When the temperature of the evaporator 12 is equal to or lower than the specified temperature D1 (Yes in Step S102), the control unit 2 checks whether the continuous opening time of the damper 15 is equal to or longer than a predetermined time T2 (Step S103). If the continuous opening time of the damper 15 is equal to or longer than the time T2 (Yes in step S103), it means that the temperature of the refrigerating chamber 3 has not decreased despite the cooling being performed, and the controller 2 evaporates. The defrosting operation is started by determining that the amount of cold air generated has decreased due to the frost formation of the vessel 12 (step S105).

  When the temperature of the evaporator 12 is higher than the specified temperature D1 (No in step S102), or when the continuous open time of the damper is less than time T2 (in the case of No in step S103), the control unit 2 is the refrigerator A. It is judged that there is no abnormality in driving. The control unit 2 acquires information acquired during operation after the end of the defrosting operation (for example, opening and closing of the freezer compartment door 41 after the end of the previous defrosting operation, the cumulative driving time of the compressor 11, and the state of continuous opening of the damper 15). The frost formation amount of the evaporator 12 is calculated from the number of times of the above. Then, in the case of No in step S102 or No in step S103, the control unit 2 confirms whether or not the calculated frost formation amount (predicted frost formation amount) is greater than or equal to a predetermined frost formation threshold (step S104). .

  As the frost formation threshold, the amount of frost that the evaporator 12 starts to clog can be mentioned. By setting the amount of frost that starts to clog the evaporator 12 as the frost formation threshold, the timing of the defrosting operation can be optimized (the defrosting operation can be performed without excess or deficiency). The amount of frost that starts to clog the evaporator 12 may be obtained by calculation (for example, numerical simulation) from the size or shape of the evaporator 12, or may be obtained by actually operating the refrigerator A. .

  When the expected frost amount is equal to or greater than the threshold value of the frost amount (Yes in step S104), the control unit 2 determines that the evaporator 12 is clogged due to frost formation, and performs the defrosting operation. Start (step S105). Further, when the expected frost amount is less than the frost amount threshold (No in step S104), the control unit 2 determines that the evaporator 12 is not clogged due to frost formation, and from the end of defrosting. The process returns to the confirmation of the elapsed time (step S101).

  And after complete | finishing a defrost driving | operation (step S106), the control part 2 resets a timer, a counter, and a parameter (step S107), and returns to confirmation of the elapsed time from the completion | finish of defrosting (step S101). In addition, a timer, a counter, and a parameter are a timer, a counter, and a parameter used when calculating the expected frost formation amount mentioned later. That is, the control unit 2 newly calculates the frost formation amount of the evaporator 12 every time defrosting is completed.

  In the refrigerator A, defrosting is performed when the frosting amount of the evaporator 12 reaches a certain amount and defrosting is required. Therefore, it is possible to suppress power consumption by suppressing the clogging of the evaporator 12 due to frost formation and suppressing the number of defrosting.

  When performing the defrosting operation shown above, the control unit 2 calculates the frosting amount of the evaporator 12 based on information acquired during the operation of the refrigerator A. Next, the detail of the calculation method of the amount of frost formation is demonstrated.

  When the freezer compartment door 41 is opened, the temperature of the articles inside the freezer compartment 4 may increase, and the relative humidity may increase. And if the frequency | count of opening / closing of the freezer compartment door 41 increases, the temperature inside the freezer compartment 4 will rise. When cold air is circulated in the freezer compartment 4 in this state, the air in the freezer compartment 4 flows into the evaporator 12 and frost tends to adhere to the evaporator 12. From this, it is considered that the opening / closing frequency of the freezer compartment door 41 has an influence on the frost formation of the evaporator 12. Therefore, the open / close count of the freezer compartment door 41 is set as a parameter (first parameter Pm1) for calculating the amount of frost formation in the evaporator 12.

  When the freezer compartment door 41 is left open (open state), a large amount of warm air outside (compared to the inside of the freezer compartment 4) flows into the freezer compartment 4 into the freezer compartment 4. Such warm air also contains more water vapor. Therefore, it is considered that the accumulated opening time of the freezer compartment door 41 has an influence on the frost formation of the evaporator 12, and the accumulated opening time of the freezer compartment door 41 is a parameter for calculating the frost formation amount of the evaporator 12 (second parameter). Pm2).

  The detection of the first parameter Pm1 and the second parameter Pm2 will be described in detail. FIG. 4 is a flowchart showing detection of the first parameter and the second parameter. The control unit 2 confirms whether or not the freezer compartment door 41 has been opened based on information from the freezer compartment door open detection sensor 25 (step S201). If the opening of the freezer compartment door 41 is not detected (No in step S201), the process waits until the opening of the freezer compartment door 41 is detected.

  When the freezer compartment door 41 is opened (Yes in step S201), the control unit 2 calls the first parameter Pm1 from the storage unit 202 and adds 1 to the first parameter Pm1 (opens the freezer compartment door 41). The number of times is added) (step S202).

  Then, the control part 2 confirms whether the freezer compartment door 41 was closed (step S203). When the freezer compartment door 41 is not closed (No in step S203), it waits until the freezer compartment door 41 is closed. When the freezer compartment door 41 is closed (Yes in step S203), a time t1 from when the freezer compartment door 41 is opened until it is closed is detected (step S204). The control unit 2 calls the second parameter Pm2, and adds the time t1 to the parameter Pm2 (step S205). The second parameter Pm2 is acquired in units of minutes, and the time t1 is rounded down to less than 1 minute.

  The control unit 2 stores the first parameter Pm1 and the second parameter Pm2 in the storage unit 202 (step S206). In this way, the control unit 2 acquires the first parameter Pm1 that is the number of times the freezer door 41 is opened and closed and the second parameter Pm2 that is the cumulative open time (minutes). The control unit 2 stores the first parameter Pm1 and the second parameter Pm2 in the storage unit 202 and updates each time it confirms the opening / closing of the freezer compartment door 41. The control unit 2 resets the first parameter Pm1 and the second parameter Pm2 when the defrosting operation is started.

  In the refrigerator A, only when the compressor 11 is driven, the evaporator 12 has a low temperature and cold air flows through the evaporator 12. From this, it can be seen that the operation of the compressor 11 and the frost formation amount of the evaporator 12 are related. Therefore, the cumulative drive time of the evaporator 12 is used as a parameter for calculating the amount of frost formation of the evaporator 12 (third parameter Pm3).

  The detection of the third parameter Pm3 will be described in detail. FIG. 5 is a flowchart showing detection of the third parameter. The controller 2 controls the driving of the compressor 11 based on temperature information from the freezer temperature sensor 21 and the refrigerator temperature sensor 22. Therefore, the control unit 2 stands by until the compressor 11 starts to be driven (step S301). When the compressor 11 is started to be driven (Yes in step S301), the control unit 2 obtains the drive start time from the time measuring unit 201 and waits until the compressor 11 stops (step S302).

  When the compressor 11 is stopped (Yes in step S302), the control unit 2 detects a time t2 from the start of driving of the compressor 11 to the stop (step S303). The time t2 is calculated from the drive start time and the stop time. The control unit 2 calls the third parameter Pm3 from the storage unit 202, and adds the time t2 to the third parameter Pm3 (step S304). The control unit 2 stores the third parameter Pm3 in the storage unit 202 (step S305). Note that the third parameter Pm3 is acquired in time units, and the time t2 is rounded down to less than 1 hour.

  In this way, the control unit 2 acquires the third parameter Pm3 that is the cumulative driving time (time) of the compressor 11. The control unit 2 stores the third parameter Pm3 in the storage unit 202 and updates it every time the driving of the compressor 11 is confirmed. The control unit 2 resets the third parameter Pm3 when the defrosting operation is started.

  In the refrigerator A, the refrigerator compartment 3, the freezer compartment 4, and the vegetable compartment 5 are cooled by using one evaporator 12. The refrigerator compartment 3 is maintained at a temperature that suppresses the propagation of germs, for example, about 5 ° C. without freezing the stored product. The vegetable room 5 is maintained at a temperature slightly higher than the storage room 3, for example, about 5 ° C to 7 ° C. And in the inside of the refrigerator compartment 3 and / or the vegetable compartment 5, water vapor | steam is discharge | released from the stored material and the amount of water vapor | steam contained may increase.

  The air returning from the vegetable compartment 5 to the cool air passage 7 through the return port 73 is about 5 ° C. to 7 ° C., and forms frost on the evaporator 12 when it comes into contact with the evaporator 12 at around −20 ° C. That is, the evaporator 12 is frosted by the circulation of cold air in the refrigerator compartment 3 and the vegetable compartment 5. The cool air is discharged from the discharge port 81 of the cool air flow path 8 to the refrigerator compartment 3, and the flow of the cool air from the cool air passage 7 to the cool air flow path 8 is adjusted by the damper 15.

  And the control part 2 is operating the opening / closing of the damper 15 based on the temperature inside the refrigerator compartment 3, and when the damper 15 is opened, it is a case where the temperature of the refrigerator compartment 3 is rising. And if the opening time of the damper 15 becomes long, the amount of the air in the refrigerator compartment 3 (the air that is higher than the temperature of the evaporator 12 and has a large amount of water vapor) flows into the cold air passage 7 increases. The amount of frost formation also increases.

  Therefore, the number of times that the damper 15 is continuously opened for a predetermined time T3 or more is set as a parameter for calculating the frost formation amount of the evaporator 12 (fourth parameter Pm4). When the continuous opening time t3 of the damper 15 is equal to or longer than the time T3, a value c4 obtained by dividing the continuous opening time t3 by the specified time T3 and rounded down after the decimal point is defined as the number of times. For example, assuming that the specified time T3 is 60 minutes and the continuous opening time t3 of the damper 15 is 130 minutes, the number of times c4 continuously opened is “2”. The opening / closing of the damper 15 is controlled by the temperature inside the refrigerator compartment 3, and the temperature of the refrigerator compartment 3 is strongly influenced by the opening / closing of the refrigerator compartment door 31. Therefore, by setting the number of times that the damper 15 is continuously opened for a predetermined time T3 or more as a fourth parameter, the influence of the opening / closing of the refrigerator compartment door 31 on the frost formation amount of the evaporator 12 is added. be able to.

  The detection of the fourth parameter Pm4 will be described in detail. FIG. 6 is a flowchart showing detection of the fourth parameter. The controller 2 controls the drive of the damper 15 based on the temperature information from the freezer temperature sensor 21. Therefore, the control unit 2 waits until the damper 15 is in an open state (step S401). When the damper 15 is in the open state (when it is Yes in step S401), the control unit 2 acquires the time when the damper 15 is in the open state from the time measuring unit 201, and the damper 15 is in the closed state. (Step S402).

  When the damper 15 is closed (Yes in Step S402), the control unit 2 detects a continuous open time t3 from when the damper 15 is opened to when the damper 15 is closed (Step S403). . The continuous open time t3 is calculated from the time when the open state is reached and the time when the closed state is reached.

  The control unit 2 confirms whether the detected continuous opening time t3 is longer than the specified time T3 (step S404). If the continuous opening time t3 is less than the specified time T3 (No in step S404), the control unit 2 returns to confirming the opening of the damper 15 (step S401). When the detected continuous opening time t3 is longer than the specified time T3 (Yes in step S404), the control unit 2 calculates a value c4 obtained by rounding down the decimal point of the value obtained by dividing the continuous opening time t3 by the specified time T3. (Step S405). The control unit 2 calls the fourth parameter Pm4 from the storage unit 202, and adds the value c4 to the fourth parameter Pm4 (step S406). The control unit 2 stores the fourth parameter Pm4 in the storage unit 202 (step S407).

  In this way, the control unit 2 acquires the fourth parameter Pm4, which is the number of times that the damper 15 has been continuously opened for a specified time or longer. The control unit 2 stores the fourth parameter Pm4 in the storage unit 202 and updates it every time the driving of the compressor 11 is confirmed. The control unit 2 resets the fourth parameter Pm4 when the defrosting operation is started.

  During operation, the control unit 2 of the refrigerator A detects the first parameter Pm1, the second parameter Pm2, the third parameter Pm3, and the fourth parameter Pm4 described above. And the control part 2 calculates the amount of frost formation of the evaporator 12 using these parameters.

The control unit 2 multiplies coefficients corresponding to the first parameter Pm1 to the fourth parameter Pm4, and adds the multiplication results to calculate the frost formation amount of the evaporator 12. That is, assuming that the first coefficient K1, the second coefficient K2, the third coefficient K3, and the fourth coefficient K4, the expected frost amount Fr of the compressor 12 is calculated by the following equation.
Fr = K1 * Pm1 + K2 * Pm2 + K3 * Pm3 + K4 * Pm4

  The control unit 2 stores the expected frost amount Fr of the compressor 12 in the storage unit 202. The control unit 2 calculates the amount of frost formation when at least one of the first parameter Pm1 to the fourth parameter Pm4 is updated, and stores it in the storage unit 202. Note that the expected frost amount Fr is reset at the start of the defrosting operation.

  As shown in FIG. 3, the control unit 2 periodically compares the predicted frost formation amount with the threshold value of the frost formation amount, but is not limited thereto. For example, when the expected frost amount is updated while performing regular comparisons, the expected frost amount is compared with the threshold value for the frost amount, and the predicted frost amount is equal to or greater than the threshold value for the frost amount. The defrosting operation may be performed when

  Here, a method of calculating the first coefficient K1, the second coefficient K2, the third coefficient K3, and the fourth coefficient K4 will be described. While the environmental conditions such as the outside air temperature and humidity are aligned, the operating conditions of the refrigerator A are changed and the refrigerator A is operated. And while acquiring 1st parameter Pm1, 2nd parameter Pm2, 3rd parameter Pm3, and 4th parameter Pm4 for every driving | running condition, the amount of frost formation of the evaporator 12 is detected for every driving | running condition.

  Furthermore, after substituting the first parameter Pm1, the second parameter Pm2, the third parameter Pm3, the fourth parameter Pm4 and the frost formation amount of the evaporator 12 into the above-mentioned formula of the expected frost formation for each operating condition, the simultaneous equations are solved. The first coefficient K1, the second coefficient K2, the third coefficient K3, and the fourth coefficient K4 are calculated.

  As described above, in the refrigerator A, based on the information obtained during the cooling operation (opening / closing of the freezer compartment door 41, the cumulative driving time of the compressor 11, the number of times the damper has been continuously opened for a certain period of time), The frost formation amount (expected frost formation amount) of the evaporator 12 is calculated. In the refrigerator A, the defrosting is performed at a timing when the expected frost amount exceeds the frost amount at which the evaporator 12 starts to clog.

  In the refrigerator A of the present embodiment, the frost formation amount of the evaporator 12 that is difficult to detect directly is calculated as the expected frost formation amount based on information obtained during operation of the refrigerator A. And the control part 2 starts defrosting, when the expected frost amount reaches | attains the frost amount (threshold of frost amount) when clogging of the evaporator 12 starts. That is, the control unit 2 compares the expected frost formation amount with the threshold value of the frost formation amount, confirms the necessity of defrosting, and performs defrosting when it is determined that it is necessary. Therefore, it is possible to suppress power consumption by suppressing a problem that the frequency of the defrosting operation increases or decreases and the cooling efficiency decreases.

Second Embodiment
Another example of the refrigerator according to the present invention will be described. In the present embodiment, the configuration of the refrigerator A is the same as that of the first embodiment, the same portions are denoted by the same reference numerals, and detailed description of the same portions is omitted.

  In the refrigerator A, the first coefficient K1, the second coefficient K2, the third coefficient K3, and the fourth coefficient K4 are determined based on the results when the environmental conditions are determined assuming the installation location and the refrigerator A is operated under the environmental conditions. Have acquired. On the other hand, the assumed environmental conditions may differ from the actual environmental conditions of the installation location (for example, the humidity is higher than expected). In such a case, the amount of frost (actual frost amount) attached to the evaporator 12 due to the operation of the refrigerator A may be different from the expected frost amount. The refrigerator A of the present embodiment performs control to correct the deviation between the actual frost amount and the expected frost amount.

  In the defrosting operation, the evaporator 12 is heated by the defrost heater 16 and the frost adhering to the evaporator 12 is melted. And the control part 2 acquires the temperature of the evaporator 12 from the evaporator temperature sensor 23, and complete | finishes a defrost operation, when the temperature of the evaporator 12 reaches | attains predetermined | prescribed temperature. If the amount of frost formation of the evaporator 12 is known, it is possible to calculate the time from the start to the end of the defrosting operation. Below, the calculation method of the time from the defrosting operation start of the evaporator 12 to completion | finish is demonstrated. FIG. 7 is a diagram showing the temperature of the evaporator during the defrosting operation. FIG. 7 is a graph showing the temperature change of the evaporator 12 during the defrosting operation, where the vertical axis represents the temperature of the evaporator 12 and the horizontal axis represents the elapsed time.

  In FIG. 7, the left end is the start time of the defrosting operation, and the evaporator 12 at that time is at the temperature Th1. For example, if the temperature of the freezer compartment 4 is −18 ° C., the evaporator Th 12 at that time is −21 ° C., which is lower than the temperature of the freezer compartment 4. When the defrosting operation is completed when the temperature of the evaporator 12 reaches the temperature Th2, the temperature Th2 is a temperature at which the frost attached to the evaporator 12 is completely melted. Therefore, the temperature is set higher than 0 ° C., for example, 10 ° C.

In the graph of FIG. 7, the solid line indicates the behavior when the evaporator 12 in a state where frost is not formed by the defrost heater 16 is heated from the temperature Th1 to the temperature Th2. As shown in FIG. 7, the time required to heat the evaporator 12 without frost is Tm1. Further, when the time required to melt the frost of the amount of frosting m is time Tm2, the melting latent heat of water is h, the output of the defrosting heater 16 is W1, and the efficiency is η, the time Tm2 is expressed by the following equation: Can be obtained.
Tm2 = (h × m) / (η × W1)

And the defrosting time Tm3 required for the defrosting of the evaporator 12 of the amount of frost formation m is calculated | required by the sum of time Tm1 and time Tm2.
Tm3 = Tm1 + Tm2

In the refrigerator A, the defrosting operation is optimized by starting the defrosting when the actual frosting amount of the evaporator 12 reaches the frosting amount m1 when the frosting starts to become clogged. Frost operation. Therefore, assuming that the time required to melt the frost of the amount of frost formation m1 is time Tm21, the expected defrosting time Tm31 required for defrosting when performing an ideal defrosting operation is obtained by the following equation.
Tm21 = (h × m1) / (η × W1)
Tm31 = Tm1 + Tm21
In the initial operation of the refrigerator A, the control unit 2 employs the frost amount m1 as the frost amount threshold.

  When the control unit 2 determines that the expected frost amount has exceeded the frost amount threshold value m1 when the environment around the refrigerator A is different from the assumption or when the usage method is different from the assumption, it actually adheres to the evaporator 12. The actual frost formation amount and the expected frost formation amount (threshold amount m1 of frost formation amount) may differ. When the actual frost amount and the expected frost amount are different, there is a difference between the actual defrost time that is the actual defrost operation time and the estimated defrost time that is the defrost time of the expected frost amount. Then, the control part 2 has confirmed the shift | offset | difference of an actual frost amount and an estimated frost amount by comparing the actual defrost time which is the time of an actual defrost operation, and the assumption defrost time. When there is a difference between the actual frost amount and the expected frost amount, the control unit 2 corrects the difference between the actual defrost time and the assumed defrost time by changing the threshold value of the frost amount.

  A defrosting operation in which the deviation is corrected will be described below. FIG. 8 is a flowchart of the defrosting operation of the refrigerator according to the present invention. The control unit 2 includes, in the storage unit 202, information on an assumed defrosting time Tm31 that is a defrosting time when the frosting amount of the evaporator 12 starts to clog.

  As shown in FIG. 8, the control unit 2 calculates the expected frost formation amount from the first parameter Pm1, the second parameter Pm2, the third parameter Pm3, and the fourth parameter Pm4 (step S501). Then, it is confirmed whether the expected frost amount is equal to or more than the threshold value of the frost amount (step S502). When the expected frost amount is less than the frost amount threshold (No in step S502), the process returns to the calculation of the expected frost amount (step S501). When the predicted frost amount is equal to or greater than the frost amount threshold (Yes in step S502), the control unit 2 turns on the defrost heater 16 (step S503).

  The control unit 2 acquires the temperature of the evaporator 12 based on information from the evaporator temperature sensor 23 (step S504). And the control part 2 confirms whether the temperature of the evaporator 12 reached | attained temperature Th2 of completion | finish of defrosting (step S505). The state where the defrost heater 16 is turned on is maintained until the temperature of the evaporator 12 reaches the defrost end temperature. When the temperature of the evaporator 12 reaches the defrosting end temperature (Yes in step S505), the control unit 2 acquires the actual defrosting time that is the time required from the start to the end of the defrosting (step S506). . The actual defrosting time is acquired by the control unit 2 from the time measuring unit 201 by calculation from the time when defrosting starts and the time when it ends.

  The control unit 2 calls the assumed defrosting time Tm3 from the storage unit 202, calculates the difference between the actual defrosting time and the assumed defrosting time Tm3, and checks whether the difference is larger than the threshold value ts1 (step S507). If the difference between the actual defrosting time and the assumed defrosting time is less than the threshold value ts1 (No in step S507), the process is terminated. When the difference between the actual defrost time and the estimated defrost time Tm3 is equal to or greater than the threshold value ts1 (Yes in step S507), it is confirmed whether the actual defrost time is equal to or greater than the estimated defrost time Tm3 (step S508). When the actual defrost time is equal to or longer than the estimated defrost time Tm3 (Yes in step S508), the frost amount threshold value is changed to be small (step S509). If the actual defrost time is less than the estimated defrost time Tm3 (No in step S508), the frost amount threshold value is greatly changed (step S510).

  Thus, by changing the threshold value of the frost amount, it is possible to bring the expected frost amount calculated by the control unit 2 closer to the frost amount m1 at which the evaporator 12 starts to clog. Thereby, since the amount of frost formation of the evaporator 12 is estimated correctly and defrosting is performed based on the estimated amount of frost formation, defrosting can be performed efficiently. In addition, as a change amount of a threshold value, you may make it select from a predetermined numerical value, and you may make it acquire from the difference of real defrost time and assumption defrost time using a table. Further, it may be obtained by calculation.

<Third Embodiment>
Another example of the refrigerator according to the present invention will be described with reference to the drawings. FIG. 9 is a side sectional view of another example of the refrigerator according to the present invention, and FIG. 10 is a block diagram showing the configuration of the refrigerator shown in FIG. The refrigerator B shown in FIG. 9 has the same configuration as the refrigerator A of the second embodiment except that it includes a dew condensation prevention heater 17. Therefore, substantially the same parts as those of the refrigerator A of the refrigerator B are denoted by the same reference numerals, and detailed description of the same parts is omitted.

  As shown in FIG. 9, in the refrigerator B, a dew condensation prevention heater 17 is embedded in a front surface portion of a partition wall 101 that partitions between the refrigerator compartment 3 and the freezer compartment 4. The partition wall 101 has a configuration including a heat insulating member inside, but is not completely insulated, and is cooled by the cold air in the refrigerator compartment 3 and the freezer compartment 4. When the partition wall 101 is cooled and the temperature of the front surface becomes lower than the outside air, condensation may occur. If such condensation occurs, it may cause the growth of mold and bacteria, which is not preferable for hygiene. Moreover, there is a possibility that the user's discomfort and distrust may be promoted by dew condensation where it is easy for the user to touch.

  Therefore, in the refrigerator B, condensation is prevented by heating the front surface of the partition wall 101 with the condensation prevention heater 17. As shown in FIG. 10, the dew condensation prevention heater 17 is connected to the control unit 2, and the control unit 2 controls the operation. Next, the operation of the dew condensation prevention heater 17 will be described. In the refrigerator B, the condensation prevention heater 17 is always turned on, so that condensation can be reliably prevented, but the power consumption increases.

  For this reason, in the refrigerator B, it is preferable to drive the dew condensation prevention heater 17 when the condition is likely to cause dew condensation (for example, the outside air is hot and humid). In the refrigerator B, the control unit 2 determines the humidity from the estimated defrosting time and the actual defrosting time of the evaporator 12 by utilizing the fact that the frosting amount of the evaporator 12 varies depending on the external humidity.

  Below, the drive of the dew condensation prevention heater 17 by the control part 2 is demonstrated. FIG. 11 is a flowchart showing the condensation prevention operation of the refrigerator according to the present invention. FIG. 11 shows the operation after the defrosting operation condition, that is, the predicted frost amount is equal to or greater than the threshold value of the frost amount. The controller 2 starts the defrosting operation (step S601) and confirms the end of the defrosting operation (step S602). When the end of the defrosting operation is confirmed (Yes in step S602), the time from the start of the defrosting to the end of the defrosting, that is, the actual defrosting time is acquired (step S603). In addition, about the confirmation method of completion | finish of defrost, and the acquisition method of actual defrost time, since it has shown in 3rd Embodiment, it abbreviate | omits.

  The control unit 2 calls the assumed defrosting time from the storage unit 202, calculates the difference between the actual defrosting time and the assumed defrosting time, and checks whether the difference is larger than the threshold value ts2 (step S604). If the difference between the actual defrosting time and the assumed defrosting time is less than the threshold value ts2 (No in step S604), the process is terminated. When the difference between the actual defrosting time and the estimated defrosting time is equal to or greater than the threshold value ts2 (Yes in step S604), it is confirmed whether the actual defrosting time is equal to or longer than the estimated defrosting time (step 605).

  When the actual defrosting time is equal to or longer than the estimated defrosting time (Yes in step S605), the control unit 2 determines that the humidity around the refrigerator B is higher than the assumed humidity, and turns on the dew condensation prevention heater 17 (Step S606). Note that the operation of turning on the defrosting heater 16 includes one that continues the ON state of the dew condensation prevention heater 17.

  When the actual defrosting time is less than the estimated defrosting time (No in step S605), the control unit 2 determines that the humidity around the refrigerator B is lower than the assumed humidity, and turns off the defrosting heater 16 (Step S607). Note that the operation of turning off the dew condensation prevention heater 17 includes an operation of continuing the dew condensation prevention heater 17 in the OFF state.

  In the refrigerator B, the control unit 2 predicts the humidity around the refrigerator B by comparing the estimated defrosting time of the evaporator 12 with the actual defrosting time when the defrosting is actually performed. As described above, in the refrigerator B, the number of open / close operations of the freezer compartment door 41 from the previous defrosting operation, the cumulative open time, the cumulative drive time of the compressor 11 and the number of times of continuous drive over the predetermined time of the damper 15 are The driving of the dew condensation prevention heater 17 is controlled as necessary in anticipation of humidity. Thereby, since the refrigerator B drives the dew condensation prevention heater 17 as needed, without adding a humidity sensor etc., it can reduce power consumption.

<Fourth embodiment>
Still another example of the refrigerator according to the present invention will be described. In 3rd Embodiment, ON / OFF control of the dew condensation prevention heater 17 is performed by the magnitude of the actual defrosting time and the assumption defrosting time. When the dew condensation prevention heater 17 is variable in output, the output may be changed based on the difference between the actual defrosting time and the assumed defrosting time.

  When the actual defrosting time is shorter than the expected defrosting time, the control unit 2 determines that the frosting amount of the evaporator 12 is less than the expected frosting amount and the outside air humidity is low. Conversely, when the actual defrosting time is longer than the expected defrosting time, the control unit 2 determines that the frosting amount of the evaporator 12 is larger than the expected frosting amount and the humidity of the outside air is high.

  And the control part 2 acquires the difference of actual defrost time and assumption defrost time, and adjusts the output of the dew condensation prevention heater 17 based on the difference. For example, when the actual defrosting time is shorter than the expected defrosting time, the output of the dew condensation prevention heater 17 is lowered because the humidity of the outside air is lower than expected. Conversely, when the actual defrost time is longer than the estimated defrost time, the humidity of the outside air is higher than expected, so the output of the dew condensation prevention heater 17 is lowered. The adjustment amount of the output of the dew condensation prevention heater 17 may be obtained by calculation from the difference or may be obtained using a table.

  By adopting such a configuration, the output of the dew condensation prevention heater 17 is optimized even when control is performed such that the timing of the defrosting operation is adjusted so that the actual frost amount and the expected frost amount coincide with each other. Can be adjusted. The output adjustment of the dew condensation prevention heater 17 includes adjustment to turn off or adjustment from OFF to ON.

  In each of the embodiments described above, the expected frost amount obtained by calculation is the start of the defrosting operation when the evaporator 12 starts to clog, but is not limited to this. Instead, the frosting amount for starting the defrosting operation may be selected from a plurality of values, or may be manually input.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The embodiments of the present invention can be variously modified without departing from the spirit of the invention.

A, B Refrigerator 1 Heat insulation box 101, 102 Partition wall 11 Compressor 12 Evaporator 13 Freezer compartment fan 14 Refrigerator compartment fan 15 Damper 16 Defrost heater 161 Heater cover 17 Condensation prevention heater 2 Control unit 21 Freezer compartment temperature sensor 22 Refrigerator Room temperature sensor 23 Evaporator temperature sensor 24 Operation unit 25 Freezing room door open detection sensor 3 Refrigerating room 31 Refrigerating room door 4 Freezing room 41 Freezing room door 5 Vegetable room 51 Vegetable room door 6 Machine room 7 Refrigerant passage 71 Discharge port 72 Return Port 73 Return port 8 Refrigerant flow path 81 Discharge port

Claims (2)

A compressor operating the refrigeration cycle;
An evaporator connected to the compressor to cool the first storage chamber;
A second storage chamber cooled by the evaporator and maintained at a higher temperature than the first storage chamber;
A damper for opening and closing a cold air passage between the evaporator and the second storage chamber;
A defrosting unit that performs a defrosting operation to melt frost attached to the evaporator;
Information on at least opening / closing of the door of the first storage chamber, opening / closing of the damper and driving time of the compressor is obtained, and an expected frost formation amount of the evaporator is calculated based on these information to calculate the expected frost formation. Bei example and said control unit issues an instruction for performing the defrosting operation in the defrosting section when the amount exceeds a threshold value,
The control unit compares a predetermined defrosting time determined in advance with an actual defrosting time required for defrosting during a defrosting operation, and a range in which a difference between the assumed defrosting time and the actual defrosting time is determined in advance. When the threshold is exceeded,
The control unit changes the threshold value to a smaller value when the actual defrost time is longer than the assumed defrost time, and increases the threshold when the actual defrost time is shorter than the assumed defrost time. Refrigerator to change to value . A dew condensation prevention heater for preventing dew condensation on the outer surface is provided in a portion adjacent to the outer surface of at least one of the first storage chamber or the second storage chamber,
The controller adjusts the output of the dew condensation heater when the difference between the estimated defrost time and the actual defrost time exceeds a predetermined range,
The control unit increases the output of the dew condensation prevention heater when the actual defrost time is equal to or longer than the assumed defrost time, and outputs the output of the dew condensation prevention heater when the actual defrost time is less than the assumed defrost time. The refrigerator according to claim 1 which lowers .

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