refrigerator

Abstract

This refrigerator comprises a storage compartment in which items to be cooled are stored, a cooler which performs heat exchange between a refrigerant and air that flow through the interior thereof, to cool the air, a compressor for feeding the refrigerant to the cooler, an in-compartment blower for feeding the air cooled by the cooler into the storage compartment, a defrosting heater for melting frost adhered to the cooler, a cooler compartment accommodating the cooler, the in-compartment blower and the defrosting heater, and a control device for controlling the compressor, the in-compartment blower and the defrosting heater, wherein: the control device executes a defrosting operation if a continuous operating time of the compressor reaches a first threshold or if a cumulative integrated operating time of the compressor reaches a second threshold; and the defrosting operation comprises first control in which the operation of the compressor, the in-compartment blower and the defrosting heater is stopped, second control in which, after the first control is complete, the in-compartment blower is operated while the compressor and the defrosting heater remain stopped, and third control in which, after the second control is complete, the in-compartment blower is stopped and the defrosting heater is operated while the compressor remains stopped.

Description

Technical Field

[0001] The present disclosure relates to a refrigerator that performs a defrosting operation for removing frost adhering to a cooler.

Background Art

[0002] Conventionally, a refrigerator is provided with a cooler. The cooler is known to have a plurality of heat transfer tubes arranged so as to be orthogonal to an air flow, and a plurality of fins attached to the outer surfaces of the plurality of heat transfer tubes and arranged in parallel at a predetermined interval. The cooler of the refrigerator acts as an evaporator of a vapor compression refrigeration cycle, circulates inside the refrigerator, and cools the air passing through an air flow path formed between the plurality of fins. Specifically, in the cooler, heat exchange is performed between the refrigerant flowing inside the heat transfer tube and the air flowing through the air flow path via the tube wall of the heat transfer tube and the fins, and the air is cooled by the evaporation action of the refrigerant.

[0003] At this time, moisture in the air condenses and adheres to the outer surface of the heat transfer tube and the surface of the fins, and the moisture is further cooled to generate frost. Such frosting on the fins increases the flow resistance of the air and decreases the air volume, increases the thermal resistance of the fins and inhibits heat exchange, and becomes a factor in reducing the cooling efficiency of the cooler. Therefore, in a refrigerator equipped with a cooler, there is, for example, one equipped with an electric heating type heater in order to melt and remove the frost adhering to the fins of the cooler.

[0004] In a refrigerator with a forced cold air circulation system that cools each storage compartment such as a refrigerator compartment and a freezer compartment in the refrigerator using a common cooler, various techniques have been studied regarding the defrosting operation method. For example, Patent Document 1 discloses a first defrosting mode in which when the compressor stops, the in-cabinet blower is operated, the refrigerator compartment damper is opened, the freezer compartment damper is closed, and the defrost heater is de-energized; a second defrosting mode in which when the compressor stops, the in-cabinet blower is operated, the refrigerator compartment damper is opened, the freezer compartment damper is closed, and the defrost heater is energized; and a third defrosting means in which when the compressor stops, the in-cabinet blower is stopped, the refrigerator compartment damper is closed, the freezer compartment damper is closed, and the defrost heater is energized, and a refrigerator that executes a defrosting operation by combining these is disclosed. Patent Document 1 focuses on the fact that the refrigerator compartment is usually maintained at about 3 to 5°C, and uses the return air from the refrigerator compartment to remove frost that undergoes a phase change (melting) at 0°C. That is, in the first defrosting means and the second defrosting means, by opening the refrigerator compartment damper and operating the in-cabinet blower, the heat contained in the return air from the refrigerator compartment is used as energy to melt the frost. Patent Document 1 was thus aiming to improve the energy-saving performance during the defrosting operation in this way.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Generally, in a refrigerator, in a refrigerant circuit using a compressor, a compressor, a condenser, a decompression device, and an evaporator (cooler) are connected in this order by refrigerant pipes to form a refrigeration cycle. Also, the refrigerant flowing through the refrigerant pipes changes from a liquid to a gas-liquid two-phase state after passing through the condenser from the compressor, and the refrigerant changes from a gas-liquid two-phase state to a gas in the evaporator. The refrigerant exchanges heat with the surrounding air when it undergoes a phase change from a liquid to a gas in the evaporator. Here, when the operation of the compressor stops, among the refrigerant that was circulating in the refrigerant circuit during the operation of the compressor, the high-pressure liquid refrigerant in the condenser gasifies and flows into the evaporator, and is cooled, condensed, and liquefied by the air around the evaporator. At this time, most of the refrigerant in the refrigeration cycle remains in the evaporator. And when the refrigerant condenses and liquefies in the evaporator, the latent heat is released to the outside of the evaporator. In the refrigerator of Patent Document 1, in such a state, a defrost operation is started, and an attempt is made to supply heat to the frost adhering to the evaporator by operating the indoor blower or energizing the defrost heater. For this reason, a part of the heat quantity contained in the return air from the refrigerating chamber or the heat quantity supplied from the defrost heater is consumed for the gasification and temperature rise of the liquid refrigerant accumulated in the evaporator. Furthermore, power is consumed by operating the indoor blower or energizing the defrost heater. Therefore, in Patent Document 1, there remains room for improving the energy-saving performance.

[0007] The present disclosure has been made to solve the above problems, and an object thereof is to provide a refrigerator that improves energy-saving performance.

Means for Solving the Problems

[0008] The refrigerator according to the present disclosure includes a storage chamber for storing an object to be cooled, a temperature sensor provided in the storage room, A cooler that exchanges heat between the refrigerant flowing inside and the air to cool the air, a compressor that sends the refrigerant to the cooler, an indoor blower that sends the air cooled by the cooler to the storage chamber, a defrost heater that melts the frost adhering to the cooler, a cooler chamber in which the cooler, the indoor blower, and the defrost heater are stored, and a control device that controls the compressor, the indoor blower, and the defrost heater. The control device performs a defrost operation when the continuous operation time of the compressor reaches a first threshold time or when the cumulative integrated operation time of the compressor reaches a second threshold time. The defrost operation includes a first control for stopping the operation of the compressor, the indoor blower, and the defrost heater, a second control for operating the indoor blower while maintaining the compressor and the defrost heater in a stopped state after the first control ends, and a third control for stopping the indoor blower and operating the defrost heater while maintaining the compressor in a stopped state after the second control ends. and, in the second control, setting the rotation speed of the indoor blower to the lowest rotation speed to start the operation of the indoor blower, calculating the temperature rise gradient of the storage room at predetermined intervals based on the temperature of the storage room measured by the temperature sensor, and increasing the rotation speed of the indoor blower when the latest temperature rise gradient is less than the previous temperature rise gradient It consists of.

Effect of the Invention

[0009] According to the present disclosure, in the defrost operation, the first control, the second control, and the third control are performed in order. In the first control, by stopping the compressor, the indoor blower, and the defrost heater, defrosting is performed by the latent heat released to the outside when the refrigerant condenses and liquefies in the evaporator. In the second control, defrosting is performed by the return cold air from the storage chamber by operating the indoor blower. In the third control, defrosting is performed by starting the defrost heater. Thus, according to the present disclosure, the first control is performed before the second control and the third control, and the latent heat of the refrigeration cycle is used for defrosting. Thereby, the usage time and power consumption of the indoor blower and the defrost heater are reduced compared to the case where the first control is not performed. Therefore, the refrigerator of the present disclosure can improve the energy-saving performance.

Brief Description of the Drawings

[0010]

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Embodiments for Carrying Out the Invention

[0011] Embodiment 1. Hereinafter, embodiments will be described with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will be omitted or simplified as appropriate. Also, regarding the configuration shown in each figure, its shape, size, arrangement, etc. can be appropriately changed within the scope of this disclosure. Further, the positional relationship (for example, the vertical relationship, etc.) of each constituent member in the specification is, in principle, that when the refrigerator 1 is installed in a usable state. Here, in the following figures including FIG. 1, the dimensional relationships and shapes of each constituent member may be different from the actual ones.

[0012] FIG. 1 is a front view of the refrigerator 1 according to Embodiment 1. FIG. 2 is a schematic cross-sectional view of the refrigerator 1 according to Embodiment 1. FIG. 2 shows a cross-section of the refrigerator 1 in FIG. 1 cut along the line I-I. As shown in FIGS. 1 and 2, the refrigerator 1 according to Embodiment 1 includes a main body 2 provided with a refrigerating compartment 3, a temperature-switching compartment 4, and a freezing compartment 5. The refrigerating compartment 3, the temperature-switching compartment 4, and the freezing compartment 5 are storage compartments for storing objects to be cooled such as food. The refrigerating compartment 3 is provided at the uppermost stage of the main body 2. The freezing compartment 5 is provided at the lowermost stage of the main body 2. The temperature-switching compartment 4 is provided between the refrigerating compartment 3 and the freezing compartment 5 in the main body 2.

[0013] The main body 2 is a heat-insulating box body composed of an outer box, an inner box, and a heat-insulating member. The outer box is formed of a metal such as steel and has an opening on the front surface. The inner box is formed of resin and is fitted into the outer box from the opening of the outer box. The inside of the inner box is partitioned into each storage compartment by heat-insulating partition walls 17 and 18. Specifically, the inside of the inner box is partitioned into the refrigerating compartment 3 and the temperature-switching compartment 4 by the partition wall 17. Also, the inside of the inner box is partitioned into the temperature-switching compartment 4 and the freezing compartment 5 by the partition wall 18. The heat-insulating member is composed of, for example, foamed urethane or a vacuum heat-insulating material and is filled in the space between the outer box and the inner box. A control device 90 is provided at the upper part on the back side of the refrigerator 1. The control device 90 controls the operation of the refrigerator 1.

[0014] The refrigerator compartment 3, the temperature switching compartment 4, and the freezer compartment 5 are each provided with a door for opening and closing each storage compartment. For example, in front of the refrigerator compartment 3, a single-opening single-door refrigerator compartment door 13 is provided so as to be openable and closable. In front of the temperature switching compartment 4, a drawer-type temperature switching compartment door 14 is provided so as to be openable and closable in the front-rear direction. In front of the freezer compartment 5, a drawer-type freezer compartment door 15 is provided so as to be openable and closable in the front-rear direction. The drawer-type temperature switching compartment door 14 and the freezer compartment door 15 are configured to be openable and closable in the front-rear direction of the refrigerator 1 by sliding a frame (not shown) fixed to the door body with respect to rails (not shown) horizontally formed on the left and right inner wall surfaces of each storage compartment. Note that the configuration of the doors of each storage compartment described above is an example and is not limited thereto. For example, the refrigerator compartment door 13 may be a double-opening type or a two-door Kannon type, and the temperature switching compartment door 14 and the freezer compartment door 15 may be single-opening single-doors.

[0015] The refrigerator compartment 3 is provided with a shelf (not shown) on which objects to be cooled such as food are placed. The temperature switching compartment 4 is provided with a storage container (not shown) in which objects to be cooled can be stored, and the storage container is provided so as to be pull-outable. The storage container is supported by a frame (not shown) of the temperature switching compartment door 14 and is configured to slide in the front-rear direction in conjunction with the opening and closing of the temperature switching compartment door 14. Similar to the temperature switching compartment 4, the freezer compartment 5 is provided with a storage container (not shown) in which objects to be cooled can be stored, and the storage container is provided so as to be pull-outable.

[0016] The refrigerator compartment 3 is set to a refrigerating temperature range. The refrigerating temperature range is, for example, a temperature range of 3°C or higher and 5°C or lower. The freezer compartment 5 is set to a freezing temperature range. The freezing temperature range is a temperature range lower than the refrigerating temperature range. The freezing temperature range is a temperature range below 0°C, for example, a temperature range of -20°C or higher and -18°C or lower.

[0017] The temperature-switching compartment 4 can switch the set temperature within the range from the refrigerated temperature zone to the frozen temperature zone. In the temperature-switching compartment 4, the temperature zone inside is switched according to the usage. The temperature-switching compartment 4 is adjusted to, for example, three temperature zones: the chilled temperature zone, the supercooling temperature zone, and the soft-freezing temperature zone. Note that the temperature-switching compartment 4 may be adjusted to temperature zones other than these three temperature zones. Also, the set temperature of the temperature-switching compartment 4 can be selected by the user of the refrigerator 1. Therefore, since the user can adjust the set temperature of the temperature-switching compartment 4 according to their own lifestyle, the convenience of the user can be improved.

[0018] The chilled temperature zone is a temperature zone of 0°C or more and less than 3°C, for example, a temperature zone around 1°C. By setting the temperature inside the temperature-switching compartment 4 to this temperature zone, the temperature-switching compartment 4 can be used as a chilled compartment. The method of using the temperature-switching compartment 4 as a chilled compartment is used when the capacity of the refrigerating compartment 3 is insufficient, or when there is a large amount of food to be consumed on the same day.

[0019] The supercooling temperature zone is lower than the refrigerating compartment 3 and is a temperature zone in which food is in a supercooled state. The supercooled state means that even though the temperature of the food has reached the freezing point or below the freezing temperature, the freezing of the food does not start and the food remains in a non-frozen state. The supercooling temperature zone is, for example, a temperature zone of -3°C or more and less than 0°C, which is below the freezing point of the food. By setting the temperature inside the temperature-switching compartment 4 to this temperature zone, the temperature-switching compartment 4 can be used as a supercooling storage compartment for storing food in a supercooled state. In order to store food while maintaining its quality, it is desirable to maintain the food at as low a temperature as possible without freezing it, and such storage of food can be realized by the supercooling storage compartment. By using the temperature-switching compartment 4 as a supercooling storage compartment, the user can store fresh foods such as meat or fish, or foods with a short shelf life such as processed products thereof, without freezing them.

[0020] The soft freezing temperature range is a temperature range of -10°C or higher and -5°C or lower, for example, a temperature range around -7°C. By setting the temperature in the temperature switching chamber 4 to this temperature range, the temperature switching chamber 4 can be used as a soft freezing chamber. In the soft freezing temperature range, even if food is stored for a long time, the surface does not become too hard, so it is possible to easily crush or break the food. Therefore, the user can immediately use the food stored in the soft freezing chamber. The method of using the temperature switching chamber 4 as a soft freezing chamber is simply used when using the freezer.

[0021] An operation panel 6 is provided on the refrigerator door 13. The operation panel 6 is composed of an operation unit 6a for setting the temperature in each storage chamber, etc., and a display unit 6b for displaying temperature information such as the temperature and set temperature in each storage chamber or inventory information in the chamber (see Fig. 6). The operation unit 6a is composed of, for example, operation switches, etc., and the display unit 6b is composed of, for example, a liquid crystal display. Also, an outside air temperature sensor 46 for obtaining information on the outside air temperature is provided in this operation panel 6.

[0022] The refrigerator 1 has a cooler 21, an internal blower 22, and a defrost heater 45. A cooler chamber 23 for housing the cooler 21, the internal blower 22, and the defrost heater 45 is provided in the main body 2. The cooler 21 performs heat exchange between the refrigerant flowing inside and the air to cool the air. The internal blower 22 sends the air cooled by the cooler 21 to each storage chamber, that is, the refrigerator chamber 3, the temperature switching chamber 4, and the freezer chamber 5. The defrost heater 45 generates heat when it is energized to melt the frost deposited on the cooler. Hereinafter, the air cooled by the cooler 21 will be appropriately referred to as "cold air". Cold air for cooling each storage chamber is generated by the cooler 21, and the generated cold air is sent to each storage chamber by the internal blower 22. The cooler chamber 23 is provided in the part of the main body 2 corresponding to the back side of the refrigerator 1. Inside the cooler chamber 23, the internal blower 22 is provided above the cooler 21.

[0023] FIG. 3 is a schematic diagram of the refrigeration cycle 27 of the refrigerator 1 according to Embodiment 1. As shown in FIG. 3, the cooler 21, together with the compressor 24, the condenser 25, and the decompression device 26, constitutes the refrigeration cycle 27 of the refrigerator 1. In the refrigeration cycle 27, the compressor 24, the condenser 25, the decompression device 26, and the cooler 21 are connected in this order by refrigerant pipes. The solid-line arrow in FIG. 3 indicates the direction in which the refrigerant circulates in the refrigeration cycle 27.

[0024] The compressor 24 compresses the refrigerant into a high-temperature and high-pressure gaseous state. The compressor 24 is arranged in the machine room 28 provided at the lower part of the cooler chamber 23 on the back side of the refrigerator 1, as shown in FIG. 2. The refrigerant in a high-temperature and high-pressure state flowing out of the compressor 24 flows into the condenser 25. The condenser 25 dissipates the heat of the refrigerant flowing in from the compressor 24 and condenses the refrigerant. The condenser 25 is composed of, for example, a fin-and-tube type heat exchanger. The refrigerant condensed in the condenser 25 flows into the decompression device 26. The decompression device 26 decompresses the refrigerant flowing in from the condenser 25 into a two-phase state of liquid and gas. The decompression device 26 is composed of, for example, a capillary tube. The refrigerant in a two-phase state of liquid and gas flowing out of the decompression device 26 flows into the cooler 21. The cooler 21 evaporates the two-phase state refrigerant decompressed by the decompression device 26, and cools the air around the cooler 21 by the heat absorption action due to the evaporation of the refrigerant. That is, the cooler 21 functions as an evaporator in the refrigeration cycle 27. The cooler 21 is composed of, for example, a fin-and-tube type heat exchanger. The refrigerant flowing out of the cooler 21 returns to the compressor 24. By the above refrigeration cycle 27, the air around the cooler 21 is cooled, and cold air for cooling each storage chamber is generated.

[0025] Returning to FIG. 2 again, the main body 2 is provided with a cold air duct 29 for supplying air cooled by the cooler 21 to each storage chamber. The cold air duct 29 connects each of the refrigerator compartment 3, the temperature switching compartment 4, and the freezer compartment 5 to the cooler compartment 23. In the cooler compartment 23, the air flows in the air flow direction D1 from below the cooler 21 upward by the operation of the internal blower 22. The inlet of the cold air duct 29 communicates with the downstream side of the internal blower 22 in the cooler compartment 23. The cold air duct 29 branches midway from the inlet and connects to each storage chamber.

[0026] At the connection portion between the cold air duct 29 and the refrigerator compartment 3, a refrigerator compartment damper 31 for opening and closing the outlet of the cold air duct 29 to the refrigerator compartment 3 is provided. By changing the opening degree of the refrigerator compartment damper 31, the air volume of the cold air supplied to the refrigerator compartment 3 can be adjusted. At the connection portion between the cold air duct 29 and the temperature switching compartment 4, a temperature switching compartment damper 32 for opening and closing the outlet of the cold air duct 29 to the temperature switching compartment 4 is provided. By changing the opening degree of the temperature switching compartment damper 32, the air volume of the cold air supplied to the temperature switching compartment 4 can be adjusted. At the connection portion between the cold air duct 29 and the freezer compartment 5, a freezer compartment damper 33 for opening and closing the outlet of the cold air duct 29 to the freezer compartment 5 is provided. By changing the opening degree of the freezer compartment damper 33, the air volume of the cold air supplied to the freezer compartment 5 can be adjusted. The cold air generated by the cooler 21 is blown into the cold air duct 29 by the internal blower 22. Then, the cold air is supplied from the cold air duct 29 to the refrigerator compartment 3 through the refrigerator compartment damper 31, supplied from the cold air duct 29 to the temperature switching compartment 4 through the temperature switching compartment damper 32, and supplied from the cold air duct 29 to the freezer compartment 5 through the freezer compartment damper 33.

[0027] The refrigerator compartment 3 is provided with a refrigerator compartment temperature sensor 34 for detecting the temperature inside the refrigerator compartment 3. The refrigerator compartment temperature sensor 34 is provided, for example, on the inner wall surface on the back side of the refrigerator compartment 3. The temperature switching chamber 4 is provided with a temperature switching chamber temperature sensor 35 for detecting the temperature inside the temperature switching chamber 4. The temperature switching chamber temperature sensor 35 is provided, for example, on the inner wall surface on the back side of the temperature switching chamber 4. The freezer compartment 5 is provided with a freezer compartment temperature sensor 36 for detecting the temperature inside the freezer compartment 5. The freezer compartment temperature sensor 36 is provided, for example, on the inner wall surface on the back side of the freezer compartment 5. The refrigerator compartment temperature sensor 34, the temperature switching chamber temperature sensor 35, and the freezer compartment temperature sensor 36 are composed of, for example, thermistors.

[0028] In addition, the main body 2 is provided with a refrigerator compartment return air duct 40, a switching chamber return air duct 50, and a freezer compartment return air duct 60. The refrigerator compartment return air duct 40 is a duct for guiding the air inside the refrigerator compartment 3 to the cooler chamber 23. The switching chamber return air duct 50 is a duct for guiding the air inside the temperature switching chamber 4 to the cooler chamber 23. The freezer compartment return air duct 60 is a duct for guiding the air inside the freezer compartment 5 to the cooler chamber 23. The refrigerator compartment return air duct 40, the switching chamber return air duct 50, and the freezer compartment return air duct 60 are provided independently of each other.

[0029] The refrigerator compartment return air duct 40 has a refrigerator compartment return air duct inlet 42 that opens into the refrigerator compartment 3. The refrigerator compartment return air duct inlet 42 is provided away from the air outlet of the cold air duct 29 in the refrigerator compartment 3. The refrigerator compartment return air duct inlet 42 is provided on the inner wall surface on the back side of the refrigerator compartment 3. The refrigerator compartment return air duct 40 has a refrigerator compartment return opening 41 that opens into the cooler chamber 23. The refrigerator compartment return opening 41 is formed, for example, on the front wall 223 which is the front side wall of the cooler chamber 23. The refrigerator compartment return opening 41 is provided at a position upstream of the cooler 21 with respect to the air flow direction D1 in the cooler chamber 23. The air inside the refrigerator compartment 3 flows from the refrigerator compartment return air duct inlet 42 through the refrigerator compartment return air duct 40 and into the cooler chamber 23 from the refrigerator compartment return opening 41.

[0030] The switchable compartment return air duct 50 has a switchable compartment return air duct inlet 52 that opens into the temperature switchable compartment 4. The switchable compartment return air duct inlet 52 is provided on the inner wall surface on the rear side of the temperature switchable compartment 4. The switchable compartment return air duct inlet 52 is provided in the temperature switchable compartment 4 away from the outlet of the cool air duct 29. The switchable compartment return air duct 50 has a first switchable compartment return port 51A, a second switchable compartment return port 51B, and a third switchable compartment return port 51C that open into the front wall 223 of the cooler compartment 23, and includes a first branch air duct 50A, a second branch air duct 50B, and a third branch air duct 50C. Specifically, the switchable compartment return air duct 50 branches midway from one switchable compartment return air duct inlet 52 to the cooler compartment 23, leading to multiple switchable compartment return ports, namely the first switchable compartment return port 51A, the second switchable compartment return port 51B, and the third switchable compartment return port 51C. The first branched air passage 50A is the section from the branching point of the switching compartment return air passage 50 to the first switching compartment return port 51A. The second branched air passage 50B is the section from the branching point of the switching compartment return air passage 50 to the second switching compartment return port 51B. The third branched air passage 50C is the section from the branching point of the switching compartment return air passage 50 to the third switching compartment return port 51C.

[0031] The first switchable compartment return port 51A, the second switchable compartment return port 51B, and the third switchable compartment return port 51C are provided in the cooler compartment 23 facing the cooler 21 and at different positions relative to the air flow direction D1. The first switchable compartment return port 51A is located at the most upstream side of the cooler compartment 23 in the air flow direction D1. The second switchable compartment return port 51B is located downstream of the first switchable compartment return port 51A. The third switchable compartment return port 51C is located downstream of the second switchable compartment return port 51B. The first switchable compartment return port 51A, the second switchable compartment return port 51B, and the third switchable compartment return port 51C are all located downstream of the refrigerator compartment return port 41 and upstream of a freezer compartment return port 61, which will be described later, in the air flow direction D1. In other words, the first switching chamber return port 51A, the second switching chamber return port 51B, and the third switching chamber return port 51C are formed in this order from the upstream side to the downstream side in the air flow direction D1.

[0032] The air in the temperature switching chamber 4 flows from the return air duct inlet 52 of the switching chamber through any one of the first branch air duct 50A, the second branch air duct 50B, or the third branch air duct 50C, and flows into the cooler chamber 23 from any one of the first switching chamber return port 51A, the second switching chamber return port 51b, or the third switching chamber return port 51C. Note that the first branch air duct 50A, the second branch air duct 50B, and the third branch air duct 50C may each have an independent return air duct inlet of the switching chamber and be configured independently of each other. Note that the return air duct 50 of the switching chamber may be branched into at least two of the first branch air duct 50A, the second branch air duct 50B, and the third branch air duct 50C.

[0033] The return air duct 60 of the freezer compartment has a return air duct inlet 62 that opens into the freezer compartment 5. The return air duct inlet 62 of the freezer compartment is provided away from the air outlet of the cold air duct 29 in the freezer compartment 5. The return air duct inlet 62 of the freezer compartment may be provided on the inner wall surface on the back side of the freezer compartment 5. The return air duct 60 of the freezer compartment has a return port 61 of the freezer compartment that opens into the front wall 223 of the cooler chamber 23. The return port 61 of the freezer compartment is provided at a position downstream of the return port 41 of the refrigerator compartment with respect to the air flow direction D1 in the cooler chamber 23 and facing the cooler 21. The return port 61 of the freezer compartment is downstream of the return port 41 of the refrigerator compartment with respect to the air flow direction D1 in the cooler chamber 23, and is further provided downstream of the third switching chamber return port 51C. The air in the freezer compartment 5 flows from the return air duct inlet 62 of the freezer compartment through the return air duct 60 of the freezer compartment and into the cooler chamber 23 from the return port 61 of the freezer compartment.

[0034] FIG. 4 is a rear view showing the structure of the cooler chamber 23 of the refrigerator 1 according to Embodiment 1. With reference to FIG. 4, the arrangement of the return port 41 of the refrigerator compartment, the first switching chamber return port 51A, the second switching chamber return port 51b, the third switching chamber return port 51C, and the return port 61 of the freezer compartment in the cooler chamber 23 will be described in detail.

[0035] As shown in Fig. 4, the cooler 21 disposed in the cooler chamber 23 includes a plurality of heat transfer tubes 71 with smooth surfaces and provided with a plurality of thin plate-like fins 214, and a plurality of connecting tubes 72 formed in a U shape. The heat transfer tubes 71 are arranged in the vertical direction. For example, eight heat transfer tubes 71 are arranged along the vertical direction. Two adjacent heat transfer tubes 71 in the vertical direction are connected at one end in the left-right direction by a connecting tube 72. Thereby, a continuous refrigerant pipe is formed. The refrigerant flowing through the refrigerant pipe of the cooler 21 flows from the cooler inlet side 73 connected to the lowermost heat transfer tube 71 to the cooler outlet side 74 connected to the uppermost heat transfer tube 71. Since the air flow direction D1 is from below to above the cooler 21, the lowermost heat transfer tube 71 is arranged on the most upstream side among the plurality of heat transfer tubes 71 with respect to the air flow direction D1. Also, the uppermost heat transfer tube 71 is arranged on the most downstream side among the plurality of heat transfer tubes 71 with respect to the air flow direction D1. Therefore, the low-temperature gas-liquid two-phase refrigerant flowing in from the pressure reducing device 26 flows through the heat transfer tube 71 on the most upstream side with respect to the air flow direction D1 from the cooler inlet side 73, and gradually flows through the downstream heat transfer tubes 71 to reach the cooler outlet side 74. The two-phase refrigerant flowing through the cooler 21 exchanges heat with the air flowing outside the heat transfer tube 71 as it proceeds from the cooler inlet side 73 to the cooler outlet side 74. Thereby, the two-phase refrigerant flows through the heat transfer tube 71 while the liquid phase in the refrigerant evaporates. Usually, the temperature of the refrigerant at the cooler inlet side 73 is lower than the temperature of the refrigerant at the cooler outlet side 74.

[0036] In the cooler chamber 23, five regions are set, namely, the lowermost region 75 of the cooler chamber, the lower region 76 of the cooler, the middle-lower region 77 of the cooler, the middle-upper region 78 of the cooler, and the upper region 79 of the cooler. The lowermost region 75 of the cooler chamber is the region located below the cooler 21 in the cooler chamber 23 and is the region located on the most upstream side in the cooler chamber 23 with respect to the air flow direction D1. The lower region 76 of the cooler, the middle-lower region 77 of the cooler, the middle-upper region 78 of the cooler, and the upper region 79 of the cooler are all regions located at positions overlapping the cooler 21 in the cooler chamber 23. The lower region 76 of the cooler is located at the lowermost position, the middle-lower region 77 of the cooler is located above the lower region 76 of the cooler, and the middle-upper region 78 of the cooler is located above the middle-lower region 77 of the cooler. The upper region 79 of the cooler is located at the uppermost position among these four regions. With respect to the air flow direction D1, the lower region 76 of the cooler, the middle-lower region 77 of the cooler, the middle-upper region 78 of the cooler, and the upper region 79 of the cooler are arranged in this order from the upstream side.

[0037] The return port 41 of the refrigerating chamber is provided, for example, in the lowermost region 75 of the cooler chamber as a position on the upstream side of the cooler 21 with respect to the air flow direction D1 in the cooler chamber 23. Further, the return port 61 of the freezing chamber is provided, for example, in the upper region 79 of the cooler chamber as a position on the downstream side of the return port 41 of the refrigerating chamber and facing the cooler 21 with respect to the air flow direction D1 in the cooler chamber 23. The plurality of switching chamber return ports are provided, for example, in the lower region 76 of the cooler, the middle-lower region 77 of the cooler, and the middle-upper region 78 of the cooler respectively as positions facing the cooler 21 and different from each other with respect to the air flow direction D1 in the cooler chamber 23. Specifically, the third switching chamber return port 51C is provided in the middle-upper region 78 of the cooler, the second switching chamber return port 51B is provided in the middle-lower region 77 of the cooler, and the first switching chamber return port 51A is provided in the lower region 76 of the cooler.

[0038] Due to such differences in arrangement, the "heat exchange distance", which is the distance for heat exchange to occur from the air returning from each storage chamber to the cooler chamber 23 until it flows out after flowing into the cooler 21, changes, and the heat transfer area where the air returning from each storage chamber and the cooler 21 perform heat exchange changes. Usually, the temperature inside the refrigerator 1 has the relationship: temperature in the refrigerating chamber 3 > temperature in the temperature switching chamber 4 > temperature in the freezing chamber 5. Therefore, it is necessary to cool the most the "refrigerating chamber return air", which is the air returning from the refrigerating chamber 3 to the cooler chamber 23, and then it is necessary to cool a large amount of the "temperature switching chamber return air", which is the air returning from the temperature switching chamber 4 to the cooler chamber 23. And the amount of cooling the "freezing chamber return air", which is the air returning from the freezing chamber 5 to the cooler chamber 23, is considered to be minimized.

[0039] By providing the refrigerating chamber return opening 41 of the refrigerating chamber return air duct 40 in the lowermost region 75 of the cooler chamber, the refrigerating chamber return air passes from the inlet to the outlet of the cooler 21, that is, from the upstream end to the downstream end of the cooler 21 in the air flow direction D1. Therefore, the heat exchange distance between the refrigerating chamber return air and the cooler 21 becomes the longest, and the heat transfer area between the refrigerating chamber return air and the cooler 21 also becomes the largest.

[0040] On the other hand, by providing the freezing chamber return opening 61 of the freezing chamber return air duct 60 in the upper region 79 of the cooler, the freezing chamber return air passes from the portion between the upstream end and the downstream end of the cooler 21 in the air flow direction D1 to the downstream end. Therefore, the heat exchange distance between the freezing chamber return air and the cooler 21 becomes relatively short, and the heat transfer area with the cooler 21 can be suppressed. Thereby, it is prevented that the freezing chamber return air is cooled too much by the cooler 21, and by performing the necessary minimum heat exchange, the heat load of the cooler 21 is reduced.

[0041] Furthermore, the first return air opening 51A, the second return air opening 51B, and the third return air opening 51C of the return air duct 50 of the switching chamber are provided between the lower region 76 of the cooler and the upper-middle region 78 of the cooler. Therefore, the heat exchange distance between the temperature-switching chamber return air and the cooler 21 is shorter than the heat exchange distance between the refrigerator compartment return air and the cooler 21, and longer than the heat exchange distance between the freezer compartment return air and the cooler 21. Thereby, the return air of the temperature-switching chamber can be cooled by the cooling capacity between the cooling capacity of the refrigerator compartment return air and the cooling capacity of the freezer compartment return air in the cooler 21. And by optimizing and minimizing the heat exchange amount in this way, the temperature difference between the cooler 21 and the air can also be optimized, and frosting on the cooler 21 can be suppressed.

[0042] Also, a cooler chamber temperature sensor 47 for measuring the cooler chamber temperature is provided in the cooler chamber 23. The cooler chamber temperature is the temperature of the air in the cooler chamber 23. The cooler chamber temperature sensor 47 transmits the measurement result to the control device.

[0043] FIG. 5 is a schematic cross-sectional view showing the structure of the cooler compartment 23 of the refrigerator 1 according to Embodiment 1. As shown in FIG. 5, the plurality of fins 214 attached to the cooler 21 in the cooler compartment 23 are each plate-shaped in a rectangular parallelepiped shape in the cross-section in the depth direction of the cooler compartment 23. The plurality of fins 214 are each arranged such that the longitudinal direction in the cross-section in the depth direction is along the depth direction of the refrigerator 1. The plurality of fins 214 are each arranged such that the short side direction in the cross-section in the depth direction is along the height direction of the refrigerator 1. The plurality of fins 214 are stacked in the height direction of the refrigerator 1. With the cooler 21 accommodated in the cooler compartment 23, the front surfaces of the plurality of fins 214 face the front wall 223 which is the wall on the front side of the cooler compartment 23. The plurality of fins 214 are arranged so as to face the first switching chamber return port 51A, the second switching chamber return port 51B, and the third switching chamber return port 51C formed in the front wall 223 of the cooler compartment 23. Also, a part of the plurality of fins 214 is arranged so as to face the freezer compartment return port 61 formed in the front wall 223 of the cooler compartment 23. With the cooler 21 accommodated in the cooler compartment 23, the back surfaces of the plurality of fins 214 face the back wall 224 which is the wall on the back side of the cooler compartment 23.

[0044] The fin 214 is arranged at a position facing the first switching chamber return port 51A. The first switching chamber return port 51A is located on the most downstream side in the air flow direction D1 among the plurality of switching chamber return ports.

[0045] Also, as shown in FIGS. 4 and 5, the refrigerator 1 has, as an air duct switching device, a first branch air duct damper 81A, a second branch air duct damper 81B, and a third branch air duct damper 81C. The first branch air duct damper 81A is provided in the first branch air duct 50A and is a damper that opens and closes the first switching chamber return port 51A of the first branch air duct 50A. The second branch air duct damper 81B is provided in the second branch air duct 50B and is a damper that opens and closes the second switching chamber return port 51B of the second branch air duct 50B. The third branch air duct damper 81C is provided in the third branch air duct 50C and is a damper that opens and closes the third switching chamber return port 51C of the third branch air duct 50C.

[0046] By opening any one of the first branch air duct damper 81A, the second branch air duct damper 81B, or the third branch air duct damper 81C and closing the remaining two, any one of the first switching chamber return ports 51A, the second switching chamber return port 51b, or the third switching chamber return port 51C is opened and the remaining two are closed. Thereby, it is possible to switch to any one of the plurality of first branch air ducts 50A, second branch air ducts 50B, and third branch air ducts 50C. Further, by closing all of the first branch air duct damper 81A, the second branch air duct damper 81B, and the third branch air duct damper 81C, all of the first switching chamber return port 51A, the second switching chamber return port 51b, and the third switching chamber return port 51C are closed. Thereby, the flow of the return air in the switching chamber return air duct 50 can be blocked.

[0047] FIG. 6 is a functional block diagram showing the refrigerator 1 according to Embodiment 1. As shown in FIG. 6, the control device 90 is electrically connected to each of the operation panel 6, the indoor blower 22, the compressor 24, the refrigerator compartment damper 31, the temperature switching compartment damper 32, the freezer compartment damper 33, the refrigerator compartment temperature sensor 34, the temperature switching compartment temperature sensor 35, the freezer compartment temperature sensor 36, the first branch air duct damper 81A, the second branch air duct damper 81B, and the third branch air duct damper 81C, the defrost heater 45, and the cooler compartment temperature sensor 47, for example, by signal lines. Detection signals from each of the refrigerator compartment temperature sensor 34, the temperature switching compartment temperature sensor 35, the freezer compartment temperature sensor 36, the outside air temperature sensor 46, and the cooler compartment temperature sensor 47, as well as operation signals from the operation unit of the operation panel 6 are input to the control device 90. Based on each input signal, the control device 90 controls the output of the compressor 24, the air volume of the indoor blower 22, the opening degree of each damper, and the energization state of the defrost heater 45 according to a pre-stored operation program so that the interiors of the refrigerator compartment 3, the temperature switching compartment 4, and the freezer compartment 5 are maintained at the set temperatures respectively. The control device 90 outputs a display signal regarding the temperature etc. of each storage compartment to the display unit of the operation panel 6 based on each input signal.

[0048] FIG. 7 is a functional block diagram related to temperature control by the control device 90 of the refrigerator 1 according to Embodiment 1. As shown in FIG. 7, in Embodiment 1, the control device 90 includes a temperature setting unit 91, a temperature acquisition unit 92, an equipment control unit 93, and a storage unit 94. Various data and operation programs used for temperature control are stored in the storage unit 94.

[0049] The control device 90 executes a normal operation and a defrost operation. The normal operation is an operation for cooling the object to be cooled in the refrigerator 1. The defrost operation is an operation for removing the frost attached to the cooler 21.

[0050] The temperature setting unit 91 sets the set temperatures of the storage compartments of the refrigerator compartment 3, the temperature switching compartment 4, and the freezer compartment 5 according to the operation signals from the operation unit of the operation panel 6. The temperature acquisition unit 92 compares, during normal operation, the set temperatures of the respective storage compartments set by the temperature setting unit 91 with the indoor temperatures detected by the temperature sensors provided in the respective storage compartments, and outputs the comparison results to the device control unit 93. The temperature acquisition unit 92 compares the set temperature of the refrigerator compartment 3 with the indoor temperature detected by the refrigerator compartment temperature sensor 34. Also, the temperature acquisition unit 92 compares the set temperature of the temperature switching compartment 4 with the indoor temperature detected by the temperature switching compartment temperature sensor 35. Also, the temperature acquisition unit 92 compares the set temperature of the freezer compartment 5 with the indoor temperature detected by the freezer compartment temperature sensor 36. The device control unit 93 controls, during normal operation, the compressor 24, the internal blower 22, the refrigerator compartment damper 31, the temperature switching compartment damper 32, and the freezer compartment damper 33, as well as the first branch air passage damper 81A, the second branch air passage damper 81B, and the third branch air passage damper 81A so that the indoor temperature detected by the temperature sensors provided in the respective storage compartments becomes the set temperature based on the comparison results by the temperature acquisition unit 92. Also, the temperature acquisition unit 92 acquires, during the defrost operation, the measurement results of the refrigerator compartment temperature sensor 34, the temperature switching compartment temperature sensor 35, the freezer compartment temperature sensor 36, the outside air temperature sensor 46, and the cooler compartment temperature sensor 47, and outputs them to the device control unit 93. The device control unit 93 controls, during the defrost operation, the compressor 24, the internal blower 22, the defrost heater 45, the refrigerator compartment damper 31, the temperature switching compartment damper 32, and the freezer compartment damper 33, as well as the first branch air passage damper 81A, the second branch air passage damper 81B, and the third branch air passage damper 81A based on the measurement results of the respective sensors output from the temperature acquisition unit 92.

[0051] The air passage in normal operation will be described in detail. Based on the reference temperature of the temperature switching chamber 4, the control device 90 causes the first branch air passage damper 81A, the second branch air passage damper 81B, and the third branch air passage damper 81C to switch the first branch air passage 50A, the second branch air passage 50B, and the third branch air passage 50C. As the reference temperature of the temperature switching chamber 4, the set temperature of the temperature switching chamber 4 set by the temperature setting unit 91 is used, and based on this set temperature, the first branch air passage 50A, the second branch air passage 50B, and the third branch air passage 50C to be switched are selected. In the storage unit 94, for example, data in which the set temperature of the temperature switching chamber 4 and the branch air passage suitable for the set temperature are associated is stored in advance. The device control unit 93 refers to the set temperature of the temperature switching chamber 4 set by the temperature setting unit 91 and the data stored in the storage unit 94, and selects which of the first branch air passage 50A, the second branch air passage 50B, and the third branch air passage 50C to switch to. Then, the device control unit 93 controls the first branch air passage damper 81A, the second branch air passage damper 81B, and the third branch air passage damper 81C of the air passage switching device so as to switch to the selected return air passage of the switching chamber.

[0052] The set temperature of the temperature switching chamber 4 and the return air duct of the switching chamber are associated as follows, for example. The first branch air duct 50A, the second branch air duct 50B, and the third branch air duct 50C each have a first switching chamber return port 51A, a second switching chamber return port 51B, and a third switching chamber return port 51C provided at mutually different positions with respect to the air flow direction D1. When the set temperature of the temperature switching chamber 4 is relatively high, the branch air duct having the switching chamber return port located more upstream in the air flow direction D1 is associated. When the set temperature of the temperature switching chamber 4 is relatively low, the branch air duct having the switching chamber return port located more downstream in the air flow direction D1 is associated. When the set temperature of the temperature switching chamber 4 is relatively high, it is considered that the amount of cooling required to cool the air returning from the temperature switching chamber 4 to the cooler chamber 23 increases. Therefore, by allowing the air returning from the temperature switching chamber 4 to flow into the cooler 21 from the switching chamber return port located more upstream with respect to the air flow direction D1, a sufficient heat exchange distance in the cooler 21 can be ensured and the necessary cooling can be performed. On the other hand, when the set temperature of the temperature switching chamber 4 is relatively low, the air returning from the temperature switching chamber 4 is made to flow into the cooler 21 from the switching chamber return port located downstream with respect to the air flow direction D1. As a result, the heat exchange distance in the cooler 21 is not extended more than necessary, and it is possible to limit it to securing the minimum necessary heat exchange distance and reduce the heat load on the cooler 21.

[0053] The temperature switching chamber 4 can be adjusted to three temperature zones, and is provided with a first switching chamber return port 51A, a second switching chamber return port 51B, and a third switching chamber return port 51C through which air in three temperature ranges flows. For example, when the temperature switching chamber 4 is set to the chilled temperature zone, it is set so that the first branch air passage 50A having the first switching chamber return port 51A arranged on the most upstream side with respect to the air flow direction D1 is selected. When the temperature switching chamber 4 is set to the supercooled temperature zone, it is set so that the second branch air passage 50B having the second switching chamber return port 51B arranged upstream of the first switching chamber return port 51A with respect to the air flow direction D1 is selected. Further, when the temperature switching chamber 4 is set to the soft freezing temperature zone, it is set to select the third branch air passage 50C having the third switching chamber return port 51C arranged on the most downstream side with respect to the air flow direction D1. The heat exchange distance is the longest for the heat exchange between the return air of the temperature switching chamber and the cooler 21 when the temperature switching chamber 4 is set to the chilled temperature zone, and is the second longest for the heat exchange between the return air of the temperature switching chamber and the cooler 21 when the temperature switching chamber 4 is set to the supercooled temperature zone. And the heat exchange distance between the return air of the temperature switching chamber and the cooler 21 is the shortest when the temperature switching chamber 4 is set to the soft freezing temperature zone.

[0054] Based on such a relationship, the control device 90 switches the three branch air ducts. For example, when the set temperature of the temperature switching chamber 4 is in the first temperature range included in the chilled temperature range, the control device 90 opens only the first branch air duct damper 81A, opens the first switching chamber return port 51A, and switches to the first branch air duct 50A. Further, when the set temperature of the temperature switching chamber 4 is in the second temperature range included in the supercooling temperature range lower than the first temperature range, the control device 90 opens only the second branch air duct damper 81B, opens the second switching chamber return port 51B, and switches to the second branch air duct 50B. Further, when the set temperature of the temperature switching chamber 4 is in the third temperature range included in the soft freezing temperature range lower than the second temperature range, the control device 90 opens only the third branch air duct damper 81C, opens the third switching chamber return port 51C, and switches to the third branch air duct 50C. Note that the state in which only the first branch air duct damper 81A is open corresponds to the "first state" of the air duct switching device of the present disclosure, and the state in which only the second branch air duct damper 81B is open corresponds to the "second state" of the air duct switching device of the present disclosure.

[0055] FIG. 8 is a diagram showing an example of the hardware configuration of the control device 90 of the refrigerator 1 according to the first embodiment. As shown in FIG. 8, the functions of the control device 90 are realized, for example, as a processing circuit of the hardware configuration. The functions of the control device 90 are realized, for example, by the processor 95 executing a program stored in the memory 96. Further, the functions of the control device 90 may be realized by a plurality of processors and a plurality of memories cooperating with each other. Further, a part of the functions of the control device 90 may be implemented as an electronic circuit, and the other part may be realized using the processor 95 and the memory 96.

[0056] In this way, the refrigerator 1 is configured such that the return air from the temperature switching chamber 4 can have its set temperature switched within a wide range from the refrigerating temperature zone to the freezing temperature zone. The air passage through which air returns from the temperature switching chamber 4 to the cooler chamber 23 is switched to a switching chamber return air passage having a switching chamber return opening at an appropriate position among the switching chamber return openings that open at different positions with respect to the air flow direction D1 based on the set temperature of the temperature switching chamber 4. Thereby, according to the set temperature of the temperature switching chamber 4, an appropriate distance and heat transfer area for heat exchange between the air returning from the temperature switching chamber 4 to the cooler chamber 23 and the cooler 21 can be ensured. By having the air returning from the temperature switching chamber 4 to the cooler chamber 23 and the cooler 21 perform the minimum necessary heat exchange in this way, the heat load on the cooler 21 can be suppressed, and accordingly, the amount of work of the compressor 24 that constitutes the refrigeration cycle 27 together with the cooler 21 can be suppressed.

[0057] Also, all of the switching chamber return openings of the plurality of branch air passages are arranged on the downstream side of the refrigerator chamber return opening 41 and the upstream side of the freezer chamber return opening 61 with respect to the air flow direction D1. With such a configuration, the distance for heat exchange between the air returning from the temperature switching chamber 4 to the cooler chamber 23 and the cooler 21 can be adjusted to be within the range between the distance for heat exchange between the air returning from the refrigerator chamber 3 to the cooler chamber 23 and the cooler 21 and the distance for heat exchange between the air returning from the freezer chamber 5 to the cooler chamber 23 and the cooler 21. Thereby, corresponding to the temperature in the range from the refrigerating temperature zone to the freezing temperature zone that can be set in the temperature switching chamber 4, a distance for heat exchange between the air returning from the temperature switching chamber 4 to the cooler chamber 23 and the cooler 21 can be ensured.

[0058] In addition, the temperature switching chamber 4 can be switched to at least three temperature zones, namely a chilled temperature zone of 0°C or more and less than 3°C, a supercooling temperature zone of -3°C or more and less than 0°C, and a soft freezing temperature zone of -10°C or more and -5°C or less. With such a configuration, the temperature switching chamber 4 can be used as a chilled chamber, a supercooling storage chamber, or a soft freezing chamber. For example, when used as a chilled chamber, it can compensate for the insufficient capacity of the refrigerator compartment 3. When used as a supercooling storage chamber, fresh food and the like can be stored while maintaining their quality. Also, when used as a soft freezing chamber, food can be frozen and stored in a manner that allows it to be used immediately. Therefore, the convenience for the user of the refrigerator 1 can be improved.

[0059] Next, the movement of air in the cooler chamber 23 will be described. In the cooler chamber 23, the return air from the refrigerator compartment 3, the return air from the temperature switching chamber 4, and the return air from the freezer compartment 5 flow in.

[0060] The return air from the refrigerator compartment is air in the refrigerated temperature zone. The return air from the refrigerator compartment flows into the cooler chamber 23 through the refrigerator compartment return port 41 formed in the front wall 223 of the cooler chamber 23 and reaches the most upstream position of the cooler 21. The air flowing in from the refrigerator compartment return port 41 moves upward in the cooler chamber 23 and reaches the most upstream side of the cooler 21, where it exchanges heat with the cooler 21.

[0061] The return air from the temperature switching chamber is air in a temperature range corresponding to the set temperature of the temperature switching chamber 4 set from the refrigerated temperature zone to the frozen temperature zone. The return air from the temperature switching chamber flows into the cooler chamber 23 through any one of a plurality of switching chamber return ports 51 formed in the front wall 223 of the cooler chamber 23 by switching the branch air passage to any one of them. The plurality of switching chamber return ports guide the return air from the temperature switching chamber in the temperature range closest to the refrigerated temperature zone on the upstream side in the air flow direction D1, and guide the return air from the temperature switching chamber in a temperature range closer to the frozen temperature zone as it goes downstream in the air flow direction D1.

[0062] When the temperature switching chamber 4 is set to the temperature range closest to the refrigerated temperature zone, the return air of the temperature switching chamber flows into the cooler chamber 23 from the first return port 51A for the switching chamber formed in the front wall 223 of the cooler chamber 23. When the temperature switching chamber 4 is set to the temperature range closest to the refrigerated temperature zone, for example, it is the case when it is set to the chilled temperature zone. The return air of the temperature switching chamber from the first return port 51A is the return air of the temperature switching chamber in the relatively highest temperature range. The first return port 51A for the switching chamber is downstream of the return port 41 for the refrigerated chamber in the air flow direction D1 and is arranged on the most upstream side among the plurality of return ports for the switching chambers. The air flowing in from the first return port 51A for the switching chamber reaches the fins 214 attached at a position facing the first return port 51A for the switching chamber and exchanges heat with the cooler 21 through the fins 214.

[0063] When the temperature switching chamber 4 is set to the intermediate temperature range between the refrigerated temperature zone and the frozen temperature zone, the return air of the temperature switching chamber flows into the cooler chamber 23 from the second return port 51B for the switching chamber. When the temperature switching chamber 4 is set to the intermediate temperature range between the refrigerated temperature zone and the frozen temperature zone, for example, it is the case when it is set to the subcooled temperature zone. The second return port 51B for the switching chamber is downstream of the first return port 51A for the switching chamber in the air flow direction D1 and is arranged upstream of the third return port 51C for the switching chamber. The air flowing in from the second return port 51B for the switching chamber exchanges heat with the cooler 21 through the fins 214 attached at a position facing the second return port 51B for the switching chamber.

[0064] When the temperature switching chamber 4 is set to the temperature range closest to the refrigeration temperature zone, the return air of the temperature switching chamber flows into the cooler chamber 23 from the return port 51C of the third switching chamber. When the temperature switching chamber 4 is set to the temperature range closest to the refrigeration temperature zone, for example, it is the case when it is set to the soft freezing temperature zone. The return air of the temperature switching chamber from the return port 51C of the third switching chamber is the return air of the temperature switching chamber in the lowest temperature range. The return port 51C of the third switching chamber is downstream of the return port 51B of the second switching chamber in the air flow direction D1, and is arranged on the most downstream side in the air flow direction D1 among the plurality of return ports of the switching chambers. The air flowing in from the return port 51C of the third switching chamber exchanges heat with the cooler 21 through the fins 214 attached at a position facing the return port 51C of the third switching chamber.

[0065] The return air of the freezer compartment is the air in the refrigeration temperature zone. The return air of the freezer compartment flows into the cooler chamber 23 from the return port 61 of the freezer compartment formed on the front wall 223 of the cooler chamber 23 and located on the most downstream side of the cooler 21 in the air flow direction D1. The air flowing in from the return port 61 of the freezer compartment reaches the fins 214 provided at a position facing the return port 61 of the freezer compartment, and exchanges heat with the cooler 21 through the fins 214.

[0066] The air guided from the return port 41 of the refrigerator compartment, the return port 51A of the first switching chamber, and the return port 51B of the second switching chamber is the air in the relatively high temperature range among the return air of the temperature switching chamber. The air guided from the return port 51C of the third switching chamber and the return port 61 of the freezer compartment is the air in the relatively low temperature range among the return air of the temperature switching chamber. The temperature difference between the air in the relatively high temperature range among the return air of the temperature switching chamber and the cooler 21 that exchanges heat with this air is larger than the temperature difference between the air in the relatively low temperature range and the cooler 21 that exchanges heat with this air. On the other hand, for the air in the relatively low temperature range among the return air of the temperature switching chamber, the temperature difference between this air and the cooler 21 that exchanges heat with it is smaller than the temperature difference between the air in the relatively high temperature range and the cooler 21.

[0067] Note that the control device 90 controls the air duct switching device based on the set temperature as the reference temperature of the temperature switching chamber 4, but it is not limited to this. The reference temperature of the temperature switching chamber 4 may be the measured indoor temperature of the temperature switching chamber 4. For example, the control device 90 may control the air duct switching device based on the indoor temperature detected by a temperature switching chamber temperature sensor 35 that detects the temperature inside the temperature switching chamber 4. With such a configuration, when the temperature switching chamber 4 is opened and outside air flows in, causing the indoor temperature to rise significantly, the branch air duct can be switched according to the risen temperature. Also, heat exchange between the return air of the temperature switching chamber and the cooler 21 can be performed with a cooling capacity corresponding to the risen temperature. Further, the reference temperature of the temperature switching chamber 4 may be, for example, the average value of the set temperature of the temperature switching chamber 4 and the measured indoor temperature. The reference temperature of the temperature switching chamber 4 may be based on at least one of the set temperature of the temperature switching chamber 4 and the measured indoor temperature.

[0068] Also, the number of temperature zones adjusted in the temperature switching chamber 4 and the number of branch air ducts were the same in the above description, but they are not particularly limited. For example, when the number of temperature zones adjusted in the temperature switching chamber 4 is three, the number of branch air ducts may be two. In this case, as an example, when the temperature zone of the temperature switching chamber 4 is either the chilled temperature zone or the supercooled temperature zone, it may be switched to a switching chamber branch air duct having a return port of the switching chamber located upstream with respect to the air flow direction D1 in the cooler chamber 23. Also, when the temperature zone of the temperature switching chamber 4 is the soft freezing temperature zone, it may be switched to a branch air duct having a return port of the switching chamber located downstream with respect to the air flow direction D1.

[0069] Next, the defrost operation in the refrigerator 1 of Embodiment 1 will be described. When the continuous operation time of the compressor 24 has elapsed the first threshold time, or when the cumulative operation time counted from the end of the previous defrost operation of the compressor 24 has elapsed the second threshold time, the control device 90 shifts from the normal operation to start the defrost operation. The first threshold time is a time determined in advance by experiments or the like, and is a time when there is a high possibility that the cooler 21 is frosted. Similarly, the second threshold time is a time determined in advance by experiments or the like, and is a time when there is a high possibility that the cooler 21 is frosted. In the defrost operation, the first control, the second control, and the third control are performed.

[0070] In the first control, the control device 90 stops the operations of the compressor 24 and the indoor blower 22. Further, the control device 90 maintains the defrost heater 45 in a non-energized state. Furthermore, the control device 90 closes the refrigerator compartment damper 31, the temperature switching compartment damper 32, the freezer compartment damper 33, the branch air duct damper 81A, the second branch air duct damper 81B, and the third branch air duct damper 81C. After the compressor 24 stops, the high-pressure liquid refrigerant accumulated in the condenser 25 during the operation of the compressor 24 gasifies and flows into the cooler 21, where it releases heat and condenses. In the first control, this condensation latent heat is used for defrosting the cooler 21. When the first end condition is satisfied, the control device 90 ends the first control and starts the second control. The first end condition is, for example, that a predetermined time has elapsed since the start of the first control. The predetermined time in the first end condition is the time during which refrigerant condensation occurs in the cooler 21, and is about 2 to 3 minutes, for example. Note that the effective time for defrosting using the condensation latent heat varies somewhat depending on the amount of refrigerant enclosed in the refrigerant circuit and the capabilities of each component of the refrigerant circuit such as the compressor 24 and the condenser 25, but the heat lost by melting the frost is not the dominant factor determining the effective time for defrosting using the condensation latent heat. Therefore, the predetermined time in the first end condition is fixed at about 2 to 3 minutes. Hereinafter, in the defrost operation, the period during which the first control is performed may be referred to as the latent heat utilization period.

[0071] In the second control, the control device 90 maintains the compressor 24 in a stopped state and the defrost heater 45 in a non-energized state. Also, the control device 90 operates the indoor blower 22. Further, when the indoor temperature of the temperature switching chamber 4 is higher than 0°C, the control device 90 opens any one of the first switching chamber return port 151A, the second switching chamber return port 151B, and the third switching chamber return port 151C in the same manner as in normal operation, and allows the return air in the switching chamber return air passage 150 to pass through. Also, the control device 90 opens, for example, the refrigerator damper 31 and the temperature switching chamber damper 32 within a range where the stored items in each storage chamber do not freeze.

[0072] Here, the temperature of the cooler 21 during defrosting shows a value substantially equal to the temperature of the frost. The temperature change of the frost consists of (1) the sensible heat change portion from when the frost reaches 0°C from a negative temperature, (2) the latent heat change portion that is constant at 0°C during the melting of the frost (during the phase change from solid to liquid), and (3) the sensible heat change portion where the temperature becomes higher than 0°C after the frost has completely melted. The specific heat of frost, that is, ice, is about 2 kJ / (kg·K), the latent heat of fusion of frost is about 335 kJ / kg, and the specific heat of water is about 4.2 kJ / (kg·K). Therefore, when melting the frost on the cooler 21 of the refrigerator 1, a very large amount of heat is required during the latent heat change (phase change). Also, during defrosting, especially when there is a relatively large amount of frost, the time during which the temperature of the cooler 21 remains constant at 0°C tends to be longer. In other words, it can be said that frost is a heat source that can absorb a very large amount of heat when undergoing a phase change that is constant at 0°C.

[0073] Therefore, by circulating the air having a temperature higher than 0°C in the refrigerator 1 through the indoor blower 22 within the refrigerator 1, it can be used as the melting energy for melting the frost. In particular, in addition to the effect of melting the frost with the heat quantity of the return air from the storage chamber having a temperature higher than 0°C, by causing the air having a temperature higher than 0°C in the refrigerator 1 to convect within the cooler chamber 23 by the indoor blower 22, the heat transfer efficiency between the cooler 21 and the air is increased.

[0074] When the second end condition is satisfied, the control device 90 ends the second control and starts the third control. The second end condition is determined by the temperature states of the respective storage chambers in the refrigerator 1. Details of the second control, such as the damper opened in the second control and the second end condition, will be described later. Hereinafter, in the defrosting operation, the period during which the second control is performed may be referred to as the in-cabinet blower operation period.

[0075] In the third control, the control device 90 maintains the compressor 24 in a stopped state and stops the operation of the in-cabinet blower 22. Also, the control device 90 energizes and operates the defrost heater 45. The defrost heater 45 is continuously energized during the third control. Further, the control device 90 closes the refrigerator damper 31, the temperature switching chamber damper 32, and the freezer damper 33. In the third control, the cooler 21 is defrosted by the heat generated from the defrost heater 45.

[0076] When the third end condition is satisfied, the control device 90 ends the third control and returns the operation mode of the refrigerator 1 to the normal operation before the defrosting operation. The third end condition is that the cooler chamber temperature detected by the cooler chamber temperature sensor 47 reaches the end threshold temperature Tdef-end. The end threshold temperature Tdef-end is set, for example, around 10°C to 15°C, although it also depends on the size of the cooler 21. The reason why the end threshold temperature Tdef-end is a value greater than 0°C is that, as described above, a large amount of thermal energy is required for the melting of frost. The heat capacity required for the rise in the cooler chamber temperature is different from the heat capacity required for the melting of frost, and a large amount of heat is required for the melting of frost. Therefore, if the end threshold temperature is set to a temperature close to 0°C, there is a risk that the temperature of the cooler chamber temperature sensor 47 will reach the frost removal completion temperature before the frost is completely melted, and the defrosting operation will end without the frost being completely melted. Hereinafter, in the defrosting operation, the period during which the third control is performed may be referred to as the defrost heater operation period.

[0077] FIG. 9 is a flowchart showing the defrosting operation of the refrigerator 1 according to Embodiment 1. The flow of the defrosting operation will be described with reference to FIG. 9. First, the control device 90 determines whether the time during which the compressor 24 has been continuously operating has elapsed the first threshold time or whether the cumulative operating time of the compressor 24 has elapsed the second threshold time (step S101). If the condition of step S101 is not satisfied (step S101: NO), the control device 90 repeats the process until step S101 is satisfied.

[0078] If step S101 is satisfied (step S101: YES), the control device 90 determines to start the defrosting operation (step S102). The control device 90 first performs a first control as the defrosting operation (step S103). Subsequently, the control device 90 determines whether the first end condition is satisfied (step S104). If the first end condition is not satisfied (step S104: NO), the control device 90 continues the first control (step S103).

[0079] If the first end condition is satisfied (step S104: YES), the control device 90 performs a second control (step S105). Subsequently, the control device 90 determines whether the second end condition is satisfied (step S106). If the second end condition is not satisfied (step S106: NO), the control device 90 continues the second control (step S105).

[0080] If the second end condition is satisfied (step S106: YES), the control device 90 performs a third control (step S107). Subsequently, the control device 90 determines whether the third end condition is satisfied (step S108). If the third end condition is not satisfied (step S108: NO), the control device 90 continues the third control (step S107).

[0081] If the third end condition is satisfied (step S108: YES), the control device 90 ends the defrosting operation and returns the operation mode of the refrigerator 1 to the normal operation (step S109).

[0082] Figures 10 to 14 are flowcharts showing the second control of the refrigerator 1 according to the first embodiment. Here, the second control will be described in detail with reference to FIGS. 10 to 14. In FIGS. 10 to 14, a series of processes for the second control are shown. Further, in FIGS. 10 to 14, the case where there are two types of storage compartments with a set temperature of 0°C or higher, namely the refrigerating compartment 3 and the temperature switching compartment 4, is taken as an example. FIG. 11 shows the processes related to the refrigerating compartment 3, and FIG. 12 shows the processes related to the temperature switching compartment 4. Also, the processes shown in FIG. 12 and the processes shown in FIG. 13 are executed in parallel following the processes shown in FIG. 11.

[0083] First, the operation of the internal blower 22 is performed, and as shown in FIG. 10, the second control is started (step S201). Note that the rotational speed of the internal blower 22 can be set in the range of 1200 rpm to 2300 rpm, and at the stage when the internal blower 22 starts operating, it is set to the minimum rotational speed for control. The control device 90 starts measuring the outside air temperature T-ATth by the outside air temperature sensor 46 (step S202). Next, the control device 90 starts measuring the refrigerating compartment temperature T-Rth using the temperature sensor provided in the refrigerating compartment 3 (step S203). Similarly, the control device 90 starts measuring the temperature switching compartment temperature T-Sth using the temperature sensor provided in the temperature switching compartment 4 (step S204). Subsequently, the control device 90 acquires the time resolution Δt of each temperature sensor from the storage unit 94 (step S205). Further, the control device 90 checks the storage compartment in which the set temperature is set to 0°C or higher among the refrigerating compartment 3 and the temperature switching compartment 4 (step S206). Note that in the subsequent processes, the case where both the refrigerating compartment 3 and the temperature switching compartment 4 have a set temperature of 0°C or higher is taken as an example. Then, the control device 90 initializes each flag used in the subsequent processes (step S207). That is, the control device 90 sets 0 to each of the refrigerating compartment 3 flag R, the temperature switching compartment 4 flag S, the refrigerating compartment temperature gradient flag Z1, and the temperature switching compartment temperature gradient flag Z2.

[0084] As shown in FIG. 11, the control device 90 checks whether the temperature T-Rth of the refrigerator compartment is greater than 0°C (step S208). When the temperature T-Rth of the refrigerator compartment is 0°C or lower (step S208: NO), the control device 90 closes the refrigerator compartment damper 31 (step S209) to prevent air circulation with the cooler compartment 23.

[0085] When the temperature T-Rth of the refrigerator compartment is greater than 0°C (step S208: YES), the control device 90 opens the refrigerator compartment damper 31 (step S210) and adds 1 to the refrigerator compartment 3 flag R (step S211). Further, the control device 90 initializes the in-compartment blower operation time t-fan and starts measuring the in-compartment blower operation time t-fan (step S212).

[0086] When the measurement of the in-compartment blower operation time t-fan is started, in the steps from step S213 to step S221, the control device 90 acquires the temperature of the refrigerator compartment 3 every predetermined time interval Δt and calculates the temperature rise rate of the refrigerator compartment 3 at the time interval Δt. Since it takes a certain amount of time for the frost to melt, the time interval Δt is not a short time of about several seconds but about 30 seconds to 1 minute. Specifically, the control device 90 initializes the count j (step S213). Next, the control device 90 records the temperature T-Rth of the refrigerator compartment at time t as Tr1 (step S214). Then, the control device 90 determines whether the in-compartment blower operation time t-fan is equal to or greater than the time interval Δt (step S215). When the in-compartment blower operation time t-fan is less than the time interval Δt (step S215: NO), the process is repeated until the condition of step S215 is satisfied.

[0087] When the in-compartment blower operation time t-fan is equal to or greater than the interval Δt (step S215: YES), the control device 90 records the temperature T-Rth of the refrigerator compartment at time t+Δt as Tr2 (step S216). Here, the control device 90 determines whether Tr2 is greater than 0°C (step S217). When Tr2 is 0°C or lower (step S217: NO), the control device 90 sets 0 in the refrigerator compartment 3 flag R (step S218).

[0088] When Tr2 is greater than 0°C (step S217: YES), the control device 90 subtracts Tr1 from the recorded Tr2, and further calculates the absolute value of the value obtained by dividing the result by the time interval Δt as the temperature change rate ΔTr(j) (step S219). Then, the control device 90 determines whether the count j is 0 (step S220). When the count j is not 0 (step S220: NO), the control device 90 determines whether the most recent temperature change rate ΔTr(j) is greater than or equal to the previous temperature change rate ΔTr(j - 1) (step S221).

[0089] When the count j is 0 (step S220: YES), or when the most recent temperature change rate ΔTr(j) is greater than or equal to the previous temperature change rate ΔTr(j - 1) (step S221: YES), the control device 90 adds 1 to the count j (step S222). Then, the control device 90 calculates the temperature change rate ΔTr(j) at the next time interval Δt (steps S214 to S219).

[0090] When the most recent temperature change rate ΔTr(j) is less than the previous temperature change rate ΔTr(j - 1) (step S221: NO), the control device 90 sets 1 to the refrigerator compartment temperature rate flag Z1 (step S223).

[0091] As shown in FIG. 12, the control device 90 executes the processes of steps S308 to S323 in parallel with the processes described in steps S208 to S223. The control device 90 checks whether the temperature switching chamber temperature T - Sth is greater than 0°C (step S308). When the temperature switching chamber temperature T - Sth is 0°C or less (step S308: NO), the control device 90 closes the temperature switching chamber damper 32 (step S309) to prevent air circulation with the cooler chamber 23.

[0092] When the temperature T-Sth of the temperature switching chamber is greater than 0°C (step S308: YES), the control device 90 opens the temperature switching chamber damper 32 (step S310) and adds 1 to the temperature switching chamber 4 flag S (step S311). Further, the control device 90 initializes the operation time t-fan of the indoor blower and starts measuring the operation time t-fan of the indoor blower (step S312).

[0093] When the measurement of the operation time t-fan of the indoor blower is started, in the steps from step S313 to step S321, the control device 90 acquires the temperature of the temperature switching chamber 4 every predetermined time interval Δt and calculates the temperature rise rate of the temperature switching chamber 4 at the time interval Δt. Specifically, the control device 90 initializes the count w (step S313). Next, the control device 90 records the temperature T-Sth of the temperature switching chamber at time t as Ts1 (step S314). Then, the control device 90 determines whether the operation time t-fan of the indoor blower is equal to or greater than the time interval Δt (step S315). If the operation time t-fan of the indoor blower is less than the time interval Δt (step S315: NO), the process is repeated until the condition of step S315 is satisfied.

[0094] If the operation time t-fan of the indoor blower is equal to or greater than the interval Δt (step S315: YES), the control device 90 records the temperature T-Sth of the temperature switching chamber at time t+Δt as Ts2 (step S316). Here, the control device 90 determines whether Ts2 is greater than 0°C (step S317). If Ts2 is 0°C or less (step S317: NO), the control device 90 sets 0 in the temperature switching chamber 4 flag S (step S318).

[0095] When Ts2 is greater than 0°C (step S317: YES), the control device 90 subtracts Ts1 from the recorded Ts2, and further calculates the absolute value of the value obtained by dividing the result by the time interval Δt as the temperature change rate ΔTs(w) (step S319). Then, the control device 90 determines whether the count w is 0 (step S320). When the count w is not 0 (step S320: NO), the control device 90 determines whether the most recent temperature change rate ΔTs(w) is greater than or equal to the previous temperature change rate ΔTs(w-1) (step S321).

[0096] When the count w is 0 (step S320: YES), or when the most recent temperature change rate ΔTs(w) is greater than or equal to the previous temperature change rate ΔTs(w-1) (step S321: YES), the control device 90 adds 1 to the count w (step S322). Then, the control device 90 calculates the temperature change rate ΔTs(w) at the next time interval Δt (steps S314 to S319).

[0097] When the most recent temperature change rate ΔTs(w) is less than the previous temperature change rate ΔTs(w-1) (step S321: NO), the control device 90 sets 1 in the temperature switching chamber temperature rate flag Z2 (step S323).

[0098] As shown in FIG. 13, following the processing of the aforementioned steps S223 and S323, the control device 90 determines whether the refrigerator compartment temperature gradient flag Z1 is 1 and the temperature switching compartment temperature gradient flag Z2 is 1 (step S401). When at least one of the refrigerator compartment temperature gradient flag Z1 or the temperature switching compartment temperature gradient flag Z2 is not 1 (step S401: NO), in either storage compartment, the recent temperature change gradient is greater than or equal to the temperature change gradient confirmed at the previous timing. In this case, the control device 90 executes the processing of steps S208 and S308 and continues the second control. When the refrigerator compartment temperature gradient flag Z1 is 1 and the temperature switching compartment temperature gradient flag Z2 is 1 (step S401: YES), in either storage compartment, the recent temperature change gradient is smaller than that confirmed at the previous timing, and it is determined that the efficiency of the heat exchange between the frost and the air inside the compartment has decreased. In this case, the control device 90 increases the rotational speed of the internal blower 22 by one rank (step S402). Here, one rank is a rotational speed of around 200 to 300 rpm. Then, the control device 90 initializes the refrigerator compartment temperature gradient flag Z1 and the temperature switching compartment temperature gradient flag Z2 (step S403), executes the processing of steps S208 and S308, and continues the second control.

[0099] As shown in FIG. 14, following the processing of the aforementioned steps S209, S218, S309, and S318, the control device 90 performs a flag check (step S501) and determines whether the refrigerator compartment 3 flag R is 0 and the temperature switching compartment 4 flag S is 0 (step S502). When at least one of the refrigerator compartment 3 flag R or the temperature switching compartment 4 flag S is not 0 (step S502: NO), the control device 90 executes the processing of steps S208 and S308 and continues the second control. When the refrigerator compartment 3 flag R is 0 and the temperature switching compartment 4 flag S is 0 (step S502: YES), the control device 90 ends the second control (step S503) and shifts to the third control (step S504).

[0100] As described above, the refrigerator 1 has a plurality of dampers that open and close a plurality of air outlets that blow cold air into each of the plurality of storage compartments. Further, in the second control, the control device 90 opens the damper of the storage compartment in which the temperature inside the storage compartment is maintained at a temperature higher than 0°C among the plurality of dampers based on the temperatures of the plurality of storage compartments measured by the plurality of temperature sensors, and starts the operation of the indoor blower 22. Further, the control device 90 closes the damper corresponding to the storage compartment in which the temperature inside the storage compartment has become 0°C or lower among the plurality of dampers, and when all of the plurality of dampers are closed, ends the second control and executes the third control.

[0101] FIG. 15 is a diagram for explaining the time changes of the temperature and power consumption of the cooler compartment 23 in the defrosting operation of the conventional refrigerator 201. FIG. 16 is a diagram for explaining the time changes of the temperature and power consumption of the cooler compartment 23 in the defrosting operation of the refrigerator 201 according to the first embodiment. FIG. 17 is a diagram for comparing the power consumption in the defrosting operation of the conventional refrigerator 201 and the power consumption in the defrosting operation of the refrigerator 201 according to the first embodiment. In FIG. 17, the upper part shows the power consumption in the defrosting operation of the conventional refrigerator 201, and the lower part shows the power consumption in the defrosting operation of the refrigerator 201 according to the first embodiment. The effect of suppressing the power consumption according to the first embodiment will be described with reference to FIGS. 15 to 17.

[0102] As shown in Fig. 15, in a conventional refrigerator, when the defrosting operation is started, power is immediately supplied to the defrost heater 45, and the defrosting operation is performed by the heat of the defrost heater 45. On the other hand, as shown in Fig. 16, in the defrosting operation of Embodiment 1, before the third control for supplying power to the defrost heater 45, a first control for performing defrosting using the latent heat of condensation generated in the cooler 21 and a second control for performing defrosting using the air in the storage compartment are performed. That is, in Embodiment 1, when the compressor 24 is stopped, the heat (latent heat of condensation) generated by the condensation in the cooler 21 and the heat of the return air in the storage compartment at a temperature higher than 0°C in the refrigerator 1 are used as the melting energy for melting the frost. As shown in Fig. 17, in the defrosting operation using only the defrost heater 45 employed in a general refrigerator 1, the amount of power consumption indicated by the region AR1 is required. In contrast, in Embodiment 1, by performing the first control and the second control, the amount of power consumption indicated by the region AR2 can be reduced. Further, by shortening the heater energization period, the amount of power consumption indicated by the region AR3 can be reduced. Therefore, in Embodiment 1, a defrosting operation with excellent energy saving performance can be realized.

[0103] As described above, according to Embodiment 1, in the defrosting operation, the first control, the second control, and the third control are performed in order. In the first control, by stopping the compressor 24, the indoor blower 22, and the defrost heater 45, defrosting is performed by the latent heat released to the outside when the refrigerant condenses and liquefies in the cooler 21. In the second control, defrosting is performed by the return cold air from the storage compartment by operating the indoor blower 22. In the third control, defrosting is performed by starting the defrost heater 45. Thus, according to the present disclosure, the first control is performed before the second control and the third control, and the latent heat of the refrigeration cycle 27 is used for defrosting. Thereby, compared with the case where the first control is not performed, the usage time and power consumption of the indoor blower 22 and the defrost heater 45 are reduced. Therefore, the refrigerator 1 of Embodiment 1 can improve the energy saving performance.

[0104] In particular, in recent years, with various changes in lifestyle, refrigerators having a plurality of storage compartments with different set temperatures, and refrigerators equipped with a temperature switching compartment capable of finely adjusting the set temperature to a temperature suitable for the user's preference and food ingredients have been proposed. Also, in the case of a refrigerator equipped with a temperature switching compartment, application of a technology for optimizing energy-saving performance or cooling performance is desired.

[0105] The temperature switching compartment 4 of Embodiment 1 has a function of switching the set temperature of the temperature switching compartment 4 over a wide range from the freezing temperature range to the refrigerating temperature range. As the temperature in the temperature switching compartment 4 changes, the temperature difference between the air returning from the temperature switching compartment 4 and the surface of the cooler 21 that exchanges heat with this air changes. Therefore, depending on the set state of the temperature switching compartment 4 by the user, a large temperature difference may occur when comparing the temperature in the temperature switching compartment 4 with the frost adhering to the cooler 21, and the temperature switching compartment 4 may have a refrigerating action capable of melting the frost.

[0106] In Embodiment 1, including the temperature switching compartment 4, the temperature of each storage compartment of the refrigerator 1 is measured, and by sending the air in the storage compartment where a temperature higher than 0°C is measured to the cooler 21, the air existing in the temperature switching compartment 4 is utilized to perform defrosting. Therefore, the refrigerator 1 of Embodiment 1 can improve energy-saving performance.

[0107] Also, in the first embodiment, by performing the first control before the second control, it is possible to suppress the power required to operate the indoor blower 22 in the second control. Further, while the latent heat of condensation is effective for defrosting, while performing defrosting with the latent heat of condensation, before starting the operation of the indoor blower 22, temperature equalization in the cooler chamber 23, that is, equalization of the temperature of the frost, is achieved. As a result, it is possible to remove the frost that is too cold compared to the surroundings. Generally, in the defrosting operation, there is a concern that the heat quantity will concentrate on the overly cold part, and the heat quantity cannot be effectively used for defrosting the entire cooler 21, resulting in an extended defrosting operation time. If the defrosting time extends, the operation time of the indoor blower 22 and the defrost heater 45 will extend, so there is a risk that power will be consumed unnecessarily and the energy-saving performance will deteriorate. However, in the first embodiment, by eliminating the deviation of the temperature distribution, the heat quantity can be effectively used for defrosting the entire cooler 21, and it is possible to suppress the extension of the defrosting operation time.

[0108] Also, in the second control, the control device of the first embodiment sets the rotation speed of the indoor blower 22 to the lowest rotation speed and starts the operation of the indoor blower 22. Then, based on the temperature of the storage chamber measured by the temperature sensor, the temperature rise slope of the storage chamber is calculated at regular time intervals. Each time the latest temperature rise slope becomes less than the previous temperature rise slope and the process of S402 shown in FIG. 13 is passed through, the rotation speed of the indoor blower is increased. That is, the rotation speed of the indoor blower 22 is controlled to gradually change from a low rotation speed to a high rotation speed in stages.

[0109] Generally, if the rotation speed of the indoor blower 22 is initially operated at the maximum speed, the convection in the cooler chamber 23 will become faster, so that the heat exchange between the frost and the return air cannot be performed with maximum efficiency. This is because the flow velocity of the convected air is fast, so the flow velocity of the air on the wall side of the cooler chamber 23 also becomes fast, and the heat exchange between the wall of the cooler chamber 23 and the air is also promoted. In the first embodiment, since the rotation speed of the indoor blower 22 is controlled to gradually increase from a low rotation speed to a high rotation speed, the electrical input of the indoor blower 22 can be suppressed, and furthermore, the air in each storage chamber whose temperature is set at 0 °C or higher can be evenly dispersed into the cooling chamber. Therefore, compared with the case where the rotation speed of the indoor blower 22 is initially operated at the maximum speed, the frost can be efficiently melted by the waste heat of the return cold air in the storage chamber.

[0110] Also, in the first control of the first embodiment, since the indoor blower 22 is not operating, the indoor blower 22 starts operating at the timing of shifting to the second control. At this time, if the indoor blower 22 is operated at a high rotation speed shortly after the start of the second control, there is a risk of suddenly generating a sound from the refrigerator 1 and giving discomfort to the user. In the first embodiment, the rotation speed of the indoor blower 22 is increased at regular intervals. Therefore, it is difficult for the user to feel that the operation sound of the indoor blower 22 has suddenly become loud, and it is possible to suppress giving discomfort.

[0111] FIG. 18 shows the relationship between the indoor blower operation time and the improvement rate of the annual power consumption in the refrigerator 1 according to the first embodiment. Note that even when different indoor blower operation times are set, the conditions other than the indoor blower operation time are the same.

[0112] As shown in FIG. 18, it can be seen that the longer the operation time of the internal blower, the greater the improvement rate of the annual power consumption of the refrigerator 1. Also, with the operation time of the internal blower around 20 minutes as the boundary, the slope of the improvement rate becomes gentle. This means that the improvement efficiency of the annual power consumption decreases as the operation time of the internal blower increases. That is, it shows that the air in each storage compartment where the set temperature in the refrigerator 1 is set to 0°C or higher can be effectively used for defrosting during the operation time of the internal blower 22 up to about 20 minutes.

[0113] When the operation period of the internal blower becomes 20 minutes or more, the slope of the improvement rate of the annual power consumption of the refrigerator 1 becomes gentle and the improvement efficiency drops because the internal blower 22 is operated to circulate the air in the cooler compartment 23 and each storage compartment. That is, it is considered that the air temperature in the storage compartment where the set temperature is set to 0°C or higher is cooled by the operation of the internal blower 22 and is almost around 0°C. Since a temperature higher than 0°C is more effective for defrosting, the defrosting during the operation period of the internal blower is slowed down when the air temperature in each storage compartment becomes almost around 0°C. That is, when the operation time of the internal blower 22 becomes 20 minutes or more, the effect of suppressing the energization time of the defrost heater 45 decreases, and it becomes difficult to shorten the period during which the third control for energizing the defrost heater 45 is performed. For this reason, it shows that the improvement effect of the power consumption of the defrost operation decreases and the improvement effect of the annual power consumption decreases. From such a relationship between the operation time of the internal blower and the improvement rate of the annual power consumption, the time for continuing the second control may be limited to, for example, 20 minutes.

[0114] Embodiment 2. FIG. 19 is a schematic cross-sectional view around the return air duct 150 of the switching chamber of the refrigerator 101 according to Embodiment 2. The refrigerator 101 according to Embodiment 2 is different from Embodiment 1 in that it has a switching valve instead of a damper as an air duct switching device provided in the return air duct 150 of the switching chamber. In Embodiment 2, parts common to Embodiment 1 are denoted by the same reference numerals and the description thereof is omitted.

[0115] As shown in FIG. 19, the return air duct 150 of the switching chamber of the refrigerator 201 includes a first branch air duct 150A, a second branch air duct 150B, and a third branch air duct 150C. Further, the return air duct 150 of the switching chamber of the refrigerator 201 has a first switching chamber return port 151A, a second switching chamber return port 151B, and a third switching chamber return port 151C that open to the front wall 223 of the cooler chamber 23. In the cooler chamber 23, the first switching chamber return port 151A, the second switching chamber return port 151B, and the third switching chamber return port 151C are arranged in this order from the upstream side with respect to the air flow direction D1. The return air duct 150 of the switching chamber branches on the way from one return air duct inlet 52 of the switching chamber to the cooler chamber 23 and is configured to lead to a plurality of switching chamber return ports, that is, the first switching chamber return port 151A, the second switching chamber return port 151B, and the third switching chamber return port 151C. Specifically, in the first branch portion 153 on the downstream side of the return air duct inlet 52 of the switching chamber, it branches into the first branch air duct 150A and the second branch air duct 150B and the third branch air duct 150C. Further, in the second branch portion 154 on the downstream side of the first branch portion 153, it branches into the second branch air duct 150B and the third branch air duct 150C. The first branch air duct 150A is the portion from the first branch portion 153 to the first switching chamber return port 151A. The second branch air duct 150B is the portion from the first branch portion 153 to the second switching chamber return port 151B. The third branch air duct 150C is the portion from the second branch portion 154 to the third switching chamber return port 151C.

[0116] The first switching valve 182 and the second switching valve 183 perform air duct switching by directly contacting the inner wall of the return air duct 150 of the switching chamber. The first switching valve 182 is provided in the first branch portion 153. The first switching valve 182 switches the air duct communicating with the return air duct inlet 52 of the switching chamber to either the first branch air duct 150A or the second branch air duct 150B and the third branch air duct 150C.

[0117] The second switching valve 183 is provided in the second branch portion 154. The second switching valve 183 switches the air duct communicating with the return air duct inlet 52 of the switching chamber to either the second branch air duct 150B or the third branch air duct 150C.

[0118] FIG. 20 is a functional block diagram showing the refrigerator 101 according to Embodiment 2. As shown in FIG. 20, the control device 90 is electrically connected to each of the first switching valve 182 and the second switching valve 183, for example, by signal lines. Similar to Embodiment 1, the control device 90 performs control to switch the return air duct 150 of the switching chamber based on the set temperature of the temperature switching chamber 4. At this time, the control device 90 selects the return air duct 150 of the switching chamber to be switched based on the set temperature of the temperature switching chamber 4, and controls the first switching valve 182 and the second switching valve 183 so as to switch to the selected return air duct 150 of the switching chamber.

[0119] During normal operation, the control device 90 switches the three branch air ducts in the same manner as in the first embodiment. For example, when the set temperature of the temperature switching chamber 4 is in the first temperature range included in the chilled temperature range, the control device 90 opens the first switching valve 182 in a direction that connects the return air duct inlet 52 of the switching chamber and the first branch air duct 150A, thereby opening the first return port 151A of the switching chamber and switching to the first branch air duct 150A. Further, when the set temperature of the temperature switching chamber 4 is in the second temperature range included in the subcooling temperature range that is lower than the first temperature range, the control device 90 opens the first switching valve 182 in a direction that connects the return air duct inlet 52 of the switching chamber and the second branch air duct 150B and the third branch air duct 150C, and opens the second switching valve 183 in a direction that connects the return air duct inlet 52 of the switching chamber and the second branch air duct 150B, thereby opening the second return port 51B of the switching chamber and switching to the second branch air duct 50B. Further, when the set temperature of the temperature switching chamber 4 is in the third temperature range included in the soft freezing temperature range that is lower than the second temperature range, the control device 90 opens the first switching valve 182 in a direction that connects the return air duct inlet 52 of the switching chamber and the second branch air duct 150B and the third branch air duct 150C, and opens the second switching valve 183 in a direction that connects the return air duct inlet 52 of the switching chamber and the third branch air duct 150C, thereby opening the third return port 51C of the switching chamber and switching to the third branch air duct 50C. Note that the state in which the first switching valve 182 is opened in a direction that connects the return air duct inlet 52 of the switching chamber and the first branch air duct 150A corresponds to the "first state" of the air duct switching device of the present disclosure. Further, the state in which the first switching valve 182 is opened in a direction that connects the return air duct inlet 52 of the switching chamber and the second branch air duct 150B and the third branch air duct 150C, and the second switching valve 183 is opened in a direction that connects the return air duct inlet 52 of the switching chamber and the second branch air duct 150B corresponds to the "second state" of the air duct switching device of the present disclosure.

[0120] FIG. 21 is a flowchart showing the second control of the refrigerator 101 according to Embodiment 2. The second control of Embodiment 2 will be described with reference to FIG. 21. In FIG. 21, only step S307 is added in addition to the processes described in FIG. 12, so only step S307 will be described. In step S307, the first switching valve 182 and the second switching valve 183 are controlled so as to switch to the first branch air duct 150A. At this time, it becomes possible to guide the return air of the temperature switching chamber 4 to the most upstream side in the air flow direction D1, and the return air of the temperature switching chamber 4 can be passed through the entire cooler 21. Therefore, in the configuration of Embodiment 2 having the first branch portion 153 and the second branch portion 154, although the return air duct 150 of the switching chamber cannot always be closed, the return air of the temperature switching chamber 4 can be effectively utilized during the defrosting operation. Therefore, it is possible to suppress the energization time of the defrosting heater 45 during the defrosting operation. The processes after step S308 are the same as those described in Embodiment 1.

[0121] As described above, the return air duct 150 of the switching chamber is configured to branch at the first branch portion 153 and the second branch portion 154 and connect to the first switching chamber return port 151A, the second switching chamber return port 151B, and the third switching chamber return port 151C. And in the first branch part 153 and the second branch part 154, the first switching valve 182 and the second switching valve 183 for switching the return air duct 150 of the switching chamber are provided. Therefore, according to Embodiment 2, in addition to the effects described in Embodiment 1, the number of switching mechanisms can be reduced compared to the case where dampers or the like are provided at each switching chamber return port 151 of the return air duct 150 of the switching chamber, and the air duct switching device can be configured at a lower cost.

[0122] Embodiment 3. FIG. 22 is a schematic cross-sectional view around the return air duct 150 of the switching chamber of the refrigerator 201 according to Embodiment 3. The refrigerator 201 according to Embodiment 3 is different from the refrigerator 201 in Embodiment 2 in that it further includes a freeze prevention heater for preventing freezing of the switching valve as a switching mechanism. In Embodiment 3, the same reference numerals are given to the parts common to Embodiment 1, and the description thereof is omitted.

[0123] As shown in FIG. 22, the refrigerator 201 of Embodiment 3 includes a first freeze prevention heater 184 and a second freeze prevention heater 185. The first freeze prevention heater 184 and the second freeze prevention heater 185 are, for example, electric heaters.

[0124] The first freeze prevention heater 184 is provided around the first branch portion 153 to prevent the first switching valve 182 from freezing. The second freeze prevention heater 185 is provided around the second branch portion 154 to prevent the second switching valve 183 from freezing. The first switching valve 182 and the second switching valve 183 perform the switching of the air passage by directly contacting the inner wall of the switching chamber return air passage 150. If the first switching valve 182 or the second switching valve 183 does not operate for a long period of time, it may freeze while being in contact with the inner wall of the air passage. By the first freeze prevention heater 184 and the second freeze prevention heater 185, the first branch portion 153 and the second branch portion 154 are heated respectively to prevent freezing.

[0125] FIG. 23 is a functional block diagram showing the refrigerator 201 according to Embodiment 3. As shown in FIG. 23, the control device 90 is electrically connected to the first freeze prevention heater 184 and the second freeze prevention heater 185, for example, by signal lines. The control device 90 heats and operates each of them by performing energization control of the first freeze prevention heater 184 and the second freeze prevention heater 185. The control device 90 operates the first freeze prevention heater 184 and the second freeze prevention heater 185, for example, at regular intervals.

[0126] As described in Embodiment 1, the water vapor contained in the air flowing into the cooler chamber 23 adheres to the cooler 21 as frost. When an excessive amount of frost adheres to the cooler 21, the heat exchange efficiency of the refrigeration cycle 27 decreases, and as a result, the cooling efficiency of the refrigerator 201 significantly decreases. For this reason, a defrosting heater 45 for defrosting is provided in the cooler 21.

[0127] The control device 90 operates the first anti-freezing heater 184 and the second anti-freezing heater 185 during the defrosting of the cooler 21. In particular, the control device 90 synchronizes the operations of the first anti-freezing heater 184 and the second anti-freezing heater 185 with the operation of the defrosting heater 45.

[0128] As described above, the refrigerator 201 of the third embodiment includes the first anti-freezing heater 184 and the second anti-freezing heater 185 that prevent the freezing of the first switching valve 182 and the second switching valve 183. Therefore, it is possible to prevent the first switching valve 182 and the second switching valve 183 provided in the first branch portion 153 and the second branch portion 154 from freezing and becoming inoperable.

[0129] Also, according to the third embodiment, the first anti-freezing heater 184 and the second anti-freezing heater 185 are operated during the defrosting of the cooler 21. For this reason, an increase in power consumption is suppressed as compared with the case where the first anti-freezing heater 184 and the second anti-freezing heater 185 are constantly operated. Also, when the first anti-freezing heater 184 and the second anti-freezing heater 185 are constantly operated, there is a concern that the return air passage 150 of the switching chamber is overheated and the cooling of the return air of the temperature switching chamber 4 is hindered, but this does not pose a problem during the defrosting of the cooler 21.

[0130] Also, in the third embodiment, the control device 90 synchronizes the operations of the first anti-freezing heater 184 and the second anti-freezing heater 185 with the operation of the defrosting heater 45. For this reason, the temperature of the return air of the temperature switching chamber 4 can be increased by the amount of heat generated by the operations of the first anti-freezing heater 184 and the second anti-freezing heater 185, and the heat of the return air of the temperature switching chamber 4 whose temperature has been increased can be used for the defrosting of the cooler 21. Thereby, it is possible to prevent the first switching valve 182 and the second switching valve 183 from freezing, suppress the energization time of the defrosting heater 45, and efficiently suppress the power consumption of the defrosting heater 45.

[0131] Embodiment 4. The refrigerator 1 according to Embodiment 4 differs from Embodiment 1 in that the end threshold temperature Tdef-end in the third control of the defrost operation is varied with reference to the outside air temperature.

[0132] FIG. 24 is a flowchart showing the third control of the refrigerator 1 according to Embodiment 4. The third control of Embodiment 4 will be described with reference to FIG. 24. First, the control device 90 starts the third control (step S601), and acquires the time resolution Δt from the storage unit 94 (step S602). Next, the control device 90 measures the outside air temperature T-ATth using the outside air temperature sensor 46 (step S603), and acquires the cooler chamber temperature Tdef-th using the cooler chamber temperature sensor 47 (step S604). Then, the control device 90 acquires the initial value of the end threshold temperature Tdef-end from the storage unit 94 (step S605).

[0133] The control device 90 determines whether the end threshold temperature Tdef-end is greater than the outside air temperature T-ATth (step S606). If the end threshold temperature Tdef-end is greater than the outside air temperature T-ATth (step S606: YES), the outside air temperature T-ATth is set to the end threshold temperature Tdef-end. That is, the end threshold temperature Tdef-end is changed to the outside air temperature T-ATth (step S607). If the end threshold temperature Tdef-end is less than or equal to the outside air temperature T-ATth (step S606: NO), the control device 90 does not change the end threshold temperature Tdef-end.

[0134] The control device 90 initializes the defrost operation time Tdef-time and starts measuring the defrost operation time Tdef-time (step S608). Then, the control device 90 energizes the defrost heater 45 until the cooler chamber temperature Tdef-th becomes equal to or higher than the end threshold temperature Tdef-end (steps S609 to S612).

[0135] Specifically, the control device 90 measures the cooler chamber temperature Tdef-th at time t (step S609). The control device 90 determines whether the defrost operation time Tdef-time is equal to or greater than the time interval Δt (step S610). If the defrost operation time Tdef-time is less than the time interval Δt (step S610: NO), the process is repeated until the condition of step 610 is satisfied. If the defrost operation time Tdef-time is equal to or greater than the time interval Δt (step S610: YES), the control device 90 determines whether the end threshold temperature Tdef-end is less than or equal to the cooler chamber temperature Tdef-th (step S611). If the end threshold temperature Tdef-end exceeds the cooler chamber temperature Tdef-th (step S611: NO), the control device 90 repeats the processes of steps S609 to S611. If the end threshold temperature Tdef-end is less than or equal to the cooler chamber temperature Tdef-th (step S611: YES), the defrost operation is terminated (step S612), and the operation mode is restored to the normal operation.

[0136] Note that the time interval Δt is set to be as short as possible, such as an interval of approximately 1 to 5 seconds. This is because the energy-saving performance can be improved by shortening the energization time of the defrost heater 45 as much as possible. That is, although the cooler chamber temperature Tdef-th rises due to the heat quantity from the defrost heater 45, it is desirable that the amount by which the cooler chamber temperature Tdef-th exceeds the end threshold temperature Tdef-end be as small as possible, in order to suppress a state where the cooler chamber temperature Tdef-th becomes significantly higher than the end threshold temperature Tdef-end.

[0137] Using FIGS. 25 to 27, the effects of Embodiment 4 will be described in comparison with the case where the end threshold temperature does not vary with reference to the outside air temperature. FIG. 25 is a diagram for explaining the electric input and the cooler chamber temperature during the defrost operation at low outside air temperature in a conventional refrigerator. FIG. 26 is a diagram for explaining the electric input and the cooler chamber temperature during the defrost operation at low outside air temperature in the refrigerator 1 of Embodiment 4. FIG. 27 is a diagram for comparing the lengths of the heater energization times between the conventional refrigerator and the refrigerator 1 of Embodiment 4.

[0138] In the conventional example of FIG. 25, the case where the outside air temperature is 10° C. and the end threshold temperature is fixed at 16° C. is taken as an example. As shown in FIG. 25, during the heater energization period, when the cooler chamber temperature is around 0° C. and around 10° C. of the outside air temperature, the rising slope of the cooler chamber temperature suddenly becomes gentle. During these periods, the slope of the cooler chamber temperature is almost flat and almost no temperature rise occurs.

[0139] The reason why the rising slope of the cooler chamber temperature becomes gentle near 0° C. is that, as explained in Embodiment 1, the time required to melt the frost becomes long. That is, since the frost absorbs a very large amount of heat during the phase change at 0° C., near 0° C., the amount of heat generated from the defrost heater 45 is taken away for melting the frost, and the amount of heat from the defrost heater 45 does not contribute to the rise in the cooler chamber temperature. That is, almost all of the heat amount of the defrost heater 45 is being used for melting the frost.

[0140] Also, the reason why the rising slope of the cooler chamber temperature becomes gentle around 10° C. is that the heat balance is achieved between the amount of heat (cold air intrusion amount) entering the refrigerator 1 from the outside air, that is, the cooler chamber 23, and the amount of heat generated from the defrost heater 45. When the end threshold temperature is set higher than the outside air temperature, it is necessary to raise the temperature inside the cooler chamber 23 higher than the outside air temperature. When trying to raise the temperature above the outside air temperature, the amount of heat generated from the defrost heater 45 is taken away to the outside air side, that is, part of the heat generated from the defrost heater 45 leaks out of the refrigerator 1, so the cooler chamber temperature is in a state where it is difficult to rise.

[0141] In heat conduction, heat always attempts to reach an even temperature as it moves and diffuses from a location with a higher heat quantity to a location with a lower heat quantity. Therefore, when the inside of the cooler compartment 23 is raised to the outside air temperature by the heat quantity of the defrost heater 45, the inside of the cooler compartment 23 and the outside air side reach thermal equilibrium. In this state, if an attempt is made to further increase the temperature inside the cooler compartment 23, it will disrupt the thermal equilibrium balance with the outside air side, thus requiring an even greater amount of heat, and the heat quantity being generated by energizing the defrost heater 45 is not being utilized effectively. Accordingly, in a conventional refrigerator where the end threshold temperature is fixed, the energy-saving performance may deteriorate depending on the outside air temperature.

[0142] In contrast, in Embodiment 4 of FIG. 26, the end threshold temperature is changed with reference to the outside air temperature sensor 46. For this reason, as shown in FIG. 26, during the heater energization period, only when the cooler compartment temperature is around 0°C, the temperature increase suddenly becomes gentle and has an almost flat slope. As described above, the reason the temperature increase slope of the frost detection cooler compartment temperature becomes gentle near 0°C is that a very large amount of heat is being absorbed during the phase change of the frost. That is, this indicates that the heat quantity generated from the defrost heater 45 is being taken away not by the increase in the cooler compartment temperature but by the melting of the frost, showing that defrosting is in progress.

[0143] On the other hand, as shown in FIG. 26, in Embodiment 4, there is no occurrence of a thermal equilibrium balance, and there is no region where the slope suddenly becomes gentle except when the cooler compartment temperature is around 0°C. For this reason, it can be seen that in Embodiment 4, compared to the conventional example of FIG. 25, the heat quantity supplied from the defrost heater 45 is less likely to leak to the outside air side.

[0144] FIG. 27 shows the waveforms of the cooler chamber temperature in FIGS. 25 and 26, aligned starting from the timing when the third control, i.e., energization of the defrost heater 45, is started. As shown in FIG. 27, in the case of the conventional example, when the cooler chamber temperature becomes equal to or higher than the outside air temperature, the temperature increase slope suddenly becomes gentle, and the calorific value generated by the defrost heater 45 is not effectively utilized. For this reason, the heater energization period in the conventional example is longer than the heater energization period in Embodiment 4. On the other hand, in the case of Embodiment 4, since the end threshold temperature Tdef-end is variable according to the outside air temperature, the calorific value generated by the defrost heater 45 can be effectively used for defrosting the cooler 21. For this reason, the heater energization period in Embodiment 4 is shorter than the heater energization period in the conventional example.

[0145] As described above, according to Embodiment 4, the end threshold temperature is variable according to the outside air temperature at which the refrigerator 1 is actually operating. For this reason, in addition to the effects described in Embodiment 1, the energization time of the defrost heater 45 in the third control can be shortened, the power consumption can be reduced, and the energy-saving performance can be improved.

[0146] In the refrigerator 1 of the fourth embodiment, although the configuration in which the end threshold temperature is changed according to the outside air temperature has been described, the refrigerator 1 of the fourth embodiment is basically assumed to be used indoors. For example, when the refrigerator 1 is used at a low temperature where the outside air temperature is less than 2°C, it is not necessary to change the end threshold temperature according to the outside air temperature. This is because when the outside air temperature is close to 0°C, if the end threshold temperature is changed according to the outside air temperature, there is a possibility that the defrost operation will be completed at the state of 0°C which is the frost melting temperature, and there is a possibility that the frost will not melt completely and residual frost will remain. In other words, if the outside air temperature is somewhat higher than 0°C and the amount of heat supplied from the defrost heater 45 can be effectively used, it is possible to completely melt the frost, so that the energy saving performance can be improved. Specifically, the change of the end threshold temperature according to the outside air temperature may be limited to the state where the outside air temperature is, for example, 2°C or higher. However, specifically at what temperature of the outside air the end threshold temperature is changed according to the outside air temperature may be determined in consideration of the form of the product, the usage situation of the user, etc., and instead of 2°C of the above-described outside air temperature, for example, 5°C may be used as a reference.

[0147] Also, when the heat insulation performance of the refrigerator 1 itself is low, the heat balance described in the conventional example of FIG. 25 is likely to occur. This is because if the heat insulation ability of the refrigerator 1 is high, the heat of the defrost heater 45 that generates heat inside the refrigerator 1 can suppress the leakage of the amount of heat to the outside air side which is outside the refrigerator 1. That is, the heat balance is less likely to occur in the refrigerator 1 using a high-performance heat insulating material such as a vacuum heat insulating material having a high heat insulation ability, and is more likely to occur in the inexpensive refrigerator 1 that does not use a vacuum heat insulating material. For this reason, in the fourth embodiment, a vacuum heat insulating material may be used for the heat insulating member of the refrigerator 1.

[0148] The description of the embodiments is as above. However, appropriately combining, modifying, or omitting each embodiment is also included in the scope of the technical idea disclosed in the embodiments. Also, although the object to be cooled stored in the storage chamber has been described as food in the previous description, it is not limited to this. For example, the object to be cooled may be something collected from nature, such as raw meat of small non-edible animals, or raw meat of experimental animals such as cloned animals.

[0149] Also, the number, type, and arrangement of the storage chambers of the refrigerator 1 are not limited to those described in the embodiments. For example, in addition to the refrigerating chamber 3, the refrigerator 1 may further have other refrigerating chambers such as a vegetable chamber, or may have other types of storage chambers. In this case, in Embodiment 1, when the refrigerator 1 has the refrigerating chamber 3 and the temperature switching chamber 4 as storage chambers with set temperatures set at 0°C or higher, this has been described. However, the refrigerator 1 may further have a vegetable chamber with a set temperature set between 3°C and 8°C. In this example, after the process of 207, the process corresponding to the vegetable chamber is performed in parallel with the processes of steps S208 to S223 and steps S308 to S323.

[0150] Also, in Embodiment 1, in the return air duct 150 of the temperature switching chamber 4, a process may be provided to control the first branch air duct damper 81A to be open and the second branch air duct damper 81B and the third branch air duct damper 81C to be closed. As also described in Embodiment 2, by opening only the first branch air duct damper 81A, the return cold air of the temperature switching chamber 4 can be returned to the cooler chamber 23 through the first return port 151A of the switching chamber formed upstream of the cooler 21 rather than through the second return port 151B and the third return port 151C of the switching chamber. Thereby, the amount of heat of the return cold air from the temperature switching chamber 4 can be efficiently used for defrosting the cooler 21. Since the flow of the process is the same as that of FIG. 21 in Embodiment 2, the description using a flowchart is omitted.

[0151] Also, in Embodiment 1, the configuration in which the refrigerator 1 includes the switching chamber return air duct 150 having the first branch air duct 150A, the second branch air duct 150B, and the third branch air duct 150 as the return air duct of the temperature switching chamber 4 has been described, but the present invention is not limited to this. The refrigerator 1 may have a configuration in which only one switching chamber return air duct 150 having no branch is provided as the return air duct of the temperature switching chamber 4. In this case, in the second control of the defrosting operation, the switching chamber return air duct 150 is opened.

Explanation of Signs

[0152] 1 Refrigerator, 2 Main body, 3 Refrigerating compartment, 4 Temperature switching compartment, 5 Freezing compartment, 6 Operation panel, 6a Operation part, 6b Display part, 13 Refrigerating compartment door, 14 Temperature switching compartment door, 15 Freezing compartment door, 17 Partition wall, 18 Partition wall, 21 Cooler, 22 Internal blower, 23 Cooler compartment, 24 Compressor, 25 Condenser, 26 Pressure reducing device, 27 Refrigeration cycle, 28 Machine room, 29 Cold air duct, 31 Refrigerating compartment damper, 32 Temperature switching compartment damper, 33 Freezing compartment damper, 34 Refrigerating compartment temperature sensor, 35 Temperature switching compartment temperature sensor, 36 Freezing compartment temperature sensor, 40 Refrigerating compartment return air duct, 41 Refrigerating compartment return port, 42 Refrigerating compartment return air duct inlet, 45 Defrosting heater, 46 Outside air temperature sensor, 47 Cooler compartment temperature sensor, 50 Switching compartment return air duct, 50A First branch air duct, 50B Second branch air duct, 50C Third branch air duct, 51A First switching compartment return port, 51B Second switching compartment return port, 51C Third switching compartment return port, 52 Switching compartment return air duct inlet, 60 Freezing compartment return air duct, 61 Freezing compartment return port, 62 Freezing compartment return air duct inlet, 71 Heat transfer pipe, 72 Connecting pipe, 73 Cooler inlet side, 74 Cooler outlet side, 75 Lowermost region of cooler compartment, 76 Lower region of cooler, 77 Middle-lower region of cooler, 78 Middle-upper region of cooler, 79 Upper region of cooler, 81A First branch air duct damper, 81B Second branch air duct damper, 81C Third branch air duct damper, 90 Control device, 91 Temperature setting part, 92 Temperature acquisition part, 93 Equipment control part, 94 Memory part, 95 Processor, 96 Memory, 101 Refrigerator, 150 Switching compartment return air duct, 150A First branch air duct, 150B Second branch air duct, 150C Third branch air duct, 151A First switching compartment return port, 151B Second switching compartment return port, 151C Third switching compartment return port, 153 First branching part, 154 Second branching part, 182 First switching valve, 183 Second switching valve, 184 First anti-freezing heater, 185 Second anti-freezing heater, 201 Refrigerator, 214 Fin, 223 Front wall, 224 Rear wall.

Claims

1. A storage chamber for storing an object to be cooled, a temperature sensor provided in the storage chamber, a cooler that exchanges heat between the refrigerant flowing inside and air to cool the air, a compressor that sends the refrigerant to the cooler, an in-cabinet blower that sends the air cooled by the cooler to the storage chamber, a defrost heater that melts the frost adhering to the cooler, a cooler chamber in which the cooler, the in-cabinet blower, and the defrost heater are stored, and a control device that controls the compressor, the in-cabinet blower, and the defrost heater, wherein the control device performs a defrost operation when the continuous operation time of the compressor reaches a first threshold time or when the cumulative integrated operation time of the compressor reaches a second threshold time, and the defrost operation includes a first control for stopping the operation of the compressor, the in-cabinet blower, and the defrost heater, a second control for operating the in-cabinet blower while maintaining the compressor and the defrost heater in a stopped state after the first control ends, and a third control for stopping the in-cabinet blower and operating the defrost heater while maintaining the compressor in a stopped state after the second control ends, in the second control, the rotation speed of the in-cabinet blower is set to the lowest rotation speed to start the operation of the in-cabinet blower, the temperature rise rate of the storage chamber is calculated at predetermined intervals based on the temperature of the storage chamber measured by the temperature sensor, and when the latest temperature rise rate is less than the previous temperature rise rate, the rotation speed of the in-cabinet blower is increased a refrigerator.

2. A plurality of storage chambers for storing an object to be cooled, a plurality of temperature sensors provided in each of the plurality of storage chambers, a cooler that exchanges heat between the refrigerant flowing inside and air to cool the air and generate cold air, a compressor that sends the refrigerant to the cooler, an in-cabinet blower that sends the cold air cooled by the cooler to the plurality of storage chambers, a plurality of dampers that open and close a plurality of air outlets for blowing out cold air in each of the plurality of storage chambers, a defrost heater that melts the frost adhering to the cooler, a cooler chamber in which the cooler, the in-cabinet blower, and the defrost heater are stored, and a control device that controls the compressor, the in-cabinet blower, and the defrost heater, wherein the control device When the continuous operating time of the compressor reaches a first threshold time, or when the cumulative integrated operating time of the compressor reaches a second threshold time, a defrost operation is performed. The defrost operation includes: a first control for stopping the operations of the compressor, the indoor blower, and the defrost heater; a second control for operating the indoor blower while maintaining the compressor and the defrost heater in a stopped state after the first control ends; a third control for stopping the indoor blower and operating the defrost heater while maintaining the compressor in a stopped state after the second control ends, and consists of: In the second control, opening a damper corresponding to a storage chamber in which the temperature in the storage chamber is maintained at a temperature higher than 0°C and starting the operation of the indoor blower; closing a damper corresponding to a storage chamber in which the temperature in the storage chamber has become 0°C or lower among the plurality of dampers; when all of the plurality of dampers are in a closed state, ending the second control and executing the third control Refrigerator.

3. A storage chamber for storing an object to be cooled, a cooler that exchanges heat between the refrigerant flowing inside and air to cool the air; a compressor that sends the refrigerant to the cooler; an indoor blower that sends the air cooled by the cooler to the storage chamber; a defrost heater that melts the frost adhering to the cooler; a cooler chamber in which the cooler, the indoor blower, and the defrost heater are stored; a cooler chamber temperature sensor that measures the temperature of the cooler chamber; an outside air temperature sensor that measures the outside air temperature of the refrigerator; a control device that controls the compressor, the indoor blower, and the defrost heater, and includes: The control device: When the continuous operating time of the compressor reaches a first threshold time, or when the cumulative integrated operating time of the compressor reaches a second threshold time, a defrost operation is performed. The defrost operation includes: a first control for stopping the operations of the compressor, the indoor blower, and the defrost heater; a second control for operating the indoor blower while maintaining the compressor and the defrost heater in a stopped state after the first control ends; a third control for stopping the indoor blower and operating the defrost heater while maintaining the compressor in a stopped state after the second control ends, and consists of: The control device: In the third control, Compare the temperature of the cooler chamber with the end threshold temperature to determine whether to end the defrosting operation. When the outside air temperature is equal to or lower than the end threshold temperature, set the end threshold temperature to be equal to or lower than the outside air temperature. Refrigerator.

4. A plurality of storage chambers, A plurality of temperature sensors provided in each of the plurality of storage chambers, A plurality of dampers for opening and closing a plurality of air outlets that blow cold air into each of the plurality of storage chambers, and further comprising: The control device, In the second control, Open the damper corresponding to the storage chamber in which the temperature in the storage chamber is maintained at a temperature higher than 0 ° C, and start the operation of the indoor blower. Among the plurality of dampers, close the damper corresponding to the storage chamber in which the temperature in the storage chamber has become 0 ° C or lower. When all of the plurality of dampers are in a closed state, end the second control and execute the third control. The refrigerator according to claim 1 or 3.

5. The plurality of storage chambers include a temperature switching chamber in which the set temperature can be switched within a temperature range from the freezing temperature zone to the refrigerating temperature zone. The refrigerator according to claim 2.

6. The plurality of storage chambers include a refrigerating chamber set in the refrigerating temperature zone and a freezing chamber set in the freezing temperature zone. In the cooler chamber, A first switching chamber return port through which the return air of the temperature switching chamber passes, A second switching chamber return port provided on the downstream side of the air flow relative to the first switching chamber return port, and through which the return air of the temperature switching chamber is guided, A refrigerating chamber return port provided on the upstream side of the air flow relative to the cooler, and through which the air from the refrigerating chamber passes, A freezing chamber return port that opens on the downstream side of the air flow relative to the first switching chamber return port and the second switching chamber return port, and through which the air from the freezing chamber is guided, is formed. The refrigerator according to claim 5.

7. Further comprising an air duct switching device for switching between a first state in which the return air of the temperature switching chamber is passed through the first switching chamber return port and a second state in which the return air of the temperature switching chamber is passed through the second switching chamber return port. The control device, During normal operation of cooling the object to be cooled, When the temperature of the temperature switching chamber is included in the first temperature zone, switch the air duct switching device to the first state. When the temperature of the temperature switching chamber is included in a second temperature zone lower than the first temperature zone, switch the air duct switching device to the second state. The refrigerator according to claim 6.

8. The first switching chamber return port is located on the most upstream side in the air flow direction. The control device, In the second control, causing the air duct switching device to switch to the first state The refrigerator according to claim 7.

9. Further comprising an anti-freezing heater for preventing freezing of the air duct switching device The refrigerator according to claim 7 or 8.

10. The control device is Synchronizing the timings of operating the anti-freezing heater and the defrosting heater The refrigerator according to claim 9.

11. The temperature switching chamber is switchable to a chilled temperature range of 0°C or higher and less than 3°C, a supercooled temperature range of -3°C or higher and less than 0°C, and a soft freezing temperature range of -10°C or higher and -5°C or lower The refrigerator according to claim 5.

12. A cooler chamber temperature sensor for measuring the temperature of the cooler chamber, and An outside air temperature sensor for measuring the outside air temperature of the refrigerator, and The control device is In the third control Comparing the temperature of the cooler chamber with an end threshold temperature to determine whether to end the defrosting operation, and When the outside air temperature is equal to or lower than the end threshold temperature, setting the end threshold temperature to be equal to or lower than the outside air temperature The refrigerator according to claim 1 or 2.

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