Refrigerator

Abstract

This refrigerator comprises: a first storage compartment that has been set to a first temperature; a second storage compartment that has been set to a second temperature higher than the first temperature; a cooler compartment that accommodates a cooler; a compressor; a blower; a first air passage opening / closing device that is provided in a first air passage which couples the cooler compartment and the first storage compartment; a second air passage opening / closing device that is provided in a second air passage that couples the cooler compartment and the second storage compartment; and a control device. The control device sets the first air passage opening / closing device to an open state and sets the second air passage opening / closing device to a closed state after performing a defrosting operation and then starts the compressor and the blower, and switches the second air passage opening / closing device from the closed state to the open state when the slope of the temporal change in the temperature of the first storage compartment has become negative and the temperature of the first storage compartment has fallen below the second temperature.

Description

refrigerator

[0001] The present disclosure relates to a refrigerator that stores items to be cooled in a storage compartment.

[0002] Conventionally, refrigerators are provided with a cooler for cooling objects. The cooler includes a plurality of heat transfer tubes arranged perpendicular to the air flow and a plurality of fins attached to the outer surfaces of the heat transfer tubes and arranged in parallel at regular intervals. The cooler functions as an evaporator in a vapor compression refrigeration cycle and cools air circulating inside the refrigerator and passing through an air passage formed between the fins. Specifically, in the cooler, heat is exchanged between a refrigerant flowing inside the heat transfer tubes and air flowing through the air passage via the tube walls and fins of the heat transfer tubes, and the air is cooled by the evaporation of the refrigerant.

[0003] When air is cooled by heat exchange with a refrigerant, the moisture in the air is cooled. As the moisture cools, it condenses and adheres to the surfaces of the fins, forming frost. Frost on the fins increases air flow resistance, reducing airflow, and also increases the thermal resistance of the fins, impeding heat exchange and reducing the cooling efficiency of the cooler. To melt and remove frost that has adhered to the fins of the cooler, some refrigerators, for example, are equipped with an electric heater. Refrigerators equipped with a heater periodically perform a defrosting operation to melt the frost by energizing the heater. When a refrigerator performs a defrosting operation, the temperature inside the refrigerator rises.

[0004] In a refrigerator with a forced circulation of cold air system that has multiple storage compartments, such as a refrigerator compartment and a freezer compartment, and cools the multiple storage compartments using a common cooler, an example of cooling control has been proposed that suppresses a temperature rise of frozen items after a defrosting operation (see, for example, Patent Document 1).

[0005] The refrigerator disclosed in Patent Document 1 has a first air duct switch provided in an air duct connecting a blower and a refrigerator compartment, and a second air duct switch provided in an air duct connecting the blower and the refrigerator compartment. After a defrosting operation is completed, the refrigerator disclosed in Patent Document 1 closes the first air duct switch and opens the second air duct switch for a certain period of time to cool only the freezer compartment, and then opens the first air duct switch to cool both the refrigerator compartment and the freezer compartment.

[0006] Japanese Patent Application Laid-Open No. 2015-218943

[0007] However, the refrigerator disclosed in Patent Document 1 cools the freezer compartment for a predetermined period of time before switching to control for cooling both the freezer compartment and the refrigerator compartment. This can lead to the refrigerator switching to cooling multiple storage compartments without sufficiently cooling the freezer compartment. In this case, the refrigerator's cooler generates a thermal load for additional cooling of the freezer compartment and a thermal load for cooling the refrigerator compartment. To increase the cooling capacity of the cooler to cope with such a large thermal load, the compressor must increase its rotation speed. As a result, a large load is placed on the compressor, resulting in increased power consumption.

[0008] The present disclosure has been made to solve the above-mentioned problems, and provides a refrigerator that reduces the amount of power consumption required for cooling after defrosting operation for multiple storage compartments with different set temperatures.

[0009] A refrigerator according to the present disclosure includes a first storage compartment set to a first temperature, a second storage compartment set to a second temperature higher than the first temperature, a first temperature sensor that measures the temperature of the first storage compartment, a second temperature sensor that measures the temperature of the second storage compartment, a cooler that cools air by exchanging heat between a refrigerant flowing therethrough and the air, a cooler compartment that houses the cooler, a compressor that constitutes a part of a refrigeration cycle circuit including the cooler and circulates the refrigerant through the refrigeration cycle circuit, a blower that sends the air cooled in the cooler to the first storage compartment and the second storage compartment, a defrost heater that melts frost adhering to the cooler, a first air duct opening and closing device that is provided in a first air duct connecting the cooler compartment and the first storage compartment and that opens and closes the first air duct, a second air duct opening and closing device that is provided in a second air duct connecting the cooler compartment and the second storage compartment and that opens and closes the second air duct, and a cooling device that opens and closes the first air duct. and a control device that receives as input the temperature of the first storage compartment from a temperature sensor and the temperature of the second storage compartment from the second temperature sensor, and controls the compressor, the blower, the first air duct opening and closing device, the second air duct opening and closing device, and the defrost heater, wherein the control device performs a defrosting operation by applying power to the defrost heater to melt the frost, and then executes a first control of opening the first air duct opening and closing device, closing the second air duct opening and closing device, starting the compressor and the blower, and cooling the first storage compartment until the gradient of the temperature of the first storage compartment changes over time becomes negative and the temperature of the first storage compartment becomes lower than the second temperature, and a second control of maintaining the open state of the first air duct opening and closing device and switching the second air duct opening and closing device from the closed state to the open state when the gradient of the temperature of the first storage compartment changes over time becomes negative and the temperature of the first storage compartment becomes lower than the second temperature.

[0010] According to the present disclosure, after a defrosting operation, the first storage compartment is cooled, and when the gradient of the temperature change over time in the first storage compartment is negative and the temperature of the first storage compartment is lower than the set temperature of the second storage compartment, cooling of the second storage compartment also begins. After the first storage compartment, which has a lower set temperature, is sufficiently cooled to compensate for the thermal load generated in the refrigerator by the defrosting operation, cooling of the second storage compartment, which has a higher set temperature than the first storage compartment, is performed. By gradually cooling the storage compartments from those with a lower thermal load to those with a higher thermal load, the thermal load on the cooler and the power consumption of the compressor can be reduced.

[0011] 1 is a front view of a refrigerator according to embodiment 1. FIG. 2 is a schematic cross-sectional view of the refrigerator according to embodiment 1. FIG. 3 is a schematic diagram of a refrigeration cycle circuit of the refrigerator according to embodiment 1. FIG. 4 is a rear view showing the structure of a cooler compartment of the refrigerator according to embodiment 1. FIG. 5 is a schematic cross-sectional view showing the structure of a cooler compartment of the refrigerator according to embodiment 1. FIG. 6 is a block diagram showing an example of a configuration of the refrigerator according to embodiment 1. FIG. 7 is a functional block diagram related to temperature control by a control device of the refrigerator according to embodiment 1. FIG. 8 is a diagram showing an example of a hardware configuration of the control device of the refrigerator according to embodiment 1. FIG. 9 is a timing chart showing the overall cooling control of the refrigerator according to embodiment 1. FIG. 10 is a flowchart showing the overall cooling control of the refrigerator according to embodiment 1. FIG. 11 is a flowchart showing the first half of normal cooling control of the refrigerator according to embodiment 1. FIG. 12 is a flowchart showing an operation procedure of cooling control of a temperature switchable compartment in the normal cooling control of the refrigerator according to embodiment 1. FIG. 13 is a flowchart showing an operation procedure of cooling control of a refrigerator compartment in the normal cooling control of the refrigerator according to embodiment 1. FIG. 14 is a flowchart showing an operation procedure of cooling control of a freezer compartment in the normal cooling control of the refrigerator according to embodiment 1. FIG. 15 is a flowchart showing an operation procedure of cooling control of a freezer compartment in the normal cooling control of the refrigerator according to embodiment 1. 1 is a timing chart showing temperature control of a freezer compartment in an ideal temperature control case in normal cooling control of the refrigerator according to embodiment 1. FIG. 2 is a timing chart showing a case where the temperature of a temperature switchable compartment becomes higher than a set temperature while the compressor is stopped in normal cooling control of the refrigerator according to embodiment 1. FIG. 3 is a flowchart showing an operation procedure of cooling control before a defrosting operation in the refrigerator according to embodiment 1. FIG. 4 is a flowchart showing an operation procedure of cooling control before a defrosting operation in the refrigerator according to embodiment 1. FIG. 5 is a flowchart showing an operation procedure of defrosting operation control in the refrigerator according to embodiment 1. FIG. 6 is a diagram for explaining the relationship between an electrical input and a cooler compartment temperature in a defrosting operation at a low outside air temperature in a conventional refrigerator.26. A diagram for explaining the relationship between the electric input and the cooler compartment temperature during the defrosting operation at a low outdoor air temperature in the refrigerator according to embodiment 1. A diagram for comparing the length of heater energization time between a conventional refrigerator and the refrigerator according to embodiment 1. A flowchart showing the operation procedure of cooling control after the defrosting operation of the refrigerator according to embodiment 1. A p-h diagram for explaining that the cooling control after the defrosting operation of the refrigerator according to embodiment 1 has the effect of reducing the power consumption of the compressor. A graph showing the difference in power consumption during the cooling control after the defrosting operation of the conventional refrigerator and the refrigerator according to embodiment 1. A flowchart showing an example of the operation procedure of the first half of the first control in step S111 shown in FIG. 26. A flowchart showing an example of the operation procedure of the first half of the first control in step S111 shown in FIG. 26. A flowchart showing an example of the operation procedure of the first half of the first control in step S111 shown in FIG. 26. A table showing an example of the set value of the compressor rotation speed at the start of cooling after the defrosting operation in the refrigerator according to embodiment 1. A table showing an example of the set value of the fan rotation speed at the start of cooling after the defrosting operation in the refrigerator according to embodiment 1. 26. A flowchart showing an example of a second half of the operation procedure for the first control in step S113 shown in FIG. 26. A flowchart showing an example of a second half of the operation procedure for the first control in step S113 shown in FIG. 26. A flowchart showing an example of a second half of the operation procedure for the first control in step S113 shown in FIG. 26. A flowchart showing an example of a second half of the operation procedure for the second control in step S115 shown in FIG. 26. A flowchart showing an example of an operation procedure for the second control in step S115 shown in FIG. 26. A flowchart showing an example of an operation procedure for the second control in step S115 shown in FIG. 26. A flowchart showing an example of an operation procedure for the second control in step S115 shown in FIG. 26. A flowchart showing an example of an operation procedure for the second control in step S115 shown in FIG. 26. A flowchart showing an example of an operation procedure for the third control in step S117 shown in FIG. 26. A flowchart showing an example of an operation procedure for the third control in step S117 shown in FIG. 26. A flowchart showing an example of an operation procedure for the third control in step S117 shown in FIG. 26.FIG. 27 is a flowchart showing an example of an operation procedure of the third control in step S117 shown in FIG. 26. FIG. 27 is a flowchart showing an example of an operation procedure of the third control in step S117 shown in FIG. 26. FIG. 28 is a diagram showing an example of a timing chart illustrating an operation of the cooling control after a defrosting operation in the refrigerator according to embodiment 1. FIG. 29 is a diagram showing an example of a timing chart illustrating an operation of the cooling control after a defrosting operation in the refrigerator according to embodiment 1. FIG. 29 is a diagram showing an example of a timing chart illustrating an operation of the cooling control after a defrosting operation in the refrigerator according to embodiment 1.

[0012] An embodiment of a refrigerator according to the present disclosure will be described below with reference to the drawings. In each drawing, identical or corresponding parts are designated by the same reference numerals, and their description will be omitted or simplified as appropriate. The shape, size, and arrangement of the components shown in each drawing may be changed as appropriate within the scope of this disclosure. The positional relationships of each component in the specification (e.g., the relationship between the front and back, the relationship between the left and right, and the relationship between the top and bottom) are, in principle, those when the refrigerator 1 is installed in a usable state. In the drawings, including FIG. 1, referenced for explanation, the dimensional relationships and shapes of each component may differ from the actual ones.

[0013] Embodiment 1. FIG. 1 is a front view of a refrigerator according to Embodiment 1. FIG. 2 is a schematic cross-sectional view of the refrigerator according to Embodiment 1. FIG. 2 is a schematic cross-sectional view of the refrigerator 1 shown in FIG. 1 taken along line II. As shown in FIGS. 1 and 2, the refrigerator 1 according to Embodiment 1 includes a main body 2 provided with a refrigerator compartment 3 serving as a third storage compartment, a temperature switchable compartment 4 serving as a second storage compartment, and a freezer compartment 5 serving as a first storage compartment. The refrigerator compartment 3, the temperature switchable compartment 4, and the freezer compartment 5 are each storage compartments for storing items to be cooled, such as food. The refrigerator compartment 3 is provided on the top shelf of the main body 2. The freezer compartment 5 is provided on the bottom shelf of the main body 2. The temperature switchable compartment 4 is provided in the main body 2 between the refrigerator compartment 3 and the freezer compartment 5.

[0014] The main body 2 is an insulated box composed of an outer box, an inner box, and an insulating member. The outer box is made of metal such as steel and has an opening on its front. The inner box is made of resin and is fitted into the outer box through the opening. The interior of the inner box is divided into storage compartments by insulating partition walls 17 and 18. Specifically, the interior of the inner box is divided by partition wall 17 into a refrigerator compartment 3 and a temperature switchable compartment 4. The interior of the inner box is also divided by partition wall 18 into a temperature switchable compartment 4 and a freezer compartment 5. The insulating member is made of, for example, urethane foam or vacuum insulation material, and fills the space between the outer box and the inner box. A control device 90 is provided at the upper part on the rear side of the refrigerator 1. The control device 90 controls the operation of the refrigerator 1.

[0015] The refrigerator compartment 3, the temperature switchable compartment 4, and the freezer compartment 5 each have a door for opening and closing the compartment. For example, a refrigerator compartment door 13, which is a single-leaf door, is provided in front of the refrigerator compartment 3 and can be opened and closed freely. A drawer-type temperature switchable compartment door 14 is provided in front of the temperature switchable compartment 4 and can be opened and closed freely in the front-to-back direction. A drawer-type freezer compartment door 15 is provided in front of the freezer compartment 5 and can be opened and closed freely in the front-to-back direction. The drawer-type temperature switchable compartment door 14 and the freezer compartment door 15 are configured to be opened and closed in the front-to-back direction of the refrigerator 1 by sliding a frame (not shown) fixed to the door body along a rail (not shown) formed horizontally on the left and right inner wall surfaces of each storage compartment. Note that the above-described configuration of the doors of each storage compartment is merely an example and is not limited thereto. For example, the refrigerator compartment door 13 may be a double-leaf door or a double-leaf door, and the temperature switchable compartment door 14 and the freezer compartment door 15 may be a single-leaf door.

[0016] The refrigerator compartment 3 is provided with a shelf (not shown) on which foods and other items to be cooled are placed. The temperature switchable compartment 4 is provided with a storage container (not shown) that can be pulled out and can store items to be cooled inside. The storage container is supported by a frame (not shown) of the temperature switchable compartment door 14 and is configured to slide back and forth in conjunction with the opening and closing of the temperature switchable compartment door 14. Similar to the temperature switchable compartment 4, the freezer compartment 5 is provided with a storage container (not shown) that can be pulled out and can store items to be cooled inside.

[0017] The set temperature (third temperature) of the refrigerator compartment 3 is set to the refrigeration temperature range. The refrigeration temperature range is, for example, a temperature range of 3°C or higher and 5°C or lower. The set temperature (first temperature) of the freezer compartment 5 is set to the freezing temperature range. The freezing temperature range is a temperature range lower than the refrigeration 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.

[0018] The temperature switchable compartment 4 is a storage compartment whose set temperature (second temperature) can be switched within a range from the refrigeration temperature range to the freezing temperature range. In the temperature switchable compartment 4, the temperature range can be switched depending on the purpose. The temperature switchable compartment 4 is adjusted to three temperature ranges, for example, the chilled temperature range, the supercooled temperature range, and the soft freezing temperature range. Note that the temperature switchable compartment 4 may also be adjusted to a temperature range other than these three temperature ranges. Furthermore, the set temperature of the temperature switchable compartment 4 can be selected by the user of the refrigerator 1. Therefore, the user can adjust the set temperature of the temperature switchable compartment 4 to suit their own lifestyle, thereby improving user convenience.

[0019] The chilled temperature range is a temperature range of 0° C. or higher and lower than 3° C., for example, a temperature range of around 1° C. By setting the temperature inside the temperature switchable compartment 4 to this temperature range, the temperature switchable compartment 4 can be used as a chilled compartment. Using the temperature switchable compartment 4 as a chilled compartment is used when the capacity of the refrigerator compartment 3 is insufficient or when a large amount of food is to be consumed on the same day.

[0020] The supercooling temperature zone is a temperature zone lower than the refrigeration compartment 3, where food is supercooled. A supercooled state refers to a state in which food does not begin to freeze and remains unfrozen, even when the food temperature reaches or is below the freezing point. The supercooling temperature zone is, for example, a temperature zone between -3°C and 0°C, which is below the food's freezing point. By setting the temperature inside the temperature switchable compartment 4 to this temperature zone, the temperature switchable compartment 4 can be used as a supercooling storage compartment for storing food in a supercooled state. To preserve food while maintaining its quality, it is desirable to keep the food as cold as possible without freezing it. The supercooling storage compartment enables such food preservation. By using the temperature switchable compartment 4 as a supercooling storage compartment, users can store foods with a short shelf life, such as fresh foods like meat or fish, or processed foods, without freezing.

[0021] The soft freezing temperature range is between -10°C and -5°C, for example, around -7°C. By setting the temperature inside the temperature switchable compartment 4 to this temperature range, the temperature switchable compartment 4 can be used as a soft freezing compartment. In the soft freezing temperature range, the surface of food does not become too hard even if it is stored for a long time, so the food can be easily crushed or broken. This allows the user to immediately use food stored in the soft freezing compartment. Using the temperature switchable compartment 4 as a soft freezing compartment is used when using a freezer simply.

[0022] An operation panel 6 is provided on the refrigerator compartment door 13. The operation panel 6 is composed of an operation unit 6a for setting the temperature in each storage compartment, and a display unit 6b for displaying temperature information such as the temperature and set temperature in each storage compartment, or inventory information in the storage compartment (see FIG. 6). The operation unit 6a is composed of, for example, operation switches, and the display unit 6b is composed of, for example, a liquid crystal display. The operation panel 6 also has an outside air temperature sensor 46 for obtaining information on the outside air temperature.

[0023] The refrigerator 1 includes a cooler 21, a blower 22, and a defrost heater 45. The main body 2 includes a cooler compartment 23 that houses the cooler 21, the blower 22, and the defrost heater 45. The cooler 21 exchanges heat between the refrigerant flowing therein and the air to cool the air. The blower 22 sends the air cooled by the cooler 21 to each storage compartment, i.e., the refrigerator compartment 3, the temperature switchable compartment 4, and the freezer compartment 5. The defrost heater 45 generates heat when energized to melt frost accumulated on the cooler. Hereinafter, the air cooled by the cooler 21 will be referred to as "cold air." The cooler 21 cools the air in the cooler compartment 23, generating cold air for cooling each storage compartment. The generated cold air is sent to each storage compartment by the blower 22. The cooler compartment 23 is located in the main body 2, which is on the rear side of the refrigerator 1. In the cooler chamber 23 , the blower 22 is provided above the cooler 21 .

[0024] Fig. 3 is a schematic diagram of a refrigeration cycle circuit of the refrigerator according to Embodiment 1. As shown in Fig. 3 , cooler 21, compressor 24, condenser 25, and pressure reducing device 26, constitute refrigeration cycle circuit 27 of refrigerator 1. In refrigeration cycle circuit 27, compressor 24, condenser 25, pressure reducing device 26, and cooler 21 are connected in this order by refrigerant piping. Solid arrows in Fig. 3 indicate the direction in which refrigerant circulates in refrigeration cycle circuit 27.

[0025] The compressor 24 is a device that sends the refrigerant to the cooler 21. The compressor 24 compresses the refrigerant to a high-temperature, high-pressure gas state. As shown in FIG. 2 , the compressor 24 is disposed in a machine compartment 28 that is provided below the cooler compartment 23 on the rear side of the refrigerator 1. The high-temperature, high-pressure refrigerant that flows out of the compressor 24 flows into the condenser 25. The condenser 25 dissipates heat from the refrigerant that flows in from the compressor 24, causing the refrigerant to condense. The condenser 25 is configured, for example, as a fin-and-tube heat exchanger. The refrigerant condensed in the condenser 25 flows into the pressure reducing device 26. The pressure reducing device 26 reduces the pressure of the refrigerant that flows in from the condenser 25 to a two-phase state of liquid and gas. The pressure reducing device 26 is configured, for example, as a capillary tube. The two-phase refrigerant that flows out of the pressure reducing device 26 flows into the cooler 21. The cooler 21 evaporates the two-phase refrigerant decompressed by the pressure reducing device 26, and cools the air around the cooler 21 by the heat absorption effect caused by the evaporation of the refrigerant. That is, the cooler 21 functions as an evaporator in the refrigeration cycle circuit 27. The cooler 21 is configured as, for example, a fin-and-tube heat exchanger. The refrigerant flowing out of the cooler 21 returns to the compressor 24. The above-described refrigeration cycle circuit 27 cools the air around the cooler 21, and generates cold air to cool each storage compartment.

[0026] Returning to FIG. 2 , the main body 2 is provided with a cold air duct 29 for supplying air cooled by the cooler 21 to each storage compartment. The cold air duct 29 connects the refrigerator compartment 3, the temperature switchable compartment 4, and the freezer compartment 5 to the cooler compartment 23. In the cooler compartment 23, air flows in an air flow direction D1 from below to above the cooler 21 by operation of the blower 22. An inlet of the cold air duct 29 communicates with the downstream side of the blower 22 in the cooler compartment 23. The cold air duct 29 branches from the inlet midway to form a first air duct 29a, a second air duct 29b, and a third air duct 29c. The first air duct 29a is an air duct connecting the cooler compartment 23 to the first storage compartment (freezer compartment 5). The second air passage 29b is an air passage that connects the cooler chamber 23 and the second storage chamber (temperature switchable chamber 4). The third air passage 29c is an air passage that connects the cooler chamber 23 and the third storage chamber (refrigerating chamber 3).

[0027] A connecting portion between the cold air duct 29 and the refrigerator compartment 3 is provided with a refrigerator compartment damper 31, which is a third air duct opening / closing device, that opens and closes the outlet of the cold air duct 29 to the refrigerator compartment 3. The amount of cold air supplied to the refrigerator compartment 3 can be adjusted by changing the opening degree of the refrigerator compartment damper 31. A connecting portion between the cold air duct 29 and the temperature switchable compartment 4 is provided with a temperature switchable compartment damper 32, which is a second air duct opening / closing device, that opens and closes the outlet of the cold air duct 29 to the temperature switchable compartment 4. The amount of cold air supplied to the temperature switchable compartment 4 can be adjusted by changing the opening degree of the temperature switchable compartment damper 32. A connecting portion between the cold air duct 29 and the freezer compartment 5 is provided with a freezer compartment damper 33, which is a first air duct opening / closing device, that opens and closes the outlet of the cold air duct 29 to the freezer compartment 5. The amount of cold air supplied to the freezer compartment 5 can be adjusted by changing the opening degree of the freezer compartment damper 33. The cold air generated by the cooler 21 is blown into the cold air duct 29 by the blower 22. Then, the cold air is supplied from the cold air duct 29 through the refrigerator compartment damper 31 to the refrigerator compartment 3, from the cold air duct 29 through the temperature switchable compartment damper 32 to the temperature switchable compartment 4, and from the cold air duct 29 through the freezer compartment damper 33 to the freezer compartment 5.

[0028] The refrigerator compartment 3 is provided with a refrigerator compartment temperature sensor 34, which is a third temperature sensor 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 rear side of the refrigerator compartment 3. The temperature switchable compartment 4 is provided with a temperature switchable compartment temperature sensor 35, which is a second temperature sensor for detecting the temperature inside the temperature switchable compartment 4. The temperature switchable compartment temperature sensor 35 is provided, for example, on the inner wall surface on the rear side of the temperature switchable compartment 4. The freezer compartment 5 is provided with a freezer compartment temperature sensor 36, which is a first temperature sensor 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 rear side of the freezer compartment 5. The refrigerator compartment temperature sensor 34, the temperature switchable compartment temperature sensor 35, and the freezer compartment temperature sensor 36 are each formed of, for example, a thermistor.

[0029] The main body 2 is also provided with a refrigerator compartment return air duct 40, a switchable compartment return air duct 50, and a freezer compartment return air duct 60. The refrigerator compartment return air duct 40 is an air duct for guiding air from within the refrigerator compartment 3 to the cooler compartment 23. The switchable compartment return air duct 50 is an air duct for guiding air from within the temperature switchable compartment 4 to the cooler compartment 23. The freezer compartment return air duct 60 is an air duct for guiding air from within the freezer compartment 5 to the cooler compartment 23. The refrigerator compartment return air duct 40, the switchable compartment return air duct 50, and the freezer compartment return air duct 60 are provided independently of one another.

[0030] 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 in the refrigerator compartment 3 away from the outlet of the cold air duct 29. The refrigerator compartment return air duct inlet 42 is provided on the inner wall surface on the rear side of the refrigerator compartment 3. The refrigerator compartment return air duct 40 has a refrigerator compartment return port 41 that opens into the cooler compartment 23. The refrigerator compartment return port 41 is formed, for example, in the front wall 223, which is the wall on the front side of the cooler compartment 23. The refrigerator compartment return port 41 is provided in a position in the cooler compartment 23 upstream of the cooler 21 in the air flow direction D1. Air within 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 compartment 23 through the refrigerator compartment return port 41. The refrigerator compartment return port 41 corresponds to a first return port.

[0031] 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 duct 50A is the section from the branching point of the switching compartment return air duct 50 to the first switching compartment return port 51A. The second branched air duct 50B is the section from the branching point of the switching compartment return air duct 50 to the second switching compartment return port 51B. The third branched air duct 50C is the section from the branching point of the switching compartment return air duct 50 to the third switching compartment return port 51C.

[0032] 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 relative to 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, relative to 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.

[0033] Air in the temperature switchable compartment 4 flows from the switchable compartment return air duct inlet 52 through either the first branch air duct 50A, the second branch air duct 50B, or the third branch air duct 50C, and then flows into the cooler compartment 23 through either the first switchable compartment return port 51A, the second switchable compartment return port 51B, or the third switchable compartment 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 switchable compartment return air duct inlet and may be configured independently of one another. Note that it is sufficient for the switchable compartment return air duct 50 to branch into at least two of the first branch air duct 50A, the second branch air duct 50B, and the third branch air duct 50C.

[0034] The freezer compartment return air duct 60 has a freezer compartment return air duct inlet 62 that opens into the freezer compartment 5. The freezer compartment return air duct inlet 62 is provided in the freezer compartment 5 away from the outlet of the cool air duct 29. The freezer compartment return air duct inlet 62 may be provided on the inner wall surface on the rear side of the freezer compartment 5. The freezer compartment return air duct 60 has a freezer compartment return port 61 that opens into the front wall 223 of the cooler compartment 23. The freezer compartment return port 61 is provided in the cooler compartment 23 downstream of the refrigerator compartment return port 41 with respect to the air flow direction D1 and facing the cooler 21. The freezer compartment return port 61 is provided in the cooler compartment 23 downstream of the refrigerator compartment return port 41 with respect to the air flow direction D1 and further downstream of the third switchable compartment return port 51C with respect to the air flow direction D1. Air within the freezer compartment 5 flows from the freezer compartment return air duct inlet 62 through the freezer compartment return air duct 60 and into the cooler compartment 23 through the freezer compartment return port 61. The freezer compartment return port 61 corresponds to the second return port.

[0035] Fig. 4 is a rear view showing the structure of the cooler compartment of the refrigerator according to Embodiment 1. With reference to Fig. 4, the arrangement of the refrigerator compartment return port 41, the first switchable compartment return port 51A, the second switchable compartment return port 51B, the third switchable compartment return port 51C, and the freezer compartment return port 61 in the cooler compartment 23 will be described in detail.

[0036] As shown in FIG. 4 , the cooler 21 disposed within the cooler chamber 23 includes a plurality of heat transfer tubes 71 each having a smooth surface and a plurality of thin plate-like fins 214, and a plurality of U-shaped connecting tubes 72. The heat transfer tubes 71 are arranged vertically. For example, eight heat transfer tubes 71 are arranged vertically. Two adjacent heat transfer tubes 71 are connected at their left-right ends by a connecting tube 72, thereby forming a continuous refrigerant tube. Refrigerant flowing through the refrigerant tubes of the cooler 21 flows from a cooler inlet side 73 connected to the lowest heat transfer tube 71 to a cooler outlet side 74 connected to the highest heat transfer tube 71. Because the air flow direction D1 is from below to above the cooler 21, the lowest heat transfer tube 71 is disposed furthest upstream of the plurality of heat transfer tubes 71 relative to the air flow direction D1. The uppermost heat transfer tube 71 is disposed at the most downstream side of 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 from the cooler inlet side 73 through the heat transfer tube 71 located at the most upstream side with respect to the air flow direction D1, and then flows through the heat transfer tubes 71 located gradually downstream to reach the cooler outlet side 74. As the two-phase refrigerant flowing through the cooler 21 progresses from the cooler inlet side 73 to the cooler outlet side 74, it exchanges heat with the air flowing outside the heat transfer tubes 71. As a result, the two-phase refrigerant flows through the heat transfer tubes 71 while the liquid phase of the refrigerant evaporates. Typically, 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.

[0037] The cooler chamber 23 has five regions: a cooler chamber lowermost region 75, a cooler lower region 76, a middle-lower cooler region 77, a middle-upper cooler region 78, and a cooler upper region 79. The cooler chamber lowermost region 75 is a region located below the cooler 21 in the cooler chamber 23 and is a region located on the most upstream side of the cooler chamber 23 with respect to the air flow direction D1. The cooler lower region 76, the middle-lower cooler region 77, the middle-upper cooler region 78, and the cooler upper region 79 are all regions located in the cooler chamber 23 that overlap with the cooler 21. The cooler lower region 76 is located at the lowest, the middle-lower cooler region 77 is located above the cooler lower region 76, and the middle-upper cooler region 78 is located above the middle-lower cooler region 77. The cooler upper region 79 is located at the highest of these four regions. In relation to the air flow direction D1, a lower cooler region 76, a lower middle cooler region 77, an upper middle cooler region 78, and an upper cooler region 79 are arranged in this order from the upstream side.

[0038] The refrigerator compartment return port 41 is provided in the cooler compartment 23 at a position upstream of the cooler 21 with respect to the air flow direction D1, for example, in the cooler compartment lowermost region 75. The freezer compartment return port 61 is provided in the cooler compartment 23 at a position downstream of the refrigerator compartment return port 41 with respect to the air flow direction D1 and facing the cooler 21, for example, in the cooler upper region 79. The multiple switchable compartment return ports are provided in the cooler compartment 23 at positions facing the cooler 21 and different from one another with respect to the air flow direction D1, for example, in the cooler lower region 76, the lower-middle cooler region 77, and the upper-middle cooler region 78. Specifically, the third switchable compartment return port 51C is provided in the upper-middle cooler region 78, the second switchable compartment return port 51B is provided in the lower-middle cooler region 77, and the first switchable compartment return port 51A is provided in the cooler lower region 76.

[0039] Such differences in arrangement change the "heat exchange distance," which is the distance over which heat is exchanged between the air returning from each storage compartment and cooler compartment 23, from when it flows into cooler 21 until it flows out, and changes the heat transfer area where heat is exchanged between the air returning from each storage compartment and cooler 21. Normally, the temperatures inside refrigerator 1 have the following relationship: temperature inside refrigerator compartment 3 > temperature inside temperature switchable compartment 4 > temperature inside freezer compartment 5. For this reason, the "refrigerator compartment return air," which is the air returning from refrigerator compartment 3 to cooler compartment 23, needs to be cooled the most, followed by the "temperature switchable compartment return air," which is the air returning from temperature switchable compartment 4 to cooler compartment 23. It is therefore considered that the amount of cooling of the "freezer compartment return air," which is the air returning from freezer compartment 5 to cooler compartment 23, is minimized.

[0040] By providing the refrigerator compartment return port 41 of the refrigerator compartment return air duct 40 in the cooler compartment lowermost region 75, the refrigerator compartment 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 refrigerator compartment return air and the cooler 21 is maximized, and the heat transfer area between the refrigerator compartment return air and the cooler 21 is also maximized.

[0041] On the other hand, by providing the freezer compartment return port 61 of the freezer compartment return air duct 60 in the cooler upper region 79, the freezer compartment return air passes from the portion between the upstream end and downstream end of the cooler 21 in the air flow direction D1 to the downstream end. Therefore, the heat exchange distance between the freezer compartment return air and the cooler 21 becomes relatively short, and the heat transfer area with the cooler 21 can be reduced. This prevents the freezer compartment return air from being cooled too much by the cooler 21, and by performing the minimum necessary heat exchange, the thermal load on the cooler 21 is reduced.

[0042] Furthermore, the first switchable compartment return port 51A, the second switchable compartment return port 51B, and the third switchable compartment return port 51C of the switchable compartment return air duct 50 are located between the cooler lower region 76 and the cooler upper middle region 78. Therefore, the heat exchange distance between the temperature switchable compartment return air and the cooler 21 is shorter than the heat exchange distance between the refrigerator compartment return air and the cooler 21, but longer than the heat exchange distance between the freezer compartment return air and the cooler 21. This allows the temperature switchable compartment return air to be cooled at a cooling amount between the cooling amount of the refrigerator compartment return air and the cooling amount of the freezer compartment return air in the cooler 21. By optimizing and minimizing the heat exchange amount in this way, the temperature difference between the cooler 21 and the air can be optimized, making it possible to suppress frost formation on the cooler 21.

[0043] The cooler chamber 23 is also provided with a cooler chamber temperature sensor 47, which is a fourth temperature sensor for measuring the cooler chamber temperature. 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.

[0044] FIG. 5 is a cross-sectional schematic diagram showing the structure of the cooler compartment of the refrigerator according to the first embodiment. As shown in FIG. 5 , the multiple fins 214 attached to the cooler 21 in the cooler compartment 23 are each a rectangular parallelepiped plate in a cross section taken along the depth direction of the cooler compartment 23. The multiple fins 214 are arranged such that the longitudinal direction of the cross section taken along the depth direction of the refrigerator 1. The multiple fins 214 are arranged such that the lateral direction of the cross section taken along the depth direction of the refrigerator 1. The multiple fins 214 are stacked in the height direction of the refrigerator 1. When the cooler 21 is housed in the cooler compartment 23, the front faces of the multiple fins 214 face the front wall 223, which is the wall on the front side of the cooler compartment 23. The multiple fins 214 are arranged such that they face the first switching compartment return port 51A, the second switching compartment return port 51B, and the third switching compartment return port 51C formed in the front wall 223 of the cooler compartment 23. Furthermore, the plurality of fins 214 are arranged so that a portion of them faces the freezer chamber return port 61 formed in the front wall 223 of the cooler chamber 23. Furthermore, when the cooler 21 is housed in the cooler chamber 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 chamber 23.

[0045] The fin 214 is disposed in a position facing the first switching chamber return port 51 A. Of the multiple switching chamber return ports, the first switching chamber return port 51 A is located furthest downstream in the air flow direction D1.

[0046] 4 and 5, the refrigerator 1 has a first branch air passage damper 81A, a second branch air passage damper 81B, and a third branch air passage damper 81C as air passage switching devices. The first branch air passage damper 81A is provided in the first branch air passage 50A and is a damper that opens and closes the first switchable chamber return port 51A of the first branch air passage 50A. The second branch air passage damper 81B is provided in the second branch air passage 50B and is a damper that opens and closes the second switchable chamber return port 51B of the second branch air passage 50B. The third branch air passage damper 81C is provided in the third branch air passage 50C and is a damper that opens and closes the third switchable chamber return port 51C of the third branch air passage 50C.

[0047] By opening any one of the first branch air-channel damper 81A, the second branch air-channel damper 81B, or the third branch air-channel damper 81C and closing the remaining two, 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 is opened and the remaining two are closed. This allows switching to any one of the multiple first branch air ducts 50A, the second branch air duct 50B, and the third branch air duct 50C. Furthermore, by closing all of the first branch air-channel damper 81A, the second branch air-channel 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. This blocks the flow of return air through the switching chamber return air duct 50.

[0048] 6 is a block diagram showing an example of the configuration of the refrigerator according to Embodiment 1. As shown in FIG. 6 , the control device 90 is electrically connected to the operation panel 6, the blower 22, the compressor 24, the refrigerator compartment damper 31, the temperature switchable compartment damper 32, the freezer compartment damper 33, the refrigerator compartment temperature sensor 34, the temperature switchable compartment temperature sensor 35, the freezer compartment temperature sensor 36, the first branch air duct damper 81A, the second branch air duct damper 81B, the third branch air duct damper 81C, the defrost heater 45, and the cooler compartment temperature sensor 47, for example, by signal lines. The control device 90 receives, as inputs, the refrigerator compartment temperature measured by the refrigerator compartment temperature sensor 34, the temperature switchable compartment temperature measured by the temperature switchable compartment temperature sensor 35, the freezer compartment temperature measured by the freezer compartment temperature sensor 36, the outside air temperature measured by the outside air temperature sensor 46, and detection signals from the cooler compartment temperature sensor 47, as well as operation signals from the operation unit of the operation panel 6. Based on the input signals, the control device 90 controls the output of the compressor 24, the airflow rate of the blower 22, the opening degree of each damper, and the energization state of the defrost heater 45 in accordance with a pre-stored operating program so that the temperatures of the refrigerator compartment 3, the temperature switchable compartment 4, and the freezer compartment 5 are maintained at their respective set temperatures. Based on the input signals, the control device 90 outputs display signals relating to the temperature of each storage compartment, etc., to the display unit of the operation panel 6.

[0049] Fig. 7 is a functional block diagram related to temperature control by the refrigerator control device 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 appliance control unit 93, and a storage unit 94. The storage unit 94 stores various data and operation programs used for temperature control.

[0050] The control device 90 executes normal operation and defrosting operation. The normal operation is an operation for cooling an object to be cooled in the refrigerator 1. The defrosting operation is an operation for removing frost formed on the cooler 21.

[0051] The temperature setting unit 91 sets the set temperatures of the refrigerator compartment 3, the temperature switchable compartment 4, and the freezer compartment 5 in accordance with operation signals from the operation unit of the operation panel 6. During normal operation, the temperature acquisition unit 92 compares the set temperatures of each storage compartment set by the temperature setting unit 91 with the indoor temperature detected by a temperature sensor provided in each storage compartment, and outputs the comparison result to the equipment 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. The temperature acquisition unit 92 also compares the set temperature of the temperature switchable compartment 4 with the indoor temperature detected by the temperature switchable compartment temperature sensor 35. The temperature acquisition unit 92 also compares the set temperature of the freezer compartment 5 with the indoor temperature detected by the freezer compartment temperature sensor 36. During normal operation, the equipment control unit 93 controls the compressor 24, the blower 22, the refrigerator compartment damper 31, the temperature switching compartment damper 32, the freezer compartment damper 33, and the first branch air duct damper 81A, the second branch air duct damper 81B, and the third branch air duct damper 81C so that the indoor temperatures detected by the temperature sensors provided in each storage compartment become the set temperatures based on the comparison results by the temperature acquisition unit 92. During defrosting operation, the temperature acquisition unit 92 also acquires measurement results from 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 the results to the equipment control unit 93. During defrosting operation, the equipment control unit 93 controls the compressor 24, blower 22, defrost heater 45, refrigerator compartment damper 31, temperature switching compartment damper 32, freezer compartment damper 33, as well as the first branch air duct damper 81A, the second branch air duct damper 81B, and the third branch air duct damper 81C based on the measurement results of each sensor output from the temperature acquisition unit 92.

[0052] The air passages during normal operation will be described in detail. The control device 90 controls the first branch air passage damper 81A, the second branch air passage damper 81B, and the third branch air passage damper 81C to switch between the first branch air passage 50A, the second branch air passage 50B, and the third branch air passage 50C based on the reference temperature of the temperature switchable compartment 4. The set temperature of the temperature switchable compartment 4 set by the temperature setting unit 91 is used as the reference temperature of the temperature switchable compartment 4, and the first branch air passage 50A, the second branch air passage 50B, and the third branch air passage 50C to be switched to are selected based on this set temperature. The memory unit 94 pre-stores data associating the set temperature of the temperature switchable compartment 4 with the branch air passages appropriate for that set temperature, for example. The device control unit 93 references the set temperature of the temperature switchable compartment 4 set by the temperature setting unit 91 and the data stored in the memory unit 94 to select which of the first branch air passage 50A, the second branch air passage 50B, and the third branch air passage 50C to switch to. The device control unit 93 then controls the first branch air-channel damper 81A, the second branch air-channel damper 81B, and the third branch air-channel damper 81C of the air-channel switching device so as to switch to the selected switching compartment return air channel.

[0053] The set temperature of the temperature switchable compartment 4 and the switchable compartment return air duct are associated, for example, as follows: The first branch air duct 50A, the second branch air duct 50B, and the third branch air duct 50C each have a first switchable compartment return port 51A, a second switchable compartment return port 51B, and a third switchable compartment return port 51C, which are located at different positions relative to the air flow direction D1. When the set temperature of the temperature switchable compartment 4 is relatively high, the branch air duct having a switchable compartment return port located further upstream in the air flow direction D1 is associated. When the set temperature of the temperature switchable compartment 4 is relatively low, the branch air duct having a switchable compartment return port located further downstream in the air flow direction D1 is associated. When the set temperature of the temperature switchable compartment 4 is relatively high, it is considered that the amount of cooling required to cool the air returning from the temperature switchable compartment 4 to the cooler compartment 23 increases. Therefore, by having the air returning from the temperature switchable compartment 4 flow into the cooler 21 from a switchable compartment return port located further upstream in the air flow direction D1, a sufficient heat exchange distance in the cooler 21 is ensured, and the necessary cooling can be performed. On the other hand, when the set temperature of the temperature switchable compartment 4 is relatively low, the air returning from the temperature switchable compartment 4 is caused to flow into the cooler 21 from a switchable compartment return port located downstream in the air flow direction D1. This prevents the heat exchange distance in the cooler 21 from being extended more than necessary, and ensures the minimum necessary heat exchange distance, thereby reducing the thermal load on the cooler 21.

[0054] The temperature switchable compartment 4 can be adjusted to three temperature zones and is provided with a first switchable compartment return port 51A, a second switchable compartment return port 51B, and a third switchable compartment return port 51C through which air in the three temperature ranges flows. For example, when the temperature switchable compartment 4 is set to the chilled temperature zone, the first branch air duct 50A having the first switchable compartment return port 51A located most upstream in the air flow direction D1 is selected. When the temperature switchable compartment 4 is set to the supercooled temperature zone, the second branch air duct 50B having the second switchable compartment return port 51B located next most upstream of the first switchable compartment return port 51A in the air flow direction D1 is selected. When the temperature switchable compartment 4 is set to the soft freezing temperature zone, the third branch air duct 50C having the third switchable compartment return port 51C located most downstream in the air flow direction D1 is selected. The heat exchange distance between the temperature switchable compartment 4 return air and the cooler 21 is the longest when the temperature switchable compartment 4 is set to the chilled temperature range, and the heat exchange distance between the temperature switchable compartment return air and the cooler 21 is the next longest when the temperature switchable compartment 4 is set to the supercooled temperature range.The heat exchange distance between the temperature switchable compartment 4 return air and the cooler 21 is the shortest when the temperature switchable compartment 4 is set to the soft freezing temperature range.

[0055] Based on this relationship, the control device 90 switches between the three branch air ducts. For example, when the set temperature of the temperature switchable compartment 4 is in a first temperature zone included in the chilled temperature zone, the control device 90 opens only the first branch air duct damper 81A, opens the first switchable compartment return port 51A, and switches to the first branch air duct 50A. When the set temperature of the temperature switchable compartment 4 is in a second temperature zone included in the supercooled temperature zone, which is lower than the first temperature zone, the control device 90 opens only the second branch air duct damper 81B, opens the second switchable compartment return port 51B, and switches to the second branch air duct 50B. When the set temperature of the temperature switchable compartment 4 is in a third temperature zone included in the soft freezing temperature zone, which is lower than the second temperature zone, the control device 90 opens only the third branch air duct damper 81C, opens the third switchable compartment return port 51C, and switches to the third branch air duct 50C. 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.

[0056] FIG. 8 is a diagram illustrating an example of a hardware configuration of the control device of the refrigerator according to the first embodiment. As illustrated in FIG. 8 , the functions of the control device 90 are realized, for example, as a processing circuit in the hardware configuration. The functions of the control device 90 are realized, for example, by a processor 95 executing a program stored in a memory 96. The functions of the control device 90 may also be realized by multiple processors and multiple memories working together. Some of the functions of the control device 90 may be implemented as electronic circuits, and other parts may be realized using the processor 95 and the memory 96.

[0057] In this way, the refrigerator 1 is configured so that the set temperature of the return air from the temperature switchable compartment 4 can be switched over a wide range from the refrigeration temperature range to the freezing temperature range. The air duct through which the air returns from the temperature switchable compartment 4 to the cooler compartment 23 is switched to a switchable compartment branch air duct having a switchable compartment return port at an appropriate position among the switchable compartment return ports that open at different positions relative to the air flow direction D1, based on the set temperature of the temperature switchable compartment 4. This allows the distance and heat transfer area for heat exchange between the air returning from the temperature switchable compartment 4 to the cooler compartment 23 and the cooler 21 to be appropriately secured, depending on the set temperature of the temperature switchable compartment 4. In this way, the air returning from the temperature switchable compartment 4 to the cooler compartment 23 exchanges heat with the cooler 21 only to the minimum extent necessary, thereby reducing the thermal load on the cooler 21 and, accordingly, the workload of the compressor 24, which together with the cooler 21 constitutes the refrigeration cycle circuit 27.

[0058] Furthermore, all of the switchable compartment return ports of the multiple branch air ducts are disposed downstream of the refrigerator compartment return port 41 and upstream of the freezer compartment return port 61 with respect to the air flow direction D1. With this configuration, the distance over which heat exchange occurs between the air returning from the temperature switchable compartment 4 to the cooler compartment 23 and the cooler 21 can be adjusted to fall within a range between the distance over which heat exchange occurs between the air returning from the refrigerator compartment 3 to the cooler compartment 23 and the cooler 21 and the distance over which heat exchange occurs between the air returning from the freezer compartment 5 to the cooler compartment 23 and the cooler 21. This ensures that the distance over which heat exchange occurs between the air returning from the temperature switchable compartment 4 to the cooler compartment 23 and the cooler 21 corresponds to the temperature range from the refrigeration temperature zone to the freezing temperature zone that can be set in the temperature switchable compartment 4.

[0059] Furthermore, the temperature switchable compartment 4 can be switched between at least three temperature zones: a chilled temperature zone of 0°C or higher but lower than 3°C, a supercooled temperature zone of -3°C or higher but lower than 0°C, and a soft-freezing temperature zone of -10°C or higher but lower than -5°C. This configuration allows the temperature switchable compartment 4 to be used as a chilled compartment, a supercooled storage compartment, or a soft-freezing compartment. For example, when used as a chilled compartment, it can compensate for a lack of capacity in the refrigerator compartment 3, and when used as a supercooled storage compartment, it can preserve fresh foods and the like while maintaining their quality. Furthermore, when used as a soft-freezing compartment, it can freeze and store foods in a manner that allows them to be used immediately. This improves the convenience of the refrigerator 1 for its users.

[0060] Next, we will explain the movement of air in the cooler chamber 23. The cooler chamber 23 receives return air from the refrigerator chamber 3, return air from the temperature switchable chamber 4, and return air from the freezer chamber 5.

[0061] The refrigerator compartment return air is air in the refrigeration temperature range. The refrigerator compartment return air flows into the cooler compartment 23 from a refrigerator compartment return port 41 formed in the front wall 223 of the cooler compartment 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 compartment 23 and reaches the most upstream position of the cooler 21, where it exchanges heat with the cooler 21.

[0062] The temperature switchable compartment return air is air in a temperature range corresponding to the set temperature of the temperature switchable compartment 4, which is set within a range from the refrigeration temperature zone to the freezer temperature zone. By switching to one of the branch air ducts, the temperature switchable compartment return air flows into the cooler compartment 23 from one of a plurality of switchable compartment return ports 51 formed in the front wall 223 of the cooler compartment 23. The plurality of switchable compartment return ports guide the temperature switchable compartment return air in a temperature range closest to the refrigeration temperature zone on the upstream side in the air flow direction D1, and guide the temperature switchable compartment return air in a temperature range closer to the freezer temperature zone as they move downstream in the air flow direction D1.

[0063] When the temperature switchable compartment 4 is set to the temperature range closest to the refrigeration temperature range, the temperature switchable compartment return air flows into the cooler compartment 23 through the first switchable compartment return port 51A formed in the front wall 223 of the cooler compartment 23. An example of a case in which the temperature switchable compartment 4 is set to the temperature range closest to the refrigeration temperature range is when it is set to the chilled temperature range. The temperature switchable compartment return air from the first switchable compartment return port 51A is temperature switchable compartment return air with the highest temperature range. The first switchable compartment return port 51A is located downstream of the refrigerator compartment return port 41 in the air flow direction D1 and is the most upstream of the multiple switchable compartment return ports. The air flowing in through the first switchable compartment return port 51A reaches the fins 214 attached at a position opposite the first switchable compartment return port 51A and exchanges heat with the cooler 21 via the fins 214.

[0064] When the temperature switchable compartment 4 is set to a temperature range intermediate between the refrigeration temperature zone and the freezing temperature zone, the temperature switchable compartment return air flows into the cooler compartment 23 through the second switchable compartment return port 51B. The temperature switchable compartment 4 is set to a temperature range intermediate between the refrigeration temperature zone and the freezing temperature zone, for example, when it is set to the supercooling temperature zone. The second switchable compartment return port 51B is located downstream of the first switchable compartment return port 51A and upstream of the third switchable compartment return port 51C in the air flow direction D1. The air flowing in through the second switchable compartment return port 51B exchanges heat with the cooler 21 via fins 214 attached opposite the second switchable compartment return port 51B.

[0065] When the temperature switchable compartment 4 is set to the temperature range closest to the freezing temperature range, the temperature switchable compartment return air flows into the cooler compartment 23 through the third switchable compartment return port 51C. An example of a case in which the temperature switchable compartment 4 is set to the temperature range closest to the freezing temperature range is when it is set to the soft freezing temperature range. The temperature switchable compartment return air from the third switchable compartment return port 51C is temperature switchable compartment return air in the lowest temperature range. The third switchable compartment return port 51C is downstream of the second switchable compartment return port 51B in the air flow direction D1 and is located furthest downstream in the air flow direction D1 among the multiple switchable compartment return ports. The air flowing in through the third switchable compartment return port 51C exchanges heat with the cooler 21 via fins 214 attached in a position opposite the third switchable compartment return port 51C.

[0066] The freezer compartment return air is air in the freezing temperature range. The freezer compartment return air flows into the cooler compartment 23 from a freezer compartment return port 61 formed in the front wall 223 of the cooler compartment 23 and located at the most downstream side of the cooler 21 in the air flow direction D1. The air flowing in from the freezer compartment return port 61 reaches fins 214 provided at a position opposite the freezer compartment return port 61, and exchanges heat with the cooler 21 via the fins 214.

[0067] The air introduced from the refrigerator compartment return port 41, the first switchable compartment return port 51A, and the second switchable compartment return port 51B is the temperature-switchable compartment return air having a relatively high temperature range. The air introduced from the third switchable compartment return port 51C and the freezer compartment return port 61 is the temperature-switchable compartment return air having a relatively low temperature range. The temperature difference between the temperature-switchable compartment return air having a relatively high temperature range and the cooler 21 that exchanges heat with this air is greater than the temperature difference between the temperature-switchable compartment return air having a relatively low temperature range and the cooler 21 that exchanges heat with this air. On the other hand, the temperature difference between the temperature-switchable compartment return air having a relatively low temperature range and the cooler 21 that exchanges heat with this air is smaller than the temperature difference between the temperature-switchable compartment return air having a relatively high temperature range and the cooler 21.

[0068] Although the control device 90 controls the air-channel switching device based on a set temperature as the reference temperature of the temperature switchable compartment 4, this is not limiting. The reference temperature of the temperature switchable compartment 4 may be the measured indoor temperature of the temperature switchable compartment 4. For example, the control device 90 may control the air-channel switching device based on the indoor temperature detected by the temperature switchable compartment temperature sensor 35, which detects the temperature inside the temperature switchable compartment 4. With this configuration, when the temperature switchable compartment 4 is opened and outside air flows in, causing a significant rise in the indoor temperature, the branch air channels can be switched in accordance with the rise in temperature. Furthermore, heat exchange between the temperature switchable compartment return air and the cooler 21 can be performed with a cooling amount corresponding to the rise in temperature. Furthermore, the reference temperature of the temperature switchable compartment 4 may be, for example, the average value of the set temperature of the temperature switchable compartment 4 and the measured indoor temperature. The reference temperature of the temperature switchable compartment 4 may be based on at least one of the set temperature of the temperature switchable compartment 4 and the measured indoor temperature.

[0069] Furthermore, although the number of temperature zones adjusted in the temperature switchable compartment 4 and the number of branch air ducts are the same in the above description, this is not particularly limited. For example, the number of temperature zones adjusted in the temperature switchable compartment 4 may be three, and the number of branch air ducts may be two. In this case, as an example, when the temperature zone of the temperature switchable compartment 4 is either the chilled temperature zone or the supercooled temperature zone, the cooler compartment 23 may be switched to a branch air duct having a switchable compartment return port located upstream in the air flow direction D1. Furthermore, when the temperature zone of the temperature switchable compartment 4 is the soft freezing temperature zone, the cooler compartment 23 may be switched to a branch air duct having a switchable compartment return port located downstream in the air flow direction D1.

[0070] (Overall Cooling Control) Next, a description will be given of cooling operation control performed by the control device 90 in the refrigerator 1 according to the present embodiment 1. Fig. 9 is a timing chart showing the overall cooling control of the refrigerator according to the present embodiment 1. Specifically, Fig. 9 shows a timing chart of cooling control in the refrigerator 1 during each operation period of pre-defrost operation, defrost operation, and post-defrost operation.

[0071] The cooling control performed by the control device 90 on the refrigerator 1 is roughly classified into four types of control. The four types of control are (1) normal cooling control, (2) cooling control before defrosting operation, (3) defrosting operation control, and (4) cooling control after defrosting operation (the first cooling control performed after defrosting operation). In FIG. 9 , period RBP is the period during which cooling control before defrosting operation is performed. Period RDP is the period during which defrosting operation control is performed. Period RAP is the period during which cooling control after defrosting operation is performed. Period RNP is the period during which normal cooling control is performed. The refrigerator 1 according to the first embodiment is mainly characterized by (4) cooling control after defrosting operation. The following describes how the cooling control after defrosting operation in the refrigerator 1 according to the first embodiment can improve energy conservation.

[0072] FIG. 10 is a flowchart showing the overall cooling control of the refrigerator according to the first embodiment. With reference to FIG. 10, the overall flow of cooling operation control performed by the control device 90 will be described. The flowchart shown in FIG. 10 starts in step S1 from a state in which the control device 10 is performing normal cooling control on the refrigerator 1. In step S2, the control device 90 determines whether or not a condition for terminating the normal cooling control is satisfied. If the result of the determination in step S2 is that the condition for terminating the normal cooling control is not satisfied (step S2: No), the control device 90 returns to step S1 and continues the normal cooling control.

[0073] If the condition for terminating the normal cooling control is satisfied as a result of the determination in step S2 (step S2: Yes), the control device 90 starts the cooling control before the defrosting operation (step S3). In step S4, the control device 90 determines whether the condition for terminating the cooling control before the defrosting operation is satisfied. If the condition for terminating the cooling control before the defrosting operation is not satisfied as a result of the determination in step S4 (step S4: No), the control device 90 returns to step S3 and continues the cooling control before the defrosting operation.

[0074] If the determination result in step S4 indicates that the condition for terminating cooling control before the defrosting operation is satisfied (step S4: Yes), the control device 90 starts the defrosting operation control (step S5). In step S6, the control device 90 determines whether the condition for terminating defrosting operation control is satisfied. If the determination result in step S6 indicates that the condition for terminating defrosting operation control is not satisfied (step S6: No), the control device 90 returns to step S5 and continues the defrosting operation control.

[0075] If the determination result in step S6 indicates that the condition for terminating the defrosting operation control is satisfied (step S6: Yes), the control device 90 starts cooling control after the defrosting operation (step S7). In step S8, the control device 90 determines whether the condition for terminating the cooling control after the defrosting operation is satisfied. If the determination result in step S8 indicates that the condition for terminating the cooling control after the defrosting operation is not satisfied (step S8: No), the control device 90 returns to step S7 and continues the cooling control after the defrosting operation. On the other hand, if the determination result in step S8 indicates that the condition for terminating the cooling control after the defrosting operation is satisfied (step S8: Yes), the control device 90 returns to step S1 and starts normal cooling control.

[0076] In the present embodiment 1, the control device 90 controls the operation of the refrigerator 1 by repeating (1) normal cooling control, (2) cooling control before defrosting operation, (3) defrosting operation control, and (4) cooling control after defrosting operation in the order of (1) → (2) → (3) → (4) → (1) → ... as described above.

[0077] In this way, refrigerator 1 repeats cooling operation and defrosting operation, such as cooling operation → defrosting operation → cooling operation → ..., in order to melt frost adhering to cooler 21 and efficiently cool the object to be cooled. This is the same as in conventional refrigerators. Refrigerators equipped with a cooler and a defrost heater determine whether or not to perform the defrosting operation depending on the type of refrigerator, and periodically perform the defrosting operation.

[0078] (Normal cooling control) Next, the normal cooling control in the refrigerator 1 of the first embodiment will be described. Figs. 11 to 16 are flowcharts showing the operation procedure of the normal cooling control in the refrigerator 1 according to the first embodiment. Fig. 11 shows the first half of the normal cooling control, and Figs. 12 to 16 show the second half of the normal cooling control. Fig. 12 shows the cooling control related to the temperature switchable compartment 4. Fig. 13 shows the cooling control related to the refrigerator compartment 3. Figs. 14 to 16 show the cooling control related to the freezer compartment 5. The flows shown in Figs. 12 to 16 are processed in parallel by the control device 90.

[0079] FIG. 11 is a flowchart showing the first half of the normal cooling control of the refrigerator according to the first embodiment. In step S11, the control device 90 checks the values ​​of various parameters used in the normal cooling control. In step S12, the control device 90 starts monitoring the measurement values ​​of the temperature sensors in each storage compartment used in the normal cooling control. Specifically, the control device 90 acquires from the storage unit 94 a first defrost interval time Limit_time1 that serves as a criterion for a first termination determination of the normal cooling control. The control device 90 acquires from the storage unit 94 a second defrost interval time Limit_time2 that serves as a criterion for a second termination determination of the normal cooling control. The control device 90 starts measuring the defrost interval time interval_time to measure the actual interval time of the defrosting operation.

[0080] The refrigerator 1 according to the first embodiment determines the defrost interval time based on two types of time. The first is a first defrost interval time, which performs a defrost operation when the continuous operation time of the compressor 24 has exceeded a first threshold time. The second is a second defrost interval time, which performs a defrost operation when the number of door opening / closing times of the refrigerator 1 is equal to or greater than a predetermined threshold time and the accumulated operation time since the end of the last defrost operation of the compressor 24 has exceeded a second threshold time.

[0081] The first threshold time of the first defrost interval time differs depending on the specifications of the refrigerator. Therefore, the first threshold time of the first defrost interval time is determined in advance through experiments on the target refrigerator, and is the time when it is considered that frost is likely to form on the cooler 21. The second defrost interval time is the time when the refrigerator door is opened and closed very frequently, it is estimated that a large amount of hot and humid air from outside the refrigerator is contained inside the refrigerator, and it is considered that frost is likely to form on the cooler 21. Here, the number of times the door is opened and closed per day depends on the type of storage compartment and the number of doors of the target refrigerator. For example, when the number of times the door is opened and closed is approximately 60 times per day or more, the control device 90 refers to the second defrost interval time.

[0082] The first defrost interval time and the second defrost interval time also differ depending on the insulation specifications or the size of the cooler of the refrigerator. The first defrost interval time is often set to, for example, 24 to 72 hours. The second defrost interval time is often set to, for example, 12 to 24 hours.

[0083] Returning to the description of steps S11 and S12 shown in Fig. 11, the control device 90 starts monitoring the temperature T_Fth obtained from the freezer compartment temperature sensor 36. The control device 90 obtains the set temperature TF_set of the freezer compartment 5 and the allowable range ±dθf for the set temperature of the freezer compartment 5 from the storage unit 94. The allowable range dθf for the set temperature of the freezer compartment 5 differs depending on the specifications of the refrigerator 1, but is often set in the range of approximately 1°C to 2°C.

[0084] The control device 90, like the freezer compartment 5, acquires various parameters used in the cooling control of the temperature switchable compartment 4 and the refrigerator compartment 3 and monitors the detected values ​​of various sensors. The control device 90 starts monitoring the temperature T_Rth acquired from the refrigerator compartment temperature sensor 34. The control device 90 acquires the set temperature TR_set of the refrigerator compartment 3 and the allowable range ±dθr of the refrigerator compartment 3 from the memory unit 94. The allowable range dθr of the refrigerator compartment 3 differs depending on the specifications of the refrigerator 1, but is often set to a range of approximately 2°C to 3°C.

[0085] The control device 90 begins monitoring the temperature T_Sth obtained from the temperature switchable compartment temperature sensor 35. The control device 90 obtains the set temperature TS_set of the temperature switchable compartment 4 and the allowable range ±dθs of the temperature switchable compartment 4 from the memory unit 94. The allowable range dθs of the temperature switchable compartment 4 varies depending on the specifications of the refrigerator 1, but is often set to a range of approximately 0.3°C to less than 1.0°C. The temperature switchable compartment 4 requires supercooling control, which requires more delicate temperature control than other storage compartments, such as the refrigerator compartment 3 or the freezer compartment 5. Therefore, the allowable range dθs is set to the smallest value among the storage compartments in the refrigerator 1 so that the temperature in the temperature switchable compartment 4 does not fluctuate greatly and can be maintained more uniformly. The control device 90 obtains the set parameter values ​​and sensor detection data for each storage compartment in this way and controls the temperature of each storage compartment so that it falls within the allowable range based on the set temperature.

[0086] In step S13, the control device 90 initializes the count flag DOOR_COUNT, which is a variable that records the number of times the door of the refrigerator 1 is opened and closed. The control device 90 starts measuring the count flag DOOR_COUNT (step S14). At that time, the control device 90 acquires the threshold number of times door_limit, which is the upper limit of the number of times the door of the refrigerator 1 is opened and closed, from the storage unit 94. In step S15, the control device 90 reads the compressor flag CR, which records whether the compressor 24 is operating or stopped, from the storage unit 94, and checks the operating state of the compressor 24. CR=0 means that the compressor 24 is stopped. CR=1 means that the compressor 24 is operating. In step S16, the control device 90 reads the blower flag FR, which records whether the blower 22 is operating or stopped, from the storage unit 94, and checks the operating state of the blower 22. FR=0 means that the blower 22 is stopped. FR=1 means that the blower 22 is operating. Thereafter, the control device 90 performs parallel temperature control for each of the storage compartments, ie, the refrigerator compartment 3, the temperature switchable compartment 4, and the freezer compartment 5.

[0087] Next, the procedure for cooling control for the temperature switchable compartment 4 will be described with reference to FIG. 12 . FIG. 12 is a flowchart showing the operational procedure for cooling control for the temperature switchable compartment 4 in normal cooling control of the refrigerator according to Embodiment 1. The control device 90 starts monitoring the temperature T_Sth received from the temperature switchable compartment temperature sensor 35 (step S21). The control device 90 acquires the set temperature TS_set for the temperature switchable compartment 4 from the storage unit 94 and confirms the current set temperature TS_set (step S22). The control device 90 acquires the allowable range ±dθs for the set temperature of the temperature switchable compartment 4 from the storage unit 94 and confirms the allowable range ±dθs (step S23).

[0088] When the control device 90 checks the set temperature TS_set of the temperature switchable compartment 4, it determines the temperature range of the current set temperature of the temperature switchable compartment 4. Specifically, the control device 90 determines which of the following three temperature ranges the set temperature TS_set of the temperature switchable compartment 4 falls into:

[0089] 1) First temperature range: 0°C≦TS_set 2) Second temperature range: -3°C≦TS_set<0°C 3) Third temperature range: TS_set<-3°C

[0090] The first temperature range is when the set temperature TS_set is equal to or higher than 0° C. The second temperature range is when the set temperature TS_set is equal to or higher than −3° C. and lower than 0° C. The third temperature range is when the set temperature TS_set is lower than −3° C.

[0091] In step S24, the control device 90 switches the open / close state of the return air duct for the temperature switchable compartment 4 depending on the temperature range to which the set temperature TS_set for the temperature switchable compartment 4 belongs. Specifically, if the set temperature TS_set belongs to the first temperature range, the control device 90 opens the first branch air-channel damper 81A and closes the second branch air-channel damper 81B and the third branch air-channel damper 81C. If the set temperature TS_set for the temperature switchable compartment 4 belongs to the second temperature range, the control device 90 closes the first branch air-channel damper 81A and the third branch air-channel damper 81C and opens the second branch air-channel damper 81B. If the set temperature TS_set for the temperature switchable compartment 4 belongs to the third temperature range, the control device 90 closes the first branch air-channel damper 81A and the second branch air-channel damper 81B and opens the third branch air-channel damper 81C.

[0092] By switching the return air duct of the temperature switchable compartment 4 in this manner, the "heat exchange distance," which is the distance over which air returning from the temperature switchable compartment 4 to the cooler compartment 23 exchanges heat from the time it flows into the cooler 21 until it flows out, changes. This changes the heat transfer area where heat is exchanged between the air returning from the temperature switchable compartment 4 and the cooler 21, depending on the temperature setting of the temperature switchable compartment 4. In the switchable compartment return air duct 50 of the temperature switchable compartment 4, the first switchable compartment return port 51A, the second switchable compartment return port 51B, and the third switchable compartment return port 51C are located between the cooler lower region 76 and the cooler upper middle region 78. Therefore, the heat exchange distance from the temperature switchable compartment 4 to the cooler 21 is shorter than the heat exchange distance from the refrigerator compartment 3 to the cooler 21 and longer than the heat exchange distance from the freezer compartment 5 to the cooler 21. This allows the temperature switchable compartment return air to be cooled by an amount between the amount of cooling of the refrigerator compartment return air and the amount of cooling of the freezer compartment return air in the cooler 21. By optimizing and minimizing the amount of heat exchange in this way, the temperature difference between the cooler 21 and the air can also be optimized, preventing the return air from the temperature-switchable chamber 4 from being excessively cooled by the cooler 21. By performing the minimum amount of heat exchange necessary, the thermal load on the cooler 21 can be reduced, and energy-saving performance can be improved.

[0093] After determining the air passage based on the set temperature of the temperature switchable compartment 4 in step S24, the control device 90 determines whether the condition T_Sth≧TS_set+dθs is satisfied (step S25). If the condition of step S25 is not satisfied (step S25: No), the control device 90 closes the temperature switchable compartment damper 32 if it is open, and maintains the temperature switchable compartment damper 32 closed if it is closed (step S26). The control device 90 then returns to the processing of step S25. On the other hand, if the condition of step S25 is satisfied (step S25: Yes), the control device 90 opens the temperature switchable compartment damper 32 (step S27). In other words, the control device 90 maintains the temperature switchable compartment damper 32 closed until the condition T_Sth≧TS_set+dθs is satisfied.

[0094] After opening the temperature-switchable compartment damper 32 in step S27, the control device 90 determines whether the condition T_Sth<TS_set-dθs is satisfied (step S28). If the condition of step S28 is not satisfied (step S28: No), the control device 90 repeats the process of step S28 until the condition of step S28 is satisfied. On the other hand, if the condition of step S28 is satisfied (step S28: Yes), the control device 90 switches the temperature-switchable compartment damper 32 to the closed state (step S29). Then, the control device 90 returns to the process of step S25.

[0095] As described above, the control device 90 refers to the detected value of the temperature switchable compartment temperature sensor 35 and controls the opening and closing of the temperature switchable compartment damper 32 so that the temperature T_Sth of the temperature switchable compartment 4 falls within the allowable range ±dθs with the set temperature TS_set as the target value, according to the flow shown in Figure 12. By controlling the opening and closing of the temperature switchable compartment damper 32 by the control device 90, the cooling air flow to the temperature switchable compartment 4 is adjusted, and the temperature of the object to be cooled is maintained at the set temperature TS_set.

[0096] Next, a procedure for cooling control of refrigerator compartment 3 will be described with reference to Fig. 13 . Fig. 13 is a flowchart showing an operation procedure for cooling control of the refrigerator compartment in normal cooling control of the refrigerator according to Embodiment 1. Control device 90 starts monitoring temperature T_Rth received from refrigerator compartment temperature sensor 34 (step S31). Control device 90 acquires set temperature TR_set of refrigerator compartment 3 from memory unit 94 and confirms set temperature TR_set (step S32). Control device 90 acquires allowable range ±dθr of the set temperature of refrigerator compartment 3 from memory unit 94 and confirms allowable range ±dθr (step S33).

[0097] Then, the control device 90 determines whether the condition T_Rth≧TR_set+dθr is satisfied (step S34). If the condition of step S34 is not satisfied (step S34: No), the control device 90 switches the refrigerator compartment damper 31 to the closed state if it is in the open state, and maintains the refrigerator compartment damper 31 in the closed state if it is in the closed state (step S35). The control device 90 then returns to the processing of step S34. On the other hand, if the condition of step S34 is satisfied (step S34: Yes), the control device 90 switches the refrigerator compartment damper 31 to the open state (step S36). In other words, the control device 90 maintains the refrigerator compartment damper 31 in the closed state until the condition T_Rth≧TR_set+dθr is satisfied.

[0098] After opening the refrigerator compartment damper 31 in step S36, the control device 90 determines whether the condition T_Rth<TR_set-dθr is satisfied (step S37). If the condition of step S37 is not satisfied (step S37: No), the control device 90 repeats the process of step S37 until the condition of step S37 is satisfied. On the other hand, if the condition of step S37 is satisfied (step S37: Yes), the control device 90 switches the refrigerator compartment damper 31 to the closed state (step S38). Then, the control device 90 returns to the process of step S34.

[0099] As described above, the control device 90 refers to the detection value of the refrigerator compartment temperature sensor 34 and controls the opening and closing of the refrigerator compartment damper 31 so that the temperature T_Rth of the refrigerator compartment 3 falls within the allowable range ±dθr with the set temperature TR_set as the target value, according to the flow shown in Fig. 13. By controlling the opening and closing of the refrigerator compartment damper 31 by the control device 90, the cooling air to the refrigerator compartment 3 is adjusted and the temperature of the object to be cooled is maintained at the set temperature TR_set.

[0100] Next, a procedure for cooling control for freezing compartment 5 will be described with reference to Fig. 14 to Fig. 16. Fig. 14 to Fig. 16 are flowcharts showing an operation procedure for cooling control for the freezing compartment in the normal cooling control of the refrigerator according to the first embodiment.

[0101] In step S41, the control device 90 determines whether the condition T_Fth≧TF_set+dθf is satisfied. If the condition in step S41 is not satisfied (step S41: No), the control device 90 proceeds to processing in step S45. If the condition in step S41 is satisfied (step S41: Yes), the control device 90 starts the compressor 24 and changes the compressor flag CR to CR=1 (step S42). The control device 90 also starts the blower 22 and changes the blower flag FR to FR=1 (step S43). Then, the control device 90 switches the freezer compartment damper 33 to an open state (step S44) and starts cooling the inside of the freezer compartment 5. Thereafter, the control device 90 proceeds to processing in step S45.

[0102] In step S45, the control device 90 determines whether the condition T_Fth<TF_set-dθf is satisfied (step S45). If the condition of step S45 is not satisfied (step S45: No), the control device 90 returns to the process of step S41 and continues temperature control of the freezer compartment 5. If the condition of step S45 is satisfied (step S45: Yes), the control device 90 stops the compressor 24 and changes the compressor flag CR to CR=0 (step S46). The control device 90 also stops the blower 22 and changes the blower flag FR to FR=0 (step S47). The control device 90 then switches the freezer compartment damper 33 to a closed state (step S48) and temporarily terminates cooling of the interior of the freezer compartment 5. The control device 90 then proceeds to the process of step S49 and determines whether to terminate normal cooling control.

[0103] After step S48, the control device 90 determines which of two types of defrosting time periods to apply as the defrosting interval time period that serves as the termination determination threshold in order to determine the termination of normal cooling control. The two types of defrosting time periods are a first defrosting interval time period with a first threshold time period and a second defrosting interval time period with a second threshold time period. In step S49, the control device 90 checks the opening / closing count flag DOOR_COUNT, which is a flag that counts the number of times the door of the refrigerator 1 is opened and closed, and determines whether the value is greater than the threshold number of times door_limit, which is the upper limit of the number of times the door is opened and closed in the refrigerator 1.

[0104] If the determination result of step S49 is DOOR_COUNT≦door_limit (step S49: No), the control device 90 determines that the number of door opening and closing operations is less than a predetermined threshold number of opening and closing operations, and proceeds to the processing of step S51 to determine the end of normal cooling control using the first defrost interval time. On the other hand, if the determination result of step S49 is DOOR_COUNT > door_limit (step S49: Yes), the control device 90 determines that the number of door opening and closing operations is greater than the predetermined threshold number of opening and closing operations, and proceeds to the processing of step S50 to determine the end of normal cooling control using the second defrost interval time.

[0105] In step S50, the control device 90 compares the current defrost interval time interval_time with the second defrost interval time limit_time2 and determines whether the condition interval_time ≧ Limit_time2 is satisfied. If the condition of step S50 is not satisfied (step S50: No), the control device 90 proceeds to the processing of step S53 without terminating the normal cooling control and continues the normal cooling control. On the other hand, if the condition of step S50 is satisfied (step S50: Yes), the determination to terminate the normal cooling control is satisfied, and the control device 90 terminates the normal cooling control (step S52).

[0106] In step S51, the control device 90 compares the current defrost interval time interval_time with the first defrost interval time Limit_time1 and determines whether the condition interval_time≧Limit_time1 is satisfied. If the condition of step S51 is not satisfied (step S51: No), the control device 90 proceeds to processing of step S53 without terminating the normal cooling control and continues the normal cooling control. On the other hand, if the condition of step S51 is satisfied (step S51: Yes), the determination to terminate the normal cooling control is satisfied, and the control device 90 terminates the normal cooling control (step S52). After step S52, the control device 90 transitions to cooling control before the defrosting operation (step S3 shown in FIG. 10 ).

[0107] The processes in steps S53 through S58 are performed when the condition for terminating normal cooling control is not satisfied, and the control device 90 continues normal cooling control. In step S53, the control device 90 determines whether the conditions T_Sth≧TS_set+dθs and the compressor flag CR=0 are satisfied. If the condition in step S53 is not satisfied (step S53: No), the control device 90 determines that the temperature of the temperature switchable compartment 4 is within the allowable range and proceeds to step S41. The control device 90 then re-executes the temperature control of the freezer compartment 5 under normal cooling control. If the condition in step S53 is satisfied (step S53: Yes), the control device 90 determines that the temperature of the temperature switchable compartment 4 has fallen outside the allowable range while the compressor 24 is stopped, and switches the temperature switchable compartment damper 32 to the open state to perform cooling control (step S54). The control device 90 then activates the blower 22 and changes the blower flag FR to FR=1 (step S55). With this control, the control device 90 operates the blower 22 while the compressor 24 is stopped, thereby supplying the cold air remaining in the cooler chamber to the temperature-switchable compartment 4 and cooling the temperature-switchable compartment 4.

[0108] In step S56, the control device 90 determines whether the condition T_Sth<TS_set-dθs is satisfied. If the condition in step S56 is not satisfied (step S56: No), the control device 90 determines that the temperature of the temperature switchable compartment 4 is within the allowable range and proceeds to step S41. The control device 90 then re-executes the temperature control of the freezer compartment 5 using normal cooling control. If the condition in step S56 is satisfied (step S56: Yes), the control device 90 determines that the temperature switchable compartment 4 has been sufficiently cooled and switches the temperature switchable compartment damper 32 to the closed state (step S57). The control device 90 then stops the blower 22 and changes the blower flag FR to FR=0 (step S58). After stopping the cooling of the temperature switchable compartment 4 in this manner, the control device 90 proceeds to step S41.

[0109] The reason for cooling the temperature switchable compartment 4 while the compressor 24 is stopped as described above will now be explained. The temperature switchable compartment 4 may require supercooling control, which requires more delicate temperature control than other storage compartments, such as the refrigerator compartment 3 or the freezer compartment 5. This is to prevent large fluctuations and maintain a more uniform temperature in the temperature switchable compartment 4. Assume that the temperature in the freezer compartment 5 falls within the appropriate range and the door to the temperature switchable compartment 4 is opened or closed while the compressor 24 is stopped. In this case, the temperature in the temperature switchable compartment 4 may rise, potentially causing the temperature of the temperature switchable compartment 4 to deviate from the allowable range ±dθs. Therefore, this is done to minimize the temperature fluctuation range in the temperature switchable compartment 4 and keep the temperature of the temperature switchable compartment 4 within the allowable range ±dθs.

[0110] Next, we will explain another reason for cooling the temperature-switchable compartment 4 while the compressor 24 is stopped. This is to reduce the power required to operate the compressor 24 and improve energy-saving performance. While this varies depending on the refrigerator's specifications, when the freezer compartment 5 is cooled to approximately -18°C, the cooler compartment will be approximately -25 to -20°C. Therefore, even when the freezer compartment 5 is sufficiently cooled and the compressor 24 is temporarily stopped, the temperature in the cooler compartment will be relatively low compared to the temperature in the temperature-switchable compartment 4. Therefore, by supplying the cold air remaining in the cooler compartment to the temperature-switchable compartment 4, the temperature in the temperature-switchable compartment 4 can be cooled and the temperature in the temperature-switchable compartment 4 can be lowered. In this way, cooling the temperature-switchable compartment 4 while the compressor 24 is stopped reduces power consumption and maintains a uniform temperature in the temperature-switchable compartment 4. As a result, the quality of temperature management in the temperature-switchable compartment 4 can be maintained and energy-saving performance can be improved.

[0111] Next, referring to FIGS. 17 and 18 , control for cooling the temperature switchable compartment 4 while the compressor 24 is stopped will be described. FIG. 17 is a timing chart showing temperature control of the freezer compartment in an ideal temperature control case in the normal cooling control of the refrigerator according to Embodiment 1. In FIG. 17 , the change in the freezer compartment temperature T_Fth is shown in comparison with the set temperature TF_set. However, the refrigerator compartment temperature T_Rth and the temperature switchable compartment temperature T_Sth also change similarly, and these temperature changes are not shown. Because the freezer compartment 5 is cooled while the compressor 24 is operating, the freezer compartment temperature T_Fth decreases. On the other hand, because the freezer compartment 5 is not cooled while the compressor 24 is stopped, the freezer compartment temperature T_Fth tends to increase. In this way, the operation (ON) and stop (OFF) of the compressor 24 and the blower 22 are synchronized with the temperatures of the freezer compartment 5, the refrigerator compartment 3, and the temperature switchable compartment 4.

[0112] FIG. 18 is a timing chart illustrating a case where the temperature of the temperature switchable compartment exceeds the set temperature while the compressor is stopped during normal cooling control of the refrigerator according to the first embodiment. In the left region of FIG. 18 , the freezer compartment 5 and the temperature switchable compartment 4 are cooled while the compressor 24 is operating, based on the temperature changes in the freezer compartment temperature T_Fth and the temperature switchable compartment temperature T_Sth. On the other hand, in the right region of FIG. 18 , if the temperature switchable compartment temperature T_Sth exceeds the upper limit of the allowable range +dθs while the compressor 24 is stopped, the temperature switchable compartment 4 is cooled by operating the blower 22 and the temperature switchable compartment damper 32 while the compressor 24 is stopped. Controlling the blower 22 and the temperature switchable compartment damper 32 allows the temperature switchable compartment 4 to be cooled even when the compressor 24 is stopped, thereby reducing the power consumption of the compressor 24. In FIG. 18 , the dotted portion of the graph showing the relationship between power and time indicates the amount of power consumption that is reduced.

[0113] (Cooling Control Before Defrosting Operation) Next, a procedure for cooling control before defrosting operation in refrigerator 1 according to the first embodiment will be described. Before defrosting operation using defrost heater 45, refrigerator 1 performs cooling until the refrigerator compartment temperature, temperature switchable compartment temperature, and freezer compartment temperature each become equal to or lower than a certain set temperature range in the cooling control section before defrosting operation. Fig. 19 and Fig. 20 are flowcharts showing the operation procedure for cooling control before defrosting operation in the refrigerator according to the first embodiment.

[0114] When starting cooling control before a defrosting operation, the control device 90 checks the values ​​of various parameters used in cooling control before a defrosting operation (step S71). Specifically, the control device 90 acquires information on the freezer compartment set temperature TF_set and the allowable range ±dθf of the set temperature of freezer compartment 5 from the storage unit 94. The control device 90 acquires information on the refrigerator compartment set temperature TR-set and the allowable range ±dθr of the set temperature of refrigerator compartment 3 from the storage unit 94. The control device 90 acquires information on the temperature switchable compartment set temperature TS_set and the allowable range ±dθs of the set temperature of temperature switchable compartment 4 from the storage unit 94.

[0115] The control device 90 starts monitoring the measured values ​​of the temperature sensors in each storage compartment used in the cooling control before the defrosting operation (step S72). Specifically, the control device 90 starts monitoring the temperature T_Fth received from the freezer compartment temperature sensor 36. The control device 90 starts monitoring the refrigerator compartment temperature T_Rth received from the refrigerator compartment temperature sensor 34. The control device 90 starts monitoring the temperature switchable compartment temperature T_Sth received from the temperature switchable compartment temperature sensor 35.

[0116] Next, the control device 90 acquires information on the compressor flag CR from the storage unit 94 and checks the operating state of the compressor 24 (step S73). Thereafter, the control device 90 acquires information on the blower flag FR from the storage unit 94 and checks the operating state of the blower 22 (step S74). The control device 90 then performs parallel processing of temperature control on each of the storage compartments: the refrigerator compartment 3, the temperature switchable compartment 4, and the freezer compartment 5.

[0117] In step S81, the control device 90 determines whether or not the temperatures of the storage compartments, ie, the refrigerator compartment 3, the temperature switchable compartment 4, and the freezer compartment 5, satisfy the conditions for terminating the cooling control before the defrosting operation. Specifically, the control device 90 determines whether or not the refrigerator compartment temperature T_Rth, the temperature switchable compartment temperature T_Sth, and the freezer compartment temperature T_Fth satisfy all of the following three conditions. The determination condition in step S81 is an AND condition of the following three conditions:

[0118] The three conditions are: TF_set-dθf≦T_Fth≦TF_set, TS_set-dθs≦T_Sth≦TS_set, and TR_set-dθr≦T_Rth≦TR_set In step S81, the control device 90 determines whether or not all of these three conditions are met.

[0119] If the determination result of step S81 indicates that the above three conditions are not met (step S81: No), the control device 90 determines that the interior of each storage compartment has not been cooled and continues cooling control. This is because, during defrosting operation, the temperature of each storage compartment rises until the frost on the surface of the cooler 21 melts. To prevent this temperature rise, each storage compartment must be sufficiently cooled before starting the defrosting operation. Therefore, in step S82, the control device 90 starts the compressor 24 and changes the value of the compressor flag CR to CR = 1. In addition, in step S83, the control device 90 starts the blower 22 and changes the value of the blower flag FR to FR = 1. The control device 90 then opens the freezer compartment damper 33 (step S84) to cool the interior of the freezer compartment 5. After processing step S84, the control device 90 returns to processing step S81.

[0120] On the other hand, if the determination in step S81 indicates that the above three conditions are met (step S81: Yes), the control device 90 terminates the cooling control before the defrosting operation and proceeds to preparation processing for the defrosting operation. Specifically, the control device 90 stops the compressor 24 and changes the compressor flag CR to CR = 0 (step S85). Next, the control device 90 stops the blower 22 and changes the blower flag FR to FR = 0 (step S86). Then, the control device 90 switches the freezer compartment damper 33, the refrigerator compartment damper 31, and the temperature switchable compartment damper 32 from the open state to the closed state (step S87). The control device 90 terminates the cooling control before the defrosting operation (step S88) and proceeds to defrosting operation control (step S5 shown in FIG. 10).

[0121] As described above, the reason for checking whether the temperature of each storage compartment of the refrigerator 1 has been cooled to the set temperature range for each storage compartment before defrosting operation is to minimize temperature increases during defrosting operation. During defrosting operation using the defrost heater 45, the defrost heater 45 is energized inside the refrigerator to intentionally generate heat, which causes the temperature of each storage compartment to rise to a certain extent. If the defrosting operation is performed without checking the temperature of each storage compartment and only based on the determination of frost on the cooler when the temperature in each storage compartment is higher than the set temperature range for each storage compartment, the temperature in each storage compartment will rise further. In this case, there is a possibility that the temperature in each storage compartment will exceed the desired temperature range. Therefore, the control device 90 checks that each storage compartment has been cooled to the target set temperature range at least before performing the defrosting operation.

[0122] (Defrosting Operation Control) Next, a procedure for defrosting operation control in the refrigerator 1 according to the present embodiment 1 will be described. Figures 21 and 22 are flowcharts showing the operation procedure for defrosting operation control in the refrigerator according to the embodiment 1. During the defrosting operation, the refrigerator 1 according to the embodiment 1 changes the end threshold temperature Tdef_end in response to the outside air temperature T_ATth.

[0123] When starting a defrosting operation, the control device 90 acquires information on the initial values ​​of the time interval Δt_DEF and the end threshold temperature Tdef_end from the storage unit 94 (step S91). The time interval Δt_DEF serves as time resolution. The control device 90 starts monitoring the outside air temperature T_ATth received from the outside air temperature sensor 46 (step S92). The control device 90 starts monitoring the cooler compartment temperature Tdef_th received from the cooler compartment temperature sensor 47 (step S93).

[0124] The control device 90 determines whether the end threshold temperature Tdef_end is greater than the outside air temperature T_ATth (step S94). If the end threshold temperature Tdef_end is greater than the outside air temperature T_ATth (step S94: Yes), the control device 90 sets the outside air temperature T_ATth to the end threshold temperature Tdef_end. That is, the control device 90 changes the end threshold temperature Tdef_end to the value of the outside air temperature T_ATth (step S95). On the other hand, if the result of the determination in step S94 is that the end threshold temperature Tdef_end is equal to or less than the outside air temperature T_ATth (step S94: No), the control device 90 does not change the end threshold temperature Tdef_end.

[0125] In step S96, the control device 90 initializes the count flag Count to 0 and initializes the defrost time T_def_time1. The control device 90 starts energizing the defrost heater 45 and starts measuring the defrost time T_def_time1 (step S97). The control device 90 continues energizing the defrost heater 45 until the cooler compartment temperature Tdef_th becomes equal to or higher than the end threshold temperature Tdef_end (steps S97 to S101).

[0126] Specifically, the control device 90 acquires the cooler compartment temperature Tdef_th at time t from the cooler compartment temperature sensor 47 (step S98). The control device 90 determines whether the defrosting time T_def_time1 is equal to or greater than the time interval Δt_DEF (step S99). If the defrosting time T_def_time1 is less than the time interval Δt_DEF (step S99: No), the control device 90 repeats the process until the condition of step S99 is satisfied. If the defrosting time Tdef-time1 is equal to or greater than an integral multiple of the time interval Δt_DEF (step S99: Yes), the control device 90 increments the count flag Count by one (step S100) and determines whether the end threshold temperature Tdef_end is equal to or less than the cooler compartment temperature Tdef_th (step S101). The reason for making the determination at an integer multiple of the time interval Δt_DEF is that by counting the number of determinations, it is possible to determine how many times the determination has been made, and therefore the defrosting time required to energize the defrost heater 45 can be determined each time a defrosting operation is performed. If the end threshold temperature Tdef_end is greater than the cooler compartment temperature Tdef_th (step S101: No), the control device 90 repeats the processes of steps S98 to S101. If the end threshold temperature Tdef_end is equal to or less than the cooler compartment temperature Tdef_th (step S101: Yes), the control device 90 ends the defrosting operation (step S102) and transitions to cooling control after the defrosting operation (step S6 shown in FIG. 10: Yes).

[0127] The time interval Δt_DEF is set as short as possible, such as approximately 1 to 5 seconds. The reason is that shortening the time during which the defrost heater 45 is energized as much as possible improves energy-saving performance. In other words, although the amount of heat from the defrost heater 45 increases the cooler compartment temperature Tdef_th, it is desirable that the amount of heat by which the cooler compartment temperature Tdef_th exceeds the end threshold temperature Tdef_end be as small as possible. This is to prevent the cooler compartment temperature Tdef_th from becoming significantly higher than the end threshold temperature Tdef_end.

[0128] 23 to 25, refrigerator 1 according to the first embodiment will be described in comparison with a conventional refrigerator in which the termination threshold temperature is not varied with reference to the outside air temperature. FIG. 23 is a diagram illustrating the relationship between the electric power input and the cooler compartment temperature during defrosting operation at low outside air temperatures in the conventional refrigerator. FIG. 24 is a diagram illustrating the relationship between the electric power input and the cooler compartment temperature during defrosting operation at low outside air temperatures in the refrigerator according to the first embodiment. FIG. 25 is a diagram comparing the length of heater energization time between the conventional refrigerator and the refrigerator according to the first embodiment. The vertical axis on the left in FIGS. 23 to 25 represents the cooler compartment temperature detected by cooler compartment temperature sensor 47.

[0129] The conventional example shown in Fig. 23 illustrates a case where the outside air temperature is 10°C and the termination threshold temperature is fixed at 16°C. As shown in Fig. 23, during the heater energization period, the gradient of the rise in the cooler room temperature suddenly becomes gentler in periods when the cooler room temperature is around 0°C and in periods when the outside air temperature is around 10°C. During these periods, the gradient of the cooler room temperature is almost flat, and there is almost no temperature rise.

[0130] The gradient of the change in the cooler room temperature over time becomes gentler near 0°C because it takes longer to melt the frost. In other words, since frost absorbs a great deal of heat when it changes phase to 0°C, the heat generated by the defrost heater 45 is absorbed to melt the frost near 0°C, and the heat from the defrost heater 45 does not contribute to an increase in the cooler room temperature. In other words, almost all of the heat from the defrost heater 45 is used to melt the frost.

[0131] Furthermore, the gradient of the change in the cooler compartment temperature over time is gentle at around 10°C because a thermal equilibrium is maintained between the amount of heat (amount of cold air entering) entering the inside of the refrigerator 1, i.e., the cooler compartment 23, and the amount of heat generated by the defrost heater 45. If the end threshold temperature is set higher than the outside air temperature, the temperature inside the cooler compartment 23 needs to be raised above the outside air temperature. If an attempt is made to raise the temperature above the outside air temperature, the amount of heat generated by the defrost heater 45 will be lost to the outside air. In other words, some of the heat generated by the defrost heater 45 leaks out of the refrigerator 1, making it difficult for the cooler compartment temperature to rise.

[0132] In thermal conduction, heat moves from areas with a large amount of heat to areas with a small amount of heat and diffuses, so the temperature always tends to be uniform. Therefore, when the heat quantity of the defrost heater 45 raises the temperature inside the cooler compartment 23 to the outside air temperature, 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 raise the temperature inside the cooler compartment 23, the thermal equilibrium with the outside air side will be disrupted, requiring even more heat, and the heat generated by energizing the defrost heater 45 will not be used effectively. Therefore, in conventional refrigerators with a fixed end threshold temperature, the energy-saving performance may deteriorate depending on the outside air temperature.

[0133] In contrast, in Fig. 24, the termination threshold temperature is changed with reference to the outside air temperature sensor 46. Therefore, as shown in Fig. 24, only when the cooler room temperature is around 0°C during the heater energization period does the temperature change over time suddenly become gentler, with an almost flat slope. As described above, the reason why the slope of the temperature change over time becomes gentle when the defrost detection temperature is around 0°C is because a great deal of heat is absorbed during the phase change of the frost. In other words, this indicates that the amount of heat generated by the defrost heater 45 is being absorbed by melting the frost, rather than by an increase in the cooler room temperature, and that defrosting is progressing.

[0134] On the other hand, as shown in Fig. 24, there is no region where the gradient suddenly becomes gentler except when the heat balance is not achieved and the cooler compartment temperature is around 0° C. Therefore, Fig. 24 shows that the amount of heat supplied from the defrost heater 45 is less likely to leak to the outside air side compared to the conventional example in Fig. 23.

[0135] FIG. 25 shows the waveforms of the cooler room temperature in FIGS. 23 and 24 aligned with the timing at which power supply to the defrost heater 45 is started as the starting point. As shown in FIG. 25 , in the conventional example, when the cooler room temperature becomes equal to or higher than the outside air temperature, the temperature rise slope suddenly becomes gentler, and the heat generation amount of the defrost heater 45 is not used effectively. For this reason, the heater power supply period in the conventional example is longer than the heater power supply period in the first embodiment. On the other hand, in the first embodiment, the end threshold temperature Tdef_end is variable depending on the outside air temperature, so it can be seen that the heat generation amount of the defrost heater 45 is used effectively to defrost the cooler 21. For this reason, the heater power supply period in the first embodiment is shorter than the heater power supply period in the conventional example.

[0136] As described above, according to the present embodiment 1, the termination threshold temperature is variable in accordance with the outside air temperature at which the refrigerator 1 is actually operating. Therefore, in the present embodiment 1, the energization time of the defrost heater 45 in the defrost operation control can be shortened, and the power consumption can be reduced, thereby improving the energy saving performance.

[0137] Although the refrigerator 1 of the first embodiment has been described as being configured to change the termination threshold temperature in response to the outdoor temperature, it is assumed that the refrigerator 1 is generally used indoors. For example, when the refrigerator 1 is used at low temperatures, such as when the outdoor temperature is below 2°C, the termination threshold temperature does not need to be changed in response to the outdoor temperature. This is because, even when the outdoor temperature is close to 0°C, if the termination threshold temperature is changed in response to the outdoor temperature, the defrosting operation may be completed at 0°C, the frost melting temperature, resulting in residual frost. In other words, if the outdoor temperature is somewhat higher than 0°C and the heat supplied from the defrost heater 45 can be effectively used, the frost can be completely melted, thereby improving energy-saving performance. Specifically, the termination threshold temperature may be changed in response to the outdoor temperature only when the outdoor temperature is, for example, 2°C or higher. However, the specific outdoor temperature at which the termination threshold temperature is changed in response to the outdoor temperature may be determined in consideration of the product configuration, the user's usage conditions, and the like. For example, the outdoor temperature may be set to 5°C instead of 2°C.

[0138] Furthermore, if the insulation performance of the refrigerator 1 itself is low, the thermal balance described in the conventional example of Fig. 23 is likely to occur. This is because if the insulation capacity of the refrigerator 1 is high, the heat generated inside the refrigerator 1 by the defrost heater 45 is prevented from leaking into the outside air, i.e., the air outside the refrigerator 1. In other words, the thermal balance is less likely to occur in refrigerators 1 that use high-performance insulation materials such as vacuum insulation materials with high insulation capacity, but is more likely to occur in inexpensive refrigerators 1 that do not use vacuum insulation materials. For this reason, in the first embodiment, vacuum insulation materials may be used as the insulation members of the refrigerator 1.

[0139] (Cooling control after defrosting operation) Next, a description will be given of cooling control that the control device 90 executes after a defrosting operation for the refrigerator 1 according to the present embodiment 1. Fig. 26 is a flowchart showing an operation procedure of the cooling control after a defrosting operation for the refrigerator according to the present embodiment 1.

[0140] In step S6 shown in Fig. 10, the control device 90 determines whether the condition for terminating the defrosting operation control is satisfied. Specifically, the control device 90 determines whether the condition in step S101 shown in Fig. 22 is satisfied. If the condition in step S101 is satisfied (step S101: Yes), the control device 90 terminates the defrosting operation control (step S102) and proceeds to the processing of step S7 shown in Fig. 10.

[0141] When the control device 90 starts the process of step S7 shown in Fig. 10, it starts the first half of the first control of the cooling control after the defrosting operation (step S111 shown in Fig. 26). Subsequently, the control device 90 determines whether or not the condition for ending the first half of the first control is satisfied (step S112). As a result of the determination in step S112, if the condition for ending the first half of the first control is not satisfied (step S112: No), the control device 90 returns to step S111 and continues the first half of the first control.

[0142] If the determination result of step S112 indicates that the condition for ending the first half of the first control is satisfied (step S112: Yes), the control device 90 starts the second half of the first control (step S113). Subsequently, the control device 90 determines whether the condition for ending the second half of the first control is satisfied (step S114). If the condition for ending the second half of the first control is not satisfied (step S114: No), the control device 90 returns to step S113 and continues the second half of the first control.

[0143] The first and second halves of the first control are one continuous control. In the first halve of the first control, the control device 90 activates the compressor 24 and the blower 22. In the first halve of the first control, the control device 90 may gradually increase the rotation speed of the compressor 24 to a high rotation speed, and may gradually increase the rotation speed of the blower 22 from a low rotation speed to a high rotation speed. Meanwhile, in the second halve of the first control, the control device 90 maintains the rotation speeds of the compressor 24 and the blower 22 at constant rotation speeds, while determining whether to start cooling the temperature switchable compartment 4 based on the change over time in the temperature of the freezer compartment 5, which is the first storage compartment, and the set temperature of the temperature switchable compartment 4, which is the second storage compartment.

[0144] If the determination result of step S114 indicates that the condition for ending the second half of the first control is satisfied (step S114: Yes), the control device 90 starts the second control (step S115). Subsequently, the control device 90 determines whether the condition for ending the second control is satisfied (step S116). If the condition for ending the second control is not satisfied (step S116: No), the control device 90 returns to step S115 and continues the second control.

[0145] As a result of the determination in step S116, if the condition for terminating the second control is satisfied (step S116: Yes), the control device 90 starts the third control (step S117). Subsequently, the control device 90 determines whether the condition for terminating the third control is satisfied (step S118). If the condition for terminating the third control is not satisfied (step S118: No), the control device 90 returns to step S117 and continues the third control. On the other hand, as a result of the determination in step S118, if the condition for terminating the third control is satisfied (step S118: Yes), the control device 90 ends the cooling control after the defrosting operation and starts normal cooling control for the refrigerator 1 (step S1 shown in FIG. 10 ).

[0146] FIG. 27 is a pH diagram illustrating the effect of reducing the power consumption of the compressor by cooling control after a defrosting operation of the refrigerator according to the first embodiment. The vertical axis of FIG. 27 represents refrigerant pressure, and the horizontal axis represents specific enthalpy. In the refrigerator 1 according to this embodiment, the control device 90 performs cooling control after a defrosting operation in the following order: the first half of the first control, the second half of the first control, the second control, and the third control, as described above. The control device 90 determines whether or not to start cooling the temperature switchable compartment 4 based on the temperature change over time in the freezer compartment 5 and the set temperature of the temperature switchable compartment 4. This prevents the cooler 21 from bearing the entire heat load generated by the rise in the temperature inside the refrigerator due to the defrosting operation all at once. The control device 90 gradually cools the storage compartments from those with a low heat load to those with a high heat load, thereby reducing the heat load on the cooler 21 during a recovery operation performed after a defrosting operation. Reducing the heat load on the cooler 21 during recovery operation reduces the workload of the compressor 24. This will be described with reference to FIG. 27.

[0147] In the ph diagram of FIG. 27 , the refrigeration cycle of a conventional refrigerator is indicated by a dashed line, and the refrigeration cycle of refrigerator 1 according to the first embodiment is indicated by a solid line. In FIG. 27 , the workload generated in the compression process for the compressor to compress the refrigerant in the conventional refrigerator is represented by Wcomp. It can be seen that the workload of the compressor is reduced by ΔWcomp shown in FIG. 27 in refrigerator 1 according to the first embodiment compared to the conventional refrigerator. According to the first embodiment, the workload of compressor 24 can be reduced by ΔWcomp. As a result, the power consumption required to operate compressor 24 can be suppressed, and energy-saving performance can be improved.

[0148] Fig. 28 is a graph showing a difference in power consumption during cooling control after a defrosting operation between a conventional refrigerator and the refrigerator according to embodiment 1. The vertical axis of Fig. 28 represents power P of the refrigerator, and the horizontal axis represents time t. The change in power P of the conventional refrigerator is indicated by a solid line, and the change in power P of refrigerator 1 according to embodiment 1 is indicated by a dashed line.

[0149] The cooling control after the defrosting operation of the refrigerator 1 of the present embodiment 1 is different from that of the conventional refrigerator. As described with reference to FIG. 26 , the refrigerator 1 of the present embodiment 1 performs the cooling control in the order of the first half of the first control, the second half of the first control, the second control, and the third control. This reduces the thermal load on the cooler 21 more than in the conventional refrigerator. As a result, the workload of the compressor 24 is reduced, and the amount of power consumed when the compressor 24 is operating is reduced. The dashed line portion between the solid line and the dashed line in FIG. 28 represents the amount of power consumed reduced by the present embodiment 1 compared to the conventional refrigerator. In the period RDP, as shown in FIG. 28 , the amount of power consumed in the dashed line portion can be reduced compared to the conventional refrigerator.

[0150] Next, a specific example of the operation procedure of the cooling control after the defrosting operation will be described with reference to Figures 29 to 45. First, the operation of the first half of the first control will be described. Figures 29 to 31 are flowcharts showing an example of the operation procedure of the first half of the first control in step S111 shown in Figure 26.

[0151] When the control device 90 starts the first half of the first control, it acquires from the storage unit 94 the defrosting time T_def_time1 of the defrosting operation performed immediately before (step S201). If the immediately preceding defrosting operation is the current defrosting operation, the control device 90 acquires from the storage unit 94 the previous defrosting time T_def_time0 (step S202). Also in step S202, the control device 90 acquires from the storage unit 94 the time interval Δt1, which functions as time resolution. The control device 90 starts monitoring the outside air temperature T_ATth received from the outside air temperature sensor 46 (step S203). The control device 90 initializes the set value rank SP_COMP1 of the compressor rotation speed in the initial stage after defrosting in the first half of the first control after the defrosting operation, setting SP_COMP1 to 0 (step S204).

[0152] Next, the control device 90 controls the dampers of each storage compartment (step S205). Specifically, the control device 90 closes the refrigerator compartment damper 31, the freezer compartment damper 33, and the temperature switchable compartment damper 32. The control device 90 controls each of the three branch air ducts that are return air duct dampers of the temperature switchable compartment 4 (step S206). Specifically, the control device 90 closes the first branch air duct damper 81A, the second branch air duct damper 81B, and the third branch air duct damper 81C. Thereafter, the control device 90 references the outside air temperature T_ATth and determines to which of a plurality of predetermined outside air temperature ranks the outside air temperature T_ATth belongs (step S207).

[0153] For example, in the first embodiment, the control device 90 determines to which of the following six outdoor temperature ranks the outdoor temperature T_ATth belongs: 1) Outdoor temperature rank 1 (AT_R1): T_ATth<12°C 2) Outdoor temperature rank 2 (AT_R2): 12°C≦T_ATth<18°C 3) Outdoor temperature rank 3 (AT_R3): 18°C≦T_ATth<22°C 4) Outdoor temperature rank 4 (AT_R4): 22°C≦T_ATth<28°C 5) Outdoor temperature rank 5 (AT_R5): 28°C≦T_ATth<36°C 6) Outdoor temperature rank 6 (AT_R6): 36°C≦T_ATth

[0154] Outdoor air temperature rank 1 is when the outdoor air temperature T_ATth is lower than 12°C. Outdoor air temperature rank 2 is when the outdoor air temperature T_ATth is equal to or higher than 12°C and lower than 18°C. Outdoor air temperature rank 3 is when the outdoor air temperature T_ATth is equal to or higher than 18°C ​​and lower than 22°C. Outdoor air temperature rank 4 is when the outdoor air temperature T_ATth is equal to or higher than 22°C and lower than 28°C. Outdoor air temperature rank 5 is when the outdoor air temperature T_ATth is equal to or higher than 28°C and lower than 36°C. Outdoor air temperature rank 6 is when the outdoor air temperature T_ATth is equal to or higher than 36°C.

[0155] Then, the control device 90 refers to the outside air temperature T_ATth, determines the outside air temperature rank to which the outside air temperature T_ATth belongs, and records the determined outside air temperature rank in the storage unit 94 as the outside air temperature rank AT_RANK.

[0156] As with the outside air temperature, the control device 90 determines to which of a plurality of predetermined defrost time ranks the current defrost time T_def_time1 belongs (step S208). For example, in the first embodiment, the control device 90 determines to which rank of the following five defrost time ranks DEFtimeR the defrost time T_def_time1 belongs: 1) DEFtimeR1: T_def_time1≦20 2) DEFtimeR2:20<T_def_time1≦30 3) DEFtimeR3:30<T_def_time1≦40 4) DEFtimeR4:40<T_def_time1≦50 5) DEFtimeR5:50<T_def_time1

[0157] The defrost time rank DEFtimeR1 is the case when the defrost time T_def_time1 is 20 minutes or less. The defrost time rank DEFtimeR2 is the case when the defrost time T_def_time1 is 30 minutes or less but longer than 20 minutes. The defrost time rank DEFtimeR3 is the case when the defrost time T_def_time1 is 40 minutes or less but longer than 50 minutes. The defrost time rank DEFtimeR4 is the case when the defrost time T_def_time1 is 50 minutes or less but longer than 40 minutes. The defrost time rank DEFtimeR5 is the case when the defrost time T_def_time1 is longer than 50 minutes.

[0158] When the control device 90 determines the defrost time rank DEFtimeR to which the defrost time T_def_time1 belongs among the above five defrost time ranks, the control device 90 records the determined defrost time rank DEFtimeR in the storage unit 94 as the defrost time rank DEFtime_RANK.

[0159] As described above, the outside air temperature and the defrost time are classified into ranks in order to determine the rotation speed to be set for the compressor during cooling after the defrosting operation. During the defrosting operation using the defrost heater 45, the defrost heater 45 is energized inside the refrigerator to intentionally generate heat, which also increases the temperature of each storage compartment inside the refrigerator. Therefore, after the defrosting operation, the heat load inside the refrigerator is high, and it is important to cool the refrigerator with an appropriate refrigeration capacity that matches the heat load.

[0160] The thermal load on cooler 21 of refrigerator 1 is a combination of the external thermal load resulting from heat intrusion from outside the refrigerator 1 and the internal thermal load generated inside the refrigerator. During cooling after defrosting operation, control device 90 must roughly calculate the total thermal load, which is the sum of the external thermal load and the internal thermal load, and perform cooling control with an appropriate refrigeration capacity for the thermal load on cooler 21. In refrigerator 1 according to the first embodiment, control device 90 calculates the total thermal load from the outside air temperature of refrigerator 1 and the duration of defrosting operation, and increases the rotation speed of compressor 24 to a value corresponding to the total thermal load.

[0161] Specifically, the control device 90 determines the level of the external heat load from the outside air temperature rank, and determines the level of the internal heat load from the DEFtime rank based on the defrosting time, thereby estimating the refrigeration capacity required for cooling after the defrosting operation. The final refrigeration capacity is determined by a combination of various specifications of the refrigerator 1, such as the insulation specifications, cooler specifications, and compressor specifications. For example, the insulation specifications have a significant impact on the external heat load, the cooler specifications affect the total amount of heat load ultimately applied to the cooler, and the compressor specifications affect the maximum refrigeration capacity. In other words, since the insulation specifications, cooler specifications, and compressor specifications are determined when the refrigerator 1 is designed, the target refrigeration capacity can be determined based on the relationship between the outside air temperature rank and the defrosting time rank DEFtimeR.

[0162] An example of a method for setting the refrigeration capacity based on the relationship between the outside air temperature rank and the defrost time rank DEFtimeR will be described with reference to FIG. 32 . FIG. 32 is a table illustrating an example of a set value of the compressor rotation speed at the start of cooling after a defrosting operation in the refrigerator according to the first embodiment. This table is referred to as a compressor rotation speed set value table. AT_R1 to AT_R5 correspond to outside air temperature rank 1 to outside air temperature rank 6. C_rank1 to C_rank5 indicate ranks of the rotation speed of the compressor 24. The larger the rank number, the larger the rotation speed. C_rank1 corresponds to the rank of the minimum rotation speed. C_rank5 corresponds to the compressor MAX rank to which the maximum rotation speed belongs.

[0163] As shown in Figure 32, the higher the outside air temperature rank, the greater the external heat load, so a higher refrigeration capacity can be obtained by increasing the compressor rotation speed. Also, in Figure 32, similar to the outside air temperature, the higher the DEFtime rank based on the defrosting time, the greater the internal heat load, so a higher refrigeration capacity can be obtained by increasing the compressor rotation speed. While Figure 32 shows the rotation speed rank of the compressor 24 on a scale of 1 to 5, the number of classifications is not limited to that shown in Figure 32. The number of classifications for the compressor rotation speed rank may be more detailed, such as on a scale of 1 to 30.

[0164] Furthermore, the number of classifications for the outdoor air temperature rank and the DEFtime rank based on the defrosting time are not limited to the number shown in Figure 32. These parameters may also be classified more finely, such as into 1 to 30 levels, or more roughly, such as into 1 to 3 levels. Regarding the number of rank classifications, the more detailed the setting, the greater the memory capacity required, so the number of classifications may be determined according to the memory capacity to be used. When starting cooling control after a defrosting operation, the control device 90 determines the initial rotation speed of the compressor 24 by referring to the compressor rotation speed setting value table.

[0165] FIG. 33 is a table illustrating an example of a set value of the rotation speed of the blower at the start of cooling after a defrosting operation in the refrigerator according to Embodiment 1. This table is referred to as a blower rotation speed set value table. In the table illustrated in FIG. 33 , FAN_rank1 to FAN_rank5 indicate ranks of the rotation speed of blower 22. The higher the rank number, the higher the rotation speed. FAN_rank1 corresponds to the rank corresponding to the minimum rotation speed. FAN_rank5 corresponds to the blower MAX rank corresponding to the maximum rotation speed. When starting cooling control after a defrosting operation, control device 90 may determine the rotation speed of blower 22 in the initial stage by referring to the blower rotation speed set value table. Note that FIG. 33 represents the rotation speed ranks of blower 22 on a scale of 1 to 5, but the number of rank classifications is not limited to that illustrated in FIG. 33 .

[0166] Returning to the description of the flows shown in Figures 29 to 31, in step S209 of Figure 30, the control device 90 refers to the compressor rotation speed set value table shown in Figure 32 and sets a set value rank SP_COMP1 for the rotation speed of the compressor 24 in the initial stage after defrosting. As described above, the set value of the rotation speed of the compressor 24 is set in the refrigerator 1 based on the predetermined compressor rotation speed set value table shown in Figure 32. Note that the control device 90 may refer to the blower rotation speed set value table shown in Figure 33 and set a set value rank for the rotation speed of the blower 22 in the initial stage after defrosting.

[0167] Thereafter, the control device 90 initializes a time count t_count, which functions as a flag for measuring time, to t_count = 0 (step S210). The control device 90 initializes a compressor rank C_rank, which is the rank of the current rotation speed of the compressor 24, and a fan rank FAN_rank, which is the rank of the current rotation speed of the blower 22 (step S211). That is, the control device 90 sets the rotation speeds of the compressor 24 and the blower 22 to the lowest rotation speed ranks. Specifically, the control device 90 sets C_rank = 1 and FAN_rank = 1. The control device 90 reads out from the storage unit 94 the compressor MAX rank, which is the maximum rotation speed of the compressor 24, and the blower MAX rank, which is the maximum rotation speed of the blower 22, which are set in advance in the refrigerator 1, and confirms them (step S212). The control device 90 sets the read compressor MAX rank to the compressor MAX rank C_rank_max and sets the read fan MAX rank to the fan MAX rank FAN_rank_max. Next, the control device 90 operates the compressor 24 in accordance with the current compressor rank C_rank (step S213). The control device 90 operates the fan 22 in accordance with the current fan rank FAN_rank (step S214).

[0168] After step S214, the control device 90 determines whether to increase the rotation speeds of the compressor 24 and the blower 22 at a cycle of the time count t_count having a time resolution Δt1. Specifically, the control device 90 compares t_count+Δt1 with a predetermined rank-up determination time ΔT_comp_up and determines whether the condition ΔT_comp_up≦t_count+Δt1 is satisfied (step S215). If the time count is less than the rank-up determination time (step S215: No), the control device 90 repeats the process of step S215 and determines whether time has elapsed. On the other hand, if the control device 90 determines that the time count is equal to or greater than the rank-up determination time (step S215: Yes), the control device 90 proceeds to the process of step S216. The rank-up determination time ΔT_comp_up is determined based on the specifications of the compressor 24. The rank-up determination time ΔT_comp_up is, for example, about 1 to 2 minutes, because the rotation speed of the compressor cannot be increased to a high rotation speed in a short period of time due to restrictions on the compressor structure, and therefore the rotation speed of the compressor must be increased to a high rotation speed gradually.

[0169] In step S216, the control device 90 determines whether the current compressor rank C_rank is smaller than the set value rank SP_COMP1 corresponding to the set rotation speed. If the compressor rank C_rank is smaller than the set value rank SP_COMP1 (step S216: Yes), the control device 90 determines that the rotation speed of the compressor 24 has not reached the set value and increases the compressor rank by one rank (step S217). Next, the control device 90 determines whether the fan rank FAN_rank is smaller than the fan maximum rank FAN_rank_max (step S225). If the control device 90 determines that the fan rank FAN_rank is smaller than the fan maximum rank FAN_rank_max (step S218: Yes), the control device 90 increases the fan rank by one rank (step S219). If the result of the determination in step S218 is that the fan rank FAN_rank has reached the maximum fan rank FAN_rank_max (step S218: No), the control device 90 proceeds to the process of step S220. After step S219, the control device 90 initializes the time count t_count (step S220) and returns to step S215.

[0170] On the other hand, if the result of the determination in step S216 is that the compressor rank C_rank is equal to or greater than the set value rank SP_COMP1 (step S216: No), the control device 90 determines that the rotation speed of the compressor 24 has reached a value equal to or greater than the set value, and ends the first half of the first control. Then, the control device 90 proceeds to the second half of the first control (step S112 shown in FIG. 26: Yes).

[0171] As described above, after the defrosting operation, control device 90 performs the cooling control of the first half of the first control, whereby the rotation speed of compressor 24 can be gradually increased to a higher rotation speed, while the rotation speed of blower 22 can also be gradually increased from a low rotation speed to a high rotation speed. The thermal load for cooling the interior of the refrigerator can be applied to compressor 24 in a stepwise manner, the burden on compressor 24 can be reduced, and energy-saving performance can be improved.

[0172] Next, the second half of the first control will be described. Figures 34 to 36 are flowcharts showing an example of the second half of the first control procedure in step S113 shown in Figure 26.

[0173] When the second half of the first control is initiated, the control device 90 begins monitoring the temperature switchable compartment temperature T_Sth received from the temperature switchable compartment temperature sensor 35 (step S301). The control device 90 begins monitoring the freezer compartment temperature T_Fth received from the freezer compartment temperature sensor 36 (step S302). The control device 90 acquires the set temperature TS_set and time resolution Δt2 of the temperature switchable compartment 4 from the storage unit 94 and confirms these values ​​(step S303). Next, the control device 90 controls the dampers of each storage compartment (step S304). Specifically, the control device 90 opens the freezer compartment damper 33. The control device 90 closes the refrigerator compartment damper 31 and the temperature switchable compartment damper 32. The control device 90 controls each of the three branch air ducts provided in the return air duct of the temperature switchable compartment 4 (step S305). Specifically, the control device 90 closes the first branch air-passage damper 81A, the second branch air-passage damper 81B, and the third branch air-passage damper 81C. The control device 90 initializes the count flag w to w=0 (step S306).

[0174] In step S307, the control device 90 records the value of the freezer compartment temperature T_Fth at time t, which serves as a criterion for determining a temperature change, in Tf1. In step S308, the control device 90 initializes the time count Time_section_2, which serves as a flag for determining the time used to calculate the gradient of the temperature change over time in the latter half of the first control, and begins measuring the time count Time_section_2. The control device 90 then determines whether the time count Time_section_2 is equal to or greater than the time resolution Δt2 (step S309). If the time count Time_section_2 is shorter than the time resolution Δt2 (step S309: No), the control device 90 repeats the process of step S309 to determine whether time has passed.

[0175] If the determination result of step S309 indicates that the time count Time_section_2 is equal to or greater than the time resolution Δt2 (step S309: Yes), the control device 90 records the freezer compartment temperature T_Fth at time (t + Δt2) in Tf2 (step S310). The control device 90 then calculates the gradient df / dt of the temperature change over time of the freezer compartment 5 (step S311). Specifically, the control device 90 calculates df / dt = (Tf2 - Tf1) / Δt2 = ΔTf(w) and records ΔTf(w) in the storage unit 94 as the gradient of the temperature change over time of the freezer compartment 5. The control device 90 then determines whether the gradient df / dt of the temperature change over time of the freezer compartment 5 is less than 0 (step S312). If the gradient df / dt of the temperature change over time is equal to or greater than 0 (step S312: No), the control device 90 returns to the processing of step S307.

[0176] If the result of the determination in step S312 is that the gradient df / dt of the temperature change over time is less than 0 (step S316: Yes), the control device 90 determines whether the count flag w is 0 (step S313). If w=0 (step S313: Yes), the control device 90 increments the count of the count flag w by 1, setting w=w+1 (step S314). Thereafter, the control device 90 returns to the processing of step S307.

[0177] If the result of the determination in step S313 is w≠0 (step S313: No), the control device 90 compares the gradient of the temperature change over time of the freezer compartment 5, df / dt=ΔTf(w), with the previous value ΔTf(w-1). Then, the control device 90 determines whether the condition ΔTf(w)≦ΔTf(w-1) is satisfied (step S315). In other words, the control device 90 determines whether the space in the freezer compartment 5 is tending to be cooled. If the result of the determination in step S315 is ΔTf(w)>ΔTf(w-1) (step S315: No), the control device 90 cannot confirm the cooling trend of the freezer compartment 5 and determines that cooling of the freezer compartment 5 needs to be continued, and proceeds to the processing of step S314.

[0178] If the result of the determination in step S315 is ΔTf(w)≦ΔTf(w−1) (step S315: Yes), the control device 90 determines that the space in the freezer compartment 5 tends to be cooled, and compares the freezer compartment temperature T_Fth with the temperature switchable compartment set temperature TS_set. Then, the control device 90 determines whether the condition T_Fth<TS_set is met (step S316).

[0179] If the determination result of step S316 is T_Fth≧TS_set, the set temperature of the temperature-switchable compartment 4 is equal to or relatively lower than the temperature of the freezer compartment 5. When T_Fth≧TS_set, compared to when T_Fth<TS_set, air with a temperature higher than the set temperature TS_set flows into the temperature-switchable compartment 4 when the temperature-switchable compartment damper 32 switches to the open state. This prevents efficient cooling of the temperature-switchable compartment, increasing the heat load on the cooler 21 in terms of cooling the storage compartment. If the control device 90 starts cooling the temperature-switchable compartment 4 when T_Fth≧TS_set, a relatively greater heat load will be imposed on the temperature-switchable compartment 4, thereby increasing the heat load of the cooling of the freezer compartment 5, which is performed in parallel. Therefore, if T_Fth≧TS_set (step S316: No), the control device 90 determines that cooling of the temperature-switchable compartment 4 cannot be started and proceeds to step S314. As a result, the processes of steps S307 to S316 are repeated.

[0180] If the result of the determination in step S316 is that the temperature T_Fth of freezer compartment 5 is lower than the set temperature TS_set of temperature switchable compartment 4 (step S316: Yes), the controller 90 determines that cooling of temperature switchable compartment 4 may begin, and ends the second half of the first control. Then, the controller 90 transitions to the second control (step S114 in FIG. 26: Yes).

[0181] Next, the operation of the second control will be described. Figures 37 to 40 are flowcharts showing an example of the operation procedure of the second control in step S115 shown in Figure 26.

[0182] When the second control is initiated, the control device 90 begins monitoring the temperature switchable compartment temperature T_Sth received from the temperature switchable compartment temperature sensor 35 (step S401). The control device 90 begins monitoring the freezer compartment temperature T_Fth received from the freezer compartment temperature sensor 36 (step S402). The control device 90 acquires the set temperature TR_set of the refrigerator compartment 3 and the time resolution Δt3 from the storage unit 94 and confirms these values ​​(step S403). The control device 90 reads out from the storage unit 94 the compressor MAX rank of the compressor 24 and the fan MAX rank of the fan 22 that are set in advance in the refrigerator 1 and confirms them (step S404). The control device 90 sets the read-out compressor MAX rank to the compressor MAX rank C_rank_max and sets the read-out fan MAX rank to the fan MAX rank FAN_rank_max. The control device 90 then checks the current compressor rank C_rank and fan rank FAN_rank (step S405). The control device 90 then controls the dampers of the storage compartments (step S406). Specifically, the control device 90 opens the freezer compartment damper 33 and the temperature switchable compartment damper 32. The control device 90 closes the refrigerator compartment damper 31.

[0183] In step S407, the control device 90 controls each of the three branch air ducts provided in the return air duct of the temperature switchable compartment 4 in accordance with the set temperature TS_set of the temperature switchable compartment 4. Specifically, the control device 90 reads the set temperature TS_set of the temperature switchable compartment 4 from the memory unit 94 and determines to which of the following temperature ranges the set temperature TS_set of the temperature switchable compartment 4 belongs: 1) First temperature range: 0°C≦TS_set 2) Second temperature range: −3°C≦TS_set<0°C 3) Third temperature range: TS_set<−3°C

[0184] The first temperature range is when the set temperature TS_set is equal to or higher than 0° C. The second temperature range is when the set temperature TS_set is equal to or higher than −3° C. and lower than 0° C. The third temperature range is when the set temperature TS_set is lower than −3° C.

[0185] The control device 90 controls the switching of the return air duct for the temperature switchable compartment 4 according to the temperature range to which the set temperature TS_set of the temperature switchable compartment 4 belongs. Specifically, when the set temperature TS_set of the temperature switchable compartment 4 belongs to the first temperature range, the control device 90 opens the first branch air-channel damper 81A and closes both the second branch air-channel damper 81B and the third branch air-channel damper 81C. When the set temperature TS_set of the temperature switchable compartment 4 belongs to the second temperature range, the control device 90 closes the first branch air-channel damper 81A and the third branch air-channel damper 81C and opens the second branch air-channel damper 81B. When the set temperature TS_set of the temperature switchable compartment 4 belongs to the third temperature range, the control device 90 closes the first branch air-channel damper 81A and the second branch air-channel damper 81B and opens the third branch air-channel damper 81C.

[0186] After step S407, the control device 90 obtains the allowable range ±dθs of the set temperature of the temperature switchable compartment 4 from the storage unit 94 and checks the value (step S408). The control device 90 initializes the count flags j and k to j = 0 and k = 0 (step S409).

[0187] In step S410, the control device 90 records the temperature T_Fth of the freezer compartment 5 at time t in Tf1. The control device 90 records the temperature T_Sth of the temperature switchable compartment 4 at time t in Ts1 (step S411). In step S412, the control device 90 initializes the time count Time_section_3, which serves as a flag for determining the time used to calculate the gradient of the temperature change over time in the second control. The control device 90 then begins measuring the time count Time_section_3. In step S413, the control device 90 determines whether the time count Time_section_3 is equal to or greater than the time resolution Δt3. If Time_section_3<Δt3 (step S413: No), the control device 90 repeats the process of step S413 to determine whether time has passed.

[0188] If the determination result in step S413 is Time_section_3≧Δt3 (step S413: Yes), the control device 90 records the freezer compartment temperature T_Fth at time (t+Δt3) in Tf2 (step S414). The control device 90 records the temperature switchable compartment temperature T_Sth at time (t+Δt3) in Ts2 (step S415). In step S416, the control device 90 calculates the gradient df / dt of the change in temperature of the freezer compartment 5 over time using the formula df / dt=(Tf2-Tf1) / Δt3=ΔTf(j), and records ΔTf(j) in the storage unit 94. In addition, the control device 90 calculates the gradient ds / dt of the temperature change over time in the temperature switchable compartment 4 using the formula ds / dt = (Ts2 - Ts1) / Δt3 = ΔTs(k), and records ΔTs(k) in the memory unit 94.

[0189] In step S417, the control device 90 determines whether the gradient df / dt of the temperature change over time in the freezer compartment 5 is less than 0. If df / dt is greater than or equal to 0 (step S417: No), the control device 90 estimates that the temperature in the freezer compartment 5 is not cooling and that the current refrigeration capacity is insufficient, and determines that the operation time of the compressor 24 will be extended. Therefore, the control device 90 proceeds to the processing of step S418. In step S418, the control device 90 determines that the refrigeration capacity needs to be increased and determines whether the rotation speed of the compressor 24 can be increased. The control device 90 determines whether the rotation speed of the compressor 24 is lower than the maximum rotation speed. Specifically, the control device 90 determines whether C_rank<C_rank_max. If C_rank<C_rank_max (step S418: Yes), the control device 90 increases the rotation speed rank of the compressor 24 by one (step S419). Thereafter, the control device 90 returns to the process of step S410 and continues cooling the freezer compartment 5 and the temperature switchable compartment 4.

[0190] If the result of the determination in step S418 is C_rank=C_rank_max (step S418: No), the control device 90 determines that the rotation speed of the compressor 24 is already set to the maximum rotation speed, and proceeds to the processing of step S420. In step S420, the control device 90 determines whether the rotation speed of the blower 22 is lower than the maximum rotation speed. Specifically, the control device 90 determines whether FAN_rank<FAN_rank_max. If FAN_rank<FAN_rank_max (step S420: Yes), the control device 90 increases the rotation speed rank of the blower 22 by one (step S421). Thereafter, the control device 90 returns to the processing of step S410. If FAN_rank=FAN_rank_max (step S420: No), the control device 90 returns to the processing of step S410.

[0191] On the other hand, if the result of the determination in step S417 is df / dt<0 (step S417: Yes), the control device 90 determines whether the gradient ds / dt of the time change in the temperature of the temperature switchable compartment 4 is less than 0 (step S422). If ds / dt≧0 (step S422: No), the control device 90 determines whether the temperature of the temperature switchable compartment 4 exceeds the upper limit of the allowable range of the set temperature (step S423). Specifically, the control device 90 determines whether the temperature T_Sth of the temperature switchable compartment 4 satisfies the condition T_Sth>TS_set+dθs. If the condition in step S423 is met (step S423: Yes), the control device 90 determines that the refrigeration capacity is insufficient and proceeds to the processing of step S418. If the condition of step S423 is not satisfied (step S423: No), the control device 90 determines that the compressor 24 and the blower 22 may continue in the current operating state, and proceeds to the process of step S424.

[0192] If the result of the determination in step S422 is ds / dt<0 (step S422: Yes), the control device 90 proceeds to the processing of step S424. In step S424, the control device 90 checks whether both count flags j and k are 0. If j=k=0 (step S424: Yes), the control device 90 proceeds to the processing of step S425. In step S425, the control device 90 increments the counts of the count flags j and j by one, setting j=j+1 and k=k+1. Thereafter, the control device 90 returns to the processing of step S410.

[0193] If the result of the determination in step S424 is that one or both of j and k is not 0 (step S424: No), the control device 90 determines whether the conditions ΔTf(j)≦ΔTf(j-1) and ΔTs(k)≦ΔTs(k-1) are met (step S426). That is, the control device 90 determines whether both the freezer compartment 5 and the temperature switchable compartment 4 are cooling. If the condition in step S426 is not met (step S426: No), the control device 90 cannot confirm a cooling trend in either or both of the freezer compartment 5 and the temperature switchable compartment 4, so it determines that cooling can continue and proceeds to the processing of step S425.

[0194] On the other hand, if the condition of step S426 is satisfied (step S426: Yes), the control device 90 determines that there is a cooling tendency and compares the temperature T_Sth of the temperature switchable compartment 4 with the set temperature TR_set of the refrigerator compartment 3. The control device 90 then determines whether the temperature T_Sth of the temperature switchable compartment 4 is lower than the set temperature TR_set of the refrigerator compartment 3 (step S427). Specifically, the control device 90 determines whether T_Sth<TR_set. If the determination result of step S427 is T_Sth≧TR_set (step S427: No), the set temperature of the refrigerator compartment 3 is equal to or relatively lower than the temperature of the temperature switchable compartment 4. In this case, starting cooling of the refrigerator compartment 3 would impose a relatively greater heat load on the cooler 21 than that of the temperature switchable compartment 4. Therefore, the control device 90 determines that the refrigerator compartment 3 cannot be cooled and proceeds to the processing of step S425. Thereafter, the control device 90 returns to the process of step S410, whereby the processes of steps S410 to S427 are repeated.

[0195] On the other hand, if the result of the determination in step S427 is T_Sth<TR_set (step S425: Yes), the control device 90 determines that it is possible to transition to cooling of the refrigerator compartment 3 and ends the second control. Then, the control device 90 transitions to the third control (step S116 shown in FIG. 26: Yes).

[0196] Next, the operation of the third control will be described. Figures 41 to 45 are flowcharts showing an example of the operation procedure of the third control in step S117 shown in Figure 26.

[0197] When the third control is initiated, the control device 90 begins monitoring the temperature switchable compartment temperature T_Sth received from the temperature switchable compartment temperature sensor 35 (step S501). The control device 90 begins monitoring the freezer compartment temperature T_Fth received from the freezer compartment temperature sensor 36 (step S502). The control device 90 begins monitoring the refrigerator compartment temperature T_Rth received from the refrigerator compartment temperature sensor 34 (step S503). In step S504, the control device 90 checks the values ​​of various parameters. Specifically, the control device 90 obtains the time resolution Δt4 from the storage unit 94 and checks its value. The control device 90 obtains the allowable range ±dθs for the set temperature of temperature switchable compartment 4, the allowable range ±dθr for the set temperature of refrigerator compartment 3, and the allowable range ±dθf for the set temperature of freezer compartment 5 from the storage unit 94 and checks each value. The control device 90 checks the set temperature TR_set of the refrigerator compartment 3, the set temperature TS_set of the temperature switchable compartment 4, and the set temperature TF_set of the freezer compartment 5.

[0198] The control device 90 reads from the storage unit 94 and confirms the compressor MAX rank of the compressor 24 and the fan MAX rank of the fan 22, which are set in advance in the refrigerator 1 (step S505). The control device 90 sets the read compressor MAX rank to the compressor MAX rank C_rank_max and sets the read fan MAX rank to the fan MAX rank FAN_rank_max. The control device 90 then confirms the current compressor rank C_rank and fan rank FAN_rank (step S506). In step S507, the control device 90 controls the dampers of each storage compartment. Specifically, the control device 90 opens the freezer compartment damper 33, the refrigerator compartment damper 31, and the temperature switching compartment damper 32. In step S508 , the controller 90 controls each of the three branch air ducts provided in the return air duct of the temperature switchable compartment 4 in accordance with the set temperature TS_set of the temperature switchable compartment 4 .

[0199] Specifically, the control device 90 reads the set temperature TS_set of the temperature switchable compartment 4 from the storage unit 94 and determines to which of the following temperature ranges the set temperature TS_set of the temperature switchable compartment 4 belongs: 1) First temperature range: 0°C≦TS_set 2) Second temperature range: −3°C≦TS_set<0°C 3) Third temperature range: TS_set<−3°C

[0200] When the set temperature TS_set of the temperature switchable compartment 4 belongs to the first temperature range, the control device 90 opens the first branch air-channel damper 81A and closes both the second branch air-channel damper 81B and the third branch air-channel damper 81C. When the set temperature TS_set of the temperature switchable compartment 4 belongs to the second temperature range, the control device 90 closes the first branch air-channel damper 81A and the third branch air-channel damper 81C and opens the second branch air-channel damper 81B. When the set temperature TS_set of the temperature switchable compartment 4 belongs to the third temperature range, the control device 90 closes the first branch air-channel damper 81A and the second branch air-channel damper 81B and opens the third branch air-channel damper 81C.

[0201] After step S508, the control device 90 initializes count flags p, q, and r, setting p = 0, q = 0, and r = 0 (step S509). In step S510, the control device 90 records the temperatures of each storage compartment at time t. Specifically, the control device 90 records the value of the temperature T_Fth of the freezer compartment 5 at time t in Tf1. The control device 90 records the value of the temperature T-Sth of the temperature switchable compartment 4 at time t in Ts1. The control device 90 records the value of the temperature T_Rth of the refrigerator compartment 3 at time t in Tr1. In step S511, the control device 90 initializes time count Time_section_4, which serves as a flag for determining the time for calculating the gradient of the temperature change over time in the third control. Then, the control device 90 starts measuring time count Time_section_4. In step S512, the control device 90 determines whether the time count Time_section_4 is equal to or greater than the time resolution Δt4. If Time_section_4<Δt4 (step S512: No), the control device 90 repeats the process of step S512 to determine whether time has passed.

[0202] If the determination result in step S512 is Time_section_4≧Δt4 (step S512: Yes), the control device 90 records the temperature of each storage compartment at time (t+Δt4). Specifically, the control device 90 records the temperature T_Fth of the freezer compartment 5 at time (t+Δt4) in Tf2. The control device 90 records the temperature T_Sth of the temperature switchable compartment 4 at time (t+Δt4) in Ts2. The control device 90 records the temperature T_Rth of the refrigerator compartment 3 at time (t+Δt4) in Tr2. In step S514, the control device 90 calculates the slopes df / dt, ds / dt, and dr / dt of the change in temperature over time of each storage compartment. Specifically, the control device 90 calculates the gradient df / dt of the change in temperature over time in the freezer compartment 5 using the formula df / dt = (Tf2 - Tf1) / Δt4 = ΔTf(p) and records ΔTf(p) in the memory unit 94. The control device 90 calculates the gradient ds / dt of the change in temperature over time in the temperature switchable compartment 4 using the formula ds / dt = (Ts2 - Ts1) / Δt4 = ΔTs(q) and records ΔTs(q) in the memory unit 94. The control device 90 calculates the gradient dr / dt of the change in temperature over time in the refrigerator compartment 3 using the formula dr / dt = (Tr2 - Tr1) / Δt4 = ΔTr(r) and records ΔTr(r) in the memory unit 94.

[0203] In step S515, the control device 90 determines whether the gradient df / dt of the temperature change over time in the freezer compartment 5 is less than 0. If df / dt is greater than or equal to 0 (step S515: No), the control device 90 infers that the temperature in the freezer compartment 5 is not cooling and that the current refrigeration capacity is insufficient, and determines that the operating time of the compressor 24 will be extended. Therefore, the control device 90 proceeds to step S516. In step S516, the control device 90 determines that the refrigeration capacity needs to be increased and determines whether the rotation speed of the compressor 24 can be increased. Specifically, the control device 90 determines whether C_rank<C_rank_max. If C_rank<C_rank_max (step S516: Yes), the control device 90 increases the rotation speed rank of the compressor 24 by one (step S517). Thereafter, the control device 90 returns to step S510 and continues cooling each storage compartment.

[0204] If the result of the determination in step S516 is C_rank = C_rank_max (step S516: No), the control device 90 determines that the rotation speed of the compressor 24 is already set to the maximum rotation speed, and proceeds to the processing of step S518. In step S518, the control device 90 determines whether FAN_rank < FAN_rank_max. If FAN_rank < FAN_rank_max (step S518: Yes), the control device 90 increases the rotation speed rank of the blower 22 by one (step S519). Thereafter, the control device 90 returns to the processing of step S510. If FAN_rank = FAN_rank_max (step S518: No), the control device 90 returns to the processing of step S510.

[0205] On the other hand, if the result of the determination in step S515 is df / dt<0 (step S515: Yes), the control device 90 determines whether the gradient of the temperature change over time, ds / dt, in the temperature switchable compartment 4 and the gradient of the temperature change over time, dr / dt, in the refrigerator compartment 3, are each less than 0 (step S520). If one or both of ds / dt≧0 and dr / dt≧0 are satisfied (step S520: No), the control device 90 determines whether the conditions T_Sth>TS_set+dθs and T_Rth>TR_set+dθr are satisfied (step S521). If the conditions in step S521 are satisfied (step S521: Yes), the control device 90 determines that the refrigeration capacity is insufficient and proceeds to the processing of step S516. If the condition of step S521 is not satisfied (step S521: No), the control device 90 determines that the compressor 24 and the blower 22 may continue in the current operating state, and proceeds to the process of step S522.

[0206] If the determination result in step S520 is ds / dt<0 and dr / dt<0 (step S520: Yes), the control device 90 proceeds to processing in step S522. In step S522, the control device 90 checks whether all of the count flags p, q, and r are 0. If p=q=r=0 (step S522: Yes), the control device 90 proceeds to processing in step S523. In step S523, the control device 90 increments the counts of the count flags p, q, and r by one, so that p=p+1, q=q+1, and r=r+1. Thereafter, the control device 90 returns to processing in step S510.

[0207] On the other hand, if the result of the determination in step S522 is that at least one of p, q, and r is not 0 (step S522: No), the control device 90 determines whether the conditions ΔTf(p)≦ΔTf(p-1), ΔTs(q)≦ΔTs(q-1), and ΔTr(r)≦ΔTr(r-1) are satisfied (step S524). In other words, the control device 90 determines whether each storage compartment is cooling. If the condition in step S525 is not satisfied (step S524: No), the control device 90 infers that none of the three storage compartments is cooling, determines that cooling control needs to be continued, and proceeds to the processing of step S523.

[0208] If the condition of step S524 is satisfied (step S524: Yes), the control device 90 determines that a cooling trend is occurring. The control device 90 then compares the temperature T_Sth of the temperature switchable compartment 4 with the upper limit of the allowable range dθs of the set temperature TS_set, and compares the temperature T_Rth of the refrigerator compartment 3 with the upper limit of the allowable range dθr of the set temperature TR_set. The control device 90 then determines whether the conditions T_Sth > TS_set + dθs and T_Rth > TR_set + dθr are satisfied (step S525). If the condition of step S525 is satisfied (step S525: Yes), the control device 90 estimates that the cooling trend of each storage compartment continues, but that one of the storage compartments is not sufficiently cooled. Therefore, the control device 90 proceeds to the processing of step S523 to continue cooling at the current refrigeration capacity.

[0209] On the other hand, if the condition of step S525 is not satisfied (step S525: No), the control device 90 determines that the temperatures of the refrigerator compartment 3 and the temperature switchable compartment 4 are within the allowable range of the set temperature and therefore that each storage compartment is cooling. Then, the control device 90 determines whether the condition T_Fth≦TF_set−dθf is satisfied (step S526). The condition T_Fth≦TF_set−dθf is a condition for determining whether to end the third control.

[0210] If the condition of step S526 is not satisfied (step S526: No), although each storage compartment is cooling, the control device 90 determines that the refrigeration capacity is excessive and proceeds to the process of step S527 in order to reduce the refrigeration capacity. In step S527, the control device 90 determines whether the rotation speed of the compressor 24 is the minimum rotation speed. Specifically, the control device 90 determines whether C_rank = 1. If C_rank ≠ 1 (step S527: No), the control device 90 reduces the rotation speed rank of the compressor 24 by one (step S528). Thereafter, the control device returns to the process of step S509. Then, in step S509, the control device 90 initializes each count flag p, q, and r, and then proceeds to the process of step S510 to continue cooling each storage compartment.

[0211] If the result of the determination in step S527 is C_rank = 1 (step S527: Yes), the refrigeration capacity cannot be reduced by lowering the rotation speed of the compressor 24. Therefore, the control device 90 determines whether the rotation speed of the blower 22 is the minimum rotation speed (step S529). Specifically, the control device 90 determines whether FAN_rank = 1. If FAN_rank ≠ 1 (step S529: No), the control device 90 lowers the rotation speed rank of the blower 22 by one (step S530). Thereafter, the control device 90 returns to the processing of step S509. If the result of the determination in step S529 is FAN_rank = 1 (step S529: Yes), the rotation speed of the blower 22 cannot be reduced. Therefore, the control device 90 proceeds to the processing of step S509.

[0212] Here, the reason why the control device 90 proceeds to step S509 and initializes the count flags p, q, and r after steps S528 and S530 will be explained. Reducing the rotation speed of the compressor 24 or the blower 22 reduces the refrigeration capacity. If the control device 90 proceeds to step S510 and subsequent steps without initializing the count flags after reducing the refrigeration capacity, the gradient of the temperature change over time in each storage compartment will be compared with the values ​​before and after the process of reducing the refrigeration capacity. In other words, the control device 90 will be unable to calculate the gradient of the temperature change over time in each storage compartment under different refrigeration capacities and accurately determine the cooling trend. Therefore, by initializing the count flags after the control device 90 reduces the refrigeration capacity by reducing the rotation speed of one or both of the compressor 24 and the blower 22, the cooling trend can be accurately determined.

[0213] If the condition of step S526 shown in FIG. 44 is satisfied (step S526: Yes), the control device 90 determines that the temperature of the freezer compartment 5 has dropped to the target temperature. If the condition of step S526 is satisfied, it can be determined that the set temperatures of all storage compartments, including the freezer compartment 5, the temperature switchable compartment 4, and the refrigerator compartment 3, are within the allowable range. Therefore, the control device 90 terminates the third control (step S118 shown in FIG. 26: Yes). The control device 90 terminates the cooling control after the defrosting operation (step S8 shown in FIG. 10: Yes) and transitions to the normal cooling control of step S1 shown in FIG. 10.

[0214] In this manner, the refrigerator 1 of the first embodiment sequentially executes the first control, the second control, and the third control after the defrosting operation. According to the first embodiment, after the defrosting operation, the first control cools the first storage compartment. When the gradient of the temperature change over time in the first storage compartment is negative and the temperature of the first storage compartment is lower than the set temperature of the second storage compartment, cooling of the second storage compartment also starts. After the first storage compartment, which has a lower set temperature, is sufficiently cooled to accommodate the thermal load generated in the refrigerator due to the defrosting operation, cooling of the second storage compartment, which has a higher set temperature than the first storage compartment, is started. This allows the storage compartments with lower thermal loads to be cooled in stages, starting with the storage compartments with higher thermal loads, and thus reduces the thermal load on the cooler 21, without simultaneously imposing the entire thermal load generated by the rise in the internal temperature of the refrigerator 1 due to the defrosting operation on the cooler 21. By reducing the thermal load on the cooler 21 after the defrosting operation, the amount of power consumption required by the compressor 24 can be reduced. As a result, energy-saving performance can be improved.

[0215] 46 to 48 are diagrams showing example timing charts illustrating cooling control operations after a defrosting operation in the refrigerator according to Embodiment 1. In FIGS. 46 to 48, the horizontal axis represents time t. Period RA1P1 indicates the first half of the first control period. Period RA1P2 indicates the second half of the first control period. Period RA2P indicates the second control period. Period RA3P indicates the third control period.

[0216] 46 to 48 show conceptual diagrams of the case where cooling control after a defrosting operation is divided into first to third controls, and the shift-up and shift-down states of the compressor rotation speed in the control flowcharts described above will be explained. Fig. 46 shows a case where the refrigerator 1 ideally performs cooling control after a defrosting operation without changing the rotation speeds of the compressor 24 and the blower 22.

[0217] In FIG. 46 , in the first half of the first control, while the rotation speed of the compressor 24 is gradually increasing, the temperatures of the freezer compartment 5, the temperature switchable compartment 4, and the refrigerator compartment 3 are all rising. When the first control shifts to the second half, the rotation speed of the compressor 24 is high enough to produce the target refrigeration capacity, and only the freezer compartment 5 is cooled, causing the temperature of the freezer compartment 5 to drop. When the second control shifts to the second control, both the freezer compartment 5 and the temperature switchable compartment 4 are cooled, and the absolute value of the gradient of the temperature change in the freezer compartment 5 is smaller than in the second half of the first control. In other words, the cooling speed in the second control is slower than in the second half of the first control. Then, when the third control shifts to the third control, the freezer compartment 5, the temperature switchable compartment 4, and the refrigerator compartment 3 are cooled, causing the absolute value of the gradient of the temperature change in the freezer compartment 5 and the temperature switchable compartment 4 to be smaller than in the second control. In other words, the cooling speed in the third control is slower than in the second control.

[0218] FIG. 47 shows an example in which the refrigerator 1 increases the rotation speed rank of the compressor 24 or the blower 22 in the second and third cooling control modes after a defrosting operation. Unlike the case shown in FIG. 46 , FIG. 47 shows a case in which the refrigeration capacity is insufficient at the compressor rotation speed set in the initial stage of the cooling control mode after a defrosting operation, and the refrigeration capacity is increased in the second and third control modes. As shown in FIG. 47 , when the control device 90 shifts from the first control mode to the second control mode and starts cooling two storage compartments, the freezer compartment 5 and the temperature switchable compartment 4, the slope of the temperature change in the freezer compartment 5 changes from negative to positive, and the temperature in the freezer compartment 5 tends to rise. Therefore, the control device 90 determines that the refrigeration capacity is insufficient during the second control mode and increases the rotation speed rank of the compressor 24 by one level. Furthermore, when the control device 90 shifts from the second control mode to the third control mode and starts cooling the storage compartments, the freezer compartment 5, the temperature switchable compartment 4, and the refrigerator compartment 3, the temperature in the freezer compartment 5 tends to rise again. Therefore, the control device 90 determines that the refrigeration capacity needs to be increased, and increases the rotation speed rank of the compressor 24 by one.

[0219] When a heat load greater than the estimated heat load is applied to cooler 21, the refrigeration capacity is insufficient at the preset compressor rotation speed, and continuing the cooling operation with the insufficient refrigeration capacity would result in a longer operating time for compressor 24. Therefore, control device 90 increases the refrigeration capacity by increasing the rotation speed of compressor 24. In this way, improving the cooling capacity inside the refrigerator reduces the operating time of the compressor itself, and reduces the amount of power consumed by the overall cooling control of refrigerator 1.

[0220] FIG. 48 shows an example of a case where the refrigerator 1 reduces the rotation speed rank of the compressor 24 or the blower 22 in the second control and the third control of the cooling control after a defrosting operation. Unlike the case of FIG. 46 , FIG. 48 shows a case where the refrigeration capacity is excessive at the compressor rotation speed set in the initial stage of the cooling control after a defrosting operation, and the refrigeration capacity is reduced in the third control. As shown in FIG. 48 , when the control device 90 shifts from the second control to the third control and starts cooling the storage compartments of the freezer compartment 5, the temperature switchable compartment 4, and the refrigerator compartment 3, no temperature rise occurs in the storage compartments, and a cooling trend can be confirmed. Therefore, in the third control, the control device 90 reduces the rotation speed rank of the compressor 24 by one and maintains the reduced state of the compressor 24 rotation speed until the third control ends.

[0221] When a heat load smaller than a predetermined estimated heat load is applied to the cooler 21, the refrigeration capacity becomes excessive at a preset compressor rotation speed, so the refrigeration capacity can be suppressed by reducing the compressor rotation speed. Therefore, the amount of work required to operate the compressor 24 can be suppressed compared to when cooling control is continued while maintaining the compressor rotation speed at the set rotation speed, thereby improving energy conservation.

[0222] As described above, the refrigerator according to the first embodiment performs cooling after a defrosting operation in the order of the first half of the first control, the second half of the first control, the second control, and the third control. This prevents the heat load generated by the rise in the inside temperature during the defrosting operation from being borne by cooler 21 all at once, and allows for stepwise cooling from storage compartments with smaller heat loads to storage compartments with larger heat loads, thereby reducing the heat load on cooler 21. Reducing the heat load on cooler 21 during cooling of the inside of the refrigerator after a defrosting operation reduces the amount of power consumption required by compressor 24. As a result, energy-saving performance can be improved.

[0223] In recent years, with changes in lifestyles due to factors such as an increase in dual-income households and single-person households, there has been a growing tendency for people to buy large amounts of food at once and store them in refrigerators. Therefore, there is a demand for refrigerators with larger capacities and refrigerators that can precisely adjust temperatures to store food at temperatures appropriate for each food. One refrigerator that meets this demand is one that has a temperature-switchable compartment, separate from a refrigerator compartment and a freezer compartment, that can switch the temperature setting from the freezer compartment to the vegetable compartment, as in the refrigerator 1 described in the first embodiment. Furthermore, with social demand for sustainable home appliances, there is a demand for refrigerators with higher energy-saving performance that can accommodate changes in each user's lifestyle.

[0224] Refrigerators with temperature-switchable compartments have a configuration in which the set temperature of the temperature-switchable compartment can be switched over a wide range from the freezing temperature range to the refrigerating temperature range. Therefore, the temperature difference between the air returning from the temperature-switchable compartment and the surface of the cooler that performs heat exchange varies depending on the temperature inside the temperature-switchable compartment. For example, a conventional refrigerator, such as that disclosed in Patent Document 1, has a temperature-switchable compartment in addition to a refrigerator compartment and a freezer compartment. If the refrigerator controls the cooling operation based on the set temperatures of the refrigerator compartment and the freezer compartment, the following problem occurs. After a defrosting operation, the conventional refrigerator cools the freezer compartment for a certain period of time and then starts cooling the freezer compartment and the refrigerator compartment. Here, assume that the user sets the set temperature of the temperature-switchable compartment to, for example, -7°C, which is the freezing temperature range. In this case, when the conventional refrigerator cools the freezer compartment and then switches to cooling the temperature-switchable compartment, the cooler must cool the separate temperature-switchable compartment to the freezing temperature range, which creates a thermal load for cooling the storage compartment to the freezing temperature range again. The heat load on the cooler varies depending on the temperature difference between the set temperature of the temperature switchable compartment and the cooler, and depending on the set temperature of the temperature switchable compartment, the heat exchange efficiency (energy efficiency) between the cooler and the returning cold air may decrease.

[0225] In contrast, in the first embodiment, after a defrosting operation, cooling begins with the first storage compartment, which has the lowest set temperature. However, if the second storage compartment, which has the next lowest set temperature after the first storage compartment, is a temperature-switchable compartment, cooling of the second storage compartment begins only after the temperature of the first storage compartment has a negative gradient over time and the temperature of the first storage compartment has dropped below the set temperature of the second storage compartment. Therefore, in response to the heat load generated by the rise in the internal temperature during the defrosting operation, the storage compartments can be cooled in stages, from those with low heat loads to those with high heat loads, while suppressing the heat load on the cooler 21. This reduces the amount of power consumed by the compressor 24. As a result, energy-saving performance can be improved.

[0226] As described above, the embodiments of the refrigerator of the present disclosure have been described. However, appropriate combinations, modifications, or omissions of the contents described in the first embodiment are also within the scope of the technical idea shown in the first embodiment. Furthermore, although the objects to be cooled stored in the storage compartment have been described as food in the above description, this is not limited thereto. For example, the objects to be cooled may be objects collected from the wild, such as raw meat from small animals that are not edible, or raw meat from animals used in experiments, such as cloned animals.

[0227] Furthermore, the number, types, and arrangement of storage compartments in refrigerator 1 are not limited to those described in the first embodiment. For example, refrigerator 1 may further include another refrigeration compartment such as a vegetable compartment in addition to refrigeration compartment 3, or may include other types of storage compartments. In the first embodiment, the refrigerator 1 has been described as including refrigeration compartment 3 and temperature switchable compartment 4 as storage compartments whose set temperatures are set to 0°C or higher, but refrigerator 1 may also further include a vegetable compartment whose set temperature is set to 3°C to 8°C.

[0228] In the first embodiment, the refrigerator 1 is described as having a configuration in which the switchable compartment return air duct 50 has the first branch air duct 50A, the second branch air duct 50B, and the third branch air duct 50C as the return air duct for the temperature switchable compartment 4, but the configuration is not limited to this. The refrigerator 1 may also be configured to have only one switchable compartment return air duct (not shown) that does not have any branches as the return air duct for the temperature switchable compartment 4.

[0229] REFRIGERATOR LIST 1 Refrigerator, 2 Main body, 3 Refrigerator compartment, 4 Temperature switchable compartment, 5 Freezer compartment, 6 Operation panel, 6a Operation unit, 6b Display unit, 10 Control device, 13 Refrigerator compartment door, 14 Temperature switchable compartment door, 15 Freezer compartment door, 17, 18 Partition wall, 21 Cooler, 22 Fan, 23 Cooler compartment, 24 Compressor, 25 Condenser, 26 Pressure reducing device, 27 Refrigeration cycle circuit, 28 Machine compartment, 29 Cool air duct, 29a First air duct, 29b Second air duct, 29c Third air duct, 31 Refrigerator compartment damper, 32 Temperature switchable compartment damper, 33 Freezer compartment damper, 34 Refrigerator compartment temperature sensor, 35 Temperature switchable compartment temperature sensor, 36 Freezer compartment temperature sensor, 40 Refrigerator compartment return air duct, 41 Refrigerator compartment return port, 42 Refrigerator compartment return air duct inlet, 45 Defrost heater, 46 Outside air temperature sensor, 47 Cooler compartment temperature sensor, 50 Switchable compartment return air duct, 50A First branch air duct, 50B Second branch air duct, 50C Third branch air duct, 51 Switchable compartment return port, 51A First switchable compartment return port, 51B Second switchable compartment return port, 51C Third switchable compartment return port, 52 Switchable compartment return air duct inlet, 60 Freezer compartment return air duct, 61 Freezer compartment return port, 62 Freezer compartment return air duct inlet, 71 Heat transfer tube, 72 Connecting tube, 73 Cooler inlet side, 74 Cooler outlet side, 75 Cooler compartment lowermost region, 76 Cooler lower region, 77 Middle lower cooler region, 78 Middle upper cooler region, 79 Cooler upper region, 81A First branch air duct damper, 81B Second branch air duct damper, 81C Third branch air duct damper, 90 control device, 91 temperature setting unit, 92 temperature acquisition unit, 93 equipment control unit, 94 storage unit, 95 processor, 96 memory, 214 fins, 223 front wall, 224 rear wall.

Claims

1. a first storage compartment set to a first temperature; a second storage chamber set to a second temperature higher than the first temperature; a first temperature sensor for measuring the temperature of the first storage compartment; a second temperature sensor for measuring the temperature of the second storage compartment; a cooler that cools the air by exchanging heat between a refrigerant flowing therein and the air; a cooler chamber that houses the cooler; a compressor that constitutes a part of a refrigeration cycle circuit including the cooler and circulates the refrigerant through the refrigeration cycle circuit; a blower that sends the air cooled in the cooler to the first storage chamber and the second storage chamber; a defrosting heater that melts frost adhering to the cooler; a first air-path opening and closing device provided in a first air path connecting the cooler chamber and the first storage chamber, and configured to open and close the first air path; a second air passage opening and closing device provided in a second air passage connecting the cooler chamber and the second storage chamber, and configured to open and close the second air passage; a control device that receives a temperature of the first storage compartment from the first temperature sensor and a temperature of the second storage compartment from the second temperature sensor, and controls the compressor, the blower, the first air-path opening and closing device, the second air-path opening and closing device, and the defrost heater, The control device a first control that, after performing a defrosting operation in which the defrost heater is energized to melt the frost, opens the first air-path opening and closing device, closes the second air-path opening and closing device, starts the compressor and the blower, and cools the first storage compartment until the gradient of the time change in temperature of the first storage compartment becomes negative and the temperature of the first storage compartment becomes lower than the second temperature; and when the gradient of the change in temperature over time in the first storage compartment becomes negative and the temperature in the first storage compartment becomes lower than the second temperature, executes second control to maintain the open state of the first air-path opening and closing device and switch the second air-path opening and closing device from the closed state to the open state. refrigerator.

2. The control device In the first control, after starting the compressor and the blower, one or both of the rotation speed of the compressor and the rotation speed of the blower are increased in a stepwise manner. The refrigerator according to claim 1.

3. The control device a table indicating the rotation speeds of the compressor and the blower corresponding to the relationship between the outside air temperature and the duration of the defrosting operation is stored; In the first control, the rotation speeds to be set for each of the compressor and the blower at startup are determined based on the table.

3. The refrigerator according to claim 1 or 2.

4. The control device In the first control, a total heat load amount is calculated by adding an outside heat load amount, which is a heat load generated outside the refrigerator, and an inside heat load amount, which is a heat load generated inside the refrigerator, from an outside air temperature and a time of the defrosting operation; setting the rotation speed of the compressor in accordance with the total heat load; 3. The refrigerator according to claim 1 or 2.

5. the second storage chamber is a temperature switchable chamber, The second temperature is set to a chilled temperature range of 0°C or higher and lower than 3°C, a supercooled temperature range of -3°C or higher and lower than 0°C, or a soft freezing temperature range of -10°C or higher and -5°C or lower.

3. The refrigerator according to claim 1 or 2.

6. a third storage chamber set to a third temperature higher than the second temperature; a third temperature sensor for measuring the temperature of the third storage compartment; a third air duct opening and closing device that is provided in a third air duct connecting the cooler chamber and the third storage chamber and that opens and closes the third air duct, the temperature of the third storage compartment is input to the control device from the third temperature sensor; The control device the third air duct opening and closing device is closed during the first control and the second control; When the gradient of the change in temperature over time of the second storage compartment becomes negative in the second control and the temperature of the second storage compartment becomes lower than the third temperature, a third control is executed in which the first air-path opening and closing device and the second air-path opening and closing device are maintained in an open state and the third air-path opening and closing device is switched to an open state to cool the first storage compartment, the second storage compartment, and the third storage compartment.

3. The refrigerator according to claim 1 or 2.

7. The control device In the third control, when the gradient of the temperature change over time in the third storage compartment becomes negative, the gradient of the temperature change over time in the first storage compartment and the gradient of the temperature change over time in the second storage compartment are referenced, and if the gradients of the temperature change over time in each of the first storage compartment and the second storage compartment are negative, control is performed to vary at least one of the rotation speed of the compressor and the rotation speed of the blower. The refrigerator according to claim 6.

8. the third storage compartment is a refrigerator compartment; The third temperature is set to a refrigeration temperature range of 0°C or higher. The refrigerator according to claim 6.

9. a third storage chamber set to a third temperature higher than the second temperature; The cooler chamber includes: a first switching chamber return port through which air returning from the temperature switching chamber to the cooler chamber passes; a second switching chamber return port provided downstream of the first switching chamber return port in the air flow direction, through which air returning from the temperature switching chamber to the cooler chamber is guided; a first return port provided upstream of the first switching chamber return port in the air flow direction, through which air returning from the third storage chamber to the cooler chamber passes; a second return port that opens downstream of the first switching chamber return port and the second switching chamber return port in the air flow direction and through which air returning from the first storage chamber to the cooler chamber is guided; The refrigerator according to claim 5.

10. an air path switching device that switches between a first state in which the return air of the temperature switchable compartment is passed through the first switchable compartment return port and a second state in which the return air of the temperature switchable compartment is passed through the second switchable compartment return port, The control device In normal cooling control for cooling an object to be cooled stored in the first storage chamber or the temperature switchable chamber, When the temperature of the temperature switchable compartment is in a first temperature zone, the air path switching device is switched to the first state; When the temperature of the temperature switchable compartment belongs to a second temperature zone that is lower than the first temperature zone, the air-channel switching device is switched to the second state. The refrigerator according to claim 9.

11. The control device In normal cooling control for cooling the object to be cooled stored in the first storage compartment or the temperature switchable compartment, when the operation of the compressor is stopped and the temperature of the temperature switchable compartment exceeds the upper limit of the second temperature allowable range, the blower is operated to supply the cold air remaining in the cooler compartment to the temperature switchable compartment. The refrigerator according to claim 5.