Storage box

Abstract

Provided is a storage box for cooling a stored object in one temperature zone, the storage box comprising: a body having a storage chamber and a cooler chamber; a door that is provided to a front surface of the storage chamber; a cooler that is disposed in the cooler chamber and that generates cold air by heat exchange with a refrigerant; a blower that sends the cold air to the storage chamber; a compressor that sends the refrigerant to the cooler; an in-chamber temperature sensor that measures an in-chamber temperature which is the temperature of the storage chamber; a cooler chamber temperature sensor that measures a cooler chamber temperature which is the temperature of the cooler chamber; an opening / closing sensor that detects opening / closing of the door; and a control device that controls the compressor and the blower. The control device determines a use frequency rank for each time zone on the basis of the number of times that the door is opened / closed, and if the current time zone is a non-use time zone in which the use frequency rank is the lowest, the control device determines whether a temperature difference between the in-chamber temperature and the cooler chamber temperature is equal to or greater than a threshold temperature. If the temperature difference is equal to or greater than the threshold temperature, the control device executes a suppression operation in which the blower is operated and the compressor is stopped.

Description

storage facility

[0001] The present disclosure relates to a storage facility for cooling and storing stored items such as food.

[0002] Conventionally, refrigerators with improved energy-saving performance have been proposed. For example, Patent Document 1 proposes improving energy-saving performance by devising an air path configuration from the cooler compartment to the freezer compartment of a refrigerator. Specifically, Patent Document 1 proposes that the upper air outlet of the freezer compartment has the largest opening area among the air outlets of the freezer compartment, and that the outlet opening of a cold air duct is located above the blower, and that the upper air outlet of the freezer compartment is located above the outlet opening of the cold air duct. This allows for smooth flow of cold air from the cooler compartment to the freezer compartment, reduces fan power required to send the required air volume, and improves energy-saving performance.

[0003] JP 2011-89735 A

[0004] In recent years, due to changes in lifestyles caused by factors such as an increase in dual-income households and single-person households, as well as the spread of COVID-19, there has been a growing trend toward buying large amounts of food at once and storing them in freezers. Additionally, people are increasingly cooking large quantities of food at once, freezing them for regular use, and using services that provide frozen food for a fixed monthly fee. As a result, freezers are becoming larger in capacity, and an increasing number of users are purchasing freezers as a second storage unit in addition to their refrigerators.

[0005] As the frequency of use of freezers increases, the number of times the door is opened and closed increases, resulting in increased power consumption by freezers. Therefore, there has been a demand for improved energy-saving performance in freezers. Here, even when a freezer employs the air duct configuration described in Patent Document 1, the energy-saving performance can be improved. However, compared with the refrigerator described in Patent Document 1, which performs cooling in multiple temperature zones, a freezer, which performs cooling in a single temperature zone, has room for further improvement in energy-saving performance in terms of operational control of the cooling mechanism.

[0006] The present disclosure is intended to solve the above-mentioned problems and aims to improve the energy-saving performance of a storage facility that cools stored items in a single temperature range.

[0007] The storage facility disclosed herein is a storage facility that cools stored items within a single temperature range, and includes a main body having a storage chamber and a cooler chamber, a door provided on the front of the storage chamber, a cooler located in the cooler chamber and generating cool air by heat exchange with a refrigerant, a blower that sends the cool air to the storage chamber, a compressor that sends the refrigerant to the cooler, an internal temperature sensor that measures the internal temperature of the storage chamber, which is the temperature of the storage chamber, a cooler chamber temperature sensor that measures the cooler chamber temperature, which is the temperature of the cooler chamber, an opening / closing sensor that detects the opening and closing of the door, and a control device that controls the compressor and blower.The control device determines a usage frequency rank for each time period based on the number of times the door is opened and closed, and if the current time period is a non-use time period with the lowest usage frequency rank, determines whether the temperature difference between the internal temperature of the storage chamber and the cooler chamber temperature is greater than or equal to a threshold temperature, and if the temperature difference is greater than or equal to the threshold temperature, performs a suppression operation in which the blower is operated and the compressor is stopped.

[0008] According to the storage facility disclosed herein, during non-use periods, when the temperature difference between the temperature inside the storage facility and the temperature in the cooler compartment is equal to or greater than a threshold temperature, a suppression operation is performed in which the blower is operated and the compressor is stopped, thereby improving energy-saving performance.

[0009] 1 is a front view of a freezer according to embodiment 1. FIG. 2 is a cross-sectional schematic diagram of a freezer according to embodiment 1. FIG. 3 is a schematic diagram of a cooling mechanism of a freezer according to embodiment 1. FIG. 4 is a schematic diagram showing the structure of the interior of a cooler chamber of a freezer according to embodiment 1. FIG. 5 is a control block diagram of a freezer according to embodiment 1. FIG. 6 is a diagram explaining an example of the hardware configuration of a control device of a freezer according to embodiment 1. FIG. 7 is a diagram explaining another example of the hardware configuration of a control device of a freezer according to embodiment 1. FIG. 8 is a flowchart showing the operation of a freezer according to embodiment 1. FIG. 9 is a diagram explaining changes in an internal temperature Tf when a freezer compartment door is opened and closed in embodiment 1. FIG. 10 is a flowchart showing a method for calculating an adjustment coefficient α in embodiment 1. FIG. 11 is a flowchart showing a method for measuring a temperature rise value and a recovery time when the door is opened and closed in embodiment 1. FIG. 12 is a flowchart showing a method for measuring a recovery time when the door is opened and closed in embodiment 1. FIG. 13 is a diagram explaining suppression operation of a freezer according to embodiment 1. FIG. 14 is a flowchart showing the flow of normal operation in a freezer according to embodiment 1. FIG. 15 is a flowchart showing the flow of suppression operation in a freezer according to embodiment 1. FIG. 16 is a ph diagram showing the effect obtained by performing suppression operation in a freezer according to embodiment 1. FIG. 17 is a flowchart showing the operation of a freezer according to embodiment 2. 1 is an example of a graph showing changes in the number of times the freezer compartment door is opened and closed, the usage frequency rank, and the set temperature Tfs of the freezer compartment in a freezer according to embodiment 2. A flowchart showing the operation of a freezer according to embodiment 3. An example of a table showing set ranks according to the usage frequency rank and the outdoor air rank of a freezer according to embodiment 3. An example of a graph showing the number of times the freezer compartment door is opened and closed, the usage frequency rank, and the set rank in a freezer according to embodiment 3. A flowchart showing the operation of a freezer according to embodiment 4. A flowchart showing the flow of special defrosting operation of a freezer according to embodiment 4. A diagram for explaining the electric input and the cooler compartment temperature in the defrosting operation at low outdoor air temperatures in a conventional freezer. A diagram for explaining the electric input and the cooler compartment temperature in the defrosting operation at low outdoor air temperatures in a freezer according to embodiment 4. A diagram for comparing the length of heater energization time between a conventional freezer and a freezer according to embodiment 4. A front view of a freezer according to modification 1.FIG. 10 is a cross-sectional schematic view of a freezer according to a first modified example.

[0010] Hereinafter, an embodiment of a storage facility according to the present disclosure will be described with reference to the drawings. In each drawing, the same reference numerals denote the same or equivalent parts, and this is common throughout the specification. Other steps may be included between the steps of the flowchart of the present disclosure. In each drawing, the relative dimensions or shapes of the components may differ from those in reality.

[0011] Embodiment 1. <Configuration of Freezer 1> In Embodiment 1, as an example of a storage facility, a freezer 1 that cools and stores items to be stored in a freezing temperature range will be described. FIG. 1 is a front view of freezer 1 according to Embodiment 1. FIG. 2 is a schematic cross-sectional view of freezer 1 according to Embodiment 1. FIG. 2 is a view of freezer 1 shown in FIG. 1 cut along line A-A and viewed from the direction of the arrow. In the following description, to facilitate understanding, terms indicating directions, such as "up," "down," "right," "left," "front," "nearby," "rear," and "back," will be used as appropriate. However, these terms are for the purpose of explanation and do not limit the embodiments. In addition, in the embodiment, the terms "up," "down," "right," "left," "front," "nearby," "rear," and "back" will be used when viewing freezer 1 in use from the front.

[0012] As shown in Figures 1 and 2, the freezer 1 includes a main body 2 having an opening at the front and a storage compartment formed therein. The main body 2 includes a steel outer box 21, a resin inner box 22, and a heat insulating member 23 filled in the space between the outer box 21 and the inner box 22. The outer box 21 is made of a metal such as steel and has an opening at the front. The inner box 22 is made of resin and is fitted into the outer box 21 through the opening. The heat insulating member 23 is made of, for example, urethane foam or vacuum insulation material, and is filled in the space between the outer box 21 and the inner box 22.

[0013] The storage compartment provided within the main body 2 is a freezer compartment 10. The freezer compartment 10 is composed of an upper freezer compartment 11 and a lower freezer compartment 12. However, no partition is provided between the upper freezer compartment 11 and the lower freezer compartment 12, and the upper freezer compartment 11 and the lower freezer compartment 12 are a single space set to the same temperature range. By not providing a partition within the freezer compartment 10, it is possible to increase the internal volume of the freezer 1 compared to conventional freezers that separate the upper and lower freezer compartments with a partition. In this embodiment, the space to which cold air is supplied from air outlets 51a to 51c located above the blower 35 (described later) is referred to as the upper freezer compartment 11, and the space to which cold air is supplied from air outlets 52a to 52c located below the blower 35 is referred to as the lower freezer compartment 12. In other words, the space supplied with cold air blown from the blower 35 in the direction opposite to the direction of gravity is referred to as the upper freezer compartment 11, and the space supplied with cold air blown from the blower 35 in the direction of gravity is referred to as the lower freezer compartment 12.

[0014] The freezer compartment 10 is provided with multiple shelves 13 on which food and other stored items are placed, and multiple storage containers 14 for storing the stored items. More specifically, the upper freezer compartment 11 is provided with two shelves 13 and one storage container 14, while the lower freezer compartment 12 is provided with three storage containers 14. The shelves 13 are, for example, glass shelves. The storage containers 14 are, for example, sliding cases that can be pulled out forward. The storage containers 14 are supported by case frames (not shown) provided on the left and right inner walls of the upper freezer compartment 11 and the lower freezer compartment 12, and are configured to slide back and forth independently of the opening and closing of the freezer compartment door 15.

[0015] By providing the top two shelves 13 in the upper freezer compartment 11, items that will be used within a short period of time or frequently used items can be easily taken out, improving convenience. In addition, by storing items that will be stored for a long period of time in the storage container 14 in the lower freezer compartment 12, the effects of temperature changes caused by opening and closing the freezer compartment door 15 can be suppressed.

[0016] The upper freezer compartment 11 and the lower freezer compartment 12 are set in a freezing temperature range. The freezing temperature range is a temperature range below 0°C, which is sufficiently lower than the refrigeration temperature range. The freezing temperature range is, for example, a temperature range of -20°C or higher and -18°C or lower.

[0017] An opening formed in the front of the freezer compartment 10 is provided with a single-wing freezer compartment door 15 for opening and closing the opening. The freezer compartment door 15 is divided into an upper door 15a provided in front of the upper freezer compartment 11 and a lower door 15b provided in front of the lower freezer compartment 12. The upper door 15a and the lower door 15b are attached to the main body 2 via hinges provided in the main body 2 and are opened and closed separately. The configuration of the freezer compartment door 15 is not limited to the example shown in Figures 1 and 2. For example, the upper door 15a and the lower door 15b may each be a double-wing door or a drawer door.

[0018] A door partition 16 is provided between the upper door 15a and the lower door 15b to separate the upper door 15a and the lower door 15b. As shown in Fig. 2, the door partition 16 is provided only on the front side of the freezer compartment 10, and does not separate the upper freezer compartment 11 and the lower freezer compartment 12. The door partition 16 is provided with an opening / closing sensor 17 that detects the opening and closing of the upper door 15a and the lower door 15b.

[0019] The open / close sensor 17 includes an actuating unit provided on the rear side of the upper door 15a and the lower door 15b and a detecting unit provided in the door partition 16. The detecting unit is, for example, a magnetic sensor such as a reed switch or a low-current Hall IC operating at 48 V or less. The actuating unit activates the detecting unit when brought close to the detecting unit, and is, for example, a magnet. The open / close sensor 17 may also be configured as a single unit such as a push button switch. Configuring the detecting unit of the open / close sensor 17 as a parallel circuit makes it possible to determine whether the upper door 15a or the lower door 15b is open, or whether both doors are open. In this embodiment, the open / close sensor 17 transmits an open signal to the control device 6 indicating that the freezer compartment door 15 is open when at least one of the upper door 15a and the lower door 15b is opened. That is, in this embodiment, a state in which at least one of the upper door 15a and the lower door 15b is open is referred to as an open state, and a state in which both the upper door 15a and the lower door 15b are closed is referred to as a closed state.

[0020] An operation display unit 18 is provided on the outer surface of the upper door 15a. The operation display unit 18 includes an operation unit 18a that accepts operations from the user, and a display unit 18b that displays temperature information of the freezer compartment 10, inventory information, and notifications for the user. The operation unit 18a has a plurality of operation buttons, and the user can set the temperature of the freezer compartment 10, etc., by operating the operation unit 18a. The display unit 18b is, for example, a liquid crystal display. The operation display unit 18 may be configured as a touch panel in which the operation unit 18a is integrally formed on the display unit 18b.

[0021] An outside air temperature sensor 19 is provided inside the operation display unit 18 to measure an outside air temperature Ta, which is the temperature of the space outside the freezer compartment separated from the freezer compartment 10 by the freezer compartment door 15. The outside air temperature sensor 19 is, for example, a thermistor. The outside air temperature Ta measured by the outside air temperature sensor 19 is output to the control device 6.

[0022] A control device 6 that controls each part of the freezer 1 is provided on the rear side of the upper part of the freezer 1. Based on input from the operation unit 18a and output from each sensor, the control device 6 controls the cooling mechanism and each heater, which will be described later, to perform a cooling operation for cooling the freezer compartment 10 and a defrosting operation for defrosting the cooler 34. The configuration and control of the control device 6 will be described in detail later.

[0023] A cooling mechanism that supplies cold air is provided on the rear side of the freezer compartment 10. Fig. 3 is a schematic diagram of the cooling mechanism of the freezer 1 according to the first embodiment. As shown in Fig. 3, the freezer 1 includes a compressor 31, a condenser 32, a pressure reducing device 33, a cooler 34, and a blower 35 as the cooling mechanism that supplies cold air. The compressor 31, the condenser 32, the pressure reducing device 33, and the cooler 34 are connected by refrigerant pipes to form a refrigerant circuit. The solid arrows in Fig. 3 indicate the direction in which the refrigerant circulates in the refrigerant circuit.

[0024] The compressor 31 compresses the refrigerant to a high-temperature, high-pressure gaseous state. As shown in Fig. 2, the compressor 31 is disposed in a machine room 30 provided below the cooler room 3 on the rear side of the main body 2 of the freezer 1. The high-temperature, high-pressure refrigerant flowing out of the compressor 31 flows into the condenser 32. The condenser 32 dissipates heat from the refrigerant flowing in from the compressor 31, causing the refrigerant to condense. The condenser 32 is, for example, a fin-and-tube heat exchanger.

[0025] The refrigerant condensed in the condenser 32 flows into the pressure reducing device 33. The pressure reducing device 33 reduces the pressure of the refrigerant flowing in from the condenser 32 to a two-phase state of liquid and gas. The pressure reducing device 33 is, for example, a capillary tube. The two-phase refrigerant of liquid and gas that flows out of the pressure reducing device 33 flows into the cooler 34. In other words, the compressor 31 sends the refrigerant to the cooler 34 via the condenser 32 and the pressure reducing device 33.

[0026] The cooler 34 evaporates the two-phase refrigerant decompressed by the pressure reducing device 33, and cools the air around the cooler 34 by the heat absorption effect caused by the evaporation of the refrigerant. That is, the cooler 34 functions as an evaporator in the refrigerant circuit. The cooler 34 is, for example, a fin-and-tube heat exchanger. The refrigerant flowing out of the cooler 34 returns to the compressor 31. By repeating this cycle, the cooler 34 generates cold air.

[0027] The cool air generated by the cooler 34 is sent to the freezing compartment 10 by the blower 35. The blower 35 is, for example, an axial flow fan. The rotation speed of the blower 35 is controlled by the control device 6.

[0028] FIG. 4 is a schematic diagram showing the structure inside the cooler compartment 3 of the freezer 1 according to the first embodiment. The dashed arrow in FIG. 4 indicates the air flow direction D1 in the cooler compartment 3. The cooler 34 disposed in the cooler compartment 3 generates cold air by heat exchange with the refrigerant. The cooler 34 includes a plurality of heat transfer tubes 342 each having a smooth surface and a plurality of thin plate-like fins 341, and a plurality of U-shaped connecting tubes 343. The heat transfer tubes 342 are arranged vertically. For example, six heat transfer tubes 342 are arranged vertically. Two adjacent heat transfer tubes 342 are connected at one end in the left-right direction by the connecting tube 343. This forms a continuous refrigerant tube.

[0029] The refrigerant flowing through the refrigerant pipes of the cooler 34 flows from an inlet 34a connected to the lowest heat transfer pipe 342 to an outlet 34b connected to the highest heat transfer pipe 342. Air in the cooler chamber 3 flows in a direction D1 from below to above the cooler 34 by an air blower 35 provided at the top of the cooler chamber 3. Therefore, the lowest heat transfer pipe 342 is disposed on the most upstream side of the multiple heat transfer pipes 342 with respect to the air flow direction D1. Furthermore, the uppermost heat transfer pipe 342 is disposed on the most downstream side of the multiple heat transfer pipes 342 with respect to the air flow direction D1.

[0030] The low-temperature refrigerant in a gas-liquid two-phase state flowing in from the pressure reducing device 33 flows from the inlet 34a of the cooler 34 through the heat transfer tube 342 located furthest upstream relative to the air flow direction D1, and then flows through the heat transfer tubes 342 located gradually downstream to reach the outlet 34b of the cooler 34. As the two-phase refrigerant flowing through the cooler 34 moves from the inlet 34a to the outlet 34b of the cooler 34, it exchanges heat with the air flowing outside the heat transfer tube 342. As a result, the two-phase refrigerant flows through the heat transfer tube 342 while the liquid phase in the refrigerant evaporates. Normally, the temperature of the refrigerant at the inlet 34a of the cooler 34 is lower than the temperature of the refrigerant at the outlet 34b.

[0031] A return air duct 54 for cool air from the freezing compartment 10 is provided in the lower region of the cooler compartment 3. As a result, the return air from the freezing compartment 10 passes from the inlet 34a to the outlet 34b of the cooler 34, i.e., from the upstream end to the downstream end of the cooler 34 in the air flow direction D1. This maximizes the heat exchange distance between the return air from the freezing compartment 10 and the cooler 34. As a result, the return air from the freezing compartment 10 hits the entire volume of the cooler 34, making it possible to cool using the entire cooler 34, and improving the heat exchange capacity with the refrigerant in the cooler 34.

[0032] The cooler chamber 3 is also provided with a cooler chamber temperature sensor 36 that measures the cooler chamber temperature Te, which is the temperature of the air in the cooler chamber 3. The cooler chamber temperature sensor 36 is, for example, a thermistor. The cooler chamber temperature Te measured by the cooler chamber temperature sensor 36 is output to the control device 6.

[0033] 2 , the freezer 1 includes a defrost heater 41 provided in the cooler compartment 3, a drain pipe 42 and a drain heater 43 provided between the cooler compartment 3 and the machine compartment 30, and a drain pan 44 provided in the machine compartment 30. The defrost heater 41 is a heater that generates heat when energized, and melts frost adhering to the cooler 34.

[0034] The drain pipe 42 discharges meltwater produced by melting frost adhering to the cooler 34 into the drain pan 44. The drain heater 43 generates heat when energized and unfreezes the drain pipe 42. The drain heater 43 also melts the remaining ice that has fallen from the cooler 34 and guides it to the drain pipe 42 and then to the drain pan 44. The provision of the drain heater 43 prevents some of the meltwater from remaining in the cooler chamber 3 in the form of ice, which then solidifies and closes the drain pipe 42.

[0035] The melted frost water guided to the drain pan 44 is stored in the drain pan 44 and evaporates over a certain period of time in the machine room 30, which is heated to a high temperature by the heat generated by the compressor 31. The volume of the drain pan 44 is larger than the volume of the cooler 34, and is, for example, approximately 1.5 to 2.0 L. By making the volume of the drain pan 44 larger than the volume of the cooler 34, it is possible to prevent the water in the drain pan 44 from overflowing and spilling into the machine room 30.

[0036] The defrost heater 41 and the drain heater 43 are operated synchronously by the control device 6 during defrosting operation. Although the drain heater 43 is arranged adjacent to the drain pipe 42 in Fig. 2, the shape and arrangement of the drain heater 43 are not limited to the example in Fig. 2. For example, the drain heater 43 may be made of an aluminum foil heater or the like and wrapped around the drain pipe 42.

[0037] Inside the main body 2 of the freezer 1, there are provided an upper air duct 51 for supplying the cold air generated by the cooler 34 to the upper freezer compartment 11, and a lower air duct 52 for supplying the cold air to the lower freezer compartment 12. The cold air in the cooler compartment 3 is caused by the blower 35 to flow in an air flow direction D1 from below to above the cooler 34. In this embodiment, the blower 35 is controlled so that an appropriate amount of cold air is supplied to each of the upper air duct 51 and the lower air duct 52.

[0038] The upper air duct 51 is provided with air outlets 51a to 51c that connect the upper freezer compartment 11 and the cooler compartment 3. The air outlet 51a blows cool air into a first area A1, which is a storage space on the top shelf 13 of the freezer compartment 10. The air outlet 51b blows cool air into a second area A2, which is a storage space on the second shelf 13 from the top of the freezer compartment 10. The air outlet 51c blows cool air into a third area A3, which is a storage space inside a storage container 14, which is the third storage space from the top of the freezer compartment 10.

[0039] The lower air duct 52 is provided with air outlets 52a to 52c that connect the lower freezer compartment 12 and the cooler compartment 3. The air outlet 52a blows cool air into a fourth area A4, which is a storage space within the storage container 14 located fourth from the top of the freezer compartment 10. The air outlet 52b blows cool air into a fifth area A5, which is a storage space within the storage container 14 located fifth from the top of the freezer compartment 10. The air outlet 52c blows cool air into a sixth area A6, which is a storage space within the storage container 14 located sixth from the top of the freezer compartment 10, in other words, the lowest area of ​​the freezer compartment 10.

[0040] The upper air duct 51 and the lower air duct 52 are not provided with dampers to adjust the amount of cool air blown into the upper freezer compartment 11 and the lower freezer compartment 12. This is because the freezer compartment 10 is controlled to the same set temperature range, and the area of ​​each air outlet is designed in advance to match the insulation specifications of the freezer 1, the specifications of the cooler 34, and the specifications of the compressor 31 so that the temperature inside the freezer compartment 10 is approximately uniform. Therefore, the freezer 1 can be controlled to the target set temperature without using any extra parts. This reduces the number of parts used, allowing the internal volume of the freezer 1 to be expanded.

[0041] An internal temperature sensor 53 for measuring an internal temperature Tf, which is the temperature inside the freezer compartment 10, is provided near the center of the freezer compartment 10, which is the intermediate region between the upper freezer compartment 11 and the lower freezer compartment 12. The internal temperature sensor 53 is, for example, a thermistor. In the example of FIG. 2 , the internal temperature sensor 53 is provided on the wall surface 520 on the back side of the fourth area A4 of the lower freezer compartment 12, but the location of the internal temperature sensor 53 is not limited thereto. Alternatively, multiple internal temperature sensors 53 may be provided inside the freezer compartment 10, and the average of the measured values ​​may be used as the internal temperature Tf of the freezer compartment 10. The internal temperature Tf measured by the internal temperature sensor 53 is output to the control device 6.

[0042] Furthermore, a return air duct 54 is provided on the rear side of the sixth area A6 of the lower freezer compartment 12. The return air duct 54 is an air duct for guiding air that has passed through the upper freezer compartment 11 and the lower freezer compartment 12 to the cooler compartment 3. The air that has passed through the upper freezer compartment 11 and the lower freezer compartment 12 flows into the cooler compartment 3 through an inlet 54a of the return air duct 54. The inlet 54a of the return air duct 54 is provided away from the respective outlets of the upper air duct 51 and the lower air duct 52. In Fig. 2, the inlet 54a is provided at the bottom of the freezer compartment 10, but the position of the inlet 54a is not limited to that shown in Fig. 2 as long as it is provided on a wall surface within the freezer compartment 10.

[0043] Next, the configuration of the air passage in the freezer 1 according to this embodiment will be described. In the freezer 1, the freezer compartment 10 is cooled mainly by indirect cooling using cooled air. In this embodiment, the air passage is configured so that the amounts of cold air Q1 to Q6 blown into the first area A1 to the sixth area A6 in the freezer compartment 10 (the amount of capacity to cool an object in each area) satisfy the relationship Q1 > Q2 > Q3 > Q4 > Q5 > Q6. In other words, the air passage is configured so that the amount of cold air in the upper area is greater than the amount of cold air in the lower area.

[0044] The amount of cold air Q can be roughly calculated using the following formula (1): where M is mass [kg], C is specific heat [J / (kg·K)], and ΔT is the temperature difference [K] between the cold air and the object to be cooled. Q≒M×C×ΔT (1)

[0045] In the case of cooling air in the freezer 1, the amount of cold air Q can be roughly calculated by the following formula (2): ａｉｒ is the air density [kg / m ３ ], Fn is the flow rate in each area [m ３ / s]. Q ≒ ρ ａｉｒ ×Fn×C×ΔT ... (2)

[0046] In other words, the air passage configuration of freezer 1 is determined so that the relationship (F1×T1×ss1)>>(F2×T2×ss2)>>(F3×T3×ss3)>>(F4×T4×ss4)>>(F5×T5×ss5)>>(F6×T6×ss6) holds, where F1 to F6 are the airflow rates from each air outlet, T1 to T6 are the airflow temperatures, and ss1 to ss6 are the airflow areas. As a result, the amount of cold air per unit time flowing in from air outlets 51a to 51c and 52a to 52c increases toward the top of freezer compartment 10 and decreases toward the bottom.

[0047] When the above relationship of the amount of cold air is established, the amount of cold air increases as the discharge flow rate of each outlet increases, the discharge temperature decreases, and the discharge area increases. Therefore, the discharge flow rate, discharge temperature, and discharge area are basically configured to decrease from the top to the bottom of the freezer compartment 10.

[0048] As described above, by adjusting the amount of cold air from the air outlets 51a to 51c and 52a to 52c in the freezer 1, it is possible to more efficiently cool the inside of the freezer compartment 10. The colder the cold air, the more it sinks in the direction of gravity, so the cold air circulates from top to bottom within the freezer compartment 10. Therefore, by increasing the amount of cold air in the upper part of the freezer compartment 10, the cold air can be circulated in order from the top, thereby increasing cooling efficiency and improving energy-saving performance.

[0049] In addition, in freezer 1, the cross-sectional area of ​​upper air passage 51 is larger than the cross-sectional area of ​​lower air passage 52. The wall surface on the rear side of lower air passage 52 is inclined, and the cross-sectional area of ​​lower air passage 52 becomes smaller toward the bottom. This makes the pressure loss in upper air passage 51 smaller than the pressure loss in lower air passage 52, and allows the amount of cold air flowing through upper air passage 51 to be larger than the amount of cold air flowing through lower air passage 52.

[0050] Furthermore, the insulation thickness of wall surface 510 separating upper air duct 51 from upper freezer compartment 11 is greater than the insulation thickness of wall surface 520 separating lower air duct 52 from lower freezer compartment 12. This makes the insulation capacity of upper freezer compartment 11 greater than that of lower freezer compartment 12. Furthermore, the specifications of the insulation material of wall surface 510 and wall surface 520 may be adjusted so that the insulation capacity of upper freezer compartment 11 is greater than that of lower freezer compartment 12.

[0051] The higher up in the freezer compartment 10, the greater the distance from the cooler 34, and the temperature difference between the cold air and the storage space tends to be gradually lost while the cold air is being sent. In response to this, by making the insulation thickness of the wall surface 510 of the upper air duct 51 greater than the insulation thickness of the wall surface 520 of the lower air duct 52 as described above, it is possible to suppress a decrease in the cooling effect in the upper part of the freezer compartment 10. As a result, it is possible to suppress a decrease in the temperature (absolute value) of the cold air supplied to the upper freezer compartment 11, and it is possible to increase the amount of cold air in the upper freezer compartment 11. When controlling the temperature of the freezer 1, the cold air is in the negative temperature range, and the above-described insulation structure allows the cold air in the negative temperature range to be supplied to the upper freezer compartment 11 while remaining as cold as possible.

[0052] Furthermore, heat enters freezer compartment 10 through the outside air from the ceiling surface of main body 2 and through condenser 32 provided within main body 2. Furthermore, upper door 15a, which opens and closes upper freezer compartment 11, tends to be used more frequently by users than lower door 15b, and upper freezer compartment 11 receives more heat from the outside than lower freezer compartment 12. Therefore, by making the insulating capacity of upper freezer compartment 11 greater than that of lower freezer compartment 12, the temperature difference between upper freezer compartment 11 and lower freezer compartment 12 can be reduced, and temperature unevenness within freezer compartment 10 can be suppressed.

[0053] Furthermore, the blower 35 is positioned so as to blow cool air diagonally upward relative to the direction of gravity. The angle of the blower 35 relative to the direction of gravity is, for example, 35 to 40 degrees. The shape of the wall surface 520 in front of the blower 35 is designed to guide the cool air so that the flow rate of the cool air blown out from the blower 35 at the top is greater than the flow rate at the bottom.

[0054] <Operation of Freezer 1> Next, a description will be given of the operation of the freezer 1. Fig. 5 is a control block diagram of the freezer 1 according to embodiment 1. As shown in Fig. 5, the control device 6 of the freezer 1 has a storage unit 61, a cooling control unit 62, a heater control unit 63, an adjustment coefficient calculation unit 64, a rank determination unit 65, and a determination unit 66.

[0055] The storage unit 61 stores programs executed by the control device 6 and information used in the programs. For example, the storage unit 61 stores setting information input via the operation / display unit 18, parameters such as programs and thresholds used in the cooling operation and defrosting operation, and parameters such as programs and thresholds used to calculate adjustment coefficients and determine ranks, which will be described later. The storage unit 61 also stores the number of times the freezer compartment door 15 has been opened and closed in the past, the opening time of the freezer compartment door 15 when it was opened, along with date and time information. The storage unit 61 may be provided separately from the control device 6.

[0056] The cooling control unit 62 cools the freezer compartment 10 based on the measurement results of each sensor in the freezer 1, setting information input via the operation and display unit 18, and the determination result of the determination unit 66. Specifically, the cooling control unit 62 controls the rotation speed of the compressor 31 and the rotation speed of the blower 35 so that the inside temperature Tf measured by the inside temperature sensor 53 becomes a preset set temperature Tfs. Furthermore, the cooling control unit 62 performs either normal operation or suppressed operation based on the determination result of the determination unit 66.

[0057] The heater control unit 63 controls the energization state of the defrost heater 41 and the drain heater 43. Specifically, when performing a defrosting operation, the heater control unit 63 synchronously energizes the defrost heater 41 and the drain heater 43. The defrosting operation is performed when a defrosting condition is satisfied during the cooling operation.

[0058] The adjustment coefficient calculation unit 64 calculates an adjustment coefficient α used by the rank determination unit 65 to determine the usage frequency rank. The adjustment coefficient α is a numerical value between 0 and 1 that indicates the proportion of a load (stored items) introduced into the freezer compartment 10 when the freezer compartment door 15 is opened or closed. The adjustment coefficient calculation unit 64 determines whether or not a load was introduced when the freezer compartment door 15 was opened or closed during a previously set calculation period, based on the temperature rise value ΔTf and recovery time tf of the inside temperature Tf when the freezer compartment door 15 was opened or closed, and the temperature rise value ΔTe and recovery time te of the cooler compartment temperature Te, and calculates the adjustment coefficient α.

[0059] At the beginning of use of the freezer 1, the adjustment coefficient calculation unit 64 may set the calculated result of the adjustment coefficient α to an initial value of 0.5. Then, as will be described later, an adjustment coefficient α suited to the user is calculated as the user continues to use the freezer 1, and this is reflected in the usage frequency rank. The adjustment coefficient calculation unit 64 is not essential, and the adjustment coefficient α may be set to 1 when calculating the usage frequency rank.

[0060] The rank determination unit 65 determines the usage frequency rank of the freezer 1 for each time period. A time period is, for example, an hourly time period starting from midnight. The rank determination unit 65 multiplies the average number of times the freezer compartment door 15 is opened and closed, the average open time, and the adjustment coefficient α calculated by the adjustment coefficient calculation unit 64 for the same time period during a preset calculation period to determine the discrimination parameter X. The preset calculation period is, for example, the most recent week excluding the current day. As an example, the discrimination parameter X for the time period from 7:00 to 8:00 today is the product of the average number of times the freezer compartment door 15 is opened and closed, the average open time, and the adjustment coefficient α for the week prior to yesterday. If the average number of times the freezer compartment door 15 is opened and closed between 7:00 and 8:00 during the week prior to yesterday is 5 times, the average open time is 5 minutes, and the adjustment coefficient α is 0.5, the discrimination parameter X is 12.5.

[0061] The rank determination unit 65 compares the obtained discrimination parameter X with a preset threshold value to determine the usage frequency rank. As an example, the rank determination unit 65 classifies the usage frequency rank for each time period into five levels, FR1 to FR5, as shown below, according to the discrimination parameter X. Note that the threshold values ​​compared with the discrimination parameter X below are those when the adjustment coefficient α is set to 0.5, and when the adjustment coefficient α is set to 1, each threshold value is doubled. Specifically, the threshold value for the usage frequency rank FR1 is "X≦20". 1) Usage frequency rank FR1: X≦10 2) Usage frequency rank FR2: 10<X≦50 3) Usage frequency rank FR3: 50<X≦100 4) Usage frequency rank FR4: 100<X≦150 5) Usage frequency rank FR5: 150<X

[0062] Use frequency rank FR1 is the least frequently used, and use frequency rank FR5 is the most frequently used. Use frequency rank FR1 corresponds to a time period when the device is not in use, use frequency ranks FR2 and FR3 correspond to time periods when the device is used less frequently, and use frequency ranks FR4 and FR5 correspond to time periods when the device is used more frequently. Note that the number of use frequency rank levels is not limited to five, and the levels can be classified into any number of levels equal to or greater than two.

[0063] The number of times that the freezer door 15 is opened and closed during each time period of the day varies from user to user, with some users opening and closing the door approximately 80 times per day. The duration of time that the freezer door 15 is open during each opening and closing also varies from user to user, with some users closing the door within 30 seconds on average, while others leave it open for several minutes on average while searching for ingredients. The threshold value (≦10) for the usage frequency rank FR1 assumes that the number of openings and closings is less than 10 times and the opening time per opening and closing is less than 1 minute, and this time period is considered a non-use time period.

[0064] The determination unit 66 determines whether to perform normal operation or suppressed operation during cooling operation based on the use frequency rank determined by the rank determination unit 65. More specifically, the determination unit 66 determines to perform suppressed operation if the use frequency rank of the current time period is the lowest rank FR1, i.e., if it is a non-use time period, and determines to perform normal operation if the use frequency rank of the current time period is other than FR1. The determination result of the determination unit 66 is sent to the cooling control unit 62.

[0065] Here, the hardware configuration of the control device 6 of the freezer 1 of this embodiment will be described. FIG. 6 is a diagram illustrating an example of the hardware configuration of the control device 6 of the freezer 1 according to the first embodiment. When the cooling control unit 62, the heater control unit 63, the adjustment coefficient calculation unit 64, the rank determination unit 65, and the determination unit 66 of the control device 6 are implemented in hardware, the control device 6 is configured with a processing circuit 600. The processing circuit 600 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. The cooling control unit 62, the heater control unit 63, the adjustment coefficient calculation unit 64, the rank determination unit 65, and the determination unit 66 may each be implemented by separate processing circuits 600, or each unit may be implemented by a single processing circuit 600.

[0066] 7 is a diagram illustrating another example of the hardware configuration of the control device 6 of the freezer 1 according to the first embodiment. When the cooling control unit 62, heater control unit 63, adjustment coefficient calculation unit 64, rank determination unit 65, and judgment unit 66 of the control device 6 are realized by software, the control device 6 has a processor 601 such as a CPU or GPU, and a memory 602. The processor 601 and the memory 602 are communicatively connected to each other via a bus 603. Note that the control device 6 may have a plurality of processors 601 and a plurality of memories 602, which cooperate to realize the cooling control unit 62, heater control unit 63, adjustment coefficient calculation unit 64, rank determination unit 65, and judgment unit 66.

[0067] The cooling control unit 62, heater control unit 63, adjustment coefficient calculation unit 64, rank determination unit 65, and judgment unit 66 are realized by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in memory 602. The processor 601 realizes each unit by reading and executing the programs stored in memory 602. The memory 602 constitutes the storage unit 61 and is, for example, a non-volatile semiconductor memory such as a ROM or a flash memory, a volatile semiconductor memory such as a RAM, or a recording medium such as an HDD or SSD.

[0068] Fig. 8 is a flowchart showing the operation of the freezer 1 according to the first embodiment. The operation of Fig. 8 is started by the control device 6 at midnight every day and finished at midnight. First, the rank determination unit 65 of the control device 6 calculates an adjustment coefficient α (S1). Then, the rank determination unit 65 determines a usage frequency rank for each time slot of the day (S2). As described above, the usage frequency rank is determined based on the discrimination parameter X obtained by multiplying the adjustment coefficient α by the average number of times the freezer compartment door 15 is opened and closed over the most recent week and the average duration for which the door is open.

[0069] The determination unit 66 determines whether the usage frequency rank of the current time period corresponds to a non-use time period (S3). If the usage frequency rank is the lowest rank FR1, the determination unit 66 determines that the time period is a non-use time period. If the usage frequency rank does not correspond to a non-use time period (S3: NO), the determination unit 66 determines that normal operation should be performed, and the cooling control unit 62 performs normal operation (S4).

[0070] If the usage frequency rank corresponds to a non-use time period (S3: YES), that is, if the usage frequency rank is FR1, the determination unit 66 determines that suppression operation should be performed, and the suppression operation is performed by the cooling control unit 62 (S5). Thereafter, the process returns to step S3, and suppression operation or normal operation is performed for each time period.

[0071] Next, a method for calculating the adjustment coefficient α performed in step S1 of Fig. 8 will be described. Fig. 9 is a diagram illustrating the change in the inside temperature Tf when the freezer compartment door 15 is opened and closed in embodiment 1. Fig. 9 shows the change in power [W] over time, the operation (ON) and stoppage (OFF) of the compressor 31 and the blower 35, and the change in the inside temperature Tf measured by the inside temperature sensor 53 over time.

[0072] In the cooling operation for cooling the freezer compartment 10, the cooling control unit 62 of the freezer 1 synchronizes the compressor 31 and the blower 35 and switches between operation and stop so that the inside temperature Tf falls within the allowable range Tfs±dθf, with the set temperature Tfs as the target value. The allowable range dθf varies depending on the insulation specifications of the freezer 1 and the specifications of the cooler 34, but is, for example, 2 to 4 [K].

[0073] This controls the temperature and flow rate of the cold air blown into the freezer compartment 10, and the average value of the inside temperature Tf of the freezer compartment 10 of the freezer 1 is maintained at the set temperature Tfs. In other words, the operation or stop of the compressor 31 and the blower 35 is synchronized with the inside temperature Tf of the freezer compartment 10, and the freezer compartment 10 is cooled while the compressor 31 is operating, and cooling is temporarily stopped while the compressor 31 is stopped, and the inside temperature Tf tends to rise.

[0074] The following describes changes in the freezer temperature Tf when the freezer door 15 is opened and closed during normal operation. In Fig. 9 , the solid line after the freezer door 15 is opened indicates the change in the freezer temperature Tf when no load is applied to the freezer compartment 10 when the freezer door 15 is opened and closed, and the dashed line indicates the change in the freezer temperature Tf when a load is applied to the freezer compartment 10 when the door 15 is opened and closed. When a load is applied to the freezer compartment 10 when the freezer door 15 is opened and closed (the dashed line in Fig. 9 ), the rise in the freezer temperature Tf is greater than when no load is applied to the freezer compartment 10 (the solid line in Fig. 9 ). Furthermore, when a load is applied to the freezer compartment 10, the recovery time tf_load required for the freezer temperature Tf to return to the temperature immediately before the freezer door 15 was opened is longer than the recovery time tf_unload when no load is applied.

[0075] This is because the thermal load on the freezer 1 is greater when a new load is introduced into the freezer compartment 10. When the door is opened and closed only, the inside temperature Tf rises due to the cold air leaking from the freezer compartment 10 to the outside, but when a new load is introduced into the freezer compartment 10, in addition to the temperature rise due to the cold air leak, it becomes necessary to additionally cool the load with a certain amount of heat. In other words, the additional thermal load of the load is applied to the freezer 1 (cooler 34), and it takes time to cool it down.

[0076] In this way, the temperature rise in the interior temperature Tf differs depending on whether or not a load is applied to the freezer compartment 10 when the freezer compartment door 15 of the freezer 1 is opened or closed, and the cooling capacity required for the freezer 1 also differs. The cooler compartment temperature Te also changes in the same way as the interior temperature Tf. That is, if a load is applied to the freezer compartment 10 when the freezer compartment door 15 is opened or closed, the temperature rise in the cooler compartment temperature Te is greater than when no load is applied to the freezer compartment 10. Furthermore, when a load is applied to the freezer compartment 10, the recovery time until the cooler compartment temperature Te returns to the temperature immediately before the freezer compartment door 15 was opened is longer than the recovery time when no load is applied.

[0077] Therefore, the adjustment coefficient calculation unit 64 measures (1) the temperature rise values ​​of the internal temperature Tf and the cooler compartment temperature Te and (2) the recovery times of the internal temperature Tf and the cooler compartment temperature Te when the freezer compartment door 15 is opened or closed. The adjustment coefficient calculation unit 64 then compares the temperature rise values ​​of the internal temperature Tf and the cooler compartment temperature Te with a threshold value (Tup1 in FIG. 9 ), and (2) compares the recovery time with a threshold time (tr in FIG. 9 ) to determine whether or not a load has been applied. The adjustment coefficient calculation unit 64 determines whether or not the load has been applied every time the freezer compartment door 15 is opened or closed during the calculation period, thereby being able to calculate the adjustment coefficient α that represents the proportion of the load applied during the calculation period.

[0078] Depending on the lifestyle of each user, there are significant differences in whether a load is frequently applied when the door is opened and closed, or whether the user only checks the inventory in the freezer compartment 10 without applying a load. Therefore, by estimating the proportion of the load applied to the freezer compartment 10 and using this as a coefficient for the usage frequency rank, it is possible to estimate the usage frequency for each user, i.e., the magnitude of the heat load on the freezer 1. Then, by performing cooling control appropriate for the estimated heat load, it is possible to improve energy saving performance and user convenience.

[0079] 10 is a flowchart showing a method for calculating the adjustment coefficient α in the first embodiment. This process is performed by the adjustment coefficient calculation unit 64 of the control device 6. First, the adjustment coefficient calculation unit 64 resets a count C1 indicating the number of determinations that a load has been applied and a count C2 indicating the number of determinations that a load has not been applied (S101). That is, the count C1 indicating the number of determinations that a load has been applied and the count C2 indicating the number of determinations that a load has not been applied are set to 0.

[0080] Next, the adjustment coefficient calculation unit 64 determines whether the temperature rise value ΔTf of the inside temperature Tf when the freezer compartment door 15 is opened or closed is equal to or greater than the first threshold value Tup1, and whether the temperature rise value ΔTe of the cooler compartment temperature Te when the freezer compartment door 15 is opened or closed is equal to or greater than the second threshold value Tup2 (S102). The temperature rise value ΔTf of the inside temperature Tf when the freezer compartment door 15 is opened or closed and the temperature rise value ΔTe of the cooler compartment temperature Te when the freezer compartment door 15 is opened or closed are measured each time the freezer compartment door 15 is opened or closed, and are stored in the storage unit 61. The first threshold value Tup1 is, for example, 10 to 12 K, and the second threshold value Tup2 is smaller than the first threshold value Tup1, for example, 8 to 10 K. The first threshold value Tup1 and the second threshold value Tup2 are merely examples, and are set appropriately depending on the insulation specifications of the freezer 1 and the specifications of the cooler 34.

[0081] Note that multiple first threshold values ​​Tup1 and second threshold values ​​Tup2 may be set for each outside air temperature Ta measured by the outside air temperature sensor 19. For example, when the outside air temperature Ta is high, the temperature rise value when the freezer compartment door 15 is opened will be larger than the temperature rise value when the freezer compartment door 15 is opened when the outside air temperature Ta is low. Therefore, by setting the first threshold value Tup1 and the second threshold value Tup2 according to the outside air temperature Ta, the accuracy of load application detection can be improved.

[0082] If at least one of the temperature increase value ΔTf of the inside temperature Tf and the temperature increase value ΔTe of the cooler compartment temperature Te is less than a threshold value (S102: NO), the adjustment coefficient calculation unit 64 determines that no load was applied during the opening / closing operation, and increments the no-load count C2 (S103). That is, if the temperature increase value ΔTf is less than the first threshold value Tup1 and the temperature increase value ΔTe is less than the second threshold value Tup2, if the temperature increase value ΔTf is equal to or greater than the first threshold value Tup1 but is less than the second threshold value Tup2, or if the temperature increase value ΔTe is equal to or greater than the second threshold value Tup2 but is less than the first threshold value Tup1, it is determined that no load was applied.

[0083] On the other hand, if the temperature rise value ΔTf of the internal temperature Tf is equal to or greater than the first threshold value Tup1 and the temperature rise value ΔTe of the cooler compartment temperature Te during the same opening and closing is equal to or greater than the second threshold value Tup2 (S102: YES), the adjustment coefficient calculation unit 64 determines whether the recovery time tf of the internal temperature Tf and the recovery time te of the cooler compartment temperature Te during the opening and closing of the freezer compartment door 15 are both equal to or greater than a predetermined threshold time tr (S104). The threshold time tr is, for example, 240 to 300 minutes. The threshold time tr is an example and is set appropriately depending on the insulation specifications of the freezer 1 and the specifications of the cooler 34.

[0084] If at least one of the recovery time tf of the inside temperature Tf and the recovery time te of the cooler compartment temperature Te is shorter than the preset threshold time tr (S104: NO), the adjustment coefficient calculation unit 64 determines that no load was applied at the time of opening or closing, and increments the no-load count C2 (S103). That is, if the recovery time tf is shorter than the threshold time tr and the recovery time te is shorter than the threshold time tr, if the recovery time tf is equal to or greater than the threshold time tr but the recovery time te is shorter than the threshold time tr, or if the recovery time te is equal to or greater than the threshold time tr but the recovery time tf is shorter than the threshold time tr, it is determined that no load was applied.

[0085] On the other hand, if the recovery time tf of the internal temperature Tf and the recovery time te of the cooler chamber temperature Te are both equal to or greater than the threshold time tr (S104: YES), the adjustment coefficient calculation unit 64 determines that a load was applied at the time of opening and closing, and counts up the load application count C1 (S105).

[0086] In step S104, the recovery time tf of the freezer compartment temperature Tf and the recovery time te of the cooler compartment temperature Te are compared with the threshold time tr, but this is not limited to this. For example, the time tfu [min / K] required for the freezer compartment temperature Tf to drop by 1 [K] after the freezer compartment door 15 is closed and the time teu [min / K] required for the cooler compartment temperature Te to drop by 1 [K] may be compared with the reference time tru [min / K]. If both the time tfu and the time teu are equal to or greater than the time tru, the adjustment coefficient calculation unit 64 may determine that a load was applied during the opening / closing and increment the load application count C1. This allows the load application determination to be made regardless of the length of time the freezer compartment door 15 is open.

[0087] Then, the adjustment coefficient calculation unit 64 determines whether the sum of the counts C1 and C2 is equal to or greater than the total number N of times the freezer compartment door 15 has been opened and closed during the calculation period (the most recent week) (S106). If the sum of the counts C1 and C2 is less than the total number N (S106: NO), the process returns to step S102, and it is determined whether a load will be applied when the door is next opened or closed during the calculation period.

[0088] If the sum of the counts C1 and C2 is equal to or greater than the total number N (S106: YES), that is, if it has been determined whether or not a load has been applied when opening and closing all of the doors during the calculation period, the adjustment coefficient calculation unit 64 calculates the adjustment coefficient α from the following equation (3) (S107): α=C1 / (C1+C2) (3)

[0089] This allows for the calculation of an adjustment coefficient α, which indicates the load application ratio when the door is opened and closed over the past week. The above calculation method uses both the internal temperature Tf and the cooler compartment temperature Te as criteria for determining whether a load is being applied, thereby improving the accuracy of estimating whether a load is being applied. The internal temperature Tf and the cooler compartment temperature Te in the freezer 1 generally follow a nearly linearly proportional relationship with a certain temperature difference ΔT (Tf - Te). Therefore, if the temperature rise values ​​and recovery times of the internal temperature Tf and the cooler compartment temperature Te are synchronized, the freezer 1 is considered to be operating normally. On the other hand, if the temperature rise values ​​and recovery times of the internal temperature Tf and the cooler compartment temperature Te are asynchronous, it is assumed that some kind of abnormality, such as an external factor or a power outage, has occurred. Therefore, if the temperature rise values ​​and recovery times of the internal temperature Tf and the cooler compartment temperature Te are asynchronous, it is determined that no load is being applied.

[0090] The determination based on the temperature rise value ΔTe of the cooler compartment temperature Te and the recovery time te is not essential and may be omitted. In this case, the temperature rise value ΔTf of the inside temperature Tf and the recovery time tf are only compared with the respective threshold values ​​to determine whether or not a load is applied.

[0091] Next, the measurement of the temperature rise value and recovery time when the door is opened and closed, which are necessary for calculating the adjustment coefficient α, will be described. Fig. 11 is a flowchart showing a method for measuring the temperature rise value and recovery time when the door is opened and closed in embodiment 1. This process is performed by the adjustment coefficient calculation unit 64 of the control device 6. First, it is determined whether the freezer compartment door 15 has been opened (S111). If the freezer compartment door 15 has not been opened (S111: NO), the process waits until the door is opened.

[0092] If the freezer compartment door 15 is opened (S111: YES), the adjustment coefficient calculation unit 64 acquires the internal temperature Tf and the cooler compartment temperature Te as the initial internal temperature Tfo and the initial cooler compartment temperature Teo (S112). The initial internal temperature Tfo and the initial cooler compartment temperature Teo are the internal temperature Tf and the cooler compartment temperature Te at the time when the opening of the freezer compartment door 15 is detected by the opening / closing sensor 17 and an opening signal is received, and are substantially the same as the internal temperature Tf and the cooler compartment temperature Te immediately before the freezer compartment door 15 is opened. Then, measurement of the temperature rise time tup of the internal temperature Tf and the cooler compartment temperature Te is started (S113).

[0093] Next, it is determined whether the freezer compartment door 15 is closed (S114). If the freezer compartment door 15 is not closed (S114: NO), the process waits until the freezer compartment door 15 is closed. Then, when the freezer compartment door 15 is closed (S114: YES), the adjustment coefficient calculation unit 64 acquires the inside temperature Tf1 and the cooler compartment temperature Te1 at time t1 (S115).

[0094] The adjustment coefficient calculation unit 64 waits for a time Δt1 (S116), and acquires the inside temperature Tf2 and the cooler compartment temperature Te2 at time t+Δt1 (S117). Then, the adjustment coefficient calculation unit 64 calculates the temperature gradient Sf of the inside temperature Tf and the temperature gradient Se of the cooler compartment temperature Te from the following equations (4) and (5) (S118). Sf=(Tf2-Tf1) / Δt1 (4) Se=(Te2-Te1) / Δt1 (5)

[0095] The adjustment coefficient calculation unit 64 then simultaneously checks the temperature rise changes in the internal temperature Tf and the cooler compartment temperature Te. First, the internal temperature Tf will be described. The adjustment coefficient calculation unit 64 determines whether the temperature gradient Sf of the internal temperature Tf is greater than 0 and whether the freezer compartment door 15 is closed (S119). If the temperature gradient Sf of the internal temperature Tf is greater than 0 and the freezer compartment door 15 is closed (S119: YES), it determines that the internal temperature Tf has not yet finished rising and continues to rise, and returns to step S115, where the processes of steps S115 to S118 are repeated to calculate the most recent temperature gradient Sf.

[0096] On the other hand, if the temperature gradient Sf of the internal temperature Tf is equal to or less than 0, or if the freezer door 15 is opened again (S119: NO), it is determined that the rise in the internal temperature Tf has reached its peak value, and the internal temperature Tf at this time is acquired as the peak internal temperature Tfmax (S120). Then, the initial internal temperature Tfo acquired in step S112 is subtracted from the peak internal temperature Tfmax acquired in step S120 to calculate the temperature rise value ΔTf of the internal temperature Tf (S121).

[0097] Next, the cooler compartment temperature Te will be described. The adjustment coefficient calculation unit 64 determines whether the temperature gradient Se of the cooler compartment temperature Te is greater than 0 and whether the freezer compartment door 15 is closed (S122). If the temperature gradient Sf of the cooler compartment temperature Te is greater than 0 and the freezer compartment door 15 is closed (S122: YES), it is determined that the cooler compartment temperature Te has not yet finished rising and continues to rise, and the process returns to step S115, where the processes of steps S115 to S118 are repeated to calculate the most recent temperature gradient Se.

[0098] On the other hand, if the temperature gradient Se of the cooler compartment temperature Te is equal to or less than 0, or if the freezer compartment door 15 is opened again (S122: NO), it is determined that the rise in the cooler compartment temperature Te has reached its peak value, and the cooler compartment temperature Te at this time is acquired as the peak cooler compartment temperature Temax (S123).Then, the initial cooler compartment temperature Teo acquired in step S112 is subtracted from the peak cooler compartment temperature Temax acquired in step S123 to calculate the temperature rise value ΔTe of the cooler compartment temperature Te (S124).

[0099] This makes it possible to determine the temperature rise value ΔTf of the inside temperature Tf and the temperature rise value ΔTe of the cooler compartment temperature Te each time the freezer compartment door 15 is opened or closed. The determined temperature rise value ΔTf of the inside temperature Tf and the temperature rise value ΔTe of the cooler compartment temperature Te are stored in the memory unit 61 together with the date and time.

[0100] Next, a method for measuring the recovery time when the door is opened and closed will be described. FIG. 12 is a flowchart showing a method for measuring the recovery time when the door is opened and closed in the first embodiment. This process is performed by the adjustment coefficient calculation unit 64 of the control device 6 in parallel with the calculation of the temperature rise value. First, it is determined whether the freezer compartment door 15 has been opened (S131). If the freezer compartment door 15 has not been opened (S131: NO), the process waits until the freezer compartment door 15 is opened. If the freezer compartment door 15 has been opened (S131: YES), it is determined whether the freezer compartment door 15 has been closed (S132). If the freezer compartment door 15 has not been closed (S132: NO), the process waits until the freezer compartment door 15 is closed.

[0101] If the freezer compartment door 15 is closed (S132: NO), the adjustment coefficient calculation unit 64 starts measuring the recovery times tf and te (S133). After that, the unit waits for a time Δt2 (S134) and acquires the internal temperature Tf and the cooler compartment temperature Te (S135). Then, the unit checks whether the internal temperature Tf and the cooler compartment temperature Te have returned to the initial internal temperature Tfo and the initial cooler compartment temperature Teo, respectively.

[0102] First, the internal temperature Tf will be described. The adjustment coefficient calculation unit 64 determines whether the internal temperature Tf is equal to or lower than the initial internal temperature Tfo (S136). If the internal temperature Tf is higher than the initial internal temperature Tfo (S136: NO), the process returns to step S134, where the internal temperature Tf is acquired every time Δt2, and the adjustment coefficient calculation unit 64 determines whether the internal temperature Tf has returned to the initial internal temperature Tfo. If the internal temperature Tf is equal to or lower than the initial internal temperature Tfo (S136: YES), the adjustment coefficient calculation unit 64 determines that the internal temperature Tf has returned to the temperature before the freezer door 15 was opened, and acquires the time at which this occurs as the recovery time tf (S137).

[0103] Next, the cooler compartment temperature Te will be described. The adjustment coefficient calculation unit 64 determines whether the cooler compartment temperature Te is equal to or lower than the initial cooler compartment temperature Teo (S138). If the cooler compartment temperature Te is higher than the initial cooler compartment temperature Teo (S138: NO), the process returns to step S134, where the cooler compartment temperature Te is acquired every time Δt2, and a determination is made as to whether the cooler compartment temperature Teo has returned to the initial cooler compartment temperature Teo. If the cooler compartment temperature Te becomes equal to or lower than the initial cooler compartment temperature Teo (S138: YES), the adjustment coefficient calculation unit 64 determines that the cooler compartment temperature Te has returned to the initial cooler compartment temperature Teo, and acquires the time at which this occurs as the return time te (S139).

[0104] This makes it possible to determine the recovery time tf of the inside temperature Tf and the recovery time te of the cooler compartment temperature Te each time the freezer compartment door 15 is opened or closed. The determined recovery time tf of the inside temperature Tf and the recovery time te of the cooler compartment temperature Te are stored in the memory unit 61 together with the date and time.

[0105] Next, the normal operation and suppression operation performed in steps S4 and S5 of Fig. 8 will be described. Fig. 13 is a diagram illustrating the suppression operation of the freezer 1 according to embodiment 1. Fig. 13 shows the change over time in electric power [W], the operation (ON) and stop (OFF) of the compressor 31 and the blower 35, the change over time in the internal temperature Tf and the cooler compartment temperature Te, and the change over time in the temperature difference ΔT between the internal temperature Tf and the cooler compartment temperature Te.

[0106] 13, during normal operation, the compressor 31 and the blower 35 are operated or stopped in synchronization, and therefore the waveforms of the compressor 31, the blower 35, and the power are rectangular waves that indicate synchronized operation or stopping. The synchronized operation of the compressor 31 and the blower 35 controls the inside temperature Tf of the freezer compartment 10 to be within the allowable range of the set temperature Tfs.

[0107] The specific control of the refrigerator compartment temperature Tf is the same as that described with reference to FIG. 9 . The control of the refrigerator compartment temperature Te is the same as the control of the refrigerator compartment temperature Tf. In normal operation, the cooling control unit 62 synchronizes the compressor 31 and the blower 35 and switches them on and off so that the refrigerator compartment temperature Te falls within the allowable range Tes±dθe, with the set temperature Tes as the target value. The allowable range dθe varies depending on the insulation specifications of the freezer 1 and the specifications of the cooler 34, but is, for example, 2 to 4 K. This maintains the average value of the cooler compartment temperature Te at the set temperature Tes. In reality, as the cooler 34 cools, cold air circulates within the freezer compartment 10. Therefore, although there is a slight time lag, the temperature in the cooler compartment 3 changes first, followed by the temperature change in the freezer compartment 10.

[0108] Because the internal temperature Tf and the cooler compartment temperature Te are controlled as described above, a constant temperature difference ΔT = Tf - Te is basically maintained between the freezer compartment 10 and the cooler compartment 3. This temperature difference ΔT between the freezer compartment 10 and the cooler compartment 3 varies depending on the insulation specifications of the freezer 1 or the specifications of the cooler 34, but is often in the range of approximately 3 to 5 [K].

[0109] Next, the suppression operation will be described. As described above, during normal operation, a certain temperature difference ΔT occurs between the internal temperature Tf and the cooler compartment temperature Te. In other words, when viewed from the freezer compartment 10, the cooler compartment 3 is relatively colder, so by using the remaining cold air in the cooler compartment 3, cooling is possible for a certain period of time without the need to drive the compressor 31 to cool the cooler 34 again.

[0110] Therefore, in the freezer 1 of this embodiment, as a suppression operation, the compressor 31 is stopped and only the blower 35 is operated, and the remaining cold air in the cooler chamber 3 is used to cool the freezer chamber 10. In normal operation, cooling the freezer chamber 10 requires power to drive the compressor 31 and the blower 35 and operate both the compressor 31 and the blower 35, but by performing the suppression operation, the power required to operate the compressor 31 can be temporarily suppressed. In Figure 13, the amount of power that can be suppressed is shown as a hatched area AR.

[0111] When performing suppression operation, the temperature difference ΔT between the cooler compartment 3 and the freezer compartment 10 must be equal to or greater than a certain value in order for the remaining cold air in the cooler compartment 3 to be used to cool the freezer compartment 10. Therefore, when the temperature difference ΔT = Te - Tf between the cooler compartment 3 and the freezer compartment 10 becomes less than the threshold value Tth, the cooling control unit 62 ends the suppression operation and drives both the compressor 31 and the blower 35 to cool the freezer compartment 10. The threshold value Tth used to determine the end of the suppression operation varies depending on the insulation specifications of the freezer 1 and the specifications of the cooler 34 and the compressor 31, but is, for example, 1.0 [K].

[0112] Furthermore, the cooling control unit 62 determines whether to perform suppression operation only when the usage frequency rank for the current time period is the lowest FR1, i.e., only during non-use time periods. This is because it can be determined that external factors attributable to the user are less likely to cause changes in the temperature of the freezer compartment 10 during non-use time periods. In other words, during non-use time periods, the frequency of opening and closing the freezer compartment door 15 and the frequency of load application to the freezer compartment 10 are low, so it is considered that only the thermal load of the items already stored in the freezer compartment 10 needs to be considered.

[0113] 14 is a flowchart showing the flow of normal operation in the freezer 1 according to the first embodiment. This process is performed by the cooling control unit 62 of the control device 6. At the start of this process, the compressor 31 and the blower 35 are assumed to be stopped. The cooling control unit 62 determines whether the internal temperature Tf is less than the lower limit (Tfs-dθf) of the allowable range of the set temperature Tfs (S41).

[0114] If the internal temperature Tf is equal to or higher than the lower limit (Tfs-dθf) of the allowable range of the set temperature Tfs (NO in S41), the cooling control unit 62 determines that the internal temperature Tf is within the allowable range of the set temperature Tfs and operates the compressor 31 and the blower 35 (S42). Then, the process returns to step S41. On the other hand, if the internal temperature Tf is lower than the lower limit (Tfs-dθf) of the allowable range of the set temperature Tfs (YES in S41), the cooling control unit 62 determines that the freezer compartment 10 has been cooled to a temperature equal to or higher than the target temperature range and stops the compressor 31 and the blower 35 (S43), temporarily suspending the cooling of the freezer compartment 10.

[0115] The cooling control unit 62 then determines whether the internal temperature Tf is higher than the upper limit (Tfs + dθf) of the allowable range of the set temperature Tfs (S44). If the internal temperature Tf is equal to or lower than the upper limit (Tfs + dθf) of the allowable range of the set temperature Tfs (S44: NO), the cooling control unit 62 determines that the internal temperature Tf is within the allowable range of the set temperature Tfs, and continues to temporarily suspend cooling while keeping the compressor 31 and the blower 35 stopped.

[0116] On the other hand, if the internal temperature Tf is higher than the upper limit (Tfs + dθf) of the allowable range of the set temperature Tfs (S44: YES), the cooling control unit 62 determines that the temperature of the freezer compartment 10 is higher than the target temperature range, and operates the compressor 31 and the blower 35 (S45), thereby restarting cooling of the freezer compartment 10. Thereafter, the process returns to step S41, and the subsequent processes are repeated. This allows the control device 6 to control the compressor 31 and the blower 35 so that the average internal temperature Tf approaches the target set temperature Tfs.

[0117] FIG. 15 is a flowchart showing the flow of suppression operation in the freezer 1 according to the first embodiment. This process is performed by the cooling control unit 62 of the control device 6. At the start of this process, the compressor 31 and the blower 35 are assumed to be stopped. First, the cooling control unit 62 determines whether the temperature difference ΔT between the internal temperature Tf and the cooler compartment temperature Te is equal to or greater than the threshold value Tth (S51). If the temperature difference ΔT between the internal temperature Tf and the cooler compartment temperature Te is less than the threshold value Tth (S51: NO), the cooling control unit 62 determines that the temperature difference between the cooler compartment 3 and the freezer compartment 10 is small and therefore the remaining cold air in the cooler compartment 3 is not sufficient to continue cooling the freezer compartment 10. The cooling control unit 62 then terminates the suppression operation and transitions to normal operation.

[0118] On the other hand, if the temperature difference ΔT between the internal temperature Tf and the cooler compartment temperature Te is equal to or greater than the threshold value Tth (S51: YES), the cooling control unit 62 determines whether the internal temperature Tf is higher than the upper limit (Tfs + dθf) of the allowable range of the set temperature Tfs (S52). If the internal temperature Tf is equal to or lower than the upper limit (Tfs + dθf) of the allowable range of the set temperature Tfs (S52: NO), the cooling control unit 62 determines that the internal temperature Tf is within the allowable range of the set temperature Tfs, and waits with the compressor 31 and the blower 35 stopped.

[0119] On the other hand, if the internal temperature Tf is higher than the upper limit (Tfs + dθf) of the allowable range of the set temperature Tfs (S52: YES), the cooling control unit 62 determines that the temperature of the freezer compartment 10 is higher than the target temperature range, and operates only the blower 35 while keeping the compressor 31 stopped (S53). At this time, the rotation speed of the blower 35 is set to the minimum rotation speed. As a result, the cool air in the cooler compartment 3 is sent by the blower 35 to the freezer compartment 10, cooling the freezer compartment 10.

[0120] The cooling control unit 62 acquires the internal temperature Tf1 at time t (S54). Then, the cooling control unit 62 waits for a time Δt3 (S55) and acquires the internal temperature Tf2 at time t + Δt3 (S56). The cooling control unit 62 then determines whether the temperature difference ΔT between the internal temperature Tf and the cooler compartment temperature Te is equal to or greater than the threshold value Tth (S57). If the temperature difference ΔT between the internal temperature Tf and the cooler compartment temperature Te is less than the threshold value Tth (S57: NO), the cooling control unit 62 determines that the temperature difference between the cooler compartment 3 and the freezer compartment 10 is small and therefore the remaining cold air in the cooler compartment 3 is insufficient to continue cooling the freezer compartment 10. The cooling control unit 62 then terminates the suppression operation and transitions to normal operation. On the other hand, if the temperature difference ΔT between the internal temperature Tf and the cooler compartment temperature Te is equal to or greater than the threshold value Tth (S57: YES), the cooling control unit 62 calculates the absolute value of the temperature gradient Sf of the internal temperature Tf using the following equation (6) (S58). |Sf|=(Tf2-Tf1) / Δt3...(6)

[0121] Next, the cooling control unit 62 determines whether the absolute value of the temperature gradient |Sf| is equal to or greater than the absolute value of the previous temperature gradient |Sf| (S59). If the temperature gradient |Sf| is equal to or greater than the previous temperature gradient |Sf| (S59: YES), the process returns to step S54 and repeats the subsequent processes. Note that even when the temperature gradient |Sf| is calculated for the first time, there is no previous temperature gradient |Sf|, so the determination in step S58 is YES and the process returns to step S54. On the other hand, if the temperature gradient |Sf| is less than the previous temperature gradient |Sf| (S59: NO), the cooling control unit 62 increases the rotation speed of the blower 35 (S60).

[0122] The cooling control unit 62 then determines whether the internal temperature Tf is below the lower limit (Tfs-dθf) of the allowable range of the set temperature Tfs (S61). If the internal temperature Tf is equal to or higher than the lower limit (Tfs-dθf) of the allowable range of the set temperature Tfs (S61: NO), the cooling control unit 62 determines that the internal temperature Tf is within the allowable range of the set temperature Tfs and continues operating the blower 35. Then, the process returns to step S52 and the subsequent processes are repeated.

[0123] On the other hand, if the internal temperature Tf is less than the lower limit (Tfs-dθf) of the allowable range of the set temperature Tfs (S61: YES), the cooling control unit 62 determines that the freezer compartment 10 has been cooled to a temperature equal to or higher than the target temperature range, stops the blower 35 (S62), and temporarily suspends the cooling of the freezer compartment 10. Thereafter, the process returns to step S51 and the subsequent processes are repeated.

[0124] If the current temperature gradient |Sf| is less than the temperature gradient |Sf| confirmed at the previous timing, it is considered that the efficiency of heat exchange between the remaining cold air in the cooler compartment 3 and the freezer compartment 10 is decreasing. Therefore, the cooling control unit 62 increases the rotation speed of the blower 35 to further promote heat exchange between the cooler compartment 3 and the freezer compartment 10. Here, the increase in rotation speed is, for example, around 200 to 300 rpm. Furthermore, the speed of the blower 35 in this embodiment can be set in the range of approximately 1200 to 2300 rpm.

[0125] During suppression operation, the initial rotation speed of the fan 35 is set to the minimum rotation speed and operation of the fan 35 is started. Then, based on the inside temperature Tf, the temperature gradient |Sf| of the inside temperature Tf is repeatedly calculated at regular time intervals (Δt3), and the rotation speed of the fan 35 is increased each time the latest temperature gradient |Sf| becomes less than the previous temperature gradient |Sf|. In this way, the rotation speed of the fan 35 is controlled in stages from a low rotation speed to a high rotation speed.

[0126] Generally, if the blower 35 is operated at the maximum rotation speed from the beginning, convection within the cooler chamber 3 will be rapid, preventing maximum efficiency of heat exchange between the air within the cooler chamber 3 and the freezer chamber 10. This is because the high flow rate of the convected air also increases the flow rate of the air on the wall side of the cooler chamber 3, promoting heat exchange between the air and the wall of the cooler chamber 3. In contrast, as described above, by controlling the rotation speed of the blower 35 so that it gradually increases from a low rotation speed during suppression operation, it is possible to suppress a decrease in heat exchange efficiency and reduce power consumption of the blower 35.

[0127] Furthermore, if the fan 35 is operated at a high rotation speed when cooling the freezer compartment 10, a sudden noise may be emitted from the freezer 1, which may cause discomfort to the user. In contrast, by gradually increasing the rotation speed of the fan 35 at regular time intervals as described above, the user is less likely to feel that the operating noise of the fan 35 has suddenly increased, which can reduce discomfort.

[0128] As described above, in the freezer 1 of this embodiment, when the temperature difference ΔT between the cooler compartment 3 and the freezer compartment 10 is equal to or greater than the threshold value Tth during non-use periods, the operation of the compressor 31 is temporarily stopped and only the blower 35 is operated. This allows the freezer compartment 10 to be cooled using the remaining cold air in the cooler compartment 3, thereby reducing the power consumed by the operation of the compressor 31 during suppression operation.

[0129] Fig. 16 is a ph diagram showing the effect obtained by performing suppression operation in the freezer 1 according to the first embodiment. In Fig. 16, the dashed line indicates the refrigeration cycle during normal operation, and the solid line indicates the refrigeration cycle during suppression operation. In the freezer 1 according to the present embodiment, by performing suppression operation, the inside of the freezer compartment 10 is cooled with the residual cold air in the cooler compartment 3 and then the compressor 31 is driven to perform cooling, thereby reducing the thermal load on the compressor 31 and the cooler 34 compared to when suppression operation is not performed.

[0130] 16, the workload Wcomp of the compressor 31 generated in the compression process for compressing the refrigerant is reduced, and the workload of the compressor 31 can be reduced by ΔWcomp. As a result, the power consumption required to operate the compressor 31 can be reduced, and energy-saving performance can be improved.

[0131] Embodiment 2. Embodiment 2 will be described. The freezer 1 of embodiment 2 differs from embodiment 1 in that the set temperature Tfs of the freezer 1 is varied depending on the usage frequency rank. The configuration of the freezer 1 in embodiment 2 is the same as that of embodiment 1, and the following description will focus on the differences.

[0132] 17 is a flowchart showing the operation of the freezer 1 according to the second embodiment. First, the rank determination unit 65 of the control device 6 calculates an adjustment coefficient α (S201). The calculation method of the adjustment coefficient α is the same as in the first embodiment. Then, the rank determination unit 65 determines a usage frequency rank for each time slot of the day (S202). As in the first embodiment, the usage frequency rank is determined based on the discrimination parameter X obtained by multiplying the adjustment coefficient α by the average number of times the door is opened and closed in the most recent week and the average duration of time the door is open.

[0133] The cooling control unit 62 then sets a set temperature Tfs for the freezer 1's internal temperature Tf according to the usage frequency rank of the current time period (S203). First, if the usage frequency rank is FR1 (S203:FR1), that is, if the current time period corresponds to a non-use time period, the cooling control unit 62 sets the set temperature Tfs to a first reference temperature T1 (S204). The first reference temperature T1 is, for example, -18°C.

[0134] If the usage frequency rank is FR2 or FR3 (S203: FR2 or FR3), that is, if the time corresponds to a time period with low usage frequency, the cooling control unit 62 sets the set temperature Tfs to a second reference temperature T2 (S205). The second reference temperature T2 is lower than the first reference temperature T1, for example, −19° C.

[0135] If the usage frequency rank is FR4 or FR5 (S203: FR4 or FR5), i.e., if the time corresponds to a time period with high usage frequency, the cooling control unit 62 sets the set temperature Tfs to a third reference temperature T3 (S206). The third reference temperature T3 is lower than the second reference temperature T2, for example, -20°C. The subsequent steps S207 to S209 are the same as steps S3 to S5 in the first embodiment. After S209, the process returns to step S203, and steps S203 to S209 are repeated for each time period.

[0136] FIG. 18 is an example of a graph showing changes in the number of times the freezer compartment door 15 is opened and closed, the use frequency rank, and the set temperature Tfs of the freezer compartment 10 in the freezer 1 according to embodiment 2. The first row from the top of FIG. 18 shows the results of detecting whether the freezer compartment door 15 is open or closed on the current day, and the second row from the top shows the trend in the number of times the freezer compartment door 15 is opened and closed in each time period (one hour), averaged over the past week excluding the current day. The third row from the top shows the use frequency rank calculated from the discrimination parameter X (= adjustment coefficient α × number of times the door is opened × door open time) for each time period. The fourth row from the top shows the trend in the set temperature Tfs of the freezer compartment 10 when each time period is classified into three categories based on the use frequency rank: unused, low use frequency, and high use frequency.

[0137] By categorizing the usage frequency ranks into three categories, not in use, low frequency of use, and high frequency of use, the time periods and magnitudes of the thermal load on the freezer compartment 10 can be classified into three types. Then, by varying the set temperature Tfs of the freezer compartment 10 according to the usage frequency, the freezer compartment 10 can be set to cool down during times when the user's usage frequency is high, thereby suppressing the temperature rise of the items stored in the freezer compartment 10. Furthermore, during times when the user's usage frequency is low, excessive cooling can be suppressed, reducing the workload of the compressor 31 and thus power consumption. This further improves the energy-saving performance of the freezer 1.

[0138] Embodiment 3. Embodiment 3 will be described. The freezer 1 of embodiment 3 differs from embodiment 1 in that the settings of the compressor 31 and the blower 35 of the freezer 1 are changed using the usage frequency rank and the outside air rank. The configuration of the freezer 1 in embodiment 3 is the same as that of embodiment 1, and the following description will focus on the differences.

[0139] 19 is a flowchart showing the operation of the freezer 1 according to the third embodiment. First, the rank determination unit 65 of the control device 6 calculates an adjustment coefficient α (S301). The calculation method of the adjustment coefficient α is the same as in the first embodiment. Then, the rank determination unit 65 determines a usage frequency rank for each time slot of the day (S302). As in the first embodiment, the usage frequency rank is determined based on the adjustment coefficient α and the discrimination parameter X, which is the product of the average number of times the freezer compartment door 15 is opened and closed over the past week and the average duration for which the door is open.

[0140] Then, the rank determination unit 65 determines the outdoor air rank for the current time period based on the outdoor air temperature Ta measured by the outdoor air temperature sensor 19 (S303). As an example, the rank determination unit 65 classifies the outdoor air rank for each time period into six levels AR1 to AR6 according to the outdoor air temperature Ta as follows: 1) Outdoor air rank AR1: Ta<12°C 2) Outdoor air rank AR2: 12°C≦Ta<18°C 3) Outdoor air rank AR3: 18°C≦Ta<22°C 4) Outdoor air rank AR4: 22°C≦Ta<28°C 5) Outdoor air rank AR5: 28°C≦Ta<36°C 6) Outdoor air rank AR6: 36°C≦Ta

[0141] Next, the rank determination unit 65 determines a set rank based on the usage frequency rank for the current time period and the outdoor air rank (S304). Fig. 20 is an example of a table showing set ranks according to the usage frequency rank and the outdoor air rank of the freezer 1 according to embodiment 3. The table of Fig. 20 is stored in the storage unit 61 of the freezer 1. As shown in Fig. 20, five set ranks, SR1 to SR5, are determined according to the usage frequency rank and the outdoor air rank.

[0142] 20 , the rank determination unit 65 basically determines that the higher the outdoor air rank, the greater the outdoor heat load, and sets a higher rank. Similarly, the rank determination unit 65 determines that the higher the usage frequency rank, the greater the input heat load, and sets a higher rank. This allows the refrigeration capacity to be increased when the outdoor air rank and usage frequency rank are high.

[0143] In Fig. 20, the set ranks are set to five levels, but the rank classification is not limited to this. For example, the set ranks may be classified more finely, such as 1 to 30 levels. Furthermore, the use frequency rank and the outdoor air rank are not limited to the example in Fig. 20, and may be classified more finely, such as 1 to 30 levels, or more roughly, such as 1 to 3 levels. Regarding the rank classification, the finer the levels, the more memory space is required, so it is recommended to classify the ranks according to the memory space to be used.

[0144] Returning to FIG. 19 , once the rank determination unit 65 has determined the set rank, the cooling control unit 62 sets the basic rotation speeds of the compressor 31 and the blower 35 based on the determined set rank (S305). The cooling control unit 62 sets the basic rotation speeds of the compressor 31 and the blower 35 according to the set rank so that the rotation speeds of the compressor 31 and the blower 35 are lowest for the set rank SR1 and highest for the set rank SR2. Note that only the rotation speed of the compressor 31 may be set according to the set rank, while the rotation speed of the blower 35 may be kept constant. Subsequent steps S306 to S308 are the same as steps S3 to S5 in the first embodiment. After step S308, the process returns to step S303, and steps S303 to S308 are repeated for each time period.

[0145] Fig. 21 is an example of a graph showing the number of times the freezer compartment door 15 is opened and closed, the usage frequency rank, and the set rank in the freezer 1 according to embodiment 3. The first, second, and third rows from the top of Fig. 21 are the same as Fig. 18 of embodiment 2. The fourth row from the top of Fig. 21 is the set rank determined based on the usage frequency rank and the outside air rank. The set rank corresponds to the change in the rotation speed of the compressor 31 when the compressor 31 is operating at a refrigeration capacity appropriate for the usage frequency rank.

[0146] By classifying the usage frequency rank into three categories, namely, not in use, low usage frequency, and high usage frequency, it is possible to classify the time periods and magnitudes of the thermal load on the freezer compartment 10 into three categories. Then, it is possible to set the basic rotation speeds of the compressor 31 and the blower 35 appropriate for each usage frequency, thereby enabling operation appropriate for the expected thermal load.

[0147] Furthermore, the setting rank is determined not only based on the frequency of use but also on the outside air temperature Ta, which is the temperature of the space in which the freezer 1 is installed, and the rotation speeds of the compressor 31 and the blower 35 are varied. This allows the workload of the compressor 31 and the blower 35 to be optimized according to the usage status of the freezer 1, and allows cooling of the freezer compartment 10 while suppressing power consumption.

[0148] The thermal load on the cooler 34 of the freezer 1 is a combination of the external thermal load caused by heat intrusion from the external space outside the freezer 1, and the input thermal load generated by the intrusion of outside air through the freezer compartment door 15 when the user opens and closes the door, and the stored item load. For this reason, in the cooling operation of the freezer 1, it is necessary to calculate the load amounts of the external thermal load and the input thermal load, and perform cooling with a refrigeration capacity that matches the load expected to be applied to the cooler 34. When a load is applied, the internal temperature Tf rises, and the cooler 34 is also subjected to a load to eliminate the temperature rise.

[0149] In the freezer 1 of this embodiment, the degree of external heat load is determined from the outdoor air rank, and the degree of input heat load is determined from the usage frequency rank. The freezer 1 estimates the refrigeration capacity required to cool the freezer compartment 10 during normal operation. The final refrigeration capacity is determined by the combination of the insulation specifications of the freezer 1, the specifications of the cooler 34, and the specifications of the compressor 31. That is, the insulation specifications significantly affect the external heat load, the specifications of the cooler 34 are determined by the total amount of heat ingress from the outside air and the heat load of the food placed in the freezer compartment 10, and the specifications of the compressor 31 affect the maximum refrigeration capacity. Because the insulation specifications, the specifications of the cooler 34, and the specifications of the compressor 31 are determined during the design of the freezer 1, target refrigeration capacities for each outdoor air rank and usage frequency rank can be determined in advance through experiments or the like and stored in the memory unit 61. This further improves the energy-saving performance of the freezer 1.

[0150] Embodiment 4. Embodiment 4 will be described. The freezer 1 of embodiment 4 differs from embodiment 1 in that a defrosting operation is performed during non-use periods. The configuration of the freezer 1 in embodiment 4 is the same as that of embodiment 1, and the following description will focus on the differences.

[0151] First, a general defrosting operation of the freezer 1 will be described. The cooling control unit 62 transitions from normal operation to defrosting operation when the continuous operation time of the compressor 31 reaches or exceeds a first judgment time, or when the cumulative operation time since the end of the previous defrosting operation of the compressor 31 reaches a second judgment time. The first judgment time is a time determined in advance through experiments or the like, and is a time when it is considered highly likely that frost has formed on the cooler 34. Similarly, the second judgment time is a time determined in advance through experiments or the like, and is a time when it is considered highly likely that frost has formed on the cooler 34. These judgment times vary depending on the insulation specifications of the freezer 1 and the specifications of the cooler 34, but for example, the first judgment time is 12 to 24 hours, and the second judgment time is 24 to 72 hours.

[0152] Next, the special defrosting operation of this embodiment will be described. Generally, a greater force is required to open the freezer compartment door 15 of the freezer 1 than to open the refrigerator compartment door of a refrigerator. This is because the temperature inside the freezer compartment 10 is much lower than the temperature of the space outside the freezer 1, and therefore the freezer compartment 10 is under negative pressure when viewed from the space outside the freezer 1.

[0153] Generally, when the pressure of a gas is P, the volume is V, the amount of substance is n, and the temperature is T, the following equation (7) holds: PV=nRT (7)

[0154] Here, R is a proportionality constant called the gas constant, and its value changes depending on the unit of volume or atmospheric pressure. From the above equation (7), P = nRT / V, and the lower the temperature T (the colder it is), the lower the gas pressure.

[0155] Another reason why the freezer compartment 10 becomes a large negative pressure relative to the space outside the freezer 1 is that the freezer compartment 10 is well sealed, making it impossible to eliminate the pressure difference with the outside. The freezer 1 of this embodiment has a gas path (not shown) that connects the freezer compartment 10 to the space outside the freezer 1, and is configured to be able to balance the pressure with the space outside the freezer 1 through the drain pipe 42 so that the freezer compartment 10 does not become sealed. However, if the drain pipe 42 is blocked, the pressure balance between the freezer compartment 10 and the space outside the freezer 1 cannot be achieved, making it impossible to reduce the relative negative pressure value inside the freezer compartment 10.

[0156] Therefore, the freezer 1 of this embodiment performs a special defrosting operation and operates the drain heater 43 before the timing when the user is likely to open or close the door. This prevents the drain pipe 42 from closing, and balances the pressure between the freezer compartment 10 and the space outside the freezer 1. As a result, the relative negative pressure value in the freezer compartment 10 decreases, and it becomes possible to reduce the force required to open and close the door of the freezer 1.

[0157] 22 is a flowchart showing the operation of the freezer 1 according to the fourth embodiment. First, the rank determination unit 65 of the control device 6 calculates the adjustment coefficient α (S401). Then, the rank determination unit 65 determines the usage frequency rank for each time slot of the day (S402). The calculation method of the adjustment coefficient α and the determination method of the usage frequency rank are the same as those in the first embodiment.

[0158] The determination unit 66 determines whether the usage frequency rank for the current time period corresponds to a non-use time period (S403). If the usage frequency rank for the current time period is the lowest rank FR1, the determination unit 66 determines that the time period is a non-use time period. If the usage frequency rank does not correspond to a non-use time period (S403: NO), the determination unit 66 determines that the special defrosting operation will not be performed, and normal operation is performed (S404).

[0159] On the other hand, if the usage frequency rank corresponds to the non-use time period (S403: YES), that is, if the usage frequency rank is FR1, the determination unit 66 determines to perform the special defrosting operation, and the special defrosting operation is performed (S405). Thereafter, the process returns to step S403, and the normal operation or the special defrosting operation is performed for each time period.

[0160] In the special defrosting operation of this embodiment, the end threshold temperature T_end is varied with reference to the outside air temperature Ta, and the defrost heater 41 and the drain heater 43 are operated in synchronization. FIG. 23 is a flowchart showing the flow of the special defrosting operation of the freezer 1 according to embodiment 4. This process is performed by the heater control unit 63. First, the heater control unit 63 checks the remaining time tz of the non-use time slot (S501) and determines whether the remaining time tz of the non-use time slot is equal to or less than the end threshold time t_end (S502). The remaining time tz of the non-use time slot can be confirmed from the current time and the end time of the non-use time slot adjacent to the current time slot. The end threshold time t_end is the time for which the special defrosting operation is performed, and is, for example, 5 to 10 minutes.

[0161] If the remaining time tz of the non-use time period is greater than the end threshold time t_end (S502: NO), the process returns to step S501, and the process repeats the determination of whether the remaining time tz of the non-use time period is equal to or less than the end threshold time t_end. If the remaining time tz of the non-use time period is equal to or less than the end threshold time t_end (S502: YES), the outside air temperature Ta measured by the outside air temperature sensor 19 is acquired (S503).

[0162] The heater control unit 63 then determines whether the outside air temperature Ta is lower than the end threshold temperature T_end (step S504). If the outside air temperature Ta is lower than the end threshold temperature T_end (S504: YES), the heater control unit 63 sets the outside air temperature Ta to the end threshold temperature T_end (S505). The heater control unit 63 then synchronizes the defrost heater 41 and the drain heater 43, energizes them, and operates them (S506). On the other hand, if the outside air temperature Ta is equal to or higher than the end threshold temperature T_end (S504: NO), the heater control unit 63 operates the defrost heater 41 and the drain heater 43 without changing the end threshold temperature T_end (S506).

[0163] Then, the heater control unit 63 acquires the cooler compartment temperature Te at time t (S507). Then, the heater control unit 63 waits for time Δt4 (S508) and determines whether or not the cooler compartment temperature Te is equal to or higher than the end threshold temperature T_end (S509). Here, the number of determinations in step S509 may be counted. By counting the number of determinations, the defrosting operation time with the defrost heater 41 energized can be determined.

[0164] If the cooler compartment temperature Te is lower than the end threshold temperature T_end (S509: NO), the heater control unit 63 returns to step S507 and repeats the subsequent processes. On the other hand, if the cooler compartment temperature Te is equal to or higher than the end threshold temperature T_end (S509: YES), the heater control unit 63 stops the defrost heater 41 and the drain heater 43 (S510) and ends the special defrosting operation.

[0165] The time Δt4 is set as short as possible, between about 1 and 5 seconds. By setting the time Δt4 as short as possible, the time for which the defrost heater 41 is energized can be shortened, thereby reducing power consumption. In other words, the amount of heat from the defrost heater 41 causes the cooler compartment temperature Te to rise, but it is desirable that the amount by which the cooler compartment temperature Te exceeds the end threshold temperature T_end be as small as possible. In other words, it is desirable to prevent the cooler compartment temperature Te from becoming significantly higher than the end threshold temperature T_end.

[0166] Next, using Figures 24 to 26, a comparison will be made between a case in which the termination threshold temperature T_end of the defrosting operation in embodiment 4 is not varied with reference to the outside air temperature Ta and a case in which it is varied. Figure 24 is a diagram for explaining the electrical input and cooler compartment temperature of the defrosting operation in a conventional freezer at low outside air temperatures. Figure 25 is a diagram for explaining the electrical input and cooler compartment temperature of the defrosting operation in a freezer 1 according to embodiment 4 at low outside air temperatures. Figure 26 is a diagram for comparing the length of heater energization time between a conventional freezer and the freezer 1 according to embodiment 4.

[0167] The conventional example in Fig. 24 shows a case where the outside air temperature is 10°C and the termination threshold temperature is fixed at 16°C. As shown in Fig. 24, during the heater energization period, the gradient of the rise in the cooler compartment temperature Te suddenly becomes gentler in the period when the cooler compartment temperature Te is around 0°C and in the period when the outside air temperature Ta is around 10°C. In these periods, the gradient of the cooler compartment temperature Te is almost flat, and there is almost no temperature rise.

[0168] The reason why the rise in the cooler compartment temperature Te becomes gentler near 0° C. is 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 41 is absorbed to melt the frost near 0° C., and the heat from the defrost heater 41 does not contribute to the rise in the cooler compartment temperature Te. In other words, almost all of the heat from the defrost heater 41 is used to melt the frost.

[0169] The reason why the rise in the cooler compartment temperature Te is gentle at around 10°C is that a thermal equilibrium is maintained between the amount of heat (amount of cold air entering) entering the freezer 1, i.e., the cooler compartment 3, from the outside air and the amount of heat generated by the defrost heater 41. If the end threshold temperature T_end is set higher than the outside air temperature Ta, it is necessary to raise the temperature in the cooler compartment 3 above the outside air temperature Ta. If an attempt is made to raise the temperature above the outside air temperature Ta, the amount of heat generated by the defrost heater 41 is lost to the outside air, that is, some of the heat generated by the defrost heater 41 leaks out of the freezer 1, making it difficult for the cooler compartment temperature Te to rise.

[0170] 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 41 raises the temperature inside the cooler compartment 3 to the outside air temperature Ta, the inside of the cooler compartment 3 and the outside air side are in thermal equilibrium. In this state, if an attempt is made to further raise the temperature inside the cooler compartment 3, the thermal equilibrium with the outside air side will be disrupted, requiring even more heat, and the heat generated by energizing the defrost heater 41 will not be used effectively. Therefore, in conventional freezers in which the end threshold temperature T_end is fixed, the energy-saving performance may deteriorate depending on the outside air temperature.

[0171] In contrast, in Fig. 25, the end threshold temperature T_end is changed with reference to the outside air temperature Ta. Therefore, as shown in Fig. 25, during the heater energization period, the temperature rise suddenly becomes gentler and the slope becomes almost flat only when the cooler compartment temperature Te is around 0°C. As described above, the reason why the slope of the temperature rise becomes gentle when the cooler compartment temperature Te is around 0°C is because a very large amount 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 41 is being absorbed by melting the frost, rather than by an increase in the cooler compartment temperature Te, and defrosting is progressing.

[0172] On the other hand, as shown in Fig. 25, there is no region where the gradient suddenly becomes gentler except when the heat equilibrium balance is not achieved and the cooler compartment temperature Te is around 0°C. Therefore, it can be seen that the amount of heat supplied from the defrost heater 41 is less likely to leak to the outside air side compared to the conventional example in Fig. 24.

[0173] FIG. 26 shows the waveforms of the cooler compartment temperature Te in FIGS. 24 and 25 aligned with the timing at which power supply to the defrost heater 41 is started as the starting point. As shown in FIG. 26 , in the conventional example, when the cooler compartment 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 41 is not effectively used. For this reason, the heater power supply period in the conventional example is longer than the heater power supply period in the fourth embodiment. On the other hand, in the fourth embodiment, the end threshold temperature T_end is variable depending on the outside air temperature Ta, so the heat generation amount of the defrost heater 41 is effectively used to defrost the cooler 34. For this reason, the heater power supply period in the fourth embodiment is shorter than the heater power supply period in the conventional example.

[0174] As described above, according to the fourth embodiment, by performing a special defrosting operation before the end of the non-use time period, blockage of the drain pipe 42 can be eliminated, and a pressure balance can be achieved between the inside of the freezer compartment 10 and the space outside the freezer 1, making it easier to open the freezer compartment door 15.

[0175] Furthermore, since the end threshold temperature T_end is variable according to the outside air temperature Ta at which the freezer 1 is actually operating, the power-on time of the defrost heater 41 can be shortened, power consumption can be reduced, and energy-saving performance can be improved.

[0176] Furthermore, by synchronizing the energization of the defrost heater 41 and the drain heater 43, the heat density in the cooler chamber 3 can be increased compared to when only the defrost heater 41 is energized, and it is possible to promote the melting of frost accumulated on the cooler 34. Because the heated warm air is guided to the upper part of the cooler chamber 3, the heat generated by both the defrost heater 41 and the drain heater 43, which are provided below the cooler 34, can be effectively utilized, and the defrosting operation time can be shortened compared to when only the defrost heater 41 is energized, improving energy-saving performance during defrosting operation.

[0177] Although the freezer 1 of the fourth embodiment has been described as being configured to change the end threshold temperature T_end in response to the outdoor air temperature Ta, the freezer 1 of the fourth embodiment is essentially assumed to be used indoors. For example, when the freezer 1 is used at low temperatures, such as an outdoor air temperature of less than 2°C, the end threshold temperature T_end does not need to be changed in response to the outdoor air temperature Ta. This is because, even when the outdoor air temperature is close to 0°C, if the end threshold temperature T_end is changed in response to the outdoor air temperature Ta, the defrosting operation may end at 0°C, the frost melting temperature, resulting in residual frost that does not completely melt. In other words, if the outdoor air temperature Ta is somewhat higher than 0°C and the heat supplied from the defrost heater 41 can be effectively used, the frost can be completely melted, thereby improving energy-saving performance.

[0178] Specifically, the end threshold temperature T_end may be changed in accordance with the outside air temperature Ta only when the outside air temperature Ta is, for example, 2° C. or higher. However, the specific outside air temperature Ta at which the end threshold temperature T_end is changed in accordance with the outside air temperature Ta may be determined in consideration of the configuration of the freezer 1, the user's usage conditions, etc., and the above-mentioned outside air temperature may be set to, for example, 5° C. instead of 2° C.

[0179] Furthermore, if the insulation performance of the freezer 1 itself is low, the thermal balance described in the conventional example of Fig. 24 is likely to occur. This is because if the insulation capacity of the freezer 1 is high, the heat generated by the defrost heater 41 inside the freezer 1 is prevented from leaking into the outside air outside the freezer 1. In other words, the thermal balance is less likely to occur in a freezer 1 that uses a high-performance insulation material such as a vacuum insulation material with high insulation capacity, but is more likely to occur in an inexpensive freezer 1 that does not use a vacuum insulation material. For this reason, in the fourth embodiment, a vacuum insulation material may be used for the insulation member 23 of the freezer 1.

[0180] In the fourth embodiment, the special defrosting operation is performed when the usage frequency rank corresponds to the non-use time period, but this is not limited to this. For example, when the usage frequency rank corresponds to the non-use time period, the defrost heater 41 may not be energized, and only the drain heater 43 may be energized. In this case, too, the closure of the drain pipe 42 is suppressed, and the force required to open and close the door of the freezer 1 can be reduced.

[0181] The freezer 1 may also perform both the special defrosting operation of the fourth embodiment and the suppression operation of the first embodiment. For example, if the current time period is a non-use time period, the suppression operation of the first embodiment may be performed, and if the remaining time tz of the non-use time period becomes equal to or less than the end threshold time t_end, the freezer 1 may perform the special defrosting operation.

[0182] The above is a description of the embodiments, but the present disclosure is not limited to the following embodiments and can be modified in various ways without departing from the spirit of the present disclosure. Furthermore, the present disclosure includes all possible combinations of the configurations shown in the following embodiments and their modifications. For example, the configuration and control of the freezer 1 in the above embodiment can also be applied to a storage facility other than the freezer 1 that cools stored items to a single temperature range. In this case, thresholds for ranking and distinguishing the items are appropriately set according to the temperature range of the storage compartment.

[0183] In the above embodiment, the stored items stored in the freezer compartment 10 are described as food, but this is not limiting. For example, the stored items may be items 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.

[0184] Furthermore, in the above embodiment, the freezer compartment door 15 is configured to include two doors, an upper door 15a and a lower door 15b, but this is not limited to this. Fig. 27 is a front view of a freezer 1A according to Modification 1. Fig. 28 is a cross-sectional schematic view of the freezer 1A according to Modification 1. Fig. 28 is a view of the freezer 1A shown in Fig. 27 cut along line A-A and viewed from the direction of the arrows. As shown in Figs. 27 and 28, the freezer compartment door 15 may be a single door.

[0185] In this case, the opening / closing sensor 17 is provided at the front of the top or bottom surface of the main body 2. Note that, when the main body 2 is the same size, if the door type of the freezer 1 is a two-door type as in the above embodiment rather than a one-door type as in this modified example, leakage of cold air during a single opening / closing can be suppressed.

[0186] Furthermore, in the case where freezer compartment 10 is opened and closed by two doors as in the embodiment, opening and closing of upper door 15a and lower door 15b may be detected separately, and an adjustment coefficient α1 may be set separately for when upper door 15a is opened and an adjustment coefficient α2 may be set separately for when lower door 15b is opened. Then, the product of the average number of times upper door 15a is opened and the average open time thereof, and the product of the average number of times lower door 15b is opened and the average open time thereof, and the adjustment coefficient α2 thereof may be averaged to obtain discrimination parameter X, which may be used to determine the usage frequency rank.

[0187] REFERENCE SIGNS LIST 1, 1A freezer, 2 main body, 3 cooler compartment, 6 control device, 10 freezer compartment, 11 upper freezer compartment, 12 lower freezer compartment, 13 shelf, 14 storage container, 15 freezer compartment door, 15a upper door, 15b lower door, 16 door partition, 17 opening / closing sensor, 18 operation display unit, 18a operation unit, 18b display unit, 19 outside air temperature sensor, 21 outer box, 22 inner box, 23 heat insulating member, 30 machine compartment, 31 compressor, 32 condenser, 33 pressure reducing device, 34 cooler, 34a inlet, 34b outlet, 35 blower, 36 cooler compartment temperature sensor, 41 defrost heater, 42 drain pipe, 43 drain heater, 44 drain pan, 51 Upper air duct, 51a, 51b, 51c: air outlet, 52 Lower air duct, 52a, 52b, 52c: air outlet, 53: internal temperature sensor, 54: return air duct, 54a: inlet, 61: memory unit, 62: cooling control unit, 63: heater control unit, 64: adjustment coefficient calculation unit, 65: rank determination unit, 66: judgment unit, 341: fins, 342: heat transfer tubes, 343: connecting tubes, 510, 520: wall surface, 600: processing circuit, 601: processor, 602: memory, 603: bus.

Claims

1. A refrigerator for cooling stored items within a single temperature range, comprising: a main body having a storage compartment and a cooler compartment; a door provided on the front surface of the storage compartment; a cooler disposed in the cooler compartment for generating cold air through heat exchange with a refrigerant; a blower for sending the cold air to the storage compartment; a compressor for sending the refrigerant to the cooler; an in - storage temperature sensor for measuring the in - storage temperature, which is the temperature of the storage compartment; a cooler - compartment temperature sensor for measuring the cooler - compartment temperature, which is the temperature of the cooler compartment; an open - close sensor for detecting the opening and closing of the door; a control device for controlling the compressor and the blower, wherein the control device: determines a usage frequency rank for each time period based on the number of times the door is opened and closed; when the current time period is an unused time period with the lowest usage frequency rank, determines whether the temperature difference between the in - storage temperature and the cooler - compartment temperature is equal to or greater than a threshold temperature; and when the temperature difference is equal to or greater than the threshold temperature, performs a suppression operation of operating the blower and stopping the compressor.

2. The refrigerator according to claim 1, wherein the usage frequency rank is obtained by multiplying the number of times the door is opened and closed for each time period by the door open time.

3. The refrigerator according to claim 1, wherein the usage frequency rank is obtained by multiplying an adjustment coefficient indicating the ratio of stored items being put into the storage compartment when the door is opened and closed, the number of times the door is opened and closed for each time period, and the door open time.

4. The control device: obtains the temperature rise value of the in - storage temperature when the door is opened and closed; and obtains the return time required for the in - storage temperature to return to the temperature before the door was opened after the door is opened and closed. When the temperature rise value is equal to or greater than a threshold and the return time is equal to or greater than a threshold time, determines that stored items have been put into the storage compartment when the door is opened and closed. The refrigerator according to claim 3, wherein the adjustment coefficient is calculated by dividing the number of times the door is opened and closed determined to have stored items put into the storage compartment during a preset calculation period by the total number of times the door is opened and closed during the calculation period.

5. The control device: obtains the temperature rise value of the in - storage temperature and the temperature rise value of the cooler - compartment temperature when the door is opened and closed; and obtains the return time required for the in - storage temperature to return to the temperature before the door was opened and the return time required for the cooler - compartment temperature to return to the temperature before the door was opened when the door is opened and closed. When both the temperature rise values of the internal temperature and the cooler chamber temperature are equal to or higher than the threshold value, and both the return times of the internal temperature and the cooler chamber temperature are equal to or longer than the threshold time, it is determined that the stored item has been put into the storage chamber when the door is opened or closed. The storage cabinet according to claim 3, wherein the adjustment coefficient is calculated by dividing the number of times the door is opened and closed when it is determined that the stored item has been put in during a preset calculation period by the total number of times the door is opened and closed during the calculation period.

6. In the suppression operation, the control device starts the operation of the blower by setting the rotation speed of the blower to the minimum rotation speed, repeatedly calculates the temperature gradient of the internal temperature at preset time intervals, The storage cabinet according to any one of claims 1 to 5, wherein when the latest temperature gradient becomes less than the previous temperature gradient, the rotation speed of the blower is increased.

7. The storage cabinet according to any one of claims 1 to 5, wherein the control device varies the set temperature of the internal temperature based on the usage frequency rank.

8. It is provided with an outside air temperature sensor that measures the outside air temperature, which is the temperature of the space outside the storage chamber partitioned by the door, The control device determines the outside air rank for each time zone based on the outside air temperature, The storage cabinet according to any one of claims 1 to 5, wherein the rotation speed of the compressor, or the rotation speeds of the compressor and the blower are varied based on the usage frequency rank and the outside air rank.

9. A defrost heater that melts the frost adhering to the cooler during the defrost operation, A drain pipe that discharges the melted water of the frost, The storage cabinet according to any one of claims 1 to 5, further comprising a drain heater that thaws the freeze of the drain pipe.

10. The storage cabinet according to claim 9, wherein the control device operates the defrost heater and the drain heater synchronously.

11. The storage cabinet according to claim 9, wherein the control device performs the defrost operation when the current time zone is the non - use time zone.

12. The control device compares the cooler chamber temperature with the end threshold temperature to determine whether to end the defrost operation, The storage cabinet according to claim 9, wherein when the outside air temperature is less than the end threshold temperature, the end threshold temperature is changed to the outside air temperature.