refrigerator

Abstract

To provide a refrigerator capable of suppressing the drying of frozen products to maintain the quality of the frozen products.SOLUTION: A refrigerator comprises: a refrigeration cycle including a compressor and a cooler; a cooler chamber that houses the cooler; a refrigeration chamber that houses a first container and is open at the front; a refrigeration chamber door that can freely open and close the opening of the refrigeration chamber; and a refrigeration fan that blows air cooled by the cooler into the refrigeration chamber. In a stable state, a time-average temperature of a bottom surface of the first container is lower than a time-average temperature of air in a storage space of the first container.SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] The present invention relates to a refrigerator.

Background Art

[0002] Refrigerators are known that can switch the flow of cold air blown into the freezer compartment. For example, Patent Document 1 discloses that when the blower fan rotates forward, cold air is blown out from one opening and sucked in from the other opening, and when the blower fan rotates backward, cold air is blown out from the other opening and sucked in from one opening.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technology disclosed in Patent Document 1, the flow of cold air is switched with the intention of stirring the air in the freezer compartment to make the whole at an even temperature, and only mentions that the switching timing is periodic or aperiodic. Also, there are states where the blower fan is stopped, such as during refrigeration operation or defrosting operation, but there is no mention of in what order to switch the rotation direction of the blower fan from that state.

Means for Solving the Problems

[0005] To solve the aforementioned problems, for example, the configuration described in the claims is adopted. The refrigerator of the present invention includes a plurality of means for solving the aforementioned problems, but to give one example, it comprises a refrigeration cycle including a compressor and a cooler, a cooler chamber housing the cooler, a freezer chamber housing a first container and having an opening at the front, a freezer chamber door that can open and close the opening of the freezer chamber, and a refrigeration fan that blows air cooled by the cooler into the freezer chamber, wherein in a stable state, the time-averaged temperature of the bottom surface of the first container is lower than the time-averaged temperature of the air in the storage space of the first container. [Brief explanation of the drawing]

[0006] [Figure 1] Front view of a refrigerator according to this embodiment [Figure 2] Longitudinal cross-sectional view of a refrigerator according to this embodiment [Figure 3] Front view showing the interior configuration of the refrigerator according to this embodiment. [Figure 4] Configuration diagram of the refrigeration cycle of the refrigerator according to this embodiment. [Figure 5] Perspective view showing the configuration of the refrigerator door and container according to the embodiment. [Figure 6] A diagram showing the airflow during normal refrigeration operation. [Figure 7] Diagram showing airflow during container cooling and refrigeration operation. [Figure 8] Graph showing temperature changes inside the freezer in Example 1 [Figure 9] Flowchart showing the control immediately after the lower freezer compartment door is closed in Example 1. [Figure 10] Flowchart showing control when the freezer compartment is in a stable state in Example 1 [Figure 11] Graph showing temperature changes (stable state) between food and ambient air in the comparative example. [Figure 12] Graph showing temperature changes (stable state) between food and ambient air in Example 1. [Figure 13] Graph showing the temperature change inside the freezer compartment immediately after the lower freezer compartment door is closed in Example 2. [Figure 14]Flowchart showing the control immediately after the lower freezer door in Example 2 is closed [Figure 15] Graph showing the temperature changes of food and the surrounding air (immediately after the door is closed) in the comparative example [Figure 16] Graph showing the temperature changes of food and the surrounding air (immediately after the door is closed) in Example 2 [Figure 17] Graph showing the temperature change inside the freezer immediately after the lower freezer door in a modified example of Example 2 is closed [Figure 18A] Schematic diagram of the first air duct for switching the circulation direction using a damper [Figure 18B] Schematic diagram of the second air duct for switching the circulation direction using a damper [Figure 19] Diagram showing the structure of the container in a modified example of Example 1

Modes for Carrying Out the Invention

[0007] Hereinafter, embodiments of the present invention will be described.

[0008] In the description according to the embodiment, when considering the establishment of a condition in which a plurality of conditions are connected by "or", any single establishment of the plurality of conditions or any meaning in the union of the plurality of conditions is included. For example, the description "When condition A or condition B is established, process C is executed" shall include any meaning of "When condition A is established, process C is executed", "When condition B is established, process C is executed", and "When any one or both of condition A and condition B are established, process C is executed".

[0009] In this embodiment, in particular, it is considered to store frozen food packaged in a package. If the food remains at a higher temperature than the air inside the package for a long time, moisture is likely to sublime from the surface of the food, and the sublimated moisture adheres as frost to the inside of the package. If this is repeated, the food will dry out.

[0010] <Basic Configuration of the Refrigerator> First, the basic configuration of the refrigerator according to this embodiment will be described with reference to FIGS. 1 to 4. FIG. 1 is a front view of the refrigerator according to this embodiment, FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1, FIG. 3 is a cross-sectional view taken along line B-B of FIG. 2, and FIG. 4 is a schematic diagram showing the configuration of the refrigeration cycle of the refrigerator according to this embodiment.

[0011] As shown in FIG. 1, the refrigerator body 10 of the refrigerator 1 is open at the front, and a storage chamber is formed in the order of the refrigerating chamber 2 from above, the ice-making chamber 3 arranged side by side left and right, the upper freezing chamber 4, the lower freezing chamber 5, and the vegetable chamber 6. Hereinafter, the ice-making chamber 3, the upper freezing chamber 4, and the lower freezing chamber 5 may be collectively referred to as the freezing chamber 7.

[0012] The opening in front of the refrigerating chamber 2 is opened and closed by the rotary refrigerating chamber doors 210a and 210b divided left and right, and the openings in front of the ice-making chamber 3, the upper freezing chamber 4, the lower freezing chamber 5, and the vegetable chamber 6 are opened and closed by the drawer-type ice-making chamber door 310, the upper freezing chamber door 410, the lower freezing chamber door 510, and the vegetable chamber door 610, respectively.

[0013] As shown in FIG. 2, the refrigerator body 10 formed by filling a foamed heat insulating material (for example, foamed urethane) between the outer box 10a and the inner box 10b separates the outside and the inside of the refrigerator 1. In addition to the foamed heat insulating material, a vacuum heat insulating material 25 is mounted on the ceiling surface, the back surface, the bottom surface, both side surfaces of the refrigerator body 10, and the lower freezing chamber door 51 . The refrigerating chamber 2, the upper freezing chamber 4, and the ice-making chamber 3 are separated by a heat insulating partition wall 28, and the lower freezing chamber 5 and the vegetable chamber 6 are separated by a heat insulating partition wall 29.

[0014] Furthermore, the front sides of each storage compartment—the ice-making compartment 3, the upper freezer compartment 4, and the lower freezer compartment 5—are equipped with an insulating partition wall 30 to prevent air circulation between the inside and outside of the compartment through the gap between the ice-making compartment door 310, the lower surface of the upper freezer compartment door 410, and the upper surface of the lower freezer compartment door 510, and an insulating partition wall 31 (see Figure 1) to prevent air circulation between the inside and outside of the compartment through the gap between the right side of the ice-making compartment door 310 and the left side of the upper freezer compartment door 410. Additionally, an insulating partition wall 36 is rotatably mounted on the right end of the refrigerator compartment door 210a on the inside of the compartment to prevent air circulation between the inside and outside of the compartment through the gap between doors 210a and 210b when the refrigerator compartment doors 210a and 210b are closed (see Figure 1).

[0015] The interior side of the doors 210a and 210b of the refrigerator compartment 2 is provided with multiple door pockets 33a, 33b, and 33c that open upwards, and multiple shelves 34a, 34b, 34c, and 34d, dividing it into multiple storage spaces. The freezer compartment 7 and the vegetable compartment 6 are equipped with an ice-making container 301, an upper freezer container 401, a middle lower freezer container 502, a lower lower freezer container 503, an upper vegetable compartment container 601, and a lower vegetable compartment container 602, which are pulled out together with the doors 310, 410, 510, and 610, respectively. The upper lower freezer container 501, which is installed above the lower freezer compartment 5, is supported by a guide rail (not shown) molded into the inner box 10b, and remains inside the compartment when the lower freezer door 510 is pulled out, instead of being pulled out together with the lower freezer door 510.

[0016] Refrigerator 1 is equipped with a refrigerating evaporator compartment 8a (refrigerating cooler compartment) located approximately at the rear of the refrigerator compartment 2, and a refrigerating evaporator 14a (refrigerating cooler) is housed inside the refrigerating evaporator compartment 8a. A refrigerating fan 9a is provided above the refrigerating evaporator 14a. Furthermore, a refrigerator compartment air passage 11 is provided approximately at the center in the width direction of the rear of the refrigerator compartment 2, and refrigerator compartment outlets 11a are provided on the left and right sides of the upper and middle parts of the refrigerator compartment air passage 11. Cooling air blown out from the refrigerator compartment outlets 11a flows forward above shelf 34a and between shelf 34a and 34b, as shown by arrows in Figure 2, then downward through the gap between shelf 34a, 34b, 34c and door pocket 33a, 33b, 33c, and reaches the rear area of ​​the low-temperature compartment 35 through an opening 92 (see Figure 3) provided at the left rear of the space between shelf 34c and shelf 34d. The airflow that reaches the rear region of the low-temperature chamber 35 returns to the refrigerated evaporator chamber 8a through the refrigerated chamber return ports 15a, 15b, and 15c (see Figure 3) located on the lower front, lower left side, and lower right front of the refrigerated evaporator chamber 8a. In addition, some of the air that flows through the space between shelves 34c and 34d returns to the refrigerated evaporator chamber 8a through the refrigerated chamber return port 15d (see Figure 3) located on the right rear of the space between shelves 34c and 34d.

[0017] The freezer compartment 7 is equipped with a freezer evaporator compartment 8b (freezer cooler compartment) near its rear, and a freezer evaporator 14b (freezer cooler) is housed inside the freezer evaporator compartment 8b. A freezer fan 9b is provided above the freezer evaporator 14b. The freezer compartment 7 is also equipped with a freezer air passage 12 at its rear, and the freezer air passage 12 in front of the freezer fan 9b (second fan) (downstream during normal operation) is equipped with multiple freezer outlets (a first freezer outlet 12a that mainly discharges to the upper freezer compartment 4 or ice-making compartment 3, and a second freezer outlet 12b that mainly discharges to the lower freezer compartment 5). The lower front of the freezer evaporator compartment 8b is equipped with a freezer return port 17 (see Figures 2 and 3) to which the air sent to the freezer compartment 7 returns. The first freezer compartment outlet 12a and the second freezer compartment outlet 12b are located above the ice-making container 301, the upper freezer compartment container 401, the upper container 501 of the lower freezer compartment, the middle container 502 of the lower freezer compartment, and the lower container 503 of the lower freezer compartment, respectively, and on the side of the freezer compartment airflow passage 12, allowing cold air to flow into each container. The first freezer compartment outlet 12a and the second freezer compartment outlet 12b are also arranged almost uniformly in the left-right direction. This allows the stored food to be cooled quickly. The freezer compartment return port 17 located at the bottom of the freezer compartment 7 is formed to be approximately the same width as the freezer evaporator 14, so that the cold air returning from the freezer compartment flows efficiently into the freezer evaporator 14. The vegetable compartment airflow passage 13, which serves as an air passage to the vegetable compartment 6, branches off from the lower right of the freezer compartment airflow passage 12 and passes through the insulated partition wall 29. The vegetable compartment outlet 13a, which is the outlet of the vegetable compartment air passage 13, is provided so as to be approximately the same height as the lower surface of the insulating partition wall 29 on the upper right rear of the vegetable compartment 6, and opens downwards. The vegetable compartment air passage 13 is equipped with a vegetable compartment damper 19, which is a means for controlling the cooling of the vegetable compartment 6 (see Figure 3). A vegetable compartment return port 18a is provided at the lower front left of the insulating partition wall 29 between the vegetable compartment 6 and the freezer compartment 7, and a flow path is formed that leads to the vegetable compartment return outlet 18b provided at the lower front of the freezer evaporator compartment 8b via the vegetable compartment return air passage 18 that passes through the insulating partition wall 29.

[0018] In this embodiment of the refrigerator, the refrigeration fan 9a is a centrifugal fan (rear-facing fan), and the freezing fan 9b is an axial flow fan (propeller fan). A centrifugal fan has the characteristic of drawing in air axially, reversing it by 90 degrees, and blowing it radially. On the other hand, an axial flow fan has the characteristic of drawing in air axially and blowing it axially. For this reason, centrifugal fans offer superior implementability in air passages where the flow drawn in axially is reversed by 90 degrees, while axial flow fans offer superior implementability in air passages where the flow drawn in axially is blown out axially. The refrigeration fan 9a is installed to draw in air from the front, reversing it by 90 degrees, and blowing it out into the upper refrigerator compartment air passage 11, so a rear-facing centrifugal fan is used. The freezing fan 9b is installed to draw in air from the rear and blow it out into the front freezer compartment air passage 12, so an axial flow fan, a propeller fan, is used, resulting in a refrigerator with high space efficiency.

[0019] As shown in Figures 2 and 3, the refrigerator compartment 2, freezer compartment 7, and vegetable compartment 6 are equipped with a refrigerator compartment temperature sensor 41, a freezer compartment temperature sensor 42, and a vegetable compartment temperature sensor 43 on the rear side of the interior of each compartment, detecting the temperature of the refrigerator compartment 2, freezer compartment 7, and vegetable compartment 6, respectively. In addition, a refrigerator evaporator temperature sensor 40a is installed above the refrigerator evaporator 14a, and a freezer evaporator temperature sensor 40b is installed above the freezer evaporator 14b, detecting the temperature of the refrigerator evaporator 14a and freezer evaporator 14b, respectively. Furthermore, an outside temperature and humidity sensor 37 is installed on the ceiling of the refrigerator 1 to detect the temperature and humidity of the outside air (air outside the compartment). Doors 210a, 210b, 310, 410, 510, and 610 are each equipped with a magnet (not shown) for detecting the door open or closed state, and the front surfaces of the insulating partition walls 28, 29, and 30 facing the magnets of each door are each equipped with door sensors (not shown), which are magnetic sensors that determine the door open or closed state by detecting a magnetic field.

[0020] Furthermore, a defrost heater 21 for heating the refrigeration evaporator 14b is provided at the bottom of the refrigeration evaporator chamber 8b. The defrost water (melted water) generated during defrosting of the refrigeration evaporator 14b flows down into a gutter 23b located at the bottom of the refrigeration evaporator chamber 8b, and through the drain outlet 22b and the refrigeration drain pipe 27b to the machine room 39 located at the rear (back side) of the refrigerator 1, where it is discharged into the evaporation tray 32 above the compressor 24 installed in the machine room 39.

[0021] Furthermore, the defrost water generated during defrosting of the refrigerated evaporator 14a flows down into a gutter 23a located at the bottom of the refrigerated evaporator chamber 8a, and is discharged to the evaporation tray 32 located at the top of the compressor 24 via the drain outlet 22a and the refrigerated drain pipe 27a.

[0022] The machine room 39 houses the aforementioned compressor 24 and evaporator tray 32, as well as an external radiator 50a, which is a fin-tube type heat exchanger, and an external fan 26. The external fan 26 drives air to flow to the compressor 24, external radiator 50a, and evaporator tray 32, promoting heat dissipation from the compressor 24 and external radiator 50a, thereby improving energy efficiency. Additionally, by providing ventilation to the evaporator tray 32, it promotes the evaporation of defrost water accumulated in the evaporator tray 32, suppressing overflow and improving reliability.

[0023] As shown in Figure 3, the gutter 23a is equipped with a gutter heater 101 to melt the defrost water that has frozen in the gutter 23a. The refrigerated drain pipe 27a is also equipped with an upper drain pipe heater 102 and a lower drain pipe heater 103. Note that the gutter heater 101, the upper drain pipe heater 102, and the lower drain pipe heater 103 are all heaters with a lower capacity than the defrost heater 21.

[0024] When the refrigeration fan 9a is driven, the return air from the refrigerator compartment 2 is directed downwards toward the gutter 23a via the refrigerator compartment return port 15b located in the upper right of the refrigerator evaporator compartment 8a, thereby heating the gutter 23a and raising its temperature. This reduces the amount of heat required by the gutter heater 101, which melts the frozen defrost water in the gutter 23a, thereby improving energy efficiency.

[0025] Figure 4 shows the refrigeration cycle (refrigerant circuit) of the refrigerator according to this embodiment. The refrigerator 1 of this embodiment includes a compressor 24, an external heat exchanger 50a which is a fin tube type heat exchanger that dissipates heat from the refrigerant, an external heat exchanger 50b which is a heat dissipation pipe provided on the inner side of the outer casing 10a (see Figures 2 and 3), a condensation suppression pipe 50c which suppresses condensation on the front edges of the insulated partition walls 28, 29, and 30 (the external heat exchangers 50a, external heat exchangers 50b, and condensation suppression pipe 50c are referred to as heat dissipation means), a three-way valve 52 which is a refrigerant flow control means, a refrigeration capillary tube 53a and a freezing capillary tube 53b which are pressure reducing means for reducing the pressure of the refrigerant, a refrigeration evaporator 14a which exchanges heat between the refrigerant and the air inside the refrigerator and absorbs heat from inside the refrigerator. Furthermore, upstream of the three-way valve 52 is a dryer 51 for removing moisture in the refrigeration cycle, and downstream of the refrigeration evaporator 14a and downstream of the refrigeration evaporator 14b are gas-liquid separators 54a and 54b, respectively, to prevent liquid refrigerant from flowing into the compressor 24. Further downstream of the gas-liquid separator 54b is a check valve 56. These components are connected by refrigerant piping to form the refrigeration cycle.

[0026] The three-way valve 52 is a refrigerant flow control valve equipped with an outlet 52a and an outlet 52b, and has three states: State 1 (refrigeration mode) in which the refrigerant flows to the refrigeration capillary tube 53a side with outlet 52a open and outlet 52b closed; State 2 (freezing mode) in which the refrigerant flows to the freezing capillary tube 53b side with outlet 52a closed and outlet 52b open; and State 3 (fully closed mode) in which both outlets 52a and 52b are closed.

[0027] When the three-way valve 52 is controlled to state 1 (refrigeration mode), the refrigerant discharged from the compressor 24 flows through the external heat exchanger 50a, external heat exchanger 50b, and condensation suppression piping 50c to dissipate heat, and then reaches the three-way valve 52 via the dryer 51. Since the three-way valve 52 is in state 1 (outlet 52a is open, outlet 52b is closed), the refrigerant then flows through the refrigeration capillary tube 53a, is depressurized, and reaches the refrigeration evaporator 14a, where it exchanges heat with the return air in the refrigerator compartment 2. After leaving the refrigeration evaporator 14a, the refrigerant passes through the gas-liquid separator 54a, flows through the contact point 57a with the refrigeration capillary tube 53a, exchanges heat with the refrigerant flowing inside the refrigeration capillary tube 53a, and then returns to the compressor 24.

[0028] When the three-way valve 52 is controlled to state 2 (freezing mode), the refrigerant discharged from the compressor 24 flows through the external heat exchanger 50a, external heat exchanger 50b, and condensation suppression piping 50c to dissipate heat, and then reaches the three-way valve 52 via the dryer 51. Since the three-way valve 52 is in state 2 (outlet 52a closed, outlet 52b open), the refrigerant then flows through the refrigeration capillary tube 53b, is depressurized and cooled, and then exchanges heat with the return air from the freezer compartment 7 and the return air from the vegetable compartment 6 (when the vegetable compartment damper 19 is open) in the refrigeration evaporator 14b. The refrigerant that leaves the refrigeration evaporator 14b passes through the gas-liquid separator 54b, flows through the contact part 57b with the refrigeration capillary tube 53b, exchanges heat with the refrigerant flowing inside the refrigeration capillary tube 53b, and then returns to the compressor 24.

[0029] When the three-way valve 52 is controlled to state 3 (fully closed mode), driving the compressor 24 will result in a state where refrigerant is not supplied from the refrigeration capillary tube 53a and the freezing capillary tube 53b, allowing the refrigerant in the refrigeration evaporator 14a or the freezing evaporator 14b to be recovered to the heat dissipation means.

[0030] The refrigerator of this embodiment operates in a "refrigeration mode" where the three-way valve 52 is controlled to state 1 (refrigeration mode), the compressor 24 is driven, the refrigeration fan 9a is driven, and the freezing fan 9b is stopped to cool the refrigerator compartment 2; and in a "freezing mode" where the three-way valve 52 is controlled to state 2 (freezing mode), the compressor 24 is driven, the vegetable compartment damper 19 is open, the refrigeration fan 9a is driven or stopped, and the freezing fan 9b is driven to cool the freezer compartment 7 and the vegetable compartment 6. "Freezing Vegetable Operation": The three-way valve 52 is controlled to state 2 (freezing mode), the compressor 24 is driven, the vegetable compartment damper 19 is closed, the refrigeration fan 9a is driven or stopped, and the freezing fan 9b is driven to cool the freezer compartment 7. "Refrigeration Operation": The three-way valve 52 is controlled to state 3 (fully closed mode), the compressor 24 is driven, and the refrigerant in the refrigeration evaporator 14a or the freezing evaporator 14b is recovered to the heat dissipation means side. "Operation stop" is performed by setting the three-way valve 52 to state 3 (fully closed mode), stopping the compressor 24, stopping the refrigeration fan 9a, and stopping the freezing fan 9b. Alternatively, the three-way valve 52 can be controlled to state 2 (freezing mode) and the compressor 24 can be controlled to state 3 (fully closed mode) and the compressor 24 can be stopped, so that no refrigerant flows to the refrigeration evaporator 14a, and the refrigeration fan 9a can be driven to allow growth on the surface of the refrigeration evaporator 14a. The refrigerator 1 cools each storage compartment by appropriately performing the following operations: "refrigerator evaporator defrosting operation," which cools the refrigerator compartment 2 with frost and the stored cold heat of the evaporator itself while defrosting the refrigerator evaporator 14a; and "refrigerator evaporator defrosting operation," which defrosts the freezer evaporator 14b by setting the three-way valve 52 to state 3 (fully closed mode), stopping the compressor 24, driving or stopping the refrigerator fan 9a, stopping the freezer fan 9b, and energizing the defrost heater 21.

[0031] Although not shown in the diagram, the machine room 39 of refrigerator 1 houses a control board (control unit) equipped with a CPU, memory such as ROM and RAM, interface circuits, etc. The control board is connected to the refrigerator compartment temperature sensor 41, the freezer compartment temperature sensor 42, the vegetable compartment temperature sensor 43, the refrigerator evaporator temperature sensor 40a, the freezer evaporator temperature sensor 40b, the door sensor, etc. Based on these output values, temperature settings, and programs pre-recorded in the ROM, the aforementioned CPU controls the ON / OFF and rotation speed of the compressor 24, the refrigerator fan 9a, the freezer fan 9b, the defrost heater 21, the gutter heater 101, the drain pipe upper heater 102, the drain pipe lower heater 103, and the three-way valve 52, which will be described later.

[0032] <Configuration of containers stored in the lower freezer compartment> As shown in Figure 5, the lower freezer compartment container 503 is supported by a pair of left and right iron frames 520 fixed to the inner surface of the lower freezer compartment door 510. The middle freezer compartment container 502 is placed on top of the lower freezer compartment container 503, supported by a pair of left and right legs 502b and 502c at the front and rear, respectively. Here, the front leg 502b of the middle freezer compartment container 502 is locked into a recess 503b formed on the upper surface of the outer wall of the lower freezer compartment container 503. As a result, when the lower freezer compartment door 510 is pulled out, the middle freezer compartment container 502 is pulled out together with the lower freezer compartment container 503, which is supported by the frames 520. The frames 520 are equipped with connecting members 522 at the rear of the lower freezer compartment container 503 to connect the left and right frames 520 in order to prevent deformation. Furthermore, a bearing 521 is provided at the lower rear edge of the frame 520 to ensure smooth pulling operation. The ice-making compartment container 301 and the upper freezer compartment container 401 are supported by a frame fixed to the ice-making compartment door 310 and the upper freezer compartment door 410, similar to the lower freezer compartment container 503, and are designed to be pulled out together with the ice-making compartment door 310 and the upper freezer compartment door 410.

[0033] (Normal) Freezing Operation Next, the airflow within the freezer chamber during refrigeration operation will be explained. Figure 6 is an enlarged cross-sectional view of the vicinity of the freezer chamber in Figure 2, showing the airflow during normal refrigeration operation. The freezer chamber has a first freezer chamber outlet 12a and a second freezer chamber outlet 12b, which are first openings located above the opening of the lower container 503 of the lower freezer chamber (the upper side edge of the lower container 503 of the lower freezer chamber), and a second freezer chamber return port 17, which is located below the opening of the lower container 503 of the lower freezer chamber. A first air passage connecting the first opening and the refrigeration evaporator 14b, and a second air passage connecting the second opening and the refrigeration evaporator 14b are formed within the refrigeration evaporator chamber 8b. The second opening communicates with the lower side of the refrigeration evaporator 14b.

[0034] During refrigeration operation, the compressor 24 and the refrigeration fan 9b are driven, as described above. Then, the cooled air that moves from the bottom to the top of the refrigeration evaporator 14b is supplied to the freezer chamber through the first air passage and the first opening (see the thin solid arrow in Figure 6), flows from top to bottom as shown by the thick arrow in Figure 6, and then returns to the refrigeration evaporator 14b through the second opening and the second air passage (see the thin dotted arrow in Figure 6). In this embodiment, the reduction of frost formation on frozen food stored in the lower container 503 of the lower freezer chamber is described, but frost formation can be similarly reduced for the other containers 401, 501, and 502 as long as the vertical relationship with the container opening is maintained. [Examples]

[0035] Next, the refrigeration operation in Example 1 will be described. In Example 1, in addition to the refrigeration operation described above (normal refrigeration operation), a container cooling refrigeration operation is performed.

[0036] <Container cooling and refrigeration operation> Figure 7 is an enlarged cross-sectional view of the vicinity of the freezer chamber in Figure 2, showing the airflow during container cooling refrigeration operation. During container cooling refrigeration operation, the compressor 24 and the refrigeration fan 9b are also in operation, but the rotation direction of the refrigeration fan 9b is reversed compared to normal refrigeration operation. Therefore, during container cooling refrigeration operation, the cooled air that moves from the top to the bottom of the refrigeration evaporator 14b passes through the second air passage and is supplied into the freezer chamber from the second opening (see the thin solid arrow in Figure 7), flows from bottom to top as shown by the thick arrow in Figure 7, and then returns to the top of the refrigeration evaporator 14b through the first opening and the first air passage (see the thin dotted arrow in Figure 7). During container cooling refrigeration operation, the second air passage becomes high pressure due to the reverse rotation of the refrigeration fan 9b, making it easier for cold air to be discharged from openings other than the second opening which is connected to the second air passage. In this embodiment, since the second air passage is provided with a vegetable compartment return port 18b and a vegetable compartment discharge port 13a as openings other than the second opening, unintended inflow into the vegetable compartment 6 may become a problem. Therefore, backflow may be suppressed by closing the vegetable compartment damper 19 during container cooling and freezing operation. Note that this unintended inflow can also be a problem even if only one of the discharge and return ports for storage compartments other than the freezer compartment is provided in the second air passage. By providing a damper at the opening communicating with the second air passage and closing it during container cooling and freezing operation, inflow into the storage compartment communicating with this opening can be effectively suppressed.

[0037] Here, we will focus on the lower container 503 of the lower freezer compartment and explain the cooling effect of the container. First, the second freezer compartment discharge port 12b, which is the lowest of the first openings, is located above the upper end of the rear wall of the lower container 503 of the lower freezer compartment. Therefore, even if cold air is discharged from the second freezer compartment discharge port 12b during normal freezing operation, the effect of cooling the lower container 503 of the lower freezer compartment itself is low. On the other hand, the second opening, the freezer compartment return port 17, blows cold air to the underside of the bottom surface of the lower container 503 of the lower freezer compartment when discharging cold air. There can be one or more second openings, but all are located below the upper end of the rear wall of the lower container 503 of the lower freezer compartment. It is preferable that at least a part of the freezer compartment return port 17 is located below the bottom surface of the lower container 503 of the lower freezer compartment. Therefore, when cold air is discharged from the freezer return port 17 during container cooling and freezing operation, the bottom surface of the lower container 503 in the lower freezer compartment can be efficiently cooled, and the food above that bottom surface can also be efficiently cooled.

[0038] Thus, the container cooling refrigeration operation (second cooling operation) primarily targets the bottom surface of the container, and can efficiently cool the bottom surface of the container. However, compared to the normal refrigeration operation (first cooling operation), which primarily targets the air in the storage space, the container cooling refrigeration operation takes longer to cool the entire food in the freezer and is inferior in terms of power consumption. For this reason, in Example 1, the container cooling refrigeration operation and the normal refrigeration operation are combined, and the time of the normal refrigeration operation is made longer than the time of the container cooling refrigeration operation, either in a stable state or in a state other than a stable state, as described later.

[0039] The refrigeration fan 9b rotates in the forward direction during normal refrigeration operation and is designed to efficiently blow air with minimal airflow loss during forward rotation. On the other hand, during container cooling refrigeration operation, the fan rotates in the reverse direction. In reverse rotation, the refrigeration evaporator 14b is located downstream of the refrigeration fan 9b, causing the swirling air to collide with the fins (not shown) of the refrigeration evaporator 14b, resulting in low airflow efficiency due to airflow loss. Therefore, it is desirable to install a wind deflector (flow straightener) between the refrigeration fan 9b and the refrigeration evaporator 14b to guide the air discharged from the refrigeration fan 9b to the fins of the refrigeration evaporator 14b and recover the swirling component. Also, since the flow rate tends to decrease when the refrigeration fan 9b rotates in the reverse direction compared to when it rotates in the forward direction, the rotation speed may be increased compared to when it rotates in the forward direction.

[0040] Furthermore, the aforementioned container cooling refrigeration operation reversed the airflow circulating in the freezer compartment by reversing the rotation direction of the refrigeration fan 9b compared to normal refrigeration operation. However, other methods may be used to efficiently cool the container. For example, by adding air passages other than the aforementioned first and second air passages, it may be possible to switch between discharge and suction (return) from the first and second openings. Figures 18A and 18B are schematic diagrams of air passages in a refrigerator that switch the circulation direction of cold air in the freezer compartment through the control of dampers provided in the air passages, instead of switching the rotation direction of the refrigeration fan 9b. Figure 18A is a schematic diagram of the first air passage, and Figure 18B is a schematic diagram of the second air passage.

[0041] In the freezer chamber shown in Figure 18A, the discharge side of the refrigeration fan 9b is connected to the first opening 12a and the second opening 17b. A first discharge damper 70a, which can be opened and closed, is positioned between the discharge side of the refrigeration fan 9b and the first opening 12a, and a second discharge damper 70b, which can be opened and closed, is positioned between the discharge side of the refrigeration fan 9b and the second opening 17b. The return side of the refrigeration fan 9b is also connected to the first opening 12b and the second opening 17a. A first return damper 71b, which can be opened and closed, is positioned between the return side of the refrigeration fan 9b and the first opening 12b, and a second return damper 71a, which can be opened and closed, is positioned between the return side of the refrigeration fan 9b and the second opening 17a. Normal refrigeration operation can be performed by opening the first discharge damper 70a and the second return damper 71a, and closing the second discharge damper 70b and the first return damper 71b. Furthermore, by closing the first discharge damper 70a and the second return damper 71a, and opening the second discharge damper 70b and the first return damper 71b, container cooling and refrigeration operation can be performed.

[0042] In the freezer chamber shown in Figure 18B, the discharge side of the refrigeration fan 9b is connected to the first opening 12a and the second opening 17a. A first discharge damper 70a, which can be opened and closed, is positioned between the discharge side of the refrigeration fan 9b and the first opening 12a. The return side of the refrigeration fan 9b is connected to the second opening 17b. By opening the first discharge damper 70a, normal refrigeration operation can be performed. By closing it, container cooling refrigeration operation can be performed.

[0043] Another cooling method using natural convection can be considered. For example, in container cooling and refrigeration operation, the three-way valve 52 is controlled to state 2 (refrigeration mode), the compressor 24 is driven, and the refrigeration evaporator 14b is cooled. At this time, by stopping the refrigeration fan 9b, heat exchange occurs with the refrigeration evaporator 14b, and the cooled air flows into the refrigeration chamber from the refrigeration chamber return port 17 and returns to the refrigeration evaporator chamber 8b from the second refrigeration chamber discharge port 12b. This can create a flow similar to that shown in Figure 7, and the container can be cooled.

[0044] <Operation control in Example 1> Next, while referring to FIGS. 8 to 10, the operation control of the refrigerator of Example 1 will be described. FIG. 8 is a graph showing the temperature change in the freezer compartment in Example 1. In the graph of FIG. 8, the temperature indicates the detected temperature of the freezer compartment temperature sensor 42.

[0045] ≪Operation immediately after the lower freezer door is closed≫ FIG. 9 is a flowchart showing the control immediately after the lower freezer door in Example 1 is closed.

[0046] First, when the lower freezer door 510 as the freezer door is closed and the door sensor detects that the lower freezer door 510 is in the closed state, the control unit drives the compressor 24 at a high rotation speed while rotating the freezer fan 9b in the reverse direction at a rotation speed Na, and starts the container cooling refrigeration operation (second cooling operation) (step S101). Next, the control unit determines whether or not a predetermined time ta has elapsed since the start of the container cooling refrigeration operation (step S102). In step S102, if it is determined that the predetermined time ta has elapsed, the control unit rotates the freezer fan 9b in the forward direction at a rotation speed Nb and starts the normal refrigeration operation (first cooling operation) (step S103). As described above, since a higher flow rate is easily obtained during the forward rotation of the freezer fan 9b than during the reverse rotation, the absolute value of the rotation speed Nb may be set lower than the absolute value of the rotation speed Na. Next, the control unit determines whether or not a predetermined time tb has elapsed since the start of the normal refrigeration operation (step S104). In step S104, if it is determined that the predetermined time tb has elapsed, the control unit stops the freezer fan 9b (step S105. Fan stop operation). In this case, the compressor may be stopped, or a refrigeration operation may be performed to cool the refrigerator compartment by driving the compressor. In the case where only the predetermined time tb has elapsed, the compressor is stopped. When the temperature detected by the refrigerator compartment temperature sensor 41 becomes equal to or higher than a predetermined temperature Ta after the elapse of the predetermined time tb, or even before the elapse, if the temperature becomes equal to or higher than the predetermined temperature Ta, the refrigeration operation may be performed until the temperature detected by the refrigerator compartment temperature sensor 41 becomes equal to or lower than a predetermined temperature Tb. However, Ta > Tb. Also, it is preferable that ta < tb.

[0047] By stopping the refrigeration fan 9b and the compressor, or by performing refrigeration operation as needed, power consumption can be reduced while maintaining a low temperature at the bottom of the freezer compartment through natural convection. In other words, by deliberately creating a temperature bias in the freezer compartment through natural convection, the low temperature at the bottom of the freezer compartment can be maintained.

[0048] Subsequently, the control unit determines whether a predetermined time tc has elapsed since the refrigeration fan 9b stopped (step S106). If it is determined in step S106 that the predetermined time tc has elapsed, the control unit determines whether the temperature detected by the freezer chamber temperature sensor 42 has fallen below a predetermined temperature Tc (step S107). If the detected temperature is higher than the predetermined temperature Tc, the control unit returns to step S101 and restarts the container cooling refrigeration operation. After that, the same process as in steps S102 to S106 is performed, and this is repeated until the temperature detected by the freezer chamber temperature sensor 42 falls below the predetermined temperature Tc in step S107. If it is determined in step S107 that the detected temperature is below the predetermined temperature Tc, the control unit waits until the detected temperature rises above a predetermined temperature Td (step S108), then returns to step S101 and restarts the container cooling refrigeration operation.

[0049] ≪Operation when the freezer compartment is in a stable state≫ Figure 10 is a flowchart showing the control when the freezer compartment is in a stable state in Example 1. The freezer compartment is in a stable state when all the refrigerator doors 210, 310, 410, 510, and 610 remain closed, and the compressor 24 is repeatedly driven and stopped, causing the fluctuation range of the temperature detected by the freezer compartment temperature sensor 42 to fall within a predetermined range (between a predetermined temperature Tc and a predetermined temperature Td).

[0050] First, during normal refrigeration operation, the control unit determines whether the temperature detected by the freezer compartment temperature sensor 42 has fallen below a predetermined temperature Tc (step S201). If the control unit determines that the temperature detected by the freezer compartment temperature sensor 42 is below a predetermined temperature Tc, it stops the refrigeration fan 9b (step S202). At this time, for example, if the temperature detected by the refrigerator compartment temperature sensor 41 is above a predetermined temperature Ta, the control unit performs refrigeration operation by reducing the rotation speed of the compressor 24 and stopping the refrigeration fan 9b. If the detected temperature is below the predetermined temperature Ta and a predetermined time has elapsed since the previous defrosting operation, the compressor 24 and the refrigeration fan 9b are stopped and a defrosting operation of the refrigeration evaporator is performed. If the detected temperature is below the predetermined temperature Ta and a predetermined time has not elapsed since the previous defrosting operation, the compressor 24 and the refrigeration fan 9b are stopped.

[0051] Subsequently, the control unit determines whether the temperature detected by the freezer chamber temperature sensor 42 has reached or exceeded a predetermined temperature Td (step S203). If it is determined that the temperature detected by the freezer chamber temperature sensor 42 is at or above the predetermined temperature Td, the control unit drives the compressor 24 at high speed and rotates the refrigeration fan 9b in the reverse direction at a rotational speed Na to start the container cooling refrigeration operation (step S204). However, if the refrigeration evaporator defrosting operation was performed in step S202, this can be replaced with normal refrigeration operation.

[0052] Next, the control unit determines whether a predetermined time tc has elapsed since the start of the container cooling refrigeration operation (step S205). If it is determined in step S205 that the predetermined time tc has elapsed, the control unit maintains the compressor 24 at high speed and rotates the refrigeration fan 9b in the forward direction at a rotational speed Nb to start normal refrigeration operation (step S206). Thereafter, the processes of steps S201 to S206 are repeated.

[0053] Thus, when the freezer compartment is in a stable state, the control unit repeatedly performs the following operations in this order: fan stop operation, which stops the refrigeration fan 9b to allow natural convection of the air inside the freezer compartment; container cooling refrigeration operation; and normal refrigeration operation.

[0054] <Frost on food in the comparative example> As a comparative example, we will explain the frost formation on food when only normal freezing is performed and no container cooling freezing operation is performed. The temperature of frozen food is determined by heat transfer from the air inside the package and heat conduction from the container. When freezing is not performed and the freezing fan is stopped, the air inside the freezer compartment moves downward due to natural convection, so the temperature distribution inside the freezer compartment is colder at the bottom. In this state, when normal freezing is started, an airflow as shown by the thick arrow in Figure 6 occurs, so the relatively hot air at the top moves downward and heats the container inside the freezer compartment as it flows into the freezing evaporator compartment 8b via the freezer compartment return port 17. Therefore, food located relatively low in the container inside the freezer compartment (especially food on the bottom surface of the lower container 503 in the lower freezer compartment) is affected by the temperature rise of the container due to the heat conduction from the container mentioned above, and is therefore prone to temperature rise immediately after the start of freezing.

[0055] Figure 11 is a graph showing the temperature changes (stable state) of food and ambient air in a comparative example. Here, frozen food packaged in a package is stored in the lower container 503 of the lower freezer compartment, and the freezer compartment is assumed to be in a stable state. The frozen food temperature (dashed line) is the temperature of the surface of the frozen food, and the ambient air temperature (solid line) is the temperature of the air inside the package. The temperature of the lower container 503 of the lower freezer compartment is shown by the dashed line.

[0056] First, as shown in Figure 11, the ambient air temperature decreases immediately after the start of normal refrigeration operation. The main reason for this is that when normal refrigeration operation starts, cold air comes into contact with the package, and as the package cools, the air inside it also cools relatively quickly.

[0057] On the other hand, the temperature of the frozen food and the lower container 503 of the lower freezer compartment rise temporarily immediately after the start of normal freezing operation, as shown in Figure 11. The main reasons for this are presumed to be as follows: The first reason is that because frozen food changes temperature more slowly than air, the effects of the temperature rise before the start of normal freezing operation remain for a while even after normal freezing operation has started. The second reason is that, as mentioned above, immediately after the start of normal freezing operation, the relatively high temperature air moves downward, causing the lower container 503 of the lower freezer compartment to heat up, and thus the temperature of the frozen food rises.

[0058] Furthermore, comparing the temperature of the frozen food with the ambient air temperature reveals that the temperature of the frozen food remains higher than the ambient air temperature. This temperature difference causes moisture to sublimate easily from the food surface, and this sublimated moisture adheres to the inside of the packaging as frost. If this process is repeated, the frozen food dries out.

[0059] <Effects of Example 1> Next, we will explain the effects of Example 1, specifically the effect of suppressing frost formation on frozen foods. Figure 12 is a graph showing the temperature changes (stable state) of frozen food and ambient air in Example 1. Here again, we assume that the frozen food packaged in the package is stored in the lower container 503 of the lower freezer compartment, and that the freezer compartment is in a stable state. The frozen food temperature (dashed line) is the temperature of the food surface, and the ambient air temperature (solid line) is the temperature of the air inside the package. The temperature of the lower container 503 of the lower freezer compartment is shown by the dashed line.

[0060] First, as shown by the solid line in Figure 12, the ambient air temperature decreases immediately after the start of the container cooling refrigeration operation. However, the temperature decrease is more gradual compared to the comparative example. This is because the main target of cooling in the container cooling refrigeration operation is the wall surface, especially the bottom surface, of the lower container 503 in the lower freezer compartment, and the container cooling refrigeration operation is inferior to normal refrigeration operation in terms of cooling the air in the storage space of the lower container 503 in the lower freezer compartment.

[0061] On the other hand, the temperature of the frozen food and the lower container 503 in the lower freezer compartment do not rise immediately after the start of the container cooling refrigeration operation, as shown by the dashed line in Figure 12. The main reasons for this are presumed to be as follows: The first reason is that the bottom surface of the container is rapidly cooled by the container cooling refrigeration operation, so the frozen food is mainly cooled by heat conduction from the container, and the bottom surface of the food, which is closer to the bottom surface of the container, cools more rapidly than the air inside the package. The second reason is that immediately after the start of the container cooling refrigeration operation, unlike immediately after the start of normal refrigeration operation, the air in the upper part of the freezer compartment, which has become relatively hot due to natural convection when the fan is stopped, does not move downward.

[0062] Furthermore, comparing the temperature of frozen food with the ambient air temperature reveals that the temperature of frozen food remains lower than the ambient air temperature. This is because, as the container cools down, the frozen food is relatively more strongly affected by heat conduction from the container, bypassing the air inside the package. As a result, moisture sublimes less easily from the surface of the frozen food, and frost formation on the inside of the package is suppressed. Consequently, drying of the frozen food is reduced, making it possible to maintain the quality of the frozen food.

[0063] In other words, when the freezer compartment is in a stable state, it is effective for the control unit to control the compressor 24 and the refrigeration fan 9b to maintain a temperature such that the average temperature of the entire bottom surface of the lower container 503 in the lower freezer compartment is lower than the average temperature of the air inside the storage space of the lower container 503 in the lower freezer compartment. One example of how this can be achieved is to perform a container cooling refrigeration operation immediately after switching from fan-stop operation (refrigeration operation, etc.) to refrigeration operation, thereby cooling the lower container 503 itself and promoting the cooling of the food. Another example is that when cooling the freezer compartment 7, the above-mentioned normal refrigeration operation may be omitted or partially omitted, and only the container cooling refrigeration operation may be performed. It is desirable that the relationship in which the temperature of the container bottom surface is lower than the temperature of the air inside the container storage space is always maintained, but a temporary reversal of the temperature relationship is permissible. Therefore, if the time-averaged temperature when the freezer compartment is in a stable state is such that the temperature of the container bottom surface is lower than the temperature of the air inside the container storage space, the aforementioned frost suppression effect can be expected.

[0064] <Modified Example 1> The container cooling refrigeration operation in Example 1 was performed to particularly efficiently cool the lower container 503 (first container) of the lower freezer compartment, which has the largest storage space among the multiple containers in the freezer compartment. However, similar effects can be expected for containers that are cooled more efficiently than in normal refrigeration operation. Furthermore, the cooling efficiency of the middle container 502 (second container) and the upper container 501 (third container) of the lower freezer compartment can be increased during container cooling refrigeration operation by forming a third air passage that guides air in the front-to-back direction (from front to back) in these containers. The third air passage can be, for example, a hollow cylindrical structure 60 provided on the underside of the bottom surface of the second and third containers, with holes on the front and rear sides (see Figure 19). Preferably, the bottom surface of the structure 60 does not have an opening large enough to allow cold air to fall downwards, and plays a role in promoting the airflow shown by the thick arrow in Figure 7. Furthermore, metal plates such as aluminum plates may be placed on the bottom of the second and third containers to efficiently cool the food stored in these containers.

[0065] Furthermore, as a container cooling and freezing operation, in addition to the aforementioned method of blowing air so that cold air can easily hit the third container, a method may also be used in which the refrigeration fan 9b is stopped and the three-way valve 52 is set to state 2 (freezing mode) to drive the compressor 24. Even when using this method, it is possible to keep the bottom surface temperature of the third container lower than the internal air temperature of the storage space of the third container by natural convection, and as a result, evaporation of moisture from the food surface inside the third container can be suppressed.

[0066] Furthermore, in the operation control of Embodiment 1 described using Figure 9 or Figure 10 above, the timing of switching from container cooling / freezing operation to normal freezing operation was determined by the time elapsed since the start of container cooling / freezing operation. However, other methods may be used instead. For example, a temperature sensor that directly measures the temperature of the container can be installed, and the system can switch from container cooling / freezing operation to normal freezing operation based on the temperature detected by the temperature sensor. Container cooling / freezing operation is performed when the temperature of the container rises, and normal freezing operation is performed when the temperature falls. [Examples]

[0067] As mentioned above, in the period immediately after switching from fan-stopped operation (refrigeration operation, etc.) to freezing operation, the food temperature tends to be higher than the ambient air temperature. In particular, after food is put in or taken out with the freezer door open, relatively hot air from outside flows into the freezer compartment, and the aforementioned normal freezing operation is mainly performed, so the food temperature tends to be higher than the ambient temperature. Therefore, in Example 2, by controlling the cooling capacity of the freezer to gradually increase immediately after the freezer door is closed, the time during which the food temperature exceeds the ambient air temperature is minimized, thereby suppressing frost formation on the food.

[0068] <Operation control in Example 2> Next, the operation control of the refrigerator in Example 2 will be described with reference to Figures 13 and 14. Figure 13 is a graph showing the temperature change inside the freezer compartment immediately after the lower freezer compartment door is closed in Example 2. Note that the temperature in the graph in Figure 13 represents the temperature detected by the freezer compartment temperature sensor 42. In Example 2, the cooling power of the freezer compartment is increased in three stages by gradually increasing the rotation speed of the compressor 24 and the refrigeration fan 9b in three stages. In this example, control such as the first refrigeration operation is started in response to the detection of a closed door by the door sensor that detects the opening and closing of the freezer compartment door 7. However, it may also be started in response to the detection of an increase in the value detected by the freezer compartment temperature sensor 42, for example, when it rises to a threshold that serves as the basis for starting normal refrigeration operation or container cooling refrigeration operation. Figure 14 is a flowchart showing the control immediately after the lower freezer door is closed in Example 2.

[0069] First, when the lower freezer door 510 is closed and the door sensor detects that the lower freezer door 510 is in the closed state (step S301), the control unit drives the compressor 24 at a first rotational speed n1 and rotates the refrigeration fan 9b in the forward direction at a first rotational speed N1 to start the first refrigeration operation (step S302). Next, the control unit determines whether a predetermined time t1 has elapsed since the start of the first refrigeration operation, or whether the temperature detected by the freezer temperature sensor 42 has fallen below a first predetermined temperature T1 (step S303).

[0070] In step S303, if it is determined that a predetermined time t1 has elapsed or the temperature has fallen below the first predetermined temperature T1, the control unit drives the compressor 24 at a second rotational speed n2 that is higher than the first rotational speed n1, and rotates the refrigeration fan 9b in the forward direction at a rotational speed N2 that is higher than the first rotational speed N1, and starts the second refrigeration operation (step S304). Next, the control unit determines whether a predetermined time t2 has elapsed since the start of the second refrigeration operation, or whether the temperature detected by the refrigeration chamber temperature sensor 42 has fallen below the second predetermined temperature T2 (step S305).

[0071] In step S305, if it is determined that a predetermined time t2 has elapsed or the temperature has fallen below the second predetermined temperature T2, the control unit drives the compressor 24 at a third rotational speed n3 that is higher than the second rotational speed n2, and rotates the refrigeration fan 9b in the forward direction at a third rotational speed N3 that is higher than the second rotational speed N2, and starts the third refrigeration operation (step S306). Next, the control unit determines whether a predetermined time t3 has elapsed since the start of the third refrigeration operation, or whether the temperature detected by the refrigeration chamber temperature sensor 42 has fallen below the third predetermined temperature T3 (step S307).

[0072] In step S307, if it is determined that a predetermined time t3 has elapsed or the temperature has fallen below the third predetermined temperature T3, the control unit reduces the cooling force by lowering the rotation speed of the refrigeration fan 9b or the rotation speed of the compressor 24, or stops the rotation of the refrigeration fan 9b to stop the refrigeration operation (step S308). If the third predetermined temperature T3 or lower is a threshold value that serves as the criterion for ending normal refrigeration operation and / or container cooling refrigeration operation, or a value below that, it is preferable to stop the refrigeration operation.

[0073] In the aforementioned Example 2, an example was described in which both the compressor 24 and the refrigeration fan 9b are switched to high-speed rotation in three stages, but it may also be two stages or four or more stages. Furthermore, the number of switching stages for one of the compressor 24 and the refrigeration fan 9b may be less than the number of switching stages for the other, or the rotation speed of one of them may be kept constant without switching.

[0074] <Frost on food in the comparative example> As a comparative example, we will describe the frost formation on food when the compressor and refrigeration fan are immediately driven at high speed (the third rotational speed mentioned above) immediately after the lower freezer door is closed. Figure 15 is a graph showing the temperature changes of the food and ambient air (immediately after closing the door) in the comparative example. Note that the food temperature (dashed line) is the temperature of the food surface, and the ambient air temperature (solid line) is the temperature of the air inside the package.

[0075] As shown in Figure 15, both the ambient air and the food temperature rise when the door is opened and closed, with the ambient air temperature being slightly higher at that time. However, the ambient air temperature decreases faster after the door is closed. This is because air changes temperature more quickly than food. As a result, the ambient air temperature falls below the food temperature relatively quickly after the door is closed. If this condition persists for a long time, the amount of moisture evaporating from the food surface increases, and the amount of frost accumulating on the inside of the package also increases.

[0076] <Effects of Example 2> Next, we will explain the effects of Example 2, particularly the effect of suppressing frost formation on food. Figure 16 is a graph showing the temperature changes of the food and ambient air (immediately after closing the door) in Example 2. Here again, the food temperature (dashed line) is the temperature of the food surface, and the ambient air temperature (solid line) is the temperature of the air inside the package.

[0077] As shown in Figure 16, similar to the comparative example, both the ambient air and the food temperature rise when the door is opened and closed, the ambient air temperature is slightly higher at that time, and the ambient air temperature decreases faster after the door is closed. However, in Example 2, the temperature decrease rate for both the ambient air and the food is slower than in the comparative example. As a result, it takes a relatively long time after the door is closed for the ambient air temperature to fall below the food temperature, that is, for moisture to easily evaporate from the food surface. Therefore, compared to the comparative example, the amount of moisture evaporating from the food decreases, and the amount of frost adhering to the inside of the package also decreases.

[0078] Furthermore, according to Example 2, effects other than the suppression of frost formation on food can also be expected. For example, in Example 2, the initial cooling force is weaker than that of the comparative example, so the freezing operation time is longer than that of the comparative example. However, since the initial rotation speed of the compressor 24 and the freezing fan 9b can be lower, the overall power consumption can be reduced compared to the comparative example.

[0079] <Modified Example 2> In the operation control of Example 2, the cooling force of the freezer compartment was increased in three stages, but it is also possible to include a state in between where no cooling force is applied or a state where the cooling force is weaker than the previous state. Figure 17 is a graph showing the temperature change inside the freezer compartment immediately after the lower freezer compartment door is closed in a modified example of Example 2. Note that the temperature in the graph of Figure 17 represents the temperature detected by the freezer compartment temperature sensor 42.

[0080] In this modified example, during the second refrigeration operation, the refrigeration fan 9b is driven, but the compressor 24 is stopped. Therefore, although the refrigeration operation time is longer compared to Example 2, the power consumption of the compressor 24 can be significantly reduced, making it possible to reduce the overall power consumption compared to Example 2.

[0081] Thus, from the viewpoint of ensuring that the temperature decrease of the frozen food is not too slow compared to the decrease in ambient air temperature, it is sufficient to maintain a state in which the ambient air temperature is higher until the temperature of the frozen food generally reaches the target temperature (Tc), for example, until it reaches a temperature 5°C higher than Tc, preferably 3°C higher than Tc. Another variation is to alternately increase the cooling force once or twice or more from the initial cooling force, and then immediately decrease it once or twice or more.

[0082] <Other examples> The above are examples, but the present invention is not limited to the embodiments described above and includes various modifications. For example, in the embodiments described above, the configuration included two evaporators (coolers), but there may be only one evaporator (cooler). Also, in the embodiments described above, the containers housed in the lower freezer compartment were in three stages: an upper container, a middle container, and a lower container, but there may be two stages: an upper container and a lower container, or even one stage.

[0083] This invention encompasses the following technical concepts. [Note 1] A refrigeration cycle including a compressor and a cooler, A cooler chamber housing the aforementioned cooler, A freezer compartment that opens at the front, A freezer door that opens and closes the aforementioned opening, A door sensor that detects the open / closed state of the freezer door or a temperature sensor placed inside the freezer compartment, A control unit controls the cooling capacity of the freezer compartment to gradually increase after the door sensor detects that the freezer compartment door is closed, or after the temperature sensor detects an increased temperature. A refrigerator equipped with [a specific feature]. [Note 2] In Appendix 1, A cooling fan that blows the air cooled by the aforementioned cooler into the freezer chamber, The door sensor and the temperature sensor for detecting the temperature inside the freezer compartment are further included. When the door sensor detects that the freezer door is closed or that the temperature sensor's detected value has increased, the control unit drives the refrigeration fan at a first rotational speed, A refrigerator characterized in that, when the temperature sensor detects that the temperature inside the freezer compartment has dropped to a predetermined temperature, the control unit drives the freezer fan at a second rotational speed higher than the first rotational speed. [Note 3] In Appendix 1, The system further includes a cooling fan that blows the air cooled by the aforementioned cooler into the freezer chamber. When the door sensor detects that the freezer door is closed or that the temperature sensor's detected value has increased, the control unit drives the refrigeration fan at a first rotational speed, A refrigerator characterized in that, after a predetermined time has elapsed, the control unit drives the refrigeration fan at a second rotational speed higher than the first rotational speed. [Note 4] In Appendix 1, The door sensor and the temperature sensor for detecting the temperature inside the freezer compartment are further included. When the door sensor detects that the freezer door is closed or that the temperature sensor's detected value has increased, the control unit drives the compressor at a first rotational speed, A refrigerator characterized in that, when the temperature sensor detects that the temperature inside the freezer compartment has dropped to a predetermined temperature, the control unit drives the compressor at a second rotational speed higher than the first rotational speed. [Note 5] In Appendix 1, When the door sensor detects that the freezer door is closed or that the temperature sensor's detected value has increased, the control unit drives the compressor at a first rotational speed, A refrigerator characterized in that, after a predetermined time has elapsed, the control unit drives the compressor at a second rotational speed higher than the first rotational speed. [Note 6] In Appendix 1, The system further includes a cooling fan that blows the air cooled by the aforementioned cooler into the freezer chamber. A refrigerator characterized in that, when the door sensor detects that the freezer door is closed or that the temperature sensor's detected value has increased, the control unit controls the rotation speed of the refrigeration fan and the compressor to gradually increase. [Note 7] In Appendix 6, A refrigerator characterized in that the process of gradually increasing the rotational speed of the refrigeration fan and the compressor includes a state in which the refrigeration fan is running while the compressor is stopped. [Explanation of Symbols]

[0084] 1...Refrigerator, 2...Refrigerator compartment, 3...Ice maker compartment, 4...Upper freezer compartment, 5...Lower freezer compartment, 6...Vegetable compartment, 7...Freezer compartment, 8a...Refrigerator evaporator compartment, 8b...Freezer evaporator compartment, 9a...Refrigerator fan, 9b...Freezer fan, 10...Refrigerator body, 10a...Outer box, 10b...Inner box, 11...Refrigerator compartment air duct, 11a...Refrigerator compartment outlet, 12...Freezer compartment air duct, 12a...First freezer compartment outlet, 12b...Second freezer compartment outlet, 13...Vegetable compartment air duct, 13a...Vegetable compartment outlet, 14a...Refrigerator evaporator, 14b...Freezer evaporator, 15a,15b,15c...Refrigerator return port, 17...Freezer return port, 18...Vegetable compartment return air duct, 18a... 19...Vegetable compartment return opening, 24...Vegetable compartment damper, 25...Vacuum insulation material, 28, 29, 30...Insulated partition wall, 40a...Refrigerator evaporator temperature sensor, 40b...Freezer evaporator temperature sensor, 41...Refrigerator compartment temperature sensor, 42...Freezer compartment temperature sensor, 43...Vegetable compartment temperature sensor, 210a, 210b...Refrigerator compartment door, 301...Ice maker container, 310...Ice maker compartment door, 401...Upper freezer compartment container, 410...Upper freezer compartment door, 501...Lower freezer compartment upper container, 502...Lower freezer compartment middle container, 503...Lower freezer compartment lower container, 510...Lower freezer compartment door, 601...Vegetable compartment upper container, 602...Vegetable compartment lower container, 610...Vegetable compartment door

Claims

1. A refrigeration cycle including a compressor and a cooler, A cooler chamber housing the aforementioned cooler, The first container is housed in a freezer compartment with an opening at the front, The opening of the freezer compartment is provided with a freezer compartment door that can be opened and closed, The system includes a cooling fan that blows the air cooled by the cooler into the freezer chamber, A first cooling operation in which cold air is sent into the storage space of the first container, A second cooling operation in which cold air is sent toward the bottom surface of the first container, The fan stop operation, which stops the aforementioned refrigeration fan, A refrigerator characterized by repeated operation.

2. In the refrigerator according to claim 1, A refrigerator in which, in a stable state, the time-averaged temperature of the bottom surface of the first container is lower than the time-averaged temperature of the air in the storage space of the first container.

3. In the refrigerator according to claim 1 or 2, A first air passage connecting the first opening of the freezer chamber and the cooler chamber, The system further comprises a second air passage connecting the second opening of the freezer chamber and the cooler chamber, wherein the first opening is arranged to include the area above the opening of the first container. The second opening is located below the opening of the first container, and the rotation direction of the refrigeration fan is reversed between the first cooling operation, which sends cold air towards the storage space of the first container, and the second cooling operation, which sends cold air towards the bottom surface of the first container. During the first cooling operation, the air cooled by the cooler is supplied to the freezer chamber through the first air passage and the first opening. A refrigerator characterized in that, during the second cooling operation, the air cooled by the cooler is supplied to the freezer compartment through the second air passage and the second opening.

4. In the refrigerator according to claim 3, A refrigerator characterized in that, during the second cooling operation, the refrigeration fan rotates at a higher rotational speed than during the first cooling operation.

5. In the refrigerator according to claim 3, A separate storage room for storing food at a different temperature range than the aforementioned freezer, Another air passage connecting the other storage chamber and the first air passage, A damper is provided in the other air passage, A refrigerator characterized by closing the damper during the second cooling operation.

6. In the refrigerator according to claim 1 or 2, A first opening and a second opening communicating with the discharge side of the aforementioned refrigeration fan, The second opening is connected to the return side of the aforementioned cooling fan, The system includes one or more dampers whose opening and closing are switched between a first cooling operation that sends cold air into the storage space of the first container and a second cooling operation that sends cold air towards the bottom surface of the first container, In the case of the first cooling operation and the case of the second cooling operation, the rotation direction of the cooling fan is the same. During the first cooling operation, at least the air cooled by the cooler is supplied to the freezer chamber through the first opening which is connected to the discharge side of the refrigeration fan. A refrigerator characterized in that, during the second cooling operation, the air cooled by the cooler is supplied to the freezer compartment through the second opening which is connected to the discharge side of the refrigeration fan.

7. In the refrigerator according to claim 1 or 2, A refrigerator characterized in that, after a fan stop operation in which the refrigeration fan is stopped, and before a first cooling operation in which cold air is sent towards the storage space of the first container, a second cooling operation is performed in which cold air is sent towards the bottom surface of the first container.

8. In the refrigerator according to claim 1 or 2, The system includes a door sensor that detects the opening and closing of the freezer door, A refrigerator characterized in that, after the door sensor detects that the door is closed, the next cooling of the freezer compartment is performed by sending cold air toward the bottom surface of the first container before performing a first cooling operation which sends cold air toward the storage space of the first container.

9. In the refrigerator according to claim 1 or 2, A refrigerator characterized in that the time of the first cooling operation, in which cold air is sent into the storage space of the first container, is longer than the time of the second cooling operation, in which cold air is sent towards the bottom surface of the first container.

10. In the refrigerator according to claim 1 or 2, In the aforementioned freezer chamber, the second container is positioned above the first container. A refrigerator characterized in that a third air passage for guiding air in the front-to-back direction is formed on the underside of the bottom surface of the second container.

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