JP7650832B2 - refrigerator - Google Patents

Description

This disclosure relates to refrigerators.

Patent Document 1 discloses a refrigerator (Patent Document 1 (0077)) in which the front of the wine chamber supply air duct for cooling the wine chamber is partitioned by a partition body that does not have an air outlet, so that the air flowing through the wine chamber supply air duct does not flow into the wine chamber. Here, the wine chamber is a storage chamber that is a storage space with a higher temperature than the left and right refrigerator chambers (Patent Document 1 (0035)), and it is also disclosed that the refrigerator may be provided with a means for heating the wine chamber, such as an electric heater, and that this can keep the inside of the wine chamber at a temperature higher than room temperature (Patent Document 1 (0087)).

Patent Document 2 discloses a refrigerator in which the refrigerator compartment is cooled by a direct cooling method using a cooling plate, and the freezer compartment is cooled by circulating cold air that has exchanged heat with a freezer evaporator (Patent Document 2 (0064)). It also discloses that by cooling the refrigerator compartment by a direct cooling method, it is possible to maintain a high humidity level inside the refrigerator compartment (Patent Document 2 (0065)), and that by keeping the temperature of the cooling plate above the dew point temperature, condensation on the cooling plate is further suppressed (Patent Document 2 (0066)).

Patent Document 3 discloses a configuration in which a refrigerator equipped with a refrigerator compartment cooled by a direct cooling type refrigerator compartment evaporator and a freezer compartment cooled by an indirect cooling type has a refrigerator compartment evaporator arranged in contact with the wall on the back of the inner box of the refrigerator compartment, and the refrigerator compartment has a cooled wall surface cooled by the refrigerator compartment evaporator (Patent Document 3 (0007), (0032), etc.). It also discloses a configuration in which an open/close damper is opened and closed depending on the temperature of the refrigerator compartment to control the amount of cold air in the freezer compartment or the cold air that has exchanged heat with the freezer compartment evaporator (Patent Document 3 (0042)), and a configuration in which, when frost forms on the refrigerator compartment cooling wall surface, a three-way valve is used to switch to a circuit in which the refrigerant flows through a capillary tube, stopping the cooling of the refrigerator compartment evaporator and defrosting the refrigerator compartment cooling wall surface (Patent Document 3 (0043)).

Patent No. 6766298 JP 2020-180721 A Patent No. 4867758

The wine compartment described in Patent Document 1 is set at a higher temperature than the other refrigerator compartments (e.g., (0035), (0087) in Patent Document 1). For example, the target temperatures for calculating power consumption described in JIS C9801-3:2015 and IEC 62552-3:2015 are 12°C for the wine compartment and 4°C for the refrigerator compartment. Therefore, in the case of the wine compartment, the temperature difference between the storage compartment and the outside air is small, and it is possible to cool the wine compartment even if the cooling capacity required is relatively low. Furthermore, Patent Document 1 does not consider measures against frost and condensation on the partition.

In the refrigerator described in Patent Document 2, when the refrigerator compartment is cooled by a cooling plate, the temperature of the cooling plate is kept above the dew point temperature while keeping the humidity inside the refrigerator compartment high, so the temperature difference between the refrigerator compartment and the cooling plate, which is at or above the dew point temperature, is small, making it difficult to ensure sufficient cooling capacity.

Patent Document 2 describes how the refrigerator compartment can be cooled quickly by an indirect cooling method in which a refrigerator compartment feed damper is opened to send in cooler air from the cooling compartment (Patent Document 2 (0064) and (0065)). However, because the refrigerator compartment is cooled by a direct cooling method to maintain a high humidity level inside the refrigerator compartment, supplementing the cooling capacity with an indirect cooling method will result in a decrease in humidity inside the refrigerator compartment. In this case too, it is difficult to maintain the temperature of the cooling plate above the dew point temperature while maintaining a high humidity level inside the refrigerator compartment. In addition, because the indirect cooling method described above is used to reduce humidity as a method of preventing condensation inside the refrigerator compartment (Patent Document 2 (0066)), it is believed that humidity can only be increased to the extent that condensation or frost inside the refrigerator compartment can be prevented.

The refrigerator described in Patent Document 3 is equipped with a refrigerator compartment that is cooled by a refrigerator compartment evaporator of a direct cooling system, and has a configuration in which the cooling wall surface cooled by the refrigerator compartment evaporator is exposed to the refrigerator compartment. Therefore, if the temperature of the cooling wall surface becomes high enough to cause frost, it is thought that there will be a problem in that food and other items placed near the cooling wall surface of the refrigerator compartment will freeze.

The objective of this disclosure is to cool the refrigerator compartment in a short time, maintain high humidity in the refrigerator compartment, and prevent freezing of food and the like and condensation or frost formation in undesirable areas in the refrigerator compartment in a refrigerator equipped with a cooling plate for cooling the refrigerator compartment.

The refrigerator disclosed herein comprises a refrigerator compartment, a refrigeration cycle in which a compressor, a radiator, a pressure reducing section, and an evaporator are connected in a ring shape by refrigerant piping, a cooling plate with one side facing a first air duct on the refrigerator compartment side, and a refrigerator compartment fan that pressurizes the air in the first air duct, and the other side of the cooling plate is configured to contact a portion of the refrigerant piping from the pressure reducing section to the suction side of the compressor, or to face a second air duct through which cold air cooled by the evaporator flows, and is characterized in that the surface temperature of the cooling plate on the first air duct side is cooled to a temperature lower than the frost point temperature of the refrigerator compartment by the refrigerant flowing through the refrigerant piping or the cold air flowing through the second air duct.

The refrigerator disclosed herein also includes a refrigerator compartment, a refrigeration cycle in which a compressor, a radiator, a pressure reduction section, and an evaporator are connected in a ring shape by refrigerant piping, a cooling plate with one side facing a first air duct on the refrigerator compartment side, and a refrigerator compartment fan that pressurizes the air in the first air duct, and the other side of the cooling plate is configured to contact a portion of the refrigerant piping from the pressure reduction section to the suction side of the compressor, or to face a second air duct through which cold air cooled by the evaporator flows, and is characterized in that frost forms on the first air duct side of the cooling plate by the refrigerant flowing through the refrigerant piping or the cold air flowing through the second air duct.

According to the present disclosure, in a refrigerator provided with a cooling plate for cooling the refrigerator compartment, the refrigerator compartment can be cooled in a short time, the humidity in the refrigerator compartment can be kept high, and the freezing of food and the like in the refrigerator compartment and the formation of condensation or frost in undesirable areas can be prevented.

FIG. 1 is a front view showing a refrigerator according to an embodiment. 2 is a cross-sectional view taken along line AA of FIG. 1. 3 is an exploded perspective view showing a first refrigerator compartment air duct 110 and a second refrigerator compartment air duct 120 of FIG. 2. FIG. 1 is a configuration diagram showing a refrigeration cycle of a refrigerator according to an embodiment. FIG. 2 is a schematic diagram showing an air passage configuration of a refrigerator according to an embodiment. FIG. 2 is a front view showing a direct cooling operation of the refrigerator according to the embodiment. FIG. 2 is a front view showing an indirect cooling operation of the refrigerator according to the embodiment. FIG. 4 is a front view showing an air flow during a first circulation operation of the refrigerator according to the embodiment. 1 is a graph showing an example of a temperature change during a cooling operation of a refrigerator according to an embodiment. 1 is a flowchart showing basic control of a cooling operation of a refrigerator according to an embodiment. FIG. 11 is a configuration diagram showing a refrigeration cycle of a first modified example. FIG. 11 is a configuration diagram showing a refrigeration cycle of a modified example 2. 10 is a schematic diagram showing the configuration around the cooling plate in the first and second modified examples. FIG. 1 is a graph showing an example of a temperature change during a defrosting operation of an evaporator in a refrigerator according to an embodiment. 4 is a flowchart showing basic control of a defrosting operation of an evaporator in the refrigerator according to the embodiment. 1 is a flowchart showing a basic control during a cooling operation of a refrigerator compartment of a refrigerator according to an embodiment.

Below, examples of the present disclosure are described. However, the examples are not limited to the following content in any way, and can be modified as desired without departing from the spirit of the present disclosure.

Figure 1 is a front view showing a refrigerator according to the embodiment. In the following explanation, a six-door refrigerator 1 is used as an example, but the refrigerator is not limited to six doors.

As shown in the figure, the insulated box 10 of the refrigerator 1 has storage compartments in the following order from the top: refrigerator compartment 2, ice-making compartment 3 on the left and right, upper freezer compartment 4, lower freezer compartment 5, and vegetable compartment 6. The refrigerator 1 has doors that open and close the openings of each storage compartment. These doors are refrigerator compartment doors 2a, 2b, ice-making compartment door 3a, upper freezer compartment door 4a, lower freezer compartment door 5a, and vegetable compartment door 6a. The refrigerator compartment doors 2a, 2b are double doors, while the ice-making compartment door 3a, upper freezer compartment door 4a, lower freezer compartment door 5a, and vegetable compartment door 6a are pull-out doors.

To secure the refrigerator compartment doors 2a and 2b to the refrigerator 1, door hinges (not shown) are provided at the top and bottom of the refrigerator compartment 2, and the top door hinge is covered with a hinge cover 16.

Refrigerator compartment 2 and vegetable compartment 6 are refrigerated storage compartments whose interior is basically controlled to the refrigeration temperature range (above 0°C); for example, refrigerator compartment 2 is controlled to about 2°C, and vegetable compartment 6 to about 6°C. Ice-making compartment 3, upper freezer compartment 4, and lower freezer compartment 5 make up freezer compartment 7 (freezer storage compartment) whose interior is controlled to the freezing temperature range (below 0°C). It is desirable for freezer compartment 7 to be controlled to, for example, an average of about -20°C.

The refrigerator compartment 2 is separated from the ice-making compartment 3 and the upper freezer compartment 4 by an insulated partition wall 27. The lower freezer compartment 5 and the vegetable compartment 6 are separated by an insulated partition wall 28. In addition, insulated partition walls 29 and 30 are provided on the front side between the ice-making compartment 3 and the upper freezer compartment 4 and the lower freezer compartment 5. The insulated partition wall 30 is intended to prevent cold air from leaking out of the refrigerator 1 through the gaps in the doors 3a, 4a, and 5a, and to prevent air from the outside from entering each storage compartment.

Figure 2 is a cross-sectional view taken along line A-A in Figure 1.

As shown in FIG. 2, the refrigerator 1 is configured with the outside and inside separated by an insulated box 10 formed by filling a space between an outer box 10a (made of steel plate) and an inner box 10b (made of synthetic resin) with a foam insulation material (e.g., urethane foam). In addition to the foam insulation material, vacuum insulation material 25, which has a lower thermal conductivity than the foam insulation material, is arranged between the outer box 10a and the inner box 10b of the insulated box 10, thereby improving the insulation performance without reducing the food storage volume. Here, the vacuum insulation material is composed of a core material such as glass wool or urethane wrapped in an outer packaging material. The outer packaging material contains a metal layer (e.g., aluminum) to ensure gas barrier properties.

The vacuum insulation material 25 is arranged on the left and right walls and the rear wall of the freezer compartment 7 to insulate the periphery of the freezer compartment 7, which is the coldest compartment in the insulated box. The vacuum insulation material 25 on the rear wall is arranged so as to cover approximately the rear of the second refrigerator compartment air duct 120 of the refrigerator compartment 2, which will be described later (see Figures 6A and 6B). The vacuum insulation material 25 is also arranged on the door 5a of the lower freezer compartment 5, which is a relatively large freezer storage compartment, in order to improve the insulation performance.

To prevent the vegetable compartment 6 from becoming too cold, an electric heater 46 is provided at the bottom of the insulating partition wall 28 to heat the vegetable compartment 6.

The refrigerator compartment doors 2a and 2b are provided with multiple door pockets 33a, 33b, and 33c on the inside of the compartment. The refrigerator compartment 2 is divided into multiple storage spaces by shelves 34a, 34b, 34c, and 34d. A low-temperature storage space 36 is provided in the lower part of the refrigerator compartment 2 (above the heat-insulating partition wall 27). The inside of the low-temperature storage space 36 is controlled to about -1°C. This temperature is particularly low within the refrigerator compartment 2. An openable and closable lid 36a is provided in front of the low-temperature storage space 36. This keeps the low-temperature storage space 36 at a low temperature and high humidity without allowing the cold air from the refrigerator compartment 2 to directly enter. For this reason, the low-temperature storage space 36 is particularly suitable as a space for storing foods (such as meat and fish) that require low temperatures and reduced drying.

The ice-making compartment 3, upper freezer compartment 4, lower freezer compartment 5, and vegetable compartment 6 are provided with ice-making compartment container 3b, upper freezer compartment container 4b, lower freezer compartment container 5b, and vegetable compartment container 6b, which are pulled out together with the doors 3a, 4a, 5a, and 6a, respectively.

The evaporator chamber 8 is provided at the rear of the lower freezer chamber 5. The evaporator chamber 8 is provided with an evaporator 14. Here, the area below the evaporator 14 is called the evaporator chamber 8a, and the area above the evaporator 14 is called the evaporator chamber 8b. An evaporator fan 9a is provided at the top of the evaporator chamber 8b. The cold air generated by the evaporator 14 is sent upward by the evaporator fan 9a. Therefore, of the evaporator chambers 8, the evaporator chamber 8a is downstream of the air flow of the evaporator 14, and the evaporator chamber 8b is upstream of the air flow of the evaporator 14. The evaporator fan 9a needs to have a large amount of air to blow to all of the storage chambers, the refrigerator chamber 2, the freezer chamber 7, and the vegetable chamber 6. For this reason, a propeller fan, which is an axial fan that can obtain a large amount of air, is used as the evaporator fan 9a.

A freezer compartment air duct 100 is provided in the blowing area of the evaporator fan 9a. The freezer compartment air duct 100 is provided with an ice-making compartment outlet 101, an upper freezer compartment outlet 102, and a lower freezer compartment outlet 103 that supply cool air to the front ice-making compartment 3, the upper freezer compartment 4, and the lower freezer compartment 5, respectively.

A freezer compartment return air duct 105 is provided in front of the evaporator chamber 8a. Return air from the ice making chamber 3, upper freezer compartment 4, and lower freezer compartment 5 flows through the freezer compartment return air duct 105. The freezer compartment return air duct 105 is formed with a width approximately equal to the width of the evaporator 14. This allows the return air to flow efficiently into the evaporator 14.

A defrost heater 21 for heating the evaporator 14 is provided at the bottom of the evaporator chamber 8. The defrost heater 21 is, for example, a 50W to 200W electric heater, and is the heater with the highest heat generation in the refrigerator 1. In the example shown in the figure, it is a 150W radiant heater. In order to melt the frost on the evaporator 14, the refrigerator 1 performs a defrosting operation in which the defrost heater 21 is energized while the compressor 24 is stopped to heat the evaporator 14 and the frost on it. The defrosted water (melted water) generated when the evaporator 14 is defrosted falls into the evaporator gutter 23 provided at the bottom of the evaporator chamber 8, and is discharged through the evaporator drain outlet 22 and the evaporator drain pipe 127 into the evaporator tray 32 provided above the compressor 24 in the machine room 39. The defrosted water that flows into the evaporator tray 32 evaporates due to the heat radiation from the compressor 24 and the ventilation by the machine room fan (not shown).

A first refrigerator compartment air duct 110 is provided on the rear side of the refrigerator compartment 2. A refrigerator compartment fan 9b is installed at the bottom of the first refrigerator compartment air duct 110. The refrigerator compartment fan 9b uses a centrifugal turbofan that is easy to install in a narrow air duct in order to circulate air within the refrigerator compartment 2 in a relatively narrow air duct.

The first refrigerator compartment air duct 110 is provided with refrigerator compartment outlets 111a, 111b, which blow air into the refrigerator compartment 2, above the top shelf 34a and in the space between shelf 34a and the second-highest shelf 34b.

Behind the first refrigerator compartment air duct 110, there is provided an adjacent refrigerator compartment second air duct 120 separated by a partition wall. The partition wall provided between the first refrigerator compartment air duct 110 and the second refrigerator compartment air duct 120 is a cooling plate 200. The air in the first refrigerator compartment air duct 110 and the air in the second refrigerator compartment air duct 120 are heat exchanged via the cooling plate 200. In this example, the opening area of the refrigerator compartment outlet 111a is 1000 ^mm2 , and the opening area of the refrigerator compartment outlet 111b is 500 ^mm2 , making the opening area of the uppermost outlet larger.

The cross-sectional thickness of the first and second refrigerator air ducts 110 and 120, i.e., the dimension of the flow path in the depth direction in the refrigerator 1, is preferably 5 to 20 mm each in terms of ventilation resistance and space saving.

A vegetable compartment return port 136 is provided in the insulating partition wall 28 at the top of the vegetable compartment 6, and air from the vegetable compartment 6 flows into the lower part of the evaporator chamber 8 via the vegetable compartment return air duct 135.

A first refrigerator damper 151 is provided at the bottom of the first refrigerator air duct 110, and a second refrigerator damper 152 is provided at the bottom of the second refrigerator air duct 120. The first refrigerator damper 151 and the second refrigerator damper 152 are cold air blocking means. The first refrigerator damper 151 and the second refrigerator damper 152 may be formed integrally, or may be configured to be driven by a single motor. A component that combines the functions of the first refrigerator damper 151 and the second refrigerator damper 152 is called the "refrigerator damper."

The refrigerator compartment 2, freezer compartment 7, and vegetable compartment 6 are provided with a refrigerator compartment temperature sensor 41, a freezer compartment temperature sensor 43, and a vegetable compartment temperature sensor 44 on the rear side of the interior of the compartment, respectively. In addition, an evaporator temperature sensor 40 is provided on the top of the evaporator 14, and a cooling plate temperature sensor 201 is provided on the top of the cooling plate 200. These sensors detect the temperatures of the refrigerator compartment 2, freezer compartment 7, vegetable compartment 6, evaporator 14, and cooling plate 200. In addition, an outside air temperature sensor 37 that detects the temperature of the outside air (outside the compartment air) and an outside air humidity sensor 38 that detects the humidity of the outside air are provided inside the hinge cover 16. Other sensors include door sensors (not shown) that detect the open/closed state of the doors 2a, 2b, 3a, 4a, 5a, and 6a, and an ice compartment temperature sensor (not shown) that detects the temperature of the water (ice) in the ice tray.

Although not shown, a control board (control unit) having a CPU, memories such as ROM and RAM, an interface circuit, etc. is arranged on the top of the refrigerator 1. The control board is connected by electrical wiring (not shown) to an outside air temperature sensor 37, an outside air humidity sensor 38, a refrigerator compartment temperature sensor 41, a freezer compartment temperature sensor 43, a vegetable compartment temperature sensor 44, an evaporator temperature sensor 40, a cooling plate temperature sensor 201, a door sensor, an ice compartment temperature sensor, etc.

An operation unit 18 is provided on the wall inside the refrigerator compartment 2. It can be used to adjust the temperature of the refrigerator compartment 2, freezer compartment 7, and vegetable compartment 6, and to give instructions to implement additional functions, such as a quick-cooling function that increases the cooling capacity of the refrigerator compartment 2.

The control board also controls the compressor 24, evaporator fan 9a, refrigerator compartment fan 9b, refrigerator compartment first damper 151, refrigerator compartment second damper 152, vegetable compartment damper 160, etc., based on the output values of each sensor, the settings of the operation unit 18, programs pre-recorded in the ROM, etc. The vegetable compartment damper 160 is also a cold air blocking means.

Figure 3 is an exploded perspective view showing the first refrigerator compartment air duct 110 and the second refrigerator compartment air duct 120 of Figure 2.

As shown in FIG. 3, the first refrigerator air passage 110 is formed inside a box-shaped member having a substantially rectangular parallelepiped shape. The second refrigerator air passage 120 is formed inside a box-shaped member having a substantially rectangular parallelepiped shape. A cooling plate 200 is sandwiched between the two box-shaped members. This separates the first refrigerator air passage 110 from the second refrigerator air passage 120, blocking air flow. A cooling plate auxiliary heater 202, which is a plate-type electric heater, is provided on the front surface of the cooling plate 200. The open surface of the box-shaped member of the first refrigerator air passage 110 is located on the side facing the cooling plate auxiliary heater 202. In other words, the rear side of the first refrigerator air passage 110 is closed by the cooling plate 200 having the cooling plate auxiliary heater 202.

A cooling plate temperature sensor 201 that detects the temperature of the cooling plate 200 is provided on the upper front surface of the cooling plate 200. The cooling plate auxiliary heater 202 consumes less power than the defrost heater 21. In this example, the maximum power (power consumption when energized at 100% duty) is 30 W, which is 1/5 of the power of the defrost heater 21.

Refrigerator compartment outlets 111a and 111b are provided at the top of the front surface of the first refrigerator compartment air passage 110 (the refrigerator compartment 2 side in FIG. 2). In addition, a first refrigerator compartment return port 115 is provided below the front surface of the first refrigerator compartment air passage 110. A refrigerator compartment fan 9b is provided behind the first refrigerator compartment return port 115.

A partition member 121 is provided vertically inside the second refrigerator compartment air passage 120. As a result, when the second refrigerator compartment damper 152 is opened, the cold air flows upward through the left air passage 120a of the second refrigerator compartment air passage 120, turns around at the top of the second refrigerator compartment air passage 120, and flows downward through the right air passage 120b of the second refrigerator compartment air passage 120, as shown by the arrows in the figure.

In the example shown in this figure, the material of the cooling plate 200 is an aluminum alloy. Since aluminum alloy has a high thermal conductivity, by using this, it is easier to transfer the cold heat on the side of the second air duct 120 of the refrigerator compartment to the air of the first air duct 110 of the refrigerator compartment. The material of the cooling plate 200 is not limited. The cooling plate 200 may be made of a resin such as polypropylene. Polypropylene and the like contribute to reducing costs. However, when using a resin member with a lower thermal conductivity than aluminum alloy, it is desirable to increase the amount of heat exchanged by devising the shape, for example by providing fins or dimples, in order to ensure the cooling capacity of the cooling plate 200. The shape of the cooling plate 200 may be any shape that seals the front of the second air duct 120 of the refrigerator compartment.

Figure 4 is a diagram showing the refrigeration cycle of the refrigerator in this embodiment.

In this figure, the compressor 24, the external radiator 50a, the wall surface heat radiation pipes 50b arranged on both sides of the heat-insulating box 10 (Fig. 2), the condensation prevention pipes 50c for preventing condensation on the outer surface of the outer box 10a (Fig. 2), the capillary tube 53 which is a pressure reducing means (pressure reducing section) for reducing the pressure of the refrigerant, and the evaporator 14 which absorbs heat inside the box by exchanging heat between the refrigerant and the air inside the box are connected in a ring shape by the refrigerant pipes to form a refrigeration cycle. The wall surface heat radiation pipes 50b are located in the area between the outer box 10a and the inner box 10b, and are located on the inner surface of the outer box 10a. The condensation prevention pipes 50c are located on the front side of the heat-insulating partition walls 27, 28, 29, and 30. The external radiator 50a, the wall surface heat radiation pipes 50b, and the condensation prevention pipes 50c are heat radiation means (radiators) that radiate heat from the refrigerant.

Between the condensation prevention pipe 50c and the capillary tube 53, a dryer 51 is provided to remove moisture mixed in the refrigerant circulating in the refrigeration cycle. Between the evaporator 14 and the compressor 24, a gas-liquid separator 54 is provided to suppress the inflow of liquid refrigerant into the compressor 24. A portion of the refrigerant pipe connecting the evaporator 14 and the compressor 24 is in contact with the capillary tube 53 and forms a heat exchange section 57.

In the refrigeration cycle shown in this figure, when the compressor 24 is driven, the refrigerant is compressed, and the high-temperature, high-pressure gas refrigerant dissipates heat while flowing through the external radiator 50a, the wall surface heat dissipation pipe 50b, and the condensation prevention pipe 50c, and becomes liquid refrigerant. After this refrigerant flows through the dryer 51 to remove moisture, it is decompressed in the capillary tube 53, and becomes a low-temperature, low-pressure two-phase refrigerant that reaches the inlet of the evaporator 14.

The air returned from each storage chamber in the cabinet by the operation of the evaporator fan 9a (Figure 2) passes through the evaporator 14, where it exchanges heat with the low-temperature refrigerant in the evaporator 14, becoming colder, and cooling each storage chamber in the cabinet again. At this time, the refrigerant absorbs heat from the air in the cabinet, increasing its enthalpy and its dryness, and it becomes a nearly saturated gas refrigerant and reaches the outlet of the evaporator 14.

A portion of the piping that returns from the outlet of the evaporator 14 to the compressor 24 is provided in close proximity to the capillary tube 53 so as to exchange heat with it. As a result, it is heated by the refrigerant in the capillary tube 53, causing the enthalpy to increase (the temperature rises), and it is sucked back into the compressor 24. By providing the heat exchange section 57 in this way, the temperature of the refrigerant sucked into the compressor 24 increases, preventing condensation and frost on the refrigerant piping, and the enthalpy of the refrigerant flowing into the evaporator 14 is reduced by the heat exchange, improving the cooling capacity of the evaporator.

In the example shown in this diagram, the refrigerant used in the refrigeration cycle is isobutane, a flammable refrigerant.

Next, we will explain the air duct configuration of the refrigerator in this embodiment.

Figure 5 is a schematic diagram showing the air duct configuration of a refrigerator according to an embodiment.

In this diagram, from the top, the refrigerator compartment 2, ice-making compartment 3, upper freezer compartment 4, lower freezer compartment 5, and vegetable compartment 6 are shown. Also shown is the evaporator fan 9a that circulates the cold air that has exchanged heat with the evaporator 14 in the evaporator compartment 8.

The cold air sent out from the evaporator fan 9a passes through the freezer compartment air duct 100 and flows into the ice making compartment 3, upper freezer compartment 4, and lower freezer compartment 5 from the ice making compartment outlet 101, upper freezer compartment outlet 102, and lower freezer compartment outlet 103, respectively, regardless of the open/closed state of the refrigerator compartment first damper 151, refrigerator compartment second damper 152, and vegetable compartment damper 160. The cold air that has cooled the ice making compartment 3, upper freezer compartment 4, and lower freezer compartment 5 returns to the evaporator chamber 8 from the lower freezer compartment 5 through the freezer compartment return air duct 105.

When the vegetable compartment damper 160 is open, the cold air sent out from the evaporator fan 9a flows through the vegetable compartment air duct 130 that branches off downstream of the freezer compartment air duct 100, and enters the vegetable compartment 6 from the vegetable compartment outlet 131. In the vegetable compartment 6, the cold air flows along the outer surface of the vegetable compartment container 6b, preventing the drying of foods such as vegetables stored in the vegetable compartment container 6b and preventing excessive temperature drops. The cold air that has cooled the vegetable compartment 6 passes through the vegetable compartment return port 136, enters the vegetable compartment return air duct 135, and returns to the evaporator chamber 8.

When the refrigerator compartment first damper 151 is opened, the cold air sent out from the evaporator fan 9a flows into the refrigerator compartment first air duct 110 and into the refrigerator compartment 2 from the refrigerator compartment outlet 111, cooling the refrigerator compartment 2. The cold air that has cooled the refrigerator compartment 2 flows through the refrigerator compartment return outlet 126 and the refrigerator compartment return air duct 125, and returns to the evaporator chamber 8. Hereinafter, this operating mode in which the refrigerator compartment first damper 151 is opened to cool the refrigerator compartment 2 is referred to as "direct cooling operation."

When the second refrigerator damper 152 is opened, the cold air sent out from the evaporator fan 9a flows into the second refrigerator air duct 120, exchanges heat with the air in the first refrigerator air duct 110 via the cooling plate 200, and then flows through the refrigerator return air duct 125 and returns to the evaporator chamber 8.

In this case, when the refrigerator compartment fan 9b is driven with the refrigerator compartment first damper 151 closed, the air in the refrigerator compartment 2 enters the refrigerator compartment first air duct 110 from the refrigerator compartment first return port 115, flows through the refrigerator compartment first air duct 110, and enters the refrigerator compartment 2 from the refrigerator compartment outlet port 111. In other words, an air flow circulating within the refrigerator compartment 2 is formed.

Therefore, when the first refrigerator compartment damper 151 is closed, the second refrigerator compartment damper 152 is opened, and the evaporator fan 9a and the refrigerator compartment fan 9b are driven, the cold air sent out from the evaporator fan 9a and flowing into the second refrigerator compartment air duct 120 cools the air in the first refrigerator compartment air duct 110 via the cooling plate 200, and the air in the first refrigerator compartment air duct 110, which has become cold as a result, is sent into the refrigerator compartment 2. This allows the inside of the refrigerator compartment 2, which is a closed space, to be cooled. Hereinafter, this operating method of cooling the refrigerator compartment 2 with the first refrigerator compartment damper 151 closed and the second refrigerator compartment damper 152 open is referred to as "indirect cooling operation."

As described above, the definitions of "direct cooling operation" and "indirect cooling operation" in this specification differ from those in Patent Documents 2 and 3.

Figure 6A is a front view showing the direct cooling operation of the refrigerator. Note that in this figure, doors 2a, 2b, 3a, 4a, 5a, and 6a and containers 3b, 4b, 5b, and 6b are omitted.

In this diagram, the first refrigerator damper 151 is open and the second refrigerator damper 152 is closed, so the cold air pressurized by the evaporator fan 9a is sent to the ice-making compartment 3, the upper freezer compartment 4, and the lower freezer compartment 5, and also passes through the first refrigerator air duct 110 and flows into the refrigerator compartment 2 from the refrigerator air outlet 111, cooling the refrigerator compartment 2. The cold air that has cooled the refrigerator compartment 2 flows through the refrigerator compartment return port 126 and the refrigerator compartment return air duct 125, returning to the evaporator chamber 8 (Figure 5).

Since the refrigerator compartment fan 9b is disposed in the first refrigerator compartment air duct 110, when the refrigerator compartment fan 9b is driven with the first refrigerator compartment damper 151 open, the cold air is pressurized by the refrigerator compartment fan 9b, and the amount of cold air from the evaporator 14 flowing into the first refrigerator compartment air duct 110 can be increased.

Figure 6B is a front view showing the indirect cooling operation of the refrigerator. Note that in this figure, doors 2a, 2b, 3a, 4a, 5a, and 6a and containers 3b, 4b, 5b, and 6b are omitted.

In this diagram, the first refrigerator damper 151 is closed and the second refrigerator damper 152 is open, so the cold air pressurized by the evaporator fan 9a is sent to the ice-making compartment 3, the upper freezer compartment 4, and the lower freezer compartment 5, and also flows through the second refrigerator air duct 120. The cold air in the second refrigerator air duct 120 exchanges heat with the air in the first refrigerator air duct 110 via the cooling plate 200, then flows through the return refrigerator air duct 125 and returns to the evaporator chamber 8 (Figure 5).

Although details will be described later, during indirect cooling operation, cooling is performed at a temperature lower than the frost point temperature _Tfp of the refrigerator compartment 2 (a temperature lower than the dew point temperature of the refrigerator compartment 2 and equal to or lower than the melting point of 0° C.), and frost forms on the surface of the cooling plate 200 on the side of the first air duct 110 of the refrigerator compartment.

Here, we compare the two cooling operations of the refrigerator compartment 2 mentioned above, namely direct cooling operation and indirect cooling operation.

In direct cooling operation, the refrigerator compartment 2 is cooled with low-temperature cold air from the evaporator 14, making it easy to ensure cooling capacity, but the air that has been made low-humidity by the evaporator 14, which is basically controlled to a low temperature of -20°C or lower in order to cool the freezer compartment 7 in the freezing temperature range, reaches the refrigerator compartment 2. In addition, since the air in the refrigerator compartment 2 is dehumidified by the evaporator 14, the moisture content in the refrigerator compartment 2 is likely to decrease.

On the other hand, in indirect cooling operation, cooling is performed via the cooling plate 200, so the air in the refrigerator compartment 2 is not sent to the low-temperature evaporator 14 to be dehumidified. In indirect cooling operation, the air in the refrigerator compartment 2 frosts on the cooling plate 200, but the cooling plate 200 is cooled by the air flowing through the refrigerator compartment second air duct 120 sent from the evaporator 14, so it becomes hotter than the evaporator 14. This makes it possible to suppress a decrease in the amount of moisture in the refrigerator compartment 2. This makes it easier to maintain a high relative humidity in the refrigerator compartment 2.

In general, in heat exchange between a wall surface (heat exchange surface) and air, if the absolute humidity of the air is X _air and the absolute humidity in the saturated state at the temperature of the wall surface (saturated absolute humidity of the wall surface) is X _wall , the larger the absolute humidity difference (X _air - X _wall ) is, the larger the amount of mass transfer to the wall surface will be. Also, the lower the wall surface temperature that is exchanged with heat (the surface temperature of the evaporator 14 in this case), the lower X _wall will be.

For example, when the air in the refrigerator compartment 2 has a temperature of 2° C. and a relative humidity of 80%, X _air is 3.5×10 ⁻³ kg/kg (DA), and when the wall temperature is −20° C., X _wall is 0.6×10 ⁻³ kg/kg (DA). Therefore, X _air −X _wall is 2.9×10 ⁻³ kg/kg (DA).

In contrast, when the wall temperature is −5° C., X _wall is 2.5×10 ⁻³ kg/kg (DA), and X _air −X _wall is 1.0×10 ⁻³ kg/kg (DA). In this case, X _air −X _wall is smaller than when the wall temperature is −20° C., and the dehumidification amount is smaller.

When X _air −X _wall is a negative value, ie, X _wall >X _air , if there is moisture on the wall surface, the moisture evaporates and the amount of moisture in the air (absolute humidity) increases.

In addition to the above operations, there is a first circulation operation, which is a defrosting operation of the cooling plate 200.

Figure 7 is a front view showing the air flow during the first circulation operation of the refrigerator according to the embodiment.

As shown in this figure, in the first circulation operation, both the first refrigerator damper 151 and the second refrigerator damper 152 are closed, and the refrigerator fan 9b is driven. Because the second refrigerator damper 152 is closed, air from the evaporator 14 does not flow into the second refrigerator air duct 120, and cooling of the cooling plate 200 is stopped. In addition, because the first refrigerator damper 151 is closed, the air flowing into the first refrigerator air duct 110 is air from the refrigerator chamber 2.

Since frost is basically below the melting point of ice, i.e., below 0°C, when frost is present on the cooling plate 200, air from the refrigerator compartment 2 (above 0°C) flows into the first refrigerator compartment air duct 110, causing heat exchange between the cooling plate 200 and the frost on the cooling plate 200 and the air from the refrigerator compartment 2. This allows the refrigerator compartment 2 to be cooled and the cooling plate 200 to be defrosted.

The defrost heater 21 (Fig. 2) in the evaporator chamber 8 that melts the frost on the evaporator 14 consumes power of about 150 W, but the power consumed in the first circulation operation that melts the frost on the cooling plate 200 is only the power to drive the refrigerator compartment fan 9b (basically 3 W or less). Furthermore, there is an additional effect that the refrigerator compartment 2 can be cooled by heat exchange between the cooling plate 200 (including frost) and the air in the refrigerator compartment 2, so by defrosting the cooling plate 200 in the first circulation operation, energy saving performance can be improved compared to defrosting using an electric heater such as the defrost heater 21 (Fig. 2).

During this first circulation defrosting, mass transfer also occurs between the frost adhering to the cooling plate 200 and the air in the refrigerator compartment 2 flowing into the refrigerator compartment first air duct 110. This mass transfer can humidify the air in the refrigerator compartment 2, as will be described in detail later.

The first circulation operation shown in FIG. 7 can be performed even when the compressor 24 is stopped and the freezer compartment 7 is not being cooled. In this case, if the evaporator fan 9a is stopped, the flow of air from the evaporator 14 to the refrigerator compartment second air duct 120 is suppressed even if the refrigerator compartment second damper 152 is open, so the first circulation operation is performed.

Next, the cooling operation control of the refrigerator according to this embodiment will be explained using a temperature chart and a flow chart.

8 is a graph showing an example of temperature changes during cooling operation of the refrigerator according to the embodiment. The horizontal axis indicates time, and the vertical axis indicates the temperature of each part and the operating state of each part. The temperature changes are shown for the vegetable compartment, the refrigerator compartment, the cooling surface (cooling plate), the freezer compartment, and the evaporator. In addition, values corresponding to these temperatures are shown as the reference lower limit temperature T _{V_off} of the vegetable compartment, the defrost reference temperature T _{DR_off} of the cooling plate, the set temperature T _{R_off} of the refrigerator compartment, the reference upper limit temperature T _{F_start} of the freezer compartment, and the reference lower limit temperature T _{F_off} of the freezer compartment.

On the horizontal axis of this figure, _t0 indicates the start time of the cooling operation, _t1 indicates the time when the vegetable compartment damper 160 is closed, _t2 indicates the time when the refrigerator compartment fan 9b is stopped and the refrigerator compartment second damper 152 is closed, _t3 indicates the time when the compressor 24 and the evaporator fan 9a are stopped, _t4 indicates the time when the compressor 24, the evaporator fan 9a, and the refrigerator compartment fan 9b are driven and the refrigerator compartment second damper 152 and the vegetable compartment damper 160 are opened, _t5 indicates the time when the vegetable compartment damper 160 is closed, _t6 indicates the time when the refrigerator compartment second damper 152 is closed, _t7 indicates the time when the compressor 24 and the evaporator fan 9a are stopped, _t8 indicates the time when the refrigerator compartment fan 9b is stopped, and _t9 indicates the time when the compressor 24, the evaporator fan 9a, and the refrigerator compartment fan 9b are driven and the refrigerator compartment second damper 152 and the vegetable compartment damper 160 are opened.

Note that during the cooling operation shown in this figure, the first refrigerator compartment damper 151 is closed.

Figure 9 is a flowchart showing the basic control of the cooling operation of a refrigerator in accordance with an embodiment.

As shown in the figure, it is determined whether the freezing compartment temperature T _F detected by the freezing compartment temperature sensor 43 is equal to or higher than a reference upper limit temperature T _{F_start} (for example, equal to or higher than -18°C) (time t ₀ , step S-1). If _{T F} ≧T _{F_start} , the compressor 24 and the evaporator fan 9a are driven to start the cooling operation (step S-2).

Thereafter, it is determined whether the freezer compartment temperature T _F is equal to or lower than the reference lower limit temperature T _{F_off} (for example, equal to or lower than -22°C) (time t ₃ , step S-3). If T _F ≦T _{F_off} , the compressor 24 and the evaporator fan 9a are stopped (step S-4). Then, returning to step S-1, if T _F ≧T _{F_start} again, the compressor 24 and the evaporator fan 9a are driven to perform a cooling operation (time t ₄ ), and the cooling operation is continued until T _F ≦T _{F_off} (time t ₇ ). Basically, the cooling operation control is performed according to this flow.

During this time, cooling control is performed for the refrigerator compartment 2 and vegetable compartment 6.

First, we will explain the cooling control of the vegetable compartment 6.

When the cooling operation is started, the vegetable compartment control is also started, the vegetable compartment damper 160 is opened (step S-V1), and the cooling of the vegetable compartment 6 is started (time _t0 ). Then, it is determined whether the vegetable compartment temperature _TV detected by the vegetable compartment temperature sensor 44 has reached the reference lower limit temperature _{TV_off} (step S-V2). If _TV ≦ _{TV_off} , the vegetable compartment damper 160 is closed to prevent the vegetable compartment 6 from becoming too cold, and the cooling of the vegetable compartment 6 is stopped (step S-V3, time _t1 ).

Even if the compressor 24 is stopped by step S-4, the answer is Yes in step S-V2, the vegetable compartment damper 160 is closed, and cooling of the vegetable compartment 6 is stopped (step S-V3).

Furthermore, if the vegetable compartment temperature _TV becomes equal to or higher than a predetermined temperature _{TV_restart} during cooling operation (when the compressor 24 is not stopped) (Yes in step S-V4), the vegetable compartment damper 160 is opened again and cooling operation of the vegetable compartment 6 is performed (step S-V1) in order to maintain the temperature of the vegetable compartment 6 within a predetermined range.

Next, we will explain the cooling control of the refrigerator compartment 2.

When the cooling operation is started (time t ₀ ), the refrigerator compartment control is also started.

First, in order to ensure that the defrosting of the cooling plate 200 is completed, it is necessary to prevent the cooling operation from starting during the first circulation operation or the second circulation operation described later. Therefore, it is determined whether the first circulation operation and the second circulation operation have ended (step S-R1). If the first circulation operation and the second circulation operation have ended (Yes in step S-R1), it is next determined whether the refrigerator compartment temperature _TR detected by the refrigerator compartment temperature sensor 41 is equal to or higher than a predetermined temperature _{TR_high} (for example, equal to or higher than 5°C) (step S-R2).

The graph shown in FIG. 8 shows a case where the refrigerator compartment T _R is less than T _{R_high} (step S-R2 is No at time t ₀ ). In this case, the refrigerator compartment fan 9b is driven, the refrigerator compartment first damper 151 is closed, and the refrigerator compartment second damper 152 is opened (step S-R3), and the refrigerator compartment 2 is cooled by indirect cooling operation (FIG. 6B) which tends to keep the relative humidity in the refrigerator compartment 2 high. This prevents food deterioration in the refrigerator compartment 2 by keeping it at a low temperature, and also prevents food deterioration in the refrigerator compartment 2 due to drying. During this time, the refrigerator compartment 2 becomes highly humid (high absolute humidity), and the cooling plate 200 becomes low temperature (saturation absolute humidity of the wall surface is low) to cool the refrigerator compartment 2, so that mass transfer (adhesion of moisture) occurs from the air in the refrigerator compartment 2 to the cooling plate 200. 8, since the cooling plate 200 is basically below 0° C. during cooling (time t ₀ to t ₂ ), frost forms on the cooling plate 200. Note that, although details will be described later, in this embodiment, frost is intentionally formed on the cooling plate 200 in order to suppress frost formation on the heat insulating partition wall 27, etc. The control for this will be described with reference to FIG.

In the graph shown in Fig. 8, although this is not performed because the conditions are not satisfied, when the refrigerator compartment T _R becomes equal to or higher than T _{R_high} (Yes in step S-R2), it is necessary to give priority to lowering the temperature of the refrigerator compartment 2. In this case, the refrigerator compartment fan 9b is driven, the first refrigerator compartment damper 151 is opened, and the second refrigerator compartment damper 152 is closed (step S-R3), and the refrigerator compartment 2 is cooled by direct cooling operation (Fig. 6A) in which low-temperature air from the evaporator 14 is blown into the refrigerator compartment 2. This eliminates the high-temperature state of the refrigerator compartment 2 in a short time, and deterioration of food in the refrigerator compartment 2 due to high temperatures can be suppressed.

If the compressor 24 is not stopped midway (step S-R4 is No), a judgment is made in step S-R2 as appropriate, and if the refrigerator compartment temperature T _R becomes lower than the predetermined temperature T _{R_high} (step S-R2 is No), the operation transitions to indirect cooling operation.

Then, the refrigerator compartment 2 is cooled by the indirect cooling operation, and when the compressor 24 stops or the refrigerator compartment temperature _TR reaches the predetermined temperature _{TR_off} (time _t2 , step S-R6 is Yes), the refrigerator compartment second damper 152 is closed (step S-R7) to prevent the refrigerator compartment 2 from being overcooled, and the cooling of the refrigerator compartment 2 is terminated. Note that even after the first circulation operation is terminated (steps S-R8 to S-R13), the compressor 24 is still driven, and when the refrigerator compartment temperature _TR becomes higher than the predetermined temperature _{TR_restart} (step S-R14 is Yes), the refrigerator compartment 2 is cooled again (steps S-R2 to S-R7) to maintain the temperature of the refrigerator compartment 2 within the predetermined range.

After cooling of the refrigerator compartment 2 is completed, the first circulation operation is performed. Note that defrosting is not required every time, and the first circulation operation is performed once every N times (steps S-R8 to S-R10). In the example of Fig. 8, N is 2, and the first circulation operation is omitted at time _t2 because the count is 1, and the first circulation operation is started at time _t6 because the count is 2.

In the first circulation operation, the refrigerator compartment fan 9b is driven (step S-R11) while both the refrigerator compartment first damper 151 and the refrigerator compartment second damper 152 are closed (step S-R7).

After the cooling plate temperature T _DR detected by the cooling plate temperature sensor 201 reaches a predetermined temperature T _{DR_off} or higher (e.g., 2°C or higher) that is higher than the frost melting temperature of 0°C (time t ₈ , step S-R12 is Yes), the refrigerator compartment fan 9b is stopped (step S-R13), and the first circulation operation is terminated.

The details and effects of the above-mentioned cooling operation control are explained further below.

First, in the refrigerator of this embodiment, as shown in Fig. 8 and Fig. 9, the refrigerator compartment 2 is basically configured for indirect cooling operation, i.e., cooling via the cooling plate 200. During indirect cooling operation, frost forms on the cooling plate 200. The reason for this will be explained.

As explained using Figures 6A and 6B, cooling the refrigerator compartment 2 by indirect cooling operation can keep the refrigerator compartment 2 at a higher humidity than cooling the refrigerator compartment 2 by direct cooling operation. Therefore, for example, when the surrounding temperature is abnormally high or when there is no external load such as opening and closing the door or putting food in, it is desirable to cool the refrigerator compartment 2 by indirect cooling operation. For this reason, the cooling plate 200 is designed to ensure a cooling capacity that can sufficiently cool the refrigerator compartment 2 in indirect cooling operation.

In addition, as will be described in detail later, in order to ensure the time for the first circulation operation, which is effective in maintaining an even higher humidity inside the refrigerator compartment 2, that is, to ensure the time when the cooling operation is not performed, a high cooling capacity is required for the indirect cooling operation. When cooling the refrigerator compartment 2 by the indirect cooling operation, heat is exchanged between the air flowing through the refrigerator compartment first air duct 110 and the cooling plate 200.

In addition, because the air in the first refrigerator compartment air duct 110 is the return air of the refrigerator compartment 2, the temperature and humidity of the air immediately after it enters the first refrigerator compartment air duct 110 (near the first refrigerator compartment return port 115) are essentially the same as those in the refrigerator compartment 2. In a high humidity refrigerator compartment 2, for example, when the refrigerator compartment 2 is at 2°C and the relative humidity is 80%, and the dew point temperature (frost point temperature) is -1.0°C, that is, when a temperature difference of 3.0°C or more occurs, heat exchange and mass transfer of moisture (condensation or frost) from the air in the first refrigerator compartment air duct 110 to the wall surface occurs. Here, the amount of heat exchanged between the cooling plate 200 and the air in the first air duct 110 of the refrigerator compartment is determined by the mass flow rate of the air in the first air duct 110 of the refrigerator compartment exchanging heat with the cooling plate 200, the heat transfer coefficient between the cooling plate 200 and the air in the first air duct 110 of the refrigerator compartment, the area of the cooling plate 200, and the temperature difference between the surface temperature of the cooling plate 200 on the side of the first air duct 110 of the refrigerator compartment and the air temperature in the first air duct 110 of the refrigerator compartment.

Therefore, in order to obtain a cooling capacity (high heat exchange amount) that allows the cooling plate 200 to sufficiently cool the refrigerator compartment 2 during indirect cooling operation, it is necessary to ensure a temperature difference between the surface temperature of the cooling plate 200 on the refrigerator compartment first air duct 110 side and the air temperature in the refrigerator compartment first air duct 110. In other words, in order to ensure the necessary cooling capacity while keeping the humidity in the refrigerator compartment 2 high, it is necessary to lower the temperature of the cooling plate 200 so that mass transfer (condensation or frost) occurs from the refrigerator compartment first air duct 110 to the surface of the cooling plate 200 on the refrigerator compartment first air duct 110 side.

The target temperature for the refrigerator compartment for calculating the power consumption described in, for example, JIS C9801-3:2015 and IEC 62552-3:2015 is 4°C, and the average temperature of the refrigerator compartment 2 in this embodiment is controlled to an even lower temperature of approximately 2°C, which is close to the melting point temperature of 0°C. Therefore, if a temperature difference between the cooling plate 200 and the air is ensured in order to obtain a high amount of heat exchange, the surface temperature of the cooling plate 200 on the side of the first air duct 110 of the refrigerator compartment will be below 0°C, and the moisture that has migrated to the cooling plate 200 will adhere as frost to the surface on the side of the first air duct 110 of the refrigerator compartment.

As described above, the refrigerator 1 of the first embodiment is provided with the first refrigerator compartment air duct 110 that exchanges heat with the cooling plate 200, and the surface temperature of the cooling plate 200 on the first refrigerator compartment air duct 110 side is lowered to a temperature range where frost forms on the surface of the cooling plate 200 on the first refrigerator compartment air duct 110 side, i.e., a temperature lower than the frost point temperature. This ensures the cooling capacity required for indirect cooling operation, and achieves a high humidity refrigerator compartment.

It is also possible to provide a cooling plate 200 in the refrigerator compartment 2 without providing the first refrigerator compartment air duct 110 (exposing the cooling plate 200 in the refrigerator compartment 2), thereby directly cooling the air in the refrigerator compartment 2 with the cooling plate 200.

However, in this case, the frost may come into contact with the stored items (food, etc.) in the refrigerator compartment 2, or the stored items may come into direct contact with the cooling plate 200, which is below the frost point temperature, which may cause unintended freezing or deterioration of the stored items, such as low-temperature damage.

In addition, if the first refrigerator compartment air duct 110 is not provided, the air in the refrigerator compartment 2 does not actively flow near the cooling plate 200 (flow speed is low), and the heat transfer coefficient between the cooling plate 200 and the air is low, which causes the problem that it is difficult to ensure the necessary cooling capacity (amount of heat exchanged). Furthermore, if the heat transfer coefficient is low, the mass transfer coefficient also becomes low, making humidification (mass transfer) during the first circulation operation described below difficult.

In contrast, in the refrigerator 1 of this embodiment, the first refrigeration chamber air duct 110 that exchanges heat with the cooling plate 200 is provided, thereby suppressing contact between the frosted surface of the cooling plate 200 and the cooling plate 200, which is kept at a low temperature below the frost point temperature, and food. In addition, by allowing the air in the refrigerator chamber 2 to flow through the first refrigeration chamber air duct 110, the air flow is concentrated near the cooling plate 200, improving the heat transfer coefficient with the cooling plate 200 and improving the heat exchange performance. In other words, in order to cause frost to form on the cooling plate 200 (to cool the cooling plate 200 to a temperature lower than the frost point temperature) and ensure the cooling capacity required for indirect cooling operation, it is desirable to provide the first refrigeration chamber air duct 110, which is an air duct for exchanging heat between the air in the refrigerator chamber 2 and the cooling plate 200.

Next, we will explain why the first circulation operation is performed by closing both the first refrigerator compartment damper 151 and the second refrigerator compartment damper 152 and driving the refrigerator compartment fan 9b.

The first reason is to suppress frost growth, as in the defrosting operation of the evaporator 14. As mentioned above, in the refrigerator 1 of this embodiment, frost is formed on the surface of the cooling plate 200. If the frost growth due to this frost progresses excessively, the first air duct 110 of the refrigerator compartment will be blocked and the thermal resistance between the cooling plate 200 and the air will increase, resulting in a decrease in heat exchange performance. In other words, if frost growth continues, it will become difficult to ensure the necessary cooling capacity, so the first circulation operation is performed as a defrosting operation to suppress this.

The second reason is that moisture adhering to the cooling plate 200 due to frosting is returned to the refrigerator compartment 2. When frost forms on the cooling plate 200 during indirect cooling operation, the moisture in the refrigerator compartment 2 decreases, but this moisture can be returned to the refrigerator compartment 2 by performing the first circulation operation. In the first circulation operation, as described above with reference to FIG. 7 and the like, both the refrigerator compartment first damper 151 and the refrigerator compartment second damper 152 are closed, the refrigerator compartment fan 9b is driven, and air is circulated between the refrigerator compartment 2 and the cooling plate 200 via the refrigerator compartment first air duct 110. At this time, the cooling plate 200 exchanges heat with the air in the refrigerator compartment 2 in an uncooled state, so the temperature difference between the refrigerator compartment 2 and the cooling plate 200 is small, and the refrigerator compartment 2 is dehumidified by the indirect cooling operation, so that the temperature of the cooling plate 200 may become higher than the dew point temperature of the refrigerator compartment 2. When the temperature of the cooling plate 200 becomes higher than the dew point temperature, the saturated absolute humidity X _wall of the wall surface becomes higher than the absolute humidity X _air of the air (X _wall >X _air ), and when there is frost on the wall surface, the moisture of the frost is transferred to the air (evaporated) and the air can be humidified. That is, by performing the first circulation operation, it is possible to suppress the growth of frost (to perform defrosting) and to increase the humidity in the refrigerator compartment 2.

Here, the first air duct 110 is provided, and the air from the refrigerator compartment 2 is actively introduced into the first air duct 110 by driving the refrigerator compartment fan 9b during the first circulation operation, thereby increasing the heat transfer coefficient and mass transfer coefficient between the cooling plate 200 and the air in the first air duct 110. Increasing the heat transfer coefficient between the cooling plate 200 and the air in the first air duct 110 increases the amount of heat exchanged. In addition, increasing the mass transfer coefficient between the cooling plate 200 and the air in the first air duct 110 increases the amount of mass transferred per hour. In other words, the amount of heat exchanged for defrosting and the amount of mass transferred per hour for humidification are increased, ensuring the aforementioned effects (suppression of frost growth and high humidity in the refrigerator compartment 2).

As a result, the refrigerator 1 of this embodiment has the following features and effects.

First, by performing indirect cooling operation using the cooling plate 200 at a higher temperature than the evaporator 14, the decrease in absolute humidity (moisture content) in the refrigerator compartment 2 is suppressed compared to direct cooling operation. Then, in indirect cooling operation, frost forms in order to cool the refrigerator compartment 2, but by performing a first circulation operation in which air is circulated between the refrigerator compartment 2 and the cooling plate 200, mass transfer occurs from the frost on the cooling plate 200 to the air in the refrigerator compartment 2, increasing the absolute humidity. In other words, a refrigerator with a high humidity refrigerator compartment can be provided.

As a method for suppressing the growth of frost on the cooling plate 200 (defrosting method), for example, a method of melting the frost on the cooling plate 200 by natural convection without circulating air (forced convection) between the refrigerator compartment 2 and the cooling plate 200 by the refrigerator compartment fan 9b, or a method of melting the frost by heating with an electric heater similar to the defrosting operation of the evaporator 14 can be considered. However, if air is not circulated between the refrigerator compartment 2 and the cooling plate 200 (more precisely, when circulation is by natural convection only), there is almost no transfer of moisture from the cooling plate 200 to the air, and the frost attached to the cooling plate 200 hardly humidifies the refrigerator compartment 2, making it difficult to achieve a high humidity refrigerator compartment.

In addition, if frost is melted using natural convection alone, without using an electric heater, it takes time to melt the frost, and time cannot be secured for indirect cooling operation of the refrigerator compartment 2. Instead, direct cooling operation, which can cool in a short time, is required, which also makes it difficult to maintain a high humidity level inside the refrigerator compartment 2.

On the other hand, even when an electric heater is used, the amount of power consumed during defrosting operation is an issue, making it difficult to perform the operation frequently.

As described above with reference to FIG. 7, the defrosting method of this embodiment can reduce power loss and has higher energy-saving performance than the method using an electric heater. The first circulation operation is performed about 10 times a day, but the defrosting operation of the evaporator 14 is performed about once a day because it has a large impact on energy-saving performance. In other words, with the electric heater method, the humidifying effect of the first circulation operation is small, and furthermore, the first circulation operation for humidifying the refrigerator compartment 2 can only be performed infrequently, making it difficult to achieve a refrigerator compartment with a high humidity.

As described above, even if frost is formed on the cooling plate 200 to ensure the cooling capacity required for the indirect cooling operation described above, excessive frost growth can be suppressed by performing the first circulation operation in which air is circulated between the refrigerator chamber 2 and the cooling plate 200 by the refrigerator chamber fan 9b while suppressing the cooling of the cooling plate 200 (a state in which the refrigerator chamber second damper 152 is closed and air blowing to the refrigerator chamber second air duct 120 is suppressed). In addition, the moisture that has moved to the cooling plate 200 due to frost formation can be returned to the refrigerator chamber 2. Thus, a refrigerator chamber 2 with a high humidity can be more reliably achieved.

In this embodiment, the first circulation operation is performed until the cooling plate temperature _TDR detected by the cooling plate temperature sensor 201 reaches a predetermined temperature _{TDR_off} or higher (e.g., 2°C or higher) that is higher than the frost melting temperature of 0°C. However, the humidifying effect of the first circulation operation is the main purpose, and it is not necessary to melt the frost on the cooling plate 200. In this case, however, it is necessary to provide an operation for more reliable defrosting. This will be described later as the second circulation operation using Figures 11 and 12.

In addition to the second circulation operation which more reliably removes frost, the first circulation operation is also performed until the cooling plate temperature _TDR detected by the cooling plate temperature sensor 201 exceeds the melting point temperature, thereby suppressing frost growth over a long period of time.

In addition, since it is equipped with a second circulation operation that more reliably defrosts, even if the frost on the cooling plate 200 does not melt completely in the first circulation operation, the frost on the surface facing the air melts once and turns to water, and the water penetrates into the frost, increasing its density. In other words, it becomes closer to ice than to frost. This alone is effective in suppressing frost growth. The increased density reduces blockage of the first refrigerator compartment air duct 110 and thermal resistance caused by frost, reduces the effects of reduced cooling capacity caused by frost, and lengthens the period until the second defrost operation is required.

In the refrigerator 1 of this embodiment, the cooling plate 200 is cooled by air from the evaporator 14 via the second refrigerator compartment air duct 120, but the above-mentioned effects can also be obtained with the configurations of the following modified examples 1 and 2.

(Variation 1)
FIG. 10A is a configuration diagram showing a refrigeration cycle of the first modification.

In the explanation of Figure 10A, only the configuration that differs from Figure 4 will be explained.

In FIG. 10A, the refrigerant pipe 200p (shown by a dashed line) provided between the gas-liquid separator 54 and the heat exchanger 57 is configured to be in contact with the cooling plate 200. In other words, this modified example realizes indirect cooling operation by using a refrigeration cycle.

In this case, the cooling plate 200 is cooled by the low-temperature refrigerant flowing downstream of the evaporator 14, instead of the low-temperature air from the evaporator 14. In this case, the refrigerant used in the evaporator 14 is heated and gasified by the air in the evaporator chamber 8, so the air in the refrigerator compartment 2 can be cooled by the cooling plate 200, which has a higher wall temperature than the evaporator 14. Therefore, with the indirect cooling operation of this modified example, the decrease in absolute humidity in the refrigerator compartment 2 can be suppressed.

In addition, while the compressor 24 is stopped, cooling of the cooling plate 200 is suppressed, and during this time, the first circulation operation can be performed by driving the refrigerator compartment fan 9b to circulate air between the refrigerator compartment 2 and the cooling plate 200 while preventing air from flowing in from the evaporator 14.

In this modified example, the second refrigerator compartment air duct 120 for cooling the cooling plate 200 is not required, and the air duct configuration can be simplified.

On the other hand, in this modified example, since the temperature of the refrigerant pipe 200p depends on the state of the refrigerant flowing through the evaporator 14, it may be difficult to control the temperature of the cooling plate 200.

In this regard, in the configuration of the embodiment, the airflow to the second refrigerator compartment air duct 120 can be controlled by the second refrigerator compartment damper 152, so the temperature of the cooling plate 200 can be easily controlled. Also, in the configuration of the embodiment, a normal refrigeration cycle as shown in FIG. 4 can be used, and assembly work can be performed just like a normal refrigerator by simply using the air duct components shown in FIG. 3. Therefore, productivity can be improved when increasing the variety of refrigerators to be manufactured.

In addition, in this modified example, the first circulation operation is possible, but the cooling plate 200 is always cooled while the compressor 24 is running. Therefore, in this modified example, the first circulation operation can only be performed while the compressor 24 is stopped.

When a low-temperature freezer compartment 7 is provided in addition to the refrigerator compartment 2 as in the embodiment, as shown in Figures 8 and 9, even after cooling of the refrigerator compartment 2 is completed, the time during which the compressor 24 is driven to cool the freezer compartment 7 (the time during which the compressor 24 is not stopped) is relatively long.

For this reason, if the drive pattern of the compressor 24 in the embodiment is applied to this modified example, the time for the first circulation operation is limited only when the compressor 24 is stopped, and it is thought that the first circulation operation time cannot be sufficiently secured, which may result in problems such as insufficient humidification and frost growth.

To secure the defrosting time, it is possible to extend the time that the compressor 24 is stopped, but it is necessary to increase the cooling capacity during cooling operation, and the general method for doing so is to increase the rotation speed of the compressor 24. When the rotation speed of the compressor 24 is increased, the evaporation temperature decreases and the condensation temperature increases, and therefore the energy saving performance usually decreases.

In contrast, according to the configuration of the embodiment, the first circulation operation can be performed even while the freezer compartment 7 is being cooled (while the compressor 24 is operating).

(Variation 2)
FIG. 10B is a configuration diagram showing a refrigeration cycle of the second modification.

In explaining this diagram, we will only explain the configuration that differs from Figure 4.

In FIG. 10B, a three-way valve 300 is provided between the dryer 51 and the heat exchanger 57. In addition to the capillary tube 53, a second capillary tube 53b is provided in the heat exchanger 57. The three-way valve 300 is configured to switch the refrigerant through either the capillary tube 53 or the second capillary tube 53b.

The refrigerant pipe 200p (shown by a dashed line) is configured to be in contact with the cooling plate 200, as in FIG. 10A. However, in FIG. 10B, the refrigerant pipe 200p is provided downstream of the second capillary tube 53b. The refrigerant that passes through the refrigerant pipe 200p merges with the downstream side of the capillary tube 53 and flows into the evaporator 14.

Therefore, in FIG. 10B, the cooling plate 200 is configured to be cooled by the refrigerant upstream of the evaporator 14. The three-way valve 300 can be switched to allow the refrigerant to flow through the capillary tube 53, so that the refrigerant can flow through the evaporator 14 while preventing the refrigerant from flowing through the refrigerant pipe 200p that contacts the cooling plate 200.

In this way, in this figure, cooling of the cooling plate 200 is suppressed while the three-way valve 300 is causing the refrigerant to flow to the capillary tube 53 side and preventing the refrigerant from flowing through the refrigerant piping 200p. During this time, the first circulation operation can be performed by driving the refrigerator compartment fan 9b to circulate air between the refrigerator compartment 2 and the cooling plate 200 while preventing air from flowing in from the evaporator 14. That is, in this modified example, as in the embodiment, the first circulation operation can be performed even while the freezer compartment 7 is being cooled (the compressor 24 is being driven), and a high humidity refrigerator compartment can be achieved.

Figure 10C is a schematic diagram showing the configuration around the cooling plate in variants 1 and 2. In the figure, the left side shows the interior of the refrigerator compartment, and the right side shows the rear side of the interior of the refrigerator compartment.

As shown in this figure, the refrigerant pipe 200p is arranged so as to be in contact with the back surface of the cooling plate 200. A first refrigerator compartment air duct 110 is provided on the refrigerator compartment side of the cooling plate 200.

In this way, instead of the second refrigerator compartment air duct 120 of the above embodiment, the cooling plate 200 is cooled by the refrigerant pipe 200p through which a low-temperature refrigerant flows, and the air in the first refrigerator compartment air duct 110 is cooled. That is, in variants 1 and 2, indirect cooling operation is performed.

Compared to the working example, in variants 1 and 2, the second refrigerator compartment air duct 120 is not required, which has the advantage of increasing the space available for the refrigerator compartment 2, etc. On the other hand, the configuration of variant 2 (Fig. 10B) requires the addition of a three-way valve 300 and two capillary tubes, which increases the number of parts that make up the refrigeration cycle, and increases the manufacturing work time required for connecting these parts, which can lead to higher costs.

Therefore, taking into consideration these advantages and disadvantages, this embodiment is considered to be the more desirable configuration in terms of ease of manufacturing, cost, etc.

In addition, the following effects are obtained as ancillary effects of the embodiments and variations of this disclosure:

First, frost is allowed to form during indirect cooling operation, in order to ensure the high cooling capacity mentioned above, as well as to prevent frost from forming inside the refrigerator compartment 2.

If frost does not form on the cooling plate 200, for example, if moisture in the refrigerator compartment 2 increases due to inflow when the door is opened and closed or evaporation from food, condensation or frost will form on the low-temperature wall surface in the refrigerator compartment 2 if the cooling plate 200 cannot frost (dehumidify). In particular, in the refrigerator of the embodiment, the refrigerator compartment 2 is adjacent to the freezer compartment 7 via the insulating partition wall 27, and the lower wall surface of the refrigerator compartment 2 (the refrigerator compartment 2 side of the insulating partition wall 27) is likely to be low and below 0°C, making it prone to frost. It is also possible to provide an electric heater on the upper part of the insulating partition wall 27, but in that case, energy-saving performance will be reduced. In addition, if a low-temperature storage space 36 with a lower temperature than the refrigerator compartment 2 is provided at the bottom of the refrigerator compartment 2 as in the embodiment, excessive heating with the electric heater is not possible.

In the embodiment, it is easy to control the temperature of the cooling plate 200 during indirect cooling operation so that it is lower than the lower wall surface of the refrigerator chamber 2, etc. By controlling in this manner, it is possible to make frost easier to form on the cooling plate 200 and prevent undesirable condensation or frost from forming on the lower wall surface of the refrigerator chamber 2, etc., and to dehumidify the humidity in the refrigerator chamber 2 to an appropriate range. If the humidity drops too much due to frosting, the first refrigerator chamber damper 151 and the second refrigerator chamber damper 152 are closed and defrosting operation is performed to return moisture to the refrigerator chamber 2.

In the embodiment, as shown in Fig. 13, the cooling plate temperature sensor 201 is used to control the cooling plate temperature _TDR during indirect cooling operation so that it is lower than the frost point of the refrigerator compartment 2, but in addition to this, it may be controlled so that it is lower than the heat insulating partition wall 27. This makes it possible to more reliably make the temperature of the cooling plate 200 during indirect cooling operation lower than the heat insulating partition wall 27 on the refrigerator compartment 2 side.

Figure 13 is a flowchart showing the basic control during cooling operation of the refrigerator compartment of the refrigerator according to the embodiment.

As shown in the figure, control of the cooling operation of the refrigerator compartment 2 is started (step S3-0), and the temperature _TDR measured by the cooling plate temperature sensor 201 is acquired (step S3-1).

Then, the frost point temperature _Tfp is estimated (step S3-2) from the relative humidity in the refrigerator compartment 2 and the temperature detected by the refrigerator compartment temperature sensor 41. Note that, in this embodiment, the relative humidity in the refrigerator compartment 2 is also an estimated value.

It is determined whether _TDR is larger than the frost point temperature _Tfp (step S3-3). If _TDR < _Tfp , the process returns to step S3-1 (step S3-5).

On the other hand, if T _DR ≧T _fp , one or more of the following operations (1) to (3) are selected (step S3-4), thereby lowering the temperature of the cooling plate 200.

(1) Increase the rotational speed of the compressor 24.

(2) Reduce the rotation speed of the refrigerator compartment fan 9b.

(3) Increase the rotation speed of the evaporator fan 9a.

The above operation (1) reduces the temperature of the evaporator 14 and reduces the temperature of the air in the second refrigerator air duct 120, so the amount of cooling by the second refrigerator air duct 120 can be increased and the temperature of the cooling plate 200 can be reduced.

The above operation (2) reduces the amount of air flowing through the first air duct 110 of the refrigerator compartment, thereby reducing the amount of heating of the cooling plate 200 by the air in the first air duct 110 of the refrigerator compartment, and lowering the temperature of the cooling plate 200.

The above operation (3) increases the amount of air flowing through the second refrigerator air duct 120, thereby increasing the amount of cooling provided by the air in the second refrigerator air duct 120 and lowering the temperature of the cooling plate 200.

Basically, it is desirable to estimate the frost point temperature _Tfp from the temperature and humidity in the refrigerator compartment 2 that are estimated in advance, and to adjust the rotation speeds of the compressor 24, the refrigerator compartment fan 9b, and the evaporator fan 9a in advance according to the outside air temperature. It is also desirable to store the estimated data as a database in the memory of the control device.

In addition, if the cooling plate temperature sensor 201 is not provided, it is advisable to adjust the rotation speeds of the compressor 24, the refrigerator compartment fan 9b, and the evaporator fan 9a in advance according to the expected frost point temperature, as described above. However, by providing the cooling plate temperature sensor 201, it becomes possible to respond to a wider variety of cases, specifically a wider range of outside air temperatures, and to respond to changes in temperature, humidity, and required cooling capacity inside the refrigerator compartment 2 due to door opening and closing, and frost can be more reliably formed on the cooling plate 200 and frost formation on the walls inside the refrigerator compartment 2 can be suppressed.

In addition, to further improve the accuracy of estimating the frost point temperature, a refrigerator compartment humidity sensor that measures the humidity inside the refrigerator compartment may be provided. By using the refrigerator compartment humidity sensor and refrigerator compartment temperature sensor 41, the frost point temperature can be calculated from the actual temperature and humidity conditions inside the refrigerator compartment, and the temperature can be more accurately controlled to below the frost point temperature.

In addition, in order to reliably obtain the effects of suppressing the decrease in absolute humidity through indirect cooling operation and realizing a high-humidity refrigerator compartment with humidification and defrosting functions through the first circulation operation in the embodiment, it is desirable to perform the following control in the embodiment.

As shown in FIG. 9, cooling of the refrigerator compartment 2 is stopped until the first or second circulation operation is completed. This makes it possible to prevent frost from remaining unmelted. If the configuration allows for second circulation operation, the humidifying effect of the first circulation operation is the main purpose, and it is not necessary to melt the frost on the cooling plate 200. However, in the embodiment, in order to prevent frost from growing over a long period of time, cooling of the refrigerator compartment 2 is stopped until the first circulation operation is completed, minimizing the amount of frost remaining unmelted.

In addition, considering that the main purpose is the humidifying effect of the first circulation operation, it is not necessary to reliably melt the frost every time the first circulation operation is performed. For example, cooling of the refrigerator compartment 2 may be performed even if the end condition of the first circulation operation is not met. However, if the end condition of the first circulation operation is not met for two consecutive times, cooling of the refrigerator compartment 2 may be stopped until the first circulation operation is completed.

9, the first circulation operation is terminated when the cooling plate temperature _TDR detected by the cooling plate temperature sensor 201 reaches or exceeds a predetermined temperature _{TDR_off} that is higher than the frost melting temperature of 0° C. That is, it is detected that the temperature of the cooling plate 200 exceeds the frost melting temperature, and the frost on the cooling plate 200 is prevented from remaining unmelted.

For example, the cooling plate temperature sensor 201 may not be provided, and the first circulation operation may be performed for a certain period of time. In this case, however, the state of the cooling plate 200 cannot be detected, and there is a concern that the frost may not melt. In addition, when the control (step S-R1) is performed to stop cooling of the refrigerator compartment 2 until the above-mentioned first circulation operation is completed, if the defrosting time is extended to take into account the remaining frost, there is a concern that the start of the cooling operation may be delayed and the temperature of the refrigerator compartment 2 may rise. For this reason, it is necessary to end the first circulation operation at an appropriate time. Therefore, it is desirable to use the cooling plate temperature sensor 201 to determine the end of the first circulation operation at an appropriate time.

Furthermore, even if control (step S-R1) for stopping cooling of the refrigerator compartment 2 is not performed until the first circulation operation is completed, by providing a cooling plate temperature sensor 201 and controlling to stop the first circulation operation when the cooling plate temperature _TDR reaches a predetermined temperature, it is possible to suppress unnecessary operation of the refrigerator compartment fan 9b when the temperature of the cooling plate 200 rises and becomes higher than the dew point temperature of the refrigerator compartment 2 and humidification is not possible. This is also desirable from the viewpoint of energy saving performance.

2, 6A and 6B, the vacuum insulation material 25 provided on the rear wall is arranged so as to cover the approximate rear surface of the second refrigerator air duct 120 through which the low-temperature air from the evaporator 14 flows during indirect cooling operation. As described above, the refrigerator 1 basically cools the refrigerator compartment 2 by indirect cooling operation via the cooling plate 200 in order to keep the humidity inside the refrigerator compartment 2 high. For this reason, the cooling time is likely to be longer than when cooling is performed by direct cooling operation. In this case, the rear surface of the second refrigerator air duct 120 is low temperature and the temperature difference with the outside air is large for a long time, so this part is likely to receive a lot of heat from the outside air. From the viewpoint of suppressing such heat intrusion, it is desirable to provide the vacuum insulation material 25 so as to cover the approximate rear surface of the second refrigerator air duct 120. This can also prevent a decrease in energy-saving performance.

Next, we will explain the control of the cooling plate 200 during defrosting operation of the evaporator 14.

11 is a graph showing an example of temperature change during defrosting operation of the evaporator in the refrigerator according to the embodiment. The horizontal axis indicates time, and the vertical axis indicates the temperature of each part and the operating state of each part. The temperature changes are shown for the vegetable compartment, the refrigerator compartment, the cooling surface (cooling plate), the freezer compartment, and the evaporator. In addition, as values corresponding to these temperatures, the defrosting reference temperature T _{DR_off} of the cooling plate, a predetermined temperature T _{DR_off2} at which the defrosting of the cooling plate is considered to be reliably completed, the reference lower limit temperature T _{F_off} of the freezer compartment, and a lower limit temperature T _{F_off2} lower than T _{F_off} are shown.

On the horizontal axis of this figure, _td0 indicates the start time of the defrosting operation, _td1 indicates the time when the freezer compartment temperature T _F reaches the lower limit temperature T _{F_off2} , _td2 indicates the time when the evaporator temperature T _DF becomes T _{DF_off} which is sufficiently higher than the frost melting temperature, _td3 indicates the time when the drainage time Δt _d2 has elapsed after the end of the defrosting operation, _td4 indicates the time when the refrigerator compartment fan 9b is stopped, and _td5 indicates the time when the power supply to the cooling plate auxiliary heater 202 is stopped.

At _td1 , the compressor 24 and the evaporator fan 9a are stopped, and power is applied to the defrost heater 21 and the cooling plate auxiliary heater 202. After _td0 and before _td1 , the vegetable compartment damper 160 is closed. At _td2 , power is applied to the defrost heater 21. At _td3 , power is applied to the compressor 24, the evaporator fan 9a, and the refrigerator compartment fan 9b, and the refrigerator compartment first damper 151 and the vegetable compartment damper 160 are opened. During the defrosting operation shown in this figure, the refrigerator compartment second damper 152 is closed.

As shown in the figure, at _td1 , the defrost heater 21 is energized, so the temperature of the evaporator rises sharply and becomes constant at the melting point of the frost adhering to the evaporator. When all the frost on the evaporator melts, the temperature of the evaporator rises again. At _td1 , the cooling plate auxiliary heater 202 is energized, so the temperature of the cooling surface also rises. Furthermore, at _td1 , the compressor 24 and the evaporator fan 9a are stopped, so the temperature of the freezer compartment also rises.

Figure 12 is a flowchart showing the basic control of the defrosting operation of the evaporator in the refrigerator according to the embodiment.

Note that explanations of parts common to Figures 8 and 9 will be omitted.

There are a number of conditions for starting the defrosting operation in the refrigerator 1 of the embodiment, but in Fig. 12, during the cooling operation (step S2-0), for example, when the integrated rotation speed of the compressor 24 reaches a predetermined value and it is determined that the defrosting operation should be started (time _td0 , step S2-1 is Yes), a pre-cooling operation is started (step S2-2) to cool the freezer compartment 7 to a lower temperature than usual. When the pre-cooling operation starts, the cooling of the refrigerator compartment 2 is stopped and the first circulation operation is started (step S2-2). This suppresses the temperature rise of the freezer compartment 7 during the defrosting operation, and allows the second defrosting, which will be described later, to be completed in a short time.

The pre-cool operation ends after a predetermined time Δt _d1 (e.g., 30 minutes) has elapsed or when the freezer compartment temperature T _F falls below T _{F_off2} (e.g., below -24°C), which is lower than the normal predetermined temperature T _{F_off} (time t _d1 , step S2-3), and the compressor 24 and evaporator fan 9a are stopped, and defrosting operation of the evaporator 14 is started by applying power to the defrost heater 21 (step S2-4).

When the defrosting operation of the evaporator 14 is started, the second circulation operation to defrost the cooling plate 200 also starts.

First, we will explain the control during defrosting operation of the evaporator 14.

By turning off the compressor 24 and the evaporator fan 9a and turning on the defrost heater 21, the evaporator 14 and the frost adhering to the evaporator 14 are heated by the defrost heater 21, and the temperature gradually rises. When the temperature reaches the melting temperature (0°C), the frost adhering to the evaporator 14 melts. When the evaporator temperature T _DF detected by the evaporator temperature sensor 40 reaches T _{DF — off} (for example, 10°C) that is sufficiently higher than the melting temperature of the frost (time t _d2 , step S2-5), the defrost heater 21 is turned off and the defrosting operation is terminated (step S2-6). After the defrosting operation is terminated, the cooling operation is resumed (step S2-8) after a drainage time Δt _d2 (for example, 3 minutes) has elapsed (time t _d3, step S2-7).

Next, we will explain the control related to the second circulation operation.

While the first circulation operation is aimed at humidification and defrosting, the second circulation operation is aimed primarily at defrosting the cooling plate 200, and is an operation for more reliably melting the frost on the cooling plate 200. Specifically, the second circulation operation utilizes the time during which the evaporator 14 is defrosted, during which the compressor 24 is usually stopped for a longer period of time than during cooling operation, to heat the cooling plate 200 to a higher temperature than the first circulation operation that is performed during cooling operation.

When the defrosting operation of the evaporator 14 is started at time t _d1 , the first damper 151 and the second damper 152 are closed and the fan 9b is driven, as in the first circulation operation. Furthermore, in the second circulation operation, the auxiliary heater 202 is energized (step S2-11). As a result, the cooling plate 200 is heated by heat exchange between the cooling chamber 2 and the cooling plate 200, and the cooling plate is heated with a high heating amount by energizing the auxiliary heater 202. The average power (power per minute) of the auxiliary heater 202 is reduced to 50% of the power of the auxiliary heater 202 by duty control. When the cooling plate temperature T _DR reaches the end temperature T _{DR —} off of the first circulation operation (for example, 2° C.) in this state (step S2-12), the auxiliary heater 202 is energized and the fan 9b is stopped (step S2-13). The predetermined temperature used to stop the refrigerator compartment fan 9b (the judgment temperature in step S2-12) may be set separately from the end temperature T _{DR — off} of the first circulation operation.

Thereafter, when the cooling plate temperature T _DR is higher than T _{DR_off} and reaches a predetermined temperature T _{DR_off2} or higher (e.g., 8° C. or higher) at which it is considered that defrosting has been reliably completed (step S2-14), the power supply to the cooling plate auxiliary heater 202 is stopped, and the second circulation operation is terminated (step S2-15).

As shown in Figure 9, if the second circulation operation continues after the compressor 24 is driven, the refrigerator compartment 2 is not cooled in order to prevent any remaining frost from melting (see step S-R1 in Figure 9).

Therefore, if the second circulation operation takes longer than the defrost operation of the evaporator 14 (step S2-9 is No), and the second circulation operation continues after the defrost operation of the evaporator 14 ends, the duty of the duty control of the cooling plate auxiliary heater 202 is increased to 100% and the average power is increased to 30 W (step S2-10) so that the second defrost ends in a short time.

The above is the defrosting operation of the evaporator 14 in this embodiment.

Next, we will explain the effects of the above control in addition to those described above.

In the second circulation operation, unlike the first circulation operation performed during the cooling operation, electricity is applied to the cooling plate auxiliary heater 202. In the first circulation operation, defrosting is performed by heat exchange between the refrigerator compartment 2 and the cooling plate 200, so the temperature of the cooling plate 200 cannot be made higher than that of the refrigerator compartment 2.

On the other hand, when an electric heater is used, the temperature of the cooling plate 200 can be made higher than that of the refrigerator compartment 2. However, in addition to the power consumed to power the electric heater, energy is also required for cooling to remove the heat required to heat the cooling plate 200 in the next cooling operation, which increases the amount of power consumed.

Therefore, while the first circulation operation is performed about 10 times a day, the second circulation operation is performed in conjunction with the defrosting operation of the evaporator 14, which is performed less frequently, about once a day. Because it is performed less frequently, it is possible to suppress an increase in the amount of power consumed by the electric heater. On the other hand, the cooling plate 200 is heated to a relatively high temperature once a day, so that the frost on the cooling plate 200 can be reliably melted. In other words, this makes it possible to achieve a high humidity refrigerator compartment 2 as described in the cooling operation, while still providing a highly reliable refrigerator.

When the cooling plate temperature T _DR reaches T _{DR_off} , which is lower than the end temperature T _{DR_off2} of the second circulation operation (step S2-12), the cooling plate auxiliary heater 202 is kept energized while the refrigerator compartment fan 9b is stopped (step S2-13). This is to prevent the cooling plate auxiliary heater 202 from making the temperature of the cooling plate 200 higher than that of the refrigerator compartment 2, causing the air in the refrigerator compartment 2 to heat up and rise in temperature, and to prevent the cooling plate 200 from being cooled by the air in the refrigerator compartment 2, which would hinder defrosting.

The above-mentioned effect is particularly advantageous because the cooling plate auxiliary heater 202 is used to make the temperature of the cooling plate 200 higher than that of the refrigerator compartment 2. For example, the cooling plate auxiliary heater 202 may be turned off until the refrigerator compartment fan 9b is stopped (steps S2-11 to S2-13), and the cooling plate auxiliary heater 202 may be energized after the refrigerator compartment fan 9b is stopped to suppress heat exchange between the air in the refrigerator compartment 2 and the cooling plate 200.

On the other hand, in the example of FIG. 12, in order to ensure that the second circulation operation does not continue even after the defrosting operation of the evaporator 14 is completed and thus affect the cooling operation (so that S-R1 in FIG. 9 does not become No), the cooling plate auxiliary heater 202 is energized at a low duty while the refrigerator compartment fan 9b is being driven (steps S2-11 to S2-13).

In addition, the second circulation operation may be performed by stopping the refrigerator compartment fan 9b immediately after starting the operation and defrosting only with the cooling plate auxiliary heater 202. However, by driving the refrigerator compartment fan 9b while the cooling plate 200 is relatively low temperature (step S2-12 is No), the refrigerator compartment 2 can be cooled and the cooling plate 200 can be heated by heat exchange between the air in the refrigerator compartment 2 and the cooling plate 200 (the same effect as the first circulation operation can be obtained), and the defrosting time can be shortened and the energy saving performance can be improved. In addition, since the humidification effect of the refrigerator compartment 2 due to the mass transfer from the frost on the cooling plate 200 described in the first circulation operation can be obtained, in order to more reliably realize a high humidity refrigerator compartment 2, it is desirable to drive the refrigerator compartment fan 9b with the refrigerator compartment first damper 151 and the refrigerator compartment second damper 152 stopped even during the second circulation operation until the predetermined temperature is reached.

In addition, in conjunction with the defrosting operation of the evaporator 14, the second circulation operation was performed to defrost the cooling plate 200 more reliably than the normal first circulation operation, but it does not necessarily have to be performed in conjunction with the heating of the evaporator 14. For example, the second circulation operation may be performed once every three first circulation operations. However, it is preferable to perform the second circulation operation during the defrosting operation of the evaporator 14, when the compressor 24 is stopped for a relatively long time. This makes it possible to heat the cooling plate 200 to a higher temperature than during the first circulation operation, without affecting the cooling operation or while minimizing the effect. Another advantage is that by synchronizing the second circulation operation with the defrosting operation of the evaporator 14, there is no need to provide a dedicated timer or counter to measure the start timing of the second circulation operation.

The second circulation operation may be controlled, for example, without providing the cooling plate temperature sensor 201, so that the second circulation operation time is longer than the first circulation operation time. However, the second circulation operation is required to defrost more reliably than the first circulation operation, and the temperature of the cooling plate 200 becomes higher than that of the refrigerator compartment 2. During this time, heat exchange between the air in the refrigerator compartment 2 and the cooling plate 200 will result in heating of the refrigerator compartment 2 and cooling of the cooling plate 200. Therefore, it is desirable to use the cooling plate temperature sensor 201 to carry out the control shown in steps S2-12 to S2-14.

Also, as in step S-R1 of FIG. 9, by stopping the cooling of the refrigerator compartment 2 until the second circulation operation is completed in addition to the first circulation operation, it is possible to prevent frost from remaining unmelted during the second circulation operation, just as in the first circulation operation. This is more important during the second circulation operation. The second circulation operation raises the temperature of the cooling plate 200 more than the first circulation operation, and is an operation that more reliably removes frost, so it is necessary to prevent frost from remaining unmelted even more than in the first circulation operation. Therefore, to prevent the second circulation operation from ending prematurely due to the cooling operation of the refrigerator compartment 2, a control is provided that stops the cooling of the refrigerator compartment 2 until the second circulation operation is completed.

As described above, the first circulation operation is performed during the pre-cool operation (step S2-3), and the second circulation operation is started with the temperature of the cooling plate 200 already elevated. As described above, assuming that the second circulation operation is longer than the defrost operation of the evaporator 14, if the second circulation operation continues after the defrost operation of the evaporator 14 is completed, control is provided to increase the duty of the cooling plate auxiliary heater 202 (step S2-10). However, it is basically desirable to suppress the amount of electricity supplied to the cooling plate auxiliary heater 202. Therefore, by starting the second circulation operation with the temperature of the cooling plate 200 elevated, it is possible to minimize the occurrence of a state in which the time of the second circulation operation is longer than the defrost time of the evaporator 14, that is, a state in which the refrigerator compartment 2 cannot be cooled even after the compressor 24 is driven.

The cooling plate auxiliary heater 202 uses a heater with a maximum power of 30 W, which generates less heat than the defrost heater 21, which generates 150 W. The evaporator 14 needs to discharge all frost in a defrost operation once a day, but the cooling plate 200 discharges frost appropriately through the first circulation operation, which is performed about 10 times a day. For this reason, the amount of heat required to melt the frost in the second circulation operation is small. In addition, while the heat source of the evaporator 14 is only the defrost heater 21, the air in the refrigerator compartment 2 also serves as a heat source for the cooling plate 200 while the cooling plate 200 is at a low temperature during the second circulation operation. In other words, since the refrigerator compartment fan 9b is driven with the first and second refrigerator compartment dampers 151 and 152 stopped until the predetermined temperature is reached during the first circulation operation and the second circulation operation, the cooling plate auxiliary heater 202 may be an electric heater that generates less heat than the defrost heater 21. Therefore, the cooling plate auxiliary heater 202 has relatively few constraints such as cost and safety.

The above embodiment and variant 1 relate to a refrigerator having a refrigerator compartment and a freezer compartment with a single evaporator, and maintaining high humidity in the refrigerator compartment. In variant 1, the refrigerant pipe 200p acts similarly to the evaporator, but since it is downstream of the gas-liquid separator 54, essentially all liquid refrigerant is vaporized in the evaporator 14 and the gas-liquid separator 54, and gas refrigerant flows in the refrigerant pipe 200p downstream of the gas-liquid separator 54, and no evaporation of the refrigerant occurs.

On the other hand, in the case of variant 2, the gas-liquid mixed refrigerant also flows through the refrigerant pipe 200p that is in contact with the cooling plate 200, so the refrigerant pipe 200p essentially functions as an evaporator.

According to the present disclosure, in a refrigerator in which the surface temperature of a cooling plate provided for cooling the refrigerator compartment is cooled to a temperature lower than the frost point temperature of the refrigerator compartment, the refrigerator compartment can be cooled in a short time, the humidity in the refrigerator compartment can be kept high, and condensation or frost can be prevented in undesirable areas in the refrigerator compartment.

The following describes a preferred embodiment of the refrigerator according to the present disclosure.

The refrigerator compartment has walls where the average temperature is below 0°C.

When the refrigerant flowing through the refrigerant piping is blocked or reduced, or when the cold air flowing through the second air passage is blocked or reduced, the refrigerator compartment fan is driven to perform circulation operation to exchange heat between the refrigerator compartment and the cooling plate, thereby controlling the air from the refrigerator compartment to flow to the cooling plate.

The circulation operation melts the frost that has built up on the cooling plate.

The cooling plate is cooled by the cold air flowing through the second air duct.

It also has a freezer compartment that is cooled by an evaporator.

It also has an electric heater to heat the cooling plate.

The circulation operation will continue until the specified time has elapsed.

A cooling plate temperature sensor is further provided to detect the temperature of the cooling plate, and the circulation operation is performed until the cooling plate temperature sensor reaches a predetermined temperature or until a predetermined time has elapsed after the predetermined temperature is reached.

The cold air flowing through the second air duct is kept blocked or reduced until the conditions for the specified time or temperature of circulation operation are met.

The circulation operation includes a first circulation operation and a second circulation operation. The first circulation operation is an operation in which the air in the refrigerator compartment is sent to a cooling plate while the refrigerator compartment is a closed space, thereby exchanging heat between the air in the refrigerator compartment and the cooling plate. The second circulation operation has a specified time that is longer or a specified temperature that is higher than that of the first circulation operation.

An electric heater is further provided to heat the cooling plate, and the second circulation operation is an operation in which, in the first circulation operation state, the cooling plate is further heated by the electric heater to defrost the cooling plate.

The system is further equipped with a defrost heater that heats the evaporator, and performs a defrost operation by passing electricity through the defrost heater to melt the frost on the evaporator, and the second circulation operation is performed during the defrost operation.

The embodiments of the present disclosure are not limited to the above-mentioned examples and modified examples 1 and 2, but include various modified examples. The above-mentioned examples and modified examples 1 and 2 have been described in detail to clearly explain the technical contents of the present disclosure, and are not necessarily limited to those having all of the configurations described. In addition, it is possible to add, delete, or replace some of the configurations of the above-mentioned examples and modified examples 1 and 2 with other configurations. For example, in the refrigerator of the example, when the evaporator fan 9a is driven, air is always blown into the freezer compartment 7, but a freezer compartment damper that controls the air blown into the freezer compartment 7 may be provided.

1: refrigerator, 2: refrigerator compartment, 3: ice maker, 4: upper freezer compartment, 5: lower freezer compartment, 6: vegetable compartment, 7: freezer compartment, 8: evaporator compartment, 9a: evaporator fan, 9b: refrigerator compartment fan, 10: insulated box, 10a: outer box, 10b: inner box, 14: evaporator, 16: hinge cover, 21: defrost heater, 22: evaporator drain, 23: evaporator gutter, 24: compressor, 25: vacuum insulation material, 27, 28, 29, 30: insulated partition wall, 39: machine room , 40: evaporator temperature sensor, 41: refrigerator compartment temperature sensor, 43: freezer compartment temperature sensor, 44: vegetable compartment temperature sensor, 50a: external radiator, 50b: wall surface heat dissipation piping, 50c: condensation prevention piping, 53: capillary tube, 54: gas-liquid separator, 57: heat exchanger, 151: refrigerator compartment first damper, 152: refrigerator compartment second damper, 160: vegetable compartment damper, 200: cooling plate, 201: cooling plate temperature sensor, 202: cooling plate auxiliary heater.

Claims (11)

A refrigerator compartment,
a refrigeration cycle in which a compressor, a radiator, a pressure reducing section, and an evaporator are connected in a ring shape by refrigerant piping;
A cooling plate having one surface facing the first air duct on the refrigeration compartment side;
an electric heater installed on the cooling plate;
a refrigerator compartment fan that pressurizes the air in the first air duct,
The other surface of the cooling plate has a configuration in which the other surface is in contact with a portion of the refrigerant piping from the pressure reducing portion to the suction side of the compressor, or a configuration in which the other surface faces a second air duct through which the cold air cooled by the evaporator flows,
The surface temperature of the cooling plate on the first air passage side is cooled to a temperature lower than the frost point temperature of the refrigerator compartment by the refrigerant flowing through the portion of the refrigerant piping or the cold air flowing through the second air passage,
In a state where the refrigerant flowing through the portion of the refrigerant piping is blocked or reduced, or in a state where the cold air flowing through the second air passage is blocked or reduced, the refrigerator compartment fan is driven to perform a circulation operation in which heat is exchanged between the refrigerator compartment and the cooling plate, thereby controlling so that the air from the refrigerator compartment flows to the cooling plate;
The circulation operation includes a first circulation operation and a second circulation operation,
The first circulation operation is an operation for humidifying the air in the refrigerator compartment and defrosting the cooling plate by exchanging heat between the cooling plate and the frost attached to the cooling plate and the air in the refrigerator compartment,
The refrigerator, wherein the second circulation operation is an operation for defrosting the cooling plate by energizing the electric heater. A refrigerator compartment,
a refrigeration cycle in which a compressor, a radiator, a pressure reducing section, and an evaporator are connected in a ring shape by refrigerant piping;
A cooling plate having one surface facing the first air duct on the refrigeration compartment side;
an electric heater installed on the cooling plate;
a refrigerator compartment fan that pressurizes the air in the first air duct,
The other surface of the cooling plate has a configuration in which the other surface is in contact with a portion of the refrigerant piping from the pressure reducing portion to the suction side of the compressor, or a configuration in which the other surface faces a second air duct through which the cold air cooled by the evaporator flows,
frosting the cooling plate on the first air passage side by the refrigerant flowing through the portion of the refrigerant piping or the cold air flowing through the second air passage;
In a state where the refrigerant flowing through the portion of the refrigerant piping is blocked or reduced, or in a state where the cold air flowing through the second air passage is blocked or reduced, the refrigerator compartment fan is driven to perform a circulation operation in which heat is exchanged between the refrigerator compartment and the cooling plate, thereby controlling so that the air from the refrigerator compartment flows to the cooling plate;
The circulation operation includes a first circulation operation and a second circulation operation,
The first circulation operation is an operation for humidifying the air in the refrigerator compartment and defrosting the cooling plate by exchanging heat between the cooling plate and the frost attached to the cooling plate and the air in the refrigerator compartment,
The refrigerator, wherein the second circulation operation is an operation for defrosting the cooling plate by energizing the electric heater. The refrigerator according to claim 1 or 2, wherein the refrigerator compartment is provided with a wall surface whose average temperature is less than 0°C. The refrigerator according to claim 1 or 2, wherein the frost adhering to the cooling plate is melted by the circulation operation. The refrigerator according to any one of claims 1 to 4, wherein the cooling plate is cooled by the cold air flowing through the second air passage. The refrigerator according to claim 5, further comprising a freezer compartment cooled by the evaporator. The refrigerator according to claim 1 or 2, wherein the circulation operation is performed until a predetermined time has elapsed. Further comprising a cooling plate temperature sensor for detecting a temperature of the cooling plate,
3. The refrigerator according to claim 1, wherein the circulation operation is performed until the cooling plate temperature sensor reaches a predetermined temperature or until a predetermined time has elapsed after the cooling plate temperature sensor reaches the predetermined temperature. The refrigerator according to claim 8, wherein the cold air flowing through the second air duct is kept blocked or reduced until the condition for the predetermined time or the predetermined temperature of the circulation operation is satisfied. The refrigerator according to claim 9, wherein the second circulation operation has a longer predetermined time or a higher predetermined temperature than the first circulation operation. The heating element further includes a defrosting heater for heating the evaporator.
A defrosting operation is performed by energizing the defrosting heater to melt the frost on the evaporator.
The refrigerator according to claim 10, wherein the second circulation operation is performed during the defrosting operation.

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