refrigerator

Abstract

The present invention provides a refrigerator that achieves highly efficient hot gas defrosting while suppressing liquid return from the compressor. [Solution] The refrigerator of the present invention comprises a cooling operation in which refrigerant discharged from a compressor flows in the order of a first refrigerant control means, a heat dissipation section, a pressure reducing means, a branch and confluence section, and an evaporator, returning to the compressor and cooling the evaporator, and a defrosting operation in which the first refrigerant control means is switched so that the refrigerant discharged from the compressor bypasses part or all of the heat dissipation section and the pressure reducing means, flows in the order of the first refrigerant control means, the branch and confluence section, and the evaporator, returning to the compressor and heating the evaporator, wherein the second refrigerant control means is provided in the middle of the refrigerant flow path in the cooling operation or between the outlet of the heat dissipation section and the branch and confluence section, and the defrosting operation can be performed with the second refrigerant control means blocked and the refrigerant accumulating in the heat dissipation section.

Description

[Technical Field]

[0001] This invention relates to a refrigerator. [Background technology]

[0002] Patent Document 1 describes a hot gas defrosting method (hereinafter referred to as hot gas defrosting) that performs defrosting by supplying high-temperature refrigerant from the compressor to the evaporator, in addition to a defrosting heater (defrosting heating unit; electric heater). Hot gas defrosting is performed after and while heating the evaporator with the defrosting heater. This suppresses liquid return of liquefied refrigerant back to the compressor during hot gas defrosting. It is noted that hot gas defrosting is performed because it has effects such as reducing the energy required for defrosting compared to defrosting with a defrosting heater (see paragraphs 0003 and 0004 of Patent Document 1). On the other hand, liquid return, which is a problem in hot gas defrosting, is suppressed by preheating the evaporator with an electric heater and by exchanging heat between the refrigerant piping (hereinafter referred to as defrosting pipe) that allows high-temperature refrigerant from the compressor to flow to the evaporator during defrosting operation and the refrigerant piping (hereinafter referred to as suction pipe) that allows the refrigerant to return from the evaporator to the compressor, thereby warming the refrigerant from the evaporator to the compressor. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 7445287 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, the liquid return suppression method described in Patent Document 1 has the following problems.

[0005] During hot gas defrosting, an electric heater is used to heat the evaporator to prevent liquid return, thus reducing the energy used for heating the evaporator and minimizing the effect of hot gas defrosting. In other words, while the system is configured to achieve hot gas defrosting, the aforementioned effect of hot gas defrosting is reduced. In addition, some of the energy from the electric heater is used to vaporize the refrigerant, which also makes it energy inefficient.

[0006] Furthermore, another method for suppressing liquid return, which involves heat exchange between the defrosting pipe and the suction pipe, is fundamentally incapable of controlling the amount of heat exchange. Therefore, it is difficult to suppress liquid return solely through this heat exchange. Moreover, since the energy of the refrigerant discharged from the compressor is consumed to heat the refrigerant returning to the compressor, the heating efficiency of the evaporator also decreases. In addition, since defrosting pipes and suction pipes generally tend to have large pressure losses, both require relatively large diameter refrigerant piping, making them more difficult to manufacture compared to the heat exchange section using soldered thin capillary tubes and suction pipes commonly used in refrigerators.

[0007] In view of the above, the present invention aims to provide a refrigerator that achieves highly efficient hot gas defrosting while suppressing liquid return from the compressor. [Means for solving the problem]

[0008] To achieve the above objective, the refrigerator of the present invention comprises a storage chamber, an evaporator for cooling the storage chamber, a compressor, a heat dissipation unit, a pressure reducing means, a first refrigerant control means for switching the refrigerant flow path, a second refrigerant control means capable of blocking the refrigerant flow path, and a branching / merging unit capable of merging and branching the refrigerant flow paths. The refrigerant discharged from the compressor flows in the following order: the first refrigerant control means, the heat dissipation unit, the pressure reducing means, the branching and merging unit, and the evaporator, before returning to the compressor and cooling the evaporator in a cooling operation. The system includes a defrosting operation in which the first refrigerant control means is switched so that the refrigerant discharged from the compressor bypasses part or all of the heat dissipation unit and the pressure reducing means, flows in the order of the first refrigerant control means, the branching and merging unit, and the evaporator, and returns to the compressor to heat the evaporator, The second refrigerant control means is provided in the refrigerant flow path during the cooling operation, either midway through the heat dissipation section or between the outlet and the branch / confluence section. The defrosting operation can be performed with the second refrigerant control means blocked, causing the refrigerant to accumulate in the heat dissipation section. [Brief explanation of the drawing]

[0009] [Figure 1] This is a front view showing the configuration of the refrigerator according to the first embodiment. [Figure 2] This is a cross-sectional view taken along line II-II, as shown in Figure 1. [Figure 3] This is a schematic diagram showing the configuration of the refrigeration cycle (refrigerant flow path) in the refrigerator of the first embodiment. [Figure 4A] This is an explanatory diagram showing the flow of refrigerant during cooling operation in the refrigerator of the first embodiment. [Figure 4B] This is an explanatory diagram showing the flow of refrigerant during defrosting operation in the refrigerator of the first embodiment. [Figure 5] This is a control flowchart for defrosting operations. [Figure 6] This is an example of a time chart for defrosting operation. [Figure 7] This is a schematic diagram showing the configuration of the refrigeration cycle in the refrigerator of the second embodiment. [Figure 8] This is a cross-sectional view of the refrigerator according to the third embodiment. [Figure 9] This is a schematic diagram showing the configuration of the refrigeration cycle in the refrigerator of the third embodiment. [Figure 10A] This is an explanatory diagram showing the flow of refrigerant during refrigeration operation in the refrigerator of the third embodiment. [Figure 10B] This is an explanatory diagram showing the flow of refrigerant during refrigeration operation in the refrigerator of the third embodiment. [Figure 10C]It is an explanatory diagram showing the flow of refrigerant during defrosting operation in the refrigerator of the third embodiment. [Figure 11] It is a schematic diagram showing a first modification of the refrigeration cycle of the third embodiment. [Figure 12] It is a schematic diagram showing a second modification of the refrigeration cycle of the third embodiment.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail with reference to the drawings. Note that each drawing only schematically shows the invention to such an extent that the invention can be sufficiently understood. Therefore, the present invention is not limited only to the illustrated examples. Also, in each drawing, common components and similar components are denoted by the same reference numerals, and redundant descriptions thereof are omitted.

[0011] [First Embodiment] Hereinafter, the configuration of the refrigerator 1 of the first embodiment will be described with reference to FIGS. 1 to 2. FIG. 1 is a front view showing the configuration of the refrigerator 1 of the first embodiment. FIG. 2 is a cross-sectional view taken along line II-II shown in FIG. 1. In the following description, the 6-door refrigerator 1 will be described as an example, but the refrigerator 1 is not limited to 6 doors.

[0012] The refrigerator 1 has functions of performing a cooling operation and a defrosting operation. The cooling operation is an operation of cooling the storage chamber by evaporation of the low-temperature and low-pressure refrigerant passing through the capillary tube 53 in the evaporator 14. The defrosting operation is an operation of removing the frost adhering to the evaporator 14 (FIG. 2).

[0013] As shown in Figure 1, the insulated box 10 of the refrigerator 1 has storage compartments in the following order from top to bottom: a refrigerator compartment 2, ice-making compartments 3 and an upper freezer compartment 4 located on the left and right sides, a lower freezer compartment 5, and a vegetable compartment 6. The refrigerator 1 is equipped with doors to open and close the openings of each storage compartment. These doors consist of two rotating doors 2a and 2b for the refrigerator compartment 2, which are divided into left and right sections to open and close the opening of the refrigerator compartment 2, and two pull-out doors 3a for the ice-making compartment 3, 4a for the upper freezer compartment 4, 5a for the lower freezer compartment 5, and 6a for the vegetable compartment 6, which open and close the openings of the ice-making compartment 3, the upper freezer compartment 4, the lower freezer compartment 5, and the vegetable compartment 6, respectively. Door hinges (not shown) are provided at the top and bottom of the refrigerator compartment 2 to fix the doors 2a and 2b of the refrigerator compartment 2 to the refrigerator 1, and the upper door hinge is covered with a door hinge cover 16.

[0014] Refrigerator compartment 2 and vegetable compartment 6 are refrigerated storage compartments that maintain a temperature range of refrigeration (above 0°C). For example, refrigerator compartment 2 is maintained at approximately 4°C, and vegetable compartment 6 at approximately 6°C. Ice maker compartment 3, upper freezer compartment 4, and lower freezer compartment 5 are frozen storage compartments that maintain a temperature range of freezing (below 0°C), for example, on average at around -20°C. Note that ice maker compartment 3, upper freezer compartment 4, and lower freezer compartment 5, which are frozen storage compartments, may sometimes be referred to as freezer compartment 7.

[0015] As shown in Figure 2, the refrigerator 1 is constructed with an insulated box 10 formed by filling the space between an outer box 10a (made of steel plate) and an inner box 10b (made of synthetic resin) with foamed insulation material (e.g., polyurethane foam), thereby separating the outside from the inside of the refrigerator. In addition to foamed insulation material such as polyurethane foam, the insulated box 10 is further enhanced by installing vacuum insulation material 25, which has a lower thermal conductivity than foamed insulation material, between the outer box 10a and the inner box 10b, thereby improving insulation performance without reducing the food storage volume. Here, the vacuum insulation material 25 is constructed by wrapping a core material such as glass wool with an outer packaging material. The outer packaging material includes a metal layer (e.g., aluminum) to ensure gas barrier properties. The vacuum insulation material 25 is installed in the ceiling wall, left and right walls, back wall, and bottom wall of the insulated box 10, and is also inserted into the door 5a of the lower freezer compartment 5, which is a relatively large freezer storage compartment, to improve insulation performance.

[0016] The refrigerator compartment 2 is separated from the ice-making compartment 3 and the upper freezer compartment 4, which are adjacent to it below, by an insulating partition wall 28. The lower freezer compartment 5 and the vegetable compartment 6 are separated by an insulating partition wall 29. In addition, an insulating partition wall 30 is provided on the front side between the ice-making compartment 3, the upper freezer compartment 4, and the lower freezer compartment 5 to prevent air from inside the refrigerator 1 from leaking out through the gaps in the doors 3a, 4a, and 5a, and to prevent outside air from entering each storage compartment. In the first embodiment, an electric heater (not shown) is provided at the bottom of the insulating partition wall 29 to heat the vegetable compartment 6 so that it does not become excessively cold.

[0017] The doors 2a and 2b of the refrigerator compartment 2 are equipped with multiple door pockets 33a, 33b, and 33c on the inside. The inside of the refrigerator compartment 2 is divided into multiple storage spaces by shelves 34a, 34b, 34c, and 34d. In addition, a low-temperature storage space 35 is provided in the lower part of the refrigerator compartment 2 (above the insulated partition wall 28). The low-temperature storage space 35 is also called the internal storage room. The low-temperature storage space 35 is kept at a particularly low temperature of approximately -1 to +1°C within the refrigerator compartment 2, and is configured as a nearly sealed space in which cold air is not directly blown into the low-temperature storage space 35. It is a space for storing foods that require low temperatures and drying prevention (such as meat and fish).

[0018] The ice-making compartment 3, the upper freezer compartment 4, the lower freezer compartment 5, and the vegetable compartment 6 are each provided with an ice-making container, an upper freezer container 4b, a lower freezer container 5b, and a vegetable compartment container 6b, which are pulled out together with the doors 3a, 4a, 5a, and 6a, respectively.

[0019] The evaporator 14 is housed in the evaporator chamber 8. The evaporator chamber 8 is composed of a freezer compartment air passage component 62 located approximately behind the freezer compartment 7 and an inner box 10b. The air in the evaporator chamber 8, which has been cooled by heat exchange with the evaporator 14, is blown into the freezer compartment 7 through the freezer compartment air passage 12 and the freezer compartment discharge port 12a provided in the freezer compartment air passage component 62 by the evaporator fan 9 located above the evaporator 14, thereby cooling the inside of the freezer compartment 7. The air blown into the freezer compartment 7 returns to the evaporator chamber 8 through the freezer compartment return port 17 provided in the freezer compartment air passage component 62 and is cooled again by the evaporator 14. In the refrigerator 1 of the first embodiment, the operation in which the air cooled by the evaporator 14 is blown by the evaporator fan 9 is called the cooling operation.

[0020] In the refrigerator 1 of the first embodiment, the refrigerator compartment 2 and the vegetable compartment 6 are also cooled with air cooled by the evaporator 14.

[0021] When cooling the refrigerator compartment 2, the refrigerator compartment damper 20 is opened during the cooling operation. The air in the evaporator compartment 8, which has been cooled by the evaporator 14, is blown by the evaporator fan 9 through the refrigerator compartment damper 20 and the refrigerator compartment air passage 11 to the refrigerator compartment 2 from the refrigerator compartment discharge port 11a, cooling the inside of the refrigerator compartment 2. The air blown into the refrigerator compartment 2 returns to the evaporator compartment 8 through the refrigerator compartment return air passage (not shown) provided in the refrigerator compartment air passage component 61, and is cooled again by the evaporator 14. The refrigerator compartment air passage 11 is an air passage composed of the refrigerator compartment air passage component 61 and the inner box 10b. The refrigerator compartment damper 20 is a component that opens and closes the air passage between the refrigerator compartment air passage 11 and the evaporator compartment 8. When the refrigerator compartment 2 is cold, closing the refrigerator compartment damper 20 suppresses the cooling of the refrigerator compartment 2.

[0022] To cool the vegetable compartment 6, open the vegetable compartment damper (not shown) during the cooling operation. The air in the evaporator chamber 8, which has been cooled by the evaporator 14, is blown into the vegetable compartment 6 by the evaporator fan 9 via the vegetable compartment air passage (not shown) and the vegetable compartment damper (not shown), cooling the inside of the vegetable compartment 6. The air blown into the vegetable compartment 6 returns to the bottom of the evaporator chamber 8 via the vegetable compartment cold air return air passage 18, which is located at the bottom of the insulated partition wall 29, and is cooled again by the evaporator 14. Although the cold air generated by the evaporator 14 is blown into the vegetable compartment 6, the cold air does not directly enter the vegetable compartment container 6b where food is stored, thereby suppressing the drying of vegetables. If the vegetable compartment 6 is cold, the cooling of the vegetable compartment 6 is suppressed by closing the vegetable compartment damper.

[0023] In refrigerator 1, when the door is opened or closed, moisture-laden air flows into the interior and enters the low-temperature evaporator 14 through the refrigerator compartment return port (not shown), the freezer compartment return port 17, and the vegetable compartment cold air return duct 18. When this air flows into the evaporator 14, moisture in the air condenses and adheres to the surface of the evaporator 14 as frost. As the frost grows, it hinders heat exchange between the evaporator 14 and the air, and the airflow through the evaporator 14 decreases due to the airflow resistance caused by the frost. Therefore, refrigerator 1 performs a defrosting operation, described later, to melt the frost on the evaporator 14.

[0024] The defrost water (melted water) generated during defrosting of the evaporator 14 falls into the freezer drain 23 located at the bottom of the evaporator chamber 8, and is discharged to the evaporation tray 32 located at the top of the compressor 24 via the drain port 22 and drain pipe 27.

[0025] The water discharged into the evaporation tray 32 is heated by the compressor 24 and the heat dissipation from the external heat exchanger 50a, and then vaporized by the airflow from the machine room fan 38 and discharged outside the refrigerator.

[0026] A refrigerator temperature sensor 41, a freezer temperature sensor 42, and a vegetable compartment temperature sensor 43 are provided on the rear side of the interior of the refrigerator compartment 2, freezer compartment 7, and vegetable compartment 6, respectively. An evaporator temperature sensor 40 is provided above the evaporator 14. These sensors detect the temperatures of the refrigerator compartment 2, freezer compartment 7, vegetable compartment 6, and evaporator 14. Inside the door hinge cover 16 on the ceiling of the refrigerator 1, there is an outside air temperature sensor 37a that detects the temperature of the outside air (air outside the refrigerator) and an outside air humidity sensor 37b that detects the humidity. Other sensors include door sensors (not shown) that detect the open / closed state of doors 2a, 2b, 3a, 4a, 5a, and 6a, respectively.

[0027] The machine room 39 of refrigerator 1 houses a control board 31 (control device, control unit) which is part of the control system and includes a CPU (Central Processing Unit), memory such as ROM (Read Only Memory) and RAM (Random Access Memory), interface circuits, etc. The control board 31 is connected to an outside air temperature sensor 37a, an outside air humidity sensor 37b, a refrigerator compartment temperature sensor 41, a freezer compartment temperature sensor 42, a vegetable compartment temperature sensor 43, an evaporator temperature sensor 40, and various door sensors via electrical wiring (not shown).

[0028] Furthermore, the control board 31 controls the compressor 24, evaporator fan 9, machine room fan 38, refrigerator compartment damper 20, and vegetable compartment damper based on the output values ​​of each sensor, the settings of the operation unit 26, and programs pre-recorded in the ROM. The operation unit 26 is located in the inner box 10b of the refrigerator compartment 2 (Figure 2), and can be used to adjust the temperature of the refrigerator compartment 2, the freezer compartment 7, and the vegetable compartment 6, as well as to issue instructions for additional functions, such as a rapid freezing function to increase the cooling capacity of the freezer compartment 7.

[0029] The configuration and operation of the refrigeration cycle (refrigerant flow path) 201 in refrigerator 1 will be described below with reference to Figures 3 and 4A to 4B. Figure 3 is a schematic diagram showing the configuration of the refrigeration cycle (refrigerant flow path) 201 in refrigerator 1 of the first embodiment. Figure 4A is an explanatory diagram showing the flow of refrigerant during cooling operation in refrigerator 1. Figure 4B is an explanatory diagram showing the flow of refrigerant during defrosting operation in refrigerator 1.

[0030] As shown in Figure 3, the refrigerator 1 is equipped with a compressor 24, a three-way valve 101, a check valve 130, a heat dissipation unit 50, a dryer 51, a two-way valve 52c, a capillary tube 53c, an evaporator 14, a gas-liquid separator 54, and a first branch junction 211.

[0031] The compressor 24 is a component that compresses the refrigerant.

[0032] The heat dissipation section 50 is a component that releases heat from the refrigerant. Here, the heat dissipation section 50 is described as having an external heat radiator 50a and wall-surface heat dissipation piping 50b that dissipate heat from the refrigerant, and condensation prevention piping 50c that suppresses condensation on the front surface of the insulated partition walls 28, 29, and 30.

[0033] The dryer 51 is a component that removes moisture from the refrigeration cycle.

[0034] The two-way valve 52c is a refrigerant control means that can switch between opening and closing the refrigerant flow path from the dryer 51 to the capillary tube 53c.

[0035] The capillary tube 53c is a means of reducing the pressure of the refrigerant.

[0036] As explained in Figure 2, the evaporator 14 is a component that cools the return air from each of the storage chambers 2, 6, and 7.

[0037] The gas-liquid separator 54 is a component that separates the liquid refrigerant from the gaseous refrigerant and prevents the liquid refrigerant from flowing into the compressor 24.

[0038] The first branch junction 211 is the point where the refrigerant flow path for cooling operation and the first defrosting refrigerant flow path 59 for defrosting merge.

[0039] The check valve 130 is a component that suppresses the backflow of refrigerant (referring to the flow from the external heat exchanger 50a to the outlet 101a of the three-way valve 101).

[0040] The three-way valve 101 is a refrigerant control means that switches the direction of refrigerant flow depending on whether cooling operation or defrosting operation is being performed. The three-way valve 101 has an outlet 101a connected to the external radiator 50a via refrigerant piping and an outlet 101b connected to the first branch junction 211, and can switch the outlet through which the refrigerant flows.

[0041] Refrigerator 1 has a refrigerant flow path so that the refrigerant flows between these components.

[0042] Here, the refrigerant flow path from the gas-liquid separator 54 to the compressor 24, that is, the refrigerant flow path that returns the refrigerant to the compressor 24, is called the suction pipe 57.

[0043] The refrigerant flow path connecting the outlet 101b of the three-way valve 101 to the first branch junction 211, which guides the high-temperature refrigerant discharged from the compressor 24 to the evaporator 14 during defrosting operation, is called the first defrosting refrigerant flow path 59.

[0044] Furthermore, the refrigerator 1 has an internal heat exchange section 58. The internal heat exchange section 58 is a heat exchange section in which part or all of the capillary tube 53 can exchange heat with part of the suction pipe 57. In the refrigerator 1 of the first embodiment, the capillary tube 53c is soldered to the suction pipe 57. By fixing the connection with a metal member through soldering, the refrigerator 1 improves the heat exchange efficiency. Note that the internal heat exchange section 58 only needs to be such that the capillary tube 53c and the suction pipe 57 can exchange heat in close proximity.

[0045] Furthermore, in this embodiment, the refrigerator 1 is described as using isobutane, a flammable refrigerant, as the refrigerant. The compressor 24 is described as being equipped with an inverter, allowing its rotational speed to be changed.

[0046] Refer to Figures 4A and 4B to explain the refrigerant flow during cooling and defrosting operations.

[0047] <Refrigerant flow during cooling operation> As shown in Figure 4A, during cooling operation, the three-way valve 101 opens the outlet 101a on the heat dissipation section 50 side and closes the outlet 101b so that the refrigerant flows to the heat dissipation section 50 (external heat radiator 50a). The two-way valve 52c is left open so that the refrigerant flows to the capillary tube 53c.

[0048] The following describes the components through which the refrigerant flows during cooling operation. In refrigerator 1, when the compressor 24 is driven, the refrigerant is compressed into a high-temperature, high-pressure gaseous refrigerant. The high-temperature, high-pressure gaseous refrigerant passes through the three-way valve 101, then flows through the external heat exchanger 50a, the wall heat dissipation pipe 50b, and the condensation prevention pipe 50c to dissipate heat and become a liquid refrigerant. After this, the refrigerant flows through the dryer 51 to remove moisture and then reaches the two-way valve 52c. The refrigerant that has passed through the two-way valve 52c is then depressurized in the capillary tube 53c to become a low-temperature, low-pressure gas-liquid two-phase refrigerant, and then reaches the evaporator 14 via the first branch junction 211. In refrigerator 1, as shown in Figure 2, the evaporator fan 9 drives return air from each storage compartment 2, 6, and 7 into the evaporator compartment 8 equipped with the evaporator 14. As it passes through the evaporator 14, it exchanges heat with the low-temperature refrigerant in the piping of the evaporator 14, becoming low in temperature, and is then sent back to each storage compartment 2, 6, and 7. At this time, the refrigerant absorbs heat from the air in each storage chamber 2, 6, and 7 (see Figure 2), increasing its enthalpy and dryness, becoming a nearly saturated gaseous refrigerant. The refrigerant then reaches the outlet of the evaporator 14, passes through the gas-liquid separator 54 and the suction pipe 57, and returns to the compressor 24.

[0049] The suction pipe 57 is configured to exchange heat with the capillary tube 53c in the internal heat exchange section 58. The refrigerant passing through the suction pipe 57 is heated by the capillary tube 53c, causing its enthalpy to increase (its temperature to rise) before returning to the compressor 24. By providing such an internal heat exchange section 58, the refrigerator 1 can raise the temperature of the refrigerant drawn into the compressor 24. Therefore, the refrigerator 1 can raise the refrigerant temperature in the suction pipe 57 (Figure 3) within the machine room 39 (Figure 3) where outside air flows in and out, preventing condensation and frost formation on the suction pipe 57 within the machine room 39. In addition, the refrigerator 1 can reduce the enthalpy of the refrigerant flowing into the evaporator 14 by absorbing heat from the capillary tube 53c. Therefore, the refrigerator 1 can improve the cooling capacity of the evaporator 14. Furthermore, in a refrigerator 1 using a refrigerant such as isobutane, by providing an internal heat exchange unit 58, the cooling capacity can be improved and the compression power (power consumption wa) of the compressor 24 can be reduced, thereby improving the cooling efficiency (the ratio of the amount of heat cooled to the input of the compressor 24), i.e., the energy saving performance.

[0050] <Refrigerant flow during defrosting operation> As shown in Figure 4B, during defrosting operation, the three-way valve 101 opens the outlet 101b on the side of the first defrosting refrigerant flow path 59 that leads to the evaporator 14, and closes the outlet 101a. Even during defrosting operation, the compressor 24 is driven to compress the refrigerant into a high-temperature, high-pressure gaseous refrigerant. This high-temperature, high-pressure gaseous refrigerant passes through the three-way valve 101 and then flows to the evaporator 14 via the first branch junction 211, where it exchanges heat with the evaporator 14. As a result, the high-temperature refrigerant in the evaporator 14 releases heat, and the evaporator 14 is heated. After that, the refrigerant flows through the gas-liquid separator 54 and the suction pipe 57 and returns to the compressor 24.

[0051] In the refrigerator 1 of this embodiment, the defrosting operation shown in Figure 4B is performed, which involves heating the evaporator 14 by heat dissipation from the high-temperature refrigerant from the compressor 24 to melt the frost adhering to the evaporator 14.

[0052] Next, the defrost operation control of refrigerator 1 in this embodiment will be described. Figure 5 is a control flowchart related to the defrost operation, and Figure 6 is an example of a time chart during the defrost operation.

[0053] The freezer compartment temperature T is detected by the freezer compartment temperature sensor 42. F The evaporator temperature T detected by the evaporator temperature sensor 40 DF We will use [this method] and omit the details regarding the temperature and control of the vegetable compartment 6.

[0054] During the cooling operation of this embodiment (control S1-0), the two-way valve 52c is opened, the three-way valve 101 is opened on the outlet 101a side (the outlet 101b side is closed), and the compressor 24 is turned ON to form the refrigerant flow described in Figure 4A.

[0055] Although not shown in the diagram, during the cooling operation control shown in control S1-0, for example, the freezer chamber temperature T F If the compressor 24 turns OFF due to a pressure drop below a predetermined value, the refrigerator 1 in this embodiment closes the two-way valve 52c to prevent high-pressure refrigerant upstream of the capillary tube 53c from flowing into the evaporator 14. This maintains the pressure difference between the high-pressure heat dissipation section 50 and the low-pressure evaporator 14, and reduces the power required by the compressor 24 to create the pressure difference again when the compressor 24 is turned ON. In other words, energy saving is enhanced by closing the two-way valve 52c when the compressor 24 is OFF.

[0056] In this embodiment, there are several conditions for starting the defrosting operation in the refrigerator 1, but one is when, for example, the cumulative rotational speed of the compressor 24 reaches a predetermined value during the cooling operation (control S1-0) (time t d0、 Control S1-1) and the refrigerator compartment damper 20 are closed to start a pre-cooling operation that concentrates the cooling of the freezer compartment 7 (Control S1-2). The pre-cooling operation lasts for, for example, 30 minutes (Δt d1 ) Or, the process ends when all storage chambers reach a predetermined value (control S1-3).

[0057] In this embodiment, when the pre-cooling operation is completed, the refrigerator transitions to a refrigerant recovery operation before the defrosting operation (time td1 1. Control S1-4). In the refrigerant recovery operation, the three-way valve 101 opens the outlet 101a side, the compressor 24 and the evaporator fan 9 remain ON, the refrigerator compartment damper 20 opens, and the two-way valve 52c closes. By operating in this state, a part of the refrigerant in the evaporator 14, the gas-liquid separator 54, etc. is moved to the heat radiating part 50, specifically, between the check valve 130 and the two-way valve 52c. At this time, the reason for opening the refrigerator compartment damper 20 is to increase the heat exchange amount of the evaporator 14 by the return air from the refrigerator compartment 2, make it easier to evaporate the refrigerant in the evaporator 14, and improve the efficiency of the refrigerant recovery operation.

[0058] After performing this refrigerant recovery operation for, for example, 3 minutes (Δt d2 ), the defrosting operation is started (time t d2 , Control S1-5, Control S1-6).

[0059] In this defrosting operation, the compressor 24 remains ON, the two-way valve 52c remains closed, the three-way valve 101 opens the outlet 101b side (the outlet 101a side is closed), and the evaporator fan 9 is turned OFF. Thereby, the high-temperature gas from the compressor 24 shown in FIG. 4B heats the evaporator 14. At this time, since the two-way valve 52c is closed, the refrigerant from the check valve 130 or the three-way valve 101 to the two-way valve 52c, including the heat radiating part 50 and the dryer 51, is in a blocked state. The reason for this will be described later.

[0060] Here, one of the blocked portions of the flow path is the two-way valve 52c, but the other is not determined as the check valve 130 or the three-way valve 101. This is because when the pressure of the refrigerant in the three-way valve 101 is higher than the blocked refrigerant, a force acts in the direction from the three-way valve 101 toward the heat radiating part 50, that is, the same direction as the refrigerant flow during the cooling operation shown in FIG. 4A, etc., so the check valve 130 cannot block the refrigerant and the three-way valve 101 will block it. On the other hand, when the pressure of the blocked refrigerant is higher than the refrigerant in the three-way valve 101, a force from the heat radiating part 50 to the three-way valve 101, which is opposite to the cooling operation, acts, so the check valve 130 is blocked.

[0061] Continue this defrosting operation and the evaporator temperature T detected by the evaporator temperature sensor 40 df becomes the defrosting end temperature Tfin Reached (time t) d3 ) and the defrosting operation is terminated (control S1-7).

[0062] After the defrosting operation is completed, in this embodiment, before returning to normal cooling operation, the compressor 24 remains ON, the evaporator fan 9 remains OFF, the three-way valve 101 is opened on the outlet 101a side (the outlet 101b side is closed), and the two-way valve 52c is opened to perform evaporator cooling operation (control S1-8). The refrigeration cycle is the same as the cooling operation, but with the evaporator fan 9 OFF, i.e., airflow to storage chambers 2, 6, and 7 is suppressed, and the temperature of the evaporator 14 and the surrounding air is cooled. This operation prevents the air around the evaporator 14, which is hotter than the storage chambers 2, 6, and 7 immediately after the defrosting operation, from flowing into the storage chambers 2, 6, and 7 and unnecessarily heating the food inside.

[0063] After that, the evaporator cooling operation is performed for, for example, 5 minutes (Δt d3 After this, the cooling operation returns to cooling the storage chambers 2, 6, and 7 by blowing air around the evaporator 14 using the normal evaporator fan 9 (at time t d4 (Control S1-9, Control S1-10).

[0064] The above describes the basic control system for the defrosting operation of this refrigerator.

[0065] Next, we will describe the effects of the refrigerator in this embodiment.

[0066] In this embodiment, the defrosting operation of the refrigerator 1 is a hot gas defrosting method in which the evaporator 14 is heated by a high-temperature refrigerant discharged from the compressor 24 to melt the frost adhering to the evaporator 14, and the refrigerant that has heated the evaporator 14 returns to the compressor 24 via the gas-liquid separator 54.

[0067] Here, the liquid refrigerant condensed by heating the evaporator 14 cannot be contained within the gas-liquid separator 54 because there is no place for it to actively evaporate. It is possible that it will flow out into the suction pipe 57 and reach the compressor 24. When liquid refrigerant returns to the compressor 24, it is difficult to compress the refrigerant in its liquid state, and the compressor 24, which is designed to compress gaseous refrigerant, may be damaged, potentially causing damage to the piston or other components. This is called liquid return.

[0068] In contrast, the refrigerator 1 of this embodiment is equipped with a two-way valve 52c, and during defrosting operation, the two-way valve 52c is closed, thereby blocking the refrigerant from the check valve 130 or three-way valve 101 to the two-way valve 52c, including the heat dissipation section 50 and the dryer 51. That is, the refrigerant from the check valve 130 or three-way valve 101 to the two-way valve 52c does not circulate, so the defrosting operation is performed with a smaller amount of circulating refrigerant than the total amount of refrigerant sealed in the entire refrigeration cycle. As a result, even if the refrigerant condenses into liquid refrigerant in the evaporator 14 during defrosting operation, the amount will be within a range that can be contained in the gas-liquid separator 54, and liquid return to the compressor 24 can be suppressed. Furthermore, although this method adjusts the amount of refrigerant, there is no energy loss of the refrigerant between the compressor 24 and the evaporator 14, nor is there any energy consumption to vaporize the refrigerant from the evaporator 14 to the compressor 24.

[0069] As described above, the refrigerator 1 of this embodiment is equipped with a two-way valve 52c, and by closing the two-way valve 52c during defrosting operation, the refrigerant from the check valve 130 or three-way valve 101, including the heat dissipation section 50 and the dryer 51, to the two-way valve 52c is blocked, thereby providing a refrigerator that achieves highly efficient hot gas defrosting while suppressing liquid return from the compressor.

[0070] The pressure on the high-pressure side of the refrigeration cycle (the pressure on the discharge side of the compressor 24) basically depends on the condensation temperature of the refrigerant; a higher condensation temperature results in a higher pressure on the high-pressure side. During cooling operation, the refrigerant condenses by exchanging heat with the surrounding air (e.g., 25°C), which is hotter than the inside of the refrigerator, via the heat dissipation unit 50, so the condensation temperature is generally high (e.g., 28°C). During defrosting operation, the refrigerant, especially immediately after the start of defrosting operation, exchanges heat with the evaporator 14, which is at a low temperature (e.g., -20°C), so the condensation temperature is also low (e.g., 0°C). As a result, the pressure of the refrigerant on the high-pressure side during cooling operation is higher than that of the refrigerant during defrosting operation. Without the two-way valve 52c, this pressure difference would cause the refrigerant from the three-way valve 101 to the two-way valve 52c, including the heat dissipation unit 50 and the dryer 51, to flow into the refrigerant circulation path during defrosting operation (the area indicated by the arrow in Figure 4B) via the capillary tube 53c and the first branch junction 211. Therefore, without the two-way valve 52c, all of the sealed refrigerant becomes circulating refrigerant. Also, during cooling operation, the refrigerant condenses before reaching the capillary tube 53c, so a high-density liquid refrigerant is required downstream of the dryer 51 and heat dissipation unit 50, and liquid refrigerant is also required for evaporation in the evaporator 14. On the other hand, during defrosting operation, there is no place to store liquid refrigerant other than the liquid refrigerant condensed in the evaporator 14 and the gas-liquid separator 54, so if the amount of refrigerant in the refrigerant circulation path is the same as during cooling operation, the amount of refrigerant will basically be excessive, and there is a high possibility that it will return to the compressor 24 as liquid. Therefore, in the refrigerator of this embodiment, a portion of the refrigerant is blocked to suppress the amount of circulating refrigerant.

[0071] Furthermore, in order to implement the control that partially blocks the refrigerant as described above, a refrigerant control means such as a two-way valve 52c is necessary. By providing this two-way valve 52c, another effect mentioned above can also be obtained. Specifically, by closing the two-way valve 52c when the compressor 24 is turned OFF during cooling operation, the effect of improving energy saving performance during cooling operation can be obtained. Therefore, it is effective to provide the two-way valve 52c not only in defrosting operation but also in cooling operation.

[0072] Next, the effects of the refrigerant recovery operation in this embodiment will be explained. The refrigerator 1 in this embodiment is equipped with a refrigerant recovery operation (control S1-4 in Figure 5) in which the two-way valve 52c is closed while allowing refrigerant to flow from the three-way valve 101 to the outlet 101a. In this refrigerant recovery operation, because the two-way valve 52c is closed, the refrigerant drawn in from the evaporator 14 etc. and discharged from the compressor 24 collects upstream of the two-way valve 52c, specifically in the heat dissipation section 50 and the dryer 51. As a result, the amount of refrigerant that is blocked during defrosting operation (refrigerant from the check valve 130 or the three-way valve 101 to the two-way valve 52c) increases, and the amount of circulating refrigerant decreases. In other words, by performing the refrigerant recovery operation, the amount of circulating refrigerant is adjusted so that it stays within a range where liquid return does not occur.

[0073] Note that the time Δt used for the termination condition of the refrigerant recovery operation (control S1-5 in Figure 5) is also used. d2 When the rotational speed of the compressor 24 is high, the refrigerant recovery rate is high, so it is better to shorten the time compared to when the rotational speed is low. This can suppress excessive recovery. Also, in this embodiment, the end is determined by time, but the evaporator temperature T DF These could also be used as criteria for judgment.

[0074] Furthermore, although a refrigerant recovery operation is performed in this embodiment, if, for example, the amount of refrigerant that needs to be blocked is sufficient with the refrigerant from the check valve 130 to the two-way valve 52c during the cooling operation, the refrigerant recovery operation may be omitted, and the two-way valve 52c may be closed at the start of the defrosting operation. Also, as in the third embodiment described later, if it is desired to increase the amount of circulating refrigerant, such as when utilizing the refrigerant after it has passed through the evaporator 14, that is, to prevent too much refrigerant from being blocked during the defrosting operation, the two-way valve 52c may be opened at the beginning of the defrosting operation and then closed midway through.

[0075] Next, the effects of the check valve 130 in this embodiment will be explained. As mentioned above, the refrigerant on the high-pressure side during cooling operation is at a higher pressure than the refrigerant during defrosting operation, at least immediately after the start of defrosting operation. Therefore, during defrosting operation, the pressure inside the three-way valve 101, which is the refrigerant circulation path during defrosting operation, is lower than the pressure inside the three-way valve 101, which is the closed outlet 101a side of the three-way valve 101. As a result, a back pressure occurs at the outlet 101a (the pressure at the outlet is higher than the pressure inside the three-way valve 101, and a force is exerted from the outlet towards the inside of the valve). General electric valves have a low blocking capacity against back pressure, so when such back pressure occurs, it flows from the outlet 101a into the inside of the three-way valve 101, which is the refrigerant circulation path. In this case, if there is no check valve 130, the refrigerant from the outlet 101a of the three-way valve 101 to the two-way valve 52c may flow into the refrigerant circulation path through the inside of the three-way valve 101. However, by providing the check valve 130, the outflow of refrigerant downstream of the check valve 130 (from the check valve 130 to the two-way valve 52c) can be suppressed. On the other hand, if the three-way valve 101 is resistant to back pressure and can withstand the back pressure generated during defrosting operation, or if there is little refrigerant outflow due to back pressure, the three-way valve 101 may be omitted.

[0076] In this embodiment, the refrigerator 1, as shown in Figure 3, etc., has a check valve 130 upstream of the heat dissipation section 50 and a two-way valve 52c immediately before the capillary tube 53c, and the range of the refrigerant flow path to be blocked during defrosting operation is from the check valve 130 (or three-way valve 101) to the two-way valve 52c, including the heat dissipation section 50 and the dryer 51. In other words, a relatively wide range of the refrigerant flow path that is not used as a refrigerant circulation flow path during defrosting operation (areas not indicated by arrows in Figure 4B) can be blocked. On the other hand, the range to be blocked only needs to be such that the amount of refrigerant in the refrigerant circulation flow path during defrosting operation can be adjusted to an appropriate range. For example, if the amount of circulating refrigerant can be adjusted to an appropriate amount by blocking the refrigerant that can be sealed in the condensation prevention pipe 50c, then a check valve 130 may be provided between the wall heat dissipation pipe 50b and the condensation prevention pipe 50c, and a two-way valve 52c may be provided between the condensation prevention pipe 50c and the dryer 51, so that only the condensation prevention pipe 50c can be blocked. On the other hand, if the refrigerant flow path to be blocked is narrow and the blocked flow path is filled with liquid refrigerant, a condition called liquid seal occurs, where the volume change due to pressure changes is large and there is a risk of damaging the refrigerant piping. Therefore, it is desirable that the internal volume of the refrigerant flow path to be blocked be larger than the volume when all the refrigerant sealed in the refrigeration cycle is in a liquid state, and at least it must be larger than the volume when all the refrigerant to be blocked is in a liquid state. Accordingly, in the refrigerator 1 of this embodiment, the check valve 130 is provided upstream of the heat dissipation section 50, and the two-way valve 52c is provided immediately before the capillary tube 53c, so that a relatively wide range of refrigerant flow paths can be blocked. Note that the specific volume of liquid refrigerant changes with temperature, and the specific volume increases as the temperature rises. Therefore, it is best to calculate using the liquid refrigerant density at the maximum expected condensation temperature (for example, 50°C).

[0077] [Second Example] Figure 7 is a schematic diagram showing the configuration of the refrigeration cycle 202 of the refrigerator 1 of the second embodiment. The refrigeration cycle 201 of the first embodiment (Figure 3) has one means for reducing the pressure of the refrigerant (capillary tube 53c) and also has one refrigerant flow path during cooling operation. In contrast, the refrigeration cycle 202 of the second embodiment shown in Figure 7 (Figure 7) is equipped with two capillary tubes 53, a first capillary tube 53a and a second capillary tube 53b, which are arranged in parallel, and a three-way valve 52 is provided to switch between them, while the two-way valve 52c is omitted.

[0078] The three-way valve 52 has two outlets, indicated by 52a and 52b, and is a component that can switch which outlet the refrigerant flows through, and can also be set to a fully closed state so that neither outlet 52a nor outlet 52b allows refrigerant to flow. In addition, the three-way valve 52 in this embodiment can also be set to a double-open state so that refrigerant flows through either outlet. Outlet 52a of the three-way valve 52 is connected to the first capillary tube 53a via refrigerant piping, and outlet 52b is connected to the second capillary tube 53b via refrigerant piping.

[0079] In the refrigerator 1 of the second embodiment, during the cooling operation performed with the outlet 101a of the three-way valve 101 open, there are cases where the first capillary tube 53a is used and cases where the second capillary tube 53b is used, and the refrigerant flow path is different in each case.

[0080] When using the first capillary tube 53a, the outlet 52a of the three-way valve 52 is opened. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 24 passes through the outlet 101a of the three-way valve 101, then flows through the heat dissipation section 50 and the dryer 51, and finally reaches the three-way valve 52. After passing through the outlet 52a of the three-way valve 52, the refrigerant is depressurized in the first capillary tube 53a, becoming a low-temperature, low-pressure gas-liquid two-phase refrigerant, and then reaches the evaporator 14 via the second branch junction 212 and the first branch junction 211. The subsequent refrigerant flow is the same as in the first embodiment and is therefore omitted.

[0081] When using the second capillary tube 53b, the outlet 52b of the three-way valve 52 is opened. The refrigerant flow path from the compressor 24 to the three-way valve 52 is the same. The refrigerant that reaches the three-way valve 52 passes through the outlet 52b of the three-way valve 52, is depressurized in the second capillary tube 53b, becomes a low-temperature, low-pressure gas-liquid two-phase refrigerant, and then reaches the evaporator 14 via the second branch junction 212 and the first branch junction 211.

[0082] Thus, in the refrigerator 1 of the second embodiment, the control of the two refrigerant flow paths during cooling operation is performed by the three-way valve 52. The three-way valve 52 in this embodiment can be fully closed. This makes it possible to perform the same blocking control as the two-way valve 52c in the first embodiment.

[0083] In other words, if a refrigerant control means that switches between multiple pressure reducing means, as in this embodiment, is equipped with a fully closed control that can block any of the flow paths, then control using the two-way valve 52c of the first embodiment can be implemented. In addition, compared to a refrigerator equipped with multiple pressure reducing means, as in this embodiment, which is controlled by a three-way valve, the effects shown in the first embodiment can be obtained without the cost and space associated with installing the two-way valve 52c, thus improving cost performance and space efficiency.

[0084] Although the control of the refrigerant flow path during cooling operation is not related to the effects described above, here is an example of refrigerant flow path control during cooling operation. The first capillary tube 53a is a capillary tube with a weaker restriction (lower flow resistance) than the second capillary tube 53b. Under conditions where the temperature inside the refrigerator is relatively high, such as immediately after powering on the refrigerator 1 or when high-temperature food is placed in the storage compartment, and the rotation speed of the compressor 24 is also relatively high, the first capillary tube 53a with a weaker restriction is used. Because the flow resistance is low, the amount of refrigerant circulated per unit time is large, and high cooling performance can be ensured. On the other hand, when the inside of the refrigerator is cool and stable, by using the second capillary tube 53b with a stronger restriction, it is possible to easily generate low-pressure refrigerant, i.e., low-temperature refrigerant, even under conditions where the rotation speed of the compressor 24 is low and power consumption is low, and low temperatures can be maintained in an energy-saving manner.

[0085] [Third Embodiment] Figure 8 is a cross-sectional view of the refrigerator of the third embodiment, corresponding to Figure 2 of the first embodiment. The front view of the refrigerator of the third embodiment is the same as that of Figure 1.

[0086] The refrigerator 1 of the third embodiment has the functions of performing refrigeration cooling operation, freezing cooling operation, and defrosting operation. Refrigeration cooling operation is an operation in which a low-temperature, low-pressure refrigerant passing through the first capillary tube 53a evaporates in the refrigeration evaporator 14a to cool a storage compartment in the refrigeration temperature range (e.g., refrigerator compartment 2). Freezing cooling operation is an operation in which at least one or more storage compartments in the freezing temperature range (e.g., freezer compartment 7) is cooled by the freezing evaporator 14b. Defrosting operation is an operation in which frost adhering to the freezing evaporator 14b is removed.

[0087] In the third embodiment of the refrigerator 1, a refrigerator evaporator compartment 8a is provided near the rear of the refrigerator compartment 2 to house a refrigerator evaporator 14a. The refrigerator evaporator compartment 8a is formed by a refrigerator compartment air passage component 61 and an inner box 10b, both located near the rear of the refrigerator compartment 2. The air in the refrigerator evaporator compartment 8a, which has been cooled by heat exchange with the refrigerator evaporator 14a, is blown into the refrigerator compartment 2 via the refrigerator compartment air passage 11 through a refrigerator compartment discharge port 11a provided in the refrigerator compartment air passage component 61 by a refrigerator fan 9a located above the refrigerator evaporator 14a, thereby cooling the inside of the refrigerator compartment 2. The air blown into the refrigerator compartment 2 returns to the refrigerator evaporator compartment 8a through a refrigerator compartment return port 15a provided in the refrigerator compartment air passage component 61 and is cooled again by the refrigerator evaporator 14a.

[0088] In the third embodiment of the refrigerator 1, a freezer evaporator compartment 8b is provided near the rear of the freezer compartment 7 to house a freezer evaporator 14b. The freezer evaporator compartment 8b is composed of a freezer air passage component 62 and an inner box 10b, both located near the rear of the freezer compartment 7. The air in the freezer evaporator compartment 8b, which has been cooled by heat exchange with the freezer evaporator 14b, is blown into the freezer compartment 7 through the freezer air passage 12 by a freezer fan 9b located above the freezer evaporator 14b, and then through the freezer discharge port 12a provided in the freezer air passage component 62, thereby cooling the inside of the freezer compartment 7. The air blown into the freezer compartment 7 returns to the freezer evaporator compartment 8b through the freezer return port 17 provided in the freezer air passage component 62, and is cooled again by the freezer evaporator 14b.

[0089] In the refrigerator 1 of the third embodiment, the vegetable compartment 6 is also cooled with air cooled by the freezer evaporator 14b. The air in the freezer evaporator compartment 8b, cooled by the freezer evaporator 14b, is blown into the vegetable compartment 6 by the freezer fan 9b via a vegetable compartment air passage (not shown) and a vegetable compartment damper (not shown), cooling the inside of the vegetable compartment 6. Although the cold air generated by the freezer evaporator 14b is blown into the vegetable compartment 6, the cold air is prevented from directly entering the vegetable compartment container 6b where food is stored, thereby suppressing drying of vegetables. When the vegetable compartment 6 is cold, the cooling of the vegetable compartment 6 is suppressed by closing the vegetable compartment damper. The air blown into the vegetable compartment 6 returns to the bottom of the freezer evaporator 14b via the vegetable compartment cold air return air passage 18, which is located at the bottom of the insulated partition wall 29.

[0090] When the door is opened or closed, moisture-laden air flows into the refrigerator compartment and enters the refrigerator compartment return port 15a, the freezer compartment return port 17, and the vegetable compartment cold air return duct 18, into the low-temperature refrigerator evaporator 14a and freezer evaporator 14b. As a result, moisture in the air condenses on the surfaces of each evaporator 14a and 14b and adheres as frost. As the frost grows, it hinders heat exchange between the evaporator and the air, and the airflow through the evaporator decreases due to the airflow resistance caused by the frost. Therefore, the refrigerator 1 performs a defrosting operation to melt the frost on each evaporator 14a and 14b.

[0091] The defrost water (melted water) generated during defrosting of the refrigeration evaporator 14b falls into the refrigeration chamber drain 23b located at the bottom of the refrigeration evaporator chamber 8b, and is discharged through the refrigeration chamber drain port 22b and the refrigeration chamber drain pipe 27b to the evaporation tray 32 located above the compressor 24 in the machine room 39.

[0092] The refrigerator evaporator 14a defrosts by off-cycle defrosting, which circulates air from the refrigerator compartment 2 to the refrigerator evaporator 14a and defrosts it using the heat from the refrigerator compartment 2. The defrost water generated during the defrosting of the refrigerator evaporator 14a falls into the refrigerator compartment drain 23a located at the bottom of the refrigerator evaporator compartment 8a and is discharged to the evaporation tray 32 in the machine room 39 via the refrigerator compartment drain (not shown) and the refrigerator compartment drain pipe (not shown).

[0093] A refrigerator temperature sensor 41, a freezer temperature sensor 42, and a vegetable compartment temperature sensor 43 are provided on the rear side of the interior of the refrigerator compartment 2, freezer compartment 7, and vegetable compartment 6, respectively. A refrigerator evaporator temperature sensor 40a is provided above the refrigerator evaporator 14a, and a freezer evaporator temperature sensor 40b is provided above the freezer evaporator 14b. These sensors detect the temperatures of the refrigerator compartment 2, freezer compartment 7, vegetable compartment 6, refrigerator evaporator 14a, and freezer evaporator 14b.

[0094] <Configuration and operation of the refrigeration cycle (refrigerant flow path) 200 in refrigerator 1> The configuration and operation of the refrigeration cycle (refrigerant flow path) 200 in refrigerator 1 will be described below with reference to Figures 9 and 10A to 10C. Figure 9 is a schematic diagram showing the configuration of the refrigeration cycle 200 in refrigerator 1 of the third embodiment. Figure 10A is an explanatory diagram showing the flow of refrigerant during refrigeration operation in refrigerator 1. Figure 10B is an explanatory diagram showing the flow of refrigerant during freezing operation in refrigerator 1. Figure 10C is an explanatory diagram showing the flow of refrigerant during defrosting operation in refrigerator 1.

[0095] As shown in Figure 9, the refrigerator 1 is equipped with a compressor 24, a heat dissipation unit 50, a dryer 51, a three-way valve 52, a capillary tube 53, a refrigerating evaporator 14a, a freezing evaporator 14b, a refrigerating gas-liquid separator 54a, a freezing gas-liquid separator 54b, and a check valve 55. The refrigerator 1 is also equipped with a three-way valve 101, a two-way valve 112, a defrosting capillary tube 103, and a check valve 104.

[0096] The refrigerator evaporator 14a is a component that absorbs heat from the refrigerator compartment 2 by exchanging heat between the refrigerant and the air inside the refrigerator compartment 2. The freezer evaporator 14b is a component that absorbs heat from the freezer compartment 7 (and vegetable compartment 6) by exchanging heat between the refrigerant and the air inside the freezer compartment 7.

[0097] The refrigeration gas-liquid separator 54a and the freezing gas-liquid separator 54b are components that separate liquid refrigerant and gaseous refrigerant, similar to the gas-liquid separator 54 in the first and second embodiments, and suppress the flow of liquid refrigerant to the compressor 24.

[0098] The three-way valve 52, like in the second embodiment, has two outlets, indicated by 52a and 52b, and is a component that can switch which outlet the refrigerant flows through, and can also be set to a fully closed state so that neither outlet 52a nor outlet 52b allows refrigerant to flow. In addition, the three-way valve 52 in this embodiment can also be set to a double-open state so that refrigerant flows through either outlet. Outlet 52a of the three-way valve 52 is connected to the first capillary tube 53a via refrigerant piping, and outlet 52b is connected to the second capillary tube 53b via refrigerant piping.

[0099] In the third embodiment, the first capillary tube 53a reduces the pressure of the refrigerant flowing to the refrigeration evaporator 14a side, and the second capillary tube 53b reduces the pressure of the refrigerant flowing to the freezing evaporator 14b side.

[0100] In the refrigerator 1 of the third embodiment, the first capillary tube 53a, the second capillary tube 53b, and the defrosting capillary tube 103 are soldered to the suction pipe 57. By fixing the connection with metal components through soldering, the refrigerator 1 improves its heat exchange efficiency. In the internal heat exchange section 58, it is sufficient that the first capillary tube 53a, the second capillary tube 53b, the defrosting capillary tube 103, and the suction pipe 57 are in close proximity to each other and can exchange heat.

[0101] Furthermore, for reasons to be explained later, the flow resistance of the defrosting capillary tube 103, which reduces the refrigerant pressure during defrosting operation, is set to be smaller than the flow resistance of the first capillary tube 53a and the second capillary tube 53b, which reduce the refrigerant pressure during cooling operation. Note that the flow resistance of the first capillary tube 53a is smaller than the flow resistance of the second capillary tube 53b.

[0102] In this third embodiment of the refrigerator 1, in the cooling operation performed with the outlet 101a of the three-way valve 101 open, there is a refrigeration cooling operation using the first capillary tube 53a and a freezing cooling operation using the second capillary tube 53b, and the refrigerant flow path is different for each.

[0103] Figure 10A shows the refrigerant flow during refrigeration operation. During refrigeration operation, the three-way valve 52 opens its outlet 52a. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 24 passes through the outlet 101a of the three-way valve 101, then flows through the heat dissipation section 50 and the dryer 51, and finally reaches the three-way valve 52. After passing through the outlet 52a of the three-way valve 52, the refrigerant is depressurized in the first capillary tube 53a, becoming a low-temperature, low-pressure gas-liquid two-phase refrigerant, and then reaches the refrigeration evaporator 14a via the third branch junction 105. After that, it returns to the compressor 24 via the refrigeration gas-liquid separator 54a, the fourth branch junction 56, and the suction pipe 57.

[0104] Figure 10B shows the flow of the refrigeration cooling operation. During refrigeration cooling operation, the three-way valve 52 opens its outlet 52b. The refrigerant flow path is the same from the compressor 24 to the three-way valve 52. The refrigerant that reaches the three-way valve 52 passes through the outlet 52b of the three-way valve 52, is depressurized in the second capillary tube 53b, becomes a low-temperature, low-pressure gas-liquid two-phase refrigerant, and then reaches the refrigeration evaporator 14b via the fifth branch junction 110. After that, it returns to the compressor 24 via the refrigeration gas-liquid separator 54b, the sixth branch junction 111, the fourth branch junction 56, and the suction pipe 57.

[0105] Thus, in the refrigerator 1 of the third embodiment, the three-way valve 52 switches between refrigeration operation and freezing operation.

[0106] Furthermore, this refrigerator 1 is equipped with a defrosting operation similar to that of the first embodiment.

[0107] Figure 10C shows the refrigerant flow during defrosting operation. In the defrosting operation of the third embodiment, the three-way valve 101 opens the outlet 101b on the first defrosting refrigerant flow path 59 side and closes the outlet 101a, while the two-way valve 112 is closed. The three-way valve 52 is basically completely closed (both outlets 52a and 52b are closed), and, similar to the two-way valve 52c in the first embodiment, the refrigerant from the check valve 130 or the three-way valve 101 to the three-way valve 52 is blocked. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 24 passes through the outlet 101b of the three-way valve 101 and then reaches the sixth branch junction 111 via the first defrosting refrigerant flow path 59. Since the two-way valve 112 is closed, the refrigerant that reaches the sixth branch junction 111 flows to the refrigeration evaporator 14b via the refrigeration gas-liquid separator 54b and performs heat exchange with the refrigeration evaporator 14b. As a result, the high-temperature, high-pressure refrigerant in the refrigeration evaporator 14b releases heat, heating the refrigeration evaporator 14b. The refrigerant that reaches the refrigeration evaporator 14b cools down and liquefies due to this heat release. The liquefied refrigerant passes through the defrosting capillary tube 103 via the fifth branch junction 110 and the second defrosting refrigerant flow path 59b. At this time, the refrigerant is depressurized by the defrosting capillary tube 103 and becomes a low-temperature, low-pressure gas-liquid two-phase refrigerant. The low-temperature, low-pressure refrigerant passes through the check valve 104 and then reaches the inlet of the refrigerator evaporator 14a via the third branch junction 105. The low-temperature refrigerator evaporator 14a exchanges heat with the surrounding air. As a result, the surrounding air of the refrigerator evaporator 14a becomes cold. The cold surrounding air of the refrigerator evaporator 14a is sent to the refrigerator compartment 2 (Figure 8) by the refrigerator fan 9a. As a result, refrigerator 1 cools the refrigerator compartment 2. Through this heat exchange, the refrigerant in the refrigerator evaporator 14a absorbs heat from the air in the refrigerator compartment 2, increasing its enthalpy and dryness, becoming a nearly saturated gaseous refrigerant. The refrigerant then reaches the outlet of the refrigerator evaporator 14a, passes through the refrigerator gas-liquid separator 54a and the fourth branch junction 56, and reaches the suction pipe 57. After that, the refrigerant flows through the suction pipe 57 and returns to the compressor 24.

[0108] The flow of refrigerant from the third branch junction 105 to the compressor 24 during defrosting operation is the same as in refrigeration cooling operation (Figure 10A). However, in cooling operation, the refrigerant in the suction pipe 57 mainly exchanges heat with the refrigerant in the first capillary tube 53a via the internal heat exchange section 58, whereas during defrosting operation, the refrigerant in the suction pipe 57 mainly exchanges heat with the refrigerant in the defrosting capillary tube 103 via the internal heat exchange section 58.

[0109] Here, we compare the defrosting operation of the third embodiment with that of the first embodiment.

[0110] In the refrigerator 1 of the third embodiment, the high-temperature refrigerant discharged from the compressor 24 heats the refrigeration evaporator 14b, and then exchanges heat with the air surrounding the refrigeration evaporator 14a (refrigerator compartment 2 and refrigeration evaporator compartment 8a) in the refrigeration evaporator 14a. This cools the refrigeration compartment 2, and the absorbed heat is used for heat dissipation in the refrigeration cycle, thus being used to heat the refrigeration evaporator 14b. Therefore, the power consumption of the compressor 24 required for defrosting the refrigeration evaporator 14b is reduced, and furthermore, the refrigeration compartment 2 is cooled during defrosting, reducing the cooling load after the defrosting operation. As a result, the defrosting operation is more energy-efficient than the defrosting operation of the first embodiment, which does not absorb heat in the refrigeration evaporator 14b. In addition, because the refrigerant inside the refrigeration evaporator 14a vaporizes due to the heat absorbed by the refrigeration evaporator 14a, the defrosting operation of the third embodiment described above is less prone to liquid return to the compressor 24 compared to the defrosting operation of the first embodiment.

[0111] Furthermore, in the defrosting operation of the refrigerator 1 of the third embodiment, the refrigerant in the suction pipe 57 exchanges heat mainly with the refrigerant in the defrosting capillary tube 103 via the internal heat exchange section 58. Due to this heat exchange, the refrigerant in the suction pipe 57 is also heated, and if there is liquid refrigerant, it vaporizes. Therefore, compared to the defrosting operation of the first embodiment, where there is no high-pressure refrigerant to exchange heat with the suction pipe 57 during defrosting, it is less likely for liquid refrigerant to return to the compressor 24.

[0112] As described above, the refrigerator 1 of the third embodiment has a refrigeration cycle that is less prone to liquid backflow than the refrigerator 1 of the first embodiment.

[0113] On the other hand, in the refrigerator 1 of the third embodiment, it is also effective to close the three-way valve 52 during defrosting operation to block the refrigerant from the check valve 130 or three-way valve 101 to the three-way valve 52, including the heat dissipation section 50 and the dryer 51, thereby reducing the amount of circulating refrigerant during defrosting operation. The reasons why liquid backflow is likely to occur even during defrosting operation in the refrigerator 1 of the third embodiment and the effects obtained by closing the three-way valve 52 during defrosting operation to reduce the amount of circulating refrigerant during defrosting operation will be explained below.

[0114] During refrigeration operation as shown in Figure 10A, the heat dissipation unit 50 (three heat radiators) is used as the heat dissipation means, whereas during defrosting operation as shown in Figure 10C, the only heat dissipation means is the refrigeration evaporator 14b. For this reason, the refrigerant flow path on the heat dissipation side is shorter and the amount of refrigerant on the heat dissipation side tends to be less during defrosting operation. On the other hand, since the refrigerant flow path on the evaporation side is basically the same, if the amount of circulating refrigerant is the same, the amount of refrigerant tends to be excessive and liquid backflow is likely to occur. For this reason, during defrosting operation, the three-way valve 52 is closed to block the refrigerant from the check valve 130 or three-way valve 101 to the three-way valve 52, including the heat dissipation unit 50 and the dryer 51, thereby reducing the amount of circulating refrigerant during defrosting operation and suppressing liquid backflow.

[0115] Furthermore, in the refrigeration cooling operation shown in Figure 10A and the defrosting operation shown in Figure 10C, the points where the refrigerant is significantly reduced in pressure, that is, where it is greatly affected by flow resistance, are the first capillary tube 53a in the refrigeration cooling operation and the defrosting capillary tube 103 in the defrosting operation, respectively. As mentioned above, the flow resistance of the defrosting capillary tube 103, which reduces the refrigerant pressure in the defrosting operation, is set to be smaller than the flow resistance of the first capillary tube 53a, which reduces the refrigerant pressure in the cooling operation. The reason for this is that in the refrigeration cooling operation, heat is dissipated by exchanging heat with the relatively high-temperature outside air via the heat dissipation section 50, whereas in the defrosting operation, heat is dissipated by exchanging heat with the refrigeration evaporator 14b, which is basically below freezing point until the frost melts, so the condensation temperature tends to be low, that is, the condensation pressure tends to be low. On the other hand, the conditions required for the evaporation side (heat exchange between the refrigerating evaporator 14a and the refrigerator compartment 2 via the refrigerating evaporator chamber 8a) are basically the same for both refrigeration cooling and defrosting operations. Therefore, it is preferable to suppress pressure reduction during defrosting, where the condensation pressure is lower, and to make the evaporation pressure the same for both refrigeration cooling and defrosting operations. Furthermore, by suppressing the amount of pressure reduction and reducing the pressure difference between condensation pressure and evaporation pressure, the ratio of heat dissipation and heat absorption to the power consumption of the compressor 24 increases. In other words, both the heating efficiency of the refrigeration evaporator 14b and the cooling efficiency of the refrigerating evaporator 14a increase. For this reason, the flow resistance of the defrosting capillary tube 103 is set to be lower than the flow resistance of the first capillary tube 53a, so that pressure reduction is less likely to occur during defrosting than during refrigeration cooling.

[0116] On the other hand, if the flow resistance of the defrosting capillary tube 103, which is a means of reducing pressure in the refrigeration cycle, is small, the subcooling is small and the amount of liquid refrigerant on the heat dissipation side tends to be small. Therefore, if the amount of circulating refrigerant is the same, the amount of refrigerant evaporated is greater in defrosting operation than in refrigeration cooling operation, meaning that liquid return is more likely to occur. However, in the refrigerator 1 of the third embodiment, the three-way valve 52 is closed during defrosting operation to reduce the amount of circulating refrigerant during defrosting operation, thereby suppressing liquid return.

[0117] Furthermore, a detailed explanation will be omitted as this is a general feature of a two-evaporator system equipped with both refrigeration and freezing operations. However, during refrigeration operation, the evaporation temperature is higher than that of the freezer compartment 7. In this case, the refrigerant in the freezing evaporator 14b (more precisely, the refrigerant in the refrigerant piping between the outlet 52b of the three-way valve 52 and the check valve 55) is blocked and does not circulate. Therefore, it is common to design the system assuming that the amount of circulating refrigerant is less during refrigeration operation than during freezing operation. On the other hand, during defrosting operation, if the three-way valve 52 is not blocked, the sealed refrigerant becomes circulating refrigerant. Therefore, more circulating refrigerant is available during defrosting operation than during refrigeration operation, making liquid return more likely. However, by blocking the three-way valve 52 during defrosting operation, the amount of circulating refrigerant during defrosting operation is reduced, thereby suppressing liquid return.

[0118] In summary, compared to the refrigeration operation shown in Figure 10A, the defrosting operation shown in Figure 10C is more prone to liquid backflow than the refrigeration operation because the refrigerant piping length of the heat dissipation means is shorter, the flow resistance of the defrosting capillary tube 103 is smaller than that of the first capillary tube 53a, and the amount of circulating refrigerant increases when the three-way valve 52 is not blocked. However, by blocking the three-way valve 52 during the defrosting operation, the refrigerant from the check valve 130 or three-way valve 101 to the three-way valve 52, including the heat dissipation unit 50 and the dryer 51, is blocked, thereby reducing the amount of circulating refrigerant during the defrosting operation and suppressing liquid backflow.

[0119] Furthermore, compared to the refrigeration cooling operation shown in Figure 10B, the defrosting operation shown in Figure 10C has the same amount of circulating refrigerant when the three-way valve 52 is not blocked, but the refrigerant piping length of the heat dissipation means is shorter, and the flow resistance of the defrosting capillary tube 103 is smaller than that of the second capillary tube 53b, which are common to both refrigeration cooling and defrosting operations. In other words, if the three-way valve 52 is not blocked, liquid backflow is likely to occur. In addition, as mentioned above, in order to raise the evaporation temperature of the refrigeration cooling operation compared to the freezer compartment 7 cooled by the refrigeration cooling operation, the flow resistance of the first capillary tube 53a, which is generally used in refrigeration cooling operations, is smaller than that of the second capillary tube 53b. Therefore, the relationship of flow resistance is "defrosting capillary tube 103 < first capillary tube 53a < second capillary tube 53b". The difference in the pressure reduction means (capillary tubes) between refrigeration cooling and defrosting operations is greater than the difference in the pressure reduction means (capillary tubes) between refrigeration cooling and defrosting operations, meaning that the effect of the difference in flow resistance is greater than in refrigeration cooling operations. Therefore, compared to refrigeration operation, defrosting operation is more prone to liquid backflow. Thus, it is effective to suppress liquid backflow by blocking the three-way valve 52 during defrosting operation, thereby blocking the refrigerant flow from the check valve 130 or three-way valve 101 to the three-way valve 52, including the heat dissipation section 50 and the dryer 51, and reducing the amount of refrigerant that can be circulated during defrosting operation.

[0120] In addition, regarding another issue in the defrosting operation of the third embodiment, when heat is absorbed by the refrigerator evaporator 14a, closing the three-way valve 52 during the defrosting operation is also effective.

[0121] If the refrigerator compartment 2, which is in the refrigeration temperature range, is cooled excessively, there is a risk that food will freeze. On the other hand, in the defrosting operation of the third embodiment, the refrigeration cycle involves heat absorption by the refrigerator evaporator 14a, so suppressing excessive cooling (heat absorption) under certain conditions becomes a challenge. For example, if the ambient temperature around the refrigerator 1 (temperature detected by the outside air temperature sensor 37a) is low, more specifically, if it is lower than the temperature assumed to be the living environment of the refrigerator 1 (18°C or higher), the amount of cooling required to maintain the temperature of the refrigerator compartment 2 is small. In such cases, if heat absorption occurs in the refrigerator evaporator 14a during defrosting, excessive cooling is likely to occur, and suppressing this becomes a challenge.

[0122] In response to this, two solutions are conceivable, but in either case, it is effective to block the three-way valve 52 during the defrosting operation, thereby blocking the refrigerant from the check valve 130 or three-way valve 101 to the three-way valve 52, including the heat dissipation section 50 and the dryer 51, and reducing the amount of refrigerant that can be circulated during the defrosting operation.

[0123] First, as a solution, to suppress excessive cooling during defrosting, the refrigerator fan 9a is stopped or its rotation speed is reduced. This suppresses heat exchange between the refrigerator evaporator 14a and the refrigerator compartment 2 (more precisely, the refrigerator evaporator compartment 8a), that is, it suppresses heat absorption in the refrigerator evaporator 14a, and thus suppresses excessive cooling of the refrigerator compartment 2. On the other hand, suppressing heat absorption in the refrigerator evaporator 14a makes it difficult for the refrigerant to vaporize, so if the amount of refrigerant is large, it is likely that it will not vaporize completely and liquid return will occur. To address this, during defrosting, the three-way valve 52 is closed, blocking the refrigerant from the check valve 130 or three-way valve 101 to the three-way valve 52, including the heat dissipation section 50 and the dryer 51, thereby reducing the amount of refrigerant that can be circulated during defrosting and suppressing liquid return.

[0124] The second solution involves blocking the three-way valve 52 to block the refrigerant from the check valve 130 or three-way valve 101 to the three-way valve 52, including the heat dissipation section 50 and the dryer 51, and further increasing the amount of refrigerant that is blocked, thereby excessively reducing the amount of refrigerant that can be circulated during defrosting operation, and causing the liquid to run out relatively upstream of the refrigerator evaporator 14a (causing all of the refrigerant to gasify). When the liquid runs out and the refrigerant can no longer evaporate, almost no heat absorption can occur in the refrigerator evaporator 14a, thus suppressing excessive cooling of the refrigerator compartment 2.

[0125] Here, as a method to increase the amount of refrigerant that is blocked by the three-way valve 52 during defrosting, as in the second solution, the refrigerant recovery operation described in the first embodiment (an operation in which the three-way valve 101 is opened on the outlet 101a side and the three-way valve 52 is fully closed before the defrosting operation and the compressor 24 is operated) is effective. The amount of refrigerant that is blocked can be adjusted by adjusting whether or not this refrigerant recovery is performed and the time. Therefore, as a specific control to suppress excessive cooling of the refrigerator compartment 2 in the second solution, in order to increase the amount of refrigerant that is blocked, refrigerant recovery is performed before the defrosting operation and the time of this refrigerant recovery is made relatively long.

[0126] Alternatively, the three-way valve 52 may be fully closed at the start of the defrosting operation without performing a refrigerant recovery operation. In this case, the refrigerant between the outlet 101a and the three-way valve 52 is blocked during the cooling operation immediately preceding the start of the defrosting operation. Therefore, a larger amount of refrigerant can be circulated for the defrosting operation compared to when a refrigerant recovery operation is performed.

[0127] Furthermore, the three-way valve 52 may be fully closed after a predetermined time has elapsed since the start of the defrosting operation, without performing a refrigerant recovery operation. In this case, the amount of refrigerant between the three-way valve 52 and the outlet 101a will gradually decrease until the predetermined time has elapsed. By fully closing the three-way valve 52 after the predetermined time has elapsed, a certain amount of refrigerant between the outlet 101a and the three-way valve 52 is blocked, and the defrosting operation continues. As a result, the amount of refrigerant circulating during the defrosting operation is even greater compared to the case where the three-way valve 52 is fully closed at the start of the defrosting operation. In particular, in the refrigerator 1 of the third embodiment, when the temperature of the refrigerator compartment 2 (temperature detected by the refrigerator compartment temperature sensor 41) or / and the ambient temperature around the refrigerator 1 is high, compared to when the temperature of the refrigerator compartment 2 or / and the ambient temperature around the refrigerator 1 is low, the predetermined time from the start of the defrosting operation until the three-way valve 52 is fully closed is increased, reducing the amount of refrigerant that is blocked during the defrosting operation and increasing the amount of refrigerant that can be circulated during the defrosting operation. This increases the amount of heat that the refrigerant can absorb in the refrigerator evaporator 14a, aiming to increase the amount of cooling in the refrigerator compartment 2 and improve the defrosting efficiency of the freezing evaporator 14b due to the increase in energy. Thus, under conditions where there is little concern about excessive cooling of the refrigerator compartment 2, it is effective to increase the amount of circulating refrigerant within the range where liquid return does not occur to promote heat absorption in the refrigerator evaporator 14a. When increasing the amount of circulating refrigerant to promote heat absorption in the refrigerator evaporator 14a, it is effective to increase the rotation speed of the refrigerator fan 9a. A higher rotation speed of the refrigeration fan 9a promotes heat exchange between the refrigeration evaporator 14a and the refrigerator compartment 2 (more precisely, the refrigeration evaporator compartment 8a), making it easier for the refrigerant to vaporize. This is effective in both suppressing liquid return and promoting heat absorption. The predetermined time is determined so that the amount of refrigerant circulating during the defrosting operation corresponds to the amount of heat absorbed by the refrigeration evaporator 14a.

[0128] Here, ignoring thermal losses, in the defrosting operation of the third embodiment, the amount of heat generated by the refrigeration evaporator 14b (heat dissipation of the refrigeration cycle) is the sum of the amount of heat absorbed by the refrigerating evaporator 14a (heat absorbed of the refrigeration cycle) and the energy added by the compressor 24. Since both of the means for suppressing excessive cooling of the two refrigerator compartments 2 described above involve suppressing the amount of heat absorbed by the refrigerating evaporator 14a, suppressing the amount of heat absorbed by the refrigerating evaporator 14a also reduces the amount of heat generated by the refrigeration evaporator 14b. To counteract this, it is effective to increase the rotational speed of the compressor 24 and increase the energy added by the compressor 24.

[0129] To increase the energy added by the compressor 24, the energy released to the outside by the compressor 24 may be suppressed by stopping the machine room fan 38, setting the rotation speed of the machine room fan 38 to a lower speed than when excessive cooling is suppressed, or setting the rotation speed of the machine room fan 38 to a lower speed than when refrigeration cooling is in operation. By suppressing the energy released to the outside, the energy consumed by the compressor 24 can more easily reach the refrigeration evaporator 14b (heat loss is reduced), and an increase in the energy added by the compressor 24 to the refrigeration evaporator 14b can be expected. This is particularly effective under conditions where the amount of heat absorbed in the refrigeration evaporator 14a, where the energy added by the compressor 24 is important, is suppressed.

[0130] The above describes the defrosting operation in the refrigerator 1 of the third embodiment, and the effects of adjusting the amount of refrigerant that can be circulated using the three-way valve 52 during the defrosting operation.

[0131] It should be noted that the features shown in this embodiment are not limited to the refrigeration cycle shown in Figures 9 and 10A-C, but are common to any configuration that includes a defrosting operation in which the refrigeration evaporator 14b is heated to remove frost by a refrigeration cycle in which heat is absorbed by the refrigeration evaporator 14a and heat is released by the refrigeration evaporator 14b.

[0132] For example, this is also effective in the modified example 1 and modified example 2 of the third embodiment shown in Figures 11 and 12.

[0133] [Example 1] Figure 11 is a schematic diagram showing the refrigeration cycle 200a of Modification Example 1 of the third embodiment.

[0134] In this modified example, a defrosting refrigerant pipe 301 is provided that flows only during defrosting operation and exchanges heat with the refrigeration evaporator 14b, and during defrosting operation, the refrigeration evaporator 14b is heated by this defrosting refrigerant pipe 301.

[0135] The refrigerant flow during the defrosting operation of this modified example will be explained. The cooling operation is the same as in the third embodiment and will therefore be omitted. During the defrosting operation, the compressor 24 is driven by opening the outlet 101b side of the three-way valve 101. As a result, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 24 passes through the outlet 101b of the three-way valve 101, then flows through the first defrosting refrigerant flow path 59 to the defrosting refrigerant piping 301 which exchanges heat with the refrigeration evaporator 14b, heating the refrigeration evaporator 14b. After that, the refrigerant in the defrosting refrigerant piping 301 that has dissipated heat in the refrigeration evaporator 14b flows through the second defrosting refrigerant flow path 59b and the defrosting capillary tube 103 to the refrigeration evaporator 14a, where it absorbs heat, and then returns to the compressor 24 via the refrigeration gas-liquid separator 54a.

[0136] In the refrigerator 1 of the modified example 1, no refrigerant flows through the refrigeration evaporator 14b (more precisely, the refrigerant piping used when cooling the refrigeration evaporator 14b) during defrosting. However, as in the third embodiment, the high-temperature refrigerant discharged from the compressor 24 during defrosting heats the refrigeration evaporator 14b, heating and melting the frost adhering to the refrigeration evaporator 14b, while the refrigerator evaporator 14a cools and absorbs heat in the refrigerator compartment 2.

[0137] In such refrigeration cycles, the same problems arise during defrosting. Therefore, it is effective to block the three-way valve 52 during defrosting to block the refrigerant flow from the check valve 130 or three-way valve 101 to the three-way valve 52, including the heat dissipation section 50 and the dryer 51, thereby reducing the amount of refrigerant that can be circulated during defrosting and suppressing liquid return.

[0138] [Differentiation 2] Figure 12 is a schematic diagram showing the refrigeration cycle 200b of the modified example 2 of the third embodiment.

[0139] In this modified example, a seventh branch junction 113, where the refrigerant flow path for defrosting operation and the refrigerant flow path for refrigeration cooling operation merge, is provided in the refrigerant flow path between the second capillary tube 53b and the refrigeration evaporator 14b, and an eighth branch junction 114, where the refrigerant flow path for defrosting operation and the refrigerant flow path for refrigeration cooling operation diverge, is provided in the refrigerant flow path between the refrigeration evaporator 14b and the refrigeration gas-liquid separator 54b.

[0140] In defrosting operation, the compressor 24 is driven by opening the outlet 101b side of the three-way valve 101 and closing the two-way valve 112. As a result, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 24 passes through the outlet 101b of the three-way valve 101, then through the first defrosting refrigerant flow path 59 and the seventh branch junction 113 to the refrigeration evaporator 14b, where it heats the refrigeration evaporator 14b, then through the eighth branch junction 114, the second defrosting refrigerant flow path 59b and the defrosting capillary tube 103 to the refrigeration evaporator 14a, where it absorbs heat, and finally returns to the compressor 24 via the refrigeration gas-liquid separator 54a. In other words, similar to the third embodiment, the high-temperature refrigerant discharged from the compressor 24 during defrosting operation is flowed through the refrigerant piping of the refrigeration evaporator 14b, thereby heating and melting the frost adhering to the refrigeration evaporator 14b, and the refrigeration evaporator 14a is used to cool and absorb heat in the refrigerator compartment 2. On the other hand, in the third embodiment, the direction of refrigerant flow in the refrigeration evaporator 14b differed between the refrigeration cooling operation and the defrosting operation, but in this embodiment, the refrigerant flows in the same direction to the refrigeration evaporator 14b during both the refrigeration cooling operation and the defrosting operation.

[0141] In such refrigeration cycles, the same problems arise during defrosting. Therefore, it is effective to block the three-way valve 52 during defrosting to block the refrigerant flow from the check valve 130 or three-way valve 101 to the three-way valve 52, including the heat dissipation section 50 and the dryer 51, thereby reducing the amount of refrigerant that can be circulated during defrosting and suppressing liquid return.

[0142] In addition, in the modified example 2, as a third means of suppressing excessive cooling of the refrigerant evaporator 14a, it is conceivable to bypass the refrigerant evaporator 14a by opening the two-way valve 112 during defrosting operation, and in this case as well, control that reduces the amount of circulating refrigerant during defrosting operation is effective.

[0143] In the defrosting operation of Modification 2 shown in Figure 12 (compressor 24 is driven with the outlet 101b side of the three-way valve 101 open), the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 24 passes through the outlet 101b of the three-way valve 101, and then flows to the refrigeration evaporator 14b via the first defrosting refrigerant flow path 59 and the seventh branch junction 113. If the two-way valve 112 is closed, the refrigerant flows to the refrigeration evaporator 14a via the eighth branch junction 114, the second defrosting refrigerant flow path 59b, and the defrosting capillary tube 103. However, when the two-way valve 112 is opened, the refrigerant in the refrigeration evaporator 14b bypasses the refrigeration evaporator 14a and returns to the compressor 24. In other words, the same defrosting operation as in the first embodiment can be performed. On the other hand, in this case, since the refrigerant evaporator 14a is bypassed, excessive cooling by the refrigerant evaporator 14a can be suppressed. However, just as when the refrigerant fan 9a is stopped (the first solution), the vaporization of the refrigerant in the refrigerant evaporator 14a is suppressed, making liquid backflow more likely. Therefore, it is effective to block the refrigerant up to the three-way valve 52 and reduce the amount of circulating refrigerant.

[0144] The present invention is not limited to the embodiments described above, and includes various modifications other than those shown herein. For example, the embodiments described above are described in detail for the purpose of clearly illustrating the present invention, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace some of the configurations of the embodiments with other configurations, and it is also possible to add other configurations to the configurations of the embodiments. In addition, it is possible to add, delete, or replace some of the configurations of each configuration with other configurations.

[0145] For example, instead of the capillary tubes 53 and 103 of refrigerator 1, a pressure-controllable expansion valve (not shown) may be provided. Such a refrigerator can adjust the refrigerant pressure as needed.

[0146] Furthermore, although the embodiments described above disclose a defrosting operation using a refrigerant, a defrosting method that generates heat using, for example, an electric heater installed below the evaporator 14 and the refrigeration evaporator 14b may also be used in combination. [Explanation of symbols]

[0147] 1...Refrigerator, 2...Refrigerator compartment, 7...Freezer compartment, 9...Evaporator fan, 9a...Refrigerator fan (first fan), 9b...Freezer fan (second fan), 14...Evaporator, 14a...Refrigerator evaporator (first evaporator), 14b...Freezer evaporator (second evaporator), 24...Compressor, 50...Heat dissipation unit, 52...Three-way valve (second refrigerant control means), 52c...Two-way valve (second refrigerant control means), 53...Capillary tube (pressure reduction means), 53a...First capillary tube (first pressure reduction means), 53a...Second capillary tube (second pressure reduction means), 101...Three-way valve (first refrigerant control means), 103...Defrosting capillary tube (third pressure reduction means), 112...Two-way valve (third refrigerant control means), 301...Defrosting refrigerant piping

Claims

1. The system comprises a storage chamber, an evaporator for cooling the storage chamber, a compressor, a heat dissipation section, a pressure reducing means, a first refrigerant control means for switching the refrigerant flow path, a second refrigerant control means capable of blocking the refrigerant flow path, and a branching / merging section capable of merging and branching the refrigerant flow paths. The refrigerant discharged from the compressor flows in the following order: the first refrigerant control means, the heat dissipation unit, the pressure reducing means, the branching and merging unit, and the evaporator, returning to the compressor and cooling the evaporator in a cooling operation. The system includes a defrosting operation in which the first refrigerant control means is switched so that the refrigerant discharged from the compressor bypasses part or all of the heat dissipation unit and the pressure reducing means, flows in the order of the first refrigerant control means, the branching and merging unit, and the evaporator, and returns to the compressor to heat the evaporator, The second refrigerant control means is provided in the refrigerant flow path during the cooling operation, either midway through the heat dissipation section or between the outlet and the branch / confluence section. A refrigerator characterized in that it is possible to perform the defrosting operation while the second refrigerant control means is blocked and the refrigerant is retained in the heat dissipation section.

2. The second refrigerant control means can also switch the refrigerant flow path. The pressure reduction means includes a first pressure reduction means and a second pressure reduction means. The refrigerator according to claim 1, characterized in that the second refrigerant control means can block both the first pressure reducing means and the second pressure reducing means during the defrosting operation, and can switch between the first pressure reducing means and the second pressure reducing means.

3. The storage room comprises a refrigerator and a freezer, and the evaporator comprises a first evaporator for cooling the refrigerator and a second evaporator for cooling the freezer. The cooling operation includes a refrigerating cooling operation in which the refrigerant discharged from the compressor flows in the order of the first refrigerant control means, the heat dissipation unit, the second refrigerant control means, the first pressure reducing means, the third branch / confluence unit, and the first evaporator, returning to the compressor and cooling the first evaporator, and a refrigeration cooling operation in which the second refrigerant control means is switched so that the refrigerant discharged from the compressor flows in the order of the first refrigerant control means, the heat dissipation unit, the second refrigerant control means, the second pressure reducing means, the fifth branch / confluence unit, and the second evaporator, returning to the compressor and cooling the second evaporator. The defrosting operation described above is a defrosting operation in which the first refrigerant control means is switched so that the refrigerant discharged from the compressor bypasses part or all of the heat dissipation unit and the pressure reducing means, and flows in the order of the first refrigerant control means, the sixth branch / junction unit, the second evaporator, and the first evaporator, returning to the compressor and heating the second evaporator. The refrigerator according to claim 2, characterized in that the defrosting operation can be performed with the second refrigerant control means blocked and the refrigerant retained in the heat dissipation section.

4. When the defrosting operation starts, the second refrigerant control means is closed, or During the defrosting operation, the second refrigerant control means is closed. A refrigerator according to any one of claims 1 to 3, characterized in that it is capable of being operated.

5. The refrigerator according to any one of claims 1 to 3, characterized in that, when the temperature inside the refrigerator compartment and / or the surrounding area of ​​the refrigerator is high at the start of the defrosting operation, the time from the start of the defrosting operation until the closing of the second refrigerant control means is made longer compared to when the temperature inside the refrigerator compartment and / or the surrounding area of ​​the refrigerator is low.

6. A refrigerator according to any one of claims 1 to 3, characterized in that it includes a refrigerant recovery operation in which the second refrigerant control means is closed and the compressor is operated with the first refrigerant control means flowing refrigerant to the heat dissipation section, and the refrigerant recovery operation is performed before the defrosting operation.

7. The refrigerator according to claim 6, characterized in that it determines whether or not to perform the refrigerant recovery operation according to the ambient temperature of the refrigerator.

8. The refrigerator according to claim 6, characterized in that when the surrounding area of ​​the refrigerator is cold, the refrigerant recovery operation performed before the defrosting operation is performed for a longer period than when the surrounding area of ​​the refrigerator is hot.

9. The refrigerator according to claim 3, further comprising a first fan for blowing the cold air generated by the first evaporator into the refrigerator compartment, and characterized in that, during the defrosting operation, the first fan is stopped or operated at a lower speed than during the refrigeration cooling operation.

10. The refrigerator according to claim 9, characterized in that when the surrounding area of ​​the refrigerator is cold, the first fan is operated at a lower speed during the defrosting operation than when the surrounding area of ​​the refrigerator is hot.

11. As the pressure reducing means, a third pressure reducing means for reducing the refrigerant pressure during the defrosting operation is further provided. The refrigerator according to claim 3, characterized in that the flow resistance of the third pressure reducing means is smaller than the flow resistance of the first pressure reducing means, and the flow resistance of the first pressure reducing means is smaller than that of the second pressure reducing means.

12. The refrigerator according to claim 1, characterized in that a third refrigerant control means is provided in the flow path from the first refrigerant control means to the heat dissipation section, or in the middle of the heat dissipation section, for suppressing backflow to the first refrigerant control means side during the cooling operation.

13. The refrigerator according to claim 1, characterized in that the volume in the refrigerant flow path from the first refrigerant control means to the second refrigerant control means is greater than the volume when all the refrigerant sealed in the refrigeration cycle is liquefied.

14. The refrigerator according to claim 1, characterized in that the second refrigerant control means is closed when the compressor is stopped.

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