JP7797230B2 - Refrigerator - Google Patents

Description

This technology relates to refrigerators.

It is known that compressors, which are part of the refrigeration cycle, can shorten their lifespan and produce abnormal noises when overloaded. For this reason, technologies have been proposed to prevent compressor overload operation, one example of which is disclosed in Patent Document 1. Patent Document 1 discloses technology to prevent compressor overload operation in a refrigeration cycle installed in a vending machine by adjusting the rotation speed of the blower fan attached to the evaporator (cooler) or by changing the rotation speed of the compressor to adjust the amount of refrigerant circulating.

Japanese Patent Application Laid-Open No. 2004-184019

One type of equipment that utilizes a refrigeration cycle is a rapid cooling cabinet, which rapidly cools high-temperature foods in a short amount of time. In recent years, the use of rapid cooling cabinets has expanded, with demand also increasing in small stores. Small stores require inexpensive products that save space, but the reality is that it is difficult to achieve both miniaturization and avoiding the aforementioned compressor overload. For example, adjusting the rotation speed of the blower fan or compressor by applying the technology described in Patent Document 1 to avoid compressor overload requires an inverter circuit or the like, which increases installation space and manufacturing costs. Furthermore, the reality is that there are currently no small blower fans on the market that can adjust their rotation speed while still ensuring the airflow required for rapid cooling.

The technology described in this specification was developed based on the above-mentioned circumstances, and aims to realize a refrigerator that can prevent compressor overload operation while suppressing increases in manufacturing costs and space.

The refrigerator related to the technology described in this specification comprises a cooling device having a refrigerator main body, a compressor that compresses a refrigerant, a condenser that liquefies the refrigerant compressed by the compressor, and an evaporator that vaporizes the refrigerant from the condenser to generate cool air; multiple circulation fans that circulate air within the refrigerator main body; a temperature sensor that can detect the condensation temperature of the condenser; and a control unit, wherein each of the multiple circulation fans can be operated individually at a constant speed; and the control unit operates the compressor and the multiple circulation fans during cooling operation to cool the interior of the refrigerator main body, and stops at least one of the multiple operating circulation fans when the temperature detected by the temperature sensor is equal to or higher than a first threshold temperature.

By monitoring the condensing temperature of the condenser using a temperature sensor, if the temperature detected by the temperature sensor exceeds a first threshold temperature, it is determined that the refrigerant temperature (refrigerant pressure) in the compressor is high and the compressor is operating under overload, and the number of operating circulation fans is reduced to reduce the amount of air circulating within the refrigerator body. This reduces the amount of heat exchanged (heat absorption) in the evaporator, allowing refrigerant with reduced pressure and temperature to be returned to the compressor, thereby preventing the compressor from operating under overload. Furthermore, to reduce the amount of air circulating within the refrigerator body, it is sufficient to stop one of the multiple circulation fans; there is no need to reduce the circulation fan's rotation speed. There is no need to install an inverter circuit or the like to vary the circulation fan's rotation speed, which avoids increases in cost and space.

Furthermore, during the cooling operation, the control unit stops the compressor if the temperature detected by the temperature sensor remains equal to or higher than the first threshold temperature for a predetermined period of time. By stopping the compressor, overload operation of the compressor can be more reliably prevented and the compressor can be protected.

Furthermore, during the cooling operation, the control unit stops the compressor when the temperature detected by the temperature sensor is equal to or higher than a second threshold temperature that is greater than the first threshold temperature. By stopping the compressor, overload operation of the compressor can be more reliably prevented and the compressor can be protected.

The condenser is a microchannel heat exchanger that exchanges heat with the air passing through it, and is equipped with a condenser fan that cools the microchannel heat exchanger, an air filter installed on the air inlet side of the microchannel heat exchanger, and an installation sensor that detects the presence or absence of the air filter. If the installation sensor detects that the air filter is not installed, the control unit does not operate the compressor, the condenser fan, and the multiple circulation fans. Using a microchannel heat exchanger as a condenser allows for a smaller size, but it is prone to clogging due to the adhesion of foreign matter such as dust and oily smoke. Therefore, if the installation sensor detects that an air filter is not installed, the control unit does not operate the various devices related to operation (does not operate). This allows for a smaller condenser while preventing clogging.

The device also includes a notification unit capable of issuing a warning, and the control unit issues a warning via the notification unit when the installation sensor detects that the air filter is not installed. In this way, a warning can be issued if the air filter has been left unattached.

The temperature sensor is a condenser temperature sensor installed in the refrigerant pipe on the refrigerant outlet side of the condenser. In this way, the condenser temperature sensor can easily detect the condensing temperature of the condenser.

The technology described in this specification makes it possible to realize a refrigerator that can prevent compressor overload operation while minimizing manufacturing costs and space requirements.

1 is a perspective view of a refrigerator according to a first embodiment; Perspective view of the refrigerator with the door open A cross-sectional view of line A-A in FIG. Left side view of the refrigerator 4B-B line cross section 4 is a cross-sectional view taken along line CC in FIG. Schematic diagram of the refrigeration cycle Enlarged view of the upper part of the door in Figure 4 A perspective view of a microchannel heat exchanger and a defrosting heater. A plan view showing the structure of a microchannel heat exchanger. A perspective view schematically showing flat refrigerant tubes of a microchannel heat exchanger. Flowchart for controlling cooling operation

<Embodiment 1>
A refrigerator 10 according to the first embodiment will be described with reference to Figures 1 to 12. Note that the symbols F, Rr, L, R, U, and D shown in the figures respectively indicate the front and rear in the front-to-rear direction of the refrigerator 10, the left and right in the width direction (left-right direction) when viewed from the front, and the top and bottom in the vertical direction (up-down direction). However, these directions are merely defined for convenience and should not be interpreted in a limiting manner.

Refrigerator 10 is a rapid cooling cabinet (a blast chiller) that rapidly cools high-temperature food (an example of an object to be cooled), for example, after cooking. Refrigerator 10 can rapidly cool (including freezing) food by passing through temperature ranges where bacteria are likely to grow (e.g., +10°C to +60°C) and ice crystal growth temperature ranges (e.g., -1°C to -5°C) where water in food freezes. Refrigerator 10 is a compact rapid cooling cabinet suitable for use in small stores, with external dimensions of, for example, approximately 500 mm (horizontal) x 500 mm (front-to-back) x 510 mm (vertical). However, the technology described herein is not limited to compact refrigerators 10, but can also be applied to medium- to large-sized refrigerators.

As shown in Figures 1 to 6, the refrigerator 10 has a generally rectangular parallelepiped shape overall and generally comprises a refrigerator body 11, a cooling device 12 for cooling a storage chamber 14 formed within the refrigerator body 11, a machine room 15 located above the refrigerator body 11, and an insulated door 13 for opening and closing a first front opening 11S of the refrigerator body 11. The refrigerator body 11 is an insulated box having a first front opening 11S and is composed of walls (more specifically, a ceiling wall 11A, a bottom wall 11B, a left side wall 11C, a right side wall 11D, and a rear wall 11E) filled with an insulating material such as urethane foam.

As shown in Figures 2 and 3 and 5 and 6, a cooling case (fan cover) 17 is provided inside the refrigerator body 11 (hereinafter sometimes simply referred to as the interior) along the right side wall 11D. Inside the cooling case 17, an evaporator 23 that forms part of the cooling device 12 and multiple (two in this embodiment) evaporator fans 25 (an example of a circulation fan) are housed, lined up in this order from the right side wall 11D side. A defrosting heater 24 that melts frost adhering to the evaporator 23 is provided between the evaporator 23 and the right side wall 11D. The defrosting heater 24 also serves as a heating means for raising the temperature inside the refrigerator.

The evaporator 23 is a so-called microchannel heat exchanger, the configuration of which will be described in detail later. The defrost heater 24 is a sheathed heater that is serpentinely arranged along one side (right side) of the evaporator 23 (Figure 9). The defrost heater 24 may be any heater other than a sheathed heater as long as it can perform heating functions. The evaporator fan 25 is equipped with a waterproof, constant-speed DC motor. The DC motor of each evaporator fan 25 is connected to a relay circuit on the control board 62A (described later) and can be driven individually.

As shown in Figures 5 and 6, a rear duct 20 is provided on the rear wall 11E of the refrigerator body 11. The right end of the rear duct 20 is connected to the rear end of the cooling case 17, and the interior of the rear duct 20 (the space surrounded by the rear wall 11E and the rear duct 20) serves as a flow path for returning air from the cooling case 17 to the storage chamber 14. The rear duct 20 is formed with multiple air outlets 20A, and air that flows into the rear duct 20 is blown out from the air outlets 20A into the storage chamber 14. In addition, a drain outlet 11B1 is provided on the rear of the bottom wall 11B for draining water generated when cleaning the interior of the refrigerator, and a drain hose 90 is connected to the drain outlet 11B1 for draining the water to the outside.

The area inside the refrigerator body 11, surrounded by the ceiling wall 11A, bottom wall 11B, left side wall 11C, cooling case 17, and rear duct 20, forms the storage chamber 14 for storing items to be cooled. As shown in Figure 6, the left side wall 11C and cooling case 17 are provided with a multi-tiered tray support structure 16, and trays carrying food are inserted and removed from the storage chamber 14 through the first front opening 11S. The trays are supported by the tray support structure 16 and can be stored in multiple rows vertically.

As shown in Figure 3, the left wall portion 17A of the cooling case 17, where the tray support structure 16 is provided, has multiple intake ports 17A1. The multiple intake ports 17A1 are located at least opposite the evaporator fan 25, and when the evaporator fan 25 is activated, the air inside the storage chamber 14 is drawn into the cooling case 17 through the intake ports 17A1. The cooling case 17 also has an openable/closable structure, and by removing the fastener 17B, the cooling case 17 can be opened so that the storage section for the evaporator fan 25 and the storage section for the evaporator 23 are separated. Opening the cooling case 17 makes it easier to clean and dry the evaporator fan 25 and evaporator 23.

With the above-described structure of the refrigerator body 11, when the evaporator fan 25 is activated, the air inside the storage chamber 14 is drawn into the evaporator fan 25 through the intake port 17A1 of the cooling case 17, passes through the evaporator 23, and then flows into the rear duct 20, as shown by the arrows in Figure 5. The air inside the rear duct 20 then returns to the storage chamber 14 through the outlet port 20A. This circulation flow path is formed inside the refrigerator, and an internal temperature sensor 21 that detects the internal temperature is provided at a position where the air passing through this circulation flow path hits. In this embodiment, the internal temperature sensor 21 is provided inside the rear duct 20.

As shown in Figures 2 to 6, the machine room 15 is located on the ceiling wall 11A of the refrigerator body 11. The left, right, rear, and top of the machine room 15 are covered with a panel 15A having multiple air vents 15A1. The top surface of the panel 15A can be used to mount other equipment, such as an oven cooker, by attaching a separate mounting member, thereby improving convenience for use in small stores. As shown in Figure 4, a second front opening 15S is provided on the front of the machine room 15, and a horizontally elongated first electrical box (operation box) 61 is attached above the second front opening 15S. An air filter 18 is attached to the second front opening 15S to allow air to pass through while preventing dust and other foreign matter from entering the machine room 15 (more specifically, the condenser 28, described below) from the outside. As shown in Figures 4 and 8, when the door 13 is closed, the opening edge of the second front opening 15S is covered in front by the door 13 with a gap G1.

As shown in Figure 2, the air filter 18 has a structure in which a mesh-like sheet member 18B is attached to a frame body 18A. The air filter 18 is detachably attached to the edge of the second front opening 15S of the machine room 15, allowing the user to open the door 13, remove the air filter 18, and perform cleaning, etc. In addition, an attachment sensor 19 that detects the presence or absence of the air filter 18 is provided on the edge of the second front opening 15S. The attachment sensor 19 can be a sensor that performs electrical or mechanical detection, or a switch (e.g., a reed switch or microswitch), and there is no particular limitation on the type.

As shown in Figures 1 and 2, the door 13 is a swinging right-opening door that is large enough to cover the front of the refrigerator body 11 and the lower front of the machine room 15. The door 13 is swingably attached to the right side of the opening edge of the first front opening 11S of the refrigerator body 11 by a hinge member 40. The portion of the door 13 that covers the front of the refrigerator body 11 is thermally insulated. A gasket 13A is provided on the surface (rear surface) of the door 13 facing the refrigerator body 11, so that it corresponds to the opening edge of the first front opening 11S. The door 13 can open and close the first front opening 11S by the gasket 13A coming into close contact with the opening edge of the first front opening 11S. On the other hand, the portion of the door 13 that covers the lower front of the machine room 15 is not thermally insulated, and no gasket is provided in the portion that corresponds to the opening edge of the second front opening 15S. The door 13 is closed without sealing the second front opening 15S, leaving a gap G1 between the door 13 and the opening edge of the second front opening 15S (Figure 8). When the door 13 is closed, the second front opening 15S and the air filter 18 are covered from the front by the door 13 and cannot be seen from the front.

As shown in Figures 4 and 8, a gap G1 is formed at the upper left and right sides of the door 13 when the door is closed. This allows outside air to flow from the gap G1 into the machinery compartment 15 through the second front opening 15S. In other words, an intake flow path for outside air flowing from the gap G1 to the second front opening 15S is formed at the upper left and right sides of the door 13. The intake flow path allows outside air to flow into the machinery compartment 15 even when the door 13 is closed, making it easier to increase the amount of air flowing into the condenser 28 in the machinery compartment 15. This allows the condenser 28 to be efficiently air-cooled, lowering the condensing temperature of the refrigerant in the condenser 28 and reducing the load on the compressor 27. Furthermore, reducing the load on the compressor 27 reduces the power consumption required to operate the compressor 27. Furthermore, it is possible to suppress condensation that occurs on the top of the gasket 13A of the door 13 due to outside air passing through the intake flow path.

As shown in Figures 2 to 6, the machinery compartment 15 houses the machinery (compressor 27, condenser 28, condenser fan 29, etc.) that constitutes the cooling system 12, as well as the first electrical box 61 and second electrical box 62. The first electrical box 61 is attached to the upper front side of the machinery compartment 15 and has a horizontally long box shape. The left-right length of the first electrical box 61 is approximately the same as the left-right length of the door 13, and the bottom surface of the first electrical box 61 covers the entire top surface of the door 13 from above. The front surface of the first electrical box 61 protrudes forward relative to the opening edge of the second front opening 15S of the machinery compartment 15 and the air filter 18, and the protruding length is such that it is approximately flush with the front surface of the door 13 when the door 13 is closed (Figure 8).

As shown in Figures 1 to 3, the first electrical box 61 houses a display unit 61A that displays information, an operation unit 61B with various operation buttons, and an operation board 61C. The display unit 61A and operation unit 61B are located on the front of the first electrical box 61. The display unit 61A displays the current operating mode and various messages. The display unit 61A also functions as an alarm unit. For example, if the air filter 18 is not installed, a warning (including an error message) is displayed on the display unit 61A to notify the user of the forgotten installation. Note that the display unit 61A is merely one example of an alarm unit, and the alarm unit may be a sound-generating device such as a buzzer, or a combination of these. The user can operate the operation unit 61B to select the operating mode of the refrigerator 10 (cooling operation, drying operation, etc.) and to issue a command to start operation. The display unit 61A and operation unit 61B are connected to the control board 62A of the second electrical box 62 (described later) via the operation board 61C. The display unit 61A and operation unit 61B may be integrated into a display device with touch panel functionality.

As shown in Figures 3 and 6, the second electrical box 62 is located to the rear right of the first electrical box 61. The second electrical box 62 houses a control board 62A that includes circuits for controlling the operation of the refrigerator 10 and supplying power, as well as a memory unit. The control board 62A is electrically connected to an operation board 61C inside the first electrical box 61, and the control board 62A and operation board 61C form a control unit 60 that controls various devices in the refrigerator 10. The control unit 60 executes a control program recorded in the memory unit and controls the compressor 27, condenser fan 29, evaporator fan 25, defrost heater 24, etc. based on the detection results of each sensor and the operation of the operation unit 61B, thereby operating the refrigerator 10.

As shown in FIG. 7, the cooling device 12 includes a compressor 27, a condenser 28, a condenser fan 29, a dryer 30, an expansion valve (internal equalization type) 31, and an evaporator 23. The compressor 27, condenser 28, dryer 30, expansion valve 31, and evaporator 23 are connected by refrigerant pipes 12A, and refrigerant is circulated in a predetermined direction to form a known refrigeration cycle. The cooling device 12 also includes a pressure-equalizing solenoid valve 32 in parallel with the compressor 27.

The compressor 27 is a constant-speed compressor equipped with a constant-speed motor. The compressor 27 uses the motor as a power source to draw in and compress refrigerant gas, then discharges high-temperature, high-pressure refrigerant gas. Constant-speed compressors do not require components (such as an inverter circuit) to vary the motor's rotation speed, making them smaller and less expensive than variable-speed inverter compressors. The condenser 28 cools and liquefies the refrigerant gas compressed by the compressor 27 using air blown by the condenser fan 29. The condenser 28 is installed at an angle behind the second front opening 15S and the air filter 18 of the machinery compartment 15 (Figure 3). The evaporator 23 reduces the pressure of the refrigerant liquid from the condenser 28 using an expansion valve 31 before vaporizing it, thereby cooling the air passing through the evaporator 23 through heat exchange. The refrigerant gas from the evaporator 23 is returned to the compressor 27.

As shown in Figure 3, the condenser fan 29 is installed upright behind the condenser 28. When the condenser fan 29 is activated, outside air flows in through the second front opening 15S and passes through the condenser 28 from front to back, air-cooling the condenser 28. The refrigerant passing through the condenser 28 is a high-temperature gas near the inlet on the compressor 27 side, and as it progresses through the condenser 28, it cools and its temperature decreases. When the temperature of the refrigerant gas drops to a saturation temperature (condensation temperature) corresponding to the pressure, it begins to condense into a liquid. The liquefaction rate of the refrigerant gas increases as it progresses through the condenser 28, and it becomes almost liquid near the outlet on the dryer 30 side. The dryer 30 removes moisture that has become mixed in the refrigerant.

As shown in Figures 4 and 7, a condenser temperature sensor 26 (specifically, a temperature thermistor) is attached to the refrigerant outlet side of the condenser 28 in a thermistor holder. At the refrigerant outlet side of the condenser 28, most of the refrigerant is condensed and liquefied, and its temperature matches the condensation temperature. Therefore, the condenser temperature sensor 26 detects the refrigerant condensation temperature. Furthermore, because the refrigerant condensation temperature changes depending on the refrigerant pressure, the condenser temperature sensor 26 can indirectly detect the refrigerant pressure. Furthermore, if the refrigeration temperature (refrigerant pressure) of the refrigerant in the condenser 28 is high, the refrigerant temperature (refrigerant pressure) in the compressor 27, which is flowing refrigerant into the condenser 28, is also high. Therefore, by monitoring the temperature T26 detected by the condenser temperature sensor 26, it is possible to determine whether the refrigerant temperature (refrigerant pressure) in the compressor 27 is high and, ultimately, whether the compressor 27 is operating under overload.

Both the condenser 28 and the evaporator 23 are microchannel heat exchangers with the same basic structure. Therefore, the following describes the structure of a microchannel heat exchanger using the evaporator 23 as an example. As shown in Figures 9 to 11, the evaporator 23 includes a hollow cylindrical first head tube 23A and a second head tube 23B connected to the refrigerant tube 12A, a plurality of flat refrigerant tubes 23C connecting the two head tubes 23A and 23B, and numerous fins 23D disposed between the flat refrigerant tubes 23C. The first head tube 23A is connected to the refrigerant tube 12A on the refrigerant inlet side (expansion valve 31 side), and refrigerant flows in from the refrigerant tube 12A. The second head tube 23B is connected to the refrigerant tube 12A on the refrigerant outlet side (compressor 27 side), and refrigerant flows out to the refrigerant tube 12A. The flat refrigerant tube 23C has a plurality of channels 23C1, which are minute internal cavities. The maximum inner diameter of each channel 23C1 is small, for example, approximately 1 mm to 2 mm. Each channel 23C1 serves as a refrigerant flow path through which refrigerant flowing in from the first head tube 23A passes before flowing out to the second head tube 23B. The fins 23D are thin plates arranged in a bellows (triangular wave) shape between adjacent flat refrigerant tubes 23C. The fins 23D are bonded to the outer surfaces of the flat refrigerant tubes 23C, and the increased surface area of the fins 23D improves heat exchange capacity.

Using microchannel heat exchangers for the condenser 28 and evaporator 23 allows for their miniaturization. For example, the thickness (horizontal length) of the evaporator 23 in this embodiment is approximately 30 mm, which is thinner than the approximately 55 mm thickness of a fin-and-tube heat exchanger (a heat exchanger with multiple flat fins and a single refrigerant tube that snakes through the multiple fins) with equivalent heat exchange capacity. However, because the spacing between the fins 23D (fin pitch L23D) of a microchannel heat exchanger is small, its use in the condenser 28 makes it prone to clogging due to the adhesion of foreign matter such as dust and oily smoke. Therefore, in this embodiment, if the attachment sensor 19 detects that the air filter 18 is not attached, the control unit 60, as described below, controls the refrigerator 10 not to operate. This allows for a smaller condenser 28 while preventing clogging due to the air filter 18 and reducing the frequency of maintenance work by a maintenance technician.

Furthermore, when a microchannel heat exchanger is used for the evaporator 23, clogging due to frosting is more likely to occur due to the small fin pitch. Furthermore, defrost water generated from frost melted during defrosting operation is likely to remain, raising concerns that the defrost water may refreeze and cause further clogging. Therefore, in this embodiment, the control unit 60 performs a drying operation after the defrosting operation to dry the remaining defrost water. This makes it possible to reduce the size of the evaporator 23 while suppressing clogging due to frost and reducing the frequency of maintenance by a maintenance technician.

Next, the operation of the refrigerator 10 will be described in detail. The operating modes of the refrigerator 10 are roughly divided into cooling operation (rapid cooling operation), defrosting operation, and drying operation, and each operating mode will be described below. If the attachment sensor 19 detects that the air filter 18 is not attached, the control unit 60 will not start each operation and will display a warning on the display unit 61A. This makes it easier to prevent clogging of the condenser 28, even when a microchannel heat exchanger is used for the condenser 28, as in this embodiment. Note that "not starting operation" means "not operating equipment that should be operated during operation."

Cooling operation is an operating mode for rapidly cooling hot cooked food. Cooling operation is initiated when the user places a tray containing food in the storage chamber 14 and then operates the operating unit 61B to initiate cooling operation. During cooling operation, the control unit 60 activates the compressor 27 and condenser fan 29 of the cooling device 12, as well as the evaporator fan 25. As shown by the arrows in FIG. 5 , the air inside the storage chamber 14 is drawn into the evaporator fan 25 through the air inlet 17A1 and cooled as it passes through the evaporator 23. The cooled air from the evaporator 23 passes through the rear duct 20 and is blown into the storage chamber 14 through the air outlet 20A. The blown air travels forward, passing between the trays and other gaps before being drawn into the air inlet 17A1 of the cooling case 17. This allows cool air to circulate within the refrigerator, rapidly cooling the food. The air inside the refrigerator also circulates along the same circulation path during the drying operation described below.

During cooling operation of the refrigerator 10, high-temperature food is rapidly cooled, which can easily place a heavy load on the compressor 27. Therefore, in this embodiment, the control unit 60 performs control to prevent the compressor 27 from overloading during cooling operation. This control will be described with reference to the flowchart in Figure 12. When cooling operation begins, the control unit 60 activates the two evaporator fans 25, the condenser fan 29, and the compressor 27 (S10, S12, S14). The control unit 60 also reads the temperature T26 detected by the condenser temperature sensor 26 and compares it with a predetermined first threshold temperature Tth1 (e.g., +54°C) (S16). If the detected temperature T26 is equal to or greater than the first threshold temperature Tth1 (YES in S16), as previously described, the refrigerant temperature (refrigerant pressure) in the compressor 27 is high, raising concerns that the compressor 27 may be overloaded (overheated). Therefore, the control unit 60 stops one of the two evaporator fans 25 (S18).

Stopping one evaporator fan 25 reduces the amount of warm air drawn into the evaporator 23 from the storage chamber 14, reducing the amount of heat exchanged (heat absorbed) in the evaporator 23 and reducing the pressure of the refrigerant gas vaporizing in the evaporator 23 (refrigerant pressure at the outlet side). As a result, refrigerant with reduced pressure and temperature can be returned to the compressor 27, preventing overload operation of the compressor 27. Furthermore, when reducing the airflow rate of the evaporator fan 25, as shown in step S18 of FIG. 12, it is sufficient to stop one evaporator fan 25 and reduce the number of operating fans; there is no need to reduce the rotational speed of the evaporator fan 25. Therefore, there is no need to install an inverter circuit or the like to vary the rotational speed of the evaporator fan 25, and overload operation of the compressor 27 can be prevented without increasing costs or space.

Furthermore, if the load on the compressor 27 further increases, the control unit 60 stops the compressor 27 itself. More specifically, if the detected temperature T26 of the condenser temperature sensor 26 remains equal to or greater than the first threshold temperature Tth1 for a predetermined period of time (e.g., five minutes) (YES in S20), the control unit 60 stops the compressor 27 (S22). The compressor 27 generally has a specified upper limit for the refrigerant pressure (pressure operating range) to prevent components from being overloaded and damaged. Exceeding this upper limit can shorten the life of the compressor 27 or cause it to unexpectedly shut down. Therefore, in this embodiment, if the detected temperature T26 of the condenser temperature sensor 26 remains equal to or greater than the first threshold temperature Tth1 for a predetermined period of time (YES in S20), the control unit 60 determines that the load on the compressor 27 is high and there is a risk that the pressure may exceed the upper limit, and stops the compressor 27 (S22). This prevents the compressor 27 from operating under overload when the pressure exceeds the allowable upper limit, thereby protecting the compressor 27. If the temperature T26 detected by the condenser temperature sensor 26 falls below the first threshold temperature Tth1 (NO in S24), the control unit 60 operates the compressor 27 again (S14). This allows the cooling operation to continue while protecting the compressor 27.

In the above-described control, to determine whether the compressor 27 is in an overload state, the first determination condition is whether the detected temperature T26 of the condenser temperature sensor 26 is equal to or greater than the first threshold temperature Tth1 (S16), and the second determination condition is whether the detected temperature T26 of the condenser temperature sensor 26 remains equal to or greater than the first threshold temperature Tth1 for a predetermined period of time (S20). However, the second determination condition may be other than the condition in step S20 described above, as long as it is a condition that can determine whether the load on the compressor 27 is greater than the first determination condition. For example, the second determination condition may be whether the detected temperature T26 of the condenser temperature sensor 26 is equal to or greater than a second threshold temperature Tth2 (e.g., +60°C) that is greater than the first threshold temperature Tth1, and if the detected temperature T26 is equal to or greater than the second threshold temperature Tth2, the compressor 27 may be stopped (S22).

Defrosting operation is an operating mode in which the evaporator 23 is defrosted. Defrosting operation is performed as needed during cooling operation, or when the user operates the operation unit 61B to command the start of defrosting operation. In defrosting operation, the control unit 60 stops the compressor 27 and condenser fan 29 of the cooling device 12 and activates the evaporator fan 25 and defrost heater 24. In defrosting operation, the cooling device 12 is stopped and the defrost heater 24 is activated, heating the evaporator 23. This melts the frost that has adhered to the evaporator 23.

Drying operation is an operating mode used to dry the interior of the refrigerator. Drying operation is performed after defrosting operation, or by the user operating the operation unit 61B to initiate drying operation. The user also opens the door 13 slightly prior to starting drying operation, allowing air to be exchanged between the interior and exterior of the refrigerator. During drying operation, the control unit 60 operates the evaporator fan 25, defrost heater 24, and condenser fan 29 without operating the compressor 27. By circulating the air inside the refrigerator while raising and maintaining the interior temperature at approximately +40°C to +60°C using the defrost heater 24 and evaporator fan 25, while allowing air to be exchanged between the interior and exterior of the refrigerator, any moisture remaining in the refrigerator (e.g., cleaning water remaining in the storage chamber 14 and defrost water remaining in the evaporator 23) can be dried. As mentioned above, the evaporator 23 in this embodiment is a microchannel heat exchanger that is prone to clogging with frost, but by performing a drying operation after a defrosting operation, clogging of the evaporator 23 can be reliably prevented.

<Other Embodiments>
The technology described in this specification is not limited to the embodiments described above and in the drawings, and for example, the following embodiments are also included in the technical scope of the technology described in this specification.

(1) The number of evaporator fans 25 is not limited to two and may be three or more. In this case, in step S18 of FIG. 12, the control unit 60 stops at least one of the three or more evaporator fans 25, thereby reducing the amount of air being drawn into the evaporator 23 from the storage chamber 14.

(2) The circulation fan may be any fan other than the evaporator fan 25 installed adjacent to the evaporator 23, as long as it is capable of circulating air inside the refrigerator.

(3) During defrosting and drying operations, the control unit 60 may operate the evaporator fan 25 intermittently by repeatedly turning it on and off.

(4) During defrosting and drying operations, the control unit 60 may adjust the operation rate (power supply rate) of the defrost heater 24, or may perform defrosting and drying by blowing air from the evaporator fan 25 without operating the defrost heater 24.

(5) The heating means for the interior of the refrigerator may be something other than the defrost heater 24, such as a heater installed in the rear duct 20.

10: Refrigerator, 11: Refrigerator body, 12: Cooling device, 12A: Refrigerant pipe, 18: Air filter, 19: Mounting sensor, 23: Evaporator, 25: Evaporator fan (circulation fan), 26: Condenser temperature sensor, 27: Compressor, 28: Condenser, 29: Condenser fan, 60: Control unit, 61A: Display unit (alarm unit), T26: Detected temperature, Tth1: First threshold temperature, Tth2: Second threshold temperature

Claims (5)

A refrigerator body,
a cooling device including a compressor that compresses a refrigerant, a condenser that liquefies the refrigerant compressed by the compressor, and an evaporator that vaporizes the refrigerant from the condenser to generate cold air;
A plurality of circulation fans that circulate air within the cooling cabinet body;
a temperature sensor capable of detecting a condensation temperature of the condenser;
a control unit,
each of the plurality of circulation fans is independently operable at a constant speed;
The control unit, in a cooling operation for cooling the inside of the refrigerator main body,
activating the compressor and the plurality of circulation fans;
When the temperature detected by the temperature sensor is equal to or higher than a first threshold temperature, at least one of the operating circulation fans is stopped;
the condenser is a microchannel heat exchanger that exchanges heat with air passing through the condenser;
a condenser fan for cooling the microchannel heat exchanger;
an air filter provided on the air inlet side of the microchannel heat exchanger;
an attachment sensor that detects the presence or absence of the air filter;
The control unit of the refrigerator does not operate the compressor, the condenser fan, and the multiple circulation fans when the installation sensor detects that the air filter is not installed . The refrigerator according to claim 1, wherein the control unit stops the compressor when the temperature detected by the temperature sensor remains equal to or higher than the first threshold temperature for a predetermined period of time during the cooling operation. The refrigerator according to claim 1, wherein the control unit stops the compressor during the cooling operation when the temperature detected by the temperature sensor is equal to or higher than a second threshold temperature that is greater than the first threshold temperature. a notification unit capable of issuing a warning;
The refrigerator according to any one of claims 1 to 3, wherein the control unit issues a warning by the notification unit when the attachment sensor detects that the air filter is not provided. 5. The refrigerator according to claim 1, wherein the temperature sensor is a condenser temperature sensor provided in a refrigerant pipe on a refrigerant outlet side of the condenser.