Refrigerator

Abstract

A refrigerator includes a cooling circuit having a first flow path circulating a refrigerant connected in order of a compressor, a condenser, a capillary, and an evaporator, the cooling circuit including a hot gas bypass pipe provided to form a second flow path making the refrigerant compressed by the compressor flow from the compressor to the evaporator, a three-way valve provided in the first flow path between the compressor and the condenser and connected with the hot gas bypass pipe, and a two-way valve provided in the first flow path between the condenser and the capillary, the three-way valve being capable of making the refrigerant discharged from the compressor flow into the condenser or the hot gas bypass pipe, the two-way valve being capable of cutting off the flow of the refrigerant discharged from the condenser by being closed.

Description

TECHNICAL FIELD

[0001] The present application relates to a refrigerator, and more particularly, to a refrigerator that removes frost adhering to an evaporator by hot gas. BACKGROUND

[0002] An evaporator, which is one of cooling circuits of a refrigerator, can have frost adhering due to cooling of surrounding water vapor, and thus cooling performance can be degraded. To solve this problem, a hot gas defrosting method is known in which a hot gas bypass pipe connected to an upstream side of the evaporator is provided downstream of a compressor, which is one of the cooling circuits, and a high-temperature gas is temporarily caused to flow to the evaporator via the hot gas bypass pipe, thereby heating the evaporator to perform defrosting. In the hot gas defrosting method, if a liquid return amount of refrigerant flowing through the hot gas bypass pipe to the compressor increases, reliability of the compressor can be degraded, and thus, for example, in Patent Document 1, an invention is disclosed in which the liquid return amount to the compressor is reduced to improve reliability of a freezing cycle device.

[0003] [Prior Art Document]

[0004] [Patent Document]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-554766

[0006] However, the invention disclosed in Patent Document 1 needs to include a complex system in order to adjust the flow rate of refrigerant flowing through the hot gas bypass pipe, such as a flow rate adjuster connected to the hot gas bypass pipe and adjusting the flow rate of refrigerant flowing through the hot gas bypass pipe, a refrigerant state detection unit detecting a discharge superheat degree of refrigerant discharged from the compressor and a suction pressure of the compressor, and a defrosting control unit that closes the flow rate adjuster at the time of normal cooling operation and increases or decreases the flow rate of refrigerant flowing through the hot gas bypass pipe according to the discharge superheat degree and the suction pressure detected by the refrigerant state detection unit at the time of defrosting operation.

[0007] In view of the above, it is necessary to improve the existing refrigerator to solve the above problems. SUMMARY

[0008] An object of the present application is to provide a refrigerator that can more easily reduce the flow rate of refrigerant flowing through the hot gas bypass pipe without complicating the system and avoid degradation of defrosting capacity.

[0009] To achieve the above object, the present application provides a refrigerator comprising: a cooling circuit having a first flow path in which a refrigerant is circulated in the order of a compressor, a condenser, a capillary tube, and an evaporator, the compressor compressing the refrigerant sent from the evaporator, the condenser condensing the refrigerant sent from the compressor, the capillary tube expanding the refrigerant sent from the condenser, and the evaporator evaporating the refrigerant sent from the capillary tube, the cooling circuit including: a hot gas bypass pipe provided to form a second flow path in which the refrigerant compressed by the compressor flows from the compressor to the evaporator; a three-way valve provided in the first flow path between the compressor and the condenser and connected to the hot gas bypass pipe; and a two-way valve provided in the first flow path between the condenser and the capillary tube, the three-way valve being capable of causing the refrigerant discharged from the compressor to flow into the condenser or the hot gas bypass pipe, and the two-way valve being capable of cutting off the flow of the refrigerant discharged from the condenser by being closed.

[0010] Thus, in a refrigerator in which the evaporator is defrosted by a hot gas defrosting method, a three-way valve is provided downstream of the compressor and upstream of the condenser, and a two-way valve is provided downstream of the condenser and upstream of the capillary tube. A hot gas defrosting pipe is provided, which causes the refrigerant in a hot gas state to bypass from downstream of the compressor to upstream of the evaporator via the three-way valve. By adopting this structure of the cooling circuit, the flow path of the refrigerant can be changed. In addition, the flow of the refrigerant can be cut off. Therefore, it is expected that the flow rate of the refrigerant flowing through the hot gas bypass pipe can be easily reduced and the decrease in defrosting capacity can be suppressed without including a complex system.

[0011] Further, the refrigerator has a control device that switches the cooling circuit between a normal operation in which the evaporator is cooled and a defrosting operation in which the evaporator is defrosted, and the control device is capable of controlling which of the condenser and the hot gas bypass pipe the three-way valve causes the refrigerant to flow into and is also capable of controlling the opening and closing of the two-way valve, the control device, in the case of switching from the normal operation to the defrosting operation, controlling in such a manner that the three-way valve causes the refrigerant to flow to the condenser and closes the two-way valve, thereby causing the refrigerant to be discharged from the compressor to the condenser, and then the three-way valve causes the refrigerant to flow to the hot gas bypass pipe.

[0012] In this way, before defrosting, the refrigerant can be allowed to accumulate in the condenser by closing the two-way valve. Then, the three-way valve is switched to allow the refrigerant to flow to the hot gas bypass pipe to perform the defrosting action. By reducing the amount of refrigerant flowing in the cooling circuit during defrosting, the possibility of refrigerant condensation in a hot gas state is reduced. Therefore, the reduction in defrosting capacity can be suppressed.

[0013] Furthermore, a temperature sensor is provided in the evaporator, and the control device controls the three-way valve and the two-way valve according to the temperature measured by the temperature sensor during the defrosting operation to adjust the amount of refrigerant.

[0014] In this way, the control device can determine whether the defrosting capacity has decreased based on the temperature measured by the temperature sensor. Consequently, when it is detected that the amount of refrigerant circulating in the cooling circuit is too high or too low, the flow path of the refrigerant can be switched by switching the three-way valve and the two-way valve to adjust the amount of refrigerant circulating in the cooling circuit.

[0015] Furthermore, the inner diameter of the hot gas bypass pipe is larger than the inner diameter of the compressor's discharge pipe, and the refrigerant is discharged from the compressor through the discharge pipe.

[0016] Thus, in refrigerators that use hot gas defrosting to defrost the evaporator, the pressure loss of refrigerant flowing in the hot gas bypass pipe can be reduced, thereby inhibiting refrigerant condensation.

[0017] Furthermore, the inner diameter of the three-way valve is larger than the inner diameter of the compressor's discharge pipe.

[0018] Thus, in refrigerators that use hot air defrosting to defrost the evaporator, the pressure loss of refrigerant flowing in the three-way valve can be reduced, thereby inhibiting refrigerant condensation.

[0019] Furthermore, the compressed refrigerant is sent to the condenser through a first connecting pipe, which is equipped with the three-way valve and is divided into a first sub-pipeline and a second sub-pipeline.

[0020] Furthermore, the condensed refrigerant is sent to the capillary tube through a second connecting pipe, which is equipped with the two-way valve and is divided into a third sub-pipe and a fourth sub-pipe.

[0021] Furthermore, when the defrosting operation is performed and the control device detects that although the refrigerant in a hot gas state is flowing to the evaporator, the temperature of the evaporator temperature sensor is lower than a predetermined value, the control device performs control to adjust the flow rate of the refrigerant flowing through the second flow path.

[0022] Furthermore, during the defrosting operation, the three-way valve is in the second state of being open, allowing refrigerant to flow to the hot gas bypass pipe, while the two-way valve is in the closed state; by switching the three-way valve to the first state and running the compressor, the refrigerant discharged from the compressor flows to the condenser.

[0023] Furthermore, the evaporator and fan are installed in the cooling chamber of the refrigerator, and the fan is controlled in conjunction with the operation of the compressor during normal operation. During normal operation, if the compressor is running, the fan also runs; during defrosting and when switching to preparing for defrosting, the fan stops running; when switching from defrosting to normal operation, the fan starts running after a certain delay after the compressor starts running.

[0024] The beneficial effects of the present invention are: the refrigerator of the present invention can more easily reduce the flow rate of refrigerant through the hot gas bypass pipe without complicating the system, thus avoiding a reduction in defrosting capability. Attached Figure Description

[0025] Figure 1 This is a side sectional view of the refrigerator of the present invention.

[0026] Figure 2 This is a circuit diagram of the cooling circuit of the refrigerator of the present invention.

[0027] Figure 3 This is a block diagram of the control system of the refrigerator of the present invention.

[0028] Figure 4 This is a circuit diagram of an example of a cooling circuit commonly used in the prior art.

[0029] Figure 5 This is a timing diagram of the control system of the refrigerator of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Reference Figure 1 This will be used to describe the general features of the refrigerator 1 of the present invention. Figure 1This is a schematic side sectional view of the refrigerator of the present invention. The refrigerator 1 has a refrigerator body 2, a door 3, and a drawer 4. The door 3 is rotatably disposed on the front side of the refrigerator body 2 when placed on a horizontal plane, and the drawer 4 is movable in the front-back direction. The upper and lower parts of the door 3 are engaged with the refrigerator body 2 by hinges provided on at least one of its left and right sides, and can rotate around the hinge axis of the hinge. As described above, the refrigerator 1 of the present invention includes two openable and closable components: the door 3 and the drawer 4. However, the present invention is not limited to this; for example, it may have more drawers, or all opening and closing components may be composed of a door.

[0032] Furthermore, the refrigerator 1 includes an outer shell 5 constituting the exterior of the refrigerator body 2, and an upper inner liner 6 and a lower inner liner 7 constituting the interior storage compartments. In the refrigerator 1 of this embodiment, the upper inner liner 6 constitutes the refrigerator compartment, and the lower inner liner 7 constitutes the freezer compartment. When the door 3 is opened, access to the upper inner liner 6 is possible, and when the drawer 4 is opened, access to the lower inner liner 7 is possible. A storage box (not shown) is installed in the drawer 4, and the storage box is integral with the drawer 4 and can move. The storage box has an opening at the top, through which the user places and stores the lower inner liner 7. Foamed insulation material 8 is filled between the outer shell 5 and each inner liner 6, 7 to insulate each inner liner 6, 7 from the exterior of the refrigerator body 2. In addition, foamed insulation material 8 is also filled between the upper inner liner 6 and the lower inner liner 7.

[0033] like Figure 1 As shown, a cooling chamber 9 is formed at the rear of the lower inner liner 7, and an evaporator 24, serving as a cooling device, is installed in the cooling chamber 9. As will be described later, the evaporator 24 constitutes part of the refrigerator's cooling circuit 20. A fan 10 is provided in the cooling chamber 9, and the fan 10 blows the cold air generated by the evaporator 24 to each inner liner 6, 7 via an air duct 11.

[0034] Air ducts 11 are located at the rear of each inner liner 6 and 7, and cold air generated by the cooling chamber 9 is guided to the front of each inner liner 6 and 7 via vents located on the front surface of the air ducts 11. A damper 12 is provided within the air ducts 11, and the damper 12 is configured to be controlled to open and close by a control device 41 described later. The control device 41 senses the internal temperature of the refrigerator using a refrigerator compartment temperature sensor 14 (not shown) located in the upper inner liner 6, and controls the opening and closing based on the temperature. This allows adjustment of the flow rate of cold air to the upper inner liner 6 (serving as the refrigerator compartment), thereby maintaining a constant internal temperature in the upper inner liner 6 within a temperature range different from that in the lower inner liner 7 (serving as the freezer compartment).

[0035] A machine compartment 13 is provided at the rear and lower part of the refrigerator body 2, and an evaporation dish (not shown) is provided thereon. The evaporation dish collects and evaporates the drainage, which is generated by defrosting the compressor 21, the condenser fan (not shown) that cools the compressor 21 and the condenser 22, and the evaporator 24.

[0036] Figure 2 This is the cooling circuit 20 of the refrigerator 1 of the present invention. The cooling circuit 20 includes a compressor 21, a condenser 22, a capillary tube 23, and an evaporator 24. As described below, the components of the cooling circuit 20 are fluidly connected by pipes in the above order, forming a first flow path for the refrigerant to circulate within the cooling circuit 20. Figure 2 The arrows shown indicate the direction of refrigerant flow. That is, in the cooling circuit 20, for example, in the relationship between the compressor 21 and the evaporator 24 described later, the refrigerant flows from the evaporator 24, which is the upstream side of the flow path, to the compressor 21, which is the downstream side of the flow path, via the suction pipe 28.

[0037] The compressor 21 compresses the gaseous refrigerant, bringing it to a high-temperature, high-pressure state. The compressed refrigerant is then sent to the condenser 22 via a first connecting pipe 25. As described later, the first connecting pipe 25 is equipped with a three-way valve 31 and is divided into a first sub-pipe 25a and a second sub-pipe 25b. The compressor 21 includes an inverter, which, by changing its rotational speed, can adjust the amount of refrigerant discharged per unit time, thereby controlling the cooling capacity of the cooling circuit 20. The compressor 21 is electrically connected to a control device 41 (described later), and its rotational speed is controlled by signals transmitted from the control device 41. The condenser 22 releases the heat from the refrigerant compressed by the compressor 21, causing the refrigerant to condense. The condensed refrigerant is then sent to the capillary tube 23 via a second connecting pipe 26. As described later, the second connecting pipe 26 is equipped with a two-way valve 32 and is divided into a third sub-pipe 26a and a fourth sub-pipe 26b.

[0038] The capillary tube 23 reduces the pressure of the refrigerant condensed by the condenser 22, causing it to expand and its temperature to decrease accordingly. The expanded refrigerant is then sent to the evaporator 24 via pipe 27. The evaporator 24 causes the refrigerant, depressurized by the capillary tube 23, to evaporate and absorb heat. The evaporated refrigerant, now in a gaseous state, is sent to the compressor 21 via suction pipe 28 and compressed again. In this way, the cooling circuit 20 operates. In this embodiment, the capillary tube 23 is connected to the condenser 22 and the evaporator 24 via a fourth sub-pipe 26b and pipe 27, but the fourth sub-pipe 26b and pipe 27 may also be provided within the capillary tube 23.

[0039] The suction pipe 28 is disposed at least partially close to the capillary tube 23, so that heat exchange can be performed between the suction pipe 28 and the capillary tube 23, and the suction pipe 28 allows refrigerant to flow from the evaporator 24 to the compressor 21. Figure 2 The area 29 enclosed by the dashed line represents the general layout of the heat exchange section.

[0040] When the evaporator 24 operates to cool the interior of the refrigerator 1, surrounding water vapor may frost over. To defrost the evaporator 24, the refrigerator 1 of the present invention employs a hot gas defrosting method, using hot gas from the refrigerant compressed by the compressor 21. Therefore, the cooling circuit 20 includes a hot gas bypass pipe 30 connected to a first connecting pipe 25, which connects the downstream compressor 21 and the upstream condenser 22. A three-way valve 31 is provided at this connection point, capable of switching the flow of refrigerant from the compressor 21 via the first sub-pipe 25a to either the condenser 22 (i.e., the second sub-pipe 25b) or the hot gas bypass pipe 30. This allows control over whether the refrigerant flows to the condenser 22 to cool the evaporator 24 or to the hot gas bypass pipe 30 to defrost the evaporator 24. The hot gas bypass pipe 30 is connected to a pipe that connects the downstream capillary tube 23 and the upstream evaporator 24.

[0041] The hot gas bypass pipe 30 forms a second flow path for the refrigerant to flow through the compressor 21-first connecting pipe 25-hot gas bypass pipe 30-pipe 27-evaporator 24. This second flow path is different from the flow path of the refrigerant through the first flow path mentioned above, which is compressor 21-first connecting pipe 25-condenser 23-second connecting pipe 26-capillary tube 23-pipe 27-evaporator 24.

[0042] The three-way valve 31 is connected to the control device 41 described later. Based on predetermined conditions, the control device 41 controls the switching of the refrigerant flow path. The control device 41 controls the three-way valve 31 so that the refrigerant flows to the condenser 22 (i.e., the second sub-pipe 25b) during normal operation and to the hot gas bypass pipe 30 during defrosting operation. The refrigerant is discharged from the compressor 21 via the first sub-pipe 25a.

[0043] In this specification, the state in which the refrigerator 1 operates normally (i.e., the state in which it operates to cool the interior of the refrigerator or to maintain the interior temperature) is appropriately referred to as "normal operation". Furthermore, the state in which the refrigerator 1 operates to defrost the evaporator 24 (i.e., the state in which the refrigerator operates to open the three-way valve 31, allowing refrigerant to flow from the three-way valve 31 to the hot gas bypass pipe 30, thus allowing hot gas to flow to the evaporator 24) is appropriately referred to as "defrosting operation".

[0044] In this embodiment, the cooling circuit 20 of the refrigerator 1 includes a two-way valve 32 in the second connecting pipe 26, which fluidly connects the condenser 22 and the capillary tube 23. The two-way valve 32 is connected to a control device 41. The control device 41 controls the opening and closing of the two-way valve 32 based on the refrigerant discharged from the condenser 22. By closing the two-way valve 32, the flow of refrigerant to the fourth sub-pipe 26b can be cut off.

[0045] Figure 3 This is a structural block diagram of the control system 40 of the refrigerator 1 of the present invention. The control system 40 of the refrigerator 1 in this embodiment includes a control device 41 for controlling various devices. The control device 41 may be composed of multiple control units. For example, the control device 41 is composed of a control unit (not shown) and a storage unit (not shown).

[0046] The control unit includes a general-purpose processor, such as a CPU or MPU, that executes programs to achieve predetermined functions. For example, the control unit calls and executes arithmetic programs stored in the storage unit to perform various processes in the control device 41 and transmit signals to various components. The control unit is not limited to achieving predetermined functions through the cooperation of hardware and software; it can also be a hardware circuit specifically designed to achieve predetermined functions. That is, in addition to CPUs and MPUs, the control unit can also be implemented by various processors such as GPUs, FPGAs, DSPs, and ASICs. Such a control unit can be constructed, for example, as a signal processing circuit that is a semiconductor integrated circuit.

[0047] The storage unit is a recording medium capable of recording various types of information. The storage unit is implemented using memory such as DRAM, SRAM, flash memory, HDD, SSD, other storage devices, or appropriate combinations thereof. The storage unit can store, for example, temperatures obtained from the refrigerator compartment temperature sensor 14 and the evaporator temperature sensor 15, and pressure values ​​obtained from the aforementioned pressure sensors. Furthermore, it can store programs for controlling various components (compressor 21, three-way valve 31, two-way valve 32, fan 10, damper 12, etc.) based on these temperatures and pressures. It can also store control programs related to routine operation and defrosting operations, as described later. Information can also be directly transmitted and received between components via the control unit without going through the storage unit.

[0048] As described above, the compressor 21, three-way valve 31, and two-way valve 32 are electrically connected to the control device 41. Furthermore, the control device 41 is also electrically connected to the fan 10, damper 12, condenser fan, refrigerator compartment temperature sensor 14, and evaporator temperature sensor 15. Other temperature sensors may also be installed (e.g., a freezer compartment temperature sensor installed in the lower inner liner 7 constituting the freezer compartment), and these temperature sensors are electrically connected to the control device 41. Based on signals from the refrigerator compartment temperature sensor 14, the control device 41 controls the temperature of the refrigerator compartment and freezer compartment to maintain a predetermined temperature.

[0049] The control device 41 can initiate defrosting under any conditions. For example, a defrost switch (not shown) can be provided in the refrigerator 1, and the defrost operation can be initiated when the control device 41 detects that the user has turned on the switch. Instead of a defrost switch, or in addition to a defrost switch, a timer can be set, configured to initiate defrosting when a period set by the user in the timer has elapsed. Furthermore, an elapsed time detection function can be provided in the control device 41, configured to initiate defrosting when the elapsed time since the last defrost operation exceeds a predetermined time. A sensor capable of detecting the opening and closing of at least one of the doors 3 or drawers 4 can also be provided, configured to detect the number of opening and closing operations, and initiate defrosting when the number exceeds a predetermined threshold.

[0050] By providing a three-way valve 31 and a two-way valve 32, as in the cooling circuit 20 of the refrigerator 1 of this embodiment, the defrosting capacity of the defrosting operation when the refrigerant flows to the hot gas bypass pipe 30 can be prevented from decreasing. An operating example of the cooling circuit 20 will be described below.

[0051] During normal operation of the refrigerator 1, the three-way valve 31 is open to allow refrigerant to flow to the condenser 22. This state of the three-way valve 31 will be referred to as the "first state" below. Furthermore, the state in which the three-way valve 31 is open to allow refrigerant to flow to the hot gas bypass pipe 30 will be referred to as the "second state" below. The two-way valve 32 is configured to open and close according to the operation of the compressor 21, controlled by the control device 41. Therefore, during normal operation, the two-way valve 32 is open when the compressor 21 compresses and discharges refrigerant. Furthermore, in this embodiment, the two-way valve 32 is closed when the compressor 21 stops. However, the invention is not limited to this; the two-way valve may also remain open during normal operation when the compressor 21 is stopped.

[0052] When the operation of the cooling circuit 20 is switched from normal operation to defrosting, the control device 41 first maintains the three-way valve 31 in the first state while simultaneously closing the two-way valve 32. This prevents refrigerant from flowing downstream of the fourth sub-pipe 26b. In this state, the control device 41 operates the compressor 21, discharging refrigerant into the condenser 22. This allows refrigerant to be stored in the condenser 22 and the second sub-pipe 25b, and the third sub-pipe 26a (hereinafter, for convenience, referred to as storing refrigerant in the condenser 22). The rotational speed of the compressor 21 can be adjusted to increase or decrease the discharge rate. For example, increasing the discharge rate from the compressor 21 allows for faster refrigerant storage in the condenser 22, and also allows for the storage of more refrigerant.

[0053] After refrigerant has accumulated in the condenser 22, the control device 41 switches the three-way valve 31 to a second state to perform a defrosting operation. Therefore, refrigerant (hot gas) is discharged from the compressor 21 to the hot gas bypass pipe 30. At this time, the two-way valve 32 remains closed. The control device 41 can perform the above-mentioned switching of the three-way valve 31 by detecting, for example, that the refrigerant has accumulated in the condenser 22 for a predetermined time. Alternatively, the switching can be performed by detecting the load on the compressor 21, which is included in the compressor 21, by measuring the speed and current of the motor. Alternatively, a pressure sensor can be installed in the flow path from the compressor 21 to the condenser 22 or inside the condenser 22, configured to detect the refrigerant pressure at that location. When the pressure sensor detects that the pressure at that location has become above a predetermined threshold, the switching is performed.

[0054] By controlling the three-way valve 31 and the two-way valve 32 in this way, the amount of refrigerant in the cooling circuit 20 during defrosting can be reduced. During normal operation, the cooling circuit 20, as a first flow path, is, as described above, a path where refrigerant flows from the compressor 21 through the condenser 22 and capillary tube 23 into the evaporator 24. Conversely, during defrosting, the cooling circuit 20, as a second flow path, is, as described above, a path where refrigerant flows from the compressor 21 through the hot gas bypass pipe 30 into the evaporator 24. Thus, the second flow path involves fewer components than the first flow path. Furthermore, the condenser 22 discharges heat from the refrigerant compressed by the compressor 21, and therefore typically forms a longer flow path. Therefore, the overall length of the second flow path is shorter than the first flow path. Consequently, the amount of refrigerant may be excessive relative to the length of the flow path.

[0055] If too much refrigerant is added during the defrosting process, the hot refrigerant can easily condense into a liquid state (i.e., hot gas can easily return to liquid form). If the refrigerant becomes liquid and flows into the compressor 21, the reliability of the compressor 21 may decrease, for example, its performance may be reduced. In addition, the temperature of the suction pipe 28 may drop, resulting in condensation.

[0056] Furthermore, when the amount of refrigerant in the pipeline increases, resulting in liquid refrigerant within the pipeline, the space available for hot gaseous refrigerant to pass through the pipeline narrows. As a result, the refrigerant flow rate and pressure loss increase, and furthermore, the hot gaseous refrigerant is more likely to condense into a liquid state.

[0057] However, as in the cooling circuit 20 of the refrigerator 1 of this embodiment, by reducing the amount of refrigerant flowing in the cooling circuit during the defrosting operation before the defrosting operation is performed, the possibility of refrigerant condensation in a hot gas state is reduced. Therefore, the reduction in defrosting capacity can be suppressed.

[0058] Furthermore, in the cooling circuit 20 of the refrigerator 1 of the present invention, an evaporator temperature sensor 15 is provided on the evaporator 24. The evaporator temperature sensor 15 is installed, for example, in the part from which refrigerant is discharged from the evaporator 24. The evaporator temperature sensor 15 detects the temperature of the evaporator 24 and transmits it to the control device 41. Thus, the control device 41 is able to detect whether the predetermined defrosting capability can be achieved during the defrosting operation.

[0059] If the temperature detected by the evaporator temperature sensor 15 is lower than a predetermined value during the defrosting operation, the evaporator 24 may not defrost sufficiently. In this case, one possible reason is that, as described above, the defrosting capacity is reduced due to refrigerant condensation caused by an excess of refrigerant. Therefore, it is preferable to reduce the amount of refrigerant flowing through the second flow path during the defrosting operation.

[0060] Therefore, during defrosting, if the control device 41 detects that although the refrigerant in a hot gas state is flowing towards the evaporator 24, but the temperature of the evaporator temperature sensor 15 is lower than a predetermined value, it will control the flow of refrigerant through the second flow path to adjust the flow rate. Specifically, for example, the refrigerant flow rate can be adjusted by switching the three-way valve 31.

[0061] During defrosting, as described above, the three-way valve 31 is in the second state, and the two-way valve 32 is in the closed state. By switching the three-way valve 31 to the first state and running the compressor, the refrigerant discharged from the compressor 21 flows to the condenser 22. Since the two-way valve 32 is in the closed state, the refrigerant cannot flow downstream of the third sub-pipe 26a and accumulates in the condenser 22. Then, by switching the three-way valve 31 to the second state, the flow rate of refrigerant flowing through the second flow path can be reduced. As a result, the condensation of hot refrigerant in the pipeline can be suppressed, thereby suppressing the reduction in defrosting capacity.

[0062] Figure 4 The cooling circuit 20a shown is an example of a simplified cooling circuit in a conventional refrigerator that uses hot gas defrosting. Components identical to those in cooling circuit 20 are labeled with the same reference numerals. Figure 2 and Figure 4 A comparison clearly shows that the difference between the cooling circuit 20a of a conventional refrigerator and the cooling circuit 20 is that the latter does not include the two-way valve 32. As described above, the cooling circuit 20 of the refrigerator 1 in this embodiment can reduce the flow rate of refrigerant through the second flow path simply by adding a two-way valve 32 to the cooling circuit 20a of a conventional refrigerator and increasing the control of the two-way valve 32. Therefore, the condensation of hot refrigerant in the pipeline during defrosting can be easily avoided, thereby suppressing the reduction of defrosting capacity.

[0063] Furthermore, besides excessive refrigerant, other reasons may contribute to the reduced defrosting capacity. For example, consider the case where the inner diameter 30a of the hot gas bypass pipe 30 is smaller than the inner diameter 21a of the discharge pipe from the compressor 21. In this case, the refrigerant flow velocity within the pipe increases, pressure loss increases, and the hot refrigerant is more prone to condensation. Therefore, by setting the inner diameter 30a of the hot gas bypass pipe 30 to be larger than the inner diameter 21a of the compressor 21, the pressure loss during refrigerant flow can be reduced, thereby preventing refrigerant condensation. Furthermore, by increasing the inner diameter 30a of the hot gas bypass pipe 30, the circuit volume of the cooling circuit 20 used during defrosting, including the second flow path, can be increased.

[0064] Furthermore, the opening diameter 31a (hereinafter appropriately referred to as the inner diameter 31a of the three-way valve 31) is defined as the smallest portion of the space through which the refrigerant flows within the three-way valve 31. The size of this opening diameter 31a also affects the reduction in defrosting capacity. When the inner diameter 31a of the three-way valve 31 is smaller than the inner diameter 21a of the discharge pipe from the compressor 21, the flow rate of the refrigerant through the three-way valve 31 increases, the pressure loss increases, and the hot refrigerant is more prone to condensation. Therefore, by setting the inner diameter 31a of the three-way valve 31 to be larger than the inner diameter 21a of the discharge pipe of the compressor 21, the pressure loss during refrigerant flow can be reduced, thereby suppressing refrigerant condensation.

[0065] Table 1 shows an example of the change in temperature T of the evaporator 24 caused by defrosting operation when the inner diameter 30a of the hot gas bypass pipe 30 and the inner diameter 31a of the three-way valve 31 are changed relative to the inner diameter 21a of the discharge pipe of the compressor 21. This temperature T is measured by a temperature sensor (not shown) installed at the lower part of the evaporator 24, a location where the temperature is difficult to rise.

[0066] Table 1

[0067]

[0068] In the above example, the discharge pipe of compressor 21 with an inner diameter of φ4.76 (i.e., 4.76 mm) was used, and the experiment was conducted under these conditions at an ambient temperature of 16°C. In this example, hot gas bypass pipes 30 with inner diameters of φ4 and φ6 were used. Furthermore, three-way valves 31 with inner diameters of φ2, φ4, and φ6 were used.

[0069] As shown in Table 1, when the inner diameter 30a of the hot gas bypass pipe 30 is φ4, if the inner diameter 31a of the three-way valve 31 is changed to φ2, φ4, or φ6, the temperatures T at the end of defrosting, measured by the temperature sensor installed on the evaporator 24, are -0.4℃, 5.4℃, and 5.8℃, respectively. Thus, according to Table 1, by making the inner diameter 31a of the three-way valve 31 larger than the inner diameter 21a of the discharge pipe of the compressor 21, the pressure loss during refrigerant flow can be reduced, thereby avoiding a decrease in defrosting capacity.

[0070] Furthermore, when the inner diameter 31a of the three-way valve 31 is φ6, if the inner diameter 30a of the hot gas bypass pipe 30 is changed to φ4 or φ6, the temperatures at the end of defrosting, measured by the temperature sensor installed on the evaporator 24, are 5.8°C and 7.2°C, respectively. Thus, as shown in Table 1, by making the inner diameter 30a of the hot gas bypass pipe 30 larger than the inner diameter 21a of the compressor 21's discharge pipe, the pressure loss during refrigerant flow can be reduced, thereby preventing a decrease in defrosting capacity.

[0071] Figure 5 This is a timing diagram showing the operation of the cooling circuit 20 and other cooling devices of the present invention. Figure 5 In the diagram, (a), (b), (c), (d), (e), and (f) illustrate the operating sequence of the compressor 21, two-way valve 32, three-way valve 31, fan 10, damper 12, and condenser fan, respectively. The control device 41 can control each device by transmitting the control signals described below.

[0072] Figure 5 (a) shows the rotational speed of compressor 21. “OFF” means compressor 21 is not working. “LOW” means the motor of compressor 21 is rotating at a low speed. “HIGH” means the motor of compressor 21 is rotating at a high speed.

[0073] exist Figure 5 In (b), "ON" means that the two-way valve 32 is open. In addition, "OFF" means that it is closed.

[0074] exist Figure 5 In (c), "ON" means that the three-way valve 31 is in the second state. In addition, "OFF" means that it is in the first state.

[0075] exist Figure 5 In (d) and (f), "ON" means that each fan is running. In addition, "OFF" means that each fan is stopped.

[0076] exist Figure 5 In (e), "ON" means that the damper 12 is open so that cold air from the cooling chamber 9 can be blown above the air duct 11. In addition, "OFF" means that the damper 12 is closed.

[0077] Figure 5 Period A is the period of normal operation. During normal operation, compressor 21 and two-way valve 32 operate in conjunction. When compressor 21 is running, two-way valve 32 is in the open state. Furthermore, when compressor 21 stops, two-way valve 32 is in the closed state. In contrast, three-way valve 31 is in the first state in every situation.

[0078] Period B is the preparation phase before defrosting, during which refrigerant is stored in the condenser 32 (i.e., a temporary pump-down). During Period B, the compressor 21 continues to operate, but the two-way valve 32 is switched to the closed state. Furthermore, the three-way valve 31 is in its first state as during normal operation. Figure 5 In the timing diagram shown, the compressor 21 operates at the same speed as during normal operation, but it can also be set to increase or decrease the speed mentioned above.

[0079] Period C is the period during which defrosting occurs. The compressor 21 operates in the same manner as during periods A and B. Furthermore, the two-way valve 32 is in the closed state. The three-way valve 31 is switched to its second state, allowing refrigerant to flow to the hot gas bypass pipe 30. ​ In the timing diagram shown, the speed of the compressor 21 is increased compared to normal operation, but it can be the same as the normal operation speed or decreased compared to normal operation speed.

[0080] Period D is a certain period after the defrosting operation ends. After the defrosting operation ends, the compressor 21 stops running, and the three-way valve 31 switches to the first state. After a certain period, the compressor 21 is restarted for normal operation, and the two-way valve 32 is switched to the open state. At this time, because the high-temperature refrigerant flows in the evaporator 24 during the defrosting operation, the temperature of the evaporator 24 is higher than usual. Therefore, in order to lower the temperature of the evaporator 24, after a certain period, the fan 10, etc., is run, and normal operation begins.

[0081] Basically, the fan 10 is controlled in conjunction with the operation of the compressor 21 during normal operation. During normal operation, if the compressor 21 is running, the fan 10 also runs. During defrosting operation and when switching to preparation for defrosting operation, the fan 10 stops running. Furthermore, when transitioning from defrosting operation to normal operation, after the compressor 21 starts running, the evaporator 24, which is heated during defrosting, needs to be cooled; therefore, the fan 10 starts running after a certain delay from when the compressor 21 starts running.

[0082] The opening and closing of the damper 12 is basically controlled in conjunction with the operation of the fan 10. Furthermore, although not shown, the damper 12 can be closed even when the fan 10 is running, so that the temperature inside the upper inner liner 6 is maintained constant based on the temperature detected by the refrigerator compartment temperature sensor, which is installed inside the upper inner liner 6, which serves as the refrigerator compartment.

[0083] The condenser fan operates in conjunction with the compressor 21.

[0084] In this way, the control device 41 controls the compressor 21, the two-way valve 32, and the three-way valve 31, thereby preventing a reduction in defrosting capacity through the cooling circuit of the refrigerator 1 in this embodiment.

[0085] This invention is not limited to the illustrated embodiments, and various improvements and design changes can be made without departing from the spirit of the invention.

[0086] Industrial availability

[0087] As described above, according to the present invention, a refrigerator 1 can be provided that can easily reduce the flow rate of refrigerant through the hot gas bypass pipe without the need for a complex system, thereby avoiding a reduction in defrosting capability. Therefore, it can be preferably used in the industrial field of such refrigerators.

[0088] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A refrigerator, characterized in that, The device includes a cooling circuit having a first flow path for circulating refrigerant, connected in the order of a compressor, a condenser, a capillary tube, and an evaporator. The compressor compresses the refrigerant from the evaporator, the condenser condenses the refrigerant from the compressor, the capillary tube expands the refrigerant from the condenser, and the evaporator evaporates the refrigerant from the capillary tube. The cooling circuit also includes a suction pipe for flowing refrigerant from the evaporator to the compressor, the suction pipe being at least partially adjacent to the capillary tube to allow heat exchange between the suction pipe and the capillary tube. The cooling circuit includes: A hot gas bypass pipe is configured to form a second flow path that allows the refrigerant compressed by the compressor to flow from the compressor to the evaporator, wherein the inner diameter of the hot gas bypass pipe is larger than the inner diameter of the compressor's discharge pipe. A three-way valve is disposed in the first flow path between the compressor and the condenser, and connected to the hot gas bypass pipe. The inner diameter of the three-way valve is larger than the inner diameter of the compressor's discharge pipe. A two-way valve is disposed in the first flow path between the condenser and the capillary tube. The three-way valve allows the refrigerant discharged from the compressor to flow into the condenser or the hot gas bypass pipe. The two-way valve can shut off the flow of refrigerant discharged from the condenser by closing it; The refrigerator has a control device that switches the cooling circuit between normal operation (cooling the evaporator) and defrosting operation (defrosting the evaporator). When switching the cooling circuit from normal operation to defrosting operation, the control device first maintains the three-way valve in the first state and simultaneously changes the two-way valve to the closed state. In this state, the control device runs the compressor to discharge refrigerant into the condenser. After refrigerant has accumulated in the condenser, the control device switches the three-way valve to the second state to perform the defrosting operation.

2. The refrigerator according to claim 1, characterized in that, The control device can control which of the three-way valves allows the fluid to flow into the condenser and the hot gas bypass pipe, and can also control the opening and closing of the two-way valve. When switching from the normal operation to the defrosting operation, the control device controls the flow as follows: the three-way valve allows the refrigerant to flow into the condenser and closes the two-way valve, thereby discharging the refrigerant into the condenser through the compressor. Afterward, the three-way valve allows the refrigerant to flow into the hot gas bypass pipe.

3. The refrigerator according to claim 2, characterized in that, The evaporator is equipped with a temperature sensor. During the defrosting operation, the control device controls the three-way valve and the two-way valve based on the temperature measured by the temperature sensor to adjust the amount of refrigerant.

4. The refrigerator according to claim 3, characterized in that, The refrigerant is discharged from the compressor through the discharge pipe.

5. The refrigerator according to claim 3, characterized in that, Compressed refrigerant is sent to the condenser through a first connecting pipe, which is equipped with the three-way valve and is divided into a first sub-pipe and a second sub-pipe.

6. The refrigerator according to claim 5, characterized in that, The condensed refrigerant is sent to the capillary tube through a second connecting pipe, which is equipped with the two-way valve and is divided into a third sub-pipe and a fourth sub-pipe.

7. The refrigerator according to claim 3, characterized in that, When the defrosting operation is performed, if the control device detects that although the refrigerant in a hot gas state is flowing to the evaporator, but the temperature of the evaporator temperature sensor is lower than a predetermined value, it will control the flow rate of the refrigerant flowing through the second flow path to adjust the flow rate of the refrigerant.

8. The refrigerator according to claim 3, characterized in that, During defrosting, the three-way valve is in the second state, which allows refrigerant to flow to the hot gas bypass pipe, and the two-way valve is in the closed state; by switching the three-way valve to the first state and running the compressor, the refrigerant discharged from the compressor flows to the condenser.

9. The refrigerator according to claim 3, characterized in that, The evaporator and fan are installed in the cooling chamber of the refrigerator. The fan is controlled in conjunction with the operation of the compressor during normal operation. During normal operation, if the compressor is running, the fan also runs. During defrosting and when switching to preparing for defrosting, the fan stops running. When switching from defrosting to normal operation, the fan starts running after a certain delay after the compressor starts running.

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