Freezing-refrigeration unit and refrigerator-freezer having the same

Abstract

To obtain a freezing-refrigeration unit which detects leakage of a refrigerant early regardless of a type of a phenomenon of the refrigerant leakage occurring in an evaporator, and to obtain a refrigerator-freezer having the freezing-refrigeration unit.SOLUTION: A freezing-refrigeration unit is disposed on a housing chamber in which objects to be cooled are housed and includes: a cooling chamber communicating with the housing chamber through an opening formed on a ceiling plate of the housing chamber; an evaporator provided in the cooling chamber; a blower for the evaporator which suctions air from the housing chamber and sends air to the evaporator; a partition plate which partitions the opening into an air inlet through which air is suctioned from the housing chamber into the cooling chamber and an air outlet through which cool air is blown out from the cooling chamber to the housing chamber; a duct which communicates with the cooling chamber through the air outlet and guides the cool air flowing from the air outlet so that the cool air is blown out to the housing chamber along the ceiling plate; and a refrigerant leakage detection sensor which is provided in the duct and detects a refrigerant contained in the cool air.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a freezer-refrigerator unit including a refrigerant circuit and a refrigerator-freezer having the same. [Background technology]

[0002] Conventionally, built-in refrigeration and freezing equipment with doors, such as commercial refrigerators and prefabricated refrigerators, are equipped with refrigeration and freezing units that use R404A or R410A as a refrigerant. In recent years, from the viewpoint of preventing global warming, it is desired to switch from fluorocarbon refrigerants such as R404A and R410A, which have high global warming potential (GWP), to natural refrigerants such as R290 (propane) and R600a, which have low GWP. The GWP of R404A is 3920, and the GWP of R410A is 2090. It is also desired to reduce power consumption and save energy in refrigeration and freezing equipment in order to reduce carbon dioxide emissions.

[0003] The amount of refrigerant charged in commercial refrigerators and commercial prefabricated refrigerators is greater than that in household refrigerators. In addition, the kitchen environment in which commercial refrigerators are installed is prone to open flames that can become ignition sources. For this reason, careful consideration is being given to the application of flammable natural refrigerants. In the case of a refrigeration cycle device that uses a flammable refrigerant, when the refrigerant leaks, the condenser blower is operated in the machine room where the compressor and condenser are installed to ensure a certain amount of airflow, thereby dispersing the refrigerant and preventing the formation of a flammable area. However, another measure is required to prevent refrigerant leakage from the evaporator.

[0004] The Japan Refrigeration and Air Conditioning Industry Association (JRA) standard "JRA 4078:2021" describes the safety mechanism requirements for refrigerant leakage from built-in refrigeration equipment using flammable refrigerants. This standard states that if a built-in refrigeration equipment is equipped with a refrigerant leakage detection function and an internal refrigerant leakage cut-off device, it is considered that no flammable area is generated due to leakage inside the equipment. The internal refrigerant leakage cut-off device cuts off the flow of refrigerant so that the refrigerant concentration inside the equipment does not exceed the lower flammability limit (LFL). For example, if the refrigerant is R290, the LFL is 21,000 ppm. This standard also states that an additional function that satisfies the internal refrigerant leakage warning function may be installed.

[0005] Conventionally, when R290 is used as the refrigerant, a refrigeration unit has been proposed that detects refrigerant leakage from a refrigerant circuit including an evaporator (see, for example, Patent Document 1). The refrigeration unit disclosed in Patent Document 1 determines that a refrigerant leak has occurred when the temperature detected by an evaporation temperature sensor attached to the evaporator falls to or below approximately -40°C, which is the boiling point of R290. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2006-10126 A Summary of the Invention [Problem to be solved by the invention]

[0007] Refrigerant leakage includes phenomena such as a burst leak, a rapid leak, and a micro leak. It is said that a micro leak accounts for about 98% of refrigerant leakage. The cause of a micro leak is, for example, a pinhole formed in the refrigerant piping. The refrigerant leakage rate of a micro leak is about 0.42 kg / h, which is slower than the refrigerant leakage rates of other phenomena. When the refrigerant leakage is a burst leak or a rapid leak, the evaporation temperature drops relatively quickly, but when the refrigerant leakage is a micro leak, the rate at which the evaporation temperature drops is slower.

[0008] The freezing and refrigeration unit disclosed in Patent Document 1 determines that there is a refrigerant leak when the temperature detected by the evaporation temperature sensor falls to approximately -40°C or lower, but if the refrigerant leak is a small leak, the evaporation temperature drops slowly and it takes time to determine that there is a refrigerant leak. In this case, there is a risk that the concentration of the refrigerant in the refrigerator will exceed the LFL due to the refrigerant leak.

[0009] The present disclosure has been made to solve the above-mentioned problems, and provides a freezer-refrigerator unit that detects refrigerant leakage at an early stage regardless of the type of refrigerant leakage phenomenon that occurs in the evaporator, and a freezer-refrigerator having the same. [Means for solving the problem]

[0010] The freezing and refrigeration unit of the present disclosure is a freezing and refrigeration unit placed above a storage chamber in which an object to be cooled is stored, and includes a cooling chamber communicating with the storage chamber through an opening formed in a ceiling panel of the storage chamber, an evaporator provided in the cooling chamber, an evaporator blower that draws in air from the storage chamber and sends the air to the evaporator, a partition plate that divides the opening into an intake port through which air is sucked from the storage chamber to the cooling chamber and an outlet port through which cold air is blown out from the cooling chamber into the storage chamber, a duct that communicates with the cooling chamber through the outlet port and guides the cold air flowing out from the outlet port so that it is blown along the ceiling panel into the storage chamber, and a refrigerant leakage detection sensor provided in the duct for detecting refrigerant contained in the cold air.

[0011] A freezer-refrigerator according to the present disclosure includes the freezer-refrigerator unit described above and a storage chamber for storing an object to be cooled. Effect of the Invention

[0012] According to the present disclosure, when refrigerant leaks from the evaporator, the refrigerant leaking from the evaporator is carried by the airflow generated by the evaporator blower and flows into the duct. Since the refrigerant leakage detection sensor is disposed in the duct, even if the refrigerant leaking from the evaporator is due to a microleak phenomenon, the refrigerant leakage is detected at an early stage by the refrigerant leakage detection sensor. [Brief description of the drawings]

[0013] [Figure 1] 1 is an external perspective view showing an example of a refrigerator having a freezing and refrigerating unit according to embodiment 1. FIG. [Diagram 2] FIG. 1 is a refrigerant circuit diagram of a refrigeration and freezing unit according to a first embodiment. [Diagram 3] FIG. 2 is an external top view of the refrigeration and freezing unit shown in FIG. [Figure 4] 2 is a schematic side view of the refrigerator-freezer shown in FIG. 1 as seen from the side. [Diagram 5] FIG. 5 is an external perspective view showing one configuration example of the duct shown in FIG. 4. [Figure 6] 5 is an external perspective view showing one configuration example of the partition plate shown in FIG. 4. [Figure 7] 2 is a block diagram for explaining control executed by a control device in the refrigeration and freezing unit according to the first embodiment. FIG. [Figure 8] 4 is a flow chart showing an example of an operation procedure of the refrigeration and freezing unit according to the first embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An embodiment of the refrigeration / freezing unit of the present disclosure will be described with reference to the drawings. In this embodiment, the refrigeration / freezing unit will be described as being installed in a commercial refrigerator / freezer and a prefabricated refrigerator / freezer for commercial use. For convenience of explanation, three coordinate axes (X-axis, Y-axis, and Z-axis) for defining directions are shown in some of the drawings to be referred to. The direction opposite to the Z-axis arrow is the direction of gravity.

[0015] Embodiment 1 The configuration of the freezing and refrigerating unit of the present embodiment 1 will be described. FIG. 1 is an external perspective view showing an example of a freezing and refrigerating unit having the freezing and refrigerating unit according to the embodiment 1. The freezing and refrigerating unit 50 has a freezing and refrigerating unit 1 and a storage chamber 55 in which an object to be cooled is stored. The freezing and refrigerating unit 1 is provided above the storage chamber 55. In the present embodiment 1, the freezing and refrigerating unit 50 will be described as being, for example, a commercial freezing and refrigerating unit, but the freezing and refrigerating unit 50 is not limited to a commercial freezing and refrigerating unit.

[0016] Storage chamber 55 is a space surrounded by ceiling board 51, four side wall boards 52, and floor board 53. Of the four side wall boards 52, one side wall board 52 is provided with a door 54. Door 54 is opened and closed by an operator when the operator places an object to be cooled in storage chamber 55 and when the operator removes the object to be cooled from storage chamber 55.

[0017] Fig. 2 is a refrigerant circuit diagram of the refrigeration / refrigeration unit according to the first embodiment. As shown in Fig. 2, the refrigeration / refrigeration unit 1 includes a compressor 3, a condenser 4, an expansion valve 10, an evaporator 11, a condenser blower 5, an evaporator blower 12, a refrigerant leakage detection sensor 20, a temperature sensor 24, and a control device 40. The compressor 3, the condenser 4, the expansion valve 10, and the evaporator 11 are connected via a refrigerant pipe 31 to form a refrigerant circuit 30. The temperature sensor 24 detects a room temperature Tr, which is the temperature of the air in the accommodation chamber 55. The temperature sensor 24 is, for example, a thermistor.

[0018] A liquid solenoid valve 9 is provided in the refrigerant pipe 31 between the condenser 4 and the expansion valve 10. The liquid solenoid valve 9 serves to adjust the flow rate of liquid refrigerant flowing from the condenser 4 to the expansion valve 10. When the liquid solenoid valve 9 is in a closed state, it also serves to block the liquid refrigerant flowing from the condenser 4 to the expansion valve 10. A bypass circuit 25 is provided to connect a first relay point between the refrigerant discharge port of the compressor 3 and the condenser 4, and a second relay point between the expansion valve 10 and the evaporator 11. A hot gas solenoid valve 8 is provided in the bypass circuit 25. The hot gas solenoid valve 8 serves to adjust the flow rate of high-temperature, high-pressure gas refrigerant discharged from the compressor 3.

[0019] A check valve 22 is provided in the refrigerant pipe 31 between the evaporator 11 and the compressor 3. The check valve 22 allows the refrigerant to flow in only one direction through the refrigerant pipe 31. In the first embodiment, the check valve 22 allows the refrigerant to flow from the evaporator 11 to the compressor 3, but prohibits the refrigerant from flowing from the compressor 3 to the evaporator 11. By providing the check valve 22 at the refrigerant suction port of the compressor 3, it is possible to prevent the refrigerant from flowing from the compressor 3 to the evaporator 11 even if the refrigerant pressure on the evaporator 11 side becomes lower than the refrigerant pressure on the compressor 3 side when the operation of the compressor 3 stops.

[0020] A high pressure switch 21 is provided in the refrigerant piping 31 at the refrigerant discharge port of the compressor 3. The high pressure switch 21 transmits a stop instruction signal, which is a signal instructing the compressor 3 to stop, to the control device 40 when the pressure of the refrigerant discharged from the compressor 3 becomes equal to or higher than a predetermined high pressure threshold.

[0021] Fig. 3 is an external top view of the refrigerator / freezer unit shown in Fig. 1. Fig. 4 is a schematic side view of the refrigerator / freezer shown in Fig. 1. In Fig. 4, the direction of air flow is indicated by white arrows.

[0022] As shown in Fig. 3, the refrigeration / freezing unit 1 has a unit base 2 that serves as a stand. On the unit base 2, a compressor 3, a condenser 4, a condenser blower 5, a reactor box 6, a hot gas solenoid valve 8, a liquid solenoid valve 9, an expansion valve 10, a heat insulating box 13, and a control box 7 are arranged. Also, on the unit base 2, a power conversion circuit (not shown) that converts AC voltage supplied from an external power supply system into DC voltage, and an inverter circuit (not shown) that supplies three-phase AC current to the compressor 3 based on the DC voltage supplied from the power conversion circuit are provided. The reactor box 6 has a reactor (not shown), and the reactor serves to reduce harmonics generated in the inverter circuit (not shown).

[0023] A cooling chamber 23 that houses the evaporator 11 and the evaporator blower 12 is formed in the heat-insulating box 13. The top and sides of the cooling chamber 23 are covered by the heat-insulating box 13. The evaporator 11 and the evaporator blower 12 are supported on the unit base 2 by support plates 14 and 15. A drain pan 16 is provided below the evaporator 11. The control box 7 houses the control device 40 shown in FIG. 2. In FIG. 3, the refrigerant piping 31 shown in FIG. 2 is omitted from the drawing.

[0024] Each of the devices, namely, the compressor 3, the condenser blower 5, the hot gas solenoid valve 8, the liquid solenoid valve 9, the expansion valve 10, and the evaporator blower 12, is communicatively connected to the control device 40 via signal lines not shown in the figure. Each of the detection means, namely, the refrigerant leakage detection sensor 20, the temperature sensor 24, and the high pressure switch 21, is communicatively connected to the control device 40 via signal lines not shown in the figure. Each of the devices, such as the compressor 3, and each of the detection means, such as the refrigerant leakage detection sensor 20, may be communicatively connected to the control device 40 by wireless communication means, not limited to wired communication.

[0025] The compressor 3 draws in the refrigerant, compresses the drawn refrigerant, and discharges a high-temperature, high-pressure gas refrigerant. The compressor 3 is, for example, an inverter compressor whose capacity can be changed. The condenser 4 is a heat exchanger that exchanges heat between the refrigerant discharged from the compressor 3 and the air around the condenser 4, and condenses the refrigerant by dissipating heat to the refrigerant. The condenser 4 is, for example, a fin-and-tube type heat exchanger having a heat transfer tube and a plurality of heat dissipation fins. In FIG. 3, the fins are omitted from the drawing. The condenser blower 5 diffuses the air heated in the condenser 4 and supplies the condenser 4 with unheated air. This promotes heat exchange between the air and the refrigerant in the condenser 4.

[0026] In addition, the condenser blower 5 operates while the refrigeration / freezing unit 1 is operating. Specifically, the condenser blower 5 operates to ensure a predetermined air volume in any operation mode, including when the operation mode of the refrigeration / freezing unit 1 is defrosting operation. As a result, when refrigerant leaks from the compressor 3, the condenser 4, and the refrigerant piping 31 connecting these devices, the leaked refrigerant is agitated, preventing the formation of a flammable region.

[0027] The expansion valve 10 reduces the pressure of the refrigerant condensed in the condenser 4 to expand it. The expansion valve 10 is, for example, an electronic expansion valve. In the present embodiment 1, the case where the expansion valve 10 is an electronic expansion valve will be described. When the expansion valve 10 is in a closed state, it blocks the flow of the refrigerant. The evaporator 11 is a heat exchanger that exchanges heat between the refrigerant reduced in pressure by the expansion valve 10 and the air in the cooling chamber 23, and causes the refrigerant to absorb heat and evaporate the refrigerant. In the evaporator 11, the air that has exchanged heat with the refrigerant is cooled. The evaporator 11 is, for example, a fin-and-tube type heat exchanger having a heat transfer tube and a plurality of heat dissipation fins. In FIG. 3, the fins are omitted from the drawing. The evaporator blower 12 sends the air cooled in the evaporator 11 to the accommodation chamber 55, and also sucks in air from the accommodation chamber 55 and supplies the sucked air to the evaporator 11. This promotes heat exchange between the air and the refrigerant in the evaporator 11.

[0028] The refrigerant charged in the refrigerant circuit 30 will be described. From the viewpoint of protecting the global environment, it is desirable that the refrigerant charged in the refrigerant circuit 30 is a refrigerant with a small global warming potential (GWP). In the first embodiment, the refrigerant charged in the refrigerant circuit 30 is a flammable refrigerant. The flammable refrigerant has a larger average molecular weight than air. That is, the flammable refrigerant has a larger density than air and is heavier than air under atmospheric pressure. Therefore, the flammable refrigerant has the property of moving in the direction of gravity in the air.

[0029] Known flammable refrigerants include, for example, tetrafluoropropene (CFCF=CH: HFO-1234yf), difluoromethane (CHF: R32), propane (R290), propylene (R1270), ethane (R170), butane (R600), and isobutane (R600a). In the first embodiment, one of these refrigerants or a mixed refrigerant consisting of two or more refrigerants is used.

[0030] The refrigerant leakage detection sensor 20 is a sensor that detects the refrigerant diffused in the air. For example, a catalytic combustion type, a semiconductor type, a heat conduction type, a low potential electrolysis type, an infrared type, or other type of sensor can be used as the refrigerant leakage detection sensor 20. An oxygen sensor may also be used as the refrigerant leakage detection sensor 20. A method for detecting the refrigerant concentration when an oxygen sensor is used as the refrigerant leakage detection sensor 20 will be described. The normal oxygen concentration is obtained in advance based on the output of the oxygen sensor. When the refrigerant leaks from the refrigerant circuit 30, the oxygen concentration in the air decreases. The refrigerant concentration can be indirectly detected by calculating the inflow gas concentration as the refrigerant gas that has flowed into the air due to the decrease in oxygen concentration. For example, a galvanic cell type, a polaroid type, a zirconia type, or other type of sensor can be used as the oxygen sensor. The refrigerant leakage detection sensor 20 transmits a detection signal corresponding to the detected refrigerant concentration Cr to the control device 40.

[0031] Next, the location of the refrigerant leakage detection sensor 20 in the refrigerating / freezing unit 1 will be described with reference to FIGS.

[0032] As shown in FIG. 3 and FIG. 4, an opening 56 is formed in the unit base 2 and the ceiling plate 51. As shown in FIG. 4, a partition plate 18 is provided below the opening 56 to divide the opening 56 into an inlet 57 and an outlet 58. The inlet 57 draws air from the accommodation chamber 55 into the cooling chamber 23. The outlet 58 blows cold air from the cooling chamber 23 into the accommodation chamber 55. A duct 17 is provided below the ceiling plate 51, which communicates with the cooling chamber 23 through the outlet 58. The cooling chamber 23 may be connected to the opening 56 through a heat insulating material not shown. The duct 17 serves to guide the cold air flowing out from the outlet 58 so that it is blown out along the ceiling plate 51 into the accommodation chamber 55. The duct 17 is fixed to the unit base 2 or the ceiling plate 51. As shown in FIG. 4, a refrigerant leakage detection sensor 20 is provided in the duct 17.

[0033] In the configuration example shown in FIG. 4, the refrigerant leakage detection sensor 20 is disposed on the bottom plate 17c. It is possible to install the refrigerant leakage detection sensor 20 below the evaporator 11. However, since the evaporator 11 is stored in a relatively narrow space inside the heat-insulating box 13, it cannot be said that there is enough space to install the refrigerant leakage detection sensor 20. For example, if the refrigerant leakage detection sensor 20 is a semiconductor sensor, the size of the sensor is approximately "width 25 mm × depth 25 mm × height 20 mm". In this case, the sensor storage box that stores the sensor is approximately "width 50 mm × depth 50 mm × height 30 mm". Considering the fixing of the sensor storage box, it is difficult to install the sensor storage box below the evaporator 11.

[0034] In contrast, in the first embodiment, as shown in FIG. 4, when the refrigerant leakage detection sensor 20 is provided in the duct 17, the sensor storage box (not shown) can be arranged in a wide range of positions, and the sensor storage box can be easily fixed to the duct 17. When the evaporator blower 12 operates, air is sucked from the accommodation chamber 55 through the suction port 57 into the cooling chamber 23, and the cool air is blown out from the cooling chamber 23 through the blower port 58 into the duct 17. The cool air blown out into the duct 17 passes through the duct 17 and is blown out into the accommodation chamber 55. The refrigerant leaking from the evaporator 11 rides on the airflow generated by the evaporator blower 12, flows into the duct 17, which has a space narrower than the cooling chamber 23, and is guided to the refrigerant leakage detection sensor 20. As a result, the refrigerant leakage is detected early by the refrigerant leakage detection sensor 20.

[0035] In addition, in the present embodiment 1, since the refrigerant is a flammable refrigerant that is heavier than air, when the refrigerant leaks from the evaporator 11, it flows by its own weight into the duct 17 installed below the cooling chamber 23, and is naturally guided to the refrigerant leakage detection sensor 20. As a result, the refrigerant leakage is detected by the refrigerant leakage detection sensor 20 more quickly and reliably.

[0036] Next, the configurations of the duct 17 and the partition plate 18 shown in Fig. 4 will be described. Fig. 5 is an external perspective view showing an example of the configuration of the duct shown in Fig. 4. Fig. 6 is an external perspective view showing an example of the configuration of the partition plate shown in Fig. 4. In Fig. 5, the refrigerant leakage detection sensor 20 is omitted from the drawing.

[0037] As shown in Fig. 5, the duct 17 has a bottom plate 17c, two side plates 17d, and a back plate 17e. The bottom plate 17c has a rectangular planar shape. The two side plates 17d and the back plate 17e each have a rectangular shape. A rectangular flange portion 17f extending horizontally is connected to the upper end of each of the two side plates 17d. The back plate 17e is parallel to the partition plate 18 shown in Fig. 4.

[0038] As shown in Fig. 5, two circular fixing holes 17a are formed in each flange portion 17f. The number of fixing holes 17a formed in the flange portion 17f may be one or may be three or more. The duct 17 is fixed to the ceiling plate 51 or the unit base 2 by fastening members (not shown) such as screws through the four fixing holes 17a. Two circular first fastening holes 17b are formed in the back plate 17e. The number of first fastening holes 17b formed in the back plate 17e may be one or may be three or more.

[0039] As shown in Fig. 4, the refrigerant leakage detection sensor 20 is disposed on the bottom plate 17c at a position closer to the partition plate 18 than the center in the X-axis direction. Although not shown in Fig. 5, the refrigerant leakage detection sensor 20 shown in Fig. 4 is desirably disposed on the bottom plate 17c at the center in the Y-axis direction, but may be disposed at a position closer to either of the two side plates 17d. The refrigerant leakage detection sensor 20 may also be disposed at a position in contact with the back plate 17e in the X-axis direction.

[0040] In order to make the configuration easier to understand, FIG. 6 shows the partition plate 18, the heat insulating material 19, and the drain pan 16 in a state separated from each other. As shown in FIG. 6, the partition plate 18 is formed with two second fastening holes 18b that are longer in the vertical direction (Z axis) than in the horizontal direction (Y axis). The number of second fastening holes 18b formed in the partition plate 18 may be one or may be three or more. A fastening member (not shown) is attached to each of the first fastening holes 17b of the duct 17 shown in FIG. 5 and each of the second fastening holes 18b of the partition plate 18 shown in FIG. 6, thereby connecting the back plate 17e of the duct 17 to the partition plate 18. The fastening member is, for example, a bolt and a nut. This configuration prevents the refrigerant from leaking into the storage chamber 55 from the gap between the back plate 17e of the duct 17 and the partition plate 18. In addition, the duct 17 is supported in a more stable state via the partition plate 18.

[0041] As shown in FIG. 6, the partition plate 18 has a flange portion 18a formed at the upper end. The partition plate 18 is fixed to the ceiling plate 51 or the unit base 2 shown in FIG. 4 by fastening members such as screws in fixing holes (not shown) formed in the flange portion 18a. The partition plate 18 is connected to the duct 17 shown in FIG. 5 with a heat insulating material 19 sandwiched between the partition plate 18 and the drain pan 16. The partition plate 18 may be connected to the duct 17 shown in FIG. 5 with the upper end in contact with the lower surface of the drain pan 16 without the heat insulating material 19. With this configuration, even if the refrigerant leaking from the evaporator 11 flows into the drain pan 16, the refrigerant leaking from the drain pan 16 can be guided along the partition plate 18 into the duct 17 shown in FIG. 5.

[0042] Here, the reason why the second fastening hole 18b is longer in the vertical direction than in the horizontal direction will be described. For example, when the refrigerator-freezer 50 is used for refrigeration, the thickness L1 of the ceiling board 51 shown in FIG. 4 varies within a range of 40 mm to 75 mm depending on the specifications. When attaching the duct 17, the worker slides the duct 17 in the vertical direction to a position where the dimension L2 from the lower surface of the ceiling board 51 to the bottom board 17c of the duct 17 becomes constant. Then, the worker connects the duct 17 and the partition board 18 with a fastening member (not shown) at the position where the dimension L2 becomes constant. In this way, the dimension L2 can be made constant regardless of the thickness L1 of the ceiling board 51.

[0043] When there is one first fastening hole 17b formed in the back plate 17e of the duct 17, there is only to be one second fastening hole 18b formed in the partition plate 18. The back plate of the duct 17 is connected to the partition plate 18 by a fastening member (not shown) attached to the one first fastening hole 17b of the duct 17 and the one second fastening hole of the partition plate 18.

[0044] Next, the control performed by the control device 40 for the refrigeration and freezing unit 1 will be described. FIG. 7 is a block diagram for explaining the control performed by the control device in the refrigeration and freezing unit according to the first embodiment. The control device 40 is, for example, a microcomputer. The control device 40 performs signal processing related to the control of the refrigeration and freezing unit 1 to operate the refrigeration and freezing unit 1 in one of the operation modes of the cooling operation, the defrosting operation, and the refrigerant recovery operation. The control device 40 controls the compressor 3, the condenser blower 5, the expansion valve 10, the evaporator blower 12, the hot gas solenoid valve 8, and the liquid solenoid valve 9 in accordance with the operation mode. The cooling operation is a normal operation for cooling the object to be cooled that is accommodated in the accommodation chamber 55. The defrosting operation is an operation mode for removing frost that has adhered to the evaporator 11. The refrigerant recovery operation is an operation mode for recovering the refrigerant in the refrigerant circuit 30 to the compressor 3 and the condenser 4. Details of each operation mode will be described later.

[0045] When the operating mode is cooling operation, the control device 40 controls the operating frequency of the compressor 3 and the rotation speeds of the condenser blower 5 and the evaporator blower 12, and adjusts the opening of the expansion valve 10, so that the room temperature Tr detected by the temperature sensor 24 matches the set temperature Tset.

[0046] When the refrigeration / freezing unit 1 continues the cooling operation, the evaporator 11 frosts and the heat exchange capacity decreases. Therefore, when the refrigeration / freezing unit 1 operates the cooling operation for a predetermined time, the control device 40 causes the refrigeration / freezing unit 1 to execute a defrosting operation. Specifically, the control device 40 switches the hot gas solenoid valve 8 from a closed state to an open state. As a result, the high-temperature refrigerant discharged from the compressor 3 flows through the bypass circuit 25 to the evaporator 11, and is defrosted. Drain water, which is the water from which the frost has melted, is discharged from the refrigeration / freezing unit 1 to the outside through the drain pan 16.

[0047] In the present embodiment 1, since the refrigerant is a flammable refrigerant, when the operation mode is the defrost operation, the control device 40 operates the condenser blower 5 to ensure the amount of air required to agitate the leaking refrigerant in preparation for refrigerant leakage. Therefore, when the refrigerant discharged from the compressor 3 flows through the condenser 4 and is cooled by being decompressed by the expansion valve 10, the cooled refrigerant mixes with the high-temperature refrigerant that has flowed through the hot gas solenoid valve 8, and the temperature of the hot gas drops. In order to prevent a drop in the temperature of the hot gas supplied to the evaporator 11, the control device 40 switches the liquid solenoid valve 9 or the expansion valve 10 to a closed state when performing the defrost operation. By switching the expansion valve 10 or the liquid solenoid valve 9 to a closed state, the flow of the cooled refrigerant to the evaporator 11 can be prevented. Instead of the hot gas solenoid valve 8, a three-way valve (not shown) may be provided.

[0048] Furthermore, the control device 40 uses the detection signal received from the refrigerant leakage detection sensor 20 to determine whether or not refrigerant leakage from the evaporator 11 has occurred. Specifically, when the control device 40 receives a detection signal from the refrigerant leakage detection sensor 20, it compares the refrigerant concentration Cr indicated by the received detection signal with a predetermined threshold value Cth. The threshold value Cth is stored in the memory 42. The control device 40 determines whether or not the refrigerant concentration Cr is equal to or greater than the threshold value Cth. If the refrigerant concentration Cr is equal to or greater than the threshold value Cth, the control device 40 determines that refrigerant has leaked from the evaporator 11.

[0049] When the control device 40 determines that the refrigerant has leaked from the evaporator 11, it causes the refrigeration / freezing unit 1 to execute a refrigerant recovery operation. In the refrigerant recovery operation, the control device 40 switches the expansion valve 10 or the liquid solenoid valve 9 to a closed state in order to prevent the flow of the refrigerant from the condenser 4 to the evaporator 11. The control device 40 also operates the compressor 3. As a result, the refrigerant on the evaporator 11 side is sucked out to the compressor 3. The high-temperature gas refrigerant discharged from the compressor 3 exchanges heat with the air when flowing through the condenser 4. The gas refrigerant is liquefied by this heat exchange. When the liquid refrigerant flows out of the condenser 4, it reaches the expansion valve 10 or the liquid solenoid valve 9. Since the expansion valve 10 or the liquid solenoid valve 9 is in a closed state, the liquid refrigerant is recovered in the refrigerant piping 31 between the compressor 3 and the condenser 4, the refrigerant piping 31 between the condenser 4 and the expansion valve 10 or the liquid solenoid valve 9, and the condenser 4.

[0050] The control device 40 has a timer (not shown) that measures time, and monitors the elapsed time t from the start of the refrigerant recovery operation. When the elapsed time t reaches a predetermined reference time tref, the control device 40 stops the compressor 3 and ends the refrigerant recovery operation. The reference time tref is determined by taking into consideration the charge amount of refrigerant sealed in the refrigerant circuit 30, the capacity of the compressor 3, and the specifications of the refrigeration and freezing unit 1, and the time required to move the refrigerant toward the compressor 3 and the condenser 4. The reference time tref is stored in the memory 42.

[0051] In this way, the refrigeration and freezing unit 1 of this embodiment 1 not only has a refrigerant leakage detection function, but also performs refrigerant recovery operation equivalent to the function of an internal refrigerant leakage cut-off device, and therefore meets the safety mechanism requirements described in the standard "JRA 4078:2021."

[0052] Furthermore, when the control device 40 receives a stop instruction signal from the high pressure switch 21, it stops the compressor 3. The hardware configuration of the control device 40 has a processor 41 such as a CPU (Central Processing Unit) and a memory 42 that stores a program, as shown in Fig. 7, for example. The memory 42 is a non-volatile semiconductor memory such as a flash memory. The functions of the control device 40 are performed by the processor 41 executing the program. The hardware configuration shown in Fig. 7 is one example. The control device 40 may be formed of a dedicated circuit such as an ASIC (Application Specific Integrated Circuit).

[0053] Next, a description will be given of the operation of the refrigerating and freezing unit 1 according to the present embodiment 1. Fig. 8 is a flow diagram showing an example of an operation procedure of the refrigerating and freezing unit according to the present embodiment 1.

[0054] In step S1, the control device 40 causes the refrigeration / refrigeration unit 1 to perform a cooling operation. Specifically, the control device 40 controls the operating frequency of the compressor 3 and the rotation speeds of the evaporator blower 12 and the condenser blower 5, and adjusts the opening of the expansion valve 10, so that the room temperature Tr detected by the temperature sensor 24 matches the set temperature Tset. In step S2, the control device 40 determines whether the refrigerant concentration Cr detected by the refrigerant leakage detection sensor 20 is equal to or greater than the threshold value Cth. If the refrigerant concentration Cr is less than the threshold value Cth (step S2: No), the control device 40 returns to the process of step S1 and continues to control the cooling operation.

[0055] On the other hand, if the result of the determination in step S2 is that the refrigerant concentration Cr is equal to or greater than the threshold value Cth (step S2: Yes), the control device 40 determines that a refrigerant leak has occurred in the evaporator 11, issues an alarm, and starts a refrigerant recovery operation (step S3). Specifically, the control device 40 switches the expansion valve 10 or the liquid solenoid valve 9 to a closed state and continues the operation of the compressor 3. If the compressor 3 is stopped in step S3, the control device 40 operates the compressor 3. In addition, the control device 40 monitors the elapsed time t from the start of the refrigerant recovery operation.

[0056] In step S4, the control device 40 determines whether the elapsed time t from the start of the refrigerant recovery operation is equal to or greater than the reference time tref. If the elapsed time t is less than the reference time tref (step S4: No), the control device 40 returns to the process of step S3. If the determination in step S4 shows that the elapsed time t has reached the reference time tref (step S4: Yes), the control device 40 stops the compressor 3 and ends the refrigerant recovery operation (step S5).

[0057] In this way, when refrigerant leakage occurs from the evaporator 11, the refrigerant leakage detection sensor 20 detects the refrigerant leakage at an early stage. When the refrigerant leakage detection sensor 20 detects a refrigerant leakage, the control device 40 stops the cooling operation of the freezing and refrigerating unit 1 and performs a refrigerant recovery operation. Therefore, when refrigerant leakage occurs from the evaporator 11, the amount of refrigerant inside the evaporator 11 can be reduced more quickly, and the amount of refrigerant leakage can be reduced.

[0058] The refrigeration / refrigeration unit 1 of the present embodiment 1 includes a cooling chamber 23 that communicates with the storage chamber 55 through an opening 56 formed in the ceiling plate 51 of the storage chamber 55, an evaporator 11 provided in the cooling chamber 23, an evaporator blower 12, a partition plate 18, and a duct 17. The evaporator blower 12 draws air from the storage chamber 55 and sends the drawn air to the evaporator 11. The partition plate 18 divides the opening 56 into an inlet 57 and an outlet 58. The duct 17 communicates with the cooling chamber 23 through the outlet 58, and guides the cold air flowing out from the outlet 58 to be blown out along the ceiling plate 51 into the storage chamber 55. A refrigerant leakage detection sensor 20 that detects the refrigerant contained in the cold air is provided in the duct 17.

[0059] According to the first embodiment, when refrigerant leaks from the evaporator 11, the refrigerant leaking from the evaporator 11 rides on the airflow generated by the evaporator blower 12 from the evaporator 11 and flows into the duct 17. Since the refrigerant leakage detection sensor 20 is disposed in the duct 17, even if the refrigerant leaking from the evaporator 11 is due to a microleak phenomenon, the refrigerant leakage is detected early by the refrigerant leakage detection sensor 20. Therefore, by performing the refrigerant recovery operation early, the concentration of the leaking refrigerant can be suppressed to the lower flammable limit.

[0060] For example, when the refrigerant is a flammable refrigerant such as R290, the refrigerant is heavier than air, and therefore the refrigerant flows from the evaporator 11 into the duct 17 disposed below the evaporator 11 due to its own weight, even when the evaporator blower 12 is stopped. Since the refrigerant leakage detection sensor 20 is disposed in the duct 17, refrigerant leakage can be detected more quickly and reliably. Therefore, by performing the refrigerant recovery operation early, the concentration of the leaking refrigerant can be suppressed to or below the lower flammability limit of R290.

[0061] Various aspects of the freezer-refrigerator unit and the freezer-refrigerator of the present disclosure are summarized below as appendices.

[0062] (Appendix 1) A refrigeration and freezing unit disposed above a chamber in which an object to be cooled is accommodated, a cooling chamber communicating with the storage chamber through an opening formed in a ceiling panel of the storage chamber; an evaporator provided in the cooling chamber; an evaporator blower that draws in air from the storage chamber and sends the air to the evaporator; a partition plate that divides the opening into an intake port through which the air is drawn from the storage chamber to the cooling chamber and an outlet port through which cool air is blown out from the cooling chamber to the storage chamber; a duct that communicates with the cooling chamber through the air outlet and guides the cool air flowing out from the air outlet so that the cool air is blown out along the ceiling board into the storage chamber; a refrigerant leakage detection sensor provided in the duct for detecting a refrigerant contained in the cold air; A refrigeration and freezing unit having (Appendix 2) A drain pan is provided below the evaporator, The partition plate is connected to the duct with an upper end thereof in contact with a lower surface of the drain pan. 10. A refrigeration and storage unit as described in Appendix 1. (Appendix 3) The duct has a plate having one or more first fastening holes formed therein and parallel to the partition plate; The partition plate is formed with one or more second fastening holes each having a shape longer in the vertical direction than in the horizontal direction, The plate of the duct is connected to the partition plate by a fastening member attached to the one first fastening hole of the duct and the one second fastening hole of the partition plate, or the plurality of first fastening holes of the duct and the plurality of second fastening holes of the partition plate; 10. A refrigeration / freezing unit as claimed in claim 1 or 2. (Appendix 4) a refrigerant circuit in which a compressor, a condenser, an expansion valve, and the evaporator are connected via a refrigerant pipe; A check valve provided at a refrigerant suction port of the compressor. 4. A refrigeration and freezing unit according to any one of claims 1 to 3. (Appendix 5) a liquid solenoid valve provided in the refrigerant piping between the expansion valve and the evaporator; and a control device that performs a refrigerant recovery operation by switching the expansion valve or the liquid solenoid valve to a closed state and operating the compressor when the refrigerant concentration detected by the refrigerant leakage detection sensor is equal to or higher than a predetermined threshold value. Refrigeration and storage units as described in Appendix 4. (Appendix 6) a condenser blower for supplying air to the condenser, The control device operates the condenser blower when performing a defrosting operation to remove frost adhering to the evaporator. 10. A refrigeration and freezing unit as described in appended claim 5. (Appendix 7) The refrigerant is a flammable refrigerant. 7. A refrigeration and freezing unit according to any one of claims 1 to 6. (Appendix 8) A refrigeration and freezing unit according to any one of claims 1 to 7; A chamber in which an object to be cooled is accommodated; A refrigerator-freezer having the same. [Explanation of symbols]

[0063] 1 refrigeration and cooling unit, 2 unit base, 3 compressor, 4 condenser, 5 condenser blower, 6 reactor box, 7 control box, 8 hot gas solenoid valve, 9 liquid solenoid valve, 10 expansion valve, 11 evaporator, 12 evaporator blower, 13 insulation box, 14, 15 support plate, 16 drain pan, 17 duct, 17a fixing hole, 17b first fastening hole, 17c bottom plate, 17d side plate, 17e back plate, 17f flange portion, 18 partition plate, 18a flange portion, 18b second fastening hole, 19 insulation material, 20 refrigerant leakage detection sensor, 21 high pressure pressure switch, 22 check valve, 23 cooling chamber, 24 temperature sensor, 25 bypass circuit, 30 refrigerant circuit, 31 refrigerant piping, 40 control device, 41 processor, 42 Memory, 50 refrigerator / freezer, 51 ceiling panel, 52 side wall panel, 53 floor panel, 54 door, 55 storage room, 56 opening, 57 intake port, 58 exhaust port.

Claims

1. A refrigeration and freezing unit disposed above a chamber in which an object to be cooled is accommodated, a cooling chamber communicating with the storage chamber through an opening formed in a ceiling panel of the storage chamber; an evaporator provided in the cooling chamber; an evaporator blower that draws in air from the storage chamber and sends the air to the evaporator; a partition plate that divides the opening into an intake port through which the air is drawn from the storage chamber to the cooling chamber and an outlet port through which cool air is blown out from the cooling chamber to the storage chamber; a duct that communicates with the cooling chamber through the air outlet and guides the cool air flowing out from the air outlet so that the cool air is blown out along the ceiling board into the storage chamber; a refrigerant leakage detection sensor provided in the duct for detecting a refrigerant contained in the cold air; A refrigeration and freezing unit having

2. A drain pan is provided below the evaporator, The partition plate is connected to the duct with an upper end thereof in contact with a lower surface of the drain pan.

2. The refrigeration unit according to claim 1.

3. The duct has a plate having one or more first fastening holes formed therein and parallel to the partition plate; The partition plate is formed with one or more second fastening holes each having a shape longer in the vertical direction than in the horizontal direction, The plate of the duct is connected to the partition plate by a fastening member attached to the one first fastening hole of the duct and the one second fastening hole of the partition plate, or the plurality of first fastening holes of the duct and the plurality of second fastening holes of the partition plate; 2. The refrigeration unit according to claim 1.

4. a refrigerant circuit in which a compressor, a condenser, an expansion valve, and the evaporator are connected via a refrigerant pipe; A check valve provided at a refrigerant suction port of the compressor.

2. The refrigeration unit according to claim 1.

5. a liquid solenoid valve provided in the refrigerant piping between the expansion valve and the evaporator; and a control device that performs a refrigerant recovery operation by switching the expansion valve or the liquid solenoid valve to a closed state and operating the compressor when the refrigerant concentration detected by the refrigerant leakage detection sensor is equal to or higher than a predetermined threshold value.

5. The refrigeration unit according to claim 4.

6. a condenser blower for supplying air to the condenser, The control device operates the condenser blower when performing a defrosting operation to remove frost adhering to the evaporator.

6. The refrigeration unit according to claim 5.

7. The refrigerant is a flammable refrigerant.

2. The refrigeration unit according to claim 1.

8. A refrigeration and freezing unit according to any one of claims 1 to 7; A chamber in which an object to be cooled is accommodated; A refrigerator-freezer having the same.

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