JP7518418B2 - Air conditioning unit - Google Patents

Description

Regarding air conditioning units.

Patent Document 1 (Patent No. 5430604) discloses a cascade refrigeration system equipped with a low-stage refrigeration cycle using carbon dioxide refrigerant and a high-stage refrigeration cycle that assists the heat dissipation of the low-stage refrigeration cycle. In the cascade refrigeration system of Patent Document 1, the high-stage evaporator and the low-stage condenser exchange heat in a cascade condenser, and the auxiliary radiator installed in the front stage of the low-stage refrigeration cycle of the cascade condenser and the high-stage condenser are integrated to form an integrated radiator.

However, the above-mentioned Patent Document 1 discloses that HC refrigerants, HFC refrigerants, HFO refrigerants, etc. are used in the high-temperature refrigeration cycle. If a flammable refrigerant leaks from the high-temperature condenser, there is a possibility that the electrical equipment unit may become an ignition source and cause a fire.

The air conditioning unit of the first aspect includes an electrical equipment unit, a first heat exchanger, a second heat exchanger, a fan, a casing, and a partition plate. The first heat exchanger exchanges heat between a combustible first refrigerant and air. The second heat exchanger exchanges heat between a non-combustible second refrigerant and air. The fan flows air through the first heat exchanger and the second heat exchanger. The casing houses the electrical equipment unit, the first heat exchanger, the second heat exchanger, and the fan. The partition plate divides the inside of the casing into a first chamber in which the first heat exchanger, the second heat exchanger, and the fan are arranged, and a second chamber in which the electrical equipment unit is arranged. The partition plate has a communication hole that communicates between the first chamber and the second chamber, above the first brazed portion that is located at the top of the multiple brazed portions of the first heat exchanger.

In the air conditioning unit of the first aspect, the communication hole provided in the partition plate and the fan disposed in the first chamber allow air to flow from the second chamber in which the electrical equipment unit is disposed to the first chamber in which the first heat exchanger through which the first refrigerant flows is disposed. Furthermore, since the communication hole is provided at a position higher than the first brazed portion, which is located at the highest position of the first heat exchanger through which the flammable first refrigerant flows, even if the first refrigerant leaks in the first chamber, the first refrigerant can be prevented from flowing above the communication hole. This reduces the possibility of a fire caused by the electrical equipment unit in the second chamber as an ignition source.

The air conditioning unit of the second aspect is the air conditioning unit of the first aspect, and the communication hole is a hole for directing air around the electrical equipment unit to the fan.

In the air conditioning unit of the second aspect, the air around the electrical equipment unit, which is a potential ignition source, is guided into the first chamber, so that even if the first refrigerant leaks, the first refrigerant can be prevented from flowing around the electrical equipment unit.

The air conditioning unit of the third aspect is the air conditioning unit of the first or second aspect, further comprising a bell mouth. The bell mouth is disposed in the first chamber and has a cylindrical portion surrounding the fan. The lower end of the electrical equipment unit is located above the lower end of the cylindrical portion.

In the air conditioning unit of the third aspect, a fan is placed inside the cylindrical portion of the bellmouth. Normally, the first refrigerant is heavier than air, so even if the first refrigerant leaks, the first refrigerant will remain below the lower end of the cylindrical portion. Here, the lower end of the board on which the electrical equipment unit is mounted is located above the lower end of the cylindrical portion, so the first refrigerant can be further prevented from flowing into the electrical equipment unit.

The air conditioning unit of the fourth aspect is an air conditioning unit of any one of the first to third aspects, in which the lower end of the electrical equipment unit is located above the first brazed portion.

In the air conditioning unit of the fourth aspect, even if the first refrigerant leaks, the first refrigerant remains below the first brazed portion. Here, the lower end of the board on which the electrical equipment unit is mounted is located above the first brazed portion, so that the first refrigerant can be further prevented from flowing into the electrical equipment unit.

The air conditioning unit of the fifth aspect is an air conditioning unit of any one of the first aspect to the fourth aspect, in which the first heat exchanger is positioned lower than the second heat exchanger.

In the air conditioning unit of the fifth aspect, the first heat exchanger through which the flammable refrigerant flows is positioned below the second heat exchanger through which the non-flammable refrigerant flows. Therefore, even if the first refrigerant leaks, the first refrigerant tends to accumulate below, making it easy to realize an air conditioning unit that prevents the first refrigerant from flowing into the electrical equipment unit.

The air conditioning unit of a sixth aspect is the air conditioning unit of any one of the first aspect to the fifth aspect, further comprising a first compressor, a second compressor, and a bell mouth. The first compressor is disposed in the second chamber and compresses a first refrigerant. The second compressor is disposed in the second chamber and compresses a second refrigerant. The bell mouth is disposed in the first chamber and has a cylindrical portion surrounding the fan. The terminal of the first compressor and the terminal of the second compressor are located above the lower end of the cylindrical portion.

In the air conditioning unit of the sixth aspect, even if the first refrigerant leaks, the first refrigerant remains below the lower end of the cylindrical portion of the bellmouth. Here, the terminal is located above the lower end of the cylindrical portion, which reduces the possibility of ignition caused by the terminal of the second chamber as an ignition source.

1 is a schematic configuration diagram of a dual cascade refrigeration cycle device including an outdoor unit according to an embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view of the outdoor unit. FIG. 2 is a schematic plan view of the outdoor unit. FIG. 4 is a diagram showing the operation of the cascade refrigeration cycle device in cooling operation. FIG. 4 is a diagram showing the operation of the cascade refrigeration cycle device in heating operation. FIG. 4 is a diagram showing a plurality of brazed portions.

(1) Configuration of the cascade refrigeration cycle device As shown in FIG. 1 , a cascade refrigeration cycle device 1 employing an outdoor unit 2 according to an embodiment of the present disclosure is a device used for cooling and heating the interior of a building or the like by performing a vapor compression refrigeration cycle operation.

The cascade refrigeration cycle device 1 has a first cycle 10 and a second cycle 20. The cascade refrigeration cycle device 1 of this embodiment has a binary refrigerant circuit consisting of a vapor compression type first cycle 10 and a vapor compression type second cycle 20, and performs a binary refrigeration cycle.

In the first cycle 10, a combustible first refrigerant circulates. The first refrigerant has a critical point of, for example, 40°C or higher. The first refrigerant is, for example, a hydrocarbon refrigerant such as R1234yf, R1234ze, or R32, and in this embodiment, is R290. The specific gravity of the first refrigerant is greater than that of air.

The second cycle 20 circulates a non-flammable second refrigerant. The second refrigerant has a critical point of, for example, less than 40°C. The second refrigerant includes, for example, carbon dioxide, and in this embodiment, carbon dioxide is the only refrigerant.

The first cycle 10 and the second cycle 20 are thermally connected via a cascade heat exchanger 30.

The cascade refrigeration cycle system 1 includes an outdoor unit 2 and an indoor unit 3. The outdoor unit 2 and the indoor unit 3 are connected to each other via interconnecting pipes 4 and 5.

(1-1) First Cycle The first cycle 10 constitutes a subcooling circuit during cooling operation. The first cycle 10 includes a first compressor 11, a first heat exchanger 12, a first expansion mechanism 13, and a cascade heat exchanger 30.

The first compressor 11 is a device for compressing the first refrigerant, and is, for example, a volumetric compressor such as a scroll type whose operating capacity can be varied by inverter controlling the compressor motor.

As shown in FIG. 2, the first compressor 11 has a first terminal 111. A power supply wiring is connected to the first terminal 111. Here, the first terminal 111 is a harness connection portion.

The first heat exchanger 12 is a device for exchanging heat between the first refrigerant and the outdoor air. In the first heat exchanger 12, the first refrigerant obtains cold or hot heat from the outdoor air. The first heat exchanger 12 is, for example, a fin-and-tube type heat exchanger composed of a large number of heat transfer tubes and fins.

The first expansion mechanism 13 is a device that reduces the pressure of the first refrigerant, for example, an electric expansion valve.

The cascade heat exchanger 30 is a device for performing heat exchange between a first refrigerant and a second refrigerant without mixing them. The cascade heat exchanger 30 is, for example, a plate-type heat exchanger. The cascade heat exchanger 30 has a first flow path 31 belonging to the first cycle 10 and a second flow path 32 belonging to the second cycle 20. The gas side of the first flow path 31 is connected to the first compressor 11, and the liquid side is connected to the first expansion mechanism 13.

When the first heat exchanger 12 is used as a condenser and the second heat exchanger 23 of the second cycle 20 described later is used as a radiator, the cascade heat exchanger 30 is intended to supercool the second refrigerant cooled by the second heat exchanger 23, and serves as an assistant to the second cycle 20.

(1-2) Second Cycle The second cycle 20 includes a second compressor 21, a switching mechanism 22, a second heat exchanger 23, a cascade heat exchanger 30, a second expansion mechanism 24, and a third heat exchanger 25.

The second compressor 21 is a device for compressing the second refrigerant, and is, for example, a volumetric compressor such as a scroll type whose operating capacity can be varied by inverter controlling the compressor motor.

As shown in FIG. 2, the second compressor 21 has a second terminal 211. A power supply wiring is connected to the second terminal 211. Here, the second terminal 211 is a harness connection portion.

The switching mechanism 22 is a device that switches between a first state (see the solid line of the switching mechanism 22 in FIG. 1) in which the second heat exchanger 23 functions as a radiator of the second refrigerant and the third heat exchanger 25 functions as an evaporator of the second refrigerant, and a second state (see the dashed line of the switching mechanism 22 in FIG. 1) in which the second heat exchanger 23 functions as an evaporator of the second refrigerant and the third heat exchanger 25 functions as a radiator of the second refrigerant. The switching mechanism 22 is, for example, a four-way switching valve. In the first state, the switching mechanism 22 connects the discharge side of the second compressor 21 to the gas side of the second heat exchanger 23, and connects the suction side of the second compressor 21 to the gas side of the third heat exchanger 25. In addition, in the second state, the switching mechanism 22 connects the discharge side of the second compressor 21 to the gas side of the third heat exchanger 25, and also connects the suction side of the second compressor 21 to the gas side of the second heat exchanger 23.

The second heat exchanger 23 is a device for exchanging heat between the second refrigerant and the outdoor air. In the second heat exchanger 23, the second refrigerant obtains cold or hot heat from the outdoor air. The second heat exchanger 23 is, for example, a fin-and-tube type heat exchanger composed of a large number of heat transfer tubes and fins.

The second cycle 20 has a second flow path 32 of a cascade heat exchanger 30. The gas side of the second flow path 32 is connected to the second heat exchanger 23, and the liquid side is connected to the third heat exchanger 25.

The second expansion mechanism 24 is a device that reduces the pressure of the second refrigerant, for example, an electric expansion valve.

The third heat exchanger 25 is a device for exchanging heat between the second refrigerant and the indoor air, and is, for example, a fin-and-tube type heat exchanger composed of a large number of heat transfer tubes and fins.

(1-3) Outdoor Unit In the following description, expressions indicating directions such as "up,""down," and "front" are used as appropriate, but these indicate the directions when the outdoor unit 2 is installed outdoors and in normal use. In this embodiment, the up-down direction is the vertical direction.

The outdoor unit 2 is placed in a space different from the space in which the indoor unit 3 is placed. Here, the outdoor unit 2 is installed outdoors (on the roof of a building, near the exterior wall of a building, etc.).

The outdoor unit 2 has the above-mentioned first cycle 10, a part of the second cycle 20, a casing 41, an electrical equipment unit 420 including electrical equipment 42 and a board 43, a fan 44, a bell mouth 45, a partition plate 46, and a refrigerant leakage sensor 47. Specifically, the outdoor unit 2 has the first compressor 11, the first heat exchanger 12, the first expansion mechanism 13, the second compressor 21, the switching mechanism 22, the second heat exchanger 23, the second expansion mechanism 24, the cascade heat exchanger 30, and the casing 41, the electrical equipment 42, the board 43, the fan 44, the bell mouth 45, the partition plate 46, and the refrigerant leakage sensor 47 shown in FIG. 1.

The casing 41 houses the first compressor 11, the first heat exchanger 12, the first expansion mechanism 13, the second compressor 21, the switching mechanism 22, the second heat exchanger 23, the second expansion mechanism 24, the cascade heat exchanger 30, the casing 41, the electrical components 42, the circuit board 43, the fan 44, the bell mouth 45, the partition plate 46, and the refrigerant leakage sensor 47.

The casing 41 shown in FIG. 2 has a generally rectangular parallelepiped shape. Specifically, the casing 41 includes a front plate 411, a top plate 412, a bottom plate 413, and side plates 414.

The front plate 411 is a plate-like member that forms the front surface of the casing 41. An air outlet is formed in the front plate 411. The air outlet is an opening for blowing the outdoor air taken in from the outside of the casing 41 to the inside of the casing 41 out to the outside of the casing 41.

The top plate 412 is a plate-like member that forms the upper surface of the casing 41. The bottom plate 413 is a plate-like member that forms the lower surface of the casing 41. The top plate 412 and the bottom plate 413 face each other.

The side plate 414 is a plate-like member that forms the side surface of the casing 41. The lower portion of the side plate 414 is fixed to the bottom plate 413.

The casing 41 has an opening 415 for allowing outside air to flow to the communication hole 461 of the partition plate 46 described below. Here, the opening 415 is formed in the side plate 414 that partitions the second chamber S2 described below. Note that the opening 415 does not necessarily have to be formed in the side plate 414, and can be provided in any member that partitions the second chamber S2 from the outside of the casing 41.

The electrical equipment unit 420 has electrical equipment 42 (electrical components) mounted on a board 43.

The electrical equipment 42 controls the controlled objects such as the first compressor 11, the second compressor 21, the first expansion mechanism 13, the switching mechanism 22, and the second expansion mechanism 24. The electrical equipment 42 includes, for example, cooled elements such as power elements, reactors, capacitors, wiring connections, etc.

Electrical components 42 are attached to the board 43. The board 43 is, for example, a printed circuit board. The board 43 extends in the vertical direction. Here, multiple electrical components 42 are attached to the board 43.

The fan 44 causes air to flow through the first heat exchanger 12 and the second heat exchanger 23. In this embodiment, the fan 44 causes outdoor air to flow through both the first heat exchanger 12 and the second heat exchanger 23. Here, the fan 44 generates an air flow in which the outdoor air is guided to the first heat exchanger 12 and the second heat exchanger 23, where it is heat exchanged with the first refrigerant flowing through the first heat exchanger 12, and with the second refrigerant flowing through the second heat exchanger 23, and then discharged to the outside. The fan 44 is driven by a fan motor. Note that the fan that causes air to flow through the first heat exchanger 12 and the fan that causes air to flow through the second heat exchanger 23 may be provided separately.

The bellmouth 45 is disposed on the blowing side of the fan 44. The bellmouth 45 has a cylindrical portion that surrounds the fan 44. The cylindrical portion forms an opening. The fan 44 is disposed inside the cylindrical portion.

In FIG. 2, when viewed from the front, the fan 44 and the bellmouth 45 overlap the first heat exchanger 12 and the second heat exchanger 23. The bellmouth 45 faces an air outlet (not shown) formed in the front plate 411 of the casing 41.

The refrigerant leakage sensor 47 detects leakage of the first refrigerant. The refrigerant leakage sensor 47 is installed at the bottom inside the casing 41. The refrigerant leakage sensor 47 may also detect leakage of the second refrigerant.

The partition plate 46 is a plate-shaped member that extends in the vertical direction. The lower part of the partition plate 46 is fixed to the bottom plate 413 of the casing 41.

The partition plate 46 divides the inside of the casing 41 into a first chamber S1 and a second chamber S2. Each of the first chamber S1 and the second chamber S2 is a space defined by the front plate 411, the top plate 412, the bottom plate 413, and the side plates 414 of the casing 41 and the partition plate 46.

Here, the first chamber S1 is the air blowing chamber, and is an air guide passage through which air drawn in from the air inlet of the outdoor unit 2 flows to the air outlet. The second chamber S2 is the machine room.

In this embodiment, the first heat exchanger 12, the second heat exchanger 23, the fan 44, and the bell mouth 45 are arranged in the first chamber S1. The second chamber S2 is arranged with the first compressor 11, the second compressor 21, the switching mechanism 22, the first expansion mechanism 13, the second expansion mechanism 24, an electrical component unit 420 including electrical components 42 and a board 43, and a refrigerant leakage sensor 47.

The partition plate 46 has a communication hole 461. As shown in FIG. 5, the communication hole 461 is provided above the first brazed portion 121, which is the uppermost of the multiple brazed portions 120 of the first heat exchanger 12.

The brazed portion 120 is a portion in the first chamber S1 where the first refrigerant may leak from the first heat exchanger 12. In this embodiment, the brazed portion 120 is a joint between the heat transfer tubes constituting the first heat exchanger 12, a joint between the heat transfer tube and the fin, etc. The heat transfer tube includes a U-shaped tube, a branch tube, etc. In FIG. 5, the multiple brazed portions 120 are joints between a hairpin-shaped tube and a U-shaped tube or a branch tube. In addition, when the heat transfer tube and the fin are brazed, such as in a microchannel heat exchanger, the brazed portion also becomes a brazed portion.

In FIG. 2, the vertical height position of the communication hole 461 is indicated by P1, and the vertical height position of the first brazed portion 121 is indicated by P2. The vertical height position P1 of the communication hole 461 is the lowest end of the communication hole 461. Therefore, the height position P1 of the lowest end of the communication hole 461 is higher than the vertical height position of the first brazed portion 121.

The communication hole 461 is a hole for guiding the outside air that flows into the second chamber S2 from the opening 415 of the casing 41 to the first chamber S1. In this embodiment, the communication hole 461 is a hole for guiding the air around the electrical component unit 420 including the electrical components 42 and the board 43 to the fan 44. In other words, the communication hole 461 is a hole for guiding the outside air around the electrical component unit 420 including the electrical components 42 and the board 43 in the second chamber S2 to the fan 44 in the first chamber S1.

In FIG. 2, the communication hole 461 is located above the upper end of the first heat exchanger 12. In addition, the height position P1 of the communication hole 461 overlaps with the second heat exchanger 23.

In addition, the communication hole 461 is located above the lower end 451 of the cylindrical portion of the bell mouth 45. In addition, the communication hole 461 is located above the first terminal 111 of the first compressor 11 and the second terminal 211 of the second compressor 21.

Furthermore, the communication hole 461 is located above the lower end 431 of the electrical equipment unit 420 (here, the board 43). Here, the height position P1 of the lowest end of the communication hole 461 is located above the electrical equipment 42 that is located at the lowest position among the multiple electrical equipment 42.

Here, we will explain the layout of the various devices housed inside the casing 41 of the outdoor unit 2.

In the first chamber S1, the first heat exchanger 12 is located below the second heat exchanger 23. In other words, at least a portion of the first heat exchanger 12 is located below the second heat exchanger 23. The entire first heat exchanger 12 may be located below the second heat exchanger 23, or a portion of the first heat exchanger 12 may be located below the second heat exchanger 23.

The first heat exchanger 12 and the second heat exchanger 23 may be separate or integrated. The size of the first heat exchanger 12 may be approximately the same as the size of the second heat exchanger 23, and may be smaller in the vertical height direction.

In addition, in the second chamber S2, the electrical equipment unit 420 including the electrical equipment 42 and the circuit board 43 is disposed above the first compressor 11 and the second compressor 21.

In addition, within the casing 41, the lower end 431 of the electrical equipment unit 420 (here, the board 43) is located above the lower end 451 of the cylindrical portion of the bellmouth 45. In other words, the vertical height position of the lower end 431 of the electrical equipment unit 420 (here, the board 43 to which the electrical equipment 42 is attached) is higher than the opening lower end 451 of the bellmouth 45, which is located on the blowing side of the fan 44.

Here, the lowest electrical component 42 among the multiple electrical components 42 is located above the lower end 451 of the cylindrical portion of the bell mouth 45.

The lower end 431 of the electrical component unit 420 (here, the board 43) is located above the first brazing portion 121. In other words, the height position of the electrical component unit 420 (here, the board 43 to which the electrical components 42 are attached) is above the height position P1 of the first brazing portion 121.

Here, the electrical component 42 located at the lowest position among the multiple electrical components 42 is located above the first brazing portion 121.

In addition, the first terminal 111 of the first compressor 11 and the second terminal 211 of the second compressor 21 are located above the lower end 451 of the cylindrical portion of the bell mouth 45. Here, the lower end of the first terminal 111 of the first compressor 11 and the lower end of the second terminal 211 of the second compressor 21 are located above the lower end 451 of the cylindrical portion of the bell mouth 45.

(1-4) Indoor Unit The indoor unit 3 is installed indoors (inside the building). As described above, the indoor unit 3 is connected to the outdoor unit 2 via the connecting pipes 4 and 5, and constitutes a part of the second cycle 20.

As shown in FIG. 1, the indoor unit 3 has a third heat exchanger 25. Here, the indoor unit 3 is installed by embedding or hanging in the ceiling of a room of a building or the like, or by hanging on a wall surface of the room.

(1-5) Communication Pipes The communication pipes 4, 5 are refrigerant pipes that are installed on-site when the cascade refrigeration cycle apparatus 1 is installed in an installation location such as a building. One end of the liquid side communication pipe 4 is connected to the liquid side end of the outdoor unit 2, and the other end of the communication pipe 4 is connected to the liquid side end of the third heat exchanger 25 of the indoor unit 3. One end of the gas side communication pipe 5 is connected to the gas side end of the outdoor unit 2, and the other end of the communication pipe 5 is connected to the gas side end of the third heat exchanger 25 of the indoor unit 3.

(1-6) Control Unit The components of the outdoor unit 2 and the indoor unit 3 are controlled by the control unit 6. The control unit 6 is configured by communication connection between the electrical equipment 42, the board 43, etc. provided in the outdoor unit 2 and the control board, etc. (not shown) provided in the indoor unit 3. For convenience, the control unit 6 is illustrated in FIG. 1 at a position separate from the outdoor unit 2 and the indoor unit 3. The control unit 6 controls the components of the cascade refrigeration cycle apparatus 1 (here, the outdoor unit 2 and the indoor unit 3). In other words, the control unit 6 controls the operation of the entire cascade refrigeration cycle apparatus 1.

The control unit 6 is realized by a computer. The control unit 6 includes a control arithmetic unit and a storage device. The control arithmetic unit can be a processor such as a CPU or a GPU. The control arithmetic unit reads a program stored in the storage device, and performs predetermined image processing and arithmetic processing according to the program. Furthermore, the control arithmetic unit can write the results of calculations to the storage device and read information stored in the storage device according to the program.

(2) Operation of the cascade refrigeration cycle device The operation of the cascade refrigeration cycle device 1 will be described with reference to Figures 1 to 4. The cascade refrigeration cycle device 1 is capable of performing a cooling operation for cooling indoor air and a heating operation for heating indoor air for indoor air conditioning. In the cooling operation and the heating operation, the operation of the cascade refrigeration cycle device 1 is controlled by the control unit 6.

(2-1) Cooling Operation As shown in FIG. 3, during cooling operation, the switching mechanism 22 is switched to the first state (the state in which the switching mechanism 22 is in the solid line) so that the second heat exchanger 23 functions as a radiator for the second refrigerant and the third heat exchanger 25 functions as an evaporator for the second refrigerant.

In the second cycle 20, the second refrigerant discharged from the second compressor 21 is sent to the second heat exchanger 23 through the switching mechanism 22. The second refrigerant sent to the second heat exchanger 23 is cooled by heat exchange with the outdoor air supplied by the fan 44, and dissipates heat. The second refrigerant that has dissipated heat in the second heat exchanger 23 is sent to the second flow path 32 of the cascade heat exchanger 30. The second refrigerant sent to the second flow path 32 is further cooled in the cascade heat exchanger 30 by heat exchange with the first refrigerant flowing through the first flow path 31. The second refrigerant that has been further cooled in the cascade heat exchanger 30 is depressurized by the second expansion mechanism 24 and then flows out of the outdoor unit 2.

The second refrigerant that flows out of the outdoor unit 2 flows into the indoor unit 3 via the liquid side connecting pipe 4. In the indoor unit 3, the second refrigerant is sent to the third heat exchanger 25. The second refrigerant sent to the third heat exchanger 25 evaporates by being heated through heat exchange with the indoor air. The second refrigerant that has evaporated in the third heat exchanger 25 flows out of the indoor unit 3.

The second refrigerant that flows out of the indoor unit 3 flows into the outdoor unit 2 via the gas side connecting pipe 5. In the outdoor unit 2, the second refrigerant is sucked back into the second compressor 21 through the switching mechanism 22.

In the first cycle 10, the first refrigerant discharged from the first compressor 11 is sent to the first heat exchanger 12. The first refrigerant sent to the first heat exchanger 12 is cooled by heat exchange with the outdoor air supplied by the fan 44 and condenses. The first refrigerant condensed in the first heat exchanger 12 is depressurized by the first expansion mechanism 13 and then sent to the first flow path 31 of the cascade heat exchanger 30. The first refrigerant sent to the first flow path 31 is heated by heat exchange with the second refrigerant flowing in the second flow path 32 in the cascade heat exchanger 30 and evaporates. The first refrigerant evaporated in the cascade heat exchanger 30 is sucked back into the first compressor 11.

4, during heating operation, the switching mechanism 22 is switched to the second state (the state in which the switching mechanism 22 is in the broken line) so that the second heat exchanger 23 functions as an evaporator of the second refrigerant and the third heat exchanger 25 functions as a radiator of the second refrigerant. Also, during heating operation, the first compressor 11 is not started, and the first refrigerant is not circulated in the first cycle 10.

In the second cycle 20, the second refrigerant discharged from the second compressor 21 flows out of the outdoor unit 2 through the switching mechanism 22.

The refrigerant flowing out of the outdoor unit 2 flows into the indoor unit 3 via the gas side connecting pipe 5. In the indoor unit 3, the second refrigerant is sent to the third heat exchanger 25. The second refrigerant sent to the third heat exchanger 25 exchanges heat with the indoor air and is cooled, thereby releasing heat. The second refrigerant that has released heat in the third heat exchanger 25 flows out of the indoor unit 3.

The second refrigerant flowing out of the indoor unit 3 flows into the outdoor unit 2 via the liquid side connection pipe 4. In the outdoor unit 2, the second refrigerant is sent to the second heat exchanger 23 through the second expansion mechanism 24 and the second flow path 32 of the cascade heat exchanger 30. The second refrigerant sent to the second heat exchanger 23 is heated through heat exchange with the outdoor air supplied by the fan 44 and evaporates. The second refrigerant evaporated in the second heat exchanger 23 is sucked back into the second compressor 21 through the switching mechanism 22.

(3) Flow of the first refrigerant during refrigerant leakage As shown by arrow A in Fig. 2, in the outdoor unit 2, outside air flows from the opening 415 in the side plate 414 of the casing 41 to the second chamber S2, and further passes through the communication hole 461 in the partition plate 46 to flow into the first chamber S1. Here, the outside air that has passed through the communication hole 461 flows to the fan 44. When the fan 44 is driving, the outside air flows from the first chamber S1 to the outside of the casing 41.

The second refrigerant is non-flammable, so there is little risk of leakage, but the first refrigerant is flammable, so there is a risk of ignition if the first refrigerant flows into the electrical equipment unit 420 (particularly the electrical equipment 42), which is a source of ignition. The locations where the first refrigerant is most likely to leak are the multiple brazed parts of the first heat exchanger 12. In this embodiment, the communication hole 461 is located above the first brazed part 121, which is the uppermost of the multiple brazed parts 120, so that even if the first refrigerant, which is heavier than air, leaks, the first refrigerant is prevented from flowing above the communication hole 461.

Furthermore, while the fan 44 is operating, the outside air flowing from the communication hole 461 into the second chamber S2 prevents the leaked first refrigerant from flowing into the second chamber S2.

In addition, when the electrical equipment unit 420 (electrical equipment 42 in this embodiment) is located at the top, the communication hole 461 is located at the top inside the casing 41, so that the outside air that flows into the second chamber S2 passes around the electrical equipment unit 420 (electrical equipment 42 in this case). This can promote the flow of the outside air around the electrical equipment unit 420 (electrical equipment 42 in this case) into the first chamber S1. This prevents the leaked first refrigerant from flowing around the electrical equipment 42.

In addition, if the first refrigerant leaks, the first refrigerant above the lower end 451 of the cylindrical portion of the bell mouth 45 passes through the cylindrical portion of the bell mouth 45 and the outlet of the casing 41 and is discharged outside the casing 41.

(4) Features (4-1)
The outdoor unit 2 as an air conditioning unit according to this embodiment includes an electrical equipment unit 420, a first heat exchanger 12, a second heat exchanger 23, a fan 44, a casing 41, and a partition plate 46. The first heat exchanger 12 exchanges heat between a combustible first refrigerant and air. The second heat exchanger 23 exchanges heat between a non-combustible second refrigerant and air. The fan 44 passes air through the first heat exchanger 12 and the second heat exchanger 23. The casing 41 houses the electrical equipment unit 420, the first heat exchanger 12, the second heat exchanger 23, and the fan 44. The partition plate 46 divides the inside of the casing 41 into a first chamber S1 in which the first heat exchanger 12, the second heat exchanger 23, and the fan 44 are arranged, and a second chamber S2 in which the electrical equipment unit 420 is arranged. The partition plate 46 has a communication hole 461 that connects the first chamber S1 and the second chamber S2 above the first brazed portion 121, which is the uppermost of the multiple brazed portions 120 of the first heat exchanger 12.

In the outdoor unit 2 as the air conditioning unit of this embodiment, the communication hole 461 provided in the partition plate 46 and the fan 44 provided in the first chamber S1 allow air to flow from the second chamber S2 in which the electrical equipment unit 420 is arranged to the first chamber S1 in which the first heat exchanger 12 through which the first refrigerant flows is arranged. The communication hole 461 is provided at a position P1 higher than the first brazed portion 121 at the highest position P2 of the first heat exchanger 12 through which the flammable first refrigerant flows, so that even if the first refrigerant leaks in the first chamber S1, the first refrigerant can be prevented from flowing above the communication hole 461. Therefore, the possibility of ignition caused by the electrical equipment unit 420 in the second chamber S2 as an ignition source can be reduced. This air conditioning unit is particularly useful in the case of a highly flammable (A3) refrigerant such as R290.

(4-2)
The outdoor unit 2 as an air conditioning unit according to this embodiment is the outdoor unit 2 described above in (4-1), and the communication hole 461 is a hole for guiding air around the electrical component unit 420 to the fan.

Here, the air around the electrical equipment unit 420, which is a potential ignition source, is guided to the first chamber S1 through the communication hole 461, so that even if the first refrigerant leaks, the first refrigerant is prevented from flowing around the electrical equipment unit 420.

(4-3)
The outdoor unit 2 as an air conditioning unit according to this embodiment is the outdoor unit 2 of (4-1) or (4-2) above, and further includes a bellmouth 45. The bellmouth 45 is disposed in the first chamber S1, and has a cylindrical portion surrounding the fan 44. A lower end 431 of the electrical component unit 420 is located above a lower end 451 of the cylindrical portion.

Here, the fan 44 is disposed inside the cylindrical portion of the bell mouth 45. Normally, the first refrigerant is heavier than air, so even if the first refrigerant leaks, the first refrigerant will remain below the lower end 451 of the cylindrical portion. In this embodiment, the lower end 431 of the electrical equipment unit 420 (specifically, the board 43 on which the electrical equipment 42 is mounted) is located above the lower end 451 of the cylindrical portion. Therefore, even if there is a gap between the lower end of the partition plate 46 and the bottom plate 413 of the casing 41 and the first refrigerant goes into the second chamber S2, the first refrigerant that has accumulated below can be prevented from reaching the height level of the electrical equipment unit 420.

(4-4)
The outdoor unit 2 serving as an air conditioning unit according to this embodiment is any one of the outdoor units 2 described above in (4-1) to (4-3), in which the electrical component unit 420 is positioned above the first brazed portion 121.

Here, even if the first refrigerant leaks, the first refrigerant will remain below the first brazed portion 121. Here, because the electrical equipment unit 420 is located above the first brazed portion 121, the first refrigerant can be further prevented from flowing to the electrical equipment.

(4-5)
The outdoor unit 2 as an air conditioning unit according to this embodiment is any one of the outdoor units 2 described above in (4-1) to (4-4), in which the first heat exchanger 12 is positioned below the second heat exchanger 23.

Here, the first heat exchanger 12, through which the flammable refrigerant flows, is positioned below the second heat exchanger 23, through which the non-flammable refrigerant flows. Therefore, even if the first refrigerant leaks, the first refrigerant is likely to remain below, and since the distance between the communication hole 461 and the first brazed portion 121 can be secured, it is easy to realize an outdoor unit 2 that prevents the first refrigerant from flowing into the electrical equipment unit 420.

(4-6)
The outdoor unit 2 as an air conditioning unit according to this embodiment is the outdoor unit 2 according to any one of (4-1) to (4-5) above, and further includes a first compressor 11, a second compressor 21, and a bell mouth 45. The first compressor 11 is disposed in the second chamber S2 and compresses a first refrigerant. The second compressor 21 is disposed in the second chamber S2 and compresses a second refrigerant. The bell mouth 45 is disposed in the first chamber S1 and has a cylindrical portion surrounding the fan 44. The first terminal 111 of the first compressor 11 and the second terminal 211 of the second compressor 21 are located above a lower end 451 of the cylindrical portion.

Here, even if the first refrigerant leaks, the first refrigerant remains below the lower end 451 of the cylindrical portion of the bell mouth 45. Here, the first terminal 111 and the second terminal 211 are located above the lower end 451 of the cylindrical portion, so the possibility of ignition caused by the first terminal 111 and the second terminal 211 of the second chamber S2 as an ignition source can be reduced.

(4-7)
The outdoor unit 2 as an air conditioning unit according to this embodiment is any one of the outdoor units 2 described above in (4-1) to (4-5), and the second refrigerant contains carbon dioxide.

Since carbon dioxide refrigerant has a low GWP (global warming potential), it is possible to create an outdoor unit 2 that contributes more to reducing global warming.

(5) Modifications (5-1) Modification 1
In the above embodiment, the air conditioning unit is the outdoor unit 2 of the cascade refrigeration cycle apparatus 1, but is not limited thereto. The air conditioning unit of the present disclosure may be an indoor unit or a cascade unit.

(5-2) Modification 2
In the above embodiment, the cascade refrigeration cycle apparatus 1 in which one indoor unit 3 is connected to one outdoor unit 2 has been described as an example, but is not limited thereto. In the cascade refrigeration cycle apparatus of this modified example, multiple indoor units are connected to one outdoor unit.

(5-3) Modification 3
In the above embodiment, the air conditioning unit of the cascade refrigeration cycle apparatus 1 performing cooling operation and heating operation has been described as an example, but the present invention is not limited thereto. The cascade refrigeration cycle apparatus including the air conditioning unit of the present disclosure may further perform a dehumidification operation. In addition, the cascade refrigeration cycle apparatus including the air conditioning unit of the present disclosure may be an air conditioner dedicated to cooling.

Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the present disclosure as set forth in the claims.

1: Dual refrigeration cycle device 2: Outdoor unit (air conditioning unit)
3: Indoor unit 11: First compressor 12: First heat exchanger 21: Second compressor 23: Second heat exchanger 25: Third heat exchanger 30: Cascade heat exchanger 41: Casing 42: Electrical components 43: Board 44: Fan 45: Bell mouth 46: Partition plate 111, 211: Terminal 120: Brazed portion 121: First brazed portion 420: Electrical component unit 431, 451: Lower end 461: Communication hole S1: First chamber S2: Second chamber

Patent No. 5430604

Claims (5)

An electrical equipment unit (420);
a first heat exchanger (12) for exchanging heat between a combustible first refrigerant and air;
a second heat exchanger (23) for exchanging heat between a non-flammable second refrigerant and air;
a fan (44) for blowing air through the first heat exchanger and the second heat exchanger;
a casing (41) that houses the electrical equipment unit, the first heat exchanger, the second heat exchanger, and the fan;
a partition plate (46) that divides the inside of the casing into a first chamber (S1) in which the first heat exchanger, the second heat exchanger, and the fan are disposed, and a second chamber (S2) in which the electrical equipment unit is disposed;
Equipped with
The partition plate is provided with a communication hole (461) that communicates the first chamber with the second chamber, above a first brazed portion (121) that is located at the uppermost position among the plurality of brazed portions (120) of the first heat exchanger ,
The first heat exchanger is located below the second heat exchanger .
Air conditioning unit (2). The communication hole is a hole for guiding air around the electrical equipment unit to the fan.
2. An air conditioning unit according to claim 1. The fan further includes a bell mouth (45) disposed in the first chamber and having a cylindrical portion surrounding the fan,
The lower end (431) of the electrical equipment unit is located above the lower end (451) of the cylindrical portion.
An air conditioning unit according to claim 1 or 2. A lower end (431) of the electrical equipment unit is located above the first brazed portion.
An air conditioning unit according to claim 1 or 2. a first compressor (11) disposed in the second chamber and compressing the first refrigerant;
a second compressor (21) disposed in the second chamber and compressing the second refrigerant;
A bellmouth (45) disposed in the first chamber and having a cylindrical portion surrounding the fan;
Further equipped with
The terminal (111) of the first compressor and the terminal (211) of the second compressor are located above the lower end (451) of the cylindrical portion.
An air conditioning unit according to claim 1 or 2.

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