Refrigeration cycle device

Abstract

To improve maintainability.SOLUTION: A refrigeration cycle device (1) includes a first circuit (10), a second circuit (20), and a cascade heat exchanger (30). The first circuit (10) includes a first compressor (11), a first heat exchanger (12), and a first expansion mechanism (13) . In the first circuit (10), a first refrigerant circulates. The second circuit (20) includes a second compressor (21), a second heat exchanger (23), a second expansion mechanism (24) and a third heat exchanger (25). In the second circuit (20), a second refrigerant circulates. The cascade heat exchanger (30) performs heat exchange between the first refrigerant of the first circuit (10) and a second refrigerant of the second circuit (20). The refrigeration cycle device (1) is constituted so that the first circuit (10) and the cascade heat exchanger (30) can be removed from the second circuit (20).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] This relates to a refrigeration cycle device. [Background technology]

[0002] Patent Document 1 (Patent No. 5430604) discloses that in a dual-stage 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, the evaporator of the high-stage refrigeration cycle and the condenser of the low-stage refrigeration cycle exchange heat with each other using a cascade condenser. Patent Document 1 discloses that the high-stage refrigeration cycle uses HC refrigerants, HFC refrigerants, HFO refrigerants, etc. Summary of the Invention [Problem to be solved by the invention]

[0003] However, when the refrigerant used in the high-temperature refrigeration cycle is flammable, attention must be paid to maintenance. [Means for solving the problem]

[0004] A refrigeration cycle device according to a first aspect includes a first circuit, a second circuit, and a cascade heat exchanger. The first circuit includes a first compressor, a first heat exchanger, and a first expansion mechanism. A first refrigerant circulates through the first circuit. The second circuit includes a second compressor, a second heat exchanger, a second expansion mechanism, and a third heat exchanger. A second refrigerant circulates through the second circuit. The cascade heat exchanger exchanges heat between the first refrigerant of the first circuit and the second refrigerant of the second circuit. The refrigeration cycle device is configured such that the first circuit and the cascade heat exchanger can be removed from the second circuit.

[0005] In the refrigeration cycle apparatus of the first aspect, the first circuit and the cascade heat exchanger are configured to be removable from the second circuit, and therefore, by removing the first circuit during maintenance, it is possible to improve maintainability regardless of the type of the first refrigerant.

[0006] A refrigeration cycle apparatus according to a second aspect is the refrigeration cycle apparatus according to the first aspect, wherein components constituting the second circuit are disposed outside a space from which the first circuit and the cascade heat exchanger are removed.

[0007] In the refrigeration cycle apparatus of the second aspect, since there are no components constituting the second circuit in the path along which the first circuit and the cascade heat exchanger are removed, the first circuit and the cascade heat exchanger can be easily removed from the second circuit.

[0008] A refrigeration cycle apparatus according to a third aspect is the refrigeration cycle apparatus according to the first or second aspect, wherein the second circuit further includes a mechanical joint that connects the cascade heat exchanger and a pipe of the second circuit.

[0009] In the refrigeration cycle apparatus of the third aspect, since the second circuit is provided with a mechanical joint for connecting to the cascade heat exchanger, the cascade heat exchanger and the first circuit connected to the cascade heat exchanger can be easily separated from the piping of the second circuit by the mechanical joint. Furthermore, by using the mechanical joint, the first circuit and the cascade heat exchanger can be removed from the second circuit without using fire, thereby improving safety.

[0010] A refrigeration cycle apparatus according to a fourth aspect is the refrigeration cycle apparatus according to the third aspect, further comprising a casing. The casing houses the first circuit, the second compressor, the second heat exchanger, the second expansion mechanism, and the cascade heat exchanger. The mechanical joint is located on the outside within the casing.

[0011] In the refrigeration cycle apparatus of the fourth aspect, the mechanical joint for removing the cascade heat exchanger from the second circuit is disposed at the end portion, so that the work on the mechanical joint is easy.

[0012] A refrigeration cycle apparatus according to a fifth aspect is the refrigeration cycle apparatus according to the third or fourth aspect, in which the cascade heat exchanger is connected only to the piping of the second circuit by a mechanical joint.

[0013] In the refrigeration cycle apparatus of the fifth aspect, the cascade heat exchanger is not mechanically connected to the piping of the first circuit, so that it is possible to prevent the piping of the first circuit from being opened during maintenance.

[0014] A refrigeration cycle apparatus according to a sixth aspect is the refrigeration cycle apparatus according to the first aspect to the fifth aspect, further comprising a casing. The casing houses the first circuit, the second compressor, the second heat exchanger, the second expansion mechanism and the cascade heat exchanger. The casing includes a first bottom plate and a second bottom plate. The first bottom plate is configured to dispose the first compressor. The second bottom plate is a separate member from the first bottom plate. The second bottom plate is configured to dispose the second compressor.

[0015] In the refrigeration cycle apparatus of the sixth aspect, the first compressor of the first circuit and the second compressor of the second circuit are arranged on different bottom plates, so that the first circuit including the first compressor can be easily removed from the second circuit during maintenance.

[0016] A seventh aspect of the present invention is a refrigeration cycle apparatus according to any one of the first to sixth aspects, further comprising a casing. The casing houses the first circuit, the second compressor, the second heat exchanger, the second expansion mechanism, and the cascade heat exchanger. Within the casing, the first heat exchanger is positioned outside the second heat exchanger.

[0017] In the refrigeration cycle apparatus of the seventh aspect, the first heat exchanger is disposed at an end closer to the end than the second heat exchanger. Therefore, during maintenance, the first circuit including the first heat exchanger can be easily removed from the second circuit.

[0018] The refrigeration cycle apparatus of an eighth aspect is the refrigeration cycle apparatus of any one of the first aspect to the seventh aspect, further comprising a casing. The casing houses the first circuit, the second compressor, the second heat exchanger, the second expansion mechanism, and the cascade heat exchanger. The cascade heat exchanger is located on the outside within the casing.

[0019] In the refrigeration cycle apparatus of the eighth aspect, the cascade heat exchanger is disposed at the end portion, and therefore the cascade heat exchanger can be easily removed from the second circuit during maintenance.

[0020] A refrigeration cycle apparatus according to a ninth aspect is the refrigeration cycle apparatus according to any one of the first aspect to the eighth aspect, wherein the second refrigerant is a non-flammable refrigerant.

[0021] In the refrigeration cycle apparatus of the ninth aspect, since the second refrigerant is a non-flammable refrigerant, when a connection part for removing the cascade heat exchanger and the first circuit is provided in the second circuit, safety during maintenance can be increased. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic configuration diagram of a refrigeration cycle device according to an embodiment of the present disclosure. [Diagram 2] 1 is a schematic diagram of the outdoor unit as viewed from above with the top plate of the casing omitted. FIG. [Diagram 3] FIG. 2 is a diagram showing a state in which a first circuit and a cascade heat exchanger are removed from a second circuit in FIG. 1. [Figure 4] FIG. 3 is a diagram showing a state in which the first circuit and the cascade heat exchanger are removed from the second circuit in FIG. 2. [Diagram 5] FIG. 4 is a diagram showing the operation of the refrigeration cycle device in a heating operation. [Figure 6] FIG. 4 is a diagram showing the operation of the refrigeration cycle device in cooling operation. [Figure 7] 3 corresponds to FIG. 2 and is a schematic diagram of the outdoor unit of the first modified example in a state in which the top plate of the casing is omitted, as viewed from above. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] (1) Overall structure As shown in FIG. 1, a refrigeration cycle apparatus 1 according to an embodiment of the present disclosure is an apparatus used for cooling and heating a room in a building or the like by performing a vapor compression refrigeration cycle operation.

[0024] The refrigeration cycle device 1 includes a first circuit 10, a second circuit 20, and a cascade heat exchanger 30. The refrigeration cycle device 1 of the present embodiment has a binary refrigerant circuit consisting of the vapor compression first circuit 10 and the vapor compression second circuit 20, and performs a binary refrigeration cycle.

[0025] A first refrigerant circulates through the first circuit 10. A second refrigerant circulates through the second circuit 20. The cascade heat exchanger 30 thermally connects the first circuit 10 and the second circuit 20 together.

[0026] In the refrigeration cycle apparatus 1, the first circuit 10 and the cascade heat exchanger 30 are configured to be removable from the second circuit 20. In other words, the second circuit 20 is configured to be capable of being separated from the first circuit 10 and the cascade heat exchanger 30 without cutting the piping that constitutes the second circuit 20. Thus, in this embodiment, "removing" does not include separating the second circuit 20 from the first circuit 10 and the cascade heat exchanger 30 by cutting the piping.

[0027] The refrigeration cycle apparatus 1 includes an outdoor unit 2 and an indoor unit 3. The refrigeration cycle apparatus 1 is configured such that the outdoor unit 2 and the indoor unit 3 are connected to each other via communication pipes 4 and 5.

[0028] (2) Detailed configuration (2-1) 1st circuit The first refrigerant flowing through the first circuit 10 is not particularly limited, but is flammable or toxic here. The first refrigerant is, for example, a hydrocarbon refrigerant such as R1234yf, R1234ze, or R32, and is R290 in this embodiment.

[0029] The first circuit 10 constitutes a subcooling circuit during cooling operation. The first circuit is an assist circuit that assists the capacity of the second circuit 20 during cooling operation.

[0030] The first circuit 10 includes a first compressor 11, a first heat exchanger 12, and a first expansion mechanism 13.

[0031] The first compressor 11 is a device for compressing the first refrigerant, and is, for example, a positive displacement compressor such as a scroll type compressor whose operating capacity can be varied by inverter controlling the compressor motor.

[0032] 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 flat multi-hole pipe.

[0033] The first expansion mechanism 13 is a device that reduces the pressure of the first refrigerant, and is, for example, an electric expansion valve.

[0034] (2-2) Second circuit The second refrigerant flowing through the second circuit 20 is not particularly limited and may be the same as the first refrigerant or may be different from the first refrigerant. Here, the second refrigerant is non-flammable or non-toxic. The second refrigerant is, for example, a natural refrigerant, and in this embodiment, is carbon dioxide.

[0035] The second circuit 20 is a main circuit configured to heat or cool indoor air with a second refrigerant.

[0036] The second circuit 20 includes a second compressor 21, a switching mechanism 22, a second heat exchanger 23, a second expansion mechanism 24, a third heat exchanger 25, an accumulator 26, mechanical couplings 27, 28, and a shutoff valve 29.

[0037] The second compressor 21 is a device for compressing the second refrigerant, and is, for example, a positive displacement compressor such as a scroll type compressor whose operating capacity can be varied by inverter controlling the compressor motor.

[0038] 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.

[0039] 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 cross fin tube type heat exchanger.

[0040] The second expansion mechanism 24 is a device that reduces the pressure of the second refrigerant, and is, for example, an electric expansion valve.

[0041] 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 heat exchanger.

[0042] The accumulator 26 is provided in the middle of the suction flow passage that connects the switching mechanism 22 and the suction side of the second compressor 21. The accumulator 26 separates the flowing refrigerant into liquid refrigerant and gas refrigerant, and allows only the gas refrigerant to flow to the suction side of the second compressor 21.

[0043] The mechanical joints 27, 28 connect the cascade heat exchanger 30 and the piping of the second circuit 20. Here, the mechanical joint 27 is provided on the piping that connects the second heat exchanger 23 and a second flow path 32 (described later) of the cascade heat exchanger 30. The mechanical joint 28 is provided on the piping that connects the second flow path 32 (described later) of the cascade heat exchanger 30 and the second expansion mechanism 24.

[0044] The mechanical joints 27, 28 are components that mechanically connect pipes. Therefore, the mechanical joints 27, 28 are pipe joints that can be attached and removed without using fire and do not require welding. The mechanical joints 27, 28 are, for example, flare type, screw type, union type, flange type, bite type, housing type, etc.

[0045] The mechanical joints 27 , 28 are connections for removing the cascade heat exchanger 30 and the first circuit 10 from the second circuit 20 .

[0046] The shutoff valve 29 is provided at the connection between the outdoor unit 2 and the connection pipes 4, 5. The shutoff valve 29 is a valve that is manually opened and closed.

[0047] (2-3) Cascade heat exchanger The cascade heat exchanger 30 exchanges heat between the first refrigerant in the first circuit 10 and the second refrigerant in the second circuit 20. In other words, the cascade heat exchanger 30 is a device for exchanging heat between the first refrigerant and the second refrigerant without mixing them with each other. The cascade heat exchanger 30 is, for example, a plate type heat exchanger.

[0048] The cascade heat exchanger 30 has a first flow path 31 belonging to the first circuit 10 and a second flow path 32 belonging to the second circuit 20. The first flow path 31 has a gas side connected to the first compressor 11 and a liquid side connected to the first expansion mechanism 13. In the second state, the second flow path 32 has a gas side connected to the second heat exchanger 23 and a liquid side connected to the third heat exchanger 25.

[0049] The cascade heat exchanger 30 is connected only to the piping of the second circuit 20 by mechanical joints 27, 28. In other words, the cascade heat exchanger 30 is not mechanically connected to the piping of the first circuit 10. In other words, the cascade heat exchanger 30 is configured so that it cannot be removed from the second circuit 20.

[0050] When the first heat exchanger 12 is used as a radiator and the second heat exchanger 23 of the second circuit 20 is used as a radiator, the cascade heat exchanger 30 has the purpose of supercooling the second refrigerant cooled in the second heat exchanger 23, and plays the role of assisting the second circuit 20.

[0051] (2-4) Outdoor unit In the following description, expressions indicating directions such as "up", "down", and "front" are used as appropriate, and these indicate the directions when the outdoor unit 2 is installed outdoors and in normal use. In this embodiment, the up and down direction is the vertical direction.

[0052] The outdoor unit 2 is disposed in a space different from the space in which the indoor unit 3 is disposed. Here, the outdoor unit 2 is installed outdoors (on the roof of a building, near the exterior wall surface of a building, etc.).

[0053] The outdoor unit 2 has the above-mentioned first circuit 10, a part of the second circuit 20, a casing 41, a first fan 42, a second fan 43, a first partition plate 44, and a second partition plate 45. 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 accumulator 26, the mechanical joints 27 and 28, the cascade heat exchanger 30, and the casing 41, the first fan 42, the second fan 43, the first partition plate 44, and the second partition plate 45 shown in FIG.

[0054] The first fan 42 causes the outdoor air to flow through the first heat exchanger 12. The second fan 43 causes the outdoor air to flow through the second heat exchanger 23. The first fan 42 and the second fan 43 are driven by fan motors.

[0055] The casing 41 accommodates the first circuit 10, the second compressor 21, the switching mechanism 22, the second heat exchanger 23, the second expansion mechanism 24, the mechanical joints 27, 28, the stop valve 29, and the cascade heat exchanger 30. Here, the casing 41 accommodates 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 accumulator 26, the mechanical joints 27, 28, the cascade heat exchanger 30, the first fan 42, the second fan 43, the first partition plate 44, and the second partition plate 45.

[0056] 2 has a substantially rectangular parallelepiped shape. Specifically, the casing 41 includes a front plate 411, a top plate (not shown), a bottom plate 412, and side plates 413.

[0057] The front plate 411 is a plate-like member that constitutes 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 out the outdoor air taken in from the outside of the casing 41 to the inside of the casing 41 to the outside of the casing 41. The top plate is a plate-like member that constitutes the upper surface of the casing 41.

[0058] The bottom plate 412 is a plate-like member that constitutes the lower surface of the casing 41. The top plate and the bottom plate 412 face each other.

[0059] The bottom plate 412 has a first bottom plate 412a and a second bottom plate 412b. The first bottom plate 412a and the second bottom plate 412b are separate members and can be separated. The first bottom plate 412a is arranged with the first compressor 11. The second bottom plate 412b is arranged with the second compressor 21. Here, the first compressor 11, the first heat exchanger 12, the first expansion mechanism 13, the first fan 42, and the cascade heat exchanger 30 are located above the first bottom plate 412a. The second compressor 21, the switching mechanism 22, the second heat exchanger 23, the second expansion mechanism 24, the accumulator 26, the mechanical joints 27 and 28, and the second fan 43 are located above the second bottom plate 412b.

[0060] The side plate 413 is a plate-like member that constitutes the side surface of the casing 41. The lower portion of the side plate 413 is fixed to the bottom plate 412.

[0061] The first partition plate 44 and the second partition plate 45 are plate-shaped members extending in the vertical direction. The lower portions of the first partition plate 44 and the second partition plate 45 are fixed to the bottom plate 412 of the casing 41.

[0062] The first partition plate 44 divides the inside of the casing 41 into a first chamber S1 and a second chamber S2. The second partition plate 45 divides the inside of the casing 41 into a second chamber S2 and a third chamber S3.

[0063] The first chamber S1 is defined by the front plate 411, the top plate, the second bottom plate 412b, and the first partition plate 44. The second chamber S2 is defined by the front plate 411, the top plate, the second bottom plate 412b, the first partition plate 44, and the second partition plate 45. The third chamber S3 is defined by the front plate 411, the top plate, the first bottom plate 412a, the second partition plate 45, and the side plate 413.

[0064] The first chamber S1 is an air blowing chamber of the second circuit 20, and is an air guide passage through which air drawn in from an inlet of the outdoor unit 2 flows to an outlet. The second heat exchanger 23, the second fan 43, etc. are disposed in the first chamber S1.

[0065] The second chamber S2 is a machine chamber for the second circuit 20. In the second chamber S2, the second compressor 21, the switching mechanism 22, the accumulator 26, the mechanical joints 27, 28, etc. are disposed.

[0066] The third chamber S3 is arranged with the first circuit 10 and the cascade heat exchanger 30. Specifically, the third chamber S3 is arranged with the first compressor 11, the first heat exchanger 12, the first expansion mechanism 13, the cascade heat exchanger 30, etc.

[0067] The mechanical joints 27, 28, the first heat exchanger 12, and the cascade heat exchanger 30 are provided in positions within the casing 41 that allow easy work for an operator. Here, the mechanical joints 27, 28, the first heat exchanger 12, and the cascade heat exchanger 30 are located on the outside within the casing 41. In FIG. 2, the first heat exchanger 12 and the cascade heat exchanger 30 are disposed on the outermost surface within the casing 41. Also, the first heat exchanger 12 is located outside the second heat exchanger 23.

[0068] 3 and 4, the first circuit 10 and the cascade heat exchanger 30 can be removed from the second circuit 20 at the mechanical joints 27, 28. Here, by disconnecting the cascade heat exchanger 30 from the piping of the second circuit 20 at the mechanical joints 27, 28, the first chamber S1 and the second chamber S2 can be separated from the third chamber S3.

[0069] The components constituting the second circuit 20 are arranged outside the space where the first circuit 10 and the cascade heat exchanger 30 are removed. In other words, there are no components constituting the second circuit 20 on the path of removing the first circuit 10 and the cascade heat exchanger 30. For this reason, the piping of the first circuit 10 and the piping of the second circuit 20 are not entangled. Here, the third chamber S3 in which the first compressor 11, the first heat exchanger 12, the first expansion mechanism 13, the first fan 42, and the cascade heat exchanger 30 are arranged is a space separate from the first chamber S1 in which the second heat exchanger 23 and the second fan 43 are arranged, and the second chamber S2 in which the second compressor 21, the switching mechanism 22, the second expansion mechanism 24, the accumulator 26, the mechanical joints 27, 28, and the closing valve 29 are arranged.

[0070] (2-5) 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 connection pipes 4 and 5, and constitutes a part of the second circuit 20.

[0071] 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 from a ceiling in a room of a building or the like, or by hanging from a wall surface in the room.

[0072] (2-6) Connecting piping The connecting pipes 4, 5 are refrigerant pipes that are installed on-site when the refrigeration cycle apparatus 1 is installed in an installation location such as a building. One end of the liquid side connecting pipe 4 is connected to a liquid side end of the outdoor unit 2, and the other end of the connecting pipe 4 is connected to a liquid side end of the third heat exchanger 25 of the indoor unit 3. One end of the gas side connecting pipe 5 is connected to a gas side end of the outdoor unit 2, and the other end of the connecting pipe 5 is connected to a gas side end of the third heat exchanger 25 of the indoor unit 3.

[0073] (2-7) Control section The components of the outdoor unit 2 and the indoor unit 3 are controlled by a control unit 6. The control unit 6 is configured by communication connection with an electrical equipment unit etc. provided in the outdoor unit 2 and a 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 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 refrigeration cycle apparatus 1.

[0074] The control unit 6 is realized by a computer. The control unit 6 includes a control arithmetic device and a storage device. The control arithmetic device can be a processor such as a CPU or a GPU. The control arithmetic device reads out a program stored in the storage device, and performs predetermined image processing and arithmetic processing according to the program. Furthermore, the control arithmetic device can write the results of the calculations to the storage device and read out information stored in the storage device according to the program.

[0075] (3) Operation The operation of the refrigeration cycle apparatus 1 will be described with reference to Fig. 1 to Fig. 6. The refrigeration cycle apparatus 1 is capable of performing a heating operation for heating indoor air and a cooling operation for cooling indoor air for air conditioning. In the heating operation and the cooling operation, the operation of the refrigeration cycle apparatus 1 is controlled by a control unit 6.

[0076] (3-1) Heating operation 5, during heating operation, the switching mechanism 22 is switched to the second state (the state in which the switching mechanism 22 is in the dashed 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 circuit 10.

[0077] In the second circuit 20, the second refrigerant discharged from the second compressor 21 flows out of the outdoor unit 2 through the switching mechanism 22.

[0078] 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 is cooled by exchanging heat with the indoor air, thereby releasing heat. The second refrigerant that has released heat in the third heat exchanger 25 flows out of the indoor unit 3.

[0079] 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 outdoor air supplied by the fan 43 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 and the accumulator 26.

[0080] (3-2) Cooling operation As shown in FIG. 6, during cooling operation, the switching mechanism 22 is switched to the first state (the state in which the switching mechanism 22 is indicated by 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.

[0081] In the second circuit 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 exchanging heat with the outdoor air supplied by the fan 43, thereby dissipating 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 exchanging heat 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.

[0082] 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 is heated through heat exchange with the indoor air and evaporates. The second refrigerant that has evaporated in the third heat exchanger 25 flows out of the indoor unit 3.

[0083] The second refrigerant that flows out of the indoor unit 3 passes through the gas side communication pipe 5 and flows into the outdoor unit 2. In the outdoor unit 2, the second refrigerant passes through the switching mechanism 22 and the accumulator 26 and is sucked into the second compressor 21 again.

[0084] In the first circuit 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 43, and dissipates heat. The first refrigerant that has dissipated heat 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 through the second flow path 32 in the cascade heat exchanger 30, and thereby evaporates. The first refrigerant that has evaporated in the cascade heat exchanger 30 is sucked back into the first compressor 11.

[0085] (3-3) During maintenance The operation during maintenance will be described with reference to Figs. 1 to 4. As described above, the first circuit 10 and the cascade heat exchanger 30 are configured to be removable from the second circuit 20. Therefore, during maintenance, the second circuit 20 is separated from the first circuit 10 and the cascade heat exchanger 30. In this embodiment, the entire first circuit 10 and the cascade heat exchanger 30 are removed from the second circuit 20 during maintenance.

[0086] Specifically, first, a hose for the second refrigerant is connected to the stop valve 29 shown in FIG. 1, and the second refrigerant is discharged to the atmosphere. Next, the mechanical joints 27 and 28 are removed to separate the second circuit 20 from the first circuit 10 and the cascade heat exchanger 30 from the state shown in FIG. 1 and FIG. 2 to the state shown in FIG. 3 and FIG. 4. At this time, the components constituting the second circuit 20 are arranged outside the space from which the first circuit 10 and the cascade heat exchanger 30 are removed. Here, the third chamber S3 in which the components constituting the first circuit 10 and the cascade heat exchanger 30 are accommodated is located at one end of the casing 41. Therefore, the components constituting the first circuit 10 and the cascade heat exchanger 30 can be easily pulled out from the second circuit 20.

[0087] In this embodiment, when removing the first circuit 10 and the cascade heat exchanger 30 from the second circuit 20, the piping of the first circuit 10 is not opened, and only the piping of the second circuit 20 is opened. Here, since the second circuit 20 is filled with carbon dioxide, safety is ensured even if the piping of the second circuit 20 is opened. Therefore, even if the first refrigerant filling the first circuit 10 is flammable R290, the second circuit 20 can be separated from the first circuit 10 and the cascade heat exchanger 30 with improved safety.

[0088] (4) Features (4-1) The refrigeration cycle device 1 according to the present embodiment includes a first circuit 10, a second circuit 20, and a cascade heat exchanger 30. The first circuit 10 includes a first compressor 11, a first heat exchanger 12, and a first expansion mechanism 13. A first refrigerant circulates through the first circuit 10. The second circuit 20 includes a second compressor 21, a second heat exchanger 23, a second expansion mechanism 24, and a third heat exchanger 25. A second refrigerant circulates through the second circuit 20. The cascade heat exchanger 30 exchanges heat between the first refrigerant of the first circuit 10 and the second refrigerant of the second circuit 20. The refrigeration cycle device 1 is configured such that the first circuit 10 and the cascade heat exchanger 30 can be removed from the second circuit 20.

[0089] In the refrigeration cycle apparatus 1 of the present embodiment, the first circuit 10 and the cascade heat exchanger 30 are configured to be removable from the second circuit 20. Therefore, during maintenance, the first circuit 10 and the cascade heat exchanger 30 can be removed together, separated from the second circuit 20. Therefore, the second circuit 20 can be easily separated from the first circuit 10 and the cascade heat exchanger 30. In this way, by removing the first circuit 10 during maintenance, it is possible to improve maintainability regardless of the type of the first refrigerant.

[0090] (4-2) The refrigeration cycle apparatus 1 according to this embodiment is the refrigeration cycle apparatus 1 described above in (4-1), in which the components constituting the second circuit 20 are arranged outside the space from which the first circuit 10 and the cascade heat exchanger 30 are removed.

[0091] Here, since there are no components constituting the second circuit 20 in the path along which the first circuit 10 and the cascade heat exchanger 30 are removed, the first circuit 10 and the cascade heat exchanger 30 can be easily removed from the second circuit 20.

[0092] (4-3) The refrigeration cycle apparatus 1 according to this embodiment is the refrigeration cycle apparatus 1 described above in (4-1) or (4-2), and the second circuit 20 further includes mechanical joints 27, 28 that connect the cascade heat exchanger 30 and the piping of the second circuit 20.

[0093] Here, mechanical joints 27, 28 are provided in the second circuit 20 for connecting it to the cascade heat exchanger 30, so that the first circuit 10 and the cascade heat exchanger 30 connected to the cascade heat exchanger 30 can be easily separated from the piping of the second circuit 20 by the mechanical joints 27, 28.

[0094] Furthermore, by using the mechanical joints 27, 28, the first circuit 10 and the cascade heat exchanger 30 can be removed from the second circuit 20 without using fire. For example, even if the first refrigerant is a flammable refrigerant, the piping of the second circuit 20 can be removed near the piping of the first circuit 10 without using fire. This improves safety.

[0095] Furthermore, since the first circuit 10 and the cascade heat exchanger 30 can be removed from the second circuit 20 for maintenance without using fire, the generation of soot that accompanies the use of fire can be prevented. As a result, when attaching the first circuit 10 and the cascade heat exchanger 30 to the second circuit 20 after maintenance, there is no need to consider soot that has adhered thereto, which further improves maintainability.

[0096] (4-4) The refrigeration cycle apparatus 1 according to this embodiment is the refrigeration cycle apparatus 1 of (4-3) above, and further includes a casing 41. The casing 41 houses the first circuit 10, the second compressor 21, the second heat exchanger 23, the second expansion mechanism 24, and the cascade heat exchanger 30. The mechanical joints 27, 28 are located on the outside within the casing.

[0097] Here, the mechanical joints 27, 28 for removing the cascade heat exchanger 30 from the second circuit 20 are arranged at the ends, making it easy to work on the mechanical joints 27, 28.

[0098] (4-5) The refrigeration cycle apparatus 1 according to this embodiment is the refrigeration cycle apparatus 1 of the above (4-3) or (4-4), in which the cascade heat exchanger 30 is connected only to the piping of the second circuit 20 by mechanical joints 27, .

[0099] Here, since the cascade heat exchanger 30 is not mechanically connected to the piping of the first circuit 10, it is possible to prevent the piping of the first circuit 10 from being opened during maintenance. Therefore, in cases where the first refrigerant is flammable or toxic, it is possible to improve safety during maintenance.

[0100] (4-6) The refrigeration cycle apparatus 1 according to this embodiment is the refrigeration cycle apparatus 1 according to the above (4-1) to (4-5), and further includes a casing 41. The casing 41 houses the first circuit 10, the second compressor 21, the second heat exchanger 23, the second expansion mechanism 24, and the cascade heat exchanger 30. The casing 41 includes a first bottom plate 412a and a second bottom plate 412b. The first bottom plate 412a accommodates the first compressor 11. The second bottom plate 412b is a member separate from the first bottom plate 412a. The second bottom plate 412b accommodates the second compressor 21.

[0101] Here, the first compressor 11 of the first circuit 10 and the second compressor 21 of the second circuit 20 are arranged on a first bottom plate 412a and a second bottom plate 412b, which are different from each other, so that the first circuit 10 including the first compressor 11 can be easily removed from the second circuit 20 during maintenance.

[0102] (4-7) The refrigeration cycle apparatus 1 according to this embodiment is the refrigeration cycle apparatus 1 described above in (4-1) to (4-6), and further includes a casing 41. The casing 41 houses the first circuit 10, the second compressor 21, the second heat exchanger 23, the second expansion mechanism 24, and the cascade heat exchanger 30. Within the casing 41, the first heat exchanger 12 is located outside the second heat exchanger 23.

[0103] Here, since the first heat exchanger 12 is disposed closer to the end than the second heat exchanger 23, a wide path can be secured for removing the first circuit 10 and the cascade heat exchanger 30 during maintenance. Therefore, the first circuit 10 including the first heat exchanger 12 can be easily removed from the second circuit 20.

[0104] (4-8) The refrigeration cycle apparatus 1 according to this embodiment is the refrigeration cycle apparatus 1 described above in (4-1) to (4-7), and further includes a casing 41. The casing 41 houses the first circuit 10, the second compressor 21, the second heat exchanger 23, the second expansion mechanism 24, and the cascade heat exchanger 30. The cascade heat exchanger 30 is located on the outside within the casing 41.

[0105] Here, since the cascade heat exchanger 30 is disposed at the end, a wide path can be secured for removing the first circuit 10 and the cascade heat exchanger 30 during maintenance. Therefore, the cascade heat exchanger 30 can be easily removed from the second circuit 20.

[0106] (4-9) The refrigeration cycle apparatus 1 according to this embodiment is the refrigeration cycle apparatus 1 described above in (4-1) to (4-8), and the second refrigerant is a non-flammable refrigerant.

[0107] Here, since the second refrigerant is a non-flammable refrigerant, when mechanical joints 27, 28, which are connection parts for removing the cascade heat exchanger 30 and the first circuit 10, are provided in the second circuit 20, safety during maintenance can be increased.

[0108] (4-10) The refrigeration cycle apparatus 1 according to this embodiment is the refrigeration cycle apparatus 1 described above in (4-9), in which the first refrigerant is R290 and the second refrigerant is carbon dioxide.

[0109] Here, during maintenance, the first circuit 10, whose piping is not opened, is filled with R290, and the second circuit 20, whose piping is opened, is filled with carbon dioxide. This improves safety during maintenance.

[0110] In addition, since carbon dioxide refrigerant has a low GWP, it can contribute to reducing global warming, but it is difficult to achieve high capacity during cooling operation at high outdoor temperatures. In contrast, the refrigeration cycle device 1 of this embodiment is equipped with the first circuit 10, in which R290 circulates, as a subcooling circuit, and therefore can increase capacity.

[0111] (5) Variations (5-1) Variation 1 In the above embodiment, an example in which the components constituting the first circuit 10 are integrated into one unit has been described, but the present invention is not limited to this. In this modification, as shown in Fig. 7, the first heat exchanger 12 is disposed in the first chamber S1, which is the blowing chamber of the second circuit 20. Here, the first heat exchanger 12 is disposed near the second heat exchanger 23. The fan 43 that sends outdoor air to the first heat exchanger 12 and the second heat exchanger 23 is shared.

[0112] In this modified example as well, the first circuit 10 and the cascade heat exchanger 30 are configured to be removable from the second circuit 20. In FIG. 7, the first heat exchanger 12 and the third chamber S3 are separated from the second circuit 20.

[0113] (5-2) Variation 2 In the above embodiment, the mechanical joints 27, 28 are arranged in the second chamber S2, but are not limited to this, and may be arranged in the first chamber S1 or the third chamber S3.

[0114] (5-3) Variation 3 In the above embodiment, the cascade heat exchanger 30 is disposed in the third chamber S3, but is not limited to this, and may be disposed in the first chamber S1 or the second chamber S2.

[0115] (5-4) Variation 4 In the above embodiment, the heat source of the first heat exchanger 12 is outdoor air, but is not limited to this. In this modification, the heat source of the first heat exchanger 12 is water. In other words, the first heat exchanger 12 exchanges heat with water. In this case, the first heat exchanger 12 is, for example, a plate heat exchanger.

[0116] (5-5) Variation 5 In the above embodiment, the 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 refrigeration cycle apparatus of this modified example, multiple indoor units are connected to one outdoor unit.

[0117] (5-6) Variation 6 In the above embodiment, the refrigeration cycle device 1 performing the cooling operation and the heating operation has been described as an example, but is not limited thereto. The refrigeration cycle device of the present disclosure may further perform a dehumidification operation. In addition, the refrigeration cycle device of the present disclosure may be an air conditioner dedicated to cooling.

[0118] Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure described in the claims. [Explanation of symbols]

[0119] 1: Refrigeration cycle device 10:1st circuit 11: First compressor 12: 1st heat exchanger 13: First expansion mechanism 20: 2nd circuit 21: Second compressor 23:Second heat exchanger 24: Second expansion mechanism 25:Third heat exchanger 27, 28: Mechanical joints 30: Cascade heat exchanger 41: Casing 412a: 1st bottom plate 412b: 2nd bottom plate [Prior art documents] [Patent documents]

[0120] [Patent Document 1] Patent No. 5430604

Claims

1. a first circuit (10) including a first compressor (11), a first heat exchanger (12), and a first expansion mechanism (13), in which a first refrigerant circulates; a second circuit (20) including a second compressor (21), a second heat exchanger (23), a second expansion mechanism (24), and a third heat exchanger (25), in which a second refrigerant circulates; a cascade heat exchanger (30) for exchanging heat between the first refrigerant in the first circuit and the second refrigerant in the second circuit; Equipped with The refrigeration cycle apparatus (1) is configured so that the first circuit and the cascade heat exchanger can be removed from the second circuit.

2. The components constituting the second circuit are arranged outside a space from which the first circuit and the cascade heat exchanger are removed. The refrigeration cycle device according to claim 1.

3. the second circuit further includes mechanical couplings (27, 28) connecting the cascade heat exchanger and piping of the second circuit; The refrigeration cycle apparatus according to claim 1 or 2.

4. The compressor further includes a casing (41) that houses the first circuit, the second compressor, the second heat exchanger, the second expansion mechanism, and the cascade heat exchanger, The mechanical joint is located outside the casing. The refrigeration cycle device according to claim 3.

5. The cascade heat exchanger is connected only to the piping of the second circuit by the mechanical joint. The refrigeration cycle device according to claim 3.

6. The compressor further includes a casing (41) that houses the first circuit, the second compressor, the second heat exchanger, the second expansion mechanism, and the cascade heat exchanger, The casing comprises: A first bottom plate (412a) on which the first compressor is disposed; A second bottom plate (412b) which is a separate member from the first bottom plate and on which the second compressor is disposed; Including, The refrigeration cycle apparatus according to claim 1 or 2.

7. The compressor further includes a casing (41) that houses the first circuit, the second compressor, the second heat exchanger, the second expansion mechanism, and the cascade heat exchanger, In the casing, the first heat exchanger is located outside the second heat exchanger. The refrigeration cycle apparatus according to claim 1 or 2.

8. The compressor further includes a casing (41) that houses the first circuit, the second compressor, the second heat exchanger, the second expansion mechanism, and the cascade heat exchanger, The cascade heat exchanger is located externally within the casing. The refrigeration cycle apparatus according to claim 1 or 2.

9. The second refrigerant is a non-flammable refrigerant. The refrigeration cycle apparatus according to claim 1 or 2.

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