Refrigeration cycle device

Abstract

The invention provides a refrigeration cycle device capable of reducing the amount of refrigerant filling and achieving high operation efficiency. A refrigeration cycle device that executes a heating operation and a cooling operation, said refrigeration cycle device being provided with a compressor, a radiator, an internal heat exchanger, and an evaporator. The internal heat exchanger has a first heat transfer tube through which a refrigerant flowing from the evaporator to the compressor passes and a second heat transfer tube through which a refrigerant flowing from the radiator to the evaporator passes, and exchanges heat between the refrigerant passing through the first heat transfer tube and the refrigerant passing through the second heat transfer tube. The refrigerant does not flow through the second heat transfer tube.

Description

Technical Field

[0001] The present invention relates to a refrigeration cycle device. Background Art

[0002] Patent Document 1 (Japanese Patent Application Laid-Open No. 2013-21013) discloses an air conditioner equipped with an outdoor heat exchanger, an energy-saving heat exchanger, an internal heat exchanger, and an indoor heat exchanger, and capable of switching between cooling and heating operations. To improve operational efficiency, the air conditioner disclosed in Patent Document 1 suppresses refrigerant flow to the energy-saving heat exchanger and the internal heat exchanger during heating. Summary of the Invention

[0003] Problems to be solved by the invention

[0004] In a refrigeration cycle system equipped with an internal heat exchanger, as in the air conditioner disclosed in Patent Document 1, the amount of refrigerant filled in the refrigerant circuit (refrigerant filling amount) is determined by taking into account the capacity of the internal heat exchanger in addition to the capacity of the outdoor and indoor heat exchangers. Therefore, a refrigeration cycle system that achieves improved operating efficiency by including an internal heat exchanger tends to have a larger refrigerant filling amount than a refrigeration cycle system without an internal heat exchanger.

[0005] The present disclosure provides a refrigeration cycle device capable of achieving both reduction in refrigerant filling amount and high operation efficiency.

[0006] Means for solving problems

[0007] A refrigeration cycle device according to a first aspect performs a heating operation and a cooling operation. The refrigeration cycle device includes a compressor, a radiator, an evaporator, and an internal heat exchanger.

[0008] The internal heat exchanger includes a first heat transfer tube and a second heat transfer tube. The first heat transfer tube allows refrigerant flowing from the main heat exchanger, which functions as an evaporator, to pass through the compressor. The second heat transfer tube allows refrigerant flowing from the main heat exchanger, which functions as a radiator, to pass through the evaporator. The internal heat exchanger exchanges heat between the refrigerant passing through the first heat transfer tube and the refrigerant passing through the second heat transfer tube. During cooling operation, refrigerant does not flow through the second heat transfer tube.

[0009] Typically, the amount of refrigerant filled in a refrigerant circuit of a refrigeration cycle device including an internal heat exchanger (refrigerant filling amount) is calculated by adding the capacity of the heat exchanger functioning as a radiator of the refrigerant to the capacity of the internal heat exchanger.

[0010] In the internal heat exchanger of this refrigeration cycle device, refrigerant does not flow through the second heat transfer tube during cooling operation. Therefore, the refrigerant charge is calculated based solely on the capacity of the radiator during cooling operation, regardless of the capacity of the internal heat exchanger. Consequently, this refrigeration cycle device reduces the refrigerant charge compared to when the internal heat exchanger is functioning during cooling operation (in other words, when refrigerant is flowing through the second heat transfer tube).

[0011] A refrigeration cycle device according to a second aspect is the refrigeration cycle device according to the first aspect, further comprising a liquid refrigerant flow path, an injection flow path, a second decompression unit, an energy-saving heat exchanger, and a first valve.

[0012] The liquid refrigerant flow path connects the evaporator and the radiator. The injection flow path branches off from the liquid refrigerant flow path and merges with the compressor. The second decompression unit decompresses the refrigerant passing through the injection flow path. The energy-saving heat exchanger exchanges heat between the refrigerant decompressed by the second decompression unit and the refrigerant flowing from the radiator to the evaporator.

[0013] The present refrigeration cycle device has an energy-saving heat exchanger and can therefore operate at a higher efficiency.

[0014] A refrigeration cycle device according to a third aspect is the refrigeration cycle device according to the first aspect or the second aspect, wherein the refrigerant does not flow through the economizer heat exchanger during cooling operation.

[0015] Therefore, the refrigerant charge is calculated based solely on the capacity of the radiator during cooling operation, without considering the capacities of the internal heat exchanger and the energy-saving heat exchanger. Consequently, according to this refrigeration cycle device, the refrigerant charge is reduced compared to when the energy-saving heat exchanger is functioning during cooling operation. This allows the refrigeration cycle device to achieve both a reduced refrigerant charge and high operating efficiency.

[0016] A refrigeration cycle device according to a fourth aspect is the refrigeration cycle device according to any one of the first to third aspects, wherein during heating operation, the refrigerant flows through the internal heat exchanger and the economizer heat exchanger.

[0017] This refrigeration cycle device allows the internal heat exchanger and the energy-saving heat exchanger to function during heating operation, and thus can operate at a higher efficiency.

[0018] A refrigeration cycle device according to a fifth aspect is the refrigeration cycle device according to the second aspect, further comprising a first valve that restricts the flow of the refrigerant from the liquid refrigerant flow path to the economizer heat exchanger.

[0019] The first valve restricts the flow of refrigerant from the liquid refrigerant flow path to the economizer heat exchanger during cooling operation.

[0020] A refrigeration cycle device according to a sixth aspect is the refrigeration cycle device according to the fifth aspect, wherein the first valve is a valve that switches between an open state and a closed state.

[0021] A refrigeration cycle device according to a seventh aspect is the refrigeration cycle device according to the sixth aspect, wherein the first valve is closed during cooling operation.

[0022] The first valve restricts the flow of refrigerant from the liquid refrigerant flow path to the economizer heat exchanger during cooling operation.

[0023] A refrigeration cycle device according to an eighth aspect is the refrigeration cycle device according to any one of the first to seventh aspects, further comprising a second valve that restricts inflow of the refrigerant flowing through the injection flow path into the compressor.

[0024] The second valve can restrict the flow of refrigerant from the injection flow path to the compressor.

[0025] A refrigeration cycle device according to a ninth aspect is the refrigeration cycle device according to the eighth aspect, wherein the second valve is a valve that switches between an open state and a closed state.

[0026] A refrigeration cycle device according to a tenth aspect is the refrigeration cycle device according to the ninth aspect, wherein the second valve is in an open state during cooling operation.

[0027] By opening the second valve, the second heat transfer tubes of the economizer heat exchanger and the internal heat exchanger reach low pressure. As a result, when switching from heating to cooling operation, refrigerant remaining in the second heat transfer tubes of the economizer heat exchanger and the internal heat exchanger flows into the compressor and is recovered. Therefore, this refrigeration cycle device can prevent refrigerant shortages in the refrigerant circuit during cooling operation.

[0028] The refrigeration cycle device according to an eleventh aspect is the refrigeration cycle device according to any one of the first to tenth aspects, further including a first branch flow path 73 and a second branch flow path 74 branching from the liquid refrigerant flow path.

[0029] One end of the second heat transfer tube is connected to the end of the first branch flow path 73 opposite to the liquid refrigerant flow path, and the other end is connected to the end of the second branch flow path 74 opposite to the liquid refrigerant flow path.

[0030] The refrigeration cycle device according to a twelfth aspect is the refrigeration cycle device according to the eleventh aspect, further comprising a third valve that restricts the flow of the refrigerant from the liquid refrigerant flow path to the second heat transfer tube in the second branch flow path 74 .

[0031] The third valve suppresses the flow of refrigerant into the second heat transfer tube of the internal heat exchanger during cooling operation.

[0032] A refrigeration cycle device according to a thirteenth aspect In the refrigeration cycle device according to the twelfth aspect, the third valve is a check valve.

[0033] A refrigeration cycle device according to a fourteenth aspect is the refrigeration cycle device according to any one of the first to thirteenth aspects, further comprising a fourth valve. The fourth valve is a check valve that restricts the flow of refrigerant from a first branch portion, where the first branch flow path branches off from the liquid refrigerant flow path, to a second branch portion, where the second branch flow path branches off from the liquid refrigerant flow path.

[0034] The fourth valve promotes the flow of the refrigerant flowing out of the radiator into the first branch flow path during heating operation.

[0035] A refrigeration cycle device according to a fifteenth aspect In the refrigeration cycle device according to any one of the first to fourteenth aspects, the economizer heat exchanger exchanges heat between the refrigerant flowing in the injection flow path and the refrigerant flowing in the first branch flow path ( 73 ).

[0036] The energy-saving heat exchanger further dissipates heat from the refrigerant in the radiator during heating operation, thereby supercooling the refrigerant.

[0037] A refrigeration cycle device according to a sixteenth aspect is the refrigeration cycle device according to any one of the first to fifteenth aspects, wherein the refrigerant used in the refrigeration cycle device is a flammable refrigerant (propane).

[0038] According to this refrigeration cycle device, since the refrigerant filling amount is suppressed, even if refrigerant leakage occurs, the amount of leaked refrigerant can be suppressed. Therefore, according to this refrigeration cycle device, even when using a flammable refrigerant, accidents caused by leakage can be suppressed.

[0039] A refrigeration cycle device according to a seventeenth aspect is the refrigeration cycle device according to any one of the first to sixteenth aspects, further comprising a first decompression unit, a third branch flow path, a fifth valve, and a sixth valve.

[0040] The first decompression unit decompresses the refrigerant between the second branch portion and the third valve of the second branch flow path. The third branch flow path branches from the second branch flow path between the first decompression unit and the third valve and is connected to a portion of the liquid refrigerant flow path opposite the fourth valve across the second branch portion. The fifth valve restricts the flow of refrigerant from the connection portion of the third branch flow path to the second branch portion in the liquid refrigerant flow path. The sixth valve restricts the flow of refrigerant from the second branch flow path to the liquid refrigerant flow path in the third branch flow path.

[0041] The fifth and sixth valves are disposed on a refrigerant flow path extending from the upstream side of the first decompression unit to the downstream side via the third branch flow path. Therefore, the fifth and sixth valves reliably operate by utilizing the refrigerant pressure difference generated between the upstream and downstream sides of the first decompression unit, thereby suppressing undesirable refrigerant flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the refrigeration cycle device.

[0043] Figure 2 It is a block diagram of the control unit 100.

[0044] Figure 3 It is a diagram for explaining the flow of the refrigerant during the heating operation of the refrigeration cycle device 1 .

[0045] Figure 4 It is a diagram for explaining the flow of the refrigerant during the cooling operation of the refrigeration cycle device 1 .

[0046] Figure 5 It is a schematic configuration diagram of the refrigeration cycle device 1a.

[0047] Figure 6 It is a diagram for explaining the flow of the refrigerant during the heating operation of the refrigeration cycle device 1a.

[0048] Figure 7 It is a diagram for explaining the flow of the refrigerant during the cooling and heating operation of the refrigeration cycle device 1 a. DETAILED DESCRIPTION

[0049] <First embodiment>

[0050] (1) Overall structure

[0051] Figure 1 It is a schematic configuration diagram of the refrigeration cycle device 1 according to the first embodiment.

[0052] The refrigeration cycle device 1 includes a refrigerant circuit 90 and a control unit 100. The refrigerant circuit 90 mainly includes a compressor 10, a switching mechanism 20, a first decompression unit 41, a second decompression unit 42, a first valve 51, a second valve 52, a third valve 53, a fourth valve 54, a first heat exchanger 61, a second heat exchanger 62, an internal heat exchanger 63, an energy-saving heat exchanger 64, a liquid accumulator 80, a liquid refrigerant flow path 71, an injection flow path 72, a first branch flow path 73, and a second branch flow path 74.

[0053] More specifically, the refrigeration cycle device 1 causes the refrigerant circuit 90 to perform a refrigeration cycle to heat or cool water circulating in the water circuit 200 , thereby performing heating or cooling operations for a target space (not shown) using the water.

[0054] (2) Detailed structure

[0055] (2-1) Refrigerant circuit 90

[0056] The refrigerant circuit 90 is filled with a flammable refrigerant, but the present invention is not limited thereto. A flammable refrigerant is a refrigerant that is flammable. Examples of flammable refrigerants include hydrocarbon-based refrigerants, R1234yf, R1234ze, and R32. These refrigerants are classified as highly flammable (A3) by ISO 817, and in this embodiment, R290 (propane).

[0057] (2-1-1) Compressor 10

[0058] The compressor 10 compresses the low-pressure refrigerant in the refrigeration cycle to a high-pressure state. More specifically, the compressor 10 is a two-stage compressor that draws in the low-pressure refrigerant in the refrigeration cycle, compresses it to an intermediate pressure in the refrigeration cycle, and then further compresses the intermediate-pressure refrigerant to a high-pressure state before discharging it.

[0059] The compressor 10 includes a housing 10a, a first compression element 10b, a second compression element 10c, a drive motor 10d, a first suction portion 10e, a second suction portion 10f, and a discharge portion 10g.

[0060] Housing 10a houses first and second compression elements 10b, 10c. These elements are connected to a single drive shaft (not shown). During operation, drive motor 10d rotates first and second compression elements 10b, 10c via the drive shaft. In other words, compressor 10 has a single-shaft, two-stage compression structure. The rotational speed of drive motor 10d is controlled by control unit 100.

[0061] The first suction portion 10e draws low-pressure refrigerant from the refrigerant circuit 90. The second suction portion 10f draws intermediate-pressure refrigerant from the refrigerant circuit 90. The discharge portion 10g discharges high-pressure refrigerant to the refrigerant circuit 90. The second suction portion 10f is an example of a suction portion.

[0062] The second suction portion 10 f includes a check valve (not shown) that allows the refrigerant to flow from the outside to the inside of the casing 10 a and restricts the refrigerant from flowing out from the inside of the casing 10 a to the outside.

[0063] The first compression element 10b compresses the refrigerant drawn into the first suction portion 10e to an intermediate pressure and discharges it to the second compression element 10c. The second compression element 10c compresses both the intermediate-pressure refrigerant discharged from the first compression element 10b and the intermediate-pressure refrigerant drawn into the second suction portion 10f to a high pressure and discharges them to the discharge portion 10g.

[0064] The structure of the compressor 10 is not limited to a uniaxial two-stage compression structure, and the structure of the compressor 10 may be composed of, for example, a compression element driven by another drive motor.

[0065] (2-1-2) Switching mechanism 20

[0066] The switching mechanism 20 switches the direction of refrigerant flow in the refrigerant circuit 90 between two states. The switching mechanism 20 is a four-way switching valve having a first valve port P1, a second valve port P2, a third valve port P3, and a fourth valve port P4.

[0067] The switching mechanism 20 is in the first state ( Figure 1 The state shown by the dotted line) and the second state ( Figure 1 The switching mechanism 20 switches between the states (indicated by the solid line in the middle). In the first state, the switching mechanism 20 connects the first valve port P1 with the second valve port P2, and connects the third valve port P3 with the fourth valve port P4. In the second state, the switching mechanism 20 connects the first valve port P1 with the fourth valve port P4, and connects the second valve port P2 with the third valve port P3. The state of the switching mechanism 20 is controlled by the control unit 100.

[0068] The switching mechanism 20 is not limited to a four-way switching valve, and the switching mechanism 22 may be configured by combining a plurality of electromagnetic valves and refrigerant flow paths, for example.

[0069] (2-1-3) First Heat Exchanger 61 and Second Heat Exchanger 62

[0070] The first heat exchanger 61 exchanges heat between the refrigerant flowing in the refrigerant circuit 90 and the water circulating in the water circuit 200. The first heat exchanger 61 functions as a radiator of the refrigerant in heating operation and as an evaporator of the refrigerant in cooling operation. The first heat exchanger 61 has a refrigerant flow path 61a and a water flow path 61b. Figure 1 Only a portion of the water circuit 200 is shown.

[0071] Refrigerant flow path 61a is provided in refrigerant circuit 90. Water flow path 61b is provided in water circuit 200. The refrigerant flowing in refrigerant flow path 61a and the water flowing in water flow path 61b exchange heat with each other. The water that has exchanged heat with the refrigerant circulates in water circuit 200 to heat or cool the air in the target space.

[0072] Hereinafter, for convenience of description, in cooling operation, the end of the refrigerant flow path 61a through which the refrigerant flows is referred to as a first end 61aa, and the end of the refrigerant flow path 61a through which the refrigerant flows out is referred to as a second end 61ab.

[0073] The first heat exchanger 61 is a plate-type heat exchanger, but is not limited thereto. The capacity of the refrigerant flow path 61a is, for example, approximately 0.4 liters.

[0074] The second heat exchanger 62 exchanges heat between the refrigerant flowing through the refrigerant circuit 90 and the air in the location where the second heat exchanger 62 is installed. The second heat exchanger 62 functions as an evaporator for the refrigerant during heating operation and as a radiator for the refrigerant during cooling operation. The second heat exchanger 62 has a refrigerant flow path (not shown).

[0075] The refrigerant flow path of the second heat exchanger 62 is provided in the refrigerant circuit 90. The refrigerant flowing through the refrigerant flow path of the second heat exchanger 62 exchanges heat with the air in the location where the second heat exchanger 62 is installed.

[0076] For convenience of description, in the heating operation, the end of the refrigerant flow path of the second heat exchanger 62 through which the refrigerant flows is referred to as a first end 62aa, and the end of the refrigerant flow path 61a through which the refrigerant flows out is referred to as a second end 62ab.

[0077] The second heat exchanger 62 is a microchannel heat exchanger, but is not limited thereto. The capacity of the refrigerant flow path of the second heat exchanger 62 is, for example, approximately 2.5 liters, which is larger than the capacity of the refrigerant flow path 61 a of the first heat exchanger 61 .

[0078] Hereinafter, for convenience of description, the first heat exchanger 61 and the second heat exchanger 62 may be collectively referred to as a main heat exchanger 60 .

[0079] (2-1-4) Liquid refrigerant flow path 71

[0080] The liquid refrigerant flow path 71 is a refrigerant flow path that connects the first end 61 aa of the refrigerant flow path 61 a of the first heat exchanger 61 and the first end 62 aa of the refrigerant flow path of the second heat exchanger 62 .

[0081] (2-1-5) First Decompression Unit 41

[0082] The first decompression unit 41 decompresses the refrigerant passing therethrough to a low pressure. The first decompression unit 41 is provided in the liquid refrigerant flow path 71. The opening degree of the first decompression unit 41 is controlled by the control unit 100.

[0083] The first decompression unit 41 is an electric expansion valve, but is not limited thereto.

[0084] (2-1-6) Internal heat exchanger 63

[0085] The internal heat exchanger 63 is a pre-cooling heat exchanger that cools the refrigerant flowing from the main heat exchanger 60, which functions as a radiator, to the main heat exchanger 60, which functions as an evaporator. The internal heat exchanger 63 includes a first heat transfer tube 63a and a second heat transfer tube 63b. The internal heat exchanger 63 exchanges heat between the refrigerant passing through the first heat transfer tube 63a and the refrigerant passing through the second heat transfer tube 63b.

[0086] The first heat transfer tube 63a allows refrigerant to flow from the main heat exchanger 60, which functions as an evaporator, to the first suction port 10e of the compressor 10. One end of the first heat transfer tube 63a is connected to the third valve port P3 of the switching mechanism 20. The other end of the first heat transfer tube 63a is connected to the first suction port 10e of the compressor 10 via the accumulator 80.

[0087] The second heat transfer pipe 63b passes refrigerant flowing from the main heat exchanger 60 functioning as a radiator to the main heat exchanger 60 functioning as an evaporator. Both ends of the second heat transfer pipe 63b are connected to the liquid refrigerant flow path 71 between the first heat exchanger 61 and the first decompression unit 41.

[0088] As will be described in detail later, the refrigerant flows through the first heat transfer tube 63a and the second heat transfer tube 63b of the internal heat exchanger 63 during heating operation (in other words, flows through the internal heat exchanger 63), but does not flow through the second heat transfer tube 63b during cooling operation.

[0089] (2-1-7) First Branch Flow Path 73 and Second Branch Flow Path 74

[0090] The first branch flow path 73 and the second branch flow path 74 are refrigerant flow paths that branch from the liquid refrigerant flow path 71 between the first heat exchanger 61 and the first decompression unit 41 and are connected to the second heat transfer pipe 63b. The first branch flow path 73 branches from the liquid refrigerant flow path 71 at a position closer to the first heat exchanger 61 than the second branch flow path 74 (in other words, farther from the first decompression unit 41).

[0091] One end of the second heat transfer tube 63b is connected to the end of the first branch flow path 73 opposite to the liquid refrigerant flow path 71 . The other end of the second heat transfer tube 63b is connected to the end of the second branch flow path 74 opposite to the liquid refrigerant flow path 71 .

[0092] Hereinafter, for convenience of description, the portion where the first branch flow path 73 branches off from the liquid refrigerant flow path 71 may be referred to as a first branch portion 73a, and the portion where the second branch flow path 74 branches off from the liquid refrigerant flow path 71 may be referred to as a second branch portion 74a.

[0093] (2-1-8) Injection flow path 72

[0094] The injection flow path 72 is a refrigerant flow path that branches off from the liquid refrigerant flow path 71 and is connected to the first suction portion 10 e and the second suction portion 10 f of the compressor 10 .

[0095] In this embodiment, the injection flow path 72 includes a first portion 72a, a second portion 72b, a third portion 72c, and a fourth portion 74d.

[0096] The first portion 72 a is a flow path that branches off from the liquid refrigerant flow path 71 and is shared with the first branched flow path 73 over a predetermined length.

[0097] The second portion 72b is a flow path that allows the refrigerant flowing through the first portion 72a to flow into the first heat transfer tube 64a (described later) of the economizer heat exchanger 64. The second portion 72b is connected to the end of the first portion 72a opposite the branching point from the liquid refrigerant flow path 71. The first heat transfer tube 64a of the economizer heat exchanger 64 is provided midway in the second portion 72b.

[0098] The third portion 73c is a flow path for allowing refrigerant flowing through the first heat transfer tube 64a of the economizer heat exchanger 64 to flow into the first suction port 10e of the compressor 10. The third portion 73c connects the end of the second portion 72b opposite to the first portion 72a to the first suction port 10e of the compressor 10.

[0099] The fourth portion 74c is a flow path for allowing the refrigerant flowing through the first heat transfer tube 64a of the economizer heat exchanger 64 to flow into the second suction portion 10f of the compressor 10. The fourth portion 74c connects the end of the second portion 72b opposite to the first portion 72a to the second suction portion 10f of the compressor 10.

[0100] (2-1-9) Second decompression unit 42

[0101] Second decompression unit 42 decompresses the refrigerant passing through injection flow path 72 to an intermediate pressure. Second decompression unit 42 is provided between the connection portion of second portion 72b of injection flow path 72, which is connected to first portion 72a, and economizer heat exchanger 64. The opening degree of second decompression unit 42 is controlled by control unit 100.

[0102] The second decompression unit 42 is an electric expansion valve, but is not limited thereto.

[0103] (2-1-10) Energy-saving heat exchanger 64

[0104] The economizer heat exchanger 64 exchanges heat between the refrigerant, which has been decompressed by the second decompression unit 42 and passes through the injection flow path 72, and the refrigerant flowing from the main heat exchanger 60, which functions as a radiator, to the main heat exchanger 60, which functions as an evaporator. The economizer heat exchanger 64 includes a first heat transfer tube 64a and a second heat transfer tube 64b. The economizer heat exchanger 64 exchanges heat between the refrigerant passing through the first heat transfer tube 64a and the refrigerant passing through the second heat transfer tube 64b.

[0105] The refrigerant flowing through the injection flow path 72 passes through the first heat transfer pipe 64a. The first heat transfer pipe 64a is provided in the injection flow path 72. One end of the first heat transfer pipe 64a is connected to the second decompression unit 42 via the injection flow path 72. The other end of the first heat transfer pipe 64a is connected to the first suction port 10e and the second suction port 10f of the compressor 10 via the injection flow path 72.

[0106] The refrigerant flowing in the first branched flow path 73 passes through the second heat transfer tube 64b. The second heat transfer tube 64b is provided in the first branched flow path 73. One end of the second heat transfer tube 64b is connected to the first valve 51 via the first branched flow path 73. The other end of the second heat transfer tube 64b is connected to the second heat transfer tube 63b of the internal heat exchanger 63 via the first branched flow path 73.

[0107] As will be described in detail later, the refrigerant passes through the first heat transfer tube 64a and the second heat transfer tube 64b of the economizer heat exchanger 64 (in other words, passes through the economizer heat exchanger 64) during heating operation, but does not pass through the economizer heat exchanger 64 during cooling operation.

[0108] (2-1-11) First valve 51

[0109] The first valve 51 restricts the flow of refrigerant from the liquid refrigerant flow path 71 to the economizer heat exchanger 64 in the first portion 72a of the injection flow path 72. The first valve 51 is an on-off valve that switches between an open state and a closed state. Switching between the open and closed states of the first valve 51 is controlled by the control unit 100.

[0110] The first valve 51 is opened during the heating operation and is closed during the cooling operation.

[0111] (2-1-12) Second valve 52

[0112] The second valve 52 restricts the flow of refrigerant flowing through the injection flow path 72 into the first suction port 10e of the compressor 10 at the third portion 72c of the injection flow path 72. The second valve 52 is an on-off valve that switches between an open state and a closed state. Switching between the open and closed states of the second valve 52 is controlled by the controller 100.

[0113] The second valve 52 is closed during the heating operation and is opened during the cooling operation.

[0114] (2-1-13) Third valve 53

[0115] The third valve 53 restricts the flow of refrigerant from the liquid refrigerant flow path 71 to the second heat transfer tube 63b in the second branch flow path 74. The third valve 53 is a check valve that restricts the flow of refrigerant from the liquid refrigerant flow path 71 to the second heat transfer tube 63b and allows the flow of refrigerant from the second heat transfer tube 63b to the liquid refrigerant flow path 71.

[0116] (2-1-14) Fourth valve 54

[0117] The fourth valve 54 restricts the flow of refrigerant from the first branch portion 73a to the second branch portion 74a in the liquid refrigerant flow path 71. The fourth valve 54 is provided between the first branch portion 73a and the second branch portion 74a in the liquid refrigerant flow path 71. The fourth valve 54 is a check valve that restricts the flow of refrigerant from the first branch portion 73a to the second branch portion 74a and allows the flow of refrigerant from the second branch portion 74a to the first branch portion 73a.

[0118] The third valve 53 is opened during the heating operation and closed during the cooling operation.

[0119] (2-1-15) Liquid reservoir 80

[0120] The accumulator 80 separates the refrigerant flowing out of the first heat transfer pipe 63a and into the first suction port 10e of the compressor 10 into gas refrigerant and liquid refrigerant.

[0121] (2-2) Control Unit 100

[0122] This is a block diagram of the control unit 100. The control unit 100 controls each device in the refrigerant circuit 90 to cause the refrigerant circuit 90 to perform a refrigeration cycle. The control unit 100 is electrically connected to the compressor 10, the switching mechanism 20, the first decompression unit 41, the second decompression unit 42, the first valve 51, and the second valve 52 so as to be able to transmit and receive signals.

[0123] The control unit 30 is implemented as a computer. The control unit 100 includes a control arithmetic device and a storage device (both not shown). The control arithmetic device can be a processor such as a CPU or a GPU. The control arithmetic device reads a program stored in the storage device and performs predetermined arithmetic processing according to the program. Furthermore, the control arithmetic device can write the calculation results to the storage device or read information stored in the storage device according to the program.

[0124] (3) Overall movement

[0125] The control unit 100 controls each device as described below during the heating operation and the cooling operation. Figure 3 It is a diagram for explaining the flow of the refrigerant during the heating operation of the refrigeration cycle device 1 . Figure 4 It is a diagram for explaining the flow of the refrigerant during the cooling operation of the refrigeration cycle device 1 . Figure 3 and Figure 4 A refrigerant flow path through which the refrigerant flows is indicated by a dotted line, and the direction in which the refrigerant flows is indicated by an arrow.

[0126] (3-1) Heating operation

[0127] When the execution of the heating operation is instructed to the refrigeration cycle apparatus 1 , the control unit 100 controls each unit of the refrigerant circuit 90 as follows.

[0128] The control unit 100 starts the operation of the compressor 10 and controls the rotational speed of the drive motor 10d. The switching mechanism 20 is controlled to the first state. The opening of the first decompression unit 41 is controlled. The control unit 100 controls the opening of the first decompression unit 41, for example, so that the subcooling degree of the refrigerant flowing out of the first end 61aa of the first heat exchanger 61 approaches a predetermined target subcooling degree. The opening of the second decompression unit 42 is controlled. The control unit 100 controls the opening of the second decompression unit 42, for example, so that the superheat degree of the refrigerant flowing out of the second decompression unit 42 approaches a predetermined target superheat degree. The first valve 51 is controlled to be in the open state. The second valve 52 is controlled to be in the closed state.

[0129] When the compressor 10 starts operating, low-pressure gas refrigerant in the refrigeration cycle is drawn into the first suction port 10e, and intermediate-pressure gas refrigerant in the refrigeration cycle is drawn into the second suction port 10f. The first compression element 10b compresses the low-pressure refrigerant drawn into the first suction port 10e to an intermediate pressure and discharges it to the second compression element 10c. The second compression element 10c compresses both the intermediate-pressure refrigerant discharged from the first compression element 10b and the intermediate-pressure refrigerant drawn into the second suction port 10f to a high pressure within the refrigeration cycle and discharges it as gas refrigerant to the discharge port 10g.

[0130] The high-pressure gas refrigerant flowing out of the discharge port 10g passes through the switching mechanism 22, sequentially through the first valve port P1 and the second valve port P2, and flows from the second end 61ab into the refrigerant flow path 61a of the first heat exchanger 61. The refrigerant flowing into the first heat exchanger 61 exchanges heat with the water flowing in the water flow path 61b, condensing into high-pressure liquid refrigerant, which then flows out from the first end 61aa. In other words, the first heat exchanger 61 functions as a radiator.

[0131] High-pressure refrigerant flowing out of the first heat exchanger 61 flows through the liquid refrigerant flow path 71. Because the first valve 51 is open and the fourth valve 54 is located downstream of the first branch portion 73a, the refrigerant flowing in the liquid refrigerant flow path 71 flows into the injection flow path 72 at the first branch portion 73a without passing through the fourth valve 54. The refrigerant flowing into the injection flow path 72 passes through the first valve 51 in the first portion 72a and is then divided into the second portion 72b of the injection flow path 72 and the first branch flow path 73.

[0132] The refrigerant flowing into the second portion 72b of the injection flow path 72 is reduced in pressure to an intermediate pressure while passing through the second decompression unit 42. The refrigerant at the intermediate pressure flows into the first heat transfer tube 64a of the economizer heat exchanger 64, exchanges heat with the refrigerant passing through the second heat transfer tube 64b of the economizer heat exchanger 64, and then flows out of the first heat transfer tube 64a.

[0133] Since the second valve 52 is closed, the refrigerant flowing out of the first heat transfer pipe 64a does not flow into the third portion 72c of the injection flow path 72, but flows into the fourth portion 72d of the injection flow path 72. The refrigerant flowing into the fourth portion 72d is sucked into the compressor 10 again through the second suction portion 10f.

[0134] The refrigerant flowing into the first branch flow path 73 flows into the second heat transfer tube 64b of the economizer heat exchanger 64, exchanges heat with the refrigerant passing through the first heat transfer tube 64a of the economizer heat exchanger 64, and flows out of the second heat transfer tube 64b.

[0135] The refrigerant flowing out of the second heat transfer tube 64b passes through the first branch flow path 73 and flows into the second heat transfer tube 63b of the internal heat exchanger 63. The refrigerant flowing into the second heat transfer tube 63b exchanges heat with the refrigerant passing through the first heat transfer tube 63a of the internal heat exchanger 63, and then flows out of the second branch flow path 74. The refrigerant flowing out of the second branch flow path 74 passes through the third valve 53 and flows into the liquid refrigerant flow path 71.

[0136] The refrigerant flowing into the liquid refrigerant flow path 71 is reduced in pressure to a low level when passing through the first decompression unit 41, becoming a gas-liquid two-phase refrigerant. The refrigerant then flows from the first end 62aa into the second heat exchanger 62. The refrigerant flowing into the second heat exchanger 62 exchanges heat with the air in the location where the second heat exchanger 62 is installed, causing it to evaporate and become a low-pressure gas refrigerant. The refrigerant then flows out from the second end 62ab. In other words, the second heat exchanger 62 functions as an evaporator.

[0137] The low-pressure refrigerant flowing out of the second heat exchanger 62 passes through the switching mechanism 22, sequentially through the fourth valve port P4 and the third valve port P3, and flows into the first heat transfer tube 63a of the internal heat exchanger 63. The refrigerant flowing into the first heat transfer tube 63a exchanges heat with the refrigerant passing through the second heat transfer tube 63b of the internal heat exchanger 63, and then flows out of the first heat transfer tube 63a. The refrigerant flowing out of the first heat transfer tube 63a passes through the accumulator 80 and is again drawn into the compressor 10 through the first suction port 10e.

[0138] In this manner, the internal heat exchanger 63 and the economizer heat exchanger 64 are configured so that the refrigerant flows during the heating operation.

[0139] (3-2) Refrigeration operation

[0140] When the execution of the cooling operation is instructed to the refrigeration cycle apparatus 1 , the control unit 100 controls each unit of the refrigerant circuit 90 as follows.

[0141] The controller 100 starts the compressor 10 and controls the rotational speed of the drive motor 10d. The switching mechanism 20 is controlled to the second state. The opening of the first decompression unit 41 is controlled. For example, the controller 100 controls the opening of the first decompression unit 41 so that the superheat of the refrigerant flowing out of the second end 61ab of the first heat exchanger 61 approaches a predetermined target superheat. The second decompression unit 42 is controlled to be fully open or substantially fully open (hereinafter referred to as fully open). The first valve 51 is controlled to be closed. The second valve 52 is controlled to be open.

[0142] When the compressor 10 starts operating, low-pressure gas refrigerant in the refrigeration cycle is drawn into the first suction port 10e. The first compression element 10b compresses the low-pressure refrigerant drawn into the first suction port 10e to an intermediate pressure and discharges it to the second compression element 10c. The second compression element 10c compresses the intermediate-pressure refrigerant discharged from the first compression element 10b to a high pressure in the refrigeration cycle and discharges it as gas refrigerant to the discharge port 10g.

[0143] During cooling operation, a portion of the injection flow path 72 becomes low pressure, as will be described in detail later. Therefore, the check valve of the second suction portion 10f restricts the refrigerant at the intermediate pressure from flowing out of the casing 10a.

[0144] The high-pressure gas refrigerant flowing out of the discharge port 10g passes through the switching mechanism 22, sequentially through the first valve port P1 and the fourth valve port P4, and flows from the second end 62ab into the refrigerant flow path of the second heat exchanger 62. The refrigerant flowing into the second heat exchanger 62 exchanges heat with the air in the location where the second heat exchanger 62 is installed, condensing into high-pressure liquid refrigerant, which then flows out from the first end 62aa. In other words, the second heat exchanger 62 functions as a radiator.

[0145] The high-pressure refrigerant flowing out of the second heat exchanger 62 flows through the liquid refrigerant flow path 71 and is reduced in pressure to a low pressure, becoming a gas-liquid two-phase state, when passing through the first decompression unit 41. Because the third valve 53 is provided in the second branch flow path 74, the refrigerant flowing in the liquid refrigerant flow path 71 does not flow into the second branch flow path 74 but passes through the fourth valve 54.

[0146] Because the first valve 51 is closed, the refrigerant that has passed through the fourth valve 54 does not flow into the first branch flow path 73. Instead, it flows from the first end 61aa into the first heat exchanger 61. The refrigerant that has flowed into the first heat exchanger 61 exchanges heat with the water flowing in the water flow path 61b, causing it to evaporate and become a low-pressure gas refrigerant, which then flows out from the second end 61ab. In other words, the first heat exchanger 61 functions as an evaporator.

[0147] The low-pressure refrigerant flowing out of the first heat exchanger 61 passes through the switching mechanism 22, sequentially through the second valve port P2 and the third valve port P3, and flows into the first heat transfer tube 63a of the internal heat exchanger 63. As described later, during cooling operation, the refrigerant in the second heat transfer tube 63b is recovered by the compressor 10. Therefore, the refrigerant flowing into the first heat transfer tube 63a flows out of the first heat transfer tube 63a without undergoing heat exchange. The refrigerant flowing out of the first heat transfer tube 63a passes through the accumulator 80 and is again drawn into the compressor 10 through the first suction port 10e.

[0148] During cooling operation, since the first valve 51 is closed, refrigerant flowing in the liquid refrigerant flow path 71 does not flow into the injection flow path 72. Furthermore, during cooling operation, the first valve 51 is closed, the second valve 52 is open, and the second decompression unit 42 is fully open. Therefore, as the compressor 10 operates, a portion of the injection flow path 72, the first and second heat transfer tubes 64a and 64b of the economizer heat exchanger 64, the second heat transfer tube 63b of the internal heat exchanger 63, and a portion of the first branch flow path 73 reach low pressure. Specifically, the portion of the injection flow path 72 is the portion between the first valve 51 and the first suction port 10e of the compressor 10. Furthermore, the portion of the first branch flow path 73 is the portion between the first valve 51 and the third valve 53.

[0149] As a result, when switching from heating operation to cooling operation, the refrigerant remaining in a portion of the injection flow path 72, the first heat transfer tube 64a and the second heat transfer tube 64b of the energy-saving heat exchanger 64, the second heat transfer tube 63b of the internal heat exchanger 63, and a portion of the first branch flow path 73 flows into the compressor 10 through the first suction part 10e and is recovered. Figure 4 The refrigerant flow path through which the recovered refrigerant flows is indicated by a dashed line.

[0150] Thus, the internal heat exchanger 63 is configured so that the refrigerant does not flow through the second heat transfer tube 63b during cooling operation. Furthermore, the economizer heat exchanger 64 is configured so that the refrigerant does not flow through the economizer heat exchanger 64 during cooling operation.

[0151] (4) Characteristics

[0152] (4-1)

[0153] The refrigeration cycle device 1 performs heating and cooling operations and includes a compressor 10 , a main heat exchanger 60 (a first heat exchanger 61 and a second heat exchanger 62 ) functioning as a radiator and an evaporator, and an internal heat exchanger 63 .

[0154] The internal heat exchanger 63 includes a first heat transfer tube 63a and a second heat transfer tube 63b. The first heat transfer tube 63a allows refrigerant flowing from the main heat exchanger 60, which functions as an evaporator, to the compressor 10. The second heat transfer tube 63b allows refrigerant flowing from the main heat exchanger 60, which functions as a radiator, to the evaporator. The internal heat exchanger 63 exchanges heat between the refrigerant passing through the first heat transfer tube 63a and the refrigerant passing through the second heat transfer tube 63b. During cooling operation, the refrigerant does not flow through the second heat transfer tube 63b.

[0155] Typically, the amount of refrigerant filled in the refrigerant circuit of a refrigeration cycle device equipped with an internal heat exchanger (refrigerant filling amount) is calculated by adding the capacity of the heat exchanger, which functions as a radiator for the refrigerant, to the capacity of the internal heat exchanger. For example, in the case of refrigeration cycle device 1, the capacities of the first heat exchanger 61 and the second heat exchanger 62, which function as radiators, are compared, and the refrigerant filling amount is calculated by adding the capacity of the second heat exchanger 62, which has the larger capacity, to the capacity of the internal heat exchanger 63.

[0156] During cooling operation, refrigerant does not flow through the second heat transfer tube 63b in the internal heat exchanger 63 of the refrigeration cycle device 1. Therefore, the refrigerant charge in the refrigeration cycle device 1 is calculated based solely on the capacity of the second heat exchanger 62, which functions as a heat sink during cooling operation, without taking into account the capacity of the internal heat exchanger 63. Consequently, the refrigerant charge in the refrigeration cycle device 1 is reduced compared to when the internal heat exchanger 63 is functioning during cooling operation (in other words, when refrigerant is flowing through the second heat transfer tube 63b).

[0157] Furthermore, depending on the climate of the installation location, the refrigeration cycle device may be used more frequently in either heating or cooling operation. For example, in cold regions, the refrigeration cycle device may be used less frequently in cooling operation than in heating operation. As a result, the annual power consumption of a refrigeration cycle device installed in a cold region tends to be less affected by the power consumption during refrigerant operation and more by the power consumption during heating operation. For this reason, the refrigeration cycle device 1 restricts the flow of refrigerant into the internal heat exchanger 63 during cooling operation, thereby limiting its function. However, the impact of such operation on operational efficiency is limited.

[0158] For the reasons described above, the refrigeration cycle apparatus 1 can achieve both a reduction in the refrigerant filling amount and high operating efficiency.

[0159] (4-2)

[0160] The refrigeration cycle device 1 further includes a liquid refrigerant flow path 71 , an injection flow path 72 , a second decompression unit 42 , and an economizer heat exchanger 64 .

[0161] Liquid refrigerant flow path 71 connects main heat exchanger 60, which functions as an evaporator, with main heat exchanger 60, which functions as a radiator. Injection flow path 72 branches from liquid refrigerant flow path 71 and merges with compressor 10. Second decompression unit 42 decompresses the refrigerant passing through injection flow path 72. Economizer heat exchanger 64 exchanges heat between the refrigerant decompressed by second decompression unit 42 and the refrigerant flowing from the radiator to the evaporator.

[0162] Since the present refrigeration cycle device 1 includes the energy-saving heat exchanger 64 , it can be operated at a higher efficiency.

[0163] (4-3)

[0164] During cooling operation, the refrigerant does not flow through the economizer heat exchanger 64 .

[0165] Therefore, the refrigerant charge of refrigeration cycle device 1 is calculated based solely on the capacity of second heat exchanger 62, which functions as a radiator during cooling operation, without taking into account the capacities of internal heat exchanger 63 and economizer heat exchanger 64. Consequently, according to refrigeration cycle device 1, the refrigerant charge is reduced compared to when economizer heat exchanger 64 is functioning during cooling operation. Thus, refrigeration cycle device 1 can achieve both a reduced refrigerant charge and high operational efficiency.

[0166] (4-4)

[0167] During heating operation, the refrigerant flows through the internal heat exchanger 63 and the economizer heat exchanger 64 .

[0168] The refrigeration cycle device 1 operates with higher efficiency because the internal heat exchanger 63 and the economizer heat exchanger 64 function during the heating operation.

[0169] (4-5)

[0170] The refrigeration cycle device 1 further includes a first valve 51 that restricts the flow of refrigerant from the liquid refrigerant flow path 71 to the economizer heat exchanger 64 .

[0171] The first valve 51 restricts the flow of refrigerant from the liquid refrigerant flow path 71 to the economizer heat exchanger 64 during cooling operation.

[0172] (4-6)

[0173] The first valve 51 is a valve that switches between an open state and a closed state.

[0174] (4-7)

[0175] The first valve 51 is in a closed state during cooling operation.

[0176] The first valve 51 can restrict the flow of refrigerant from the liquid refrigerant flow path 71 to the economizer heat exchanger 64 during cooling operation.

[0177] (4-8)

[0178] The refrigeration cycle device 1 further includes a second valve 52 that restricts the flow of the refrigerant flowing through the injection flow path 72 into the compressor 10 .

[0179] The second valve 52 can restrict the flow of refrigerant from the injection flow path 72 to the compressor 10 .

[0180] (4-9)

[0181] The second valve 52 is a valve that switches between an open state and a closed state.

[0182] (4-10)

[0183] The second valve 52 is in an open state during cooling operation.

[0184] By closing the second valve 52, the pressure in a portion of the injection flow path 72, the first and second heat transfer tubes 64a, 64b of the economizer heat exchanger 64, the second heat transfer tube 63b of the internal heat exchanger 63, and the first branch flow path 73 is reduced. As a result, when switching from heating to cooling operation, refrigerant remaining in a portion of the injection flow path 72, the first and second heat transfer tubes 64a, 64b of the economizer heat exchanger 64, the second heat transfer tube 63b of the internal heat exchanger 63, and the first branch flow path 73 flows into the compressor 10 and is recovered. Therefore, according to the refrigeration cycle device 1, during cooling operation, it is possible to prevent refrigerant shortages in the refrigerant circuit 90.

[0185] (4-11)

[0186] The refrigeration cycle device 1 further includes a first branch flow path 73 and a second branch flow path 74 branching from the liquid refrigerant flow path 71 .

[0187] One end of the second heat transfer tube 63 b is connected to the end of the first branch flow path 73 opposite to the liquid refrigerant flow path 71 , and the other end is connected to the end of the second branch flow path 74 opposite to the liquid refrigerant flow path 71 .

[0188] (4-12)

[0189] The third valve 53 is further provided. The third valve 53 restricts the flow of the refrigerant from the liquid refrigerant flow path 71 to the second heat transfer tube 63 b in the second branch flow path 74 .

[0190] The third valve 53 prevents the refrigerant from flowing into the second heat transfer tube 63 b of the internal heat exchanger 63 during cooling operation.

[0191] (4-13)

[0192] The third valve 53 is a check valve.

[0193] (4-14)

[0194] The refrigeration cycle device 1 further includes a fourth valve 54. The fourth valve 54 is a check valve that restricts the flow of refrigerant from the first branch portion 73a, where the first branch flow path 73 branches off from the liquid refrigerant flow path 71, to the second branch portion 74a, where the second branch flow path 74 branches off from the liquid refrigerant flow path 71.

[0195] The fourth valve 54 promotes the flow of the refrigerant flowing out of the radiator into the first branch flow path 73 during the heating operation.

[0196] (4-15)

[0197] The economizer heat exchanger 64 exchanges heat between the refrigerant flowing through the injection flow path 72 and the refrigerant flowing through the first branch flow path 73 .

[0198] During heating operation, the economizer heat exchanger 64 further radiates heat from the refrigerant after the refrigerant has radiated heat in the first heat exchanger 61 functioning as a radiator, thereby supercooling the refrigerant.

[0199] (4-16)

[0200] The refrigerant used in the refrigeration cycle device 1 is a flammable refrigerant (propane).

[0201] According to the refrigeration cycle device 1, the amount of refrigerant filling the refrigerant circuit 90 can be reduced. Therefore, even if a refrigerant leak occurs, the amount of leaked refrigerant can be reduced. Therefore, even when a flammable refrigerant is used, accidents caused by leakage can be reduced.

[0202] (5) Modification

[0203] (5-1)

[0204] The heat source for heat exchange performed by the refrigerant flowing in the refrigerant flow path 61a is not limited to water, and heat exchange may be performed with the air in the target space, for example. In this case, the first heat exchanger 61 is disposed in the target space.

[0205] (5-2)

[0206] The refrigerant filled in the refrigerant circuit 90 is not limited to propane.

[0207] <Second embodiment>

[0208] (1) Overall structure

[0209] Figure 5 This is a schematic structural diagram of a refrigeration cycle device 1a according to a second embodiment. Refrigeration cycle device 1 differs from refrigeration cycle device 1a in the location of first decompression unit 41 and in that refrigerant circuit 90 of refrigeration cycle device 1a further includes fifth valve 55, sixth valve 56, and third branch flow path 75.

[0210] The following description will focus on the differences between the refrigeration cycle apparatus 1 and the refrigeration cycle apparatus 1a. The same or corresponding features between the refrigeration cycle apparatus 1 and the refrigeration cycle apparatus 1a are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

[0211] (2) Detailed structure

[0212] (2-1) First decompression unit 41

[0213] The first decompression unit 41 of the refrigeration cycle device 1a decompresses the refrigerant passing through the second branch flow path 74 to a low pressure. The first decompression unit 41 of the refrigeration cycle device 1a is provided between the second branch portion 74a and the third valve 53 of the second branch flow path 74.

[0214] (2-2) Third branch flow path 75

[0215] The third branch flow path 75 is a refrigerant flow path that branches from the second branch flow path 74 between the first decompression unit 41 and the third valve 53 and is connected to a portion of the liquid refrigerant flow path 71 opposite to the fourth valve 54 across the second branch portion 74 a .

[0216] (2-3) Fifth valve 55

[0217] The fifth valve 55 restricts the flow of refrigerant from the connection portion 75a of the third branched flow path 75 to the second branched portion 74a in the liquid refrigerant flow path 71. The fifth valve 55 is provided between the connection portion 75a and the second branched portion 74a in the liquid refrigerant flow path 71. The fifth valve 55 is a check valve that restricts the flow of refrigerant from the connection portion 75a to the second branched portion 74a and allows the flow of refrigerant from the second branched portion 74a to the connection portion 75a.

[0218] (2-4) Sixth valve 56

[0219] The sixth valve 56 restricts the flow of refrigerant from the second branch flow path 74 to the liquid refrigerant flow path 71 in the third branch flow path 75. The sixth valve 56 is provided in the third branch flow path 75. The sixth valve 56 is a check valve that restricts the flow of refrigerant from the second branch flow path 74 to the liquid refrigerant flow path 71 and allows the flow of refrigerant from the liquid refrigerant flow path 71 to the second branch flow path 74.

[0220] (3) Overall movement

[0221] Figure 6 It is a diagram for explaining the flow of the refrigerant during the heating operation of the refrigeration cycle device 1a. Figure 7 It is a diagram for explaining the flow of the refrigerant during the cooling operation of the refrigeration cycle device 1a. Figure 6 and Figure 7 In FIG. 1 , a refrigerant flow path through which the refrigerant flows is indicated by a dotted line, and a direction in which the refrigerant flows is indicated by an arrow.

[0222] (3-1) Heating operation

[0223] The refrigerant flow during heating operation of the refrigeration cycle device 1a differs from the refrigerant flow during heating operation of the refrigeration cycle device 1 in the refrigerant flow path from the second heat transfer tube 63b of the internal heat exchanger 63 to the second branch flow path 74 until it flows into the second heat exchanger 62. Therefore, only the refrigerant flow path from the refrigerant flowing out of the second branch flow path 74 to the refrigerant flowing into the second heat exchanger 62 will be described here.

[0224] Because the sixth valve 56 is provided in the third branch flow path 75, refrigerant flowing from the second heat transfer tube 63b of the internal heat exchanger 63 into the second branch flow path 74 does not flow into the third branch flow path 75. Refrigerant flowing into the second branch flow path 74 passes through the third valve 53 and the first decompression unit 41 and flows into the liquid refrigerant flow path 71. The refrigerant flowing into the second branch flow path 74 is decompressed to a low pressure when passing through the first decompression unit 41, becoming a gas-liquid two-phase refrigerant. Refrigerant flowing into the liquid refrigerant flow path 71 passes through the fifth valve 55 and flows from the first end 62aa into the second heat exchanger 62.

[0225] (3-2) Refrigeration operation

[0226] The flow of the refrigerant during the cooling operation of the refrigeration cycle device 1a differs from the flow of the refrigerant during the cooling operation of the refrigeration cycle device 1 in the path of the refrigerant flowing out of the second heat exchanger 62 until it passes through the fourth valve 54. Therefore, here, only the path of the refrigerant from flowing out of the second heat exchanger 62 until it passes through the fourth valve 54 is described.

[0227] Since the fifth valve 55 is provided in the liquid refrigerant flow path 71 , the high-pressure refrigerant flowing out of the second heat exchanger 62 flows into the third branch flow path 75 .

[0228] The refrigerant flowing into the third branch flow path 75 passes through the sixth valve 56 and flows into the second branch flow path 74. Because the third valve 53 is installed in the second branch flow path 74, the refrigerant flowing into the second branch flow path 74 does not flow into the second heat transfer tube 63b of the internal heat exchanger 63. The refrigerant flowing into the second branch flow path 74 is reduced in pressure to a low level when passing through the first decompression unit 41, becoming a gas-liquid two-phase state. The refrigerant passing through the first decompression unit 41 flows into the liquid refrigerant flow path 71 and passes through the fourth valve 54.

[0229] (4) Characteristics

[0230] (4-1)

[0231] The refrigeration cycle device 1 a further includes a first decompression unit 41 , a third branch flow path 75 , a fifth valve 55 , and a sixth valve 56 .

[0232] The first decompression unit 41 decompresses the refrigerant between the second branch portion 74a of the second branch flow path 74 and the third valve 53. The third branch flow path 75 branches from the second branch flow path 74 between the first decompression unit 41 and the third valve 53 and is connected to a portion of the liquid refrigerant flow path 71 opposite the fourth valve 54 across the second branch portion 74a. The fifth valve 55 restricts the flow of refrigerant from the connection portion 75a of the third branch flow path 75 to the second branch portion 74a in the liquid refrigerant flow path 71. The sixth valve 56 restricts the flow of refrigerant from the second branch flow path 74 to the liquid refrigerant flow path 71 in the third branch flow path 75.

[0233] The fifth valve 55 and the sixth valve 56 are provided in a refrigerant flow path extending from the upstream side to the downstream side of the first decompression unit 41 via the third branch flow path 75. Therefore, the fifth valve 55 and the sixth valve 56 reliably operate by utilizing the refrigerant pressure difference generated between the upstream side and the downstream side of the first decompression unit 41, thereby suppressing the refrigerant from flowing in an undesired direction.

[0234] While the embodiments of the present disclosure have been described above, it should be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as described in the claims.

[0235] Description of labels

[0236] 1 Refrigeration cycle device

[0237] 10 compressors

[0238] 20 switching mechanism

[0239] 41 First decompression unit

[0240] 42 Second decompression unit

[0241] 51 First Valve

[0242] 52 Second Valve

[0243] 53 third valve

[0244] 54 Fourth Valve

[0245] 55 Fifth Valve

[0246] 56 Sixth Valve

[0247] 61 First heat exchanger (radiator or evaporator)

[0248] 62 Second heat exchanger (radiator or evaporator)

[0249] 63 internal heat exchanger

[0250] 63a first heat transfer tube

[0251] 63b second heat transfer tube

[0252] 64 Energy-saving heat exchanger

[0253] 71 Liquid refrigerant flow path

[0254] 72 injection flow path

[0255] 73 first branch flow path

[0256] 74 Second branch flow path

[0257] 75 third branch flow path

[0258] 90 refrigerant circuit

[0259] Prior art literature

[0260] Patent Literature

[0261] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-21013

Claims

1. A refrigeration cycle device (1) that performs heating operation and cooling operation, wherein: The refrigeration cycle device (1) includes a compressor (10), a radiator (61, 62), an internal heat exchanger (63), and an evaporator (61, 62). The internal heat exchanger has: a first heat transfer pipe (63a) through which the refrigerant flowing from the evaporator to the compressor passes; and a second heat transfer tube (63b) for the refrigerant flowing from the radiator to the evaporator to pass through; The internal heat exchanger exchanges heat between the refrigerant passing through the first heat transfer tube and the refrigerant passing through the second heat transfer tube. During the cooling operation, the refrigerant does not flow through the second heat transfer tube.

2. The refrigeration cycle device according to claim 1, wherein The refrigeration cycle device further comprises: a liquid refrigerant flow path (71) connecting the evaporator and the radiator; an injection flow path (72) branching from the liquid refrigerant flow path and merging with the compressor; a second decompression unit (42) for decompressing the refrigerant passing through the injection flow path; as well as An energy-saving heat exchanger (64) performs heat exchange between the refrigerant decompressed by the second decompression unit and the refrigerant flowing from the radiator to the evaporator.

3. The refrigeration cycle device according to claim 2, wherein: During the cooling operation, the refrigerant does not flow through the economizer heat exchanger.

4. The refrigeration cycle device according to claim 3, wherein: During the heating operation, the refrigerant flows through the internal heat exchanger and the energy-saving heat exchanger.

5. The refrigeration cycle device according to claim 2, wherein The refrigeration cycle device further includes a first valve (51) that restricts the flow of the refrigerant from the liquid refrigerant flow path to the energy-saving heat exchanger.

6. The refrigeration cycle device according to claim 5, wherein The first valve is a valve that switches between an open state and a closed state.

7. The refrigeration cycle device according to claim 6, wherein: The first valve is in a closed state during the cooling operation.

8. The refrigeration cycle device according to claim 2, wherein: The refrigeration cycle device further includes a second valve (52) that restricts the flow of the refrigerant flowing in the injection flow path into the compressor.

9. The refrigeration cycle device according to claim 7, wherein: The second valve is a valve that switches between an open state and a closed state.

10. The refrigeration cycle device according to claim 8, wherein The second valve is in an open state during the cooling operation.

11. The refrigeration cycle device according to claim 8, wherein The refrigeration cycle device further includes a first branch flow path (73) and a second branch flow path (74) branching from the liquid refrigerant flow path. One end of the second heat transfer tube is connected to the end of the first branch flow path opposite to the liquid refrigerant flow path, and the other end is connected to the end of the second branch flow path opposite to the liquid refrigerant flow path.

12. The refrigeration cycle device according to claim 11, wherein The refrigeration cycle device further includes a third valve (53) that restricts the flow of the refrigerant from the liquid refrigerant flow path to the second heat transfer tube in the second branch flow path.

13. The refrigeration cycle device according to claim 12, wherein: The third valve is a check valve.

14. The refrigeration cycle device according to claim 12, wherein: The refrigeration cycle device also includes a fourth valve (54), which is a check valve that restricts the flow of the refrigerant from the first branch portion (73a) to the second branch portion (74a), the first branch portion (73a) being the portion where the first branch flow path branches off from the liquid refrigerant flow path, and the second branch portion (74a) being the portion where the second branch flow path branches off from the liquid refrigerant flow path.

15. The refrigeration cycle device according to claim 14, wherein The economizer heat exchanger exchanges heat between the refrigerant flowing through the injection flow path and the refrigerant flowing through the first branch flow path.

16. The refrigeration cycle device according to claim 14, wherein The refrigeration cycle device further comprises: a first decompression unit (41) for decompressing the refrigerant between the second branch portion of the second branch flow path and the third valve; a third branch flow path (75) branching from the second branch flow path between the first decompression unit and the third valve, and connected to a portion of the liquid refrigerant flow path on the opposite side of the fourth valve across the second branch portion; a fifth valve (55) that restricts the flow of the refrigerant from the connecting portion (75a) of the third branch flow path to the second branch portion in the liquid refrigerant flow path; as well as A sixth valve (56) restricts the flow of the refrigerant from the second branch flow path to the liquid refrigerant flow path in the third branch flow path.

17. The refrigeration cycle device according to any one of claims 1 to 16, wherein: The refrigerant is flammable.

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