Refrigeration cycle device

Abstract

A control substrate (6) provided in a refrigeration cycle device (1) is provided at a position above refrigerant passages (31, 32) in a first heat exchanger (6). In the first heat exchanger (6), refrigerant flowing into the refrigerant passages (31, 32) flows from the lowermost path to the uppermost path in a plurality of stages of paths (37a-37d, 38a-38d). The refrigerant passages (31, 32) are divided into two columns, consisting of a first-column refrigerant passage (31) and a second-column refrigerant passage (32). The first-column refrigerant passage (31) and the second-column refrigerant passage (32) are connected by connection pipes (12, 13, 14). An inflow passage (11) is provided to the lowermost path of the plurality of stages of paths (37a-37d) in the first column refrigerant passage (31). An outflow passage (15) is provided to the uppermost path of the plurality of stages of paths (38a-38d) in the second-column refrigerant passage (32).

Description

Refrigeration cycle equipment

[0001] The present disclosure relates to a refrigeration cycle device.

[0002] The refrigeration cycle device is equipped with a control board on which electronic components for controlling the operation of the refrigeration cycle device are mounted. The control board is equipped with various electronic components, including a control microcomputer and electronic components constituting an inverter circuit, for example. The microcomputer and the electronic components constituting the inverter circuit generate a relatively large amount of heat.

[0003] A refrigeration cycle apparatus includes an outdoor unit and an indoor unit, and a control board may be housed in both the outdoor unit and the indoor unit. In a refrigeration cycle apparatus installed in an area with a relatively high outdoor temperature, there is a concern that the heat generated by the temperature rise of the control board housed in the outdoor unit, in addition to the heat of the outdoor temperature, may adversely affect the heat exchange between the refrigerant and the air in the control board housed in the outdoor unit. To avoid such adverse effects, Patent Document 1 proposes a method of dissipating the heat generated from the control board by the refrigerant circulating within the refrigeration cycle apparatus.

[0004] Japanese Patent Application Laid-Open No. 2006-170469

[0005] However, conventional refrigeration cycle devices have the following problem: In a configuration in which heat generated by a control board is dissipated by a refrigerant, the refrigerant receives heat from the control board, so the temperature of the refrigerant sent to the indoor unit tends to rise during cooling operation. Therefore, in such a configuration, the desired heat exchange between the refrigerant and air cannot be achieved in the heat exchanger, and heat exchange capacity may be reduced.

[0006] Furthermore, if the temperature of the control board becomes excessively high due to high outside air temperatures, etc., the heat may cause malfunctions in the control performed by the control board, or protective control may be executed to prevent such malfunctions, which may result in a decrease in the heat exchange capacity of the heat exchanger.

[0007] The present disclosure has been made to solve such problems, and its purpose is to provide a refrigeration cycle device that can suppress the temperature rise of the control board and the decrease in the heat exchange capacity of the heat exchanger.

[0008] The refrigeration cycle apparatus according to the present disclosure includes a refrigerant circuit including a compressor, a first heat exchanger, an expansion valve, and a second heat exchanger, through which a refrigerant circulates, and a control board. The first heat exchanger includes a refrigerant path into which refrigerant discharged from the compressor flows, and heat is exchanged between the refrigerant and a cooling medium in the refrigerant path. The control board is provided in the first heat exchanger at a position above the refrigerant path. The refrigerant path of the first heat exchanger includes multiple paths arranged vertically. The first heat exchanger further includes an inlet channel for allowing the refrigerant to flow from a lowest path of the multiple paths into the refrigerant path and an outlet channel for allowing the refrigerant to flow from an uppermost path of the multiple paths to the outside of the refrigerant path. The refrigerant flowing from the inlet channel into the refrigerant path flows through the multiple paths from the lowest path to the uppermost path. The first heat exchanger has a refrigerant path divided into two rows, a first row refrigerant path and a second row refrigerant path, the first row refrigerant path and the second row refrigerant path being connected by a connecting pipe, an inlet path being provided in the lowest row of the multiple stages of paths in the first row refrigerant path, and an outlet path being provided in the highest row of the multiple stages of paths in the second row refrigerant path.

[0009] In the refrigeration cycle apparatus according to the present disclosure, the control board is disposed in a position above the refrigerant path in the first heat exchanger. In the first heat exchanger, the refrigerant path into which the refrigerant discharged from the compressor flows is configured such that the refrigerant flows in through the lowest path of a plurality of paths and flows out through the highest path of the plurality of paths. Thus, the high-temperature refrigerant discharged from the compressor flows into the refrigerant path of the first heat exchanger through the lowest path farthest from the control board, exchanges heat with a cooling medium, and then flows out through the highest path closest to the control board. Therefore, the control board is prevented from receiving heat from the high-temperature refrigerant discharged from the compressor. This configuration prevents the refrigeration cycle apparatus from experiencing a temperature rise in the control board and a decrease in the heat exchange capacity of the first heat exchanger. Furthermore, in the first heat exchanger, the refrigerant path is divided into two rows, a first row refrigerant path and a second row refrigerant path, and an inlet path is provided in the lowest row of the multiple paths in the first row refrigerant path, and an outlet path is provided in the highest row of the multiple paths in the second row refrigerant path.This improves the heat exchange capacity of the first heat exchanger compared to when the refrigerant path is a single row, thereby suppressing a decrease in the heat exchange capacity of the first heat exchanger.

[0010] 1 is a diagram illustrating an example of the configuration of a refrigeration cycle apparatus according to embodiment 1. FIG. 1 is a first perspective view illustrating the structure of a first heat exchanger. FIG. 2 is a second perspective view illustrating the structure of the first heat exchanger. FIG. 3 is a side view illustrating the structure of the first heat exchanger. FIG. 4 is a cross-sectional view illustrating the structure of a refrigerant piping. FIG. 5 is a diagram illustrating an example of a specific flow of refrigerant in the first heat exchanger. FIG. 6 is a block diagram illustrating an example of a control configuration of a refrigeration cycle apparatus according to embodiment 1. FIG. 7 is a flowchart illustrating first liquid pooling prevention control according to embodiment 1. FIG. 8 is a ph diagram illustrating an example of a state change of the refrigeration cycle due to refrigerant injection. FIG. 9 is a diagram illustrating an example of a configuration of a refrigeration cycle apparatus according to embodiment 2. FIG. 10 is a perspective view of a first heat exchanger illustrating an example of an arrangement of temperature sensors according to embodiment 2. FIG. 11 is a block diagram illustrating an example of a control configuration of a refrigeration cycle apparatus according to embodiment 2. FIG. 12 is a flowchart illustrating second liquid pooling prevention control according to embodiment 2.

[0011] Embodiment 1 [Example of Overall Configuration of Refrigeration Cycle Apparatus 1] Fig. 1 is a diagram showing an example of the configuration of a refrigeration cycle apparatus 1 according to embodiment 1. The refrigeration cycle apparatus 1 includes an outdoor unit 2 and an indoor unit 3. Fig. 1 shows the state of the refrigerant circuit of the refrigeration cycle apparatus 1 during cooling operation and heating operation.

[0012] The outdoor unit 2 includes a compressor 4, a flow path switching device 5, a first heat exchanger 6, an expansion valve 7, a flow rate control valve 9, a first fan 60, and a control board 10. The indoor unit 3 includes a second heat exchanger 8 and a second fan 80.

[0013] In the outdoor unit 2 and the outdoor unit 3, a refrigerant circuit 50 in which a refrigerant circulates is configured by the compressor 4, the flow path switching device 5, the first heat exchanger 6, the expansion valve 7, the flow control valve 9, and the second heat exchanger 8. In the refrigerant circuit 50, the compressor 4, the first heat exchanger 6, the expansion valve 7, and the second heat exchanger 8 configure a basic refrigeration cycle.

[0014] The control board 10 is provided near the first heat exchanger 6. The control board 10 is provided with a control device 100 as shown in Fig. 7. The control board 10 is provided with a heat sink 20 that absorbs and dissipates heat from the control board 10. The heat sink 20 is a member with a heat dissipation structure that is provided with a plurality of heat dissipation fins.

[0015] The first heat exchanger 6 is a heat exchanger that exchanges heat between outdoor air and the refrigerant. The first heat exchanger 6 functions as a refrigerant condenser during cooling operation and as a refrigerant evaporator during heating operation. The first fan 60 has a function of drawing in outdoor air and discharging the air that has exchanged heat with the refrigerant through the first heat exchanger 6 to the outside.

[0016] The second heat exchanger 8 is a heat exchanger that exchanges heat between the indoor air and the refrigerant. The second heat exchanger 8 functions as a refrigerant evaporator during cooling operation and as a refrigerant condenser during heating operation. The second fan 80 has a function of drawing in indoor air and discharging the air that has exchanged heat with the refrigerant by the second heat exchanger 8 into the room.

[0017] A compressor 4 for compressing the refrigerant is provided in one of the refrigerant flow paths between the first heat exchanger 6 and the second heat exchanger 8. The compressor 4 is driven by a motor. The operating frequency of the compressor 4 can be controlled by inverter control.

[0018] An expansion valve 7 is provided in the other refrigerant flow path between the first heat exchanger 6 and the second heat exchanger 8. The expansion valve 7 has the function of decompressing and expanding the refrigerant, and is configured, for example, as an electronic expansion valve with an adjustable flow rate. The expansion valve 7 can adjust the flow rate of the refrigerant in the refrigerant flow path both during cooling operation and heating operation, and is used to decompress and expand the refrigerant.

[0019] The refrigerant flow path on the expansion valve 7 side of the first heat exchanger 6 branches into an expansion valve flow path 70 as a first flow path and an injection flow path 90 as a second flow path. The expansion valve flow path 70 is provided between the outflow path 15 of the first heat exchanger 6 and the expansion valve 7, and supplies refrigerant to the expansion valve 7 during cooling operation. The injection flow path 90 is provided between the outflow path 15 of the first heat exchanger 6 and an intermediate pressure port 41 of the compressor 4, and supplies refrigerant to the intermediate pressure port 41 of the compressor 4 during cooling operation. The intermediate pressure port 41 is a port configured to supply refrigerant to an intermediate pressure chamber (not shown) of the compressor 4.

[0020] The injection flow path 90 is provided with a flow rate control valve 9 that controls the flow rate of the refrigerant passing through the injection flow path 90. By opening and closing the flow rate control valve 9, the amount of refrigerant supplied to the intermediate pressure chamber of the compressor 4 via the injection flow path 90 is controlled.

[0021] The refrigerant flow path on the discharge side of the compressor 4 is connected to either the first heat exchanger 6 or the second heat exchanger 8 via a flow path switching device 5. The flow path switching device 5 switches the flow path of the refrigerant, and is configured by, for example, a four-way valve.

[0022] During cooling operation, the flow path switching device 5 switches the refrigerant flow path so that the flow path on the discharge side of the compressor 4 is connected to the first heat exchanger 6, as shown by a third flow path 51 in solid line. During heating operation, the flow path switching device 5 switches the refrigerant flow path so that the flow path on the discharge side of the compressor 4 is connected to the second heat exchanger 8, as shown by a fourth flow path 52 in dashed line.

[0023] The outdoor unit 2 is provided with, for example, a suction pressure sensor 71 , a suction temperature sensor 72 , a discharge pressure sensor 73 , a discharge temperature sensor 74 , a frequency sensor 75 , and a heat sink temperature sensor 76 .

[0024] The suction pressure sensor 71 is provided in the piping on the suction side of the compressor 4 and detects the suction pressure of the compressor 4. The suction temperature sensor 72 is provided in the piping on the suction side of the compressor 4 and detects the suction temperature of the compressor 4. The discharge pressure sensor 73 is provided in the piping on the discharge side of the compressor 4 and detects the discharge pressure of the compressor 4. The discharge temperature sensor 74 is provided in the piping on the discharge side of the compressor 4 and detects the discharge temperature of the compressor 4. The frequency sensor 75 is provided in the compressor 4 and detects the operating frequency of the compressor 4. The heat sink temperature sensor 76 is provided in the heat sink 20 and detects the temperature of the heat sink 20.

[0025] [Example of Operation of Refrigeration Cycle Apparatus 1] In FIG. 1, the direction in which the refrigerant flows during cooling is indicated by a solid arrow, and the direction in which the refrigerant flows during heating is indicated by a dashed arrow.

[0026] As an example of operation of the refrigeration cycle apparatus 1, first, an example of operation during cooling operation of the refrigeration cycle apparatus 1 will be described. High-temperature, high-pressure gas refrigerant compressed and discharged by the compressor 4 flows through the flow path switching device 5 into the first heat exchanger 6. The high-temperature, high-pressure refrigerant that flows into the first heat exchanger exchanges heat with outdoor air, etc., and condenses to become high-pressure liquid refrigerant. The high-pressure liquid refrigerant that flows out of the first heat exchanger 6 after heat exchange in the first heat exchanger 6 flows into the expansion valve 7, where it expands and is reduced in pressure to become a low-temperature, low-pressure two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant that flows out of the expansion valve 7 flows into the second heat exchanger 8. The two-phase gas-liquid refrigerant that flows into the second heat exchanger 8 exchanges heat with indoor air, etc., and evaporates to become a low-temperature, low-pressure gas refrigerant. The gas refrigerant that flows out of the second heat exchanger 8 after heat exchange in the second heat exchanger 8 flows through the flow path switching device 5 and is drawn into the compressor 4, where it is compressed again.

[0027] During cooling operation, the control device 100 controls the opening and closing of the flow control valve 9 depending on the temperature of the heat sink 20 detected by the heat sink temperature sensor 76, and a portion of the refrigerant flowing out of the first heat exchanger 6 may be injected into the compressor 4 via the injection flow path 90.

[0028] Next, an example of the operation of the refrigeration cycle apparatus 1 during heating operation will be described. During heating operation, high-temperature, high-pressure gas refrigerant compressed and discharged by the compressor 4 flows through the flow path switching device 5 into the second heat exchanger 8. The high-temperature, high-pressure refrigerant that flows into the second heat exchanger 8 exchanges heat with, for example, indoor air and condenses to become high-pressure liquid refrigerant. The high-pressure liquid refrigerant that flows out of the second heat exchanger 8 after heat exchange in the second heat exchanger 8 flows into the expansion valve 7, where it expands and is decompressed to become a low-temperature, low-pressure two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant that flows out of the expansion valve 7 flows into the first heat exchanger 6. The two-phase gas-liquid refrigerant that flows into the first heat exchanger 6 exchanges heat with, for example, outdoor air and evaporates to become a low-temperature, low-pressure gas refrigerant. The gas refrigerant that flows out of the first heat exchanger 6 after heat exchange in the first heat exchanger 6 is drawn into the compressor 4 via the flow path switching device 5 and compressed again.

[0029] [Configuration example of first heat exchanger 6] Fig. 2 is a first perspective view showing the structure of the first heat exchanger 6. Fig. 3 is a second perspective view showing the structure of the first heat exchanger 6. Fig. 4 is a side view showing the structure of the first heat exchanger 6. Fig. 5 is a cross-sectional view showing the structure of the refrigerant pipe 39.

[0030] 2 and 3, the first heat exchanger 6 includes a first row refrigerant passage 31 and a second row refrigerant passage 32. In FIG. 3, for convenience of explaining the structure, the first row refrigerant passage 31 and the second row refrigerant passage 32 are shown intentionally separated from each other.

[0031] 2 and 3 , the first and second row refrigerant paths 31 and 32 are formed by dividing the refrigerant path in the first heat exchanger 6 into two rows. The first and second row refrigerant paths 31 and 32 are arranged such that, when the refrigeration cycle apparatus 1 is operating, the first row refrigerant path 31 is located on the downwind side and the second row refrigerant path 32 is located on the upwind side of the air flow indicated by the white arrows in the drawings. The first and second row refrigerant paths 31 and 32 are connected by a plurality of connecting pipes 12, 13, and 14.

[0032] 2 and 3 , the first row refrigerant path 31 is provided with a first header pipe 33 at one end in the width direction and a second header pipe 34 at the other end in the width direction. The second row refrigerant path 32 is provided with a third header pipe 35 at one end in the width direction and a fourth header pipe 36 at the other end in the width direction.

[0033] 2 and 3 , in the first row refrigerant passage 31, a first refrigerant path section 37 made up of a plurality of refrigerant pipes is provided between the first header pipe 33 and the second header pipe 34. In the second row refrigerant passage 32, a second refrigerant path section 38 made up of a plurality of refrigerant pipes is provided between the third header pipe 35 and the fourth header pipe 36. In the first heat exchanger 6, heat exchange between the outdoor air and the refrigerant mainly occurs in the first refrigerant path section 37 and the second refrigerant path section 38.

[0034] The first refrigerant path section 37 and the second refrigerant path section 38 use refrigerant piping 39 as shown in FIG. 5 . The refrigerant piping 39 is a flattened tube. In the refrigerant piping 39, the interior of a flattened oval tube 390 is divided into multiple sections, thereby providing multiple flow paths 391 through which the refrigerant flows inside the tube 390. The refrigerant piping 39 made of a flattened tube has a higher heat exchange efficiency than tubes of other shapes due to a larger contact area between the heat transfer surface and the refrigerant. With this configuration, the first heat exchanger 6 can achieve a higher heat exchange efficiency than when other types of heat exchangers are used.

[0035] 4A and 4B , in the first row refrigerant path 31, one end of each refrigerant pipe 39 is located in the first header pipe 33, and the other end of each refrigerant pipe 39 is located in the second header pipe 34. As a result, the first header pipe 33 and the second header pipe 34 are connected by the flow paths 391 of each refrigerant pipe 39, allowing refrigerant to flow between them. Similarly, in the second row refrigerant path 32, one end of each refrigerant pipe 39 is located in the third header pipe 35, and the other end of each refrigerant pipe 39 is located in the fourth header pipe 36. As a result, the third header pipe 35 and the fourth header pipe 36 are connected by the flow paths 391 of each refrigerant pipe 39, allowing refrigerant to flow between them.

[0036] As shown in Fig. 4(A), in the first header piping 33, headers 33a, 33b, 33c, and 33d are formed as spaces separated by baffles 61, 63, and 64 that regulate the flow of the refrigerant. As shown in Fig. 4(A), in the second header piping 34, headers 34a and 34b are formed as spaces separated by a baffle 62 that regulates the flow of the refrigerant.

[0037] As shown in Fig. 4(B), in the third header piping 35, headers 35a, 35b, 35c, and 35d are formed, which are spaces partitioned by baffles 65, 67, and 68 that regulate the flow of the refrigerant. As shown in Fig. 4(B), in the fourth header piping 36, headers 36a and 36b are formed, which are spaces partitioned by a baffle 66 that regulates the flow of the refrigerant.

[0038] 2 to 4, the header 33a is provided with an inlet passage 11 into which the refrigerant discharged from the compressor 4 flows during cooling operation. During heating operation, the inlet passage 11 functions as an outlet passage through which the refrigerant flows from the first heat exchanger 6 toward the compressor 4.

[0039] 2 to 4, the header 33b and the header 35a are connected by the connection pipe 12. The header 33c and the header 35b are connected by the connection pipe 13. The header 33d and the header 35c are connected by the connection pipe 14.

[0040] 2 to 4, the header 35d is provided with an outflow path 15 through which the refrigerant flows out of the first heat exchanger 6 during cooling operation. The outflow path 15 functions as an inflow path through which the refrigerant flowing out of the expansion valve 7 flows in during heating operation.

[0041] 3, the first refrigerant path section 37 includes a plurality of vertically connected refrigerant paths 37a, 37b, 37c, and 37d. In the first refrigerant path section 37, a path 37b is provided above the lowest refrigerant path 37a, a path 37c is provided above the path 37b, and an uppermost path 37d is provided above the path 37c.

[0042] 3, the second refrigerant path section 38 includes multiple refrigerant paths 38a, 38b, 38c, and 38d arranged in a vertical direction. In the second refrigerant path section 38, a path 38b is provided above the lowest refrigerant path 38a, a path 38c is provided above the path 38b, and an uppermost path 38d is provided above the path 38c.

[0043] 3, refrigerant path 37a is provided between header 33a and the lower side of header 34a. Refrigerant path 37b is provided between the upper side of header 34a and header 33b. Refrigerant path 37c is provided between header 33c and the lower side of header 34b. Refrigerant path 37d is provided between the upper side of header 34b and header 33d.

[0044] 3, refrigerant path 38a is provided between header 35a and the lower side of header 36a. Refrigerant path 38b is provided between the upper side of header 36a and header 35b. Refrigerant path 38c is provided between header 35c and the lower side of header 36b. Refrigerant path 38d is provided between the upper side of header 36b and header 35d.

[0045] In the refrigeration cycle apparatus 1, the first heat exchanger 6 functions as a condenser during cooling operation. During cooling operation, as shown by solid arrows in Fig. 3 , in the first heat exchanger 6, the refrigerant flowing in from the inlet path 11 flows through the header 33a, the refrigerant path 37a, the header 34a, the refrigerant path 37b, the header 33b, the connecting pipe 12, the header 35a, the refrigerant path 38a, the header 36a, the refrigerant path 38b, the header 35b, the connecting pipe 13, the header 33c, the refrigerant path 37c, the header 34b, the refrigerant path 37d, the header 33d, the connecting pipe 14, the header 35c, the refrigerant path 38c, the header 36c, the refrigerant path 38d, and the header 35d, and then flows out from the outlet path 15.

[0046] According to the refrigeration cycle apparatus 1 described above, the control board 10 is provided at a position higher than the refrigerant paths (first and second row refrigerant paths 31 and 32) in the first heat exchanger 6. In the first heat exchanger 6, in the refrigerant paths (first and second row refrigerant paths 31 and 32) into which the refrigerant discharged from the compressor 4 flows, the refrigerant flows in from the lowest path (refrigerant path 37a) of the multiple paths (refrigerant paths 37a to 37d, refrigerant paths 38a to 38d) and flows out from the highest path (refrigerant path 38d) of the multiple paths (refrigerant paths 37a to 37d, refrigerant paths 38a to 38d).

[0047] As a result, the high-temperature refrigerant discharged from the compressor 4 flows into the refrigerant paths (first row refrigerant path 31 and second row refrigerant path 32) of the first heat exchanger 6 from the lowest path (refrigerant path 37a) farthest from the control board 10, exchanges heat with the cooling medium, and then flows out from the highest path (refrigerant path 38d) closest to the control board 10 in a lowered temperature state.

[0048] Therefore, the control board 10 is prevented from receiving heat from the high-temperature refrigerant discharged from the compressor 4. As a result, in the refrigeration cycle apparatus 1, a temperature rise in the control board 10 can be suppressed and a decrease in the heat exchange capacity of the first heat exchanger can be suppressed. Furthermore, in the first heat exchanger 6, the refrigerant paths (first-row refrigerant path 31 and second-row refrigerant path 32) are configured in two rows, the first-row refrigerant path 31 and the second-row refrigerant path 32. The inlet path 11 is provided in the lowest path (refrigerant path 37a) of the multiple paths (refrigerant paths 37a to 37d) in the first-row refrigerant path 31, and the outlet path 15 is provided in the highest path (refrigerant path 38d) of the multiple paths (refrigerant paths 38a to 38d) in the second-row refrigerant path 32. This improves the heat exchange capacity of the first heat exchanger 6 compared to when the refrigerant paths are in a single row, thereby suppressing a decrease in the heat exchange capacity of the first heat exchanger 6.

[0049] Furthermore, with the configuration described above, heat dissipation by the heat sink 20 can be promoted.

[0050] In the refrigeration cycle apparatus 1, the first heat exchanger 6 functions as an evaporator during heating operation. During heating operation, the refrigerant flows in the opposite direction to the direction indicated by the solid arrow in Fig. 3. Specifically, in the first heat exchanger 6, the refrigerant flowing in from the outflow path 15 flows through the header 35d, the header 36c, the refrigerant path 38c, the header 35c, the connecting pipe 14, the header 33d, the refrigerant path 37d, the header 34b, the refrigerant path 37c, the header 33c, the connecting pipe 13, the header 35b, the refrigerant path 38b, the header 36a, the refrigerant path 38a, the header 35a, the connecting pipe 12, the header 33b, the refrigerant path 37b, the header 34a, the refrigerant path 37a, and the header 33a, and then flows out from the inflow path 11.

[0051] 6A and 6B are diagrams showing an example of a specific flow of refrigerant in the first heat exchanger 6. In Fig. 6A, the flow of refrigerant in the first row refrigerant path 31 during cooling operation is indicated by solid arrows, and in Fig. 6B, the flow of refrigerant in the second row refrigerant path 32 during cooling operation is indicated by solid arrows. In Fig. 6, the refrigerant pipe 39 is omitted for simplicity of explanation.

[0052] Specific refrigerant flow in the first heat exchanger 6 during cooling operation will be described below with reference to Figures 3, 4, and 6. High-temperature, high-pressure refrigerant (gas refrigerant) discharged from the compressor 4 flows from the inlet passage 11 through the header 33a into the refrigerant path 37a. The refrigerant that has flowed through the refrigerant path 37a passes through the header 34a and into the refrigerant path 37b. The refrigerant that has flowed through the refrigerant path 37b passes through the header 33b and flows into the connecting pipe 12.

[0053] The refrigerant that has flowed through the connecting pipe 12 passes through the header 35a and flows into the refrigerant path 38a. The refrigerant that has flowed through the refrigerant path 38a passes through the header 36a and flows into the refrigerant path 38b. The refrigerant that has flowed through the refrigerant path 38b passes through the header 35b and flows into the connecting pipe 13.

[0054] The refrigerant that has flowed through the connecting pipe 13 passes through the header 33c and flows into the refrigerant path 37c. The refrigerant that has flowed through the refrigerant path 37c passes through the header 34b and flows into the refrigerant path 37d. The refrigerant that has flowed through the refrigerant path 37d passes through the header 33d and flows into the connecting pipe 14.

[0055] The refrigerant that has flowed through the connecting pipe 14 passes through the header 35c and flows into the refrigerant path 38c. The refrigerant that has flowed through the refrigerant path 38c passes through the header 36b and flows into the refrigerant path 38d. The refrigerant that has flowed through the refrigerant path 38d passes through the header 35d and flows out of the outflow path 15, and is sent out toward the expansion valve 7 and the flow control valve 9.

[0056] Each of the pipes constituting the first header pipe 33, the pipes constituting the second header pipe 34, the pipes constituting the third header pipe 35, and the pipes constituting the fourth header pipe 36 is set so that the speed (flow velocity) of the refrigerant flowing through the pipes is equal to or greater than the zero penetration speed, so that the refrigerant oil can be pushed upward in the direction of gravity.

[0057] 4, in the first refrigerant path section 37, the number of refrigerant pipes 39 constituting the refrigerant path in each of the multiple refrigerant paths 37a, 37b, 37c, and 37d varies, with the upper paths having fewer refrigerant pipes 39. Therefore, in the first refrigerant path section 37, the lowest refrigerant path 37a has the greatest number of refrigerant pipes 39, and the highest refrigerant path 37d has the least number of refrigerant pipes 39.

[0058] 4, in the second refrigerant path section 38, the number of refrigerant pipes 39 constituting the refrigerant path in each of the multiple stages of refrigerant paths 38a, 38b, 38c, and 38d varies, with the upper stages having fewer refrigerant pipes 39. Therefore, in the second refrigerant path section 38, the lowest stage refrigerant path 38a has the greatest number of refrigerant pipes 39, and the highest stage refrigerant path 38d has the least number of refrigerant pipes 39.

[0059] In the first heat exchanger 6, the number of refrigerant pipes 39 in the refrigerant path is set so that the number of refrigerant pipes 39 in the refrigerant path decreases from upstream to downstream of the refrigerant flow during cooling operation. This allows the refrigerant, which condenses from a high-temperature, high-pressure gas phase to a lower-temperature liquid phase, to flow efficiently in the first heat exchanger 6.

[0060] [Example of Control Configuration of First Embodiment] Next, a description will be given of an example of a control configuration of the refrigeration cycle apparatus 1. Fig. 7 is a block diagram showing an example of a control configuration of the refrigeration cycle apparatus 1 according to the first embodiment.

[0061] The control device 100 is configured to include a CPU (Central Processing Unit) 101, memory 102 (ROM (Read Only Memory) and RAM (Random Access Memory)), an input / output buffer (not shown) for inputting and outputting various signals, etc. The CPU 101 deploys a program stored in the ROM into the RAM, etc., and executes it. The program stored in the ROM is a program in which the processing procedures of the control device 100 are written. The control device 100 controls each device in the refrigeration cycle device 1 in accordance with these programs. This control is not limited to processing by software, but can also be processed by dedicated hardware (electronic circuitry).

[0062] The control device 100 receives detection signals from the suction pressure sensor 71, the suction temperature sensor 72, the discharge pressure sensor 73, the discharge temperature sensor 74, the frequency sensor 75, and the heat sink temperature sensor 76.

[0063] The control device 100 checks the state of the refrigeration cycle device 1 in accordance with the detection signals of the various sensors input as described above, and outputs control signals to the compressor 4, the first fan 60, the second fan 80, the expansion valve 7, the flow control valve 9, and the flow path switching device 5.

[0064] The control device 100 controls the operating frequency of the compressor 4 using the control signal described above. The control device 100 controls the opening degree of the expansion valve 7 using the control signal described above. The control device 100 controls the opening degree of the expansion valve 7 using the control signal described above. The control device 100 controls the rotation speed of the first fan 60 using the control signal described above. The control device 100 controls the rotation speed of the second fan 80 using the control signal described above. The control device 100 controls the opening degree of the flow rate adjustment valve 9 using the control signal described above. The control device 100 controls the switching of the flow path of the flow path switching device 5 using the control signal described above.

[0065] [Example of First Liquid Pooling Suppression Control] The following describes the liquid pooling suppression control executed in the refrigeration cycle apparatus 1. The liquid pooling suppression control is control executed by the control device 100, and is control that suppresses liquid pooling in the first heat exchanger 6.

[0066] In order to distinguish between the liquid pool suppression control performed in embodiment 1 and the liquid pool suppression control performed in embodiment 2 described later, the liquid pool suppression control performed in embodiment 1 is called the first liquid pool suppression control, and the liquid pool suppression control performed in embodiment 2 described later is called the second liquid pool suppression control.

[0067] First, we will explain the liquid pools in the first heat exchanger 6. Liquid pools in the first heat exchanger 6 are thought to occur for the following reasons. In the first heat exchanger 6 having the structure shown in FIGS. 2 to 6 , the refrigerant flows from the lower to the upper stages of the multiple paths in the first heat exchanger 6. Therefore, the higher the path in the multiple paths, the lower the refrigerant temperature during cooling operation, and the higher the degree of liquefaction of the refrigerant, resulting in a lower refrigerant flow rate. In paths where the refrigerant flow rate is reduced, the refrigerant may stagnate. This state of refrigerant stagnation is called a liquid pool. When such a liquid pool of refrigerant occurs, the refrigerant becomes less likely to flow in the first heat exchanger 6, causing the refrigerant temperature to rise.

[0068] 8 is a flowchart showing the first liquid pooling suppression control according to Embodiment 1. The first liquid pooling suppression control is executed by the CPU 101 of the control device 100 as follows.

[0069] In step S1, the control device 100 acquires the current temperature of the heat sink 20 detected by the heat sink temperature sensor 76. In step S2, the control device 100 determines whether the temperature of the heat sink 20 is equal to or higher than a threshold value. Specifically, in step S2, the control device 100 reads out a threshold value pre-stored in the memory 102 and compares the read-out threshold value with the detected temperature of the heat sink 20 acquired in step S1, thereby determining whether the temperature of the heat sink 20 is equal to or higher than the threshold value.

[0070] The threshold temperature used in step S2 is set to a temperature slightly lower than the set temperature of the higher threshold of the heat sink 20, which is the condition for executing protective control to protect the control board 10 from high temperatures. The threshold used in step S2 is also a threshold for determining that the refrigerant temperature has increased due to the formation of a liquid pool, which makes it difficult for the refrigerant to flow in the first heat exchanger 6 and reduces heat exchange efficiency. The threshold used in step S2 is pre-stored in memory 102. The protective control is a control performed by the control device 100, and when the temperature of the control board 10 becomes higher than or equal to a predetermined threshold, processing is performed to protect the control board 10 from high temperatures, such as reducing the frequency of the compressor 4.

[0071] If it is determined in step S2 that the temperature of the heat sink 20 is not equal to or higher than the threshold value, the control device 100 repeatedly executes steps S1 and S2. On the other hand, if it is determined in step S2 that the temperature of the heat sink 20 is equal to or higher than the threshold value, the control device 100 controls the flow rate control valve 9 of the injection flow path 90 to change from a closed state to an open state in step S3. Specifically, in step S3, the opening degree of the flow rate control valve 9 is increased by one of a plurality of equal divisions of the opening degree at which the flow rate control valve 9 is fully open. By executing step S3, a portion of the refrigerant flowing out of the first heat exchanger 6 is supplied to the intermediate pressure port 41 of the compressor 4 via the injection flow path 90.

[0072] The refrigerant supplied to the compressor 4 in this manner is mixed with the refrigerant drawn from the suction port of the compressor 4, compressed, and then discharged from the compressor 4. As a result, when the refrigerant is supplied to the intermediate pressure port 41 of the compressor 4 via the injection flow path 90 by the control of step S3, the flow rate of the refrigerant discharged from the compressor 4 increases compared to when such refrigerant is not supplied.

[0073] If the temperature of the heat sink 20 is equal to or higher than the threshold value as determined in step S2, it is determined that a liquid pool has formed in the refrigerant path in the first heat exchanger 6, making it difficult for the refrigerant to flow.

[0074] If it is determined in step S2 that the temperature of the heat sink 20 is equal to or higher than the threshold value, it is determined that a liquid pool has formed in the refrigerant flow path in the first heat exchanger 6, and therefore, in the process of step S3, refrigerant is supplied to the intermediate pressure port 41 of the compressor 4 via the injection flow path 90, increasing the flow rate of refrigerant discharged from the compressor 4. As a result, the liquid pool formed in the first heat exchanger 6 can be washed away by the high flow rate of refrigerant and disappear.

[0075] In step S4, the control device 100 acquires the current temperature of the heat sink 20 detected by the heat sink temperature sensor 76. In step S5, the control device 100 determines whether the detected temperature of the heat sink 20 acquired in step S4 is less than a threshold value. This threshold value is the same as the threshold value used for the determination in step S2. Steps S4 and S5 are executed at a predetermined timing after any one of steps S3, S7, and S8 has been executed. This is because a certain amount of time must pass after the flow rate adjustment valve 9 is opened until the detected temperature of the heat sink 20 decreases.

[0076] If the control device 100 determines in step S5 that the detected temperature of the heat sink 20 is not less than the threshold value, it determines in step S6 whether the flow rate adjustment valve 9 is fully open. If the control device 100 determines in step S6 that the flow rate adjustment valve 9 is not fully open, it increases the aperture of the flow rate adjustment valve 9 in step S7 and returns to step S4. Specifically, in step S7, the aperture of the flow rate adjustment valve 9 is increased by one of the multiple equal divisions of the aperture at which the flow rate adjustment valve 9 is fully open. By executing steps S5, S6, and S7, the aperture of the flow rate adjustment valve 9 continues to be increased when the detected temperature of the heat sink 20 is less than the threshold value.

[0077] On the other hand, if it is determined in step S6 that the flow rate adjustment valve 9 is fully open, then in step S8 the control device 100 reduces the frequency of the compressor 4. Specifically, in step S8, a reduction value for the frequency of the compressor 4 is determined in advance, and the control device 100 reduces the frequency of the compressor 4 by the predetermined constant reduction value each time it is determined in step S6 that the flow rate adjustment valve 9 is fully open.

[0078] If it is determined in step S6 that the flow rate adjustment valve 9 is fully open, even if the flow rate adjustment valve 9 is fully open, the detected temperature value of the heat sink 20 has not yet become less than the threshold value, and in step S8, the frequency of the compressor 4 is reduced to lower the temperature of the refrigerant discharged from the compressor 4. In this way, when the temperature of the refrigerant discharged from the compressor 4 decreases, the temperature of the refrigerant flowing into the first heat exchanger 6 decreases, so the effect of the heat of the refrigerant on the control board 10 in the first heat exchanger 6 can be reduced.

[0079] On the other hand, if it is determined in step S5 that the detected temperature of the heat sink 20 is less than the threshold value, the control device 100 changes the flow rate adjustment valve 9 of the injection flow path 90 from the open state to the closed state in step S9. Then, if the control device 100 reduced the frequency of the compressor 4 in step S8, it returns the frequency of the compressor 4 to the normal frequency in step S10 and ends the process. The normal frequency in step S10 is the frequency during normal operation when performing cooling operation, for example, the frequency before the frequency of the compressor 4 was reduced in step S8.

[0080] The processes shown in steps S1 to S10 are repeatedly executed during the cooling operation of the refrigeration cycle device 1.

[0081] 8 is executed, when a liquid pool occurs in the first heat exchanger 6, the refrigerant discharged from the refrigerant outlet side of the first heat exchanger 6 is injected into the intermediate pressure port 41 of the compressor 4 via the injection flow path 90. This increases the flow rate of the refrigerant discharged from the compressor 4 and flowing into the first heat exchanger 6, so that when a liquid pool occurs in the first heat exchanger 6, the ability to drain the liquid pool increases in accordance with the increase in the refrigerant flow rate, thereby making it possible to eliminate the liquid pool.

[0082] 8 is executed, the liquid pool can be eliminated before the protection control is executed to prevent the temperature of the control board 10 from becoming too high, thereby reducing the frequency with which the protection control is executed.

[0083] [Example of change in state of refrigeration cycle due to injection of refrigerant] Next, an example of change in state of refrigeration cycle due to injection of refrigerant will be described. Fig. 9 is a ph diagram showing an example of change in state of refrigeration cycle due to injection of refrigerant.

[0084] First, we will explain the state change of the refrigeration cycle when refrigerant injection is not performed through the injection flow path 90. When the compressor 4 compresses the refrigerant, the state of the refrigerant changes from a first state a before compression to a second state b after compression. When the compressor 4 compresses the refrigerant, the pressure of the refrigerant increases and the specific enthalpy of the refrigerant increases from specific enthalpy h0 before compression to specific enthalpy h1 after compression.

[0085] When the refrigerant discharged from the compressor 4 is condensed in the first heat exchanger 6, the state of the refrigerant changes from a second state b before condensation to a third state c after condensation. When the first heat exchanger 6 condenses the refrigerant, the specific enthalpy of the refrigerant decreases from a specific enthalpy h1 before condensation to a specific enthalpy h2 after condensation while the pressure of the refrigerant is kept constant.

[0086] When the refrigerant condensed in the first heat exchanger 6 is expanded by the expansion valve 7, the state of the refrigerant changes from a third state c before expansion to a fourth state d after expansion. When the expansion valve 7 expands the refrigerant, the refrigerant pressure decreases from a pressure P1 before expansion to a pressure P0 after expansion while the specific enthalpy h2 of the refrigerant remains constant.

[0087] When the refrigerant expanded in the first heat exchanger 6 is evaporated in the second heat exchanger 8, the state of the refrigerant changes from the fourth state d before evaporation to the first state a after evaporation. When the second heat exchanger 8 evaporates the refrigerant, the state of the refrigerant is such that the specific enthalpy of the refrigerant increases from the specific enthalpy h2 before evaporation to the specific enthalpy h0 after evaporation while the refrigerant pressure P0 remains constant.

[0088] Next, a description will be given of a state change of the refrigeration cycle when refrigerant is injected through the injection flow path 90. When refrigerant is injected through the injection flow path 90, inside the compressor 4, the refrigerant having a specific enthalpy h3 and a flow rate G in the fifth state e of the compression process after suction and the refrigerant having a specific enthalpy h2 and a flow rate Gi in the sixth state f injected into the compressor 4 through the injection flow path 90 are merged and mixed. The specific enthalpy h4 of the refrigerant in the sixth state f after such merging can be expressed as h4 = (G × h3 + Gi × h2) / G + Gi. The specific enthalpy h4 of the refrigerant in the sixth state f is lower than the specific enthalpy h3 in the fifth state e of the compression process.

[0089] After the refrigerants are merged, the refrigerant with a flow rate of G+Gi is further compressed from the sixth state f to a pressure P0 in the compressor 4, increasing its pressure and specific enthalpy, and reaches a seventh state g in which the pressure of the refrigerant increases to pressure P0 and the specific enthalpy of the refrigerant increases to specific enthalpy h5.

[0090] The specific enthalpy h5 of the refrigerant in the seventh state g after compression by the compressor 4 when refrigerant injection is performed through the injection flow path 90 is lower than the specific enthalpy h1 of the refrigerant in the second state b after compression by the compressor 4 when injection is not performed. As a result, the temperature of the refrigerant discharged from the compressor 4 is lower when injection is performed than when injection is not performed.

[0091] As described above, when refrigerant is injected into the compressor 4 via the injection flow path 90, the flow rate of the refrigerant increases, thereby eliminating liquid pools in the first heat exchanger 6, compared to when such refrigerant injection is not performed, and further, the temperature of the refrigerant flowing into the first heat exchanger 6 decreases, thereby suppressing the temperature rise of the control board 10.

[0092] Second Embodiment In a second embodiment, an example will be described in which, when a liquid pool occurs in the first heat exchanger 6, second liquid pool suppression control is executed to perform a heating operation until the liquid pool is eliminated.

[0093] [Example of overall configuration of refrigeration cycle apparatus 1A] Fig. 10 is a diagram showing an example of the configuration of a refrigeration cycle apparatus 1A according to embodiment 2. The refrigeration cycle apparatus 1A in Fig. 10 differs from the refrigeration cycle apparatus 1 in Fig. 1 in that the injection flow path 90 and the flow rate control valve 9 shown in Fig. 1 are not provided.

[0094] [Example of Arrangement of Temperature Sensors in Embodiment 2] Fig. 11 is a perspective view of the first heat exchanger 6 showing an example of the arrangement of temperature sensors in Embodiment 2. Referring to Fig. 11, the first heat exchanger 6 is provided with a first pass temperature sensor 81, a second pass temperature sensor 82, a third pass temperature sensor 83, a fourth pass temperature sensor 84, a fifth pass temperature sensor 85, a sixth pass temperature sensor 86, a seventh pass temperature sensor 87, and an eighth pass temperature sensor 88.

[0095] The first path temperature sensor 81 is provided corresponding to the refrigerant path 37a shown in Fig. 3 and detects the temperature of the refrigerant in the refrigerant path 37a. The second path temperature sensor 82 is provided corresponding to the refrigerant path 37b shown in Fig. 3 and detects the temperature of the refrigerant in the refrigerant path 37b. The third path temperature sensor 83 is provided corresponding to the refrigerant path 38a shown in Fig. 3 and detects the temperature of the refrigerant in the refrigerant path 38a. The fourth path temperature sensor 84 is provided corresponding to the refrigerant path 38b shown in Fig. 3 and detects the temperature of the refrigerant in the refrigerant path 38b.

[0096] The fifth path temperature sensor 85 is provided corresponding to the refrigerant path 37c shown in Fig. 3 and detects the temperature of the refrigerant in the refrigerant path 37c. The sixth path temperature sensor 86 is provided corresponding to the refrigerant path 37d shown in Fig. 3 and detects the temperature of the refrigerant in the refrigerant path 37d. The seventh path temperature sensor 87 is provided corresponding to the refrigerant path 38c shown in Fig. 3 and detects the temperature of the refrigerant in the refrigerant path 38c. The eighth path temperature sensor 88 is provided corresponding to the refrigerant path 38d shown in Fig. 3 and detects the temperature of the refrigerant in the refrigerant path 38d.

[0097] The temperature detected by the first path temperature sensor 81 is T1. The temperature detected by the second path temperature sensor 82 is T2. The temperature detected by the third path temperature sensor 83 is T3. The temperature detected by the fourth path temperature sensor 84 is T4. The temperature detected by the fifth path temperature sensor 85 is T5. The temperature detected by the sixth path temperature sensor 86 is T6. The temperature detected by the seventh path temperature sensor 87 is T7. The temperature detected by the eighth path temperature sensor 88 is T8.

[0098] When cooling operation is performed, the refrigerant flows through refrigerant path 37a, refrigerant path 37b, refrigerant path 38a, refrigerant path 38b, refrigerant path 37c, refrigerant path 37d, refrigerant path 38c, and refrigerant path 38d in this order as shown in Fig. 3. As a result, when no liquid pools are present in the first heat exchanger 6, the refrigerant flows normally, and the refrigerant temperature detected during cooling operation decreases with each refrigerant path, with the relationship being T1 > T2 > T3 > T4 > T5 > T6 > T7 > T8.

[0099] On the other hand, when a liquid pool occurs in the first heat exchanger 6, the refrigerant does not flow normally, which may cause some refrigerant paths to have a significantly localized drop in temperature, and the refrigerant temperatures detected during cooling operation do not follow the relationship T1 > T2 > T3 > T4 > T5 > T6 > T7 > T8. Therefore, when the refrigerant temperatures detected during cooling operation do not follow the relationship T1 > T2 > T3 > T4 > T5 > T6 > T7 > T8, the control device 100 may open the flow rate control valve 9 and supply the refrigerant from the injection flow path 90 to the intermediate pressure port 41 of the compressor 4.

[0100] [Example of Control Configuration in Embodiment 2] Fig. 12 is a block diagram showing an example of a control configuration of the refrigeration cycle apparatus 1A according to Embodiment 2. The control configuration of the refrigeration cycle apparatus 1A in Fig. 12 differs from the control configuration of the refrigeration cycle apparatus 1 in Fig. 7 in that a first pass temperature sensor 81, a second pass temperature sensor 82, a third pass temperature sensor 83, a fourth pass temperature sensor 84, a fifth pass temperature sensor 85, a sixth pass temperature sensor 86, a seventh pass temperature sensor 87, and an eighth pass temperature sensor 88 are provided. Detection signals from these first pass temperature sensor 81 to eighth pass temperature sensor 88 are input to the control device 100.

[0101] 13 is a flowchart showing the second liquid pooling prevention control according to embodiment 2. The second liquid pooling prevention control is executed by the CPU 101 of the control device 100 as follows: As shown in step S20, the second liquid pooling prevention control is executed when the occurrence of liquid pooling is detected during cooling operation.

[0102] In step S21, the control device 100 acquires the detected temperature values ​​T1, T2, . . . T8 of the refrigerant paths 37a to 37d and 38a to 38d in response to the detection signals of the first path temperature sensor 81 to the eighth path temperature sensor 88.

[0103] In step S22, the control device 100 determines whether the detected temperature values ​​of the refrigerant paths 37a to 37d, 38a to 38d obtained in step S21 are in the relationship T1>T2>T3>T4>T5>T6>T7>T8.

[0104] If it is determined in step S22 that the detected temperatures of the refrigerant paths 37a to 37d, 38a to 38d are in the relationship T1>T2>T3>T4>T5>T6>T7>T8, the control device 100 determines in step S27 that no liquid pool has occurred in the first heat exchanger 6, continues air conditioning operation, and terminates the processing.

[0105] On the other hand, if it is determined in step S22 that the detected temperatures of the refrigerant paths 37a to 37d and 38a to 38d do not satisfy the relationship T1 > T2 > T3 > T4 > T5 > T6 > T7 > T8, the control device 100 determines in step S23 that a liquid pool has occurred in the first heat exchanger 6 and starts heating operation. Specifically, in step S23, the compressor 4 is stopped to end the cooling operation, and then the flow path switching device 5 switches the refrigerant path to the heating path and the compressor 4 is operated to start the heating operation.

[0106] In step S24, the control device 100 determines whether the period since the start of the heating operation has reached a specified period. Specifically, the control device 100 starts the operation of a timer when the heating operation is started in step S23, and measures the period since the start of the heating operation. In step S24, it is determined whether the period measured by the timer has reached the specified period. The specified period used in step S24 is, for example, a period of several minutes less than 10 minutes. Note that the specified period used in step S24 may be a period of 10 minutes or more.

[0107] In this way, when a liquid pool occurs in the first heat exchanger 6, when the cooling operation is switched to the heating operation, the refrigerant flows in the opposite direction to that in the cooling operation in the first heat exchanger 6. As a result, the refrigerant flows in order from the refrigerant path where liquid pooling is likely to occur in the cooling operation, thereby eliminating the liquid pooling.

[0108] If it is determined in step S24 that the period since the start of the heating operation has reached the specified period, the control device 100 terminates the heating operation in step S25. Specifically, in step S25, the compressor 4 is stopped to terminate the heating operation. In step S26, the control device 100 starts the cooling operation. Specifically, in step S26, the flow path switching device 5 switches the refrigerant path to the cooling path, and the compressor 4 is operated to start the cooling operation.

[0109] The reason why the heating operation is terminated when the period since the start of the heating operation reaches the specified period is as follows: The heating operation executed in the second liquid accumulation prevention control only needs to be executed for the minimum period necessary to eliminate liquid accumulation during the cooling operation.

[0110] After the cooling operation is started in step S26, the control device 100 acquires the detected temperature values ​​of the refrigerant paths 37a to 37d, 38a to 38d in step S21 according to the detection signals of the first path temperature sensor 81 to the eighth path temperature sensor 88, when a predetermined period of time has elapsed.

[0111] In step S22, the control device 100 determines whether the detected temperature values ​​of the refrigerant paths 37a to 37d, 38a to 38d obtained in step S21 are in the relationship T1>T2>T3>T4>T5>T6>T7>T8.

[0112] Thereafter, in step S22, if it is determined that the detected temperature values ​​of the refrigerant paths 37a to 37d, 38a to 38d obtained in step S21 do not satisfy the relationship T1>T2>T3>T4>T5>T6>T7>T8, the control device 100 determines that a liquid pool has still occurred in the first heat exchanger 6, and repeatedly executes the processing of the above-mentioned steps S23 to S26 and S21.

[0113] On the other hand, in step S22, if it is determined that the detected temperature values ​​of the refrigerant paths 37a to 37d, 38a to 38d obtained in step S21 are in the relationship T1>T2>T3>T4>T5>T6>T7>T8, the control device 100 determines that no liquid pool has occurred in the first heat exchanger 6, and in step S27, continues air conditioning operation and ends the processing.

[0114] As described above, in the second embodiment, when a liquid pool occurs in the first heat exchanger 6, the control device 100 executes the second liquid pool suppression control, which executes the heating operation until the liquid pool is eliminated. When the second liquid pool suppression control is executed when a liquid pool occurs in the first heat exchanger 6, the heating operation is executed, and the refrigerant flows in order from the refrigerant path where liquid pools are likely to occur during the cooling operation, thereby eliminating the liquid pool. By eliminating the liquid pool in this way, a decrease in the heat exchange capacity of the first heat exchanger 6 is suppressed, and an increase in the temperature of the control board 10 is suppressed.

[0115] 8 , the first embodiment has described an example in which the control device 100 executes the first liquid accumulation suppression control in which, when the temperature of the heat sink 20 becomes higher than a threshold value, the flow rate adjustment valve 9 is opened to supply the refrigerant from the injection passage 90 to the intermediate pressure port 41 of the compressor 4. This first liquid accumulation suppression control may be modified, as in the second liquid accumulation suppression control described in FIG. 13 , by providing first to eighth path temperature sensors 81 to 88 and opening the flow rate adjustment valve 9 to supply the refrigerant from the injection passage 90 to the intermediate pressure port 41 of the compressor 4 when the refrigerant temperatures detected during cooling operation do not satisfy the relationship T1 > T2 > T3 > T4 > T5 > T6 > T7 > T8.

[0116] (2) In the second embodiment, the first path temperature sensor 81 to the eighth path temperature sensor 88 are provided, and the control device 100 executes the heating operation when the refrigerant temperatures detected during the cooling operation do not satisfy the relationship T1 > T2 > T3 > T4 > T5 > T6 > T7 > T8, as in the second liquid accumulation suppression control described in Fig. 13. In this second liquid accumulation suppression control, the control device 100 may execute the heating operation when the temperature of the heat sink 20 becomes higher than the threshold value, as in the first liquid accumulation suppression control described in Fig. 8.

[0117] (3) In the first embodiment, the refrigerant path of the first heat exchanger 6 is configured to be divided into two rows as shown in Figures 2 to 4. However, this is not limiting, and the refrigerant path of the first heat exchanger 6 may be configured to be divided into three or more rows, such as three or four rows.

[0118] (4) In the first embodiment, the timing for opening the flow rate adjustment valve 9 of the injection flow path 90 is before the execution of the above-described protective control, as described in Fig. 8. However, the present invention is not limited to this, and the control device 100 may execute control such that the timing for opening the flow rate adjustment valve 9 of the injection flow path 90 is after the execution of the above-described protective control.

[0119] (5) In the first embodiment, an example has been shown in which control is executed to reduce the frequency of the compressor 4 in step S8 as shown in Fig. 8. However, in a configuration in which the temperature of the heat sink 20 can be sufficiently reduced by opening the flow rate adjustment valve 9 of the injection flow path 90, a control program may be used that does not execute control to reduce the frequency of the compressor 4 in step S8 shown in Fig. 8.

[0120] [Summary of the embodiment] Hereinafter, the embodiment will be summarized again with reference to the drawings.

[0121] (Item 1) A refrigeration cycle device (refrigeration cycle device 1) includes a compressor (compressor 4), a first heat exchanger (first heat exchanger 6), an expansion valve (expansion valve 7), and a second heat exchanger (second heat exchanger 8), and is equipped with a refrigerant circuit (refrigerant circuit 50) through which a refrigerant circulates, and a control board (control board 10). The first heat exchanger (first heat exchanger 6) includes refrigerant paths (first row refrigerant path 31, second row refrigerant path 32) into which refrigerant discharged from the compressor (compressor 4) flows, and in the refrigerant paths (first row refrigerant path 31, second row refrigerant path 32), heat exchange occurs between the flowing refrigerant and a cooling medium. The control board (control board 10) is provided in a position above the refrigerant path in the first heat exchanger (first heat exchanger 6), and the refrigerant path (first row refrigerant path 31, second row refrigerant path 32) of the first heat exchanger (first heat exchanger 6) includes a plurality of stages of paths (refrigerant paths 37a to 37d, 38a to 38d) connected in a vertical direction, and the first heat exchanger (first heat exchanger 6) causes the refrigerant to flow into the refrigerant path (first row refrigerant path 31, second row refrigerant path 32) from the lowest stage path of the plurality of stages of paths (refrigerant paths 37a to 37d, 38a to 38d). and an outlet path (outlet path 15) that allows the refrigerant to flow out of the refrigerant paths (first row refrigerant path 31, second row refrigerant path 32) from the uppermost path in the plurality of paths (refrigerant paths 37a to 37d, 38a to 38d), and the refrigerant that flows from the inlet path into the refrigerant paths (first row refrigerant path 31, second row refrigerant path 32) flows from the lowermost path to the uppermost path in the plurality of paths, and the first heat exchanger (first heat exchanger 6) is configured such that the refrigerant paths (first row refrigerant path 31, second row refrigerant path 32) are connected to the first row refrigerant path. The first-row refrigerant path (first-row refrigerant path 31) and the second-row refrigerant path (second-row refrigerant path 32) are connected by connection pipes (connection pipes 12, 13, 14). The inlet path (inlet path 11) is provided in the lowest path of the plurality of paths (refrigerant paths 37a to 37d, 38a to 38d) in the first-row refrigerant path (first-row refrigerant path 31). The second-row refrigerant path (second-row refrigerant path 32) is provided in the lowest path of the plurality of paths (refrigerant paths 37a to 37d,38a to 38d), the outlet path (outlet path 15) is provided in the uppermost path.

[0122] According to this configuration, the control board is disposed above the refrigerant path in the first heat exchanger. In the first heat exchanger, the refrigerant path into which the refrigerant discharged from the compressor flows is configured such that the refrigerant flows in through the lowest path of the multiple paths and flows out through the highest path of the multiple paths. Thus, the high-temperature refrigerant discharged from the compressor flows into the refrigerant path of the first heat exchanger through the lowest path far from the control board, exchanges heat with the cooling medium, and then flows out through the highest path closest to the control board in a cooled state. Therefore, the control board is prevented from receiving heat from the high-temperature refrigerant discharged from the compressor. This configuration prevents the refrigeration cycle apparatus from experiencing a temperature rise in the control board and a decrease in the heat exchange capacity of the first heat exchanger. Furthermore, in the first heat exchanger, the refrigerant path is divided into two rows, a first row refrigerant path and a second row refrigerant path, and an inlet path is provided in the lowest row of the multiple paths in the first row refrigerant path, and an outlet path is provided in the highest row of the multiple paths in the second row refrigerant path.This improves the heat exchange capacity of the first heat exchanger compared to when the refrigerant path is a single row, thereby suppressing a decrease in the heat exchange capacity of the first heat exchanger.

[0123] (Item 2) In the refrigeration cycle apparatus (refrigeration cycle apparatus 1) described in item 1, there is provided a first flow path (expansion valve flow path 70) through which a refrigerant flows, which is provided between the outflow path of the first heat exchanger (first heat exchanger 6) and the expansion valve (expansion valve 7), a second flow path (injection flow path 90) through which a refrigerant flows, which is provided between the outflow path of the first heat exchanger (first heat exchanger 6) and an intermediate pressure port (intermediate pressure port 41) of the compressor (compressor 4), and a flow rate control valve (flow rate control valve 9) provided in the second flow path (injection flow path 90) to control a flow rate of the refrigerant in the second flow path (injection flow path 90). The cooling system further includes a heat sink (heat sink 20) ​​provided in contact with the control board (control board 10) at a position above the refrigerant path (first row refrigerant path 31, second row refrigerant path 32) of the first heat exchanger (first heat exchanger 6), and a temperature sensor (heat sink temperature sensor 76) that detects the temperature of the heat sink (heat sink 20), and the control board (control board 10) includes a control device (control device 100), and the control device (control device 100) controls the flow rate control valve (flow rate control valve 9) in accordance with the temperature detected by the temperature sensor (heat sink temperature sensor 76).

[0124] According to this configuration, a second flow path through which the refrigerant flows is provided between the outlet path of the first heat exchanger and the intermediate pressure port of the compressor, and a flow rate control valve provided in the second flow path is controlled in response to the temperature of the heat sink detected by the temperature sensor. As a result, the refrigerant is supplied from the first heat exchanger to the intermediate pressure port of the compressor in response to the temperature state of the control board. When the refrigerant is supplied to the intermediate pressure port of the compressor, the refrigerant flow rate discharged from the compressor increases. Therefore, in the case where a liquid pool forms in the refrigerant path of the first heat exchanger 6, reducing the heat exchange efficiency and causing the temperature of the control board to rise, the increased refrigerant flow rate eliminates the liquid pool, preventing a decrease in the heat exchange capacity of the first heat exchanger and preventing the temperature rise of the control board.

[0125] (Item 3) A refrigeration cycle apparatus (refrigeration cycle apparatus 1A) includes a compressor (compressor 4), a first heat exchanger (first heat exchanger 6), an expansion valve (expansion valve 7), and a second heat exchanger (second heat exchanger 8), and is equipped with a refrigerant circuit (refrigerant circuit 50) through which a refrigerant circulates, and a control board (control board 10). The first heat exchanger (first heat exchanger 6) includes refrigerant paths (first row refrigerant path 31, second row refrigerant path 32) into which refrigerant discharged from the compressor (compressor 4) flows, and in the refrigerant paths (first row refrigerant path 31, second row refrigerant path 32), heat exchange occurs between the flowing refrigerant and a cooling medium. The control board (control board 10) is provided in the first heat exchanger (first heat exchanger 6) at a position above the refrigerant paths (first row refrigerant path 31, second row refrigerant path 32). The refrigerant paths (first row refrigerant path 31, second row refrigerant path 32) include a plurality of stages of paths (refrigerant paths 37a to 37d, 38a to 38d) connected in a vertical direction, and the first heat exchanger (first heat exchanger 6) includes an inflow path (inflow path 11) that allows refrigerant to flow from the lowest stage path of the plurality of stages of paths (refrigerant paths 37a to 37d, 38a to 38d) into the refrigerant paths (first row refrigerant path 31, second row refrigerant path 32). ), and an outflow path (outflow path 15) that allows the refrigerant to flow out of the refrigerant paths (first-row refrigerant path 31, second-row refrigerant path 32) from the uppermost path in the multiple stages of paths (refrigerant paths 37a to 37d, 38a to 38d), and the refrigerant that has flowed from the inflow path (inflow path 11) into the refrigerant paths (first-row refrigerant path 31, second-row refrigerant path 32) is38a to 38d), the refrigerant flows from the lowest path to the highest path, and is provided between the outlet path (outlet path 15) of the first heat exchanger (first heat exchanger 6) and the expansion valve (expansion valve 7), and the refrigerant flows through a first flow path (expansion valve flow path 70); a second flow path (injection flow path 90) provided between the outlet path (outlet path 15) of the first heat exchanger (first heat exchanger 6) and an intermediate pressure port (intermediate pressure port 41) of the compressor (compressor 4), and the refrigerant flows through; and a flow rate control valve (flow rate control valve) provided in the second flow path (injection flow path 90) and controlling the flow rate of the refrigerant in the second flow path (injection flow path 90). The control circuit further includes a flow rate control valve (flow rate control valve 9), a heat sink (heat sink 20) ​​provided in contact with the control board (control board 10) at a position above the refrigerant path (first row refrigerant path 31, second row refrigerant path 32) of the first heat exchanger (first heat exchanger 6), and a temperature sensor (heat sink temperature sensor 76) that detects the temperature of the heat sink (heat sink 20). The control board (control board 10) includes a control device (control device 100), and the control device (control device 100) controls the flow rate control valve (flow rate control valve 9) according to the temperature detected by the temperature sensor (heat sink temperature sensor 76).

[0126] According to this configuration, the control board is disposed above the refrigerant path in the first heat exchanger. The refrigerant path in the first heat exchanger receives the refrigerant discharged from the compressor. The refrigerant flows into the lowest path of the multiple paths and flows out of the highest path. The high-temperature refrigerant discharged from the compressor flows into the refrigerant path of the first heat exchanger from the lowest path farthest from the control board, exchanges heat with the cooling medium, and then flows out of the highest path closest to the control board. This prevents the control board from receiving heat from the high-temperature refrigerant discharged from the compressor. This prevents the refrigeration cycle apparatus from experiencing a temperature rise in the control board and a decrease in the heat exchange capacity of the first heat exchanger. Furthermore, a second flow path through which the refrigerant flows is disposed between the outlet of the first heat exchanger and the intermediate-pressure port of the compressor. A flow control valve disposed in the second flow path is controlled in response to the temperature of the heat sink detected by a temperature sensor. As a result, refrigerant is supplied from the first heat exchanger to the intermediate pressure port of the compressor according to the temperature state of the control board. When refrigerant is supplied to the intermediate pressure port of the compressor, the flow rate of refrigerant discharged from the compressor increases. Therefore, if a liquid pool forms in the refrigerant path of the first heat exchanger 6, reducing heat exchange efficiency and causing the temperature of the control board to rise, the increased refrigerant flow rate can eliminate the liquid pool, preventing a decrease in the heat exchange capacity of the first heat exchanger and preventing the temperature rise of the control board.

[0127] (4) In the refrigeration cycle device (refrigeration cycle device 1, 1A) described in paragraph 2 or paragraph 3, the control device (control device 100) controls the flow rate control valve (flow rate control valve 9) to an open state when the temperature detected by the temperature sensor (heat sink temperature sensor 76) is equal to or higher than a threshold value (steps S3, S7).

[0128] With this configuration, the flow control valve is controlled to an open state when the temperature of the heat sink detected by the temperature sensor is equal to or higher than a threshold value. Therefore, for example, if the threshold value is set to the heat sink temperature at which liquid pooling is thought to occur in the first heat exchanger, the flow control valve can be controlled to an open state, thereby eliminating liquid pooling in the first heat exchanger.

[0129] (Item 5) In the refrigeration cycle device (refrigeration cycle device 1, 1A) described in Item 4, after controlling the flow rate control valve (flow rate control valve 9) to an open state, if the temperature detected by the temperature sensor (heat sink temperature sensor 76) becomes less than the threshold value, the control device (control device 100) controls the flow rate control valve (flow rate control valve 9) to a closed state (step S9).

[0130] With this configuration, when the temperature of the heat sink detected by the temperature sensor falls below the threshold value, the flow control valve is controlled to a closed state, thereby preventing more refrigerant than necessary from being supplied from the first heat exchanger to the intermediate pressure port of the compressor.

[0131] (Item 6) In the refrigeration cycle apparatus (refrigeration cycle apparatus 1A) described in item 1, the refrigerant circuit (refrigerant circuit 50) further includes a flow path switching device (flow path switching device 5) that switches a flow path of the refrigerant discharged from the compressor (compressor 4) between a third flow path (third flow path 51) through which the refrigerant flows into the first heat exchanger (first heat exchanger 6) and a fourth flow path (fourth flow path 52) through which the refrigerant flows into the second heat exchanger (second heat exchanger 8), and further includes a plurality of temperature sensors (first path temperature sensor 81 to eighth path temperature sensor 88) that are provided corresponding to the plurality of stages of paths (refrigerant paths 37a to 37d, 38a to 38d) and detect the temperatures of the refrigerant in the corresponding paths, and the control device (control device 10) 0) controls the flow path switching device (flow path switching device 5) to switch the flow path of the refrigerant discharged from the compressor (compressor 4) to the third flow path (third flow path 51) when the temperatures detected by the plurality of temperature sensors (first path temperature sensor 81 to eighth path temperature sensor 88) in the multiple stages of paths (refrigerant paths 37a to 37d, 38a to 38d) are higher in the lower stages of paths, and to switch the flow path of the refrigerant discharged from the compressor (compressor 4) to the fourth flow path (fourth flow path 52) for a certain period of time when the temperatures detected by the plurality of temperature sensors (first path temperature sensor 81 to eighth path temperature sensor 88) are not higher in the lower stages of paths.

[0132] With this configuration, if the temperatures detected by the temperature sensors corresponding to the multiple paths are higher in the lower paths, it can be determined that no liquid pool has occurred in the first heat exchanger, and the flow path of the refrigerant discharged from the compressor is switched to the third flow path, and cooling operation is performed. On the other hand, if the temperatures detected by the temperature sensors corresponding to the multiple paths are not higher in the lower paths, it can be determined that liquid pool has occurred in the first heat exchanger, and the flow path of the refrigerant discharged from the compressor is switched to the fourth flow path, and heating operation is performed. In the first heat exchanger, refrigerant flows in the opposite direction to that in cooling operation during heating operation, and this refrigerant flow can eliminate liquid pools.

[0133] (Item 7) In the refrigeration cycle device (refrigeration cycle device 1, 1A) described in Items 1 to 6, the first heat exchanger (first heat exchanger 6) has a different number of refrigerant pipes (refrigerant pipes 39) constituting the refrigerant path in each of the multiple stages of paths (refrigerant paths 37a to 37d, 38a to 38d), and the higher the path, the fewer the number of refrigerant pipes (refrigerant pipes 39).

[0134] With this configuration, the number of refrigerant pipes in the upper paths of the first heat exchanger is smaller, so that the refrigerant can flow efficiently in the first heat exchanger, where the refrigerant flows from the lowest path to the highest path.

[0135] The embodiments disclosed herein are examples and are not intended to be limiting. The scope of the present disclosure is defined by the scope of the claims, not the scope described above, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

[0136] 1, 1A refrigeration cycle device, 4 compressor, 6 first heat exchanger, 7 expansion valve, 8 second heat exchanger, 50 refrigerant circuit, 10 control board, 31 first row refrigerant path, 32 second row refrigerant path, 37a, 37b, 37c, 37d, 38a, 38b, 38c, 38d refrigerant paths, 11 inlet path, 15 outlet path, 70 expansion valve path, 41 intermediate pressure port, 9 flow control valve, 20 heat sink, 26 heat sink temperature sensor, 51 third path, 52 fourth path, 81 first path temperature sensor, 82 second path temperature sensor, 83 third path temperature sensor, 84 fourth path temperature sensor, 85 fifth path temperature sensor, 86 sixth path temperature sensor, 87 seventh path temperature sensor, 88 eighth path temperature sensor.

Claims

1. A refrigerant circuit including a compressor, a first heat exchanger, an expansion valve, and a second heat exchanger, through which a refrigerant circulates, and a control board, wherein the first heat exchanger includes a refrigerant path into which refrigerant discharged from the compressor flows, and heat is exchanged in the refrigerant path between the flowing refrigerant and a cooling medium, the control board is provided in a position above the refrigerant path in the first heat exchanger, and the refrigerant path of the first heat exchanger includes a plurality of paths connected in a vertical direction, and the first heat exchanger further includes an inlet path that allows refrigerant to flow from a lowest path in the plurality of paths into the refrigerant path, and an outlet path that allows refrigerant to flow from an uppermost path in the plurality of paths to the outside of the refrigerant path, and the refrigerant that flows from the inlet path into the refrigerant path flows in the plurality of paths from the lowest path to the uppermost path, the first heat exchanger has a refrigerant path divided into two rows, a first row refrigerant path and a second row refrigerant path; the first row refrigerant path and the second row refrigerant path are connected by a connection pipe; the inlet path is provided in a lowest path of the multiple stages of paths in the first row refrigerant path; and the outlet path is provided in an uppermost path of the multiple stages of paths in the second row refrigerant path.

2. A refrigeration cycle device as described in claim 1, further comprising: a first flow path provided between the outlet path of the first heat exchanger and the expansion valve, through which a refrigerant flows; a second flow path provided between the outlet path of the first heat exchanger and an intermediate pressure port of the compressor, through which a refrigerant flows; a flow rate adjustment valve provided in the second flow path, which adjusts the flow rate of the refrigerant in the second flow path; a heat sink provided in contact with the control board at a position above the refrigerant path of the first heat exchanger; and a temperature sensor that detects the temperature of the heat sink, wherein the control board includes a control device, and the control device controls the flow rate adjustment valve in accordance with the temperature detected by the temperature sensor.

3. A refrigerant circuit including a compressor, a first heat exchanger, an expansion valve, and a second heat exchanger, and through which a refrigerant circulates; and a control board, wherein the first heat exchanger includes a refrigerant path into which refrigerant discharged from the compressor flows, and heat is exchanged in the refrigerant path between the flowing refrigerant and a cooling medium, the control board is provided in the first heat exchanger at a position higher than the refrigerant path, and the refrigerant path of the first heat exchanger includes a plurality of paths connected in a vertical direction, and the first heat exchanger further includes: an inlet path for allowing refrigerant to flow from the lowest path of the plurality of paths into the refrigerant path, and an outlet path for allowing refrigerant to flow from the highest path of the plurality of paths to the outside of the refrigerant path, and the refrigerant that has flowed from the inlet path into the refrigerant path flows in the plurality of paths from the lowest path to the highest path, and a first flow path provided between the outlet path of the first heat exchanger and the expansion valve, and through which the refrigerant flows, a second flow path through which a refrigerant flows, the second flow path being provided between the outlet path of the first heat exchanger and an intermediate pressure port of the compressor; a flow rate adjustment valve provided in the second flow path and adjusting a flow rate of the refrigerant in the second flow path; a heat sink provided in contact with the control board at a position above the refrigerant path of the first heat exchanger; and a temperature sensor for detecting a temperature of the heat sink, wherein the control board includes a control device, and the control device controls the flow rate adjustment valve in accordance with the temperature detected by the temperature sensor.

4. A refrigeration cycle device according to claim 2 or 3, wherein the control device controls the flow rate control valve to an open state when the temperature detected by the temperature sensor is equal to or higher than a threshold value.

5. A refrigeration cycle device as described in claim 4, wherein the control device controls the flow rate control valve to a closed state when the temperature detected by the temperature sensor becomes less than the threshold value after controlling the flow rate control valve to an open state.

6. The refrigeration cycle apparatus according to claim 1, wherein the refrigerant circuit further includes a flow path switching device that switches the flow path of the refrigerant discharged from the compressor between a third flow path through which the refrigerant flows into the first heat exchanger and a fourth flow path through which the refrigerant flows into the second heat exchanger, and further includes a plurality of temperature sensors that are provided corresponding to each of the multiple stages of paths and detect the temperature of the refrigerant in the corresponding path, and the control device controls the flow path switching device to switch the flow path of the refrigerant discharged from the compressor to the third flow path when the temperatures detected by the multiple temperature sensors in the multiple stages of paths are higher as the paths become lower, and to switch the flow path of the refrigerant discharged from the compressor to the fourth flow path for a certain period of time when the temperatures detected by the multiple temperature sensors are not higher as the paths become lower.

7. A refrigeration cycle device according to any one of claims 1 to 6, wherein the first heat exchanger has a different number of refrigerant pipes constituting the refrigerant path in each of the multiple paths, and the higher the path, the fewer the number of refrigerant pipes.

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