Air conditioner

Abstract

This air conditioner comprises: a refrigeration cycle having an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve, through each of which a refrigerant circulates in the stated order; a four-way valve capable of performing a warming operation and a cooling operation by switching the direction of refrigerant flow; a liquid / gas heat exchanger capable of exchanging heat between low-pressure-side gas refrigerant and high-pressure-side liquid refrigerant; and a switching unit for guiding the liquid refrigerant to the liquid / gas heat exchanger in either the warming operation or the cooling operation. The liquid / gas heat exchanger has a storage space in which the circulating liquid refrigerant is stored.

Description

air conditioner

[0001] This application claims priority to Japanese Patent Application No. 2023-141945, filed on September 1, 2023, the contents of which are incorporated herein by reference.

[0002] Generally, a receiver capable of temporarily storing refrigerant is provided in the flow path of the refrigeration cycle of an air conditioner. This receiver adjusts the amount of refrigerant supplied to the circuit (see Patent Document 1 below). Liquid-gas heat exchangers are also known that exchange heat between gas and liquid refrigerants to improve performance.

[0003] Japanese Patent Application Publication No. 8-159587

[0004] However, when the receiver and liquid-to-gas heat exchanger are installed separately, the internal volume of the refrigeration cycle pipe (the total volume of the flow path through which the refrigerant passes) increases, which necessitates an increase in the amount of refrigerant to be sealed inside. This is because the pipe needs to be constantly filled with refrigerant. Therefore, there has been a growing demand for air conditioners that use a liquid-to-gas heat exchanger but require a reduced amount of refrigerant.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an air conditioner that uses a liquid-gas heat exchanger but reduces the amount of refrigerant used.

[0006] In order to solve the above problems, the air conditioner of the present disclosure comprises a refrigeration cycle having an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve, through which refrigerant flows sequentially, a four-way valve that enables heating operation and cooling operation by switching the direction of refrigerant flow, a liquid-gas heat exchanger that can exchange heat between gas refrigerant on the low-pressure side and liquid refrigerant on the high-pressure side, and a switching unit that directs liquid refrigerant to the liquid-gas heat exchanger in either the heating operation or the cooling operation, and the liquid-gas heat exchanger has a storage space in which the circulating liquid refrigerant is stored.

[0007] The air conditioner of the present disclosure comprises a refrigeration cycle having an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve through which refrigerant flows sequentially, a four-way valve that enables heating operation and cooling operation by switching the direction of refrigerant flow, a liquid-gas heat exchanger that can exchange heat between gas refrigerant on a low-pressure side and liquid refrigerant on a high-pressure side, a switching unit that directs liquid refrigerant to the liquid-gas heat exchanger in at least one of the heating operation and the cooling operation, and another expansion valve provided between the switching unit and the indoor heat exchanger, and the liquid-gas heat exchanger has a storage space in which the circulating liquid refrigerant is stored.

[0008] According to the present disclosure, it is possible to provide an air conditioner that uses a liquid-gas heat exchanger but reduces the amount of refrigerant used.

[0009] FIG. 1 is a circuit diagram of an air conditioner according to a first embodiment of the present disclosure, showing a state during heating operation. FIG. 2 is a circuit diagram of an air conditioner according to a first embodiment of the present disclosure, showing a state during cooling operation. FIG. 3 is a circuit diagram of an air conditioner according to a second embodiment of the present disclosure, showing a state during heating operation. FIG. 4 is a circuit diagram of an air conditioner according to a second embodiment of the present disclosure, showing a state during cooling operation. FIG. 5 is a circuit diagram of an air conditioner according to a third embodiment of the present disclosure, showing a state during heating operation. FIG. 6 is a circuit diagram of an air conditioner according to a third embodiment of the present disclosure, showing a state during cooling operation. FIG. 7 is a schematic diagram showing the configuration of a liquid-gas heat exchanger according to each embodiment of the present disclosure. FIG. 8 is a schematic diagram showing modified examples of the liquid-gas heat exchanger according to each embodiment of the present disclosure.

[0010] <First embodiment> (Configuration of air conditioner 1) An air conditioner 1 according to a first embodiment of the present disclosure will now be described with reference to Figures 1 and 2. As shown in Figure 1, the air conditioner 1 includes a refrigeration cycle 10, a four-way valve 20, a liquid-to-gas heat exchanger 30, a switching unit 40, a first flow path 50, a second flow path 60, and a third flow path 70.

[0011] The refrigeration cycle 10 is a circuit for performing heat exchange between the indoor air and the refrigerant, and between the outdoor air and the refrigerant, by compressing and expanding the refrigerant that flows sequentially through each device in the refrigeration cycle 10. Fig. 1 shows the air conditioner 1 in heating operation. Below, the flow of the refrigerant and the operation of each device during heating operation will be explained, and Fig. 2 will explain the flow of the refrigerant and the operation of each device during cooling operation.

[0012] 1 , the refrigeration cycle 10 includes a compressor 11, an indoor heat exchanger 12, an indoor fan 13, an expansion valve 14, an outdoor heat exchanger 15, and an outdoor fan 16. The compressor 11, the indoor heat exchanger 12, the expansion valve 14, and the outdoor heat exchanger 15 are arranged in this order on a first flow path 50 that forms an annular shape.

[0013] The compressor 11 is a rotary machine of, for example, a scroll type or a rotary type, and compresses the refrigerant in the first flow path 50. The indoor heat exchanger 12 is provided downstream of the compressor 11 in the first flow path 50. The indoor heat exchanger 12 is disposed indoors to exchange heat between the refrigerant and the air in the room. An indoor fan 13 is provided next to the indoor heat exchanger 12. The indoor fan 13 is provided to forcibly supply indoor air toward the indoor heat exchanger 12 and promote heat exchange with the refrigerant. The indoor heat exchanger 12 is a heat exchanger of, for example, a fin-and-tube type or a flat tube type.

[0014] An expansion valve 14 is provided downstream of the indoor heat exchanger 12 in the first flow path 50. The expansion valve 14 is a solenoid valve whose opening degree can be adjusted by an external signal. When the refrigerant passes through the expansion valve 14, the refrigerant expands and its pressure decreases. An outdoor heat exchanger 15 is provided downstream of the expansion valve 14 in the first flow path 50. The outdoor heat exchanger 15 is disposed outdoors to exchange heat between the outdoor air and the refrigerant. An outdoor fan 16 is provided adjacent to the outdoor heat exchanger 15. The outdoor fan 16 is provided to forcibly supply outdoor air toward the outdoor heat exchanger 15 to promote heat exchange with the refrigerant. The outdoor heat exchanger 15 is, for example, a fin-and-tube type or flat tube type heat exchanger.

[0015] In this embodiment, the amount of refrigerant is set so that excess refrigerant is generated during heating operation.

[0016] (Configuration of four-way valve 20) A four-way valve 20 is provided in the first flow path 50 between the compressor 11 and the indoor heat exchanger 12. During heating operation, the four-way valve 20 switches the flow path so that the refrigerant flows from the compressor 11 to the indoor heat exchanger 12, as shown in Fig. 1. On the other hand, during cooling operation, the four-way valve 20 switches the flow path so that the refrigerant flows from the compressor 11 to the outdoor heat exchanger 15, as shown in Fig. 2. In addition, the four-way valve 20 is also connected to a second flow path 60 that is connected to the liquid-gas heat exchanger 30, as will be described in detail later.

[0017] (Configuration of Liquid-Gas Heat Exchanger 30) An annular second flow path 60 is provided between one port of the four-way valve 20 and the inlet end of the compressor 11. The liquid-gas heat exchanger 30 is provided on this second flow path 60. The liquid-gas heat exchanger 30 exchanges heat between the low-temperature, low-pressure gas refrigerant flowing out from the outdoor heat exchanger 15 and the high-temperature, high-pressure liquid refrigerant flowing out from the indoor heat exchanger 12. Specifically, as shown in FIG. 7 , the liquid-gas heat exchanger 30 has a gas piping section 31, a liquid piping section 32, and a storage space 33. The gas piping section 31 is connected to the suction side of the compressor 11. The low-temperature, low-pressure gas refrigerant flows through the gas piping section 31 before being drawn into the compressor 11. The liquid piping section 32 covers the gas piping section 31 from the outside. The liquid refrigerant flows through the liquid piping section 32 in a direction opposite to the refrigerant flowing through the gas piping section 31. A part of the liquid piping section 32 is made into a storage space 33, and excess liquid refrigerant is stored in the storage space 33 as needed. In other words, the storage space 33 has the function of a conventional receiver.

[0018] (Configuration of switching unit 40) Another four-way valve 20 serving as the switching unit 40 is provided on the first flow path 50 between the indoor heat exchanger 12 and the expansion valve 14. The switching unit 40 and the liquid-gas heat exchanger 30 are connected by an annular third flow path 70. In other words, by switching the open state of the switching unit 40, the flow of refrigerant toward the liquid-gas heat exchanger 30 changes.

[0019] (Operation during heating operation) Next, the operation during heating operation of the air conditioner 1 will be described with reference to Fig. 1. Note that solid arrows in Figs. 1 to 6 indicate the flow of a relatively low-temperature refrigerant, and dashed arrows indicate the flow of a relatively high-temperature refrigerant.

[0020] When the compressor 11 is driven, the refrigerant in the first flow path 50 is compressed, generating a high-temperature, high-pressure gas refrigerant. This gas refrigerant is pressure-fed to the indoor heat exchanger 12. In the indoor heat exchanger 12, heat exchange occurs between the high-temperature refrigerant and the low-temperature indoor air, and high-temperature air is supplied to the room. Meanwhile, the refrigerant loses heat and condenses, becoming a high-temperature, high-pressure liquid refrigerant. The refrigerant that passes through the indoor heat exchanger 12 flows through the switching unit 40 and the third flow path 70 into the liquid piping unit 32 of the liquid-gas heat exchanger 30. In the liquid-gas heat exchanger 30, heat exchange occurs between the low-temperature, low-pressure gas refrigerant in the gas piping unit 31 and the high-temperature, high-pressure liquid refrigerant in the liquid piping unit 32. As a result, the gas refrigerant becomes superheated. In addition, a portion of the liquid refrigerant is stored as excess in the storage space 33.

[0021] The high-temperature, high-pressure liquid refrigerant flows from the third flow path 70 through the switching unit 40 toward the expansion valve 14. As the refrigerant passes through the expansion valve 14, it is decompressed, generating a low-temperature, low-pressure, two-phase gas-liquid refrigerant. This low-temperature, low-pressure, two-phase gas-liquid refrigerant is sent to the outdoor heat exchanger 15. In the outdoor heat exchanger 15, heat exchange occurs between the refrigerant and the outdoor air. As a result, the refrigerant becomes a low-temperature, low-pressure gas. The low-temperature, low-pressure gas refrigerant flows through the four-way valve 20 and the second flow path 60 into the gas piping unit 31 of the liquid-gas heat exchanger 30. In the liquid-gas heat exchanger 30, the heat exchange described above occurs, and the gas refrigerant becomes superheated. The superheated low-temperature, low-pressure gas refrigerant then returns to the compressor 11. The above cycle occurs continuously, allowing the air conditioner 1 to perform heating operation.

[0022] (Operation During Cooling Operation) Next, the operation of the air conditioner 1 during cooling operation will be described with reference to FIG. 2 . During cooling operation, the four-way valve 20 and the switching unit 40 are open as shown in FIG. 2 . The high-temperature, high-pressure gas refrigerant generated by the compressor 11 passes through the four-way valve 20 and is directed to the outdoor heat exchanger 15. In the outdoor heat exchanger 15, heat exchange occurs between the high-temperature outdoor air and the even higher-temperature refrigerant. As a result, the refrigerant loses heat and condenses, producing a high-temperature, high-pressure liquid refrigerant. The high-temperature, high-pressure liquid refrigerant passes through the expansion valve 14 and becomes a low-temperature, low-pressure, two-phase gas-liquid refrigerant. Furthermore, the low-temperature, low-pressure, two-phase gas-liquid refrigerant passes through the switching unit 40 and is directed to the indoor heat exchanger 12. In the indoor heat exchanger 12, heat exchange occurs between the low-temperature refrigerant and the high-temperature indoor air. As a result, cool air is supplied to the room, and the refrigerant vaporizes, producing a low-temperature, low-pressure gas refrigerant. This refrigerant passes through the four-way valve 20, passes through the second flow path 60, and flows into the gas piping section 31 of the liquid-gas heat exchanger 30. Unlike during heating operation, heat exchange with other refrigerants does not occur in the liquid-gas heat exchanger 30. The low-temperature, low-pressure gas refrigerant that has passed through the liquid-gas heat exchanger 30 returns to the compressor 11. The above cycle occurs continuously, allowing the air conditioner 1 to perform cooling operation.

[0023] (Operation and Effect) Generally, a receiver capable of temporarily storing refrigerant is provided in the flow path of the refrigeration cycle 10 of an air conditioner. The amount of refrigerant supplied to the circuit is adjusted by this receiver. The liquid-gas heat exchanger 30 described above, which exchanges heat between gas refrigerant and liquid refrigerant to improve performance, is also used.

[0024] However, when the receiver and the liquid-gas heat exchanger 30 are provided separately, the internal volume of the piping of the refrigeration cycle 10 (the total volume of the flow path through which the refrigerant passes) increases, making it necessary to increase the amount of refrigerant to be enclosed. This is because the piping needs to be constantly filled with refrigerant. Therefore, there has been a growing demand for an air conditioner 1 that uses a liquid-gas heat exchanger 30 but requires a reduced amount of refrigerant. Therefore, the present embodiment employs the above-described configurations.

[0025] According to the above configuration, the liquid-gas heat exchanger 30 is provided with a storage space 33 capable of storing liquid refrigerant. As a result, if the amount of refrigerant is excessive during cooling or heating operation, the excess refrigerant can be stored in the storage space 33. In other words, the liquid-gas heat exchanger 30 also functions as a receiver. This reduces the overall amount of refrigerant used. As a result, the total length of the refrigerant piping is reduced, and the capacity of each device is also reduced, allowing for significant reductions in the manufacturing and maintenance costs of the air conditioner 1.

[0026] It is known that an excess amount of refrigerant may occur during heating operation if the internal volume of the piping of the outdoor heat exchanger 15 is larger than the internal volume of the piping of the indoor heat exchanger 12, or if the refrigerant pressure in the indoor heat exchanger 12 is relatively high during heating operation. With the above configuration, if an excessive amount of refrigerant is present during heating operation, the excess refrigerant can be stored in the storage space 33. In other words, the liquid-gas heat exchanger 30 also functions as a receiver. This reduces the overall amount of refrigerant used. Furthermore, since liquid refrigerant does not flow into the liquid-gas heat exchanger 30 during cooling, the amount of refrigerant can be further reduced.

[0027] With the above configuration, heat exchange can be performed between the gas refrigerant flowing through the gas piping portion 31 and the liquid refrigerant flowing through the liquid piping portion 32, and excess liquid refrigerant can be stored in the storage space 33. In other words, it is possible to achieve both the functions of a receiver and a liquid-gas heat exchanger 30. This reduces the overall amount of refrigerant used. As a result, the total length of the refrigerant piping is reduced, and the capacity of each device is also reduced, making it possible to significantly reduce the manufacturing and maintenance costs of the air conditioner 1.

[0028] The first embodiment of the present disclosure has been described above. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure.

[0029] Second Embodiment Next, a second embodiment of the present disclosure will be described with reference to Fig. 3 and Fig. 4. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0030] In this embodiment, the refrigerant amount is set to generate excess refrigerant during cooling operation, which is the opposite of the first embodiment. Furthermore, the position of the expansion valve 14 differs from that of the first embodiment. Specifically, as shown in FIG. 3 , the expansion valve 14 is provided in the first flow path 50 between the indoor heat exchanger 12 and the switching unit 40.

[0031] (Operation During Heating Operation) FIG. 3 shows the flow of refrigerant during heating operation. The high-temperature, high-pressure gas refrigerant generated by the compressor 11 flows through the four-way valve 20 toward the indoor heat exchanger 12. In the indoor heat exchanger 12, heat exchange occurs between the low-temperature indoor air and the high-temperature refrigerant. As a result, high-temperature air is supplied to the room. Meanwhile, the refrigerant loses heat and condenses, becoming a high-temperature, high-pressure liquid refrigerant. The refrigerant that has passed through the indoor heat exchanger 12 passes through the expansion valve 14, becoming a low-temperature, low-pressure, two-phase gas-liquid refrigerant. The low-temperature, low-pressure, two-phase gas-liquid refrigerant flows through the switching unit 40 and into the outdoor heat exchanger 15. In the outdoor heat exchanger 15, heat exchange occurs between the low-temperature outdoor air and an even lower-temperature refrigerant. As a result, the refrigerant vaporizes and becomes a low-temperature, low-pressure gas refrigerant. This gas refrigerant returns to the compressor 11 via the four-way valve 20 and the liquid-gas heat exchanger 30. At this time, no liquid refrigerant flows in the liquid piping section 32 of the liquid-gas heat exchanger 30, and therefore no heat exchange occurs between the liquid refrigerant and the gas refrigerant. The above cycle occurs continuously, and the air conditioner 1 performs heating operation.

[0032] (Operation During Cooling Operation) Next, with reference to FIG. 4 , the operation during cooling operation will be described. The high-temperature, high-pressure gas refrigerant generated by the compressor 11 flows toward the outdoor heat exchanger 15. In the outdoor heat exchanger 15, heat exchange occurs between the low-temperature outdoor air and the high-temperature refrigerant. As a result, the refrigerant loses heat and condenses, generating a high-temperature, high-pressure liquid refrigerant. This refrigerant flows through the switching unit 40 and into the liquid piping unit 32 of the liquid-gas heat exchanger 30. In the liquid-gas heat exchanger 30, heat exchange occurs with the gas refrigerant flowing through the gas piping unit 31. As a result, the gas refrigerant becomes superheated. A portion of the liquid refrigerant that flows into the liquid piping unit 32 is stored in the storage space 33 as a surplus. The liquid refrigerant then flows through the switching unit 40 and toward the expansion valve 14. By passing through the expansion valve 14, it becomes a low-temperature gas-liquid two-phase refrigerant. This low-temperature refrigerant exchanges heat with the high-temperature indoor air in the indoor heat exchanger 12. As a result, cool air is supplied to the room. The gas-liquid two-phase refrigerant vaporizes through heat exchange, becoming a low-temperature, low-pressure gas refrigerant. This gas refrigerant passes through the four-way valve 20 and heads to the liquid-gas heat exchanger 30, where it becomes superheated through heat exchange with the liquid refrigerant. The gas refrigerant then returns to the compressor 11. The above cycle occurs continuously, allowing the air conditioner 1 to perform cooling operation.

[0033] (Effects) It is known that an excess amount of refrigerant may occur during cooling operation if the piping volume of the indoor heat exchanger 12 is larger than the piping volume of the outdoor heat exchanger 15, or if the refrigerant pressure in the outdoor heat exchanger 15 is relatively high during cooling operation. With the above configuration, if an excessive amount of refrigerant is present during cooling operation, the excess refrigerant can be stored in the storage space 33. In other words, the liquid-gas heat exchanger 30 also functions as a receiver. This reduces the overall amount of refrigerant used. It also reduces the total length of the piping through which the refrigerant flows. As a result, the manufacturing and maintenance costs of the air conditioner 1 can be significantly reduced. Furthermore, because liquid refrigerant does not flow into the liquid-gas heat exchanger 30 during heating, the amount of refrigerant used can be further reduced.

[0034] The second embodiment of the present disclosure has been described above. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure.

[0035] Third Embodiment Next, a third embodiment of the present disclosure will be described with reference to Fig. 5 and Fig. 6. Note that the same components as those in the above embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0036] In this embodiment, it is assumed that excess refrigerant is generated during both heating operation and cooling operation. In addition to the expansion valve 14 between the switching unit 40 and the outdoor heat exchanger 15 described in the first embodiment, another expansion valve is provided between the indoor heat exchanger 12 and the switching unit 40. This other expansion valve will be referred to as a second expansion valve 114 hereinafter.

[0037] (Operation During Heating Operation) FIG. 5 shows the refrigerant flow during heating operation. The high-temperature, high-pressure gas refrigerant generated by the compressor 11 passes through the four-way valve 20 and heads toward the indoor heat exchanger 12. In the indoor heat exchanger 12, heat exchange occurs between the low-temperature indoor air and the high-temperature refrigerant. The indoor air is heated, and the refrigerant loses heat and condenses, becoming a high-temperature, high-pressure liquid refrigerant. This liquid refrigerant passes through the second expansion valve 114, but is not depressurized by the second expansion valve 114 during heating operation. The liquid refrigerant then passes through the switching unit 40 and heads toward the liquid piping unit 32 of the liquid-gas heat exchanger 30. In the liquid-gas heat exchanger 30, heat exchange occurs between the liquid refrigerant and the gas refrigerant, superheating the gas refrigerant. A portion of the liquid refrigerant is stored as excess in the storage space 33. The remaining liquid refrigerant passes through the switching unit 40 and heads toward the expansion valve 14. By passing through the expansion valve 14, a low-temperature, low-pressure, two-phase gas-liquid refrigerant is generated. This gas-liquid two-phase refrigerant exchanges heat with outdoor air in the outdoor heat exchanger 15. As a result, the refrigerant vaporizes and becomes a low-temperature, low-pressure gas refrigerant. The low-temperature, low-pressure gas refrigerant flows through the four-way valve 20 and the second flow path 60 into the gas piping section 31 of the liquid-gas heat exchanger 30. In the liquid-gas heat exchanger 30, the heat exchange described above occurs, and the gas refrigerant becomes superheated. The superheated low-temperature, low-pressure gas refrigerant then returns to the compressor 11. The above cycle occurs continuously, allowing the air conditioner 1 to perform heating operation.

[0038] Next, the operation during cooling operation will be described with reference to FIG. 6 . The high-temperature, high-pressure gas refrigerant generated by the compressor 11 flows toward the outdoor heat exchanger 15. In the outdoor heat exchanger 15, heat exchange occurs between the low-temperature outdoor air and the high-temperature refrigerant. As a result, the refrigerant loses heat and condenses, producing a high-temperature, high-pressure liquid refrigerant. The liquid refrigerant passes through the expansion valve 14, but is not depressurized by the expansion valve 14 during cooling operation. The refrigerant then flows through the switching unit 40 into the liquid piping unit 32 of the liquid-gas heat exchanger 30. In the liquid-gas heat exchanger 30, heat exchange occurs between the refrigerant and the gas refrigerant flowing through the gas piping unit 31. As a result, the gas refrigerant becomes superheated. A portion of the liquid refrigerant that flows into the liquid piping unit 32 is stored as excess in the storage space 33. The liquid refrigerant then flows through the switching unit 40 toward the second expansion valve 114. By passing through the second expansion valve 114, it becomes a lower-temperature two-phase gas-liquid refrigerant. This low-temperature refrigerant exchanges heat with the high-temperature indoor air in the indoor heat exchanger 12, thereby supplying cool air into the room. The gas-liquid two-phase refrigerant is vaporized through heat exchange, becoming a low-temperature, low-pressure gas refrigerant. This gas refrigerant passes through the four-way valve 20 and heads to the liquid-gas heat exchanger 30, where it becomes superheated through heat exchange with the liquid refrigerant. The gas refrigerant then returns to the compressor 11. The above cycle occurs continuously, allowing the air conditioner 1 to perform cooling operation.

[0039] (Effects) According to the above configuration, since another expansion valve, the second expansion valve 114, is provided between the switching unit 40 and the indoor heat exchanger 12, the internal volume of the refrigerant piping can be reduced by controlling the switching unit 40 to circulate excess liquid refrigerant through the liquid-gas heat exchanger 30 when the refrigerant is excessive, and conversely, to prevent refrigerant from circulating through the third flow path 70 when the refrigerant is insufficient, regardless of whether the operation is cooling or heating. This allows the refrigerant amount to be maintained at an appropriate level regardless of the operating state, while reducing the amount of refrigerant charged. Furthermore, the gas refrigerant can be superheated by the liquid-gas heat exchanger 30 regardless of whether the operation is cooling or heating. This further improves the performance of the air conditioner 1.

[0040] (Other Embodiments) Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like within the scope that does not deviate from the gist of the present disclosure are also included.

[0041] For example, a configuration shown in FIG. 8 can be employed as a modified example of the liquid-gas heat exchanger 30. In the example shown in FIG. 8, the liquid piping section 32 surrounds the gas piping section 31 from the outside in a double-pipe configuration. This allows liquid refrigerant to flow through the liquid piping section 32, which is also connected to the storage space 33. With this configuration, the liquid piping section 32 surrounds the gas piping section 31 from the outside in a double-pipe configuration, reducing the cross-sectional area of ​​the liquid piping section 32 and increasing the flow rate of the liquid refrigerant. This further improves the heat exchange efficiency between the liquid refrigerant and the gas refrigerant. As a result, the performance of the air conditioner 1 can be further improved.

[0042] <Additional Notes> The air conditioner 1 described in each embodiment can be understood, for example, as follows.

[0043] (1) The air conditioner 1 according to the first aspect comprises a refrigeration cycle 10 having an outdoor heat exchanger 15, an indoor heat exchanger 12, a compressor 11, and an expansion valve 14 through which a refrigerant flows sequentially, a four-way valve 20 that enables heating operation and cooling operation by switching the direction of refrigerant flow, a liquid-gas heat exchanger 30 that is capable of exchanging heat between a gas refrigerant on a low pressure side and a liquid refrigerant on a high pressure side, and a switching unit 40 that directs liquid refrigerant to the liquid-gas heat exchanger 30 in either the heating operation or the cooling operation, and the liquid-gas heat exchanger 30 has a storage space 33 in which the circulating liquid refrigerant is stored.

[0044] According to the above configuration, the liquid-gas heat exchanger 30 is provided with the storage space 33 capable of storing liquid refrigerant. As a result, if the amount of refrigerant is excessive during cooling or heating operation, the excess refrigerant can be stored in the storage space 33. This reduces the total length of the refrigerant piping compared to when the receiver and liquid-gas heat exchanger are provided separately, and reduces the overall amount of refrigerant used.

[0045] (2) The air conditioner 1 according to the second aspect is the air conditioner 1 of (1), in which, when the refrigerant becomes excessive during the heating operation, the switching unit 40 directs liquid refrigerant to the liquid-gas heat exchanger 30 only during the heating operation out of the heating operation and the cooling operation.

[0046] It is known that an excess amount of refrigerant may occur during heating operation if the internal volume of the piping of the outdoor heat exchanger 15 is larger than the internal volume of the piping of the indoor heat exchanger 12, or if the refrigerant pressure in the indoor heat exchanger 12 is relatively high during heating operation. With the above configuration, if an excessive amount of refrigerant is present during heating operation, the excess refrigerant can be stored in the storage space 33. On the other hand, during cooling operation, liquid refrigerant does not flow through the liquid-gas heat exchanger 30, reducing the amount of refrigerant required during cooling operation. This reduces the overall amount of refrigerant used.

[0047] (3) The air conditioner 1 according to the third aspect is the air conditioner 1 of (1), in which, when the refrigerant becomes excessive during the cooling operation, the switching unit 40 directs liquid refrigerant to the liquid-gas heat exchanger 30 only during the cooling operation of the heating operation and the cooling operation.

[0048] It is known that an excess amount of refrigerant may occur during cooling operation if the piping volume of the indoor heat exchanger 12 is larger than the piping volume of the outdoor heat exchanger 15, or if the refrigerant pressure in the outdoor heat exchanger 15 is relatively high during cooling operation. With the above configuration, if an excessive amount of refrigerant is present during cooling operation, the excess refrigerant can be stored in the storage space 33. Meanwhile, during heating operation, liquid refrigerant does not flow through the liquid-to-gas heat exchanger 30, reducing the amount of refrigerant required during heating operation. This reduces the overall amount of refrigerant used.

[0049] (4) The air conditioner 1 according to the fourth aspect comprises a refrigeration cycle 10 having an outdoor heat exchanger 15, an indoor heat exchanger 12, a compressor 11, and an expansion valve 14 through which a refrigerant flows sequentially, a four-way valve 20 that enables heating operation and cooling operation by switching the direction of refrigerant flow, a liquid-gas heat exchanger 30 that is capable of exchanging heat between a gas refrigerant on the low-pressure side and a liquid refrigerant on the high-pressure side, a switching unit 40 that directs liquid refrigerant to the liquid-gas heat exchanger 30 in at least one of the heating operation and the cooling operation, and another expansion valve 14 provided between the switching unit 40 and the indoor heat exchanger 12, and the liquid-gas heat exchanger 30 has a storage space 33 in which the circulating liquid refrigerant is stored.

[0050] According to the above configuration, since another expansion valve 14 is provided between the switching unit 40 and the indoor heat exchanger 12, surplus liquid refrigerant can be circulated through the liquid-gas heat exchanger 30 regardless of whether the operation is cooling or heating. This makes it possible to reduce surplus refrigerant regardless of the operating state.

[0051] (5) The air conditioner 1 according to the fifth aspect is an air conditioner 1 according to any one of aspects (1) to (4), wherein the liquid-gas heat exchanger 30 has a gas piping section 31 through which the gas refrigerant flows, and a liquid piping section 32 that covers the gas piping section 31 from the outside and forms the storage space 33 in which the liquid refrigerant can flow and be stored.

[0052] According to the above configuration, in addition to being able to perform heat exchange between the gas refrigerant flowing through the gas piping section 31 and the liquid refrigerant flowing through the liquid piping section 32, excess liquid refrigerant can be stored in the storage space 33.

[0053] (6) The air conditioner 1 according to a second aspect is an air conditioner 1 according to any one of aspects (1) to (4), and the liquid-gas heat exchanger 30 has a gas piping section 31 through which the gas refrigerant flows, and a liquid piping section 32 that covers the gas piping section 31 from the outside in a double-tube shape, allowing the liquid refrigerant to flow through and communicating with the storage space 33 in which the liquid refrigerant is stored.

[0054] According to the above configuration, heat can be exchanged between the gas refrigerant flowing through the gas piping portion 31 and the liquid refrigerant flowing through the liquid piping portion 32, and excess liquid refrigerant can be stored in the storage space 33. In other words, it is possible to achieve both the functions of a receiver and a liquid-gas heat exchanger 30. Furthermore, because the liquid piping portion 32 covers the gas piping portion 31 from the outside in a double-pipe shape, the flow rate of the liquid refrigerant increases. This can further improve the heat exchange efficiency between the liquid refrigerant and the gas refrigerant.

[0055] According to the present disclosure, it is possible to provide an air conditioner that uses a liquid-gas heat exchanger but reduces the amount of refrigerant used.

[0056] REFRIGERATION CYCLE 1 AIR CONDITIONER 10 REFRIGERATION CYCLE 11 COMPRESSOR 12 INDOOR HEAT EXCHANGER 13 INDOOR FAN 14 EXPANSION VALVE 15 OUTDOOR HEAT EXCHANGER 16 OUTDOOR FAN 20 FOUR-WAY VALVE 30 LIQUID-GAS HEAT EXCHANGER 31 GAS PIPING SECTION 32 LIQUID PIPING SECTION 33 STORAGE SPACE 40 SWITCHING SECTION 50 FIRST FLOW PATH 60 SECOND FLOW PATH 70 THIRD FLOW PATH 114 SECOND EXPANSION VALVE

Claims

1. An air conditioner comprising: a refrigeration cycle having an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve, through which a refrigerant flows in sequence; a four-way valve that enables heating operation and cooling operation by switching the direction of refrigerant flow; a liquid-gas heat exchanger that is capable of exchanging heat between gas refrigerant on a low pressure side and liquid refrigerant on a high pressure side; and a switching unit that directs the liquid refrigerant to the liquid-gas heat exchanger in either the heating operation or the cooling operation, wherein the liquid-gas heat exchanger has a storage space in which the circulating liquid refrigerant is stored.

2. An air conditioner as described in claim 1, wherein when the refrigerant becomes excessive during the heating operation, the switching unit directs the liquid refrigerant to the liquid-gas heat exchanger only during the heating operation out of the heating operation and the cooling operation.

3. An air conditioner as described in claim 1, wherein when the refrigerant becomes excessive during the cooling operation, the switching unit directs the liquid refrigerant to the liquid-gas heat exchanger only during the cooling operation among the heating operation and the cooling operation.

4. An air conditioner comprising: a refrigeration cycle having an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve, through which a refrigerant flows in sequence; a four-way valve that enables heating operation and cooling operation by switching the direction of refrigerant flow; a liquid-gas heat exchanger that is capable of exchanging heat between a gas refrigerant on a low pressure side and a liquid refrigerant on a high pressure side; a switching unit that directs the liquid refrigerant to the liquid-gas heat exchanger in at least one of the heating operation and the cooling operation; and another expansion valve that is provided between the switching unit and the indoor heat exchanger, wherein the liquid-gas heat exchanger has a storage space in which the circulating liquid refrigerant is stored.

5. An air conditioner as described in any one of claims 1 to 4, wherein the liquid-gas heat exchanger has: a gas piping section through which the gas refrigerant flows; and a liquid piping section that covers the gas piping section from the outside and forms the storage space through which the liquid refrigerant can flow and in which it can be stored.

6. An air conditioner as described in any one of claims 1 to 4, wherein the liquid-gas heat exchanger has: a gas piping section through which the gas refrigerant flows; and a liquid piping section that covers the gas piping section from the outside in a double-tube shape, thereby allowing the liquid refrigerant to flow and that is connected to the storage space in which the liquid refrigerant is stored.

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