Air conditioner

Abstract

To provide an air conditioner in which a refrigerant amount is reduced while using a liquid-gas heat exchanger.SOLUTION: An air conditioner comprises: a refrigeration cycle having an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve, through which a refrigerant circulates sequentially; a four-way valve that enables heating and cooling operations by switching a circulation direction of the refrigerant; a liquid-gas heat exchanger that can exchange heat between a gas refrigerant on a low pressure side and a liquid refrigerant on a high pressure side; and a switching unit that guides the liquid refrigerant to the liquid-gas heat exchanger in either the heating operation or the cooling operation. The liquid-gas heat exchanger has a storage space in which the circulating liquid refrigerant is stored.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an air conditioner. [Background technology]

[0002] Generally, a receiver capable of temporarily storing refrigerant is provided in the flow path of the refrigeration cycle of an air conditioner. The amount of refrigerant supplied to the circuit is adjusted by this receiver (see Patent Document 1 below). In addition, a liquid-gas heat exchanger is known that exchanges heat between gas refrigerant and liquid refrigerant to improve performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-159587 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the receiver and the liquid-gas heat exchanger are provided separately, the internal volume of the piping of the refrigeration cycle (the total volume of the flow path through which the refrigerant passes) becomes large, and it becomes necessary to increase the amount of refrigerant to be enclosed. This is because the inside of the piping needs to be constantly filled with refrigerant. Therefore, there has been a growing demand for air conditioners that use a liquid-gas heat exchanger but reduce the amount of refrigerant.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide an air conditioner in which the amount of refrigerant is reduced while using a liquid-gas heat exchanger. [Means for solving the problem]

[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 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 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 is capable of exchanging 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 that is 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. Effect of the Invention

[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. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a circuit diagram of the air conditioner according to the first embodiment of the present disclosure, illustrating a state during heating operation. [Diagram 2] FIG. 1 is a circuit diagram of an air conditioner according to a first embodiment of the present disclosure, illustrating a state during cooling operation. [Diagram 3] FIG. 11 is a circuit diagram of an air conditioner according to a second embodiment of the present disclosure, illustrating a state during heating operation. [Figure 4] FIG. 11 is a circuit diagram of an air conditioner according to a second embodiment of the present disclosure, illustrating a state during cooling operation. [Diagram 5] FIG. 11 is a circuit diagram of an air conditioner according to a third embodiment of the present disclosure, illustrating a state during heating operation. [Figure 6] FIG. 11 is a circuit diagram of an air conditioner according to a third embodiment of the present disclosure, illustrating a state during cooling operation. [Figure 7] FIG. 2 is a schematic diagram showing the configuration of a liquid-gas heat exchanger according to each embodiment of the present disclosure. [Figure 8] FIG. 13 is a schematic diagram illustrating a modified example of the liquid-gas heat exchanger according to each embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] First Embodiment (Configuration of Air Conditioner 1) An air conditioner 1 according to a first embodiment of the present disclosure will be described below 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-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 exchanging heat between the indoor air and the refrigerant, and between the outdoor air and the refrigerant, by compressing and expanding the refrigerant that flows through each device in sequence in the refrigeration cycle 10. Note that Fig. 1 shows the air conditioner 1 in heating operation. Below, the flow of the refrigerant and the operation of each device will be explained using the heating operation as an example, and Fig. 2 will be used to explain the flow of the refrigerant and the operation of each device during cooling operation.

[0012] (Configuration of refrigeration cycle 10) 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 passage 50 that forms an annular shape.

[0013] The compressor 11 is, for example, a scroll type or rotary type rotary machine, 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 air in the room and the refrigerant. An indoor fan 13 is provided adjacent 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, for example, a fin-and-tube type or flat tube type heat exchanger.

[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 can be adjusted by an external signal, and the refrigerant expands and its pressure decreases when the refrigerant passes through the expansion valve 14. 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 in addition to the outdoor heat exchanger 15. The outdoor fan 16 is provided to forcibly supply outdoor air toward the outdoor heat exchanger 15 and 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 an excess of refrigerant is generated during heating operation.

[0016] (Configuration of four-way valve 20) A four-way valve 20 is provided between the compressor 11 and the indoor heat exchanger 12 in the first flow path 50. 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 flow path is switched 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 leading to the liquid-gas heat exchanger 30, which will be described in detail later.

[0017] (Configuration of liquid-gas heat exchanger 30) Between one port of the four-way valve 20 and the inlet end of the compressor 11, an annular second flow passage 60 is provided. A liquid-gas heat exchanger 30 is provided on this second flow passage 60. The liquid-gas heat exchanger 30 exchanges heat between a low-temperature, low-pressure gas refrigerant flowing out from the outdoor heat exchanger 15 and a 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. A low-temperature, low-pressure gas refrigerant flows in the gas piping section 31 before being sucked into the compressor 11. The liquid piping section 32 covers the gas piping section 31 from the outside. A liquid refrigerant flows in the liquid piping section 32 from a direction opposite to the refrigerant flowing in 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 required. In other words, the storage space 33 has a function of a conventional receiver.

[0018] (Configuration of Switching Unit 40) Between the indoor heat exchanger 12 and the expansion valve 14 on the first flow path 50, another four-way valve 20 is provided as a switching unit 40. 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 of the air conditioner 1 during heating operation will be described with reference to Fig. 1. Note that solid arrows in Fig. 1 to Fig. 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 to generate 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. On the other hand, the refrigerant is deprived of heat and condensed to become a high-temperature, high-pressure liquid refrigerant. The refrigerant that has passed 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 in the storage space 33 as a surplus.

[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. The refrigerant is decompressed by passing through the expansion valve 14, and a low-temperature, low-pressure, two-phase gas-liquid refrigerant is generated. 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 above-mentioned heat exchange 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, and the air conditioner 1 performs 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 heads toward 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, generating a high-temperature, high-pressure liquid refrigerant. The high-temperature, high-pressure liquid refrigerant passes through the expansion valve 14, becoming a low-temperature, low-pressure two-phase gas-liquid liquid refrigerant. Furthermore, the low-temperature, low-pressure two-phase gas-liquid liquid refrigerant passes through the switching unit 40 and heads toward 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 is vaporized to generate 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, thereby performing cooling operation by the air conditioner 1.

[0023] (Action and effect) Generally, a receiver capable of temporarily storing refrigerant is provided in the flow path of the refrigeration cycle 10 of the air conditioner. The amount of refrigerant supplied to the circuit is adjusted by this receiver. In addition, the above-mentioned liquid-gas heat exchanger 30, 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) becomes large, and it becomes necessary to increase the amount of refrigerant to be enclosed. This is because the inside of the piping needs to be constantly filled with refrigerant. Thus, there has been an increasing demand for an air conditioner 1 that uses a liquid-gas heat exchanger 30 but with a reduced amount of refrigerant. Therefore, in this embodiment, the above-mentioned configurations are adopted.

[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, when the amount of refrigerant is excessive during cooling or heating operation, it is possible to store the excess refrigerant in the storage space 33. In other words, the liquid-gas heat exchanger 30 also functions as a receiver. This makes it possible to reduce 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 costs and maintenance costs of the air conditioner 1.

[0026] Here, it is known that when the piping internal volume of the outdoor heat exchanger 15 is larger than the piping internal volume of the indoor heat exchanger 12, or when the operating conditions are such that the refrigerant pressure in the indoor heat exchanger 12 during heating operation is relatively high, the amount of refrigerant becomes excessive during heating operation. According to the above configuration, when the amount of refrigerant is excessive during heating operation, it is possible to store the excess refrigerant in the storage space 33. In other words, the liquid-gas heat exchanger 30 also functions as a receiver. This makes it possible to reduce the overall amount of refrigerant used. In addition, since liquid refrigerant does not flow into the liquid-gas heat exchanger 30 during cooling, the amount of refrigerant can be further reduced.

[0027] According to the above configuration, in addition to being able to exchange heat 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. In other words, it is possible to achieve both the functions of the receiver and the liquid-gas heat exchanger 30. This makes it possible to reduce 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 costs 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 Figures 3 and 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, contrary to the first embodiment, a case will be described in which the refrigerant amount is set so that excess refrigerant occurs during cooling operation. Also, in this embodiment, the position at which the expansion valve 14 is provided is different from that in the first embodiment. Specifically, as shown in FIG. 3, the expansion valve 14 is provided on 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 the refrigerant 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. As a result, high-temperature air is supplied to the room. On the other hand, the refrigerant is deprived of heat and condenses to become a high-temperature, high-pressure liquid refrigerant. The refrigerant that has passed through the indoor heat exchanger 12 passes through the expansion valve 14 to become a low-temperature, low-pressure two-phase gas-liquid liquid refrigerant. The low-temperature, low-pressure two-phase gas-liquid liquid refrigerant flows through the switching unit 40 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 through the four-way valve 20 and the liquid-gas heat exchanger 30. At this time, no heat exchange occurs between the liquid refrigerant and the gas refrigerant because no liquid refrigerant flows in the liquid piping section 32 of the liquid-gas heat exchanger 30. The above cycle occurs continuously, thereby performing heating operation by the air conditioner 1.

[0032] (Operation during cooling operation) Next, referring to FIG. 4, the operation during cooling operation will be described. The high-temperature, high-pressure gas refrigerant generated by the compressor 11 is directed to 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, and 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 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 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, cold air is supplied to the room. The gas-liquid two-phase refrigerant is vaporized by heat exchange, becoming a low-temperature, low-pressure gas refrigerant. This gas refrigerant passes through the four-way valve 20 and flows to the liquid-gas heat exchanger 30, where it becomes superheated by heat exchange with the liquid refrigerant described above. The gas refrigerant then returns to the compressor 11. The above cycle occurs continuously, allowing the air conditioner 1 to perform cooling operation.

[0033] (Action and effect) Here, it is known that when the piping volume of the indoor heat exchanger 12 is larger than the piping volume of the outdoor heat exchanger 15, or when the operating conditions are such that the refrigerant pressure in the outdoor heat exchanger 15 during cooling operation is relatively high, the amount of refrigerant becomes excessive during cooling operation. According to the above configuration, when the amount of refrigerant is excessive during cooling operation, it is possible to store the excess refrigerant in the storage space 33. In other words, the liquid-gas heat exchanger 30 also functions as a receiver. This makes it possible to reduce the overall amount of refrigerant used. In addition, the total length of the piping through which the refrigerant flows can also be reduced. As a result, it is possible to significantly reduce the manufacturing cost and maintenance cost of the air conditioner 1. In addition, since liquid refrigerant does not flow into the liquid-gas heat exchanger 30 during heating, the amount of refrigerant 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-described embodiments are given 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 and cooling operations. 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. The other expansion valve is hereinafter referred to as a second expansion valve 114.

[0037] (Operation during heating operation) FIG. 5 shows the flow of the refrigerant 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 is deprived of heat and condensed, 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, and the gas refrigerant becomes superheated. In addition, a portion of the liquid refrigerant is stored in the storage space 33 as a surplus. 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 gas-liquid two-phase 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 into the gas piping section 31 of the liquid-gas heat exchanger 30 via the four-way valve 20 and the second flow path 60. In the liquid-gas heat exchanger 30, the above-mentioned heat exchange 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 is directed to 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, and as a result, the refrigerant is deprived of heat and condensed, generating 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. Then, this refrigerant passes through the switching unit 40 and flows 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 in the storage space 33 as a surplus. Then, the liquid refrigerant passes through the switching unit 40 and heads toward the second expansion valve 114. By passing through the second expansion valve 114, it becomes a gas-liquid two-phase refrigerant with an even lower temperature. 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 is vaporized by 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 by heat exchange with the liquid refrigerant described above. The gas refrigerant then returns to the compressor 11. The above cycle occurs continuously, allowing the air conditioner 1 to perform cooling operation.

[0039] (Action and effect) According to the above configuration, since the second expansion valve 114, which is another expansion valve, is provided between the switching unit 40 and the indoor heat exchanger 12, regardless of whether the operation is cooling or heating, the switching unit 40 is controlled so that when the refrigerant is excessive, the surplus liquid refrigerant is circulated through the liquid-gas heat exchanger 30, and conversely, when the refrigerant is insufficient, the refrigerant piping volume can be reduced by not circulating through the third flow path 70. This makes it possible to maintain an appropriate amount of refrigerant regardless of the operating state and reduce the amount of refrigerant charged. In addition, regardless of whether the operation is cooling or heating, the gas refrigerant can be superheated by the liquid-gas heat exchanger 30. This makes it possible to further improve 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 that do not depart from the gist of the present disclosure are also included.

[0041] For example, as a modified example of the liquid-gas heat exchanger 30, the configuration shown in FIG. 8 can be adopted. In the example shown in the figure, the liquid piping section 32 covers the gas piping section 31 from the outside in a double-tube shape. This allows the liquid refrigerant to flow through the liquid piping section 32, which is also connected to the storage space 33. According to this configuration, since the liquid piping section 32 covers the gas piping section 31 from the outside in a double-tube shape, the flow path cross-sectional area of ​​the liquid piping section 32 is reduced, and the flow rate of the liquid refrigerant increases. This can further improve 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 of 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 in sequence, a four-way valve 20 that enables heating operation and cooling operation by switching the flow direction of the refrigerant, 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 guides 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, when the amount of refrigerant is excessive during cooling operation or heating operation, it becomes possible to store the excess refrigerant in the storage space 33. As a result, the total length of the refrigerant piping can be reduced compared to a case where the receiver and the liquid-gas heat exchanger are provided separately, and the overall amount of refrigerant used can be reduced.

[0045] (2) The air conditioner 1 according to the second aspect is the air conditioner 1 of (1), wherein 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 among the heating operation and the cooling operation.

[0046] Here, it is known that when the piping internal volume of the outdoor heat exchanger 15 is larger than the piping internal volume of the indoor heat exchanger 12, or when the operating conditions are such that the refrigerant pressure in the indoor heat exchanger 12 during heating operation is relatively high, the amount of refrigerant becomes excessive during heating operation. With the above configuration, when the amount of refrigerant is excessive during heating operation, it is possible to store the excess refrigerant in the storage space 33. On the other hand, during cooling operation, since liquid refrigerant does not flow through the liquid-gas heat exchanger 30, it is possible to reduce the amount of refrigerant required during cooling operation. This allows the overall amount of refrigerant used to be reduced.

[0047] (3) The air conditioner 1 according to a third aspect is the air conditioner 1 of (1), wherein 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 among the heating operation and the cooling operation.

[0048] Here, it is known that when the piping volume of the indoor heat exchanger 12 is larger than the piping volume of the outdoor heat exchanger 15, or when the operating conditions are such that the refrigerant pressure in the outdoor heat exchanger 15 during cooling operation is relatively high, the amount of refrigerant becomes excessive during cooling operation. With the above configuration, when the amount of refrigerant is excessive during cooling operation, it is possible to store the excess refrigerant in the storage space 33. On the other hand, during heating operation, since liquid refrigerant does not flow through the liquid-gas heat exchanger 30, it is possible to reduce the amount of refrigerant required during heating operation. This allows the overall amount of refrigerant used to be reduced.

[0049] (4) The air conditioner 1 of 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 in sequence, a four-way valve 20 that enables heating operation and cooling operation by switching the flow direction of the refrigerant, 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, 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 the surplus refrigerant regardless of the operating state.

[0051] (5) The air conditioner 1 of the fifth aspect is an air conditioner 1 of any one of the 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 through which the liquid refrigerant can flow and be stored.

[0052] According to the above configuration, in addition to being able to exchange heat 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) An air conditioner 1 according to a second aspect is an air conditioner 1 according to any one of the 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 in a double-tube shape, thereby allowing the liquid refrigerant to flow and that is connected to the storage space 33 in which the liquid refrigerant is stored.

[0054] According to the above configuration, in addition to being able to exchange heat 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. In other words, it is possible to achieve both the functions of a receiver and a liquid-gas heat exchanger 30. In addition, since the liquid piping section 32 covers the gas piping section 31 from the outside in a double-pipe shape, the flow rate of the liquid refrigerant increases. This can further improve the efficiency of heat exchange between the liquid refrigerant and the gas refrigerant. [Explanation of symbols]

[0055] 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. A refrigeration cycle having an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve, each through which the refrigerant flows sequentially, A four-way valve that enables heating and cooling operations by switching the direction of refrigerant flow; a liquid-gas heat exchanger capable of exchanging heat between a gaseous refrigerant on the low-pressure side and a liquid refrigerant on the high-pressure side; and a switching unit that directs the liquid refrigerant to the liquid-gas heat exchanger in either the heating or cooling operation. Equipped with, The aforementioned liquid gas heat exchanger has a storage space in which the flowing liquid refrigerant is stored, In the event that the refrigerant becomes excessive during the heating operation, the switching unit directs liquid refrigerant to the liquid gas heat exchanger only during the heating operation, out of the two heating and cooling operations.

2. A refrigeration cycle having an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve, each through which the refrigerant flows sequentially, A four-way valve that enables heating and cooling operations by switching the direction of refrigerant flow; a liquid-gas heat exchanger capable of exchanging heat between a gaseous refrigerant on the low-pressure side and a liquid refrigerant on the high-pressure side; and a switching unit that directs the liquid refrigerant to the liquid-gas heat exchanger in either the heating or cooling operation. Equipped with, The aforementioned liquid gas heat exchanger has a storage space in which the flowing liquid refrigerant is stored, In the event that the amount of refrigerant becomes excessive during the cooling operation, the switching unit directs liquid refrigerant to the liquid gas heat exchanger only during the cooling operation, out of the heating and cooling operations.

3. A refrigeration cycle having an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve, each through which the refrigerant flows sequentially, A four-way valve that enables heating and cooling operations by switching the direction of refrigerant flow; a liquid-gas heat exchanger capable of exchanging heat between a gaseous refrigerant on the low-pressure side and a liquid refrigerant on the high-pressure side; and a switching unit that guides the liquid refrigerant to the liquid-gas heat exchanger in at least one of the heating and cooling operations. The other expansion valve provided between the switching unit and the indoor heat exchanger, Equipped with, The aforementioned liquid gas heat exchanger has a storage space in which the flowing liquid refrigerant is stored, In the event that the refrigerant becomes excessive during the heating operation, the switching unit directs liquid refrigerant to the liquid gas heat exchanger only during the heating operation, out of the two heating and cooling operations.

4. A refrigeration cycle having an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve, each through which the refrigerant flows sequentially, A four-way valve that enables heating and cooling operations by switching the direction of refrigerant flow; a liquid-gas heat exchanger capable of exchanging heat between a gaseous refrigerant on the low-pressure side and a liquid refrigerant on the high-pressure side; and a switching unit that guides the liquid refrigerant to the liquid-gas heat exchanger in at least one of the heating and cooling operations. The other expansion valve provided between the switching unit and the indoor heat exchanger, Equipped with, The aforementioned liquid gas heat exchanger has a storage space in which the flowing liquid refrigerant is stored, In the event that the amount of refrigerant becomes excessive during the cooling operation, the switching unit directs liquid refrigerant to the liquid gas heat exchanger only during the cooling operation, out of the heating and cooling operations.

5. The aforementioned liquid-gas heat exchanger is The gas piping section through which the aforementioned gaseous refrigerant flows, A liquid piping section that covers the gas piping section from the outside, thereby forming the storage space through which the liquid refrigerant can flow and store, An air conditioner according to any one of claims 1 to 4, having the following features.

6. The aforementioned liquid-gas heat exchanger is The gas piping section through which the aforementioned gaseous refrigerant flows, By covering the gas piping section from the outside in a double-tube shape, a liquid piping section is provided that allows the liquid refrigerant to flow and communicates with the storage space in which the liquid refrigerant is stored, An air conditioner according to any one of claims 1 to 4, having the following features.

Images