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

Technical Field

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

[0002] This application claims priority to Japanese Patent Application No. 2023-141945, filed in Japan on September 1, 2023, the contents of which are incorporated herein by reference.Background Art

[0003] In general, a receiver (liquid receiver) capable of temporarily storing a refrigerant is provided in a flow path of a refrigeration cycle of an air conditioner. The receiver regulates the amount of refrigerant supplied to a circuit (see the following PTL 1). In addition, a liquid-gas heat exchanger is known that performs heat exchange between a gas refrigerant and a liquid refrigerant to improve performance.Citation ListPatent Literature

[0004] [PTL 1] Japanese Unexamined Patent Application Publication No. H8-159587Summary of InventionTechnical Problem

[0005] However, when the receiver and the liquid-gas heat exchanger are separately provided, it is necessary to increase the amount of refrigerant charged since the internal volume of a pipe in the refrigeration cycle (the total volume of a flow path through which the refrigerant passes) increases. This is because the inside of the pipe needs to remain filled with the refrigerant. Therefore, there has been an increasing demand for an air conditioner in which the amount of refrigerant is reduced while a liquid-gas heat exchanger is used.

[0006] The present disclosure has been made in order to solve the above-described problems, and an object of the present disclosure is to provide an air conditioner in which the amount of refrigerant is reduced while a liquid-gas heat exchanger is used.Solution to Problem

[0007] In order to solve the above problems, according to the present disclosure, there is provided an air conditioner including: a refrigeration cycle including 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 switches a circulation direction of the refrigerant to enable a heating operation and a cooling operation; a liquid-gas heat exchanger that is capable of exchanging heat between a low-pressure-side gas refrigerant and a high-pressure-side liquid refrigerant; and a switching portion that guides the liquid refrigerant to the liquid-gas heat exchanger in either the heating operation or the cooling operation, in which the liquid-gas heat exchanger has a storage space in which the circulating liquid refrigerant is stored.

[0008] According to the present disclosure, there is provided an air conditioner including: a refrigeration cycle including 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 switches a circulation direction of the refrigerant to enable a heating operation and a cooling operation; a liquid-gas heat exchanger that is capable of exchanging heat between a low-pressure-side gas refrigerant and a high-pressure-side liquid refrigerant; a switching portion that guides 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 portion and the indoor heat exchanger, in which the liquid-gas heat exchanger has a storage space in which the circulating liquid refrigerant is stored.Advantageous Effects of Invention

[0009] According to the present disclosure, it is possible to provide an air conditioner in which the amount of refrigerant is reduced while a liquid-gas heat exchanger is used.Brief Description of Drawings

[0010] FIG. 1 is a circuit diagram showing a state of an air conditioner according to a first embodiment of the present disclosure during a heating operation. FIG. 2 is a circuit diagram showing a state of the air conditioner according to the first embodiment of the present disclosure during a cooling operation. FIG. 3 is a circuit diagram showing a state of an air conditioner according to a second embodiment of the present disclosure during a heating operation. FIG. 4 is a circuit diagram showing a state of the air conditioner according to the second embodiment of the present disclosure during a cooling operation. FIG. 5 is a circuit diagram showing a state of an air conditioner according to a third embodiment of the present disclosure during a heating operation. FIG. 6 is a circuit diagram showing a state of an air conditioner according to the third embodiment of the present disclosure during a cooling operation. FIG. 7 is a schematic view showing a configuration of a liquid-gas heat exchanger according to each embodiment of the present disclosure. FIG. 8 is a schematic view showing a modification example of the liquid-gas heat exchanger according to each embodiment of the present disclosure. Description of Embodiments<First Embodiment>(Configuration of Air Conditioner 1)

[0011] Hereinafter, an air conditioner 1 according to a first embodiment of the present disclosure will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the air conditioner 1 includes a refrigeration cycle 10, a four-way valve 20, a liquid-gas heat exchanger 30, a switching portion 40, a first flow path 50, a second flow path 60, and a third flow path 70.

[0012] The refrigeration cycle 10 is a circuit for compressing or expanding a refrigerant that sequentially circulates through each device of the refrigeration cycle 10 to exchange heat between indoor air and the refrigerant and between outdoor air and the refrigerant. In addition, FIG. 1 shows a state in which the air conditioner 1 is in a heating operation. Hereinafter, the flow of the refrigerant and the operation of each device during the heating operation as an example will be described, and the flow of the refrigerant and the operation of each device during a cooling operation will be described with reference to FIG. 2.(Configuration of Refrigeration Cycle 10)

[0013] As shown in FIG. 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 disposed in this order on the first flow path 50 having an annular shape.

[0014] The compressor 11 is, for example, a rotating machine of a scroll type or a rotary type and compresses the refrigerant in the first flow path 50. The indoor heat exchanger 12 is provided on the downstream side of the compressor 11 in the first flow path 50. The indoor heat exchanger 12 is disposed indoors and exchanges heat between the indoor air and the refrigerant. The indoor fan 13 is provided alongside the indoor heat exchanger 12. The indoor fan 13 is provided to forcibly supply the indoor air toward the indoor heat exchanger 12, thereby promoting heat exchange with the refrigerant. The indoor heat exchanger 12 is, for example, a heat exchanger of a fin-and-tube type, a flat-tube type, or the like.

[0015] The expansion valve 14 is provided on the downstream side 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 a signal from the outside. When the refrigerant passes through the expansion valve 14, the refrigerant expands, and the pressure of the refrigerant is reduced. The outdoor heat exchanger 15 is provided on the downstream side of the expansion valve 14 in the first flow path 50. The outdoor heat exchanger 15 is disposed outdoor and exchanges heat between the outdoor air and the refrigerant. The outdoor fan 16 is provided alongside the outdoor heat exchanger 15. The outdoor fan 16 is provided to forcibly supply the outdoor air toward the outdoor heat exchanger 15, thereby promoting heat exchange with the refrigerant. The outdoor heat exchanger 15 is, for example, a heat exchanger of a fin-and-tube type, a flat-tube type, or the like.

[0016] In addition, in the present embodiment, the amount of refrigerant is set such that an excess refrigerant is generated during the heating operation.(Configuration of Four-Way Valve 20)

[0017] The four-way valve 20 is provided between the compressor 11 and the indoor heat exchanger 12 in the first flow path 50. During the heating operation, the flow path of the four-way valve 20 is switched such that the refrigerant flows from the compressor 11 to the indoor heat exchanger 12 as shown in FIG. 1. On the other hand, during the cooling operation, the flow path of the four-way valve 20 is switched such 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 the second flow path 60 that leads to the liquid-gas heat exchanger 30, which will be described in detail below.(Configuration of Liquid-Gas Heat Exchanger 30)

[0018] The annular second flow path 60 is provided between one port of the four-way valve 20 and an inlet-side end portion of the compressor 11. The liquid-gas heat exchanger 30 is provided on the second flow path 60. The liquid-gas heat exchanger 30 performs heat exchange between a low-temperature and low-pressure gas refrigerant flowing out from the outdoor heat exchanger 15 and a high-temperature and high-pressure liquid refrigerant flowing out from the indoor heat exchanger 12. Specifically, as shown in FIG. 7, the liquid-gas heat exchanger 30 includes a gas pipe portion 31, a liquid pipe portion 32, and a storage space 33. The gas pipe portion 31 communicates with a suction side of the compressor 11. The low-temperature and low-pressure gas refrigerant before being sucked into the compressor 11 flows through the gas pipe portion 31. The liquid pipe portion 32 covers the gas pipe portion 31 from the outside. The liquid refrigerant flows through the liquid pipe portion 32 in a direction opposite to the direction in which the refrigerant flows through the gas pipe portion 31. In addition, a part of the liquid pipe portion 32 is the storage space 33, and the excess liquid refrigerant is stored in the storage space 33 as necessary. That is, the storage space 33 has the functions of the receiver according to the related art.(Configuration of Switching Portion 40)

[0019] Another four-way valve 20 is provided as the switching portion 40 between the indoor heat exchanger 12 and the expansion valve 14 on the first flow path 50. The switching portion 40 and the liquid-gas heat exchanger 30 are connected to each other by the annular third flow path 70. That is, the flow of the refrigerant toward the liquid-gas heat exchanger 30 is changed by switching the open state of the switching portion 40.(Operation During Heating Operation)

[0020] Next, the operation of the air conditioner 1 during the heating operation will be described with reference to FIG. 1. Further, in FIGS. 1 to 6, a solid arrow represents the flow of a relatively low-temperature refrigerant, and a broken arrow represents the flow of a relatively high-temperature refrigerant.

[0021] When the compressor 11 is driven, the refrigerant in the first flow path 50 is compressed, and a high-temperature and high-pressure gas refrigerant is generated. The gas refrigerant is pumped to the indoor heat exchanger 12. In the indoor heat exchanger 12, heat exchange is performed 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 is condensed to become a high-temperature and high-pressure liquid refrigerant. The refrigerant that has passed through the indoor heat exchanger 12 flows into the liquid pipe portion 32 of the liquid-gas heat exchanger 30 via the switching portion 40 and the third flow path 70. In the liquid-gas heat exchanger 30, heat exchange is performed between the low-temperature and low-pressure gas refrigerant in the gas pipe portion 31 and the high-temperature and high-pressure liquid refrigerant in the liquid pipe portion 32. Therefore, the gas refrigerant is superheated. In addition, a portion of the liquid refrigerant is stored as excess in the storage space 33.

[0022] The high-temperature and high-pressure liquid refrigerant flows from the third flow path 70 to the expansion valve 14 via the switching portion 40. The refrigerant is depressurized by passing through the expansion valve 14, and a low-temperature and low-pressure gas-liquid two-phase refrigerant is generated. The low-temperature and low-pressure gas-liquid two-phase refrigerant is sent to the outdoor heat exchanger 15. In the outdoor heat exchanger 15, heat exchange is performed between the refrigerant and the outdoor air. Therefore, the refrigerant becomes a low-temperature and low-pressure gas. The low-temperature and low-pressure gas refrigerant flows into the gas pipe portion 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-described heat exchange is performed, and the gas refrigerant is superheated. Then, the superheated low-temperature and low-pressure gas refrigerant returns to the compressor 11. The heating operation of the air conditioner 1 is performed by the continuous occurrence of the above-described cycle.(Operation During Cooling Operation)

[0023] Next, the operation of the air conditioner 1 during the cooling operation will be described with reference to FIG. 2. During the cooling operation, the open states of the four-way valve 20 and the switching portion 40 are as shown in FIG. 2. The high-temperature and high-pressure gas refrigerant generated by the compressor 11 flows toward the outdoor heat exchanger 15 via the four-way valve 20. In the outdoor heat exchanger 15, heat exchange is performed between the high-temperature outdoor air and the high-temperature refrigerant. As a result, the refrigerant is deprived of heat and is condensed, and a high-temperature and high-pressure liquid refrigerant is generated. The high-temperature and high-pressure liquid refrigerant passes through the expansion valve 14 and becomes a low-temperature and low-pressure gas-liquid two-phase liquid refrigerant. Further, the low-temperature and low-pressure gas-liquid two-phase liquid refrigerant flows toward the indoor heat exchanger 12 via the switching portion 40. In the indoor heat exchanger 12, heat exchange is performed between the low-temperature refrigerant and the high-temperature indoor air. Therefore, cold air is supplied to the room. In addition, the refrigerant evaporates, and a low-temperature and low-pressure gas refrigerant is generated. The refrigerant passes through the four-way valve 20 and flows into the gas pipe portion 31 of the liquid-gas heat exchanger 30 through the second flow path 60. In the liquid-gas heat exchanger 30, heat exchange with another refrigerant is not performed unlike during the heating operation. The low-temperature and low-pressure gas refrigerant that has passed through the liquid-gas heat exchanger 30 returns to the compressor 11. The cooling operation of the air conditioner 1 is performed by the continuous occurrence of the above-described cycle.(Operation and Effect)

[0024] Here, in general, a receiver (liquid receiver) capable of temporarily storing the refrigerant is provided on the flow path of the refrigeration cycle 10 of the air conditioner. The amount of refrigerant supplied to the circuit is regulated by the receiver. In addition, the liquid-gas heat exchanger 30 that performs heat exchange between the gas refrigerant and the liquid refrigerant to improve performance is also used in combination.

[0025] However, when the receiver and the liquid-gas heat exchanger 30 are separately provided, the internal volume of the pipe in the refrigeration cycle 10 (the total volume of the flow path through which the refrigerant passes) increases. Therefore, it is necessary to increase the amount of refrigerant charged. This is because the inside of the pipe needs to remain filled with the refrigerant. Therefore, there has been an increasing demand for the air conditioner 1 in which the amount of refrigerant is reduced while the liquid-gas heat exchanger 30 is used. Therefore, in the present embodiment, each of the above-described configurations is adopted.

[0026] According to the above-described configuration, the storage space 33 capable of storing the liquid refrigerant is provided in the liquid-gas heat exchanger 30. Therefore, when the amount of refrigerant is excessive during the cooling operation or the heating operation, it is possible to store the excess refrigerant in the storage space 33. That is, the liquid-gas heat exchanger 30 also has the functions of the receiver. This makes it possible to reduce the overall amount of refrigerant used. As a result, the total length of the refrigerant pipe is reduced, and the capacity of each device is reduced, which makes it possible to significantly reduce the manufacturing costs and maintenance costs of the air conditioner 1.

[0027] Here, it is known that the amount of refrigerant during the heating operation is excessive when the internal volume of the pipe in the outdoor heat exchanger 15 is larger than the internal volume of the pipe in the indoor heat exchanger 12 or in the case of an operating condition in which the refrigerant pressure in the indoor heat exchanger 12 during the heating operation is relatively high. According to the above-described configuration, when the amount of refrigerant is excessive during the heating operation, it is possible to store the excess refrigerant in the storage space 33. That is, the liquid-gas heat exchanger 30 also has the functions of the receiver. This makes it possible to reduce the overall amount of refrigerant used. In addition, since the liquid refrigerant does not flow into the liquid-gas heat exchanger 30 during cooling, it is possible to further reduce the amount of refrigerant.

[0028] According to the above-described configuration, it is possible to store the excess liquid refrigerant in the storage space 33, in addition to enabling heat exchange between the gas refrigerant flowing through the gas pipe portion 31 and the liquid refrigerant flowing through the liquid pipe portion 32. That is, it is possible to achieve both the functions of the receiver and the functions of 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 pipe is reduced, and the capacity of each device is reduced, which makes it possible to significantly reduce the manufacturing costs and maintenance costs of the air conditioner 1.

[0029] The first embodiment of the present disclosure has been described above. In addition, the above-described configuration can be changed or modified in various manners without departing from the gist of the present disclosure.<Second Embodiment>

[0030] Next, a second embodiment of the present disclosure will be described with reference to FIGS. 3 and 4. In addition, the same configurations as those in the first embodiment are denoted by the same reference numerals, and a detailed description thereof will be omitted.

[0031] In the present embodiment, unlike the first embodiment, the following description assumes that the amount of refrigerant is set such that an excess refrigerant is generated during the cooling operation. In addition, in the present embodiment, the position where 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 between the indoor heat exchanger 12 and the switching portion 40 on the first flow path 50.(Operation During Heating Operation)

[0032] FIG. 3 shows the flow of the refrigerant during the heating operation. The high-temperature and high-pressure gas refrigerant generated by the compressor 11 flows toward the indoor heat exchanger 12 via the four-way valve 20. In the indoor heat exchanger 12, heat exchange is performed between the low-temperature indoor air and the high-temperature refrigerant. In this way, high-temperature air is supplied to the room. On the other hand, the refrigerant is deprived of heat and is condensed to become a high-temperature and high-pressure liquid refrigerant. The refrigerant that has passed through the indoor heat exchanger 12 passes through the expansion valve 14 and becomes a low-temperature and low-pressure gas-liquid two-phase liquid refrigerant. The low-temperature and low-pressure gas-liquid two-phase liquid refrigerant flows into the outdoor heat exchanger 15 via the switching portion 40. In the outdoor heat exchanger 15, heat exchange is performed between the low-temperature outdoor air and the low-temperature refrigerant. Therefore, the refrigerant evaporates and becomes a low-temperature and low-pressure gas refrigerant. The gas refrigerant returns to the compressor 11 via the four-way valve 20 and the liquid-gas heat exchanger 30. Further, at this time, since the liquid refrigerant does not flow through the liquid pipe portion 32 of the liquid-gas heat exchanger 30, heat exchange between the liquid refrigerant and the gas refrigerant does not occur. The heating operation of the air conditioner 1 is performed by the continuous occurrence of the above-described cycle.(Operation During Cooling Operation)

[0033] Next, the operation during the cooling operation will be described with reference to FIG. 4. The high-temperature and 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 is deprived of heat and is condensed, and a high-temperature and high-pressure liquid refrigerant is generated. The refrigerant flows into the liquid pipe portion 32 of the liquid-gas heat exchanger 30 via the switching portion 40. In the liquid-gas heat exchanger 30, heat exchange with the gas refrigerant flowing through the gas pipe portion 31 occurs. Therefore, the gas refrigerant is superheated. A portion of the liquid refrigerant that has flowed into the liquid pipe portion 32 is stored as excess in the storage space 33. Then, the liquid refrigerant flows toward the expansion valve 14 via the switching portion 40. The liquid refrigerant passes through the expansion valve 14 and becomes a low-temperature gas-liquid two-phase refrigerant. The low-temperature refrigerant exchanges heat with the high-temperature indoor air in the indoor heat exchanger 12. In this way, cold air is supplied to the room. The gas-liquid two-phase refrigerant evaporates due to heat exchange and becomes a low-temperature and low-pressure gas refrigerant. The gas refrigerant flows toward the liquid-gas heat exchanger 30 via the four-way valve 20 and is superheated due to the heat exchange with the liquid refrigerant. Then, the gas refrigerant returns to the compressor 11. The cooling operation of the air conditioner 1 is performed by the continuous occurrence of the above-described cycle.(Operation and Effect)

[0034] Here, it is known that the amount of refrigerant during the cooling operation is excessive when the internal volume of the pipe in the indoor heat exchanger 12 is larger than the internal volume of the pipe in the outdoor heat exchanger 15 or in the case of an operating condition in which the refrigerant pressure in the outdoor heat exchanger 15 during the cooling operation is relatively high. According to the above-described configuration, when the amount of refrigerant is excessive during the cooling operation, it is possible to store the excess refrigerant in the storage space 33. That is, the liquid-gas heat exchanger 30 also has the functions of the receiver. This makes it possible to reduce the overall amount of refrigerant used. In addition, it is possible to reduce the total length of the pipe through which the refrigerant circulates. As a result, it is possible to significantly reduce the manufacturing costs and maintenance costs of the air conditioner 1. In addition, since the liquid refrigerant does not flow into the liquid-gas heat exchanger 30 during heating, it is possible to further reduce the amount of refrigerant.

[0035] The second embodiment of the present disclosure has been described above. In addition, the above-described configuration can be changed or modified in various manners without departing from the gist of the present disclosure.<Third Embodiment>

[0036] Next, a third embodiment of the present disclosure will be described with reference to FIGS. 5 and 6. In addition, the same configurations as those in each of the above-described embodiments are denoted by the same reference numerals, and a detailed description thereof will be omitted.

[0037] In the present embodiment, it is assumed that an excess refrigerant is generated during both the heating operation and the cooling operation. In addition, in the present embodiment, in addition to the expansion valve 14 between the switching portion 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 portion 40. Hereinafter, the other expansion valve is referred to as a second expansion valve 114.(Operation During Heating Operation)

[0038] FIG. 5 shows the flow of the refrigerant during the heating operation. The high-temperature and high-pressure gas refrigerant generated by the compressor 11 flows toward the indoor heat exchanger 12 via the four-way valve 20. In the indoor heat exchanger 12, heat exchange occurs between the low-temperature indoor air and the high-temperature refrigerant. The temperature of the indoor air is raised, and the refrigerant is deprived of heat and is condensed to become a high-temperature and high-pressure liquid refrigerant. The liquid refrigerant passes through the second expansion valve 114, but pressure reduction by the second expansion valve 114 is not performed during the heating operation. Then, the liquid refrigerant flows toward the liquid pipe portion 32 of the liquid-gas heat exchanger 30 via the switching portion 40. In the liquid-gas heat exchanger 30, heat exchange occurs between the liquid refrigerant and the gas refrigerant, and the gas refrigerant is superheated. In addition, a portion of the liquid refrigerant is stored as excess in the storage space 33. The remaining liquid refrigerant flows toward the expansion valve 14 via the switching portion 40. The liquid refrigerant passes through the expansion valve 14, and a low-temperature and low-pressure gas-liquid two-phase refrigerant is generated. The gas-liquid two-phase refrigerant exchanges heat with the outdoor air in the outdoor heat exchanger 15. Therefore, the refrigerant evaporates and becomes a low-temperature and low-pressure gas refrigerant. The low-temperature and low-pressure gas refrigerant flows into the gas pipe portion 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-described heat exchange is performed, and the gas refrigerant is superheated. Then, the superheated low-temperature and low-pressure gas refrigerant returns to the compressor 11. The heating operation of the air conditioner 1 is performed by the continuous occurrence of the above-described cycle.

[0039] Next, the operation during the cooling operation will be described with reference to FIG. 6. The high-temperature and 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 is deprived of heat and is condensed, and a high-temperature and high-pressure liquid refrigerant is generated. The liquid refrigerant passes through the expansion valve 14, but pressure reduction by the expansion valve 14 is not performed during the cooling operation. Then, the refrigerant flows into the liquid pipe portion 32 of the liquid-gas heat exchanger 30 via the switching portion 40. In the liquid-gas heat exchanger 30, heat exchange with the gas refrigerant flowing through the gas pipe portion 31 occurs. Therefore, the gas refrigerant is superheated. A portion of the liquid refrigerant that has flowed into the liquid pipe portion 32 is stored as excess in the storage space 33. Then, the liquid refrigerant flows toward the second expansion valve 114 via the switching portion 40. The liquid refrigerant passes through the second expansion valve 114 and becomes a low-temperature gas-liquid two-phase refrigerant. The low-temperature refrigerant exchanges heat with the high-temperature indoor air in the indoor heat exchanger 12. In this way, cold air is supplied to the room. The gas-liquid two-phase refrigerant evaporates due to heat exchange and becomes a low-temperature and low-pressure gas refrigerant. The gas refrigerant flows toward the liquid-gas heat exchanger 30 via the four-way valve 20 and is superheated due to the heat exchange with the liquid refrigerant. Then, the gas refrigerant returns to the compressor 11. The cooling operation of the air conditioner 1 is performed by the continuous occurrence of the above-described cycle.(Operation and Effect)

[0040] According to the above-described configuration, the second expansion valve 114, which is another expansion valve, is further provided between the switching portion 40 and the indoor heat exchanger 12. Therefore, when the refrigerant is excessive regardless of whether the operation is the cooling operation or the heating operation, the excess liquid refrigerant is caused to circulate through the liquid-gas heat exchanger 30. Conversely, when the refrigerant is insufficient, the switching portion 40 is controlled such that the refrigerant does not circulate through the third flow path 70. Therefore, it is possible to reduce the internal volume of the refrigerant pipe. This makes it possible to keep the amount of refrigerant at an appropriate level, regardless of the operating state, and to reduce the amount of refrigerant charged. In addition, it is possible to superheat the gas refrigerant with the liquid-gas heat exchanger 30 regardless of whether the operation is the cooling operation or the heating operation. Therefore, it is possible to further improve the performance of the air conditioner 1.(Other Embodiments)

[0041] The embodiments of the present disclosure have been described in detail above with reference to the drawings. However, the specific configuration is not limited to the embodiments, but includes design changes and the like without departing from the gist of the present disclosure.

[0042] For example, a configuration shown in FIG. 8 can be adopted as a modification example of the liquid-gas heat exchanger 30. In the example shown in FIG. 8, the liquid pipe portion 32 covers the gas pipe portion 31 in a double-pipe shape from the outside. Therefore, the liquid refrigerant can circulate through the liquid pipe portion 32, and the liquid pipe portion 32 communicates with the storage space 33. According to this configuration, since the liquid pipe portion 32 covers the gas pipe portion 31 in the double-pipe shape from the outside, the cross-sectional area of the flow path of the liquid pipe portion 32 decreases. Therefore, the flow speed of the liquid refrigerant increases. This makes it possible to further improve the efficiency of heat exchange between the liquid refrigerant and the gas refrigerant. As a result, it is possible to further improve the performance of the air conditioner 1.<Supplementary Notes>

[0043] For example, the air conditioner 1 according to each embodiment is understood as follows.

[0044] (1) An air conditioner 1 according to a first aspect includes: a refrigeration cycle 10 including an outdoor heat exchanger 15, an indoor heat exchanger 12, a compressor 11, and an expansion valve 14 through which a refrigerant circulates sequentially, a four-way valve 20 that switches a circulation direction of the refrigerant to enable a heating operation and a cooling operation, a liquid-gas heat exchanger 30 that is capable of exchanging heat between a low-pressure-side gas refrigerant and a high-pressure-side liquid refrigerant, and a switching portion 40 that guides the liquid refrigerant to the liquid-gas heat exchanger 30 in either the heating operation or the cooling operation, in which the liquid-gas heat exchanger 30 has a storage space 33 in which the circulating liquid refrigerant is stored. According to the above-described configuration, the storage space 33 capable of storing the liquid refrigerant is provided in the liquid-gas heat exchanger 30. Therefore, when the amount of refrigerant is excessive during the cooling operation or the heating operation, it is possible to store the excess refrigerant in the storage space 33. As a result, the total length of the refrigerant pipe is reduced as compared to a case where the receiver and the liquid-gas heat exchanger are separately provided, which makes it possible to reduce the total amount of refrigerant used. (2) According to a second aspect, in the air conditioner 1 according to (1), when the refrigerant is excessive during the heating operation, the switching portion 40 guides the liquid refrigerant to the liquid-gas heat exchanger 30 only during the heating operation of the heating operation and the cooling operation. Here, it is known that the amount of refrigerant during the heating operation is excessive when the internal volume of the pipe in the outdoor heat exchanger 15 is larger than the internal volume of the pipe in the indoor heat exchanger 12 or in the case of an operating condition in which the refrigerant pressure in the indoor heat exchanger 12 during the heating operation is relatively high. According to the above-described configuration, when the amount of refrigerant is excessive during the heating operation, it is possible to store the excess refrigerant in the storage space 33. On the other hand, the liquid refrigerant does not circulate through the liquid-gas heat exchanger 30 during the cooling operation. Therefore, it is possible to reduce the amount of refrigerant required during the cooling operation. This makes it possible to reduce the overall amount of refrigerant used. (3) According to a third aspect, in the air conditioner 1 according to (1), when the refrigerant is excessive during the cooling operation, the switching portion 40 guides the liquid refrigerant to the liquid-gas heat exchanger 30 only during the cooling operation of the heating operation and the cooling operation. Here, it is known that the amount of refrigerant during the cooling operation is excessive when the internal volume of the pipe in the indoor heat exchanger 12 is larger than the internal volume of the pipe in the outdoor heat exchanger 15 or in the case of an operating condition in which the refrigerant pressure in the outdoor heat exchanger 15 during the cooling operation is relatively high. According to the above-described configuration, when the amount of refrigerant is excessive during the cooling operation, it is possible to store the excess refrigerant in the storage space 33. On the other hand, the liquid refrigerant does not circulate through the liquid-gas heat exchanger 30 during the heating operation. Therefore, it is possible to reduce the amount of refrigerant required during the heating operation. This makes it possible to reduce the overall amount of refrigerant used. (4) An air conditioner 1 according to a fourth aspect includes: a refrigeration cycle 10 including an outdoor heat exchanger 15, an indoor heat exchanger 12, a compressor 11, and an expansion valve 14 through which a refrigerant circulates sequentially, a four-way valve 20 that switches a circulation direction of the refrigerant to enable a heating operation and a cooling operation, a liquid-gas heat exchanger 30 that is capable of exchanging heat between a low-pressure-side gas refrigerant and a high-pressure-side liquid refrigerant, a switching portion 40 that guides the 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 that is provided between the switching portion 40 and the indoor heat exchanger 12, in which the liquid-gas heat exchanger 30 has a storage space 33 in which the circulating liquid refrigerant is stored. According to the above-described configuration, since another expansion valve 14 is further provided between the switching portion 40 and the indoor heat exchanger 12, it is possible to cause the excess liquid refrigerant to circulate through the liquid-gas heat exchanger 30 regardless of whether the operation is the cooling operation or the heating operation. Therefore, it is possible to reduce the amount of excess refrigerant regardless of the operating state. (5) According to a fifth aspect, in the air conditioner 1 according to any one of (1) to (4), the liquid-gas heat exchanger 30 includes a gas pipe portion 31 through which the gas refrigerant circulates and a liquid pipe portion 32 that covers the gas pipe portion 31 from an outside to form the storage space 33 in which the liquid refrigerant is capable of circulating and being stored. According to the above-described configuration, it is possible to store the excess liquid refrigerant in the storage space 33, in addition to enabling heat exchange between the gas refrigerant flowing through the gas pipe portion 31 and the liquid refrigerant flowing through the liquid pipe portion 32. (6) According to a second aspect, in the air conditioner 1 according to any one of (1) to (4), the liquid-gas heat exchanger 30 includes a gas pipe portion 31 through which the gas refrigerant circulates and a liquid pipe portion 32 that covers the gas pipe portion 31 in a double-pipe shape from an outside to communicate with the storage space 33 in which the liquid refrigerant is capable of circulating and being stored.

[0045] According to the above-described configuration, it is possible to store the excess liquid refrigerant in the storage space 33, in addition to enabling heat exchange between the gas refrigerant flowing through the gas pipe portion 31 and the liquid refrigerant flowing through the liquid pipe portion 32. That is, it is possible to achieve both the functions of the receiver and the functions of the liquid-gas heat exchanger 30. In addition, since the liquid pipe portion 32 covers the gas pipe portion 31 in the double-pipe shape from the outside, the flow speed of the liquid refrigerant increases. Therefore, it is possible to further improve the efficiency of heat exchange between the liquid refrigerant and the gas refrigerant.Industrial Applicability

[0046] According to the present disclosure, it is possible to provide an air conditioner in which the amount of refrigerant is reduced while a liquid-gas heat exchanger is used.Reference Signs List

[0047] 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 pipe portion 32: Liquid pipe portion 33: Storage space 40: Switching portion 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 including 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 switches a circulation direction of the refrigerant to enable a heating operation and a cooling operation; a liquid-gas heat exchanger that is capable of exchanging heat between a low-pressure-side gas refrigerant and a high-pressure-side liquid refrigerant; and a switching portion that guides 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. The air conditioner according to Claim 1, wherein, when the refrigerant is excessive during the heating operation, the switching portion guides the liquid refrigerant to the liquid-gas heat exchanger only during the heating operation of the heating operation and the cooling operation.

3. The air conditioner according to Claim 1, wherein, when the refrigerant is excessive during the cooling operation, the switching portion guides the liquid refrigerant to the liquid-gas heat exchanger only during the cooling operation of the heating operation and the cooling operation.

4. An air conditioner comprising: a refrigeration cycle including 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 switches a circulation direction of the refrigerant to enable a heating operation and a cooling operation; a liquid-gas heat exchanger that is capable of exchanging heat between a low-pressure-side gas refrigerant and a high-pressure-side liquid refrigerant; a switching portion that guides 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 portion and the indoor heat exchanger, wherein the liquid-gas heat exchanger has a storage space in which the circulating liquid refrigerant is stored.

5. The air conditioner according to any one of Claims 1 to 4, wherein the liquid-gas heat exchanger includes a gas pipe portion through which the gas refrigerant circulates, and a liquid pipe portion that covers the gas pipe portion from an outside to form the storage space in which the liquid refrigerant is capable of circulating and being stored.

6. The air conditioner according to any one of Claims 1 to 4, wherein the liquid-gas heat exchanger includes a gas pipe portion through which the gas refrigerant circulates, and a liquid pipe portion that covers the gas pipe portion in a double-pipe shape from an outside to communicate with the storage space in which the liquid refrigerant is capable of circulating and being stored.

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