EP4589215A1

EP4589215A1 - Air conditioner

Info

Publication number: EP4589215A1
Application number: EP23872099.9A
Authority: EP
Inventors: Tomomitsu Yamaguchi; Keisuke Mitoma; Masamune OKINO; Yusuke Doi; Michiaki Nakanishi; Takaya KUSUMOTO; Masayoshi Hirasawa; Yasuaki Kaneko
Original assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Current assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Priority date: 2022-09-27
Filing date: 2023-09-21
Publication date: 2025-07-23
Also published as: WO2024070872A1; EP4589215A4; JP2024047891A; AU2023353614A1

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 sequentially circulates; a first four-way valve that makes it possible to switch between a heating operation and a cooling operation by switching the circulation direction of the refrigerant; a liquid gas heat exchanger that exchanges heat between the refrigerant in a gas state on the low-pressure side of the refrigeration cycle and the refrigerant in a liquid state on the high-pressure side; and a second four-way valve that switches the flow of the refrigerant such that the gas refrigerant and the liquid refrigerant have opposite flows in the liquid gas heat exchanger in both the heating operation and the cooling operation, wherein the second four-way valve is disposed in a region in the refrigeration cycle where the refrigerant in the gas state on the low-pressure side circulates.

Description

Technical Field

The present disclosure relates to an air conditioner.
Priority is claimed on Japanese Patent Application No. 2022-153649 filed on September 27, 2022 , the content of which is incorporated herein by reference.

Background Art

A refrigeration cycle includes an evaporator, a condenser, a compressor, and an expansion valve, and for example, during a cooling operation, a refrigerant sequentially circulates through the compressor, the condenser, the expansion valve, and the evaporator in this order. Here, it is desirable that the refrigerant returning from the evaporator to the compressor is in a gas phase at as low a temperature as possible in order to prevent liquid compression in the compressor. There is also a demand for suppressing generation of flash gas by supercooling the refrigerant in a refrigerant pipe.
Therefore, an air conditioner including a liquid-gas heat exchanger has been put into practical use. As a specific example of the air conditioner including the liquid-gas heat exchanger, a technique disclosed in PTL 1 is known. In the air conditioner according to PTL 1, for example, during a cooling operation, the liquid-gas heat exchanger performs heat exchange between a low-temperature gas-phase refrigerant that has passed through an evaporator and a high-temperature liquid-phase refrigerant that has passed through a condenser. As a result, it is said to be able to satisfy the two demands described above.
Incidentally, in the liquid-gas heat exchanger, it is desirable for the liquid-phase refrigerant and the gas-phase refrigerant to be in a counterflow state in which the liquid-phase refrigerant and the gas-phase refrigerant flow in opposite directions, from the viewpoint of ensuring thermal efficiency. Therefore, in a device according to PTL 1, a direction of the refrigerant flowing into the liquid-gas heat exchanger can be appropriately changed by a four-way valve between a cooling operation and a heating operation.

Citation List

Patent Literature

[PTL 1] Japanese Unexamined Patent Application Publication No. 2003-194432

Summary of Invention

Technical Problem

However, in the air conditioner according to PTL 1, both the low-temperature refrigerant and the high-temperature refrigerant flow inside the four-way valve. For this reason, inadvertent heat exchange may occur between the refrigerants inside the four-way valve, resulting in reduced operation efficiency.
The present disclosure has been made to solve the above-described problem, and an object of the present disclosure is to provide an air conditioner with further improved operation efficiency.

Solution to Problem

In order to solve the above problem, an air conditioner according to the present disclosure includes a refrigeration cycle including an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve through each of which a refrigerant sequentially circulates, a first four-way valve that enables a heating operation and a cooling operation by switching a circulation direction of the refrigerant, a liquid-gas heat exchanger that exchanges heat between a gas refrigerant on a low pressure side of the refrigeration cycle and a liquid refrigerant on a high pressure side of the refrigeration cycle, and a second four-way valve that switches a flow of the refrigerant such that the gas refrigerant and the liquid refrigerant are in a counterflow state in the liquid-gas heat exchanger, in both the heating operation and the cooling operation, in which the second four-way valve is disposed in a region in the refrigeration cycle where the refrigerant in a gas state on the low pressure side circulates.
An air conditioner according to the present disclosure includes a refrigeration cycle including an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve through each of which a refrigerant sequentially circulates, a first four-way valve that enables a heating operation and a cooling operation by switching a circulation direction of the refrigerant, a liquid-gas heat exchanger that exchanges heat between a gas refrigerant on a low pressure side of the refrigeration cycle and a liquid refrigerant on a high pressure side of the refrigeration cycle, a second four-way valve that switches a flow of the refrigerant such that the gas refrigerant and the liquid refrigerant are in a counterflow state in the liquid-gas heat exchanger, in both the heating operation and the cooling operation, and an accumulator that is provided upstream of the compressor and that separates the refrigerant into gas and liquid, in which the liquid-gas heat exchanger is disposed between the accumulator and the compressor.

Advantageous Effects of Invention

According to the present disclosure, it is possible to provide an air conditioner with further improved operation efficiency.

Brief Description of Drawings

Fig. 1 is a circuit diagram of an air conditioner according to a first embodiment of the present disclosure and is a diagram showing a flow of a refrigerant during a cooling operation.
Fig. 2 is a circuit diagram of the air conditioner according to the first embodiment of the present disclosure and is a diagram showing a flow of a refrigerant during a heating operation.
Fig. 3 is a circuit diagram of the air conditioner according to a second embodiment of the present disclosure and is a diagram showing a flow of a refrigerant during a cooling operation.
Fig. 4 is a circuit diagram of the air conditioner according to the second embodiment of the present disclosure and is a diagram showing a flow of a refrigerant during a heating operation.
Fig. 5 is a circuit diagram showing a modification example of the air conditioner according to the second embodiment of the present disclosure.

Description of Embodiments

(Configuration of Air Conditioner)

Hereinafter, an air conditioner 1 according to a first embodiment of the present disclosure will be described with reference to Figs. 1 and 2. The air conditioner 1 according to the present embodiment is, for example, a device that is installed in a building such as a house or a transport machine such as an automobile and that adjusts an indoor temperature to a designated value.
As shown in Fig. 1, the air conditioner 1 includes a refrigeration cycle 10, a first four-way valve 20, a liquid-gas heat exchanger 30, and a second four-way valve 40. The refrigeration cycle 10 is a circuit for exchanging heat between indoor air and a refrigerant and between outdoor air and a refrigerant by compressing or expanding a refrigerant that circulates sequentially through each device of the refrigeration cycle 10.

(Configuration of Refrigeration Cycle)

The refrigeration cycle 10 includes an indoor heat exchanger 11, an indoor fan 12, an outdoor heat exchanger 13, an outdoor fan 14, a compressor 15, an accumulator 16, a first expansion valve 17 (expansion valve), a second expansion valve 18 (expansion valve), a first flow channel 51, a second flow channel 52, a compressor flow channel 53, and a low-pressure gas flow channel 54.
The indoor heat exchanger 11 is disposed on the first flow channel 51. The first flow channel 51 is a flow channel that connects the first four-way valve 20 and the liquid-gas heat exchanger 30, which will be described below. An inside of the first flow channel 51 is filled with a refrigerant. The indoor heat exchanger 11 exchanges heat between the refrigerant circulating inside the first flow channel 51 and the indoor air. The indoor heat exchanger 11 is, for example, a fin-and-tube type heat exchanger. The indoor fan 12 is provided in the vicinity of the indoor heat exchanger 11. By operating the indoor fan 12, the indoor air is forcibly supplied to the indoor heat exchanger 11.
The first expansion valve 17 is disposed at a position on the liquid-gas heat exchanger 30 side of the indoor heat exchanger 11 on the first flow channel 51. The first expansion valve 17 is, for example, an electromagnetic expansion valve, and an opening degree thereof is adjusted by an electric signal transmitted from an outside. The first expansion valve 17 is used to expand the refrigerant flowing inside the first flow channel 51 to reduce a pressure of the refrigerant during a cooling operation.
The outdoor heat exchanger 13 is disposed on the second flow channel 52. The second flow channel 52 is a flow channel that connects the first four-way valve 20 and the liquid-gas heat exchanger 30, and is a flow channel provided separately from the first flow channel 51. An inside of the second flow channel 52 is filled with a refrigerant. The outdoor heat exchanger 13 exchanges heat between the refrigerant circulating inside the second flow channel 52 and the outdoor air. The outdoor heat exchanger 13 is, for example, a fin-and-tube type heat exchanger. The outdoor fan 14 is provided in the vicinity of the outdoor heat exchanger 13. By operating the outdoor fan 14, the outdoor air is forcibly supplied to the outdoor heat exchanger 13.
The second expansion valve 18 is disposed at a position on the liquid-gas heat exchanger 30 side of the outdoor heat exchanger 13 on the second flow channel 52. The second expansion valve 18 is, for example, an electromagnetic expansion valve, and an opening degree thereof is adjusted by an electric signal transmitted from an outside. The second expansion valve 18 is used to expand the refrigerant flowing inside the second flow channel 52 to reduce a pressure of the refrigerant during a heating operation.
The compressor 15 and the accumulator 16 are provided on the compressor flow channel 53. The compressor flow channel 53 is a flow channel that connects the liquid-gas heat exchanger 30 and the first four-way valve 20, and is another flow channel different from the first flow channel 51 and the second flow channel 52 described above. The compressor 15 compresses a gas refrigerant in the compressor flow channel 53 to generate a high-temperature and high-pressure gas refrigerant. Specifically, the compressor 15 is preferably a scroll compressor or a rotary compressor. The accumulator 16 is disposed adjacent to an upstream side of the compressor 15 on the compressor flow channel 53. The accumulator 16 separates the refrigerant into gas and liquid, sends only a gas phase component to the compressor 15, and stores a liquid phase component. The liquid phase component stored in the accumulator 16 also contains a lubricant mixed with the refrigerant.
The low-pressure gas flow channel 54 connects the first four-way valve 20 and the liquid-gas heat exchanger 30 in parallel with the compressor flow channel 53. The second four-way valve 40, which will be described below, is disposed on the low-pressure gas flow channel 54.

(Configuration of First Four-Way Valve)

The first four-way valve 20 switches a circulation direction of the refrigerant by switching a connection state of the first flow channel 51, the second flow channel 52, the compressor flow channel 53, and the low-pressure gas flow channel 54. The heating operation and the cooling operation can be switched by switching an open state of the first four-way valve 20. Fig. 1 shows the open state of the first four-way valve 20 during the cooling operation. Specifically, the compressor flow channel 53 and the second flow channel 52 are connected, and the first flow channel 51 and the low-pressure gas flow channel 54 are connected. A state during the heating operation will be described below with reference to Fig. 2.

(Configuration of Liquid-Gas Heat Exchanger)

The liquid-gas heat exchanger 30 is provided at a position where an end portion of the first flow channel 51 on the first expansion valve 17 side and an end portion of the second flow channel 52 on the second expansion valve 18 side are connected. In addition, the liquid-gas heat exchanger 30 connects the low-pressure gas flow channel 54 and the compressor flow channel 53. As a result, during the cooling operation shown in Fig. 1, heat is exchanged between a high-temperature and high-pressure liquid refrigerant flowing from the second flow channel 52 toward the first flow channel 51 and a low-temperature and low-pressure gas refrigerant flowing from the low-pressure gas flow channel 54 toward the compressor flow channel 53. In the liquid-gas heat exchanger 30, flow directions of the two refrigerants are determined such that the two refrigerants flow in opposite directions, that is, in a counterflow state.

(Configuration of Second Four-Way Valve)

The second four-way valve 40 switches the flow of the refrigerant such that the two refrigerants in the liquid-gas heat exchanger 30 are in the counterflow state in both the heating operation and the cooling operation. Specifically, the second four-way valve 40 switches an open state between the low-pressure gas flow channel 54 and the compressor flow channel 53 and the liquid-gas heat exchanger 30. During the cooling operation shown in Fig. 1, the refrigerant that has passed through the low-pressure gas flow channel 54 heads toward the compressor flow channel 53 via the liquid-gas heat exchanger 30. At this time, an open state of the second four-way valve 40 is switched such that a flow direction of the refrigerant is opposite to a flow direction of the refrigerant from the second flow channel 52 toward the first flow channel 51.
The second four-way valve 40 is provided in a region (that is, on the low-pressure gas flow channel 54) where the low-pressure gas refrigerant normally circulates. In other words, it is desirable that the second four-way valve 40 is provided between the indoor heat exchanger 11 and the compressor 15. More desirably, the second four-way valve 40 is provided between the first four-way valve 20 and the liquid-gas heat exchanger 30.

(Effects)

Subsequently, an example of an operation of the air conditioner 1 will be described with reference to Figs. 1 and 2. Fig. 1 shows a circuit state of the air conditioner 1 during the cooling operation. As shown in Fig. 1, first, the gas refrigerant compressed by the compressor 15 and thus attaining a high temperature and a high pressure flows to the outdoor heat exchanger 13 on the second flow channel 52 via the first four-way valve 20. The gas refrigerant that has exchanged heat with the outdoor air in the outdoor heat exchanger 13 becomes a high-pressure liquid refrigerant. Thereafter, the refrigerant passes through the second expansion valve 18 on the second flow channel 52. During the cooling operation, the second expansion valve 18 is in a fully open state, and a pressure of the refrigerant does not change even when the refrigerant passes through the second expansion valve 18.
Next, the refrigerant that has passed through the second flow channel 52 flows into the liquid-gas heat exchanger 30. In the liquid-gas heat exchanger 30, the high-temperature and high-pressure liquid refrigerant that has passed through the second flow channel 52 exchanges heat with a low-temperature and low-pressure gas refrigerant, which will be described below. As a result, the refrigerant that passes through the liquid-gas heat exchanger 30 and flows into the first flow channel 51 has a lowered temperature and an increased degree of supercooling. The supercooled refrigerant then passes through the first expansion valve 17. As a result, the refrigerant expands to become a low-temperature and low-pressure liquid refrigerant. Thereafter, the refrigerant that flowed into the indoor heat exchanger 11 exchanges with the indoor air, and vaporizes as a temperature of the refrigerant rises to become a low-pressure gas refrigerant.
The low-pressure gas refrigerant passes through the first four-way valve 20 and flows into the low-pressure gas flow channel 54. Thereafter, the low-pressure gas refrigerant passes through the second four-way valve 40 and exchanges heat with the above-described high-temperature and high-pressure liquid refrigerant in the liquid-gas heat exchanger 30. As a result, the low-pressure gas refrigerant is superheated. The superheated low-pressure gas refrigerant passes through the second four-way valve 40 again, and then flows to the accumulator 16 and the compressor 15. The air conditioner 1 is operated for cooling by the above cycle occurring continuously.
Next, an operation of the air conditioner 1 during the heating operation will be described with reference to Fig. 2. As shown in Fig. 2, first, the gas refrigerant compressed by the compressor 15 and thus attaining a high temperature and a high pressure flows to the indoor heat exchanger 11 on the first flow channel 51 via the first four-way valve 20. The gas refrigerant that has exchanged heat with the indoor air in the indoor heat exchanger 11 becomes a high-pressure liquid refrigerant. Thereafter, the refrigerant passes through the first expansion valve 17 on the first flow channel 51. During the heating operation, the first expansion valve 17 is in a fully open state, and a pressure of the refrigerant does not change even when the refrigerant passes through the first expansion valve 17.
Next, the refrigerant that has passed through the first flow channel 51 flows into the liquid-gas heat exchanger 30. In the liquid-gas heat exchanger 30, the high-temperature and high-pressure liquid refrigerant that has passed through the first flow channel 51 exchanges heat with a low-temperature and low-pressure gas refrigerant, which will be described below. As a result, the refrigerant that passes through the liquid-gas heat exchanger 30 and flows into the second flow channel 52 has a lowered temperature and an increased degree of supercooling. The supercooled refrigerant then passes through the second expansion valve 18. As a result, the refrigerant expands to become a low-temperature and low-pressure liquid refrigerant. Thereafter, the refrigerant that flowed into the outdoor heat exchanger 13 exchanges with the outdoor air, and vaporizes as a temperature of the refrigerant rises to become a low-pressure gas refrigerant.
The low-pressure gas refrigerant passes through the first four-way valve 20 and flows into the low-pressure gas flow channel 54. Thereafter, the low-pressure gas refrigerant passes through the second four-way valve 40 and exchanges heat with the above-described high-temperature and high-pressure liquid refrigerant in the liquid-gas heat exchanger 30. As a result, the low-pressure gas refrigerant is superheated. The superheated low-pressure gas refrigerant passes through the second four-way valve 40 again, and then flows to the accumulator 16 and the compressor 15. The air conditioner 1 is operated for heating by the above cycle occurring continuously.
Here, it is desirable that the refrigerant returning from the indoor heat exchanger 11 or the outdoor heat exchanger 13 serving as the evaporator to the compressor 15 is a gas refrigerant with as low a temperature as possible in order to prevent liquid compression in the compressor 15. There is also a demand for suppressing generation of flash gas by supercooling the refrigerant in a refrigerant pipe. Therefore, in the air conditioner 1 according to the present embodiment, the liquid-gas heat exchanger 30 meets these two demands. Specifically, by using the liquid-gas heat exchanger 30, heat can be exchanged between the high-temperature and high-pressure liquid refrigerant and the low-temperature and low-pressure gas refrigerant. As a result, the refrigerant returning from the evaporator to the compressor 15 is further vaporized and becomes a gas refrigerant that does not contain a liquid phase component. Therefore, the probability of liquid compression occurring in the compressor 15 is reduced, and the compressor 15 can be operated more stably. On the other hand, the refrigerant flowing through the first flow channel 51 or the second flow channel 52 is supercooled and reaches a lower temperature. As a result, the generation of flash gas can be suppressed.
Here, in the liquid-gas heat exchanger 30, it is desirable for the liquid refrigerant and the gas refrigerant to be in a counterflow state in which the liquid refrigerant and the gas refrigerant flow in opposite directions, from the viewpoint of ensuring thermal efficiency. In order to realize such a state during both the cooling operation and the heating operation, the above-described configurations are adopted.
With the above-described configuration, the second four-way valve 40 is disposed in a region (on the low-pressure gas flow channel 54) where only a refrigerant in a gas state on a low-pressure side flows. That is, a refrigerant on a high-pressure side having a different temperature does not flow into the second four-way valve 40. Therefore, the probability that inadvertent heat exchange occurs between a low-temperature refrigerant and a high-temperature refrigerant inside the second four-way valve 40 can be reduced. As a result, the amount of heat of the refrigerant is stably maintained across the second four-way valve 40, so that the operation efficiency of the air conditioner 1 can be further improved.
In addition, with the above-described configuration, the second four-way valve 40 is disposed between the indoor heat exchanger 11 and the compressor 15. Therefore, for example, during the cooling operation, only the low-pressure refrigerant that has passed through the indoor heat exchanger 11 flows into the second four-way valve 40. As a result, the probability that inadvertent heat exchange occurs between the low-temperature refrigerant and the high-temperature refrigerant inside the second four-way valve 40 can be reduced. Therefore, the amount of heat of the refrigerant is stably maintained across the second four-way valve 40, so that the operation efficiency of the air conditioner 1 can be further improved.
In addition, with the above-described configuration, the second four-way valve 40 is disposed between the first four-way valve 20 and the liquid-gas heat exchanger 30. Therefore, regardless of whether the air conditioner 1 is in the cooling operation or the heating operation, only the low-pressure refrigerant that has passed through the first four-way valve 20 flows into the second four-way valve 40. As a result, the probability that inadvertent heat exchange occurs between the low-temperature refrigerant and the high-temperature refrigerant inside the second four-way valve 40 can be reduced. As a result, the operation efficiency of the air conditioner 1 can be further improved.
The first embodiment of the present disclosure has been described above. Various changes or improvements can be made to the above configuration without departing from the concept of the present disclosure.

Next, a second embodiment of the present disclosure will be described with reference to Figs. 3 and 4. The same configurations as in the first embodiment are denoted by the same reference signs, and detailed descriptions thereof will be omitted. As shown in Fig. 3, in the present embodiment, a position where the accumulator 16 is provided is different from that in the first embodiment. Specifically, the accumulator 16 is provided between the first four-way valve 20 and the liquid-gas heat exchanger 30 on the low-pressure gas flow channel 54. In other words, the second four-way valve 40 and the liquid-gas heat exchanger 30 are disposed between the accumulator 16 and the compressor 15. In other words, the liquid-gas heat exchanger 30 is provided downstream of the accumulator 16. In addition, the compressor 15 is provided downstream of the liquid-gas heat exchanger 30.

(Effects)

With the above-described configuration, since the liquid-gas heat exchanger 30 is disposed downstream of the accumulator 16, a refrigerant flowing into the accumulator 16 is not subjected to heat exchange in the liquid-gas heat exchanger 30 and is not superheated. As a result, fluidity of a lubricant mixed with the refrigerant in the accumulator 16 can be kept low. Therefore, the lubricant can be smoothly guided to each part of the compressor 15.
In particular, it is known that in a refrigerant such as R290, which is mainly composed of propane and which has been increasingly introduced in recent years, fluidity of a lubricant tends to decrease as a temperature rises. Therefore, when the refrigerant is superheated, there is a probability that the lubricant having low fluidity accumulates in the accumulator 16. However, with the above-described configuration, the refrigerant flowing into the accumulator 16 is not superheated, so that it is possible to significantly reduce such a probability. As a result, the air conditioner 1 can be operated more stably.
In addition, with the above-described configuration, the compressor 15 is disposed downstream of the liquid-gas heat exchanger 30, so that the superheated refrigerant flows into the compressor 15. As a result, a liquid phase component of the refrigerant is further vaporized, so that the probability of liquid compression occurring in the compressor 15 can be further reduced.
In addition, with the above-described configuration, the second four-way valve 40 is provided between the accumulator 16 and the liquid-gas compressor 15. As a result, as described in the first embodiment, the low-pressure side refrigerant and the high-pressure side refrigerant in the liquid-gas heat exchanger 30 can flow in such a manner that the refrigerants are in the counterflow state. As a result, the heat exchange efficiency in the liquid-gas heat exchanger 30 can be further improved.
Fig. 3 shows a flow of the refrigerant and an open state of each valve during the cooling operation, and Fig. 4 shows a flow of the refrigerant and an open state of each valve during the heating operation. As shown in Figs. 3 and 4, during any operation, the flow of the refrigerant and the open state of the valve are the same as those in the first embodiment. In addition, the above-described effects can be obtained in either operation.
The second embodiment of the present disclosure has been described above. Various changes or improvements can be made to the above configuration without departing from the concept of the present disclosure. For example, in the second embodiment, an example in which the second four-way valve 40 and the liquid-gas heat exchanger 30 are disposed between the accumulator 16 and the compressor 15 has been described. However, as shown in Fig. 5 as a modification example, only the liquid-gas heat exchanger 30 may be disposed between the accumulator 16 and the compressor 15, and the second four-way valve 40 may be disposed upstream of the accumulator 16.

The air conditioner 1 according to each embodiment is understood, for example, as follows.

(1) A first aspect provides an air conditioner 1 including a refrigeration cycle 10 including an outdoor heat exchanger 13, an indoor heat exchanger 11, a compressor 15, and an expansion valve through each of which a refrigerant sequentially circulates, a first four-way valve 20 that enables a heating operation and a cooling operation by switching a circulation direction of the refrigerant, a liquid-gas heat exchanger 30 that exchanges heat between a gas refrigerant on a low pressure side of the refrigeration cycle 10 and a liquid refrigerant on a high pressure side of the refrigeration cycle 10, and a second four-way valve 40 that switches a flow of the refrigerant such that the gas refrigerant and the liquid refrigerant are in a counterflow state in the liquid-gas heat exchanger 30, in both the heating operation and the cooling operation, in which the second four-way valve 40 is disposed in a region in the refrigeration cycle 10 where the refrigerant in a gas state on the low pressure side circulates.
With the above-described configuration, the second four-way valve 40 is disposed in a region where only the refrigerant in the gas state on the low-pressure side flows. That is, the refrigerant on the high pressure side does not flow into the second four-way valve 40. Therefore, the probability that inadvertent heat exchange occurs between a low-temperature refrigerant and a high-temperature refrigerant inside the second four-way valve 40 can be reduced. As a result, the operation efficiency of the air conditioner 1 can be further improved.
(2) A second aspect provides the air conditioner 1 according to (1), in which the second four-way valve 40 is disposed between the indoor heat exchanger 11, which functions as an evaporator during the cooling operation, and the compressor 15.
With the above-described configuration, the second four-way valve 40 is disposed between the indoor heat exchanger 11 and the compressor 15. Therefore, for example, during the cooling operation, only the low-pressure refrigerant that has passed through the indoor heat exchanger 11 flows into the second four-way valve 40. As a result, the probability that inadvertent heat exchange occurs between the low-temperature refrigerant and the high-temperature refrigerant inside the second four-way valve 40 can be reduced. As a result, the operation efficiency of the air conditioner 1 can be further improved.
(3) A third aspect provides the air conditioner 1 according to (1) or (2), in which the second four-way valve 40 is disposed between the first four-way valve 20 and the liquid-gas heat exchanger 30.
With the above-described configuration, the second four-way valve 40 is disposed between the first four-way valve 20 and the liquid-gas heat exchanger 30. Therefore, regardless of whether the air conditioner 1 is in the cooling operation or the heating operation, only the low-pressure refrigerant that has passed through the first four-way valve 20 flows into the second four-way valve 40. As a result, the probability that inadvertent heat exchange occurs between the low-temperature refrigerant and the high-temperature refrigerant inside the second four-way valve 40 can be reduced. As a result, the operation efficiency of the air conditioner 1 can be further improved.
(4) A fourth aspect provides the air conditioner 1 according to any one of (1) to (3), in which the refrigeration cycle 10 further includes an accumulator 16 that is provided upstream of the compressor 15 and that separates the refrigerant into gas and liquid, and the liquid-gas heat exchanger 30 and the second four-way valve 40 are disposed between the accumulator 16 and the compressor 15.
With the above-described configuration, since the liquid-gas heat exchanger 30 is disposed downstream of the accumulator 16, a refrigerant flowing into the accumulator 16 is not superheated. As a result, fluidity of a lubricant mixed with the refrigerant in the accumulator 16 can be kept low. Therefore, the lubricant can be smoothly guided to each part of the compressor 15. In addition, the compressor 15 is disposed downstream of the liquid-gas heat exchanger 30, so that the superheated refrigerant flows into the compressor 15. As a result, a liquid phase component of the refrigerant is vaporized, so that the probability of liquid compression occurring in the compressor 15 can be reduced.
(5) A fifth aspect provides an air conditioner 1 including a refrigeration cycle 10 including an outdoor heat exchanger 13, an indoor heat exchanger 11, a compressor 15, and an expansion valve through each of which a refrigerant sequentially circulates, a first four-way valve 20 that enables a heating operation and a cooling operation by switching a circulation direction of the refrigerant, a liquid-gas heat exchanger 30 that exchanges heat between a gas refrigerant on a low pressure side of the refrigeration cycle 10 and a liquid refrigerant on a high pressure side of the refrigeration cycle, a second four-way valve 40 that switches a flow of the refrigerant such that the gas refrigerant and the liquid refrigerant are in a counterflow state in the liquid-gas heat exchanger 30, in both the heating operation and the cooling operation, and an accumulator 16 that is provided upstream of the compressor 15 and that separates the refrigerant into gas and liquid, in which the liquid-gas heat exchanger 30 is disposed between the accumulator 16 and the compressor 15.
With the above-described configuration, since the liquid-gas heat exchanger 30 is disposed downstream of the accumulator 16, a refrigerant flowing into the accumulator 16 is not superheated. As a result, fluidity of a lubricant mixed with the refrigerant in the accumulator 16 can be kept low. Therefore, the lubricant can be smoothly guided to each part of the compressor 15. In addition, the compressor 15 is disposed downstream of the liquid-gas heat exchanger 30, so that the superheated refrigerant flows into the compressor 15. As a result, a liquid phase component of the refrigerant is vaporized, so that the probability of liquid compression occurring in the compressor 15 can be reduced.
(6) An air conditioner 1 according to a sixth aspect is the air conditioner 1 according to (5), in which the second four-way valve 40 is provided between the accumulator 16 and the liquid-gas heat exchanger 30.

With the above-described configuration, since the second four-way valve 40 is provided between the accumulator 16 and the liquid-gas compressor 15, the low-pressure side refrigerant and the high-pressure side refrigerant in the liquid-gas heat exchanger 30 can flow in such a manner that the refrigerants are in the counterflow state. As a result, the heat exchange efficiency in the liquid-gas heat exchanger 30 can be further improved.

Industrial Applicability

Reference Signs List

1: air conditioner
10: refrigeration cycle
11: indoor heat exchanger
12: indoor fan
13: outdoor heat exchanger
14: outdoor fan
15: compressor
16: accumulator
17: first expansion valve
18: second expansion valve
20: first four-way valve
30: liquid-gas heat exchanger
40: second four-way valve
51: first flow channel
52: second flow channel
53: compressor flow channel
54: low-pressure gas flow channel

Claims

An air conditioner comprising:
a refrigeration cycle including an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve through each of which a refrigerant sequentially circulates;

a first four-way valve that enables a heating operation and a cooling operation by switching a circulation direction of the refrigerant;

a liquid-gas heat exchanger that exchanges heat between a gas refrigerant on a low pressure side of the refrigeration cycle and a liquid refrigerant on a high pressure side of the refrigeration cycle; and

a second four-way valve that switches a flow of the refrigerant such that the gas refrigerant and the liquid refrigerant are in a counterflow state in the liquid-gas heat exchanger, in both the heating operation and the cooling operation,

wherein the second four-way valve is disposed in a region in the refrigeration cycle where the refrigerant in a gas state on the low pressure side circulates.
The air conditioner according to Claim 1,
wherein the second four-way valve is disposed between the indoor heat exchanger, which functions as an evaporator during the cooling operation, and the compressor.
The air conditioner according to Claim 1 or 2,
wherein the second four-way valve is disposed between the first four-way valve and the liquid-gas heat exchanger.
The air conditioner according to Claim 1,
wherein the refrigeration cycle further includes an accumulator that is provided upstream of the compressor and that separates the refrigerant into gas and liquid, and

the liquid-gas heat exchanger and the second four-way valve are disposed between the accumulator and the compressor.
An air conditioner comprising:
a refrigeration cycle including an outdoor heat exchanger, an indoor heat exchanger, a compressor, and an expansion valve through each of which a refrigerant sequentially circulates;

a first four-way valve that enables a heating operation and a cooling operation by switching a circulation direction of the refrigerant;

a liquid-gas heat exchanger that exchanges heat between a gas refrigerant on a low pressure side of the refrigeration cycle and a liquid refrigerant on a high pressure side of the refrigeration cycle;

a second four-way valve that switches a flow of the refrigerant such that the gas refrigerant and the liquid refrigerant are in a counterflow state in the liquid-gas heat exchanger, in both the heating operation and the cooling operation; and

an accumulator that is provided upstream of the compressor and that separates the refrigerant into gas and liquid,

wherein the liquid-gas heat exchanger is disposed between the accumulator and the compressor.
The air conditioner according to Claim 5,
wherein the second four-way valve is provided between the accumulator and the liquid-gas heat exchanger.