JP2024047894A - Air conditioner - Google Patents

Abstract

To provide an air conditioner which can be operated more stably with high refrigeration efficiency.SOLUTION: An air conditioner comprises: a compressor that compresses a refrigerant containing a refrigerator oil; an outdoor heat exchanger that exchanges heat between the refrigerant discharged from the compressor and outside air; a first expansion valve and a second expansion valve that sequentially depressurize the refrigerant which has passed through the outdoor heat exchanger; and an indoor heat exchanger that exchanges heat between the refrigerant which has passed through the expansion valves, and outside air, and that supplies the refrigerant to the compressor. The air conditioner further comprises a gas-liquid separation mechanism provided between the first expansion valve and the second expansion valve. The gas-liquid separation mechanism includes: a storage unit into which the refrigerant which has passed through the first expansion valve is introduced; and a first recirculation unit that is capable of recovering a liquid phase from a bottom part of the storage unit and introducing the liquid phase into the compressor.SELECTED DRAWING: Figure 1

Description

This disclosure relates to an air conditioner.

Various types of air conditioners that use gas injection have been put into practical use. Gas injection air conditioners are configured so that a portion of the gas refrigerant that has evaporated through the evaporator is extracted from the middle of the refrigerant circuit and returned to the compressor. The following Patent Document 1 discloses a configuration in which, of the liquid refrigerant and gas refrigerant generated in the gas-liquid separation mechanism, the gas refrigerant is returned to the compressor.

Here, the refrigeration oil that lubricates each part of the compressor is dissolved in the refrigerant and circulates through the refrigerant circuit. In the configuration using the gas-liquid separation mechanism described above, most of the refrigeration oil is separated together with the liquid refrigerant and remains stored in the gas-liquid separator.

In addition to the above, a configuration is also possible in which the refrigeration oil is separated from the refrigerant by an oil separator installed downstream of the compressor and returned to the compressor.

JP 2002-81779 A

However, when most of the refrigeration oil is dissolved in the liquid refrigerant and stored in the gas-liquid separation mechanism, as in the device of Patent Document 1, there is a possibility that the refrigeration oil will not reach the compressor that actually requires it. In addition, when an oil separator is used, some of the refrigerant will also be refluxed along with the refrigeration oil that returns to the compressor, which may reduce the refrigeration efficiency of the air conditioner. For this reason, there has been a growing demand for air conditioners that can be operated more stably with high refrigeration efficiency.

The present disclosure has been made to solve the above problems, and aims to provide an air conditioner that can be operated more stably with high refrigeration efficiency.

In order to solve the above problems, the air conditioner according to the present disclosure includes a compressor that compresses a refrigerant containing refrigeration oil, an outdoor heat exchanger that exchanges heat between the refrigerant discharged from the compressor and outside air, a first expansion valve and a second expansion valve that sequentially reduce the pressure of the refrigerant that has passed through the outdoor heat exchanger, and an indoor heat exchanger that exchanges heat between the refrigerant that has passed through either the first expansion valve or the second expansion valve and outside air and supplies the refrigerant to the compressor, and further includes a gas-liquid separation mechanism provided between the first expansion valve and the second expansion valve, and the gas-liquid separation mechanism has a storage section into which the refrigerant that has passed through the first expansion valve is introduced, and a first reflux section that can recover a liquid phase portion from the bottom of the storage section and introduce it to the compressor.

This disclosure makes it possible to provide an air conditioner that can be operated more stably with high refrigeration efficiency.

1 is a schematic diagram showing a refrigerant circuit of an air conditioner according to a first embodiment of the present disclosure. FIG. 4 is a schematic diagram showing a refrigerant circuit of an air conditioner according to a second embodiment of the present disclosure.

First Embodiment
(Configuration of the air conditioner)
An air conditioner 1 according to a first embodiment of the present disclosure will be described below with reference to Fig. 1. The air conditioner 1 according to this embodiment is a device that is installed in a building such as a house or in transportation machinery such as an automobile, for adjusting the indoor temperature to a specified value.

As shown in FIG. 1, the air conditioner 1 includes a refrigeration cycle 10, a four-way valve 20, and a gas-liquid separation mechanism 30. The refrigeration cycle 10 is a circuit for performing heat exchange between the indoor air and the refrigerant, and between the outdoor air and the refrigerant, by compressing and expanding the refrigerant that flows sequentially through each device (described below) of the refrigeration cycle 10.

(Configuration of refrigeration cycle)
The refrigeration cycle 10 has an indoor heat exchanger 11, an indoor fan 12, an outdoor heat exchanger 13, an outdoor fan 14, a compressor 15, a first expansion valve 17, a second expansion valve 18, a first flow path 41, a second flow path 42, and a compressor flow path 43.

The indoor heat exchanger 11 is disposed on the first flow path 41. The first flow path 41 is a flow path that connects between the four-way valve 20 and the gas-liquid separation mechanism 30, which will be described later. The inside of the first flow path 41 is filled with a refrigerant. The indoor heat exchanger 11 exchanges heat between the refrigerant flowing through the first flow path 41 and the indoor air. The indoor heat exchanger 11 is, for example, a fin-and-tube type heat exchanger. An indoor fan 12 is provided near the indoor heat exchanger 11. By operating the indoor fan 12, the indoor air is forcibly supplied to the indoor heat exchanger 11.

A second expansion valve 18 is disposed on the first flow path 41 at a position closer to the gas-liquid separation mechanism 30 than the indoor heat exchanger 11. The second expansion valve 18 is, for example, an electromagnetic expansion valve, and its opening is adjusted by an electrical signal sent from the outside. The second expansion valve 18 is used to expand the refrigerant flowing in the first flow path 41 during cooling operation, thereby reducing its pressure.

The outdoor heat exchanger 13 is disposed on the second flow path 42. The second flow path 42 is a flow path that connects the four-way valve 20 and the gas-liquid separation mechanism 30, and is a flow path provided separately from the first flow path 41. The second flow path 42 is filled with a refrigerant. The outdoor heat exchanger 13 exchanges heat between the refrigerant flowing through the second flow path 42 and the outdoor air. The outdoor heat exchanger 13 is, for example, a fin-and-tube type heat exchanger. An outdoor fan 14 is provided near the outdoor heat exchanger 13. By operating the outdoor fan 14, outdoor air is forcibly supplied to the outdoor heat exchanger 13.

A first expansion valve 17 is disposed on the second flow path 42 at a position closer to the gas-liquid separation mechanism 30 than the outdoor heat exchanger 13. The first expansion valve 17 is, for example, an electromagnetic expansion valve, and its opening is adjusted by an electrical signal sent from the outside. The first expansion valve 17 is used to expand the refrigerant flowing in the second flow path 42 during heating operation, thereby reducing its pressure.

The compressor 15 is provided on the compressor flow path 43. The compressor flow path 43 is a flow path that connects one opening of the four-way valve 20 to another opening, and is a flow path different from the first flow path 41 and the second flow path 42 described above. The compressor 15 compresses the gas refrigerant in the compressor flow path 43 to generate high-temperature, high-pressure gas refrigerant. Specifically, a scroll compressor or a rotary compressor is preferably used as the compressor 15.

(Configuration of four-way valve)
The four-way valve 20 switches the flow direction of the refrigerant by switching the connection state of the first flow path 41, the second flow path 42, and the compressor flow path 43. By switching the open state of the four-way valve 20, it is possible to switch between heating operation and cooling operation. Fig. 1 shows the open state of the four-way valve 20 during cooling operation. Specifically, the open state of the four-way valve 20 is set so that the high-pressure refrigerant discharged from the compressor 15 flows directly to the outdoor heat exchanger 13 via the second flow path 42.

(Configuration of gas-liquid separation mechanism)
Between the first expansion valve 17 and the second expansion valve 18 (i.e., between the first flow path 41 and the second flow path 42), a gas-liquid separation mechanism 30 is provided. The gas-liquid separation mechanism 30 has a storage section 31, a first reflux section 32, a first adjustment valve 33, and a second reflux section 34.

The storage section 31 is a sealed container in which the refrigerant is stored, and the refrigerant that has passed through the first expansion valve 17 is introduced into the storage section 31. Inside the storage section 31, the liquid phase of the refrigerant is stored at the bottom, and the gas phase is retained at the top. In other words, gas-liquid separation of the refrigerant is performed inside the storage section 31. The refrigerant contains refrigeration oil used to lubricate each part of the compressor 15. In the gas-liquid separation mechanism 30, most of this refrigeration oil is stored as a liquid phase at the bottom of the storage section 31.

The first reflux section 32 connects the bottom of the storage section 31 and the inlet side of the compressor 15. The first reflux section 32 recovers the liquid phase of the refrigerant, including the refrigeration oil, from the bottom of the storage section 31 and introduces it into the compressor 15. A first adjustment valve 33 is provided at a midpoint of the first reflux section 32. The first adjustment valve 33 is, for example, a flow rate adjustment valve. By adjusting the opening degree of the first adjustment valve 33, the flow rate of the liquid phase of the refrigerant flowing through the first reflux section 32 changes.

The second reflux section 34 connects the bottom of the storage section 31 and the second expansion valve 18, and forms part of the first passage described above. The second reflux section 34 recovers the liquid phase of the refrigerant from the bottom of the storage section 31 and introduces it into the first flow path 41. The liquid phase of the refrigerant introduced into the first flow path 41 is supplied to the indoor heat exchanger 11 via the second expansion valve 18.

(Action and Effect)
Next, the operation of the air conditioner 1 will be described. Note that here, the operation during cooling operation will be described as a representative example. During cooling operation of the air conditioner 1, the refrigerant flows through each part in accordance with the arrows in FIG. 1. First, the refrigerant (gas phase) compressed by the compressor 15 becomes a high-temperature, high-pressure gas phase refrigerant. The refrigerant then passes through the four-way valve 20 and is introduced into the outdoor heat exchanger 13. In the outdoor heat exchanger 13, heat exchange occurs between the outdoor air and the refrigerant. As a result, the refrigerant becomes a high-pressure gas-liquid mixed phase state. Then, the refrigerant passes through the first expansion valve 17 on the second flow path 42. Note that during cooling operation, the first expansion valve 17 is fully open, and the pressure of the refrigerant does not change even when it passes through the first expansion valve 17.

The refrigerant that has passed through the first expansion valve 17 is separated into a gas phase and a liquid phase by the gas-liquid separation mechanism 30. The liquid phase is stored at the bottom of the storage section 31, and the gas phase is stored at the top of the storage section 31. Refrigeration oil, which is a part of the liquid phase, is introduced into the compressor 15 through the first reflux section 32 described above. The refrigeration oil is used to lubricate each part of the compressor 15. The other part of the liquid phase stored in the storage section 31 is introduced into the first flow path 41 through the second reflux section 34. By passing through the second expansion valve 18 on the first flow path 41, the pressure of the refrigerant decreases and it becomes a low-temperature, low-pressure liquid refrigerant. Then, heat exchange between the indoor air and the refrigerant is performed in the indoor heat exchanger 11. As a result, the temperature of the refrigerant increases and the temperature of the indoor air decreases. The refrigerant also becomes a low-pressure gas phase state. Then, the refrigerant that flows into the compressor flow path 43 through the four-way valve 20 is compressed again by the compressor 15. The above cycle occurs continuously, causing the air conditioner 1 to perform cooling operation.

By the way, various types of air conditioners 1 that use gas injection have been put into practical use. In gas injection air conditioners 1, a configuration is adopted in which a portion of the gas refrigerant that has vaporized through the evaporator is taken from the middle of the refrigerant circuit and returned to the compressor 15. Specifically, of the liquid refrigerant and gas refrigerant generated in the gas-liquid separation mechanism 30, only the gas refrigerant is returned to the compressor 15. Here, the refrigeration oil that lubricates each part of the compressor 15 is dissolved in the refrigerant and circulates through the refrigerant circuit. In the configuration using the gas-liquid separation mechanism 30, most of the refrigeration oil is separated together with the liquid refrigerant and remains stored in the gas-liquid separator.

However, if most of the refrigeration oil is dissolved in the liquid refrigerant and stored in the gas-liquid separation mechanism 30 as described above, there is a possibility that the refrigeration oil will not reach the compressor 15 that actually requires it. Therefore, in this embodiment, the above-mentioned configurations are adopted.

According to the above configuration, the liquid phase component separated by the gas-liquid separation mechanism 30 is introduced into the compressor 15 through the first reflux section 32. This allows the refrigeration oil contained in the liquid phase component to be used as a lubricant in each part of the compressor 15 without waste. As a result, the smooth operation of the compressor 15 is maintained for a long period of time, allowing the compressor 15 to be operated more stably. By improving the operability of the compressor 15, the performance of the air conditioner 1 can also be improved.

Furthermore, according to the above configuration, a first adjustment valve 33 is provided on the first reflux section 32. By adjusting the opening degree of this first adjustment valve 33, the flow rate of the liquid phase component flowing through the first reflux section 32 can be maintained constant at a predetermined value. In addition, the supply of the liquid phase component can be reduced to zero as necessary. This makes it possible to optimize the supply amount of refrigeration oil contained in the liquid phase component according to the usage status of the compressor 15. Therefore, it becomes possible to operate the air conditioner 1 under a wide range of operating conditions according to the environment and specifications.

In addition, in the above configuration, the liquid phase of the refrigerant is introduced into the indoor heat exchanger 11 by the second reflux section 34. Here, it is known that when the gas phase of the refrigerant flows through the indoor heat exchanger 11 instead of the liquid phase, the pressure loss becomes larger than that of the liquid phase. This tendency is particularly noticeable in fin-and-tube type heat exchangers. According to the above configuration, the liquid phase of the refrigerant that has been separated into gas and liquid is introduced into the indoor heat exchanger 11 by the second reflux section 34. This suppresses the pressure loss in the indoor heat exchanger 11. As a result, the refrigerant continues to pass smoothly through the indoor heat exchanger 11, making it possible to operate the entire air conditioner 1 more efficiently.

The above describes the first embodiment of the present disclosure. Various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure. In the above first embodiment, only the cooling operation of the air conditioner 1 has been described. However, during heating operation, the flow direction of the refrigerant in the first flow path 41 and the second flow path 42, excluding the compressor flow path 43, is reversed. During heating operation, in the gas-liquid separation mechanism 30, the refrigerant flows from the second reflux section 34 to the storage section 31 via the second expansion valve 18, and the liquid phase portion of the refrigerant is sent to the compressor 15 through the first reflux section 32.

Second Embodiment
Next, a second embodiment of the present disclosure will be described with reference to Fig. 2. 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. As shown in Fig. 2, in this embodiment, the configuration of the gas-liquid separation mechanism 130 is different from that in the first embodiment. Specifically, the gas-liquid separation mechanism 130 further includes a third reflux section 131 and a second adjustment valve 132 in addition to the components of the gas-liquid separation mechanism 30 in the first embodiment.

The third reflux section 131 connects the storage section 31 and the inlet side of the compressor 15. The third reflux section 131 recovers the gas phase of the refrigerant from the upper part of the storage section 31 and introduces it into the compressor 15. A second adjustment valve 132 is provided in the middle of the third reflux section 131. The second adjustment valve 132 is, for example, a flow rate adjustment valve. By adjusting the opening degree of the second adjustment valve 132, the flow rate of the gas phase of the refrigerant flowing through the third reflux section 131 changes.

(Action and Effect)
According to the above configuration, the gas phase component separated by the gas-liquid separation mechanism 30 is introduced into the compressor 15 through the third reflux section 131. This increases the amount of refrigerant supplied to the compressor 15, making it possible to improve the coefficient of performance (capacity/power consumption) of the air conditioner 1.

Furthermore, according to the above configuration, by adjusting the opening degree of the second adjustment valve 132, the flow rate of the gas phase refrigerant flowing through the third reflux section 131 can be maintained constant at a predetermined value. In addition, the supply of the gas phase refrigerant can be set to zero as necessary. This allows the amount of gas phase refrigerant supplied to the compressor 15 to be optimized according to the operating state. As a result, it becomes possible to operate the air conditioner 1 under a wide range of operating conditions according to the environment and specifications.

The above describes the second embodiment of the present disclosure. Note that various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure. In addition, in the above second embodiment, only the cooling operation of the air conditioner 1 has been described. However, during heating operation, the flow direction of the refrigerant in the first flow path 41 and the second flow path 42, excluding the compressor flow path 43, is reversed. Also, during heating operation, in the gas-liquid separation mechanism 130, the refrigerant flows from the second reflux section 34 into the storage section 31 via the second expansion valve 18, and the liquid phase portion of the refrigerant is sent to the compressor 15 through the first reflux section 32.

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

(1) The air conditioner 1 according to the first aspect includes a compressor 15 that compresses a refrigerant containing refrigerating machine oil, an outdoor heat exchanger 13 that exchanges heat between the refrigerant discharged from the compressor 15 and outside air, a first expansion valve 17 and a second expansion valve 18 that sequentially reduce the pressure of the refrigerant that has passed through the outdoor heat exchanger 13, and an indoor heat exchanger 11 that exchanges heat between the refrigerant that has passed through the expansion valves and outside air and supplies the refrigerant to the compressor 15. The air conditioner 1 further includes a gas-liquid separation mechanism 30 provided between the first expansion valve 17 and the second expansion valve 18. The gas-liquid separation mechanism 30 has a storage section 31 into which the refrigerant that has passed through either the first expansion valve 17 or the second expansion valve 18 is introduced, and a first reflux section 32 that can recover a liquid phase portion from the bottom of the storage section 31 and introduce it into the compressor 15.

According to the above configuration, the liquid phase component separated by the gas-liquid separation mechanism 30 is introduced into the compressor 15 through the first reflux section 32. This allows the refrigeration oil contained in the liquid phase component to function as a lubricant in each part of the compressor 15. As a result, the compressor 15 can be operated more stably.

(2) The air conditioner 1 according to the second aspect is the air conditioner 1 according to (1), in which the gas-liquid separation mechanism 30 is provided in the first reflux section 32 and further includes a first adjustment valve 33 capable of adjusting the flow rate of the liquid phase component.

According to the above configuration, the flow rate of the liquid phase flowing through the first reflux section 32 can be kept constant at a predetermined value by adjusting the opening degree of the first adjustment valve 33. In addition, the supply of the liquid phase can be reduced to zero as necessary. This makes it possible to operate the air conditioner 1 under a wide range of operating conditions according to the environment and specifications.

(3) The air conditioner 1 according to the third aspect is the air conditioner 1 according to (1) or (2), and the gas-liquid separation mechanism 30 further has a second reflux section 34 that can recover the liquid phase from the bottom of the storage section 31 and introduce it into the indoor heat exchanger 11 via the second expansion valve 18.

It is known that when the gas phase of the refrigerant flows through the indoor heat exchanger 11, the pressure loss is greater than that of the liquid phase. With the above configuration, the liquid phase of the refrigerant that has been separated into gas and liquid is introduced into the indoor heat exchanger 11 by the second reflux section 34. This suppresses pressure loss in the indoor heat exchanger 11, making it possible to operate the air conditioner 1 more efficiently.

(4) The air conditioner 1 according to the fourth aspect is an air conditioner 1 according to any one of the aspects (1) to (3), and the gas-liquid separation mechanism 30 further has a third reflux section 131 capable of recovering the gas phase from the upper part of the storage section 31 and introducing it into the compressor 15.

According to the above configuration, the gas phase separated by the gas-liquid separation mechanism 30 is introduced into the compressor 15 through the third reflux section 131. This increases the amount of refrigerant supplied to the compressor 15, making it possible to improve the coefficient of performance (capacity/power consumption) of the air conditioner 1.

(5) The air conditioner 1 according to the fifth aspect is the air conditioner 1 according to (4), in which the gas-liquid separation mechanism 130 is provided in the third reflux section 131 and further includes a second adjustment valve 132 capable of adjusting the flow rate of the gas phase component.

According to the above configuration, the flow rate of the gas phase flowing through the second reflux section 34 can be kept constant at a predetermined value by adjusting the opening degree of the second adjustment valve 132. In addition, the supply of the gas phase can be reduced to zero as necessary. This makes it possible to operate the air conditioner 1 under a wide range of operating conditions according to the environment and specifications.

DESCRIPTION OF SYMBOLS 1...Air conditioner 10...Refrigeration cycle 11...Indoor heat exchanger 12...Indoor fan 13...Outdoor heat exchanger 14...Outdoor fan 15...Compressor 17...First expansion valve 18...Second expansion valve 20...Four-way valve 30...Gas-liquid separation mechanism 31...Storage section 32...First reflux section 33...First adjustment valve 34...Second reflux section 41...First flow path 42...Second flow path 43...Compressor flow path 130...Gas-liquid separation mechanism 131...Third reflux section 132...Second adjustment valve

Claims (5)

A compressor that compresses a refrigerant including refrigeration oil;
an outdoor heat exchanger that exchanges heat between the refrigerant discharged from the compressor and outside air;
a first expansion valve and a second expansion valve which sequentially reduce the pressure of the refrigerant that has passed through the outdoor heat exchanger;
an indoor heat exchanger that exchanges heat between the refrigerant that has passed through either the first expansion valve or the second expansion valve and outside air, and supplies the refrigerant to the compressor;
Equipped with
A gas-liquid separation mechanism is provided between the first expansion valve and the second expansion valve,
The gas-liquid separation mechanism includes:
a storage section into which the refrigerant that has passed through the first expansion valve is introduced;
a first reflux section capable of recovering a liquid phase component from a bottom of the storage section and introducing the liquid phase component into the compressor;
An air conditioner having the above structure. The air conditioner according to claim 1, wherein the gas-liquid separation mechanism further includes a first adjustment valve provided in the first reflux section and capable of adjusting the flow rate of the liquid phase component. The air conditioner according to claim 1 or 2, wherein the gas-liquid separation mechanism further has a second reflux section capable of recovering the liquid phase from the bottom of the storage section and introducing it into the indoor heat exchanger via the second expansion valve. The air conditioner according to claim 1, wherein the gas-liquid separation mechanism further includes a third reflux section capable of recovering the gas phase from the upper part of the storage section and introducing it into the compressor. The air conditioner according to claim 4, wherein the gas-liquid separation mechanism further includes a second adjustment valve provided in the third reflux section and capable of adjusting the flow rate of the gas phase component.

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