JP2017089988A - Refrigerant circuit of air conditioner, and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure of an air conditioner capable of improving lubricity in starting, and suppressing oil compression in a mist lubrication type compressor.SOLUTION: An oil separation portion 3 for separating an oil O from a refrigerant R including the oil O discharged from a compressor 10, has a first oil separator 11 of a small oil holding capacity, connected to a discharge-side flow channel 10a of the compressor 10, and separating the oil O from the refrigerant R, a first oil return flow channel 13 capable of allowing the oil O separated by the first oil separator 11, to flow into a suction-side flow channel 10b of the compressor 10, a second oil separator 12 having larger oil holding capacity in comparison with the first oil separator 11, and disposed between the first oil separator 11 and a condenser 4 in series with the first oil separator 11, and a second oil return flow channel 14 capable of allowing the oil separated by the second oil separator 12 to flow into a gas-liquid separating portion 8 in a refrigerant circuit 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a refrigerant circuit of an air conditioner and an air conditioner.

  For example, a vehicle air conditioner such as a transport refrigerator is generally equipped with a compressor that compresses refrigerant gas in the engine room of the vehicle. However, since the installation space is small, it is transported to the refrigerant without an oil pan. It is common to use a compressor lubricated with mist oil.

  By the way, in the transport refrigerator, the temperature adjustment range in the warehouse is wide, and a large heat exchanger is installed to ensure the refrigeration capacity in a low temperature region. Furthermore, since the compressor is driven by the power of the engine of the vehicle, the drive rotational speed of the compressor changes greatly depending on the vehicle operating state (engine speed, etc.), and the flow rate of the refrigerant in the refrigerant circuit also changes. As the refrigerant flow rate slows down, the amount of oil held in the refrigerant circuit increases. As a result, for example, there is a problem that the heat exchange performance in the heat exchanger in the refrigerant circuit is lowered and the amount of oil supplied to the compressor is lowered, resulting in insufficient lubrication.

  With respect to such a problem, Patent Document 1 describes that an oil separator is provided in a refrigerant circulation circuit to solve an oil shortage in a compressor.

Japanese Patent Laid-Open No. 6-26714

  However, as in Patent Document 1, when an oil separator is provided so that separated oil flows into the flow path on the suction side of the compressor, it is held in the refrigerant circuit when the refrigerant is operated at a high refrigerant flow rate. The amount of oil to be reduced decreases, and the amount of oil retained in the oil separator increases. If the operation of the compressor is stopped from this state, a large amount of oil in the oil separator moves to the flow path on the suction side, and there is a possibility that oil compression occurs when the operation of the compressor is resumed.

  The present invention has been made in order to solve the above-described problem, and provides an air conditioner refrigerant circuit and an air conditioner that can suppress oil compression while avoiding a shortage of the amount of oil supplied to the compressor. provide.

In order to solve the above problems, the present invention proposes the following means.
The refrigerant circuit of the air conditioner according to the first aspect of the present invention includes heat exchange between an oil separation unit that separates oil from a refrigerant that includes oil discharged from a compressor, and the refrigerant from the oil separation unit. A condenser that condenses the refrigerant by performing a decompression, a decompressor that decompresses the refrigerant from the condenser, an evaporator that evaporates the refrigerant from the decompressor, and a gas phase and a liquid phase in the refrigerant from the evaporator And a gas-liquid separator that allows the gas phase to flow into the compressor, and the oil separator is connected to a discharge-side flow path of the compressor and separates oil from the refrigerant. One oil separator, a first oil return passage that allows oil separated by the first oil separator to flow into a suction side passage of the compressor, and a larger oil holding capacity than the first oil separator, And the first oil separator is in series with the first oil separator. It has a second oil separator provided between the separator and the condenser, and the second oil return passage to the oil separated by the second oil separator can flow into the gas-liquid separator, a.

According to such a refrigerant circuit, the first oil separator having a smaller oil holding capacity than the second oil separator is provided, and the oil is returned from the first oil separator to the suction side flow path of the compressor. For this reason, the amount of oil separated and retained by the first oil separator can be kept low, and a large amount of oil that moves to the suction-side flow path after the operation is stopped does not flow into the compressor. Oil compression can be suppressed. Further, by connecting the second oil separator having a larger oil holding capacity than the first oil separator to the first oil separator, the oil that cannot be held by the first oil separator can be held by the second oil separator. Therefore, it is possible to suppress an increase in the amount of oil held in the refrigerant circuit, and to reduce the oil circulation ratio (OCR) in the refrigerant circuit.
Moreover, since the oil hold | maintained by the 2nd oil separator flows in into a gas-liquid separation part, it can avoid flowing into a compressor and causing oil compression. Moreover, since it becomes possible to return oil to a gas-liquid separation part from a 2nd oil separator, the oil shortage in a refrigerant circuit can be avoided.
Furthermore, the oil from the first oil separator having a small oil holding capacity flows into the suction side flow path of the compressor. For this reason, a small amount of oil from the first oil separator flows into the compressor when the air conditioner is started, and the oil can flow into the compressor in a short time after the start. Therefore, it is possible to suppress poor lubrication in the compressor at the time of startup.

  Moreover, in the refrigerant circuit of the air conditioner according to the second aspect of the present invention, the flow resistance of the oil in the first oil return channel in the first aspect is larger than that in the second oil return channel. Set.

  As described above, the flow resistance of the oil in the first oil return flow path is larger than that in the second oil return flow path, thereby limiting the flow rate of the oil flowing into the compressor from the first oil separator, and the normal operation range. The oil can be stored inside the first oil separator over the entire area. As a result, every time after the operation is stopped, the suction-side flow path is filled with oil, and the oil can be supplied in a short time when the compressor is started.

  Moreover, in the refrigerant circuit of the air conditioner according to the third aspect of the present invention, between the oil separation unit that separates oil from the refrigerant containing oil discharged from the compressor, and the refrigerant from the oil separation unit A condenser that performs heat exchange to condense the refrigerant, a decompressor that decompresses the refrigerant from the condenser, an evaporator that evaporates the refrigerant from the decompressor, and a gas phase in the refrigerant from the evaporator; A gas-liquid separation unit for separating the liquid phase and then allowing the gas phase to flow into the compressor, and the oil separation unit is connected to a discharge-side flow path of the compressor to separate oil from the refrigerant The first oil separator, the first oil return channel that allows the oil separated by the first oil separator to flow into the suction side channel of the compressor, and the oil holding capacity that is higher than that of the first oil separator. Large and in series with the first oil separator A second oil separator provided between the one oil separator and the condenser; a second oil return channel that allows oil separated by the second oil separator to flow into the suction side channel; And a valve device that is provided in the two oil return channel and opens and closes the second oil return channel.

According to such a refrigerant circuit, the first oil separator having a small oil holding capacity is provided, and the oil is returned from the first oil separator to the suction side passage of the compressor. For this reason, the amount of oil separated and retained by the first oil separator can be kept low, and a large amount of oil that moves to the suction-side flow path after the operation is stopped does not flow into the compressor. Oil compression can be suppressed. Furthermore, by connecting a second oil separator, which has a larger oil holding capacity than the first oil separator, between the first oil separator and the condenser, oil that cannot be retained by the first oil separator is second oil. Can be separated with a separator. Therefore, the oil circulation rate (OCR) in the refrigerant circuit can be reduced.
Further, when the operation is stopped, the valve device is closed, so that the oil is held in the second oil separator, and oil compression due to movement of a large amount of oil to the suction side flow path can be prevented.

  In the refrigerant circuit of the air conditioner according to the fourth aspect of the present invention, the flow resistance of the oil in the first oil return passage in the third aspect is at least one in the operating range in which the operation of the device is ensured. Part of oil is set to a value that can be held in the first oil separator.

  Thus, by defining the flow resistance of the oil in the first oil return channel, the oil can be stored inside the first oil separator in the operation range that ensures the operation of the device. As a result, the suction-side flow path is filled with oil every time after the operation is stopped, and the compressor can be supplied with oil in a short time after startup.

  An air conditioner according to a fifth aspect of the present invention includes a compressor that compresses a refrigerant containing oil, and the refrigerant circuit connected to the compressor, the compressor, and the first The oil separator is provided in an engine room of the transportation vehicle, and the second oil separator, the condenser, the decompressor, the evaporator, and the gas-liquid separator are provided in a transportation container of the transportation vehicle. It may be provided.

According to such an air conditioner, by providing the first oil separator having a small oil holding capacity in the refrigerant circuit, it is possible to suppress the oil held by the first oil separator from flowing into the compressor. Furthermore, by connecting the second oil separator having a large oil holding capacity to the first oil separator, the oil that cannot be held by the first oil separator can be separated by the second oil separator. Therefore, the oil circulation rate (OCR) in the refrigerant circuit can be reduced.
Furthermore, since the oil from the first oil separator with a small oil holding capacity flows into the suction side passage of the compressor, the oil flows into the compressor in a short time after the air conditioner is started. Therefore, poor lubrication in the compressor at startup can be suppressed.
In addition, by providing the first oil separator in the engine room in this way, the first oil separator can be installed near the compressor. Therefore, it becomes easy to flow the oil from the first oil separator into the compressor, and poor lubrication in the compressor can be suppressed.

  According to the air conditioner refrigerant circuit and the air conditioner described above, by providing the first oil separator and the second oil separator, it is possible to suppress oil compression while avoiding a shortage of oil supplied to the compressor. It becomes.

1 is an overall configuration diagram of an air conditioner according to a first embodiment of the present invention. It is a schematic whole view of the transport vehicle by which the air conditioner which concerns on 2nd embodiment of this invention is mounted. It is a whole block diagram of the air conditioner which concerns on 2nd embodiment of this invention. It is a whole block diagram of the air conditioner which concerns on 3rd embodiment of this invention.

[First embodiment]
Hereinafter, the air conditioner 1 in 1st embodiment of this invention is demonstrated.
As shown in FIG. 1, the air conditioner 1 of the present embodiment circulates the compressor 10 that compresses the refrigerant R containing the oil O and the refrigerant R that is discharged from the compressor 10, and the compressor 10 again. And a refrigerant circuit 2 for supplying the refrigerant.

  The compressor 10 compresses a low-pressure gaseous refrigerant R (hereinafter, refrigerant gas G) and discharges a high-temperature and high-pressure refrigerant gas G. In the compressor 10, lubrication is performed using the oil O (mist oil) contained in the refrigerant R as the refrigerant R is compressed. An example of the compressor 10 is a scroll type compressor. Further, the compressor 10 is provided with a discharge-side flow path 10a on the discharge side and a suction-side flow path 10b on the suction side.

  The refrigerant circuit 2 includes an oil separator 3 connected to the discharge-side flow path 10a of the compressor 10, a condenser 4, a receiver tank 5 connected in order from the oil separator 3 toward the downstream side where the refrigerant R flows, A decompressor 6, an evaporator 7, and a gas-liquid separator 8 are provided.

  The oil separator 3 introduces a high-temperature and high-pressure refrigerant gas G containing oil O discharged from the compressor 10 through a discharge-side flow path 10 a provided in the compressor 10, and separates the oil O from the refrigerant gas G. Then, a part of the oil O is held at the same time as being supplied to the suction side flow path 10b.

  The condenser 4 is an outdoor heat exchanger that introduces the high-temperature / high-pressure refrigerant gas G from the oil separation unit 3, and performs heat exchange with the high-temperature / high-pressure refrigerant gas G, so that the refrigerant gas G Heat is radiated to the outside, and the refrigerant gas G is condensed to form a high-pressure liquid refrigerant R (refrigerant liquid L).

  The receiver tank 5 introduces the high-pressure refrigerant liquid L from the condenser 4, stores excess refrigerant liquid L, and separates gas components contained in the refrigerant liquid L.

  The decompressor 6 is, for example, an expansion valve or the like, and introduces the high-pressure refrigerant liquid L after removing the gas component from the receiver tank 5 and decompresses the refrigerant liquid L to obtain the low-pressure refrigerant liquid L. .

  The evaporator 7 is an indoor heat exchanger that introduces the low-pressure refrigerant gas G from the decompressor 6. The evaporator 7 absorbs heat from the low-pressure refrigerant liquid L to evaporate the refrigerant liquid L, thereby forming the low-pressure refrigerant gas G.

  The gas-liquid separator 8 is a so-called accumulator, which introduces the low-pressure refrigerant gas G from the evaporator 7 and separates the refrigerant gas G into a gas phase Ra and a liquid phase Rl, and then converts the gas phase Ra into a compressor. 10 is introduced into the suction side flow passage 10b.

  In the refrigerant circuit 2, the oil separator 3, the condenser 4, the receiver tank 5, the decompressor 6, the evaporator 7, and the gas-liquid separator 8 are connected to each other via a pipeline 15.

Next, the oil separation unit 3 will be described in detail.
The oil separator 3 includes a first oil separator 11 connected to the discharge-side flow path 10a of the compressor 10, a second oil separator 12 provided between the first oil separator 11 and the condenser 4, A first oil return channel 13 provided in one oil separator 11 and a second oil return channel 14 provided in the second oil separator 12 are provided.

  The first oil separator 11 separates the oil O from the refrigerant gas G discharged from the compressor 10 and supplies the oil O to the suction side flow path 10b, while holding a part of the oil O.

  The first oil return channel 13 connects the first oil separator 11 and the suction side channel 10b. The connection position of the first oil return channel 13 to the suction side channel 10 b is a midway position between the compressor 10 and the gas-liquid separator 8. And the oil O hold | maintained at the 1st oil separator 11 flows in into the suction side flow path 10b of the compressor 10 via the 1st oil return flow path 13. As shown in FIG.

  Further, the flow resistance of the oil O in the first oil return flow path 13 is an operating range that ensures the operation of the device, and all of the oil O held by the first oil separator 11 flows out toward the suction side flow path 10b. It is set to a value that will not be lost.

  Further, a capillary tube or the like can be applied to the first oil return channel 13 in order to set the flow resistance value in the first oil return channel 13 to a predetermined value.

  The second oil separator 12 is provided in series with the first oil separator 11 on the downstream side of the refrigerant flow with respect to the first oil separator 11. When the second oil separator 12 separates the oil O in the refrigerant gas G from the first oil separator 11 (the amount of oil O that cannot be separated by the first oil separator 11) and supplies the oil O to the suction side flow path 10b. Hold some oil at the same time.

  The second oil return channel 14 connects the second oil separator 12 and the gas-liquid separator 8. Further, the second oil return channel 14 allows the oil O held in the second oil separator 12 to flow into the gas-liquid separation unit 8. Furthermore, in this embodiment, the flow resistance of the oil O in the first oil return channel 13 is larger than that in the second oil return channel 14.

  Thus, in order to set the value of the flow resistance in the second oil return channel 14 to a predetermined value, a capillary tube or the like is applied to the second oil return channel 14 in the same manner as the first oil return channel 13. Is possible.

  In the air conditioner 1 of the present embodiment described above, since the refrigerant circuit 2 is provided, the first oil separator 11 having a small oil O holding capacity is used to start with the refrigerant gas G from the compressor 10. The oil O is separated and held. The oil O is returned from the first oil separator 11 to the suction side passage 10b of the compressor 10 by the first oil return passage 13. For this reason, the amount of the oil O separated and held by the first oil separator 11 can be kept low, and a large amount of the oil O moving to the suction side flow path 10b after the operation is stopped does not flow into the compressor 10. Therefore, oil compression when restarting operation can be suppressed.

  Furthermore, by connecting the second oil separator 12 having a larger oil O holding capacity than the first oil separator 11 to the downstream side of the first oil separator 11, the oil that cannot be separated and held by the first oil separator 11. O can be separated and held by the second oil separator 12. Therefore, an increase in the amount of oil O held in the refrigerant circuit 2 can be suppressed, and the circulation rate (OCR) of the oil O in the refrigerant circuit 2 can be reduced.

  The second oil separator 12 can hold more oil O than the first oil separator 11, but the held oil O flows into the gas-liquid separation unit 8, so the second oil separator Therefore, the oil O does not flow directly into the compressor 10 from 12, and the compressor 10 can be prevented from causing oil compression.

  Further, since the oil O can be returned from the second oil separator 12 to the gas-liquid separator 8, a shortage of the oil O in the refrigerant circuit 2 can be avoided.

  Further, the oil O from the first oil separator 11 having a small oil O holding capacity flows into the suction-side flow path 10b after the operation is stopped. For this reason, before the compressor 10 starts operation, the suction-side flow path 10b is filled with oil, and the oil O can be flowed into the compressor 10 in a short time after startup. That is, it is possible to suppress occurrence of a time lag until the oil O from the gas-liquid separation unit 8 reaches the compressor 10 at the time of startup.

  Therefore, according to the air conditioner 1 of the present embodiment, it is possible to suppress oil compression while avoiding a shortage of the amount of oil O in the compressor 10.

In addition, the first oil return channel 13 is set to have a larger flow resistance of the oil O than the second oil return channel 14, so that the first oil separator 11 is spread over the entire operation range in which the operation of the device is ensured. Oil O can be stored inside As a result, the suction-side flow path 10b is filled with oil every time after the operation is stopped, and the oil O can be supplied in a short time when the compressor 10 is started.
Further, the flow resistance of the oil O in the first oil return passage 13 is defined, and at least the oil O is supplied to the first oil separator 11 with the circulation amount of the oil O in the operation range that ensures the operation of the equipment as described above. By holding a part, it is possible to prevent the entire amount of oil O from flowing into the compressor 10 from the first oil separator 11. Therefore, the occurrence of oil compression in the compressor can be suppressed.

  In the present embodiment, the retention capacity of the oil O in the first oil separator 11 is preferably about ½ or less of the suction side volume of the compression mechanism portion of the compressor 10.

  In the present embodiment, the holding capacity of the oil O in the second oil separator 12 is larger than the holding capacity of the oil O in the first oil separator 11. Here, the retention capacity (separation performance) of the oil O may be a capacity such that the circulation rate (OCR) of the oil O in the refrigerant circuit 2 is approximately 2 [weight percent] or less. In this case, the circulation rate (OCR) of the oil O in the refrigerant circuit 2 can be kept at a sufficiently low value, the amount of the oil O held in the refrigerant circuit 2 can be further suppressed, and the heat exchange performance Improvement will increase cooling capacity.

[Second Embodiment]
Next, with reference to FIG.2 and FIG.3, the air conditioner 21 in 2nd embodiment of this invention is demonstrated.
The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
The air conditioner 21 of the present embodiment is different from the first embodiment in that the air conditioner 21 is a transport refrigerator mounted on the transport vehicle 100.

  As shown in FIG. 2, the transportation vehicle 100 on which the air conditioner 21 of the present embodiment is mounted includes a vehicle main body 101 and a loading platform 102 provided on the vehicle main body 101.

  As shown in FIG. 3, the compressor 10 and the first oil separator 11 in the air conditioner 21 are provided in the engine room ES of the vehicle main body 101 on which the engine 103 is mounted. And is driven by its power.

  The second oil separator 12, the condenser 4, the receiver tank 5, the decompressor 6, the evaporator 7, and the gas-liquid separator 8 are housed inside the refrigerator main body 110, attached to the cargo bed 102, and installed inside the cargo bed 102. Cool the space.

  In the air conditioner 21 of the present embodiment described above, similarly to the first embodiment, by providing the first oil separator 11 and the second oil separator 12, the shortage of the amount of oil O in the compressor 10 is avoided. However, oil compression can be suppressed.

  Further, in the present embodiment, the first oil separator 11 can be installed near the compressor 10. Therefore, the oil O from the first oil separator 11 can easily flow into the compressor 10, and poor lubrication in the compressor 10 can be suppressed.

  Further, in the engine room ES with a small installation space, only the compressor 10 and the first oil separator 11 of the air conditioner 21 are installed, and the rest is attached to the loading platform 102. For this reason, the installation space of the 2nd oil separator 12, the condenser 4, the receiver tank 5, the decompressor 6, the evaporator 7, and the gas-liquid separation part 8 with a large capacity | capacitance can be ensured.

[Third embodiment]
Next, with reference to FIG. 4, the air conditioner 31 in 3rd embodiment of this invention is demonstrated.
The same components as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
In the air conditioner 31 of this embodiment, the connection position in the refrigerant circuit 2 of the 2nd oil return flow path 14 differs from 1st embodiment and 2nd embodiment.

  That is, the second oil return flow path 34 is connected to the suction side flow path 10b on the upstream side of the flow of the refrigerant R from the position where the first oil return flow path 13 is connected to the suction side flow path 10b. Thus, the second oil separator 12 and the suction-side flow path 10b are communicated with each other.

  In addition, since the value of the flow resistance of the oil O is set to a predetermined value, a capillary tube or the like can be applied to the second oil return channel 34 of the present embodiment as in the first embodiment and the second embodiment. .

  The air conditioner 31 of this embodiment further includes a valve device 35 that is provided in the second oil return channel 34 and opens and closes the second oil return channel 34. The opening / closing operation may be performed by a control unit (not shown) using the valve device 35 as an electromagnetic valve, or the opening / closing operation of the valve device 35 may be performed manually.

  In the air conditioner 31 of this embodiment described above, the oil O in the compressor 10 is provided by providing the first oil separator 11 and the second oil separator 12 as in the first embodiment and the second embodiment. The occurrence of oil compression can be suppressed while avoiding the shortage of the amount.

Furthermore, in the present embodiment, by providing the valve device 35, the oil O can be held on the second oil separator 12 side by closing the second oil return channel 34 while the operation is stopped.
As a result, there is no movement of oil to the suction side flow path 10b (low pressure side flow path), and oil compression can be prevented in advance.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations of the embodiments in the embodiments are examples, and the addition and omission of configurations are within the scope not departing from the gist of the present invention. , Substitutions, and other changes are possible. Further, the present invention is not limited by the embodiments, and is limited only by the scope of the claims.

  For example, the first oil separator 11 has a capacity that does not cause oil compression in the compressor 10 even if the entire amount flows out to the compressor 10 in addition to having a smaller oil holding capacity than the second oil separator 12. Good.

1 ... Air conditioner
2 ... Refrigerant circuit
3 ... Oil separation part
4 ... Condenser
5 ... Receiver tank
6 ... decompressor
7 ... Evaporator
8 ... Gas-liquid separation part
10 ... Compressor
10a ... discharge side channel 10b ... suction side channel 11 ... first oil separator
12 ... Second oil separator
13 ... First oil return channel
14 ... Second oil return passage
15 ... pipeline
21 ... Air conditioner
31 ... Air conditioner
34 ... Second oil return passage
35 ... Valve device
DESCRIPTION OF SYMBOLS 100 ... Transportation vehicle 101 ... Vehicle main body
102 ... loading platform
103 ... Engine
110 ... Refrigerator body
ES ... Engine room
R: Refrigerant
O ... oil
G: Refrigerant gas
L: Refrigerant liquid
Ra ... gas phase
Rl ... Liquid phase

Claims (5)

An oil separator that separates oil from a refrigerant containing oil discharged from the compressor;
A condenser that performs heat exchange with the refrigerant from the oil separation unit to condense the refrigerant;
A decompressor for decompressing the refrigerant from the condenser;
An evaporator for evaporating the refrigerant from the decompressor;
A gas-liquid separation unit for separating the gas phase and the liquid phase in the refrigerant from the evaporator and then flowing the gas phase into the compressor;
With
The oil separator is
A first oil separator connected to the discharge side flow path of the compressor and separating oil from the refrigerant;
A first oil return channel that allows oil separated by the first oil separator to flow into a suction side channel of the compressor;
A second oil separator provided between the first oil separator and the condenser so as to have a larger oil holding capacity than the first oil separator, and in series with the first oil separator;
A second oil return channel that allows oil separated by the second oil separator to flow into the gas-liquid separation unit;
A refrigerant circuit for an air conditioner.   The refrigerant circuit of the air conditioner according to claim 1, wherein the first oil return channel has a larger oil flow resistance than the second oil return channel. An oil separator that separates oil from a refrigerant containing oil discharged from the compressor;
A condenser that performs heat exchange with the refrigerant from the oil separation unit to condense the refrigerant;
A decompressor for decompressing the refrigerant from the condenser;
An evaporator for evaporating the refrigerant from the decompressor;
A gas-liquid separation unit for separating the gas phase and the liquid phase in the refrigerant from the evaporator and then flowing the gas phase into the compressor;
With
The oil separator is
A first oil separator connected to the discharge side flow path of the compressor and separating oil from the refrigerant;
A first oil return channel that allows oil separated by the first oil separator to flow into a suction side channel of the compressor;
A second oil separator provided between the first oil separator and the condenser so as to have a larger oil holding capacity than the first oil separator, and in series with the first oil separator;
A second oil return channel that allows oil separated by the second oil separator to flow into the suction side channel;
A valve device provided in the second oil return channel to open and close the second oil return channel;
A refrigerant circuit for an air conditioner.   The oil flow resistance in the first oil return flow path is set to a value that allows at least a part of the oil to be retained in the first oil separator in an operation range in which the operation of the device is ensured. The refrigerant circuit of the air conditioner described. A compressor for compressing a refrigerant containing oil;
The refrigerant circuit according to any one of claims 1 to 4 connected to the compressor;
With
The compressor and the first oil separator are provided in an engine room of a vehicle for transportation,
The second oil separator, the condenser, the decompressor, the evaporator, and the gas-liquid separator are an air conditioner provided in a transport container of the transport vehicle.

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