JP2011064429A - Refrigerating device for transportation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating device for transportation, which surely eliminates such a problem that an amount of lubricating oil of a compressor having no oil reservoir is insufficient in the refrigerating device for transportation wherein the compressor having no oil reservoir and a compressor having the oil reservoir are connected in parallel with each other and one of the compressors is operated individually. <P>SOLUTION: In the refrigerating device 1 for transportation, a mist lubricating type first compressor 3 having no oil reservoir and a forced lubrication type second compressor 4 having the oil reservoir are connected in parallel with each other in a refrigerant circuit 2, and the first compressor 3 and the second compressor 4 are respectively operated individually. An oil separator 8 is disposed on a downstream side of a merging part 7 into which the delivery pipes 5 and 6 of the first compressor 3 and the second compressor 4 are merged, an oil return circuit 18 is provided for returning the oil from the oil separator 8 to at least the first compressor 3 side, and a solenoid valve 20 opened only when the first compressor 3 is operated is provided in the oil return circuit 18. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a transportation refrigeration apparatus configured such that two compressors are connected in parallel to a refrigerant circuit, and either one of the compressors is operated alone.

  As a transport refrigeration system mounted on a refrigeration vehicle or the like, two refrigerant driving circuits, an engine-driven main compressor driven by a traveling engine, and a motor-driven standby compressor driven by a commercial power source A transport refrigeration apparatus is known which is connected in parallel and is capable of operating each compressor individually. In such a transport refrigeration system, a mist-lubricated compressor without an oil reservoir that can be reduced in size is adopted as the engine-driven main compressor, while the motor-driven standby compressor has a reliable lubrication performance. Some compressors employ a forced lubrication type compressor with an oil sump that is easy to ensure.

  This refrigeration system is operated using an engine-driven main compressor when the traveling engine is driven, and is a standby compression driven by a commercial power source when the vehicle is stopped and the engine is stopped. Since the oil circulation rate (OC%) of each compressor is different, the amount of lubricating oil circulated in the refrigerant circuit is “when the main compressor is operated> standby compressor. When operating the standby compressor after operating the engine-driven main compressor, the lubricating oil circulated in the refrigerant circuit is collected in the oil reservoir of the standby compressor, However, when the main compressor is operated, there is a problem that the amount of lubricating oil may be insufficient.

  In order to solve this problem, a plurality of U-shaped refrigerant outflow pipes having oil return holes are provided in the accumulator installed on the suction pipe side of the compressor, and the oil return holes have different heights corresponding to each compressor. The difference between the amount of lubricating oil circulated to the refrigerant circuit side during operation of the main compressor and the amount of lubricating oil circulated to the refrigerant circuit side during operation of the standby compressor in the accumulator Japanese Patent Application Laid-Open No. H10-228688 discloses a configuration in which the shortage of lubricating oil during operation of the main compressor is resolved by accumulating oil.

  In Patent Document 2, one of the two compressors connected in parallel is a compressor having an oil sump, and the other one is a compressor without an oil sump. In an engine-driven heat pump with an oil separator in the discharge line, even when both compressors are driven at the same time, the amount of lubricating oil returned to the compressor without an oil reservoir is not reduced. In addition to the main oil return pipe, a compressor having no oil sump provided with an oil return line for returning oil via an on-off valve is proposed.

Japanese Patent Laying-Open No. 2009-8361 (see FIGS. 1 and 2) JP 2006-250435 A (see FIGS. 1 and 2)

However, the one disclosed in Patent Document 1 requires that at least two U-shaped refrigerant outflow pipes configured by a pipe having a large diameter be provided in the accumulator, so that the accumulator itself becomes large and the pipe configuration There is a problem that becomes complicated and becomes a cost increase factor.
In addition, what is disclosed in Patent Document 2 is provided with two systems of oil return lines so that when two compressors are operated at the same time, there is not a shortage of lubricating oil returned to the compressor without an oil sump. This not only complicates the circuit configuration but also requires an oil separator with a large capacity, and when a compressor having an oil sump is operated alone, the lubricating oil is recovered in the sump, and thereafter When a compressor without an oil reservoir is operated alone, it cannot be a solution for the problem that the amount of lubricating oil is insufficient.

  This invention is made | formed in view of such a situation, Comprising: The compressor without an oil sump and the compressor which has an oil sump are connected in parallel, and either compressor is operated independently. It is an object of the present invention to provide a transport refrigeration apparatus that can reliably eliminate a situation in which the amount of lubricating oil in a compressor that does not have an oil sump falls short.

In order to solve the above-described problems, the transport refrigeration apparatus of the present invention employs the following means.
That is, in the transport refrigeration apparatus according to the present invention, a mist lubrication type first compressor having no oil sump and a forced lubrication type second compressor having an oil sump are connected in parallel to the refrigerant circuit. In the transport refrigeration apparatus configured such that each of the first compressor and the second compressor is independently operated, a junction where discharge pipes of the first compressor and the second compressor are merged An oil separator is installed downstream of the oil separator, an oil return circuit capable of returning oil from the oil separator to at least the first compressor side is provided, and the first compressor is provided in the oil return circuit. An electromagnetic valve that is opened only during operation is provided.

A mist lubrication type first compressor having no oil sump in the refrigerant circuit and a forced lubrication type second compressor having an oil sump are connected in parallel so that one of the compressors is operated alone. In the transport refrigeration apparatus configured as described above, when the first compressor is operated alone and then the second compressor is operated alone, the lubricating oil staying in the refrigerant circuit is stored in the oil reservoir of the second compressor. It will be collected inside and held inside. For this reason, when the first compressor is operated next, there is a problem that the amount of the lubricating oil may be insufficient.
According to the present invention, the oil separator is installed on the downstream side of the junction where the discharge pipes of the first compressor and the second compressor are merged, and the oil can be returned from the oil separator to at least the first compressor. The oil return circuit is provided, and the oil return circuit is provided with a solenoid valve that is opened only when the first compressor is in operation. Therefore, the second compressor is operated alone. In the meantime, the amount of lubricating oil circulated in the refrigerant circuit when the first compressor is operated alone in the oil separator, and is circulated in the refrigerant circuit when the second compressor is operated alone. The amount of lubricating oil corresponding to the difference from the amount of lubricating oil can be separated and held. When the first compressor is operated, the lubricating oil is fed to the first compressor side via the oil return circuit and the electromagnetic valve. It can be returned and circulated in the refrigerant circuit. Therefore, even when the first compressor is operated after the second compressor is operated, it is possible to ensure a certain amount of lubricating oil or more, and to eliminate the situation where the lubricating oil amount falls short. it can. Further, when the first compressor is stopped, the solenoid valve is closed and the oil return to the suction side of the first compressor is blocked, so that oil compression at the time of restart can be prevented. As a result, the reliability with respect to each compressor operation can be improved.

  Further, the transport refrigeration apparatus of the present invention is the transport refrigeration apparatus, wherein the oil separator includes at least the amount of lubricating oil circulated in the refrigerant circuit when the first compressor is operated alone, The second compressor has a capacity capable of separating and holding the amount of lubricating oil corresponding to the difference from the amount of lubricating oil circulated in the refrigerant circuit when the second compressor is operated alone.

  According to the present invention, the oil separator is at least circulated in the refrigerant circuit when the first compressor is operated alone, and the amount of lubricating oil circulated in the refrigerant circuit when the second compressor is operated alone. Since the amount of lubricating oil corresponding to the difference from the amount of lubricating oil to be separated is separated and held, the oil separator has at least the capacity of the second compressor while it is operating alone. This corresponds to the difference between the amount of lubricating oil circulated in the refrigerant circuit when the first compressor is operated alone and the amount of lubricating oil circulated in the refrigerant circuit when the second compressor is operated alone. A quantity of lubricating oil can be separated and held. Therefore, even if the first compressor is operated after the second compressor is operated independently, the lubricating oil held in the oil separator is returned to the first compressor side through the oil return circuit and the electromagnetic valve, and the refrigerant circuit. Since it can be made to circulate in, the situation where the amount of lubricating oil in the first compressor falls short is surely eliminated.

  Furthermore, in the transport refrigeration apparatus of the present invention, in any one of the transport refrigeration apparatuses described above, the oil separator is at least with respect to the amount of lubricating oil circulated to the refrigerant circuit side during operation of the first compressor. It is characterized by having a capacity capable of holding about half of the amount of lubricating oil.

  According to the present invention, the oil separator is configured to have a capacity capable of holding approximately half of the amount of lubricating oil with respect to the amount of lubricating oil circulated to the refrigerant circuit side during operation of the first compressor. Therefore, from the oil circulation rate (OC%) of the first compressor, when the amount of lubricating oil circulated to the refrigerant circuit side during the operation of the first compressor is, for example, about 600 ml, approximately half that amount By providing an oil separator having a capacity of about 300 ml, the amount of lubricating oil required for the first compressor during operation can be secured. Therefore, when the first compressor is operated, it is possible to surely eliminate the situation where the amount of lubricating oil falls short, and it is not necessary to provide a large oil separator. Can be improved.

  Furthermore, in the transport refrigeration apparatus according to the present invention, in any one of the transport refrigeration apparatuses described above, the refrigerant suction pipe of the second compressor has a second electromagnetic that is closed while the second compressor is stopped. A valve is provided.

  According to the present invention, since the refrigerant suction pipe of the second compressor is provided with the second electromagnetic valve that is closed while the second compressor is stopped, the first compressor is operated. By closing the refrigerant suction pipe on the second compressor side being stopped by the second solenoid valve, the lubricating oil moves to the second compressor side little by little through the refrigerant suction pipe and accumulates. Can be prevented. Therefore, there is no fear that the lubricating oil will move excessively to the second compressor side, and even if the first compressor continues to operate for a long time, it is possible to reliably eliminate the situation where the amount of lubricating oil falls short. it can.

  Furthermore, in the transport refrigeration apparatus according to the present invention, in any of the transport refrigeration apparatuses described above, the first compressor is an engine-driven main compressor driven by a traveling engine, and the second compressor Is a motor-driven standby compressor driven by a commercial power source.

  According to the present invention, the first compressor is an engine-driven main compressor driven by a traveling engine, and the second compressor is a motor-driven standby compressor driven by a commercial power source. Therefore, it is possible to make the first compressor of the main compressor and the second compressor of the standby compressor a compressor suitable for being driven by a traveling engine and a commercial power source that are respective drive sources. In other words, the first compressor driven by the traveling engine is a mist lubricated compact compressor that does not have an oil sump, so that it can be mounted in a narrow engine room and lubricated. Can be increased. On the other hand, since the motor-driven second compressor driven by a commercial power source is a forced lubrication type compressor having an oil sump, the reliability of the lubrication performance can be ensured. Reliability can be improved.

  According to the present invention, while the second compressor having the oil sump is operated alone, the first compressor without the oil sump in the oil separator is circulated in the refrigerant circuit when operated alone. The amount of lubricating oil corresponding to the difference between the amount of lubricating oil and the amount of lubricating oil circulated in the refrigerant circuit when the second compressor is operated alone can be separated and held. When the first compressor is operated, it can be returned to the first compressor side through the oil return circuit and the solenoid valve, and can be circulated in the refrigerant circuit. Therefore, the first compressor is operated after the second compressor is operated. Even when the operation is performed, a certain amount or more of the lubricating oil amount can be ensured, and the situation where the lubricating oil amount falls short can be solved. Further, when the first compressor is stopped, the solenoid valve is closed and the oil return to the suction side of the first compressor is blocked, so that oil compression at the time of restart can be prevented. As a result, the reliability with respect to each compressor operation can be improved.

It is a refrigerant circuit figure at the time of operation of the 1st compressor (main compressor) of the refrigeration equipment for transportation concerning one embodiment of the present invention. FIG. 3 is a refrigerant circuit diagram when the second compressor (standby compressor) of the transport refrigeration apparatus shown in FIG. 1 is in operation.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 shows a refrigerant circuit diagram when the first compressor (main compressor) of the transport refrigeration apparatus according to one embodiment of the present invention is in operation, and FIG. 2 shows the second compressor (standby). The refrigerant circuit diagram when the compressor for operation is in operation is shown.
The transport refrigeration apparatus 1 is a refrigeration apparatus that is mounted on a refrigeration vehicle or the like and is used for cooling and cold storage in a freezer. The refrigerant circuit 2 includes two first compressors 3 and a second compression. Machines 4 are connected in parallel.

  The refrigerant circuit 2 is composed of two first and second compressors 3 and 4 connected in parallel and a junction 7 where discharge pipes 5 and 6 of the first and second compressors 3 and 4 are joined. An oil separator 8 installed on the downstream side, a condenser 9 for condensing and liquefying the high-pressure refrigerant gas, an expansion valve 10 for adiabatic expansion of the liquid refrigerant, and an evaporator 11 for evaporating and gasifying the adiabatically expanded refrigerant are sequentially refrigerant piping. 12 is connected. The refrigerant pipe 12 connected to the outlet of the evaporator 11 is branched into two, which are refrigerant intake pipes 13 and 14 respectively connected to the first and second compressors 3 and 4.

  The discharge pipes 5 and 6 are provided with check valves 15 and 16, respectively, and the refrigerant suction pipe 14 to the second compressor 4 is opened while the second compressor 4 is being driven. A second electromagnetic valve 17 is provided that is closed when the compressor 2 is stopped. Further, one end of an oil return circuit 18 is connected to the oil separator 8, and the other end is connected to the refrigerant pipe 12 immediately upstream where the refrigerant suction pipes 13 and 14 are branched. The oil return circuit 18 is provided with a capillary tube 19 that adjusts the amount of oil returned, and an electromagnetic valve 20 that is opened only when the first compressor 3 is being driven.

  The first compressor 3 is a mist lubrication type compressor having no oil sump, and is configured to be installed in an engine room of a refrigerated vehicle and driven by an engine for driving the vehicle via an electromagnetic clutch. ing. The first compressor 3 is a main compressor of the transport refrigeration apparatus 1, and the transport refrigeration apparatus 1 is operated by driving the first compressor 3 while the refrigeration vehicle is running (the engine is operating). It has come to be.

  On the other hand, the second compressor 4 is a forced lubrication type compressor having an oil sump, and is mounted under the chassis of the refrigeration vehicle. The second compressor 4 is a motor-driven compressor that is driven by a commercial power source, and is driven using the commercial power source as a drive source when the cooling operation is performed with the refrigeration vehicle stopped and the engine stopped. It is considered as a standby compressor.

  The first compressor 3 as the main compressor and the second compressor 4 as the standby compressor are not operated at the same time, and either one is operated independently. While the compressor 3 is in operation, the solenoid valve 20 in the oil return circuit 18 is opened, and the second solenoid valve 17 in the refrigerant suction pipe 14 is closed. Conversely, while the second compressor 4 is in operation, the electromagnetic valve 20 in the oil return circuit 18 is closed, and the second electromagnetic valve 17 in the refrigerant suction pipe 14 is opened.

The oil separator 8 may have any structure, and for example, a centrifugal oil separator can be used. The oil separator 8 may have a relatively small oil reservoir capacity, and the capacity is set as follows.
The first compressor 3 of the mist lubrication system having no oil reservoir has a large oil circulation rate (OC%) of the lubricating oil discharged from the compressor to the refrigerant circuit 2 side, while the forced lubrication system has an oil reservoir. The second compressor 4 has a low oil circulation rate (OC%). The capacity of the oil separator 8 is a capacity capable of separating and holding the amount of lubricating oil corresponding to the difference in the amount of lubricating oil due to the difference in the oil circulation rate (OC%).

  Specifically, the first compressor 3 has a capacity capable of holding at least about half of the amount of lubricating oil circulated to the refrigerant circuit 2 side during operation. For example, from the oil circulation rate (OC%) of the first compressor 3, when the amount of lubricating oil circulated to the refrigerant circuit 2 side during the operation of the first compressor 3 is about 600 ml, about half that amount The oil separator 8 has a capacity of about 300 ml.

  In the transport refrigeration apparatus 1, during operation of the first compressor 3 that is the main compressor, the refrigerant gas compressed by the first compressor 3 is discharged from a discharge pipe 5 as indicated by a solid arrow in FIG. 1. Then, the oil is discharged to the oil separator 8 through the check valve 15, where the lubricating oil in the gas is separated and then supplied to the condenser 9, where it is condensed and liquefied by heat exchange with the outside air. This refrigerant is adiabatically expanded by the expansion valve 10, then supplied to the evaporator 11, and evaporated by exchanging heat with the air in the freezer. Thereby, the air circulated from the inside of the freezer is cooled and used for cooling inside the refrigerator. The refrigerant gasified by the evaporator 11 is sucked into the first compressor 3 through the refrigerant suction pipe 13 and compressed again. The inside of the freezer is cooled by repeating the above operation.

  During this time, the lubricating oil separated by the oil separator 8 is returned to the refrigerant suction pipe 13 through the oil return circuit 18 in which the solenoid valve 20 is opened, and the flow rate is adjusted by the capillary tube 19, and is accompanied by the refrigerant gas. And sucked into the first compressor 3. While the first compressor 3 of the mist lubrication system is in operation, the oil circulation rate (OC%) is high and the amount of the lubricating oil separated by the oil separator 8 increases accordingly. The refrigerant circulates in the refrigerant circuit 2 through the circuit 18 and becomes oil droplets together with the refrigerant gas to mist lubricate the sliding portion of the first compressor 3.

  During operation of the first compressor 3, the second electromagnetic valve 17 provided in the refrigerant suction pipe 14 to the second compressor 4 is closed, and therefore the lubrication circulated to the refrigerant circuit 2 side. The oil is not moved to the second compressor 4 side through the refrigerant suction pipe 14, and therefore, the lubricating oil is stored in the oil reservoir of the second compressor 4, and the oil on the first compressor 3 side is stored. It is possible to prevent a situation in which the amount of lubricating oil is insufficient.

  On the other hand, during operation of the second compressor 4 that is a standby compressor, the refrigerant compressed by the second compressor 4 is discharged into the discharge pipe 6 and the check valve 16 as shown by solid arrows in FIG. Then, the oil is discharged to the oil separator 8 where the lubricating oil contained in the gas is separated. The second compressor 4 is a forced lubrication type compressor having an oil sump, and has a low oil circulation rate (OC%) and a small amount of lubricating oil to be separated, but the electromagnetic valve 20 in the oil return circuit 18 is closed. Thus, the separated lubricating oil is held in the oil separator 8 by a certain amount as it is.

  When a certain amount of lubricating oil is accumulated in the oil separator 8, thereafter, a small amount of lubricating oil is not separated by the oil separator 8 but is circulated in the refrigerant circuit 2 along with the refrigerant gas. . Then, when the refrigerant gas is cooled through the condenser 9, the expansion valve 10, and the evaporator 11 as described above, and is sucked into the second compressor 4 through the refrigerant suction pipe 14, the refrigerant gas is sent to the second compressor 4 together with the refrigerant gas. And a small amount of lubricating oil commensurate with the oil circulation rate (OC%) is circulated in the refrigerant circuit 2.

  However, according to the present embodiment, the discharge pipes 5 and 6 of the first compressor 3 of the mist lubrication type that does not have an oil sump and the second compressor 4 for standby of the forced lubrication type that has an oil sump are joined. An oil separator 8 having a predetermined capacity is installed on the downstream side of the merging portion 7, and an oil return circuit 18 capable of returning oil from the oil separator 8 to at least the first compressor 3 is provided. The circuit 18 is provided with a solenoid valve 20 that is opened only when the first compressor 3 is in operation. Therefore, the amount of lubricating oil circulated in the refrigerant circuit 2 when the first compressor 3 is operated alone in the oil separator 8 while the second compressor 4 for standby is being operated, and the second The amount of lubricating oil corresponding to the difference from the amount of lubricating oil circulated in the refrigerant circuit 2 when the compressor 4 is operated alone can be separated and held.

The lubricating oil held in the oil separator 8 is returned to the first compressor 3 side via the oil return circuit 18 and the electromagnetic valve 20 when the first compressor 3 as the main compressor is operated. The refrigerant circuit 2 can be circulated.
Therefore, even when the first compressor 3 as the main compressor is operated after the standby second compressor 4 is operated, it is possible to always ensure a certain amount of lubricating oil, and the amount of lubricating oil is insufficient. The situation that falls into the mood can be resolved. Further, when the first compressor 3 is stopped, the solenoid valve 20 is closed and the oil return to the suction side of the first compressor 3 is blocked, so that oil compression at the time of restart can be prevented. . As a result, the reliability with respect to each compressor operation can be improved.

  Further, the oil separator 8 includes the amount of lubricating oil circulated in the refrigerant circuit 2 when the first compressor 3 as the main compressor is operated alone, and the standby second compressor 4 is operated alone. A configuration having a capacity capable of separating and holding the amount of lubricating oil corresponding to the difference from the amount of lubricating oil circulated in the refrigerant circuit 2 sometimes, specifically, the refrigerant circuit 2 while the first compressor 3 is in operation. When the amount of lubricating oil circulated to the side is about 600 ml, for example, the oil separator 8 has a capacity capable of holding about 300 ml of lubricating oil, which is approximately half of that amount. During operation, the amount of lubricating oil circulated in the refrigerant circuit 2 when at least the first compressor 3 is operated alone in the oil separator 8 and when the second compressor 4 is operated alone. Moisture circulated in the refrigerant circuit 2 The amount of lubricating oil corresponding to the difference between the amount of oil can be separated and held.

  Thus, even if the first compressor 3 as the main compressor is operated after the standby second compressor 4 is operated independently, the lubricating oil held in the oil separator 8 is removed from the oil return circuit 18 and Since it can return to the 1st compressor 3 side via the solenoid valve 20 and it can circulate through the refrigerant circuit 2, the situation where the amount of lubricating oil of the 1st compressor 3 falls short is surely eliminated. . In addition, it is not necessary to provide a large oil separator 8, and the transport refrigeration apparatus 1 can be made compact and the mounting property on a vehicle can be improved.

  In addition, the second suction valve 14 of the standby second compressor 4 is provided with a second electromagnetic valve 17 that is closed while the second compressor 4 is stopped, and the first compressor 3 that is the main compressor is in operation. Since the refrigerant suction pipe 14 on the second compressor 4 side that is stopped is closed by the second electromagnetic valve 17, the lubricating oil is minutely passed through the refrigerant suction pipe 14 on the second compressor 4 side. It is possible to prevent the oil from being stored in the oil sump. Therefore, there is no fear that the lubricating oil will move excessively to the stopped second compressor 4 side, and even if the main first compressor 3 is operated for a long time, the amount of lubricating oil falls short. Can be solved reliably.

  Further, since the first compressor 3 is an engine-driven main compressor driven by a traveling engine and the second compressor 5 is a motor-driven standby compressor driven by a commercial power source, the first compressor 3 The first compressor 3 and the second compressor 4 of the standby compressor can be optimal compressors that are driven by a traveling engine and a commercial power source, which are the respective drive sources. In other words, since the first compressor 3 driven by the traveling engine is a compact compressor of a mist lubrication system that does not have an oil sump, it can be mounted in a narrow engine room and lubricated. Since the motor-driven second compressor 4 driven by a commercial power source is a forced lubrication type compressor having an oil sump, the reliability of the lubrication performance can be ensured. Become. As a result, the reliability of each compressor operation can be improved.

  In addition, this invention is not limited to the invention concerning the said embodiment, In the range which does not deviate from the summary, it can change suitably. For example, in the above embodiment, the oil return circuit 18 is connected to the refrigerant pipe 12 immediately upstream from which the refrigerant suction pipes 13 and 14 to the first and second compressors 3 and 4 are branched. Of course, the return circuit 18 may be connected to the refrigerant suction pipe 13 to the first compressor 3.

  The compression mechanisms of the first compressor and the second compressors 3 and 4 may be any type of compression mechanism, and the motor-driven standby second compressor driven by a commercial power source is a motor. Either a compressor with a built-in motor or a compressor driven by an external motor may be used.

1 Refrigeration equipment for transportation 2 Refrigerant circuit 3 First compressor (main compressor)
4 Second compressor (standby compressor)
5, 6 Discharge piping 7 Junction 8 Oil separators 13, 14 Refrigerant suction piping 17 Second solenoid valve 18 Oil return circuit 20 Solenoid valve

Claims (5)

A mist lubrication type first compressor having no oil sump and a forced lubrication type second compressor having an oil sump are connected in parallel to the refrigerant circuit, and the first compressor and the second compressor are connected to each other in parallel. In the transport refrigeration apparatus configured to be operated independently,
An oil separator is installed on the downstream side of the junction where the discharge pipes of the first compressor and the second compressor are merged,
An oil return circuit capable of returning oil from the oil separator to at least the first compressor side is provided, and an electromagnetic valve opened only during operation of the first compressor is provided in the oil return circuit. A transport refrigeration apparatus characterized by being provided.   The oil separator includes at least an amount of lubricating oil circulated in the refrigerant circuit when the first compressor is operated alone, and lubrication circulated in the refrigerant circuit when the second compressor is operated alone. The transport refrigeration apparatus according to claim 1, wherein the transport refrigeration apparatus has a capacity capable of separating and holding an amount of lubricating oil corresponding to a difference from the oil amount.   The oil separator has a capacity capable of holding approximately half the amount of lubricating oil with respect to the amount of lubricating oil circulated to the refrigerant circuit side during operation of the first compressor. The transport refrigeration apparatus according to claim 1 or 2.   The refrigerant suction pipe of the second compressor is provided with a second electromagnetic valve that is closed when the second compressor is stopped. Refrigeration equipment for transportation. The first compressor is an engine driven main compressor driven by a traveling engine, and the second compressor is a motor driven standby compressor driven by a commercial power source. The transport refrigeration apparatus according to any one of claims 1 to 4.

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