JP2006170521A - Refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerator with superior reliability capable of maintaining a refrigerating machine oil amount of each compressor at an optimum state by efficiently discharging excessive portions of refrigerating machine oil in the compressor without being affected by a difference of operation capacities of the compressors, and without deteriorating refrigerant delivery performance. <P>SOLUTION: Refrigerants delivered from the compressors 1a and 1b are joined in a junction pipe 4 via delivery pipes 2a and 2b. Oil pipes 12a and 12b are connected from side parts of sealed cases of the compressors 1a and 1b to the junction pipe 4. The excessive portions of the refrigerating machine oil in the sealed cases are discharged into the oil pipes 12a and 12b, and sucked into the junction pipe 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a refrigeration apparatus including a plurality of compressors.

  The rotary compressor mounted in the refrigeration apparatus is surrounded by a sealed case whose internal space has a high pressure. In the sealed case, refrigeration oil (also referred to as lubricating oil) is accommodated in order to maintain the lubricating action of the components in the sealed case. A part of this refrigeration oil flows out into the refrigeration cycle together with the refrigerant gas discharged from the compressor. The refrigeration oil that has flowed out is circulated through the refrigeration cycle together with the refrigerant and sucked into the compressor.

  In the case of a refrigeration apparatus provided with a plurality of compressors, the amount of refrigeration oil flowing out from each compressor is different for each compressor, and the amount of refrigeration oil returning to each compressor is also different for each compressor. For this reason, a difference arises in the amount of refrigeration oil in the airtight case of each compressor.

  When the amount of the refrigerating machine oil decreases, the lubricating action of the compression mechanism portion in the sealed case cannot be sufficiently maintained.

  When the amount of the refrigerating machine oil increases, the rotor of the motor in the sealed case rotates in the oil, so that the refrigerating machine oil becomes a load and the driving power of the motor increases.

  In view of this, there is a conventional oil return pipe provided between the oil return port provided in each compressor and the discharge pipe of each compressor (Patent Document 1). In this example, the suction pressure is applied to the oil return pipe by the refrigerant flow in the discharge pipe. Due to this suction pressure, surplus refrigeration oil in each compressor flows out to the discharge pipe through the oil return pipe.

Also, pressure loss means is provided in the discharge pipe of each compressor, and an oil discharge pipe is provided between the upper part of the casing of each compressor and the downstream side of the pressure loss means in the discharge pipe of each compressor. There is also (patent document 2). In this example, a pressure difference is generated at both ends of the oil discharge pipe by the pressure loss means in the discharge pipe. Due to this pressure difference, the lubricating oil accumulated on the upper side of the casing of each compressor flows out to the discharge pipe through the oil discharge pipe.
JP 2002-327975 A Japanese Patent No. 3387250

  In the example of Patent Document 1, the magnitude of the suction pressure applied to each oil return pipe corresponds to the discharge refrigerant flow rate for one compressor. For this reason, when a compressor carries out a low capacity | capacitance driving | operation, there exists a possibility that the surplus part of refrigeration oil cannot be discharged efficiently. In addition, when there is a difference in operating capacity between the compressors, the suction pressure applied to the oil return pipe is greatly reduced in the compressor on the low capacity side, whereas the suction pressure applied to the oil return pipe is reduced in the one on the high capacity side compressor. A big rise. For this reason, a big difference may arise in the amount of refrigeration oil in each compressor.

  In the example of Patent Document 2, the magnitude of the suction pressure applied to each oil discharge pipe corresponds to the discharged refrigerant flow rate for one compressor after passing through the pressure loss means. For this reason, as in the example of Patent Document 1, when the compressor is operated at a low capacity, there is a possibility that the refrigeration oil cannot be efficiently discharged. In addition, in this example, since the pressure loss means exists in the discharge pipe, there is a problem that the discharge performance of the refrigerant is deteriorated.

  The present invention takes the above circumstances into consideration, and does not affect the difference in operating capacity between the compressors, and does not deteriorate the discharge performance of the refrigerant, and efficiently drains the excess refrigeration oil in the compressor. Accordingly, an object of the present invention is to provide a highly reliable refrigeration apparatus capable of maintaining the amount of refrigeration oil in each compressor in an optimum state.

  A refrigeration apparatus according to a first aspect of the present invention includes a sealed case in which refrigeration oil is accommodated, a plurality of compressors that suck and compress the refrigerant, and discharge the compressed refrigerant from the discharge port of the sealed case, Connected between a plurality of discharge pipes through which refrigerant discharged from the compressor flows, one merging pipe where the refrigerant in each of the discharge pipes merges, and a side portion of the hermetic case of each compressor and the merging pipe. And a plurality of oil pipes into which surplus refrigeration oil in the sealed case flows.

  According to a third aspect of the present invention, there is provided a refrigeration apparatus including a sealed case in which refrigeration oil is accommodated, a plurality of compressors that suck and compress refrigerant, and discharge the compressed refrigerant from a discharge port of the sealed case; A plurality of discharge pipes through which refrigerant discharged from the compressor flows, one merging pipe in which the refrigerant in each of the discharge pipes merges, and the refrigerant discharged from the merging pipes are passed through an oil separator and an outdoor heat exchanger to the indoor side Are provided with a plurality of outdoor units that guide the refrigerant returning from the indoor side to the suction side of the compressor, from the oil separators of the outdoor units. The first oil pipe connected to the refrigerant suction side of the unit and the second oil pipe connected to the refrigerant suction side of another unit other than the oil separator provided from each oil separator. An oil pipe, and for each of the oil separators The height of the opening position of the serial first oil pipe, than the height of the opening position of the second oil pipe for each oil separator is lowered.

  According to the present invention, it is possible to efficiently drain the excess amount of the refrigeration oil in the compressor without being affected by the difference in operating capacity between the compressors. Thereby, it is possible to provide a refrigeration apparatus with excellent reliability that can maintain the amount of refrigeration oil in each compressor in an optimum state.

[1] A first embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a plurality of outdoor units A1, A2 and a plurality of indoor units B1, B2, B3, B4 are connected to each other by pipes to constitute a multi-type air conditioner.

  In the outdoor unit A1, 1a and 1b are high-pressure rotary compressors in which the space inside the sealed case is filled with high-pressure refrigerant, and the refrigerant is sucked in and compressed, and the compressed refrigerant is discharged from the discharge port of the sealed case. These compressors 1a and 1b are covered with a hermetic case, and refrigeration oil L is accommodated in the hermetic case in order to maintain the lubricating action of each component in the sliding portion of the internal compression mechanism. A part of the refrigerating machine oil L flows out of the sealed case as the refrigerant is discharged.

  The refrigerant discharged from the compressors 1a and 1b (and a part of the refrigerating machine oil L) passes through the discharge pipes 2a and 2b and the check valves 3a and 3b for preventing backflow provided in the discharge pipe 2b. It flows to one junction pipe (high-pressure side pipe) 4. The refrigerant that has flowed to the junction pipe 4 flows to the outdoor heat exchanger 8 through the oil separator 5, the check valve 6, and the four-way valve 7. The oil separator 5 separates and stores the refrigerating machine oil L contained in the refrigerant.

  The refrigerant flowing into the outdoor heat exchanger 8 is liquefied by exchanging heat with the outside air. This liquid refrigerant flows into the plurality of indoor units B1, B2, B3, B4. These indoor units have an expansion valve 31 and an indoor heat exchanger 32. The liquid refrigerant that has flowed to each indoor heat exchanger 32 is gasified by exchanging heat with indoor air. This gas refrigerant returns from each indoor heat exchanger 32 to the outdoor unit A1, and is guided to the suction pipes (low-pressure side pipes) 10a and 10b via the four-way valve 7 and the accumulator 9. The refrigerant guided to the suction pipes 10a and 10b is sucked into the compressors 1a and 1b through gas-liquid separators (also referred to as suction cups) 11a and 11b.

  The outdoor unit A2 has the same configuration, and a heat pump type refrigeration cycle in which the indoor units B1, B2, B3, and B4 are connected to a parallel circuit of the outdoor units A1 and A2 is configured.

  In the outdoor unit A1, one ends of oil pipes 12a and 12b are connected to the side walls of the sealed cases of the compressors 1a and 1b, and the other ends of the oil pipes 12a and 12b are connected to the junction pipe 4. The oil pipes 12a and 12b are provided with check valves 13a and 13b. The check valves 13a and 13b prevent the refrigerant and the refrigerating machine oil L from flowing backward from the merging pipe 4 to the compressors 1a and 1b.

  In the sealed cases of the compressors 1a and 1b, an allowable lower limit position of the oil level of the refrigerating machine oil L is determined in advance. The allowable lower limit position of the oil level corresponds to the minimum amount of refrigeration oil necessary for the operation of the compressors 1a and 1b. The openings of the oil pipes 12a and 12b are provided at positions above the allowable lower limit position of the oil level.

  When the oil level of the refrigerating machine oil L in the sealed case becomes higher than the opening position of the oil pipes 12a and 12b, a mixed fluid having a high refrigerating machine oil ratio flows into the oil pipes 12a and 12b among the mixed fluid of the refrigerating machine oil L and the refrigerant. When the oil level of the refrigerating machine oil L in the sealed case is lower than the opening position of the oil pipes 12a and 12b, a mixed fluid having a high refrigerant gas ratio flows into the oil pipes 12a and 12b among the mixed fluid of the refrigerating machine oil L and the refrigerant gas. To do.

  A first oil pipe 15 for oil return is connected from the bottom of the oil separator 5 to the suction pipes 10a and 10b of the outdoor unit A1 where the oil separator 5 is provided. The oil pipe 15 is provided with an on-off valve 16 and a capillary tube 17 for pressure reduction. Also, second oil pipes 18a and 18b for oil return are connected from the bottom of the oil separator 5 to the suction pipes 10a and 10b of the outdoor unit A2 different from the outdoor unit A1 where the oil separator 15 is provided. Has been. The oil pipe 18a is provided with an on-off valve 19 for controlling the supply of refrigeration oil from the outdoor unit A1 to the outdoor unit A2. The oil pipe 18b is provided with an on-off valve 20 for controlling the intake of the refrigeration oil from the outdoor unit A2.

  About the opening position of the oil pipes 15 and 18a with respect to the oil separator 5, the opening position of the oil pipe 18a is set higher than the height of the opening position of the oil pipe 15. All the refrigerating machine oil L accommodated in the oil separator 5 can flow into the oil pipe 15, and the refrigerating machine oil L existing above the opening position of the oil pipe 18a flows into the oil pipe 18a.

  Similarly, the outdoor unit A2 is provided with oil pipes 12a and 12b, check valves 13a and 13b, an oil pipe 15, an on-off valve 16, and a capillary tube 17.

  In the outdoor unit A2, an oil pipe 15 for oil return is connected from the bottom of the oil separator 5 to the suction pipes 10a and 10b of the outdoor unit A2 where the oil separator 5 is provided. The oil pipe 15 is provided with an on-off valve 16 and a capillary tube 17 for pressure reduction. Also, oil return oil pipes 18a and 18b are connected from the bottom of the oil separator 5 to the suction pipes 10a and 10b of the outdoor unit A1 different from the outdoor unit A2 in which the oil separator 15 is provided. Yes. The oil pipe 18a is provided with an on-off valve 19 for controlling the supply of refrigeration oil from the outdoor unit A2 to the outdoor unit A1. The oil pipe 18b is provided with an on-off valve 20 for controlling the intake of the refrigerating machine oil from the outdoor unit A1.

  About the opening position of the oil pipes 15 and 18a with respect to the oil separator 5, the opening position of the oil pipe 18a is set higher than the height of the opening position of the oil pipe 15. All the refrigerating machine oil L accommodated in the oil separator 5 can flow into the oil pipe 15, and the refrigerating machine oil L existing above the opening position of the oil pipe 18a flows into the oil pipe 18a.

The operation will be described.
When the compressors 1a and 1b are operated, the refrigerant discharged from the compressors 1a and 1b joins the merge pipe 4 through the discharge pipes 2a and 2b. The speed of the merged refrigerant is higher than the speed of the refrigerant passing through each of the discharge pipes 2a and 2b. Due to this fast merging refrigerant, suction pressure (negative pressure) is applied from the merging pipe 4 to the oil pipes 12a and 12b.

  Moreover, the internal pressure of each sealed case is increased by the operation of the compressors 1a and 1b. If the oil level of the refrigerating machine oil L accommodated in the sealed case of the compressor 1b is higher than the opening position of the oil pipe 12b, the refrigerating machine oil L that exceeds the opening position flows into the oil pipe 12b as a surplus. . The refrigeration oil L that has flowed in is sucked into the merging pipe 4 in response to the suction pressure from the merging pipe 4.

  If the oil level of the refrigerating machine oil L accommodated in the sealed case of the compressor 1a is higher than the opening position of the oil pipe 12a, the refrigerating machine oil L that exceeds the opening position flows into the oil pipe 12a as a surplus. . The refrigeration oil L that has flowed in is sucked into the merging pipe 4 in response to the suction pressure from the merging pipe 4.

  The magnitude of the suction pressure applied from the merging pipe 4 to the oil pipes 12a and 12b corresponds to the discharge refrigerant flow rate for two compressors. Therefore, even when one of the compressors 1a and 1b is operated at a low capacity, the suction pressure applied from the merging pipe 4 to the oil pipes 12a and 12b has a sufficient magnitude, and the excess of the refrigerating machine oil L of the compressors 1a and 1b. The minute can be efficiently discharged toward the junction pipe 4. The surplus portion of the refrigerating machine oil L that has flowed into the merge pipe 4 is sucked into the compressors 1a and 1b through the refrigerating cycle.

  Even if there is a difference in operating capacity between the compressors 1a and 1b, the suction pressure applied from the merging pipe 4 to the oil pipes 2a and 2b is the same. Therefore, even if there is a difference in the operating capabilities of the compressors 1a and 1b, there is no significant difference in the amount of the refrigerating machine oil L in the compressors 1a and 1b.

  As described above, the suction pressure is applied to the oil pipes 12a and 12b by the merged refrigerant in the merged pipe 4 corresponding to the flow rate of the refrigerant discharged from the two compressors, thereby being affected by the difference in the operating capacity of the compressors 1a and 1b. Without surplus, the excess of the refrigerating machine oil L in the compressors 1a and 1b can be efficiently discharged. Thereby, the amount of refrigerating machine oil of compressor 1a, 1b can be maintained in the optimal state, and the reliability as a refrigerating device improves significantly. Since the suction pressure can be secured without providing pressure loss means in the discharge pipe as in the prior art, the refrigerant discharge performance does not deteriorate.

  On the other hand, the merged refrigerant in the merge tube 4 flows to the oil separator 5. The refrigerant that has flowed to the oil separator 5 contains the refrigerating machine oil L discharged from the compressors 1a and 1b. This refrigerating machine oil L accumulates in the oil separator 5.

  In the outdoor unit A1, when the on-off valve 16 is opened, the refrigerating machine oil L accumulated in the oil separator 5 flows into the suction pipes 10a, 10b through the oil pipe 15, the on-off valve 16, and the capillary tube 17. The refrigerating machine oil L flowing into the suction pipes 10a and 10b is sucked into the compressors 1a and 1b.

  When the opening / closing valve 19 of the outdoor unit A1 is opened and the opening / closing valve 20 of the outdoor unit A2 is opened, the refrigerating machine oil L accumulated in the oil separator 5 of the outdoor unit A1 passes through the oil pipe 18a and the opening / closing valve 19. Furthermore, it flows through the oil pipe 18b on the outdoor unit A2 side and the open / close valve 20 to the suction pipes 10a and 10b of the outdoor unit A2. The refrigerating machine oil L that has flowed into the suction pipes 10a and 10b is sucked into the compressors 1a and 1b of the outdoor unit A2. That is, the refrigerating machine oil L on the outdoor unit A1 side can be supplied to the outdoor unit A2 in response to a request from the outdoor unit A2.

  When the on-off valve 19 of the outdoor unit A2 is opened and the on-off valve 20 of the outdoor unit A1 is opened, the refrigerating machine oil L accumulated in the oil separator 5 of the outdoor unit A2 passes through the oil pipe 18a and the on-off valve 19. Furthermore, the oil flows through the oil pipe 18b on the outdoor unit A1 side and the on-off valve 20 to the suction pipes 10a and 10b of the outdoor unit A1. The refrigerating machine oil L that has flowed into the suction pipes 10a and 10b is sucked into the compressors 1a and 1b of the outdoor unit A1. That is, the refrigerating machine oil L on the outdoor unit A2 side can be supplied to the outdoor unit A1 in response to a request from the outdoor unit A1.

  About the opening position of the oil pipes 15 and 18a with respect to the oil separator 5, the height of the opening position of the oil pipe 15 for own unit replenishment is set lower than the height of the opening position of the oil pipe 18a for other unit replenishment. .

  Therefore, even if the refrigerating machine oil L in the oil separator 5 of the outdoor unit A1 is replenished to the outdoor unit A2, the replenishment amount of the refrigerating machine oil L to the outdoor unit A1 is stored in the oil separator 5 of the outdoor unit A1. Secured surely. Thereby, the shortage of refrigeration oil in outdoor unit A1 can be prevented.

  Similarly, even if the refrigerating machine oil L in the oil separator 5 of the outdoor unit A2 is supplied to the outdoor unit A1, the oil separator 5 of the outdoor unit A2 has a replenishment amount of the refrigerating machine oil L to its outdoor unit A2. , Ensured. Thereby, the shortage of refrigeration oil in outdoor unit A2 can be prevented.

[2] A second embodiment will be described.
As shown in FIG. 2, the merging pipe 4 is provided with a negative pressure suction mechanism 40. Then, one end of each of the oil pipes 12a and 12b is connected to the negative pressure suction mechanism 40 in an inclined state.

  As shown in FIG. 3, the negative pressure suction mechanism 40 is provided so as to cover the merging pipe 4, and the tips of the oil pipes 12 a and 12 b are coupled to the merging pipe 4 while holding the oil pipes 12 a and 12 b in an inclined state. It has a configuration. The inclination of the oil pipes 12a and 12b with respect to the merging pipe 4 is inclined at an acute angle toward the upstream side of the flow of the refrigerating machine oil L.

With the configuration in which the oil pipes 12a and 12b are coupled to the joining pipe 4 in an inclined state, the suction pressure (negative pressure) generated by the refrigerant flow in the joining pipe 4 is efficiently and smoothly applied to the oil pipes 12a and 12b. Therefore, the surplus of the refrigerating machine oil L in the compressors 1a and 1b can be discharged more efficiently.
Other configurations and operational effects are the same as those of the first embodiment. Therefore, the description is omitted.

[3] A third embodiment will be described.
As shown in FIG. 4, the communication pipe 52a is connected between the upstream position of the check valve 13a in the oil pipe 12a and the suction pipe 10a through which the suction refrigerant of the compressor 1a flows, via a decompression means such as a capillary tube 51a. It is connected. And the temperature sensor 53a is attached to the downstream position of the capillary tube 51a in the communicating pipe 52a.

  A communication pipe 52b is connected between the upstream position of the check valve 13b in the oil pipe 12b and the suction pipe 10b through which the suction refrigerant of the compressor 1b flows, via a decompression means, for example, a capillary tube 51b. And the temperature sensor 53b is attached to the downstream position of the capillary tube 51b in the communicating pipe 52b.

  The temperature sensors 53 a and 53 b are connected to the control unit 60. Inverters 61 a and 61 b are connected to the control unit 60.

Inverters 61a and 61b convert the voltage of commercial AC power supply 62 into a DC voltage, convert the DC voltage into an AC voltage having a frequency corresponding to a command from control unit 60 by switching, and output the voltage. The motors (compressor motors) Ma and Mb of the compressors 1a and 1b are driven by this output. When the output frequencies of the inverters 61a and 61b change, the capabilities of the compressors 1a and 1b change.
In addition, the structure of the refrigerating cycle of FIG. 4 has shown only the principal part of FIG.

The control unit 60 has the following means (1) to (3) as main functions.
(1) First determination means for determining whether the fluid flowing through the communication pipes 52a and 52b is the refrigerating machine oil L or the refrigerant according to the detected temperatures T1 and T2 of the temperature sensors 53a and 53b.

  (2) Second determination means for determining whether the amount of refrigerating machine oil of the compressors 1a and 1b is appropriate or insufficient according to the determination result of the first determination means.

  (3) Control means for executing a so-called oil leveling operation that averages the amount of the refrigerating machine oil L in the compressors 1a and 1b when the second determination means determines that the shortage has occurred. The oil leveling operation is, for example, an operation that alternately increases or decreases the capacity of the compressors 1a and 1b (output frequencies of the inverters 61a and 61b).

The operation will be described.
When the oil level of the refrigerating machine oil L in the sealed case is higher than the opening position of the oil pipes 12a and 12b, a mixed fluid having a high refrigerating machine oil ratio flows into the oil pipes 12a and 12b among the mixed fluid of the refrigerating machine oil L and the refrigerant. . When the oil level of the refrigerating machine oil L in the sealed case is lower than the opening position of the oil pipes 12a and 12b, a mixed fluid having a high refrigerant gas ratio flows into the oil pipes 12a and 12b among the mixed fluid of the refrigerating machine oil L and the refrigerant gas. To do.

Part of the fluid (refrigerator oil L or refrigerant) flowing into the oil pipes 12a and 12b flows to the suction pipes 10a and 10b via the communication pipes 52a and 52b and the capillary tubes 51a and 51b. At this time, the temperatures Ta and Tb of the fluid flowing through the communication pipes 52a and 52b are detected by the temperature sensors 53a and 53b, respectively.
When the fluid level is higher than the opening position of the oil pipe 12a and a mixed fluid having a high refrigerating machine oil ratio flows through the communication pipe 52a, the detection temperature Ta of the temperature sensor 53a becomes relatively high. When the fluid level is lower than the opening position of the oil pipe 12a and a mixed fluid having a high refrigerant gas ratio flows through the communication pipe 52a, the detection temperature Ta of the temperature sensor 53a is relatively low.

  When the detected temperature Ta of the temperature sensor 53a is equal to or higher than the set value, it is determined that the fluid flowing through the communication pipe 52a is the refrigerating machine oil L. And based on this determination, it determines with the amount of refrigerating machine oil of the compressor 1a being appropriate. When the detected temperature Ta of the temperature sensor 53a is less than the set value, it is determined that the fluid flowing through the communication pipe 52a is a refrigerant. Based on this determination, it is determined that the amount of refrigeration oil in the compressor 1a is insufficient.

  Similarly, when the fluid level is higher than the opening position of the oil pipe 12b and a mixed fluid having a high refrigerating machine oil ratio flows through the communication pipe 52b, the detected temperature Tb of the temperature sensor 53b becomes relatively high. When the fluid level is lower than the opening position of the oil pipe 12b and a mixed fluid having a high refrigerant gas ratio flows through the communication pipe 52b, the temperature Tb detected by the temperature sensor 53b is relatively low.

  When the detected temperature Tb of the temperature sensor 53b is equal to or higher than the set value, it is determined that the fluid flowing through the communication pipe 52b is the refrigerating machine oil L. And based on this determination, it determines with the amount of refrigeration oil of the compressor 1b being appropriate. When the detected temperature Tb of the temperature sensor 53b is less than the set value, it is determined that the fluid flowing through the communication pipe 52b is a refrigerant. Based on this determination, it is determined that the amount of refrigeration oil in the compressor 1b is insufficient.

  When it is determined that one of the compressors 1a and 1b is insufficient in the amount of the refrigerating machine oil, an oil equalizing operation for averaging the amount of the refrigerating machine oil L in the compressors 1a and 1b is executed, for example, for a predetermined time. This oil leveling operation solves the shortage of the oil amount of the compressors 1a and 1b.

  Other configurations and operational effects are the same as those of the first embodiment. Therefore, the description is omitted.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine the component covering different embodiment suitably.

The figure which shows the structure of 1st Embodiment. The figure which shows the structure of 2nd Embodiment. The figure which shows the structure of the principal part in 2nd Embodiment. The figure which shows the structure of the principal part of 3rd Embodiment.

Explanation of symbols

  A1, A2 ... outdoor unit, B1-B4 ... indoor unit, 1a, 1b ... compressor, 2a, 2b ... discharge pipe, 4 ... confluence pipe, 5 ... oil separator, 8 ... outdoor heat exchanger, 10a, 10b ... Suction pipe, 12a, 12b ... oil pipe, 15 ... first oil pipe, 18a, 18b ... second oil pipe, L ... refrigerator oil, 32 ... indoor heat exchanger, 40 ... negative pressure suction mechanism, 52a, 52b ... communication pipe, 53a , 53b ... temperature sensor, 60 ... control unit, 61a, 61b ... inverter

Claims (3)

A plurality of compressors having a sealed case containing refrigeration oil, sucking and compressing the refrigerant, and discharging the compressed refrigerant from a discharge port of the sealed case;
A plurality of discharge pipes through which refrigerant discharged from each compressor flows;
One merge pipe where the refrigerant in each discharge pipe merges;
A plurality of oil pipes connected between a side portion of the hermetic case of each compressor and the merging pipe, and into which surplus refrigeration oil in the hermetic case flows;
A refrigeration apparatus comprising: A plurality of communication pipes connected via decompression means between each oil pipe and a suction pipe through which the suction refrigerant of each compressor flows;
First determination means for determining whether the fluid flowing through each of the communication pipes is refrigeration oil or refrigerant;
Second determination means for determining whether the amount of refrigerating machine oil of each compressor is appropriate or insufficient according to the determination result of the first determination means;
The refrigeration apparatus according to claim 1, further comprising: A plurality of compressors having a sealed case containing refrigeration oil, sucking and compressing the refrigerant, and discharging the compressed refrigerant from a discharge port of the sealed case;
A plurality of discharge pipes through which refrigerant discharged from each compressor flows;
One merge pipe where the refrigerant in each discharge pipe merges;
In the refrigeration apparatus comprising a plurality of outdoor units that supply the refrigerant discharged from the junction pipe to the indoor side through the oil separator and the outdoor heat exchanger and guide the refrigerant returning from the indoor side to the suction side of the compressor,
From the oil separator of each outdoor unit to the refrigerant suction side of the unit where the oil separator is provided, the connected first oil pipe,
From each of the oil separators to the refrigerant suction side of another unit other than the oil separators provided, the second oil pipe connected,
And the height of the opening position of the first oil pipe with respect to each oil separator is made lower than the height of the opening position of the second oil pipe with respect to each oil separator.

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