JP2011202860A - Refrigerating device and oil amount management method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily determine whether or not an oil amount is proper in a refrigerating device carrying out parallel piping connection to a user side apparatus of a plurality of refrigerator units.SOLUTION: In the refrigerating device 1 having two refrigerator units respectively mounted with a compressor, sight glasses 17 for oil level confirmation are provided in oil separators 12, 22 provided in each unit, and inter-unit oil recovery piping is provided, including a valve device communicating an oil outlet of one oil separator with a suction side of the other compressor. A controller has an inter-unit oil recovery mode opening the valve device of one of the refrigerator units on the basis of a predetermined command, and operating the compressor in each refrigerator unit.

Description

  The present invention relates to a refrigeration apparatus in which a plurality of refrigeration unit units are connected in parallel to a use side device, and more particularly to oil amount management of the refrigeration unit.

  In general, use side devices such as multiple showcases are connected in parallel, and multiple refrigerator units with built-in compressors and heat exchangers are connected in parallel to the inter-unit piping connected to each showcase. A so-called multi refrigerator is known (see, for example, Patent Document 1).

  Each refrigeration unit includes a compressor, a condenser, and the like, and each usage-side device includes a throttle means, an evaporator, and the like, and a refrigeration cycle is configured by connecting these by piping. The refrigerant compressed by the compressor dissipates heat by the condenser and is depressurized by the throttling means. Then, the refrigerant is evaporated by the evaporator, and the ambient air is cooled by evaporation of the refrigerant at this time.

JP 2002-206812 A

  On the other hand, since the refrigeration unit requires oil as a circulating agent in operation of a compressor or the like, a predetermined amount of oil is enclosed in the refrigerant pipe together with the refrigerant. If the amount of oil is less than the appropriate amount, the lubrication and sealing performance of the sliding portion of the compressor will decrease, leading to mechanical deterioration of the compressor. On the other hand, if the amount is larger than the appropriate amount, a large amount of oil flows into the use side device, leading to a decrease in cooling capacity.

  The appropriate amount of oil varies depending on the number of usage-side devices and the length of the refrigerant pipes connecting these to each refrigeration unit. Therefore, conventionally, an appropriate amount of oil corresponding to the site is calculated in advance in consideration of the number of usage-side devices installed and the length of the refrigerant piping, and the amount of oil is enclosed in the refrigerant piping.

  However, when a refrigerant leak or the like subsequently occurs, an oil leak occurs as in the refrigerant. Therefore, when the refrigerant is re-enclosed, it is necessary to return the leaked oil to an appropriate amount. In addition, when the number of installed devices on the use side and the pipe length are changed, the appropriate amount of oil is also changed, so that it is necessary to replenish and extract oil according to the change in the installation status.

  In this case, using a sight glass for confirming the oil amount provided in the refrigeration unit or the refrigerant pipe, it is determined whether or not the oil amount is appropriate visually. However, in the multi-refrigerator as described above, oil is accumulated excessively in one refrigeration unit, and in other refrigeration unit, when the oil is insufficient, the refrigeration apparatus as a whole has an appropriate amount of oil. It was difficult to determine if there was any.

  The present invention has been made to solve the conventional technical problem, and is configured to connect a plurality of refrigerator units in parallel to a user side device and easily determine whether the amount of oil is appropriate. A refrigeration apparatus that makes it possible to make a determination is provided.

  In order to solve the above problems, a refrigeration apparatus according to the present invention comprises at least two refrigeration unit units each equipped with a compressor connected in parallel to a user side device, An oil separator provided in each unit for separating the oil discharged from the compressor of the refrigerator unit and returning it to the compressor, and provided in each oil separator for checking the oil level in the oil separator The oil recovery pipe between the units that communicates the sight glass with the oil outlet of the oil separator of one refrigerator unit and the suction side of the compressor of the other refrigerator unit, and the oil circulation of the oil recovery pipe between the units. A control valve device, and a control device for controlling the valve device. Opening the valve device of one of the refrigeration unit Zui, characterized by having a unit between oil recovery mode for driving the compressor of the refrigerator unit.

  The invention of claim 2 is characterized in that, in the above, the control device has a test operation mode in which the valve device is closed and the compressor of each refrigerator unit is operated at the maximum capacity.

  The invention of claim 3 is characterized in that, in each of the above inventions, the control device operates the compressor of each refrigerator unit with the maximum capacity in the inter-unit oil recovery mode.

  According to a fourth aspect of the present invention, in the above inventions, when the oil level cannot be confirmed with the sight glass of all the refrigerator units, any one of the refrigerator units is set to the inter-unit oil recovery mode by the control device, and then the refrigerator When the oil level can be confirmed with the sight glass of the unit, the inter-unit oil recovery mode is terminated, and when the oil level cannot be confirmed, oil is added to the refrigerator unit.

  According to a fifth aspect of the present invention, in the above-mentioned invention, before the execution of the inter-unit oil recovery mode, the control device closes the valve device to execute the test operation mode in which the compressors of the respective refrigerator units are operated at the maximum capacity, The oil level is checked with the sight glass of the machine unit.

  According to the present invention, in a refrigeration apparatus in which at least two refrigeration units each having a compressor mounted thereon are connected in parallel to a user side device, each refrigeration unit is provided with each refrigeration unit. An oil separator for separating the oil discharged from the compressor and returning it to the compressor, a sight glass for checking the oil level in each oil separator, and one of the refrigerator units An oil recovery pipe between units that communicates the oil outlet of the oil separator and the suction side of the compressor of the other refrigerator unit, a valve device that controls the flow of oil in the oil recovery pipe between the units, and this valve device And a control device that controls either of the refrigerator units based on a predetermined command. The oil recovery pipe between units is opened by performing the oil recovery mode between units by opening the valve device of the engine and operating the compressor of each refrigerator unit. Through this, oil can be recovered in the oil separator of any of the refrigerator units.

  Accordingly, it is possible to easily determine whether or not the amount of oil in the entire refrigeration apparatus is an appropriate amount by confirming the oil level in the oil separator with the sight glass of the oil separator from which the oil has been collected. .

  Therefore, even when oil has accumulated in the refrigerant piping or any of the refrigerator units, the oil can be efficiently collected in one oil separator, and the amount of oil can be confirmed, so that the appropriate amount can be determined. Becomes easy.

  In the invention of claim 2, in the above invention, since the control device has a test operation mode in which the valve device is closed and the compressor of each refrigerator unit is operated at the maximum capacity, before the inter-unit oil recovery mode is executed. By executing the trial operation mode, the oil accumulated in the refrigerant pipe or any of the refrigerator units can be quickly collected in the oil separator, and the amount of oil can be confirmed, so that the appropriate amount can be easily determined.

  According to the invention of claim 3, in addition to each of the above-mentioned inventions, the control device operates the compressor of each refrigerator unit with the maximum capacity in the inter-unit oil recovery mode, thereby efficiently performing the refrigerant piping or the like. It is possible to collect the oil collected in the oil separator.

  According to the invention of claim 4, in each of the above inventions, when the oil level cannot be confirmed in the sight glass of all the refrigerator units, the control device sets any refrigerator unit to the inter-unit oil recovery mode, and then If the oil level can be confirmed on the sight glass of the refrigerator unit, the inter-unit oil recovery mode is terminated, and if the oil level cannot be confirmed, the oil is added to the refrigerator unit so that the refrigerant pipe or any of the refrigerator units Even if oil accumulates in the oil and the oil level cannot be confirmed by the sight glass of any oil separator, the oil can be efficiently collected in one oil separator by performing the inter-unit oil recovery mode. The oil amount can be confirmed, and the appropriate amount can be easily determined.

  If the oil level cannot be confirmed with the collected oil separator sight glass, it is determined that the amount of oil in the refrigeration system is insufficient, and the oil is smoothly added to the refrigerator unit. Optimization can be realized. Thereby, the smooth driving | operation of the compressor of each refrigerator unit is realizable.

  According to the invention of claim 5, in the above invention, a test operation mode is executed in which the valve device is closed by the control device before the inter-unit oil recovery mode is executed, and the compressor of each refrigerator unit is operated at the maximum capacity. By checking the oil level with the sight glass of all the refrigerator units, the oil collected in the refrigerant pipe or any of the refrigerator units can be quickly obtained by executing the test operation mode before executing the inter-unit oil recovery mode. Is collected in the oil separator, and the oil amount can be confirmed at that time, and the appropriate amount can be easily determined.

  If the oil level cannot be confirmed in the oil separator of any of the refrigerator units even after execution of the trial operation mode, the oil is further collected in any of the oil separators to determine whether or not the amount is appropriate. By executing the inter-unit oil recovery mode, the oil amount can be more reliably determined. As a result, the oil amount can be reliably managed.

It is a refrigerant circuit figure of the refrigerating device of the example to which the present invention is applied. It is a refrigerant circuit diagram of each refrigerator unit. It is a schematic block diagram of an oil separator. It is an electrical block diagram of a control apparatus. It is a flowchart of the oil amount management method.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus 1 according to an embodiment to which the present invention is applied, and FIG. 2 is a refrigerant circuit diagram of each of the refrigerator units 10 and 20 constituting the refrigeration apparatus 1. The refrigeration apparatus 1 according to the embodiment realizes cooling of a plurality of showcases (use side devices, such as a refrigerator case and a refrigerator case) as a cooling storage facility installed in a store such as a supermarket. It is.

  In the refrigeration apparatus 1, a refrigerant circuit 2 is composed of a plurality of refrigerator units, in this embodiment, as an example, refrigerator units 10 and 20, and refrigerant pipes 3 that pipe-connect each showcase installed in a store. Is done. The refrigerator units 10 and 20 are configured by connecting pipes in parallel to the respective showcases (use side devices).

  The refrigerator units 10 and 20 are equipped with compressors 11 and 21, respectively. In this embodiment, the compressor 11 constituting the refrigerator unit 10 is constituted by a variable capacity compressor such as inverter control. However, the present invention is not limited to this. For example, an inverter-controlled compressor and a constant speed compressor may be connected in parallel.

  The oil separator 12 (oil separator 22 in the case of the refrigerator unit 20) is connected to the discharge side pipe 16 (the discharge side pipe 26 in the case of the refrigerator unit 20) of the compressor 11. The oil separator 12 separates and captures the oil contained in the high-pressure discharged refrigerant discharged from the compressor 11 of the refrigerator unit 10 from the refrigerant. The oil separator 12 has an oil outlet 12A (the refrigerator unit 20). In this case, an oil return circuit 13 (oil return circuit 23 in the case of the refrigerator unit 20) for returning the captured oil to the compressor 11 is connected to the oil outlet 22A).

  The oil separator 12 has a discharge gas refrigerant outlet 12B (a discharge gas refrigerant outlet 22B in the case of the refrigerator unit 20) via a refrigerant pipe 14 (a refrigerant pipe 24 in the case of the refrigerator unit 20). In the case of the machine unit 20, a condenser 25) is connected. Further, on the downstream side of the condenser 15, a high-pressure side pipe 3 </ b> A that joins with the downstream side of the condenser 25 of the other refrigerator unit 20 and is connected to a use side device such as a showcase is connected.

  The use side equipment such as a showcase to which the high-pressure side pipe 3A is connected is provided with a plurality of evaporators 30. Each evaporator 30 is connected in parallel, and a liquid electromagnetic valve 31 and an expansion valve 32 as a pressure reducing device are sequentially connected to the refrigerant inflow side of each evaporator 30. And after the refrigerant | coolant outflow side of each evaporator 30 joins in the downstream, the low voltage | pressure side piping 3B connected to each refrigerator unit 10 and 20 is connected. The low-pressure side pipe 3 </ b> B diverts corresponding to the refrigerator units 10 and 20, and is connected to the suction side of the compressors 11 and 21 via the suction-side pipes 19 and 29, respectively.

  With this configuration, when the compressors 11 and 21 of the refrigerator units 10 and 20 are operated, the high-temperature and high-pressure gas refrigerant discharged from the discharge side of the compressors 11 and 21 is the oil separators 12 and 22 and the refrigerant pipe 14. , 24 flows into the condensers 15 and 25 and dissipates heat there. The condensed and liquefied refrigerant flows into the high-pressure side pipe 3A, merges with the refrigerant that flows out from the other refrigerator unit, and corresponds to each through the liquid solenoid valves 31 on the use side equipment side such as a showcase. To the expansion valve 32, where the pressure is reduced. The refrigerant decompressed by the expansion valve 32 flows into each evaporator 30 installed in the duct of the showcase and evaporates, taking heat from the surroundings and exerting a cooling action.

  And the inside of a showcase is cooled to predetermined | prescribed temperature by circulating the cold air heat-exchanged with the evaporator 30 in the store | warehouse | chamber by the air blower which is not shown in figure. The refrigerant discharged from the evaporator 30 returns to the compressors 11 and 21 of the refrigerator units 10 and 20 through the low-pressure side pipe 3B and the suction side pipes 19 and 29.

  Each liquid electromagnetic valve 31 is opened and closed based on the temperature inside the showcase, and controls the supply of refrigerant to each evaporator 30. Thereby, when all the liquid solenoid valves 31 of the plurality of showcases connected to the refrigeration apparatus 1 are closed, the operation of the compressors 11 and 21 of the respective refrigerator units 10 and 20 is stopped, and any one of the liquid solenoid valves is stopped. It is controlled to be activated when is opened.

  Next, the oil separator 12 (or 22) in the present embodiment will be described in detail. FIG. 3 shows a schematic diagram of the oil separator 12. Here, the oil separator 12 will be described as an example. The oil separator 12 is constituted by a container having a predetermined capacity, and the gas refrigerant discharged by the compressor 11 flows from a discharge side pipe 16 connected to the upper part.

  An oil return circuit 13 is connected to the lower part of the oil separator 12 through an oil outlet 12A separated from the refrigerant inside. The oil separator 12 is connected to a refrigerant pipe 14 via a refrigerant outlet 12B separated from the oil inside. The upper end 14 </ b> A of the refrigerant pipe 14 opens at a predetermined height in the oil separator 12.

  On the side surface of the oil separator 12, a sight glass (sight glass for proper oil level confirmation) 17 for confirming the oil level in the oil separator 12 from the outside is provided. The sight glass 17 is necessary when the amount of oil sealed in the refrigeration apparatus 1 is an appropriate amount of oil in a state where the oil is collected in the oil separator 12 by a trial operation mode to be described later. It is assumed that the oil level is provided at a position where the oil level can be confirmed.

  Further, in this embodiment, an upper sight glass 18 is provided on the side surface of the oil separator 12 so as to be located above the sight glass 17 and for checking an excessive oil level. The upper sight glass 18 is provided at a position higher than the upper end 14A of the refrigerant pipe 14, or a position where the oil level at a height position substantially equal to the upper end 14A can be confirmed.

  Furthermore, in this embodiment, the oil return circuit 13 that returns oil from the oil separator 12 to the compressor 11 includes an inter-unit oil recovery pipe 40 that connects the suction side pipe 29 of the compressor 21 of the other refrigerator unit 20. Is provided. Thereby, the oil outlet 12A of the oil separator 12 of one refrigerator unit 10 and the suction side of the compressor 21 of the other refrigerator unit 20 are communicated by the inter-unit oil recovery pipe 40.

  The inter-unit oil recovery pipe 40 includes a valve device (electromagnetic opening / closing valve) 41 located on one refrigerator unit 10 side and a valve device (electromagnetic opening / closing valve) 52 located on the other refrigerator unit 20 side. It is installed.

  Similarly, an oil return circuit 23 that returns oil from the oil separator 22 of the other refrigerator unit 20 to the compressor 21 is for oil recovery between units that connects the suction side pipe 19 of the compressor 11 of the one refrigerator unit 10. A pipe 50 is provided. Accordingly, the oil outlet 22A of the oil separator 22 of the other refrigerator unit 20 and the suction side of the compressor 11 of the one refrigerator unit 10 are communicated with each other by the inter-unit oil recovery pipe 50.

  The inter-unit oil recovery pipe 50 includes a valve device (electromagnetic on-off valve) 51 located on the other refrigerator unit 20 side and a valve device (electromagnetic on-off valve) 42 located on the one refrigerator unit 10 side. It is installed.

  The oil return circuits 13 and 23 of the refrigerator units 10 and 20 are respectively provided with an oil inlet 34 and an oil outlet 35 that are manually opened and closed.

  FIG. 4 shows an electrical block diagram of the control device C of the refrigeration apparatus 1 in this embodiment. The control device C in the present embodiment is constituted by a general-purpose microcomputer, and on its input side, various sensors 36, operation switches 44 and 54 of each refrigerator unit 10, 20 and various settings and operation modes. A control panel 38 for switching is connected. On the output side, the compressors 11 and 21 of the refrigerator units 10 and 20, the valve devices 41, 42, 51 and 52 as described above, the other liquid electromagnetic valve 31... And the expansion valve 32. Etc. are connected.

  With the above configuration, the oil amount management method of the refrigeration apparatus 1 according to the present invention will be described with reference to the flowchart of FIG. First, in step S1, the operator confirms the sight glass 17 for confirming the appropriate oil level of the oil separators 12 and 22 of all the refrigerator units 10 and 20, and the oil level is detected by any of the oil separators 12 and 22. It is determined whether or not can be confirmed.

  Here, when the oil level can be confirmed by any one of the oil separators 12 and 22, the oil amount of the entire refrigeration apparatus 1, that is, each of the refrigerator units 10 and 20, has an appropriate amount.

  At this time, when the oil level can be confirmed by the upper sight glass 18 of any of the oil separators 12 and 22, the amount of oil in the entire refrigeration apparatus 1, that is, each of the refrigerator units 10 and 20, is excessive. Therefore, excess oil is extracted from the oil drain port 35 of the oil return circuit connected to the oil separator whose excess oil level is confirmed by the upper sight glass 18. At this time, the oil amount can be adjusted to an appropriate amount by extracting the oil while checking the excessive oil level with the upper sight glass 18.

  If the required oil level cannot be confirmed from the sight glass 17 of any of the oil separators 12 and 22 in step S1, the process proceeds to step S2, and the operator turns on the operation switches 44 and 54 of all the refrigerator units 10 and 20. The process proceeds to step S3, and the control panel 38 is operated to set the trial operation mode of each of the refrigerator units 10 and 20.

  As a result, the control device C closes the valve devices 41, 42, 51, 52 and operates the compressors 11, 21 with the maximum capacity in the trial operation mode. In this trial operation mode, the compressors 11 and 21 of the refrigerator units 10 and 20 are operated at the maximum capacity, so that they are accumulated in the refrigerant pipes and the like by the high-temperature gas refrigerant from the discharge side pipes 16 and 26 of the compressors 11 and 21. The collected oil is quickly recovered, and the oil is separated from the refrigerant in the oil separators 12 and 22. Then, the oil is returned to the compressors 11 and 21 via the oil return circuits 13 and 23.

  Thereafter, the operator proceeds to step S4, determines whether or not a sufficient time has elapsed for recovering the oil stored in the refrigerant circuit for a predetermined time after executing the test operation mode, and the predetermined time has elapsed. If this occurs (after waiting for a predetermined time), the process proceeds to step S5, and the oil level in the oil separators 12 and 22 from the sight glasses 17 and 17 for checking the appropriate oil level of the oil separators 12 and 22 of the refrigerator units 10 and 20 Check if there is any.

  If the required oil level can be confirmed in any one of the sight glasses 17, since the amount of oil in the entire refrigeration apparatus 1, that is, each of the refrigerator units 10 and 20, has an appropriate amount, the process proceeds to step S6. The person operates the control panel 38 to end the test operation mode.

  On the other hand, when the oil level cannot be confirmed in the sight glasses 17 and 17 of all the refrigerator units 10 and 20 in step S5, the operator proceeds to step S7 and operates the control panel 38 to select one of them. The refrigerator unit 10 or 20 is set to the inter-unit oil recovery mode.

  When the inter-unit oil recovery mode of one refrigerator unit 10 is set, the control device C closes the valve devices 41 and 52, opens the valve devices 42 and 51, and sets the compressors of the refrigerator units 10 and 20. Drive 11 and 21 with maximum capacity. In this inter-unit oil recovery mode, the compressors 11 and 21 of the refrigerator units 10 and 20 are operated at the maximum capacity, so that the refrigerant pipes 16 and 26 of the compressors 11 and 21 are discharged from the discharge pipes 16 and 26 by the high-temperature gas refrigerant. The oil collected in the oil is quickly collected, and the oil is separated from the refrigerant in the oil separators 12 and 22. Then, the oil is returned to the compressors 11 and 21 via the oil return circuits 13 and 23.

  Further, since the valve devices 51 and 42 of the inter-unit oil recovery pipe 50 connected to the oil return circuit 23 of the other refrigerator unit 20 are opened, excess oil in the refrigerator unit 20 Then, the air is sucked into the suction side of the compressor 11 of one refrigerator unit 10 through the inter-unit oil recovery pipe 50.

  As a result, the oil of the refrigeration apparatus 1 is recovered in the oil separator 12 of one of the refrigerator units 10.

  Thereafter, the operator proceeds to step S8 to determine whether or not a sufficient time has elapsed for recovering the oil stored in the refrigerant circuit for a predetermined time after the execution of the inter-unit oil recovery mode. When the time has elapsed (after waiting for a predetermined time), the process proceeds to step S9, and the refrigeration unit executing the inter-unit oil recovery mode, in this case, for checking the appropriate oil level of the oil separator 12 of the refrigeration unit 10 The presence or absence of an oil level in the oil separator 12 is confirmed from the sight glass 17.

  If the required oil level can be confirmed on the sight glass 17 of the oil separator 12, the entire refrigeration apparatus 1, that is, the amount of oil in each of the refrigerator units 10 and 20, has an appropriate amount, so the process proceeds to step S6. The operator operates the control panel 38 to end the inter-unit oil recovery mode.

  On the other hand, if the oil level cannot be confirmed with the sight glass 17 of the refrigerator unit 10 in step S9, the operator proceeds to step S10 and the oil return circuit 13 connected to the oil separator 12 of the refrigerator unit 10 concerned. Oil is added from the oil filling port 34. Then, when the oil level can be confirmed with the sight glass 17 of the oil separator 12, the addition of oil is stopped (step S9), and then the process proceeds to step S6, the control panel 38 is operated, and the refrigerator unit 10 is operated. End unit oil recovery mode. At this time, the control device C closes the opened valve devices 42 and 51.

  Here, in order to set one refrigerator unit 10 to the inter-unit oil recovery mode, the valve devices 41 and 52 are closed, the valve devices 42 and 51 are opened, and the compressors 11 and 21 are operated. Oil is recovered in the oil separator 12 of the refrigerator unit 10, but when the other refrigerator unit 20 is set to the inter-unit oil recovery mode, the valve devices 41 and 52 are opened, and the valve devices 42 and 51 are connected. The compressors 11 and 21 are closed and the oil is recovered in the oil separator 22 of the refrigerator unit 20.

  As described above, in this embodiment, by executing the inter-unit oil recovery mode, the oil is recovered to the oil separator of any of the refrigerator units via the inter-unit oil recovery pipe with the valve device opened. be able to. Therefore, it is easy to determine whether the amount of oil in the entire refrigeration apparatus 1 is an appropriate amount by checking the oil level in the oil separator with the sight glass 17 of the oil separator 12 or 22 from which the oil has been collected. Is possible.

  As a result, even when oil has accumulated in the refrigerant pipe or any of the refrigerator units, the oil can be efficiently collected in one oil separator, and the amount of oil can be confirmed. Discrimination becomes easy.

  In particular, in the inter-unit oil recovery mode, since the compressors 11 and 21 of the refrigerator units 10 and 20 are operated with the maximum capacity, it is possible to efficiently recover the oil accumulated in the refrigerant pipe or the like in the oil separator. .

  If the oil level cannot be confirmed with the collected oil separator sight glass, it is determined that the amount of oil in the refrigeration system is insufficient, and the oil is smoothly added to the refrigerator unit. Optimization can be realized. Thereby, the smooth driving | operation of the compressor of each refrigerator unit is realizable.

  In this embodiment, before the execution of the inter-unit oil recovery mode, all the valve devices 41, 42, 51, 52 provided in the inter-unit oil recovery pipes 40, 50 are closed, and each refrigerator unit is closed. By performing a test operation mode in which the compressors 11 and 21 of the 10 and 20 are operated at the maximum capacity, the oil collected in the refrigerant pipe or any of the refrigerator units is quickly collected in the oil separator. The amount of oil can be confirmed, making it easy to determine the appropriate amount.

  If the oil level cannot be confirmed in the oil separator of any of the refrigerator units even after execution of the trial operation mode, the oil is further collected in any of the oil separators to determine whether or not the amount is appropriate. By executing the inter-unit oil recovery mode, the oil amount can be more reliably determined. As a result, the oil amount can be reliably managed.

  Therefore, even when a refrigerant leak failure occurs, the oil amount in the entire refrigeration apparatus 1 can be easily optimized by executing the test operation mode and the inter-unit oil recovery mode as described above during maintenance work. It can be performed. In addition, after installation, even when there is a change in the number of installed devices on the user side or a change in the length of the refrigerant pipe, the oil amount can be easily achieved by executing the test run mode and the inter-unit oil recovery mode in this way. It is possible to check the amount and maintain an appropriate amount.

  As described above, in this embodiment, the refrigeration apparatus provided with two refrigerator units is described as an example. However, the present invention is not limited to this, and three, four, etc. The present invention can also be applied to a refrigeration apparatus provided with more than one refrigerator unit, and the same effect can be achieved.

DESCRIPTION OF SYMBOLS 1 Refrigeration apparatus 2 Refrigerant circuit 3 Refrigerant piping 10, 20 Refrigerator unit 11, 21 Compressor 12, 22 Oil separator 12A, 22A Oil outlet 12B, 22B Discharge gas refrigerant outlet 13, 23 Oil return circuit 14, 24 Refrigerant piping 15, 25 Condenser 16, 26 Discharge side piping 17 Sight glass (sight glass for checking proper oil level)
18 Upper sight glass 19, 29 Suction side piping 30 Evaporator 32 Expansion valve 34 Oil filling port 35 Oil drain port 38 Control panel 40, 50 Unit oil recovery piping 41, 42, 51, 52 Valve device 44, 54 Operation switch

Claims (5)

In a refrigeration system comprising at least two refrigerator units each equipped with a compressor connected in parallel to a user side device,
An oil separator provided in each of the refrigerator units, for separating the oil discharged from the compressor of the refrigerator unit and returning it to the compressor;
Provided in each oil separator, sight glass for checking the oil level in the oil separator,
An inter-unit oil recovery pipe communicating the oil outlet of the oil separator of one of the refrigerator units and the suction side of the compressor of the other refrigerator unit;
A valve device for controlling the flow of oil in the oil recovery pipe between the units;
A control device for controlling the valve device,
The control device has an inter-unit oil recovery mode in which the valve device of any one of the refrigerator units is opened based on a predetermined command and the compressor of each refrigerator unit is operated. .   The refrigerating apparatus according to claim 1, wherein the control device has a trial operation mode in which the valve device is closed and the compressor of each refrigerating machine unit is operated at a maximum capacity.   The refrigeration apparatus according to claim 1 or 2, wherein the control device operates a compressor of each refrigeration unit at maximum capacity in the inter-unit oil recovery mode.   When the oil level cannot be confirmed on the sight glass of all the refrigerator units, the control device sets one of the refrigerator units to the inter-unit oil recovery mode, and then the oil level is detected on the sight glass of the refrigerator unit. The refrigeration apparatus according to any one of claims 1 to 3, wherein if it can be confirmed, the inter-unit oil recovery mode is ended, and if it cannot be confirmed, oil is added to the refrigerator unit. Oil quantity management method.   Before the execution of the inter-unit oil recovery mode, the control device closes the valve device to execute the test operation mode in which the compressors of the respective refrigerator units are operated at the maximum capacity, and the sight glass of all the refrigerator units 5. The oil amount management method for a refrigeration apparatus according to claim 4, wherein the oil level is confirmed by the operation.

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