EP3913299A1 - Appareil de cycle de réfrigération - Google Patents

Appareil de cycle de réfrigération Download PDF

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Publication number
EP3913299A1
EP3913299A1 EP21185466.6A EP21185466A EP3913299A1 EP 3913299 A1 EP3913299 A1 EP 3913299A1 EP 21185466 A EP21185466 A EP 21185466A EP 3913299 A1 EP3913299 A1 EP 3913299A1
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EP
European Patent Office
Prior art keywords
oil
compressor
pipe
refrigerant
valve
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP21185466.6A
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German (de)
English (en)
Inventor
Masahiro Ito
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Electric Corp
Original Assignee
Mitsubishi Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Electric Corp filed Critical Mitsubishi Electric Corp
Priority to EP21185466.6A priority Critical patent/EP3913299A1/fr
Publication of EP3913299A1 publication Critical patent/EP3913299A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B31/00—Compressor arrangements
    • F25B31/002—Lubrication
    • F25B31/004—Lubrication oil recirculating arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B1/00—Compression machines, plants or systems with non-reversible cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B31/00—Compressor arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
    • F25B2400/06—Several compression cycles arranged in parallel
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
    • F25B2400/07—Details of compressors or related parts
    • F25B2400/075—Details of compressors or related parts with parallel compressors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2500/00—Problems to be solved
    • F25B2500/16—Lubrication
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/03—Oil level

Definitions

  • the present invention relates to a refrigeration cycle apparatus, and more particularly to a refrigeration cycle apparatus including a compressor group in which a plurality of compressors are connected in parallel.
  • a refrigeration cycle apparatus is provided with a refrigerant circuit in which refrigerant is circulated by a plurality of compressors.
  • the amount of oil in one compressor and the amount of oil in another compressor may become unequal. For example, when the amount of oil is insufficient in one compressor, the compressor may suffer from galling.
  • PTL 1 discloses such a refrigeration cycle apparatus.
  • a refrigeration cycle apparatus when a refrigerator is in a transient operation, for example, when the refrigerator is started or restarted after defrosting, the refrigerant may not be sufficiently gasified, and thereby, the refrigerant containing liquid state refrigerant (liquid refrigerant) may be sucked into the compressor. This phenomenon is called a liquid back.
  • the liquid refrigerant is fed into the one compressor together with oil, the actual amount of oil in the compressor is reduced, which lowers the concentration of the oil.
  • the oil level of the one compressor is substantially the same as the oil level of the other compressors, despite that the one compressor has a lower oil concentration, and no oil will be supplied from the other compressors, the one compressor may suffer from galling.
  • the present invention has been made to solve the above problem, and an object thereof is to provide a refrigeration cycle apparatus capable of preventing a compressor from suffering from galling even when a liquid back occurs.
  • the refrigeration cycle apparatus is provided with a refrigerant circuit which is formed by connecting a compressor group in which a plurality of compressors including a first compressor and a second compressor are connected in parallel, a four-way valve, a condenser, an expansion valve, an evaporator, and an accumulator via a refrigerant pipe, and further includes an oil storage.
  • the oil storage is connected to the discharge side of the compressor group via a first on-off valve, connected to the accumulator via a second on-off valve, and connected to the suction side of the compressor group via a third on-off valve.
  • the refrigeration cycle apparatus of the present invention when a liquid back occurs, the oil stored in the oil storage is fed to the compressor group, which makes it possible to prevent the compressor group from suffering from galling.
  • the refrigeration cycle apparatus 1 includes a compressor group 3, a four-way valve 5, a first heat exchanger 7, an expansion valve 9, a second heat exchanger 11, and an accumulator 13 as the basic components.
  • the second heat exchanger 11 is a water heat exchanger.
  • the compressor group 3, the four-way valve 5, the first heat exchanger 7, the expansion valve 9, the second heat exchanger 11, and the accumulator 13 are connected in this order via a refrigerant pipe 50 to form a refrigerant circuit.
  • the compressor group 3 is connected to the four-way valve 5 via a refrigerant pipe 51 (50).
  • the four-way valve 5 is connected to the first heat exchanger 7 via a refrigerant pipe 52 (50).
  • the first heat exchanger 7 is connected to the expansion valve 9 via a refrigerant pipe 53 (50).
  • the expansion valve 9 is connected to the second heat exchanger 11 via a refrigerant pipe 54 (50).
  • the second heat exchanger 11 is connected to the four-way valve 5 via a refrigerant pipe 55 (50).
  • the four-way valve 5 is connected to the accumulator 13 via a refrigerant pipe 56 (50).
  • the accumulator 13 is connected to the compressor group 3 via a refrigerant pipe 57 (50).
  • the compressor group 3 includes a first compressor 3a and a second compressor 3b.
  • the first compressor 3a and the second compressor 3b are connected in parallel.
  • the discharge side of the first compressor 3a is connected to the refrigerant pipe 51 via a refrigerant pipe 51a.
  • the discharge side of the second compressor 3b is connected to the refrigerant pipe 51 via a refrigerant pipe 51b.
  • the suction side of the first compressor 3a is connected to the refrigerant pipe 57 via a refrigerant pipe 57a.
  • the suction side of the second compressor 3b is connected to the refrigerant pipe 57 via a refrigerant pipe 57b.
  • the refrigeration cycle apparatus 1 further includes an oil storage 15 configured to supply oil stored therein to the compressor group 3 (the first compressor 3a and the second compressor 3b).
  • the oil storage 15 is connected to the discharge side of the compressor group 3 via a discharge gas bypass pipe (first pipe) 17.
  • One end of the discharge gas bypass pipe 17 is connected to the refrigerant pipe 51 as if it is branched from the refrigerant pipe 51.
  • the other end of the discharge gas bypass pipe 17 is connected to an upper end of the oil storage 15.
  • the discharge gas bypass pipe 17 is provided with a first solenoid valve (first on-off valve) 19.
  • the oil storage 15 is connected to the accumulator 13 via a first oil bypass pipe (second pipe) 21.
  • One end of the first oil bypass pipe 21 is connected to a side portion of the accumulator 13 close to the bottom face thereof.
  • the other end of the first oil bypass pipe 21 is connected to the upper end of the oil storage 15.
  • the first oil bypass pipe 21 is provided with a second solenoid valve (second on-off valve) 23.
  • the oil storage 15 is connected to the compressor group 3 (the first compressor 3a and the second compressor 3b) via a second oil bypass pipe (third pipe) 25.
  • the second oil bypass pipe 25 includes a main pipe 25a, and a first branch pipe 25b and a second branch pipe 25c which are branched from the main pipe 25a.
  • the oil storage 15 is connected to the first compressor 3a via the main pipe 25a and the first branch pipe 25b.
  • the first branch pipe 25b is connected to a lower end of the first compressor 3a.
  • the oil storage 15 is connected to the second compressor 3b via the main pipe 25a and the second branch pipe 25c.
  • the second branch pipe 25c is connected to a lower end of the second compressor 3b.
  • the main pipe 25a is provided with a third solenoid valve 27.
  • the accumulator 13 is connected to the compressor group 3 via a first oil pipe (fourth pipe) 31a and a second oil pipe (fourth pipe) 31b.
  • One end of the first oil pipe 31a and one end of the second oil pipe 31b join together as one end of a common oil pipe 31 connected to a lower end of the accumulator 13.
  • the other end of the first oil pipe 31a is connected to a lower end of the first compressor 3a.
  • the other end of the second oil pipe 31b is connected to a lower end of the second compressor 3b.
  • the oil storage 15 is arranged relative to the compressor group 3 in such a manner that the bottom of the oil stored in the oil storage 15, in other words, the bottom surface of a space for storing oil in the oil storage 15 is located at a position with a height H1 from the bottom of the oil in the compressor group 3, in other words, the bottom surface of a space for storing oil in the compressor group 3, and the oil level of the oil maximally stored in the oil storage 15 is located at a position with a height H3 from the bottom of the oil in the compressor group 3.
  • the accumulator 13 is arranged relative to the compressor group 3 in such a manner that the bottom of the oil stored in the accumulator 13, in other words, the bottom surface of a space for storing oil in the accumulator 13 is located at a position with a height H2 from the bottom of the oil in the compressor group 3, and the height H2 is higher than the oil level of the oil maximally stored in the oil storage 15.
  • the position relationship of the oil storage 15, the accumulator 13 and the compressor group 3 is configured so as to facilitate an oil equalizing operation for equalizing oil in the compressor group 3, an oil returning operation for returning oil to the compressor group 3 when a liquid back occurs, and an oil filling operation for fully filling the oil storage 13 with oil when a liquid back occurs.
  • Fig. 3 the flow of the refrigerant circulated in the refrigerant circuit is indicated by the arrows.
  • the high temperature and high pressure gas refrigerant discharged from the first compressor 3a flows through the refrigerant pipe 51a.
  • the high temperature and high pressure gas refrigerant discharged from the second compressor 3b flows through the refrigerant pipe 51b.
  • the refrigerant flowing through the refrigerant pipe 51a and the refrigerant flowing through the refrigerant pipe 51b join together and flow through the refrigerant pipe 51.
  • the refrigerant flowing through the refrigerant pipe 51 is fed to the first heat exchanger 7 which functions as a condenser via the four-way valve 5 and the refrigerant pipe 52.
  • the gas refrigerant is condensed and liquefied to a high pressure liquid refrigerant.
  • the high pressure liquid refrigerant discharged from the first heat exchanger 7 flows through the refrigerant pipe 53, and is converted by the expansion valve 9 into a two-phase refrigerant including a low pressure gas refrigerant and a liquid refrigerant.
  • the two-phase refrigerant is fed to the second heat exchanger 11 which functions as an evaporator via the refrigerant pipe 54.
  • the second heat exchanger 11 is a water heat exchanger.
  • heat is exchanged between the refrigerant and water. Due to the heat exchange, the water is cooled, and the liquid refrigerant in the two-phase refrigerant is vaporized into a low pressure gas refrigerant.
  • the low pressure gas refrigerant discharged from the second heat exchanger 11 is fed to the accumulator 13 via the refrigerant pipe 55, the four-way valve 5 and the refrigerant pipe 56.
  • the oil contained in the refrigerant is separated in the accumulator 13, and the separated oil is stored in the accumulator 13.
  • the refrigerant separated from the oil flows through the refrigerant pipe 57 and then flows through each of the refrigerant pipe 57a and the refrigerant pipe 57b which are branched from the refrigerant pipe 57.
  • the refrigerant flowing through the refrigerant pipe 57a is fed to the first compressor 3a where the refrigerant is compressed into a high temperature and high pressure gas refrigerant and discharged from the first compressor 3a thereafter.
  • the refrigerant flowing through the refrigerant pipe 57b is fed to the second compressor 3b where the refrigerant is compressed into a high temperature and high pressure gas refrigerant and discharged from the second compressor 3b thereafter. This cycle is repeated subsequently.
  • Fig. 4 the flow of the refrigerant is indicated by the arrows.
  • the high temperature and high pressure gas refrigerant discharged from the first compressor 3a flows through the refrigerant pipe 51a, and the high temperature and high pressure gas refrigerant discharged from the second compressor 3b flows through the refrigerant pipe 51b, and then join together and flow through the refrigerant pipe 51.
  • the refrigerant flowing through the refrigerant pipe 51 is fed to the second heat exchanger 11 (water heat exchanger) which functions as a condenser via the four-way valve 5 and the refrigerant pipe 55.
  • the second heat exchanger 11 water heat exchanger
  • the second heat exchanger 11 heat is exchanged between the refrigerant and water. Due to the heat exchange, the water is heated, and the high temperature and high pressure gas refrigerant is condensed and liquefied to a high pressure liquid refrigerant.
  • the high pressure liquid refrigerant discharged from the second heat exchanger 11 flows through the refrigerant pipe 54, and is converted by the expansion valve 9 into a two-phase refrigerant including a low pressure gas refrigerant and a liquid refrigerant.
  • the two-phase refrigerant is fed to the first heat exchanger 7 which functions as an evaporator via the refrigerant pipe 53.
  • the liquid refrigerant in the two-phase refrigerant is vaporized into a low pressure gas refrigerant.
  • the low pressure gas refrigerant discharged from the first heat exchanger 7 is fed to the accumulator 13 via the refrigerant pipe 52, the four-way valve 5 and the refrigerant pipe 56.
  • the refrigerant separated from the oil in the accumulator 13 is fed to the first compressor 3a via the refrigerant pipe 57 and the refrigerant pipe 57a, and meanwhile is fed to the second compressor 3b via the refrigerant pipe 57 and the refrigerant pipe 57b.
  • the refrigerant fed to each of the first compressor 3a and the second compressor 3b is compressed into a high temperature and high pressure gas refrigerant and discharged from each of the first compressor 3a and the second compressor 3b thereafter. This cycle is repeated subsequently.
  • step S1 the compressor group 3 is activated.
  • step S2 the first solenoid valve 19, the second solenoid valve 23 and the third solenoid valve 27 are closed.
  • step S3 whether or not the oil storage 15 is full of oil is determined. If it is determined in step S3 that the oil storage is full of oil, the second solenoid valve 23 and the third solenoid valve 27 are kept close in step S4.
  • step S3 if it is determined in step S3 that the oil storage is not full of oil, the second solenoid valve 23 and the third solenoid valve 27 are opened so as to supply the oil stored in the accumulator 13 to the oil storage 15 until the oil storage 15 is full of oil. After the oil storage 13 is full of oil, the second solenoid valve 23 and the third solenoid valve 27 are closed in step S4.
  • step S5 whether or not a command to stop the compressor group 3 is issued is determined. If it is determined that a command to stop the compressor group 3 is issued in step S5, the compressor group 3 is stopped in step S6. On the other hand, if it is determined that a command to stop the compressor group 3 is not issued in step S5, the procedure returns to step S3, the operations of steps S3 to S5 are repeated.
  • step LB2 if the second solenoid valve 23 is closed, then it is kept close; and if the second solenoid valve 23 is open, then the second solenoid valve 23 is closed.
  • step LB3 whether or not the concentration of the oil in the compressor group is equal to or greater than a reference value (first value) is determined. If it is determined that the concentration of the oil in the compressor group 3 is equal to or greater than the reference value (first value) in step LB3, the first solenoid valve 19 and the third solenoid valve 27 are kept close in step LB4.
  • the refrigerant containing the liquid refrigerant flows into the compressor group 3, which will lower the concentration of the oil in the compressor group 3. If it is determined that the concentration of the oil in the compressor group 3 is lower than the reference value, the first solenoid valve 19 and the third solenoid valve 27 are opened in step LB6.
  • the second solenoid valve 23 is closed (step LB2), if the first solenoid valve 19 and the third solenoid valve 27 are opened, the oil stored in the oil storage 15 is fed to the compressor group 3 via the second oil bypass pipe 25 by the discharge pressure of the compressor group 3.
  • the oil in the oil storage 15 is fed to the compressor group 3 until the concentration of the oil in the compressor group 3 becomes equal to or higher than the reference value.
  • the first solenoid valve 19 and the third solenoid valve 27 are closed in step LB4.
  • the series of operations in steps LB 1 to LB5 are repeated subsequently.
  • the refrigeration cycle apparatus 1 described above is provided with the oil storage 15 configured to store oil for the compressor group 3, and when a liquid back occurs, the oil stored in the oil storage 15 is fed to the compressor group 3 so as to prevent the compressor group 3 from suffering from galling.
  • the effect will be described in comparison with a refrigeration cycle apparatus according to a comparative example.
  • a refrigeration cycle apparatus 101 includes a compressor group 103 including a first compressor 103a and a second compressor 103b, a four-way valve 105, an outdoor heat exchanger 107, an outdoor decompressor 109a, an indoor decompressor 109b, an indoor heat exchanger 111, and an accumulator 113.
  • the compressor group 103 and the like are connected via a refrigerant pipe 150 to form a refrigerant circuit.
  • the refrigeration cycle apparatus 101 further includes an oil equalizing device 151 configured to equalize the oil in the compressor group 103.
  • the oil equalizing device 151 includes a connection pipe 141, a gas-liquid separation unit 143, an oil pipe 145, and an oil pipe 147.
  • the connection pipe 141 is connected between the compressor group 103 and the gas-liquid separation unit 143.
  • the oil pipe 145 is connected between the gas-liquid separation unit 143 and the refrigerant pipe 150 of the refrigerant circuit.
  • the oil pipe 147 is connected between the gas-liquid separation unit 143 and the accumulator 113.
  • the refrigerant discharged from the compressor group 103 passes through the four-way valve 105, the outdoor heat exchanger 107, the outdoor decompressor 109a, the indoor decompressor 109b, the indoor heat exchanger 111, the four-way valve 105, and the accumulator 113 in order and flows back to the compressor group 103. This cycle is repeated subsequently.
  • the refrigerant discharged from the compressor group 103 passes through the four-way valve 105, the indoor heat exchanger 111, the indoor decompressor 109b, the outdoor decompressor 109a, the outdoor heat exchanger 107, the four-way valve 105, and the accumulator 113 in order and flows back to the compressor group 103. This cycle is repeated subsequently.
  • the oil 171 in the first compressor 103a flows into the gas-liquid separation unit 143 via the connection pipe 141, and thereby, the gas-liquid separation unit 143 is filled with the oil 171.
  • a part of the oil 171 in the gas-liquid separation unit 143 flows back to the first compressor 103a via the oil pipe 147, and the rest of the oil 171 in the gas-liquid separation unit 143 flows into the refrigerant pipe 150 via the oil pipe 145.
  • the oil 171 flowing into the refrigerant pipe 150 is fed to the compressor group 103 together with the refrigerant.
  • the oil 171 in the first compressor 103a with excessive oil may be gradually reduced, and similarly, the oil in a compressor (not shown) with less oil may be gradually increased.
  • the oil equalizing operation for equalizing the amount of the oil 171 in the compressor group 103 is carried out in the refrigeration cycle apparatus 101 according to the comparative example.
  • the low concentration oil 73 flowing into the gas-liquid separation unit 143 is fed to the compressor group 103 including the first compressor 103a via the oil pipes 145, 147 and the like. Since the oil 73 with a low concentration is fed to the first compressor 103a, the oil 71 can not be sufficiently supplied to the first compressor 103a, whereby the first compressor 103a may suffer from galling.
  • the refrigeration cycle apparatus 1 when a liquid back occurs, the oil in the oil storage 15 is supplied to the compressor group 103. The detail thereof will be described hereinafter.
  • step S1 to step S6 the concentration of oil in the compressor group 3 is repeatedly detected (see Fig. 6 ).
  • the refrigerant containing the liquid refrigerant is fed to the accumulator 13 together with the oil. Therefore, the amount of the oil 73 with a low concentration increases in the accumulator 13.
  • the refrigerant containing the liquid refrigerant is fed to the compressor group 3 together with the oil 73, the amount of the oil 73 with a low concentration increases in the compressor group 3.
  • the first solenoid valve 19, the second solenoid valve 23 and the third solenoid valve 27 are all closed.
  • step LB3 When it is detected that the concentration of the oils 71 and 73 in the compressor group 3 is lower than the reference value (step LB3), as illustrated in Fig. 11 , the first solenoid valve 19 and the third solenoid valve 27 are opened with the second solenoid valve 23 being kept close (step LB6). As a result, the refrigerant discharged from the compressor group 3 flows through the discharge gas bypass pipe 17 which is branched from the refrigerant pipe 51 (and through the first solenoid valve 19).
  • the oil 71 stored in the oil storage 15 is fed to the compressor group 3.
  • the oil 71 is fed to the first compressor 3a via the main pipe 25a (the third solenoid valve 27) and the first branch pipe 25b of the second oil bypass pipe 25.
  • the oil 71 is fed to the second compressor 3b via the main pipe 25a and the second branch pipe 25c.
  • step LB3 concentration of the oils 71 and 73 in the compressor group 3 reaches the reference value (step LB3).
  • the first solenoid valve 19 and the third solenoid valve 27 are closed (step LB4). Thereafter, the normal operation (see Fig. 5 ) is performed while regularly detecting whether or not a liquid back occurs.
  • the oil 71 preliminarily stored in the oil storage 15 is fed to the compressor group 3 when a liquid back occurs, which makes it possible to prevent the compressor group 3 from suffering from galling.
  • a method for detecting the degree of superheat (overheat) on the discharge side or the suction side of the compressor group 3 may be given.
  • the degree of superheat refers to the difference between the temperature of superheated vapor and the temperature of saturated dry vapor.
  • a reference value for the degree of superheat may be set in advance, and if the degree of superheat becomes lower than the reference value, it is determined that the liquid back has occurred.
  • a method for detecting the surface temperature of a compressor in the compressor group 3 may be given.
  • the liquid refrigerant is fed to the compressor group 3, which may cause the temperature of the compressor to decrease. Therefore, a reference value for the surface temperature may be set in advance, and if the surface temperature becomes lower than the reference value, it is determined that the liquid back has occurred.
  • an oil sensor may be provided in the compressor group 3 to detect the concentration of oil directly. If the concentration of the detected oil is lower than a reference value set in advance for the oil concentration, it is determined that the liquid back has occurred.
  • the oil 71 stored in the oil storage 15 is fed to the compressor group 3. Thereby, the oil storage 15 is not full of the oil 71.
  • an operation for fully filling the oil storage 15 with the oil 71 will be explained.
  • an operation of feeding the oil 71 stored in the accumulator 13 to the oil storage 15 is performed.
  • the second solenoid valve 23 and the third solenoid valve 27 are opened with the first solenoid valve 19 being kept close.
  • the oil 71 in the accumulator 13 is fed to the oil storage 15 via the first oil bypass pipe 21 (and the first solenoid valve 23).
  • the second solenoid valve 23 and the third solenoid valve 27 are closed. In this way, the operation for fully filling the oil storage 15 with the oil 71 is completed in preparation for a liquid back.
  • an oil level sensor may be disposed in the oil storage 15. By detecting the oil level of the oil fed from the accumulator 13 to the oil storage 15 with the oil level sensor, it is possible to determine that the oil storage is full of oil.
  • the second solenoid valve 23 and the third solenoid valve 27 may be opened for a preset duration.
  • the pressure loss from the accumulator 13 to the oil storage 15 may be estimated based on the position relationship between the accumulator 13 and the oil storage 15 and the structural configurations such as the length and the inner diameter of the first oil bypass pipe 21 and the like. Based on the pressure loss, the duration required to fully fill the oil storage 15 with oil may be calculated. By setting the duration in advance, it is possible to fully fill the oil storage 15 with oil.
  • the compressor group 3 of the refrigeration cycle apparatus 1 includes a first compressor 3a and a second compressor 3b.
  • An induction motor for each of the first compressor 3a and the second compressor 3b is driven at a desired frequency (rotational speed) according to the operation environment.
  • the refrigerant discharged from the compressor group 3 flows through the refrigerant pipe 50 together with the oil.
  • the frequency should be changed accordingly. For example, as illustrated in Fig. 14 , when the frequency suddenly drops, the amount of the oil 71 in the second compressor 3b may become less than the amount of the oil 71 in the first compressor 3a. In addition, even when there is no change in the frequency, due to the arrangement and connection of the refrigerant pipes 50 in the refrigerant circuit, the amount of the oil 71 in the first compressor 3a and the amount of the oil 71 in the second compressor 3b may become unequal.
  • the equalizing operation is performed so as to make the amount of the oil 71 in the first compressor 3a and the amount of the oil 71 in the second compressor 3b substantially equal to each other based on the difference in the oil level of the oil 71.
  • the oil 71 in the accumulator 13 is fed to the second compressor 3b via the oil pipe 31 and the second oil pipe 31b (indicated by the arrows).
  • the oil 71 in the first compressor 3a is fed to the second compressor 3b via the first oil pipe 31a and the second oil pipe 31b (indicated by the arrows).
  • the amount of the oil 71 in the first compressor 3a and the amount of the oil 71 in the second compressor 3b are made substantially equal.
  • the equalizing operation may be performed regularly during the operation of the refrigeration cycle apparatus 1.
  • the oil equalizing operation is performed so as to make the amount of the oil 71 in the first compressor 3a and the amount of the oil 71 in the second compressor 3b of the compressor group 3 equal to each other.
  • the oil 71 stored in the oil storage 15 is fed to the first compressor 3a or the second compressor 3b containing the oil 73 with a low concentration, which makes it possible to prevent the first compressor 3a or the second compressor 3b from suffering from galling.
  • the oil 71 is fed from the accumulator 13 to the oil storage 15 so as to fully fill the oil storage 15 with the oil 71 in preparation for another liquid back.
  • a third solenoid valve 27a is provided in the first branch pipe 25b of the second oil bypass pipe 25, and a third solenoid valve 27b is provided in the second branch pipe 25c of the second oil bypass pipe 25.
  • the other configurations are the same as those of the refrigeration cycle apparatus 1 illustrated in Fig. 1 .
  • the third solenoid valve 27a is provided for the first compressor 3a and the third solenoid valve 27b is provided for the second compressor 3b, so that it is possible to selectively feed the oil 71 stored in the oil storage 15 to the first compressor 3a and/or the second compressor 3b containing the oil 71, 73 with a low concentration.
  • a compressor group in which two compressors, that is, a first compressor 3a and a second compressor 3b are connected in parallel is given as an example of the compressor group 3.
  • the number of compressors in the compressor group 3 is not limited to two, it may be three or more.
  • refrigeration cycle apparatus described in the embodiment may be configured in various combination where necessary.
  • the present invention is effectively used in a refrigeration cycle apparatus including a compressor group in which a plurality of compressors are connected in parallel.
  • 1 refrigeration cycle apparatus; 3: compressor group; 3a: first compressor; 3b: second compressor; 5: four-way valve; 7: condenser (first heat exchanger); 9: expansion valve; 11: evaporator (second heat exchanger); 13: accumulator; 15: oil storage; 17: discharge gas bypass pipe; 19: first solenoid valve; 21: first oil bypass pipe; 23: second solenoid valve; 25: second oil bypass pipe; 25a: main pipe; 25b: first branch pipe; 25c: second branch pipe; 27, 27a, 27b: third solenoid valve; 31: oil pipe; 31a: first oil pipe; 31b: second oil pipe; 50, 51, 51a, 51b, 52, 53, 54, 55, 56, 57, 57a, 57b: refrigerant pipe; 71, 73: oil

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Compressor (AREA)
  • Compression-Type Refrigeration Machines With Reversible Cycles (AREA)
EP21185466.6A 2016-12-21 2016-12-21 Appareil de cycle de réfrigération Withdrawn EP3913299A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP21185466.6A EP3913299A1 (fr) 2016-12-21 2016-12-21 Appareil de cycle de réfrigération

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
PCT/JP2016/088114 WO2018116407A1 (fr) 2016-12-21 2016-12-21 Dispositif à cycle de réfrigération
EP16924560.2A EP3561410A4 (fr) 2016-12-21 2016-12-21 Dispositif à cycle de réfrigération
EP21185466.6A EP3913299A1 (fr) 2016-12-21 2016-12-21 Appareil de cycle de réfrigération

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EP3913299A1 true EP3913299A1 (fr) 2021-11-24

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EP21185466.6A Withdrawn EP3913299A1 (fr) 2016-12-21 2016-12-21 Appareil de cycle de réfrigération
EP16924560.2A Pending EP3561410A4 (fr) 2016-12-21 2016-12-21 Dispositif à cycle de réfrigération

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US (1) US20190301778A1 (fr)
EP (2) EP3913299A1 (fr)
JP (1) JP6745909B2 (fr)
CN (1) CN110088540B (fr)
WO (1) WO2018116407A1 (fr)

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US11460224B2 (en) * 2018-10-31 2022-10-04 Emerson Climate Technologies, Inc. Oil control for climate-control system
CN118140103A (zh) * 2021-11-01 2024-06-04 三菱电机株式会社 制冷循环装置
WO2024077250A1 (fr) * 2022-10-07 2024-04-11 Johnson Controls Tyco IP Holdings LLP Système de réfrigération ayant une charge de poussée de compresseur réduite

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Also Published As

Publication number Publication date
WO2018116407A1 (fr) 2018-06-28
JP6745909B2 (ja) 2020-08-26
JPWO2018116407A1 (ja) 2019-10-24
CN110088540A (zh) 2019-08-02
US20190301778A1 (en) 2019-10-03
EP3561410A1 (fr) 2019-10-30
CN110088540B (zh) 2021-08-17
EP3561410A4 (fr) 2020-02-12

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