WO2022224304A1 - 熱源ユニット - Google Patents

熱源ユニット Download PDF

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Publication number
WO2022224304A1
WO2022224304A1 PCT/JP2021/015864 JP2021015864W WO2022224304A1 WO 2022224304 A1 WO2022224304 A1 WO 2022224304A1 JP 2021015864 W JP2021015864 W JP 2021015864W WO 2022224304 A1 WO2022224304 A1 WO 2022224304A1
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WO
WIPO (PCT)
Prior art keywords
oil
flow path
compressor
oil return
refrigerant
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.)
Ceased
Application number
PCT/JP2021/015864
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English (en)
French (fr)
Japanese (ja)
Inventor
俊介 菊地
達也 ▲雑▼賀
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Mitsubishi Electric Corp
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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 PCT/JP2021/015864 priority Critical patent/WO2022224304A1/ja
Priority to JP2023515890A priority patent/JP7412639B2/ja
Publication of WO2022224304A1 publication Critical patent/WO2022224304A1/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • 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

Definitions

  • the present disclosure relates to heat source units.
  • the heat source unit sends out the refrigerant compressed by the compressor to the refrigerant circuit.
  • Refrigerating machine oil is injected into the compressor for smooth driving of mechanical parts such as a motor and a shaft.
  • a part of the refrigerating machine oil in the compressor is discharged from the compressor together with the refrigerant.
  • refrigerant is mixed with refrigerating machine oil and discharged from the oil outlet of the oil separator. Therefore, when the refrigerating machine oil is returned from the oil outlet of the oil separator to the suction port of the compressor, part of the high-pressure refrigerant discharged from the compressor toward the load unit flows into the load unit. back to the low pressure side of As a result, the refrigerating capacity of the heat source unit is lowered. By returning the refrigerating machine oil from the oil separator to the compressor through the intermediate pressure port, it is possible to prevent such a decrease in refrigerating capacity.
  • the present disclosure is intended to solve such problems, and aims to solve the shortage of refrigerating machine oil in the compressor while preventing the performance of the heat source unit from deteriorating as much as possible.
  • the present disclosure relates to a heat source unit of a refrigeration system configured to be connected to a load unit including an expansion valve and a first heat exchanger.
  • the heat source unit is arranged in the first flow path forming a circulation flow path in which the refrigerant circulates by being connected to the load unit, and sucks the refrigerant from the suction port and the intermediate pressure port and discharges the refrigerant.
  • a compressor configured to discharge refrigerant from a port; an oil separator positioned downstream of the compressor in the first flow path and having a refrigerant inlet, a refrigerant outlet and an oil outlet; and an oil separator in the first flow path.
  • the refrigerating machine oil returns from the intermediate pressure port to the compressor through the second flow path.
  • the refrigerating machine oil returns from the suction port to the compressor.
  • FIG. 1 is an overall configuration diagram of a refrigeration system according to Embodiment 1.
  • FIG. 4 is a flowchart for explaining control of a control device according to Embodiment 1;
  • FIG. 2 is an overall configuration diagram of a refrigerating apparatus according to Embodiment 2;
  • 9 is a flowchart for explaining control of a control device according to Embodiment 2;
  • FIG. 11 is an overall configuration diagram of a refrigerating apparatus according to Embodiment 3;
  • FIG. 10 is a flowchart for explaining control of a control device according to Embodiment 3;
  • FIG. FIG. 11 is an overall configuration diagram of a refrigeration system according to Embodiment 4;
  • FIG. 12 is a flowchart for explaining control of a control device according to Embodiment 4;
  • FIG. FIG. 11 is an overall configuration diagram of a refrigeration system according to Embodiment 5;
  • FIG. 11 is a flowchart for explaining control of a control device according to Embodiment 5
  • FIG. 1 is an overall configuration diagram of a refrigeration system 301 according to Embodiment 1.
  • the refrigerator 301 has a heat source unit 101 and a load unit 201 . Since the heat source unit 101 is usually arranged outdoors, it is sometimes called an outdoor unit. In this embodiment, the heat source unit 101 operates as a cold heat source that discharges heat to the outside. The heat source unit 101 is connected with the load unit 201 .
  • the heat source unit 101 includes a compressor 1, an oil separator 2, a second heat exchanger 3, a third heat exchanger 4, an injection expansion valve 5, an accumulator 8, and a controller 50.
  • the load unit 201 has an expansion valve 6 and a first heat exchanger 7 .
  • the compressor 1, the oil separator 2, the second heat exchanger 3, and the third heat exchanger 4 are connected by pipes 11-13.
  • the accumulator 8 and the compressor 1 are connected by a pipe 16 .
  • a pipe 14 connected to the third heat exchanger 4 is connected to the expansion valve 6 of the load unit 201 .
  • a pipe 15 connected to the accumulator 8 is connected to the first heat exchanger 7 of the load unit 201 .
  • the pipes 11 to 16 are connected to the load unit 201 to form a first flow path forming a circulation flow path in which the refrigerant circulates.
  • the circulation flow path is sometimes called the main circuit of the refrigeration cycle.
  • the compressor 1 includes a discharge port G1, a suction port G2, and an intermediate pressure port G3.
  • the compressor 1 includes mechanical parts such as a motor and a shaft. Refrigerant oil is injected into the compressor 1 . Refrigerant oil maintains the lubricity of mechanical parts.
  • the compressor 1 is configured to adjust the rotation speed according to a control signal from the control device 50. By adjusting the rotation speed of the compressor 1, the circulation amount of the refrigerant changes. Thereby, the refrigerating capacity of the refrigerating device 301 can be adjusted.
  • a high-temperature, high-pressure gaseous refrigerant is discharged from the discharge port G1 of the compressor 1. At this time, part of the refrigerating machine oil in the compressor 1 is discharged together with the refrigerant. The refrigerant and refrigerating machine oil discharged from the discharge port G1 go to the oil separator 2 .
  • the oil separator 2 includes a refrigerant inlet P1, a refrigerant outlet P2, and an oil outlet P3.
  • the refrigerant and refrigerating machine oil discharged from the discharge port G1 flow into the oil separator 2 from the refrigerant inlet P1.
  • the oil separator 2 separates refrigerant and refrigerating machine oil. After being discharged from the refrigerant outlet P2, the refrigerant is directed to the second heat exchanger 3 functioning as a condenser.
  • the second heat exchanger 3 is arranged downstream of the oil separator 2 .
  • the refrigerant is condensed by exchanging heat with the outside air.
  • the condensed refrigerant flows into the third heat exchanger 4 before going to the load unit 201 .
  • heat exchange is performed between the refrigerant flowing from the second heat exchanger 3 through the pipe 13 and the refrigerant flowing from the branch point a of the pipe 14 through the injection pipes 21 and 22 .
  • An injection expansion valve 5 is arranged between the injection pipe 21 and the injection pipe 22 .
  • the injection expansion valve 5 expands the refrigerant flowing in from the branch point a, and then allows the refrigerant to flow into the third heat exchanger 4 .
  • the refrigerant discharged from the second heat exchanger 3 is cooled in the third heat exchanger 4 before going to the load unit 201 through the branch point a.
  • the third heat exchanger 4 functions as a supercooler.
  • the refrigerant that has flowed into the third heat exchanger 4 from the injection pipe 22 returns to the compressor 1 through the injection pipe 23 and the intermediate pressure port G3.
  • the injection pipes 21 to 23 constitute an injection flow path (second flow path) different from the first flow path that constitutes the main circuit.
  • the injection flow path branches from the branch point a of the pipe 14 toward the load unit 201, and is configured to return the refrigerant that has passed through the second heat exchanger 3 to the compressor 1 through the intermediate pressure port G3.
  • the injection expansion valve 5 is an electronic expansion valve whose opening is changed according to a signal given from the outside.
  • the discharge temperature of the compressor 1 can be controlled by adjusting the flow rate of the refrigerant flowing through the injection passage with the injection expansion valve 5 . Therefore, it is possible to operate efficiently in a situation where the discharge temperature of the compressor 1 rises excessively.
  • the flow path of the refrigerant discharged from the third heat exchanger 4 branches at the branch point a into a flow path that goes through the pipe 14 and goes to the load unit 201 and a flow path that goes to the injection pipe 21 .
  • the refrigerant directed to the load unit 201 is expanded by the expansion valve 6 and then flows into the first heat exchanger 7 .
  • the refrigerant that has flowed into the first heat exchanger 7 evaporates by absorbing heat from the air inside the chamber, thereby cooling the room.
  • the refrigerant discharged from the first heat exchanger 7 returns to the heat source unit 101 through the pipe 15 .
  • the refrigerant that has returned to the heat source unit 101 flows into the accumulator 8 .
  • the accumulator 8 is installed on the suction port G2 side of the compressor 1 . In other words, the accumulator 8 is arranged upstream of the compressor 1 .
  • the accumulator 8 separates the gaseous and liquid refrigerants. The gaseous refrigerant separated by the accumulator 8 is sucked into the compressor 1 through the suction port G2 through the pipe 16 .
  • An oil outlet P3 of the oil separator 2 is connected to an oil return pipe 31 .
  • the oil return pipe 31 is connected to the oil return pipes 32 and 33 by a three-way valve 40 .
  • the oil return pipe 32 is connected to the injection pipe 23 .
  • the oil return pipe 33 is connected to the suction side pipe 16 of the compressor 1 .
  • the three-way valve 40 switches the flow path of the refrigerating machine oil discharged from the oil outlet P3 between the first oil return flow path and the second oil return flow path.
  • the first oil return flow path is a flow path through which the refrigerating machine oil returns to the compressor 1 from the intermediate pressure port G3 through the oil return pipes 31 and 32 and the injection pipe 23 .
  • the second oil return flow path is a flow path through which the refrigerating machine oil returns to the compressor 1 from the suction port G2 through the oil return pipes 31, 33 and the pipe 16.
  • a mechanism combining two valves may be used to switch the oil return channel between the first oil return channel and the second oil return channel.
  • the refrigerating machine oil discharged from the oil outlet P3 of the oil separator 2 also contains refrigerant. Therefore, when the refrigerant oil is returned from the suction port G2 to the compressor 1 through the second oil return passage, the amount of refrigerant flowing to the load unit 201 side is reduced by the amount of refrigerant mixed in the refrigerant oil. As a result, the capacity of the refrigerating device 301 is lowered.
  • the refrigerating machine oil is returned to the intermediate portion inside the shell of the compressor 1. Therefore, when a compression section exists in an intermediate portion within the shell of the compressor 1, it is possible to sufficiently supply oil to the compression section.
  • the refrigerating machine oil supplied to the compression section is discharged from the compressor 1 together with the refrigerant in a gaseous state before it reaches the mechanical parts such as the motor shaft and bearings, the lubricity of the mechanical parts becomes insufficient. there is a possibility. This possibility is greater for low-pressure shell compressors, where the motor is located below the compression section.
  • compressors are classified into low-pressure shells and high-pressure shells.
  • the motor In the low-pressure shell, as described above, the motor is arranged below the compression section in the shell, which is a closed container. In the high pressure shell, the motor is positioned within the shell above the compression section.
  • the compressor 1 When the compressor 1 is configured with a high-pressure shell, since the compressed gaseous refrigerant passes through the shell, the refrigerating machine oil returned to the compressor 1 from the intermediate pressure port G3 spreads throughout the shell together with the gaseous refrigerant. . Therefore, when the compressor 1 is configured with a high-pressure shell, the supply of refrigerating machine oil to the mechanical parts largely depends on the refrigerating machine oil returning to the compressor 1 from the intermediate pressure port G3.
  • the compressor 1 when the compressor 1 is configured with a low-pressure shell, the compressed gaseous refrigerant is discharged from the compressor 1 without passing through the motor. Therefore, the refrigerating machine oil returned to the compressor 1 from the intermediate pressure port G3 may also be discharged from the compressor 1 together with the gaseous refrigerant without lubricating the motor. Therefore, when the compressor 1 is configured with a low-pressure shell, refrigerating machine oil is supplied to the mechanical parts from the oil tank provided at the bottom of the compressor 1 in addition to the refrigerating machine oil returning to the compressor 1 from the suction port G2. much depends on.
  • the compressor 1 Regardless of whether the compressor 1 is composed of a low-pressure shell or a high-pressure shell, when a liquid state refrigerant returns to the suction port G2 of the compressor 1, a so-called liquid backflow occurs.
  • the refrigerating machine oil returning from the suction port G2 side and the refrigerating machine oil in the oil tank are diluted with the liquid state refrigerant.
  • the concentration of the refrigerating machine oil in the compressor 1 is lowered.
  • mechanical components such as motors, shafts associated with motors, and bearings are poorly lubricated.
  • the heat source unit 101 returns the refrigerating machine oil from the intermediate pressure port G3 to the compressor 1 through the first oil return passage including part of the injection passage when no liquid back is generated.
  • the heat source unit 101 switches the oil return flow path from the first oil return flow path to the second oil return flow path when liquid backflow occurs due to load fluctuation during operation or frost formation on the evaporator. .
  • the refrigerating machine oil is returned to the compressor 1 from the suction port G2 through the second oil return flow path.
  • the heat source unit 101 returns the oil return channel from the second oil return channel to the first oil return channel when the liquid back is eliminated.
  • the three-way valve 40 is controlled by the control device 50.
  • the control device 50 switches the oil return flow path from the first oil return flow path to the second oil return flow path when liquid back is detected.
  • Control device 50 identifies the occurrence of liquid backflow by, for example, detecting that the degree of superheat (suction superheat) of the refrigerant sucked by compressor 1 has decreased.
  • Temperature sensor 71 and a first pressure sensor 72 are provided in the pipe 16 on the suction side of the compressor 1 .
  • Temperature sensor 71 is composed of, for example, an intake temperature thermistor.
  • a temperature sensor 71 detects the temperature of the refrigerant sucked by the compressor 1 .
  • the first pressure sensor 72 detects the pressure of refrigerant sucked by the compressor 1 .
  • the control device 50 calculates the intake superheat from the temperature difference between the saturation temperature corresponding to the pressure detected by the first pressure sensor 72 and the temperature detected by the temperature sensor 71, for example. Note that the control device 50 may detect liquid backflow based on a decrease in the degree of superheat of the refrigerant discharged from the compressor 1 .
  • the control device 50 includes a CPU (Central Processing Unit) 51, a memory 52, an input/output buffer (not shown) for inputting/outputting various signals, and the like.
  • the memory 52 includes ROM (Read Only Memory) and RAM (Random Access Memory).
  • the CPU 51 develops a program stored in the ROM into the RAM or the like and executes it.
  • the program stored in the ROM is a program in which processing procedures of the control device 50 are described.
  • the controller 50 controls each device in the heat source unit 101 according to these programs.
  • FIG. 2 is a flowchart for explaining the control of the control device 50 according to the first embodiment.
  • the control device 50 switches the oil return flow path between the first oil return flow path and the second oil return flow path by executing the processing of the flowchart described below.
  • the control device 50 determines whether liquid back is detected (step S11). Specifically, in step S11, the control device 50 determines that liquid back is present when the suction superheat is less than the first threshold.
  • the first threshold is, for example, 10K (Kelvin).
  • the control device 50 determines that liquid back has not occurred (YES in step S11)
  • the control device 50 controls the three-way valve 40 to change the oil return flow path from the second oil return flow path to the first oil return flow path. road (step S12).
  • the refrigerating machine oil and refrigerant discharged from the oil outlet P3 of the oil separator 2 return to the compressor 1 through the intermediate pressure port G3 through the oil return pipes 31 and 32 and the injection pipe 23 . Therefore, the refrigerant does not flow out to the low pressure (suction) side. As a result, it is possible to prevent the refrigerating capacity of the refrigerating device 301 from decreasing.
  • step S11 the control device 50 maintains the setting of the first oil return flow path.
  • the control device 50 determines that liquid back is occurring (NO in step S11)
  • the control device 50 controls the three-way valve 40 to change the oil return flow path from the first oil return flow path to the second oil return flow path. road (step S13).
  • the refrigerating machine oil and the refrigerant discharged from the oil outlet P3 of the oil separator 2 return to the compressor 1 through the suction port G2 through the oil return pipes 31, 33 and the pipe 16. Therefore, it is possible to prevent the concentration of the refrigerating machine oil from lowering due to liquid backflow. Further, heat exchange is performed between the liquid refrigerant and the high-temperature refrigerating machine oil, thereby promoting the evaporation of the liquid refrigerant and eliminating the liquid backflow state.
  • control device 50 maintains the setting of the second oil return flow path.
  • step S12 or step S13 the control device 50 ends the processing based on this flowchart.
  • control device 50 By controlling the three-way valve 40 in this manner, the control device 50 normally performs an operation that emphasizes the capacity and performance of the refrigerating device 301, and an operation that prioritizes the reliability of the compressor 1 when liquid backflow occurs. can be switched to
  • FIG. 3 is an overall configuration diagram of a refrigeration system 302 according to the second embodiment.
  • a refrigerating device 302 according to the second embodiment differs from the refrigerating device 301 according to the first embodiment in that a first flow control valve 61 is added to the oil return pipe 31 .
  • a refrigerating device 302 according to the second embodiment is the same as the refrigerating device 301 according to the first embodiment in terms of other configuration.
  • the first flow control valve 61 is, for example, an electronic expansion valve.
  • the heat source unit 102 according to the second embodiment includes a control device 50 like the heat source unit 101 according to the first embodiment.
  • the control device 50 controls the first flow control valve 61 in addition to the three-way valve 40 .
  • the control device 50 adjusts the amount of refrigerating machine oil returned from the oil separator 2 to the compressor 1 by controlling the degree of opening of the first flow control valve 61 according to the degree of liquid backflow. The details of control by the control device 50 will be described based on a flowchart.
  • FIG. 4 is a flowchart for explaining the control of the control device 50 according to the second embodiment.
  • the control device 50 determines whether liquid back is detected (step S21). When the control device 50 determines that liquid back has not occurred (YES in step S21), the control device 50 controls the three-way valve 40 to change the oil return flow path from the second oil return flow path to the first oil return flow path. road (step S22).
  • the control device 50 determines that there is no liquid back when the suction superheat is 10K or more, and determines that there is liquid back when the suction superheat is 10K or more. Further, by executing the process of step S22, the refrigerating machine oil and the refrigerant discharged from the oil outlet P3 of the oil separator 2 pass through the oil return pipes 31 and 32 and the injection pipe 23 and are compressed from the intermediate pressure port G3. Return to Aircraft 1.
  • the degree of opening of the first flow control valve 61 can be set to a constant size. For example, the degree of opening of the first flow control valve 61 may be the maximum degree of opening.
  • step S21 When the controller 50 determines that liquid back is occurring (NO in step S21), the control device 50 controls the three-way valve 40 to change the oil return flow path from the first oil return flow path to the second oil return flow path. road (step S23). As a result, the refrigerating machine oil and the refrigerant discharged from the oil outlet P3 of the oil separator 2 return to the compressor 1 through the suction port G2 through the oil return pipes 31, 33 and the pipe 16.
  • control device 50 maintains the setting of the second oil return flow path.
  • the control device 50 determines whether or not the degree of liquid backflow is light (step S24).
  • the degree of liquid backflow can be determined, for example, based on the magnitude of suction superheat. For example, if the magnitude of inhalation superheat is greater than or equal to the first threshold, it is determined that there is no liquid bagging, and if the magnitude of inhalation superheat is greater than or equal to the second threshold and less than the first threshold, it is determined that there is slight liquid bagging. If the magnitude of the inhalation superheat is less than the second threshold, it may be determined that there is severe liquid bagging.
  • the first threshold may be 10K and the second threshold may be 5K.
  • step S24 When the control device 50 determines that the degree of liquid backflow is light (YES in step S24), it reduces the opening of the first flow rate control valve 61 (step S25). On the other hand, when the controller 50 determines that the degree of liquid backflow is severe (NO in step S24), it increases the degree of opening of the first flow control valve 61 (step S26).
  • the control device 50 controls the opening degree of the first flow control valve 61 so that "first degree of opening>second degree of opening>third degree of opening" is satisfied.
  • the first degree of opening is the degree of opening of the first flow control valve 61 when liquid back is not occurring.
  • the second degree of opening is the degree of opening of the first flow control valve 61 when severe liquid backflow occurs.
  • the third degree of opening is the degree of opening of the first flow control valve 61 when a slight liquid backflow occurs.
  • the first to third opening degrees may be fixed values.
  • the first degree of opening may be a size that fully opens the first flow control valve 61 .
  • the opening degree set in steps S25 and S26 may be varied depending on the situation. For example, the control device 50 determines in step S24 that severe liquid backflow is occurring, and sets the opening degree of the first flow rate control valve 61 in step S26. After that, the control device 50 executes the processing based on the flowchart again. At this time, if it is determined in step S24 that a severe liquid backflow has occurred, the control device 50 increases the degree of opening of the first flow control valve 61 in step S26 even if the degree of opening is set above. good.
  • step S22 After step S22, step S25, or step S26, the control device 50 ends the processing based on this flowchart.
  • refrigerating machine oil returns to the compressor 1 from the suction port G2 when liquid backflow occurs.
  • the degree of opening of the first flow control valve 61 is adjusted according to the degree of liquid backflow. Specifically, when the degree of liquid backflow is large, the opening degree of the first flow rate control valve 61 increases, and when the degree of liquid backflow is small, the opening degree of the first flow rate control valve 61 decreases. As a result, when the degree of liquid backflow is large, more refrigerating machine oil returns to the compressor 1 from the suction port G2.
  • the degree of opening of the first flow rate adjustment valve 61 is adjusted according to the degree of liquid backflow, so the problem of the liquid backflow and the decrease in the concentration of the refrigerating machine oil can be solved.
  • An appropriate amount of refrigerating machine oil necessary for the operation can be returned to the suction port G2.
  • FIG. 5 is an overall configuration diagram of a refrigerating device 303 according to the third embodiment.
  • a refrigerating device 303 according to the third embodiment differs from the refrigerating device 302 according to the second embodiment in that a third oil return flow path is configured.
  • a refrigerating device 303 according to the third embodiment is the same as the refrigerating device 302 according to the second embodiment in terms of other configuration.
  • a refrigerating device 303 related to Embodiment 3 is provided with an oil return pipe 41 that connects the branch point b of the oil return pipe 33 and the pipe 15 that guides the refrigerant flowing from the load unit 201 to the accumulator 8 .
  • the third oil return flow path branches off from the branch point b of the oil return pipe 33 and is configured such that the refrigerating machine oil discharged from the oil separator 2 flows through the pipe 15 to the accumulator 8 .
  • a second flow control valve 62 is provided in the oil return pipe 41 .
  • the second flow control valve 62 is, for example, an electromagnetic valve.
  • the heat source unit 103 according to the third embodiment includes a control device 50, like the heat source unit 101 according to the first embodiment.
  • the control device 50 controls the second flow control valve 62 in addition to the three-way valve 40 and the first flow control valve 61 .
  • the control device 50 normally closes the second flow control valve 62 .
  • the control device 50 adjusts the amount of refrigerating machine oil returned from the oil separator 2 to the compressor 1 by controlling the degree of opening of the first flow control valve 61 according to the degree of liquid backflow.
  • the control device 50 opens the second flow control valve 62 when the opening degree of the first flow control valve 61 becomes equal to or greater than the reference opening degree. The details of control by the control device 50 will be described based on a flowchart.
  • FIG. 6 is a flow chart for explaining the control of the control device 50 according to the third embodiment.
  • the processing of steps S31 to S35 shown in FIG. 6 is the same as the processing of steps S21 to S25 of FIG. 4 described as the second embodiment. Therefore, their description will not be repeated here.
  • the control device 50 determines NO in step S34 when severe liquid backflow occurs. In this case, the controller 50 determines whether or not the degree of opening of the first flow control valve 61 is greater than or equal to the reference degree of opening (step S36). If the degree of opening of the first flow control valve 61 is less than the reference degree of opening (NO in step S36), the degree of opening of the first flow control valve 61 is increased (step S37).
  • step S37 the control device 50 returns to step S31 and repeats the process.
  • the control device 50 proceeds to step S34 again and determines that a severe liquid backflow has occurred, unless the opening degree of the first flow control valve 61 is equal to or greater than the reference opening degree, in step S37 the first The degree of opening of the flow control valve 61 is further increased.
  • the return amount of the refrigerating machine oil continues to increase, and eventually the opening of the first flow rate control valve 61 becomes equal to or larger than the preset reference opening.
  • the control device 50 opens the second flow regulating valve 62 (step S38).
  • a part of the refrigerating machine oil flowing through the oil return pipe 33 flows from the branch point b of the oil return pipe 33 through the oil return pipe 41 to the accumulator 8 when the control device 50 opens the second flow rate adjustment valve 62 .
  • the amount of refrigerating machine oil flowing from the oil return pipe 33 to the suction port G2 is reduced.
  • the refrigerating machine oil that has flowed into the accumulator 8 from the pipe 15 is held in the accumulator 8 . Therefore, the accumulator 8 also serves as an oil tank.
  • the high temperature refrigerating machine oil flowing from the oil return pipe 41 to the accumulator 8 exchanges heat with the refrigerant flowing through the main circuit including the pipe 15 .
  • the evaporation of the liquid refrigerant toward the suction port G2 is promoted.
  • liquid backflow can be eliminated. By eliminating liquid backflow, it is possible to prevent the concentration of the refrigerating machine oil from becoming too low on the suction side of the compressor 1 .
  • step S31 After opening the second flow control valve 62 in step S38, the control device 50 executes the process of step S31 again. If the degree of liquid backflow continues to be severe, NO is determined in step S34, and YES is determined in step S36. As a result, the open state of the second flow control valve 62 is maintained. Eventually, when the degree of liquid backing becomes mild, the control device 50 closes the second flow control valve 62 after executing the processes of steps S33 to S35 (step S39a). Further, when the liquid back is eliminated (YES in step S31), the control device 50 closes the second flow control valve 62 after executing the process of step S32 (step S39b). After step S39a or step S39b, the control device 50 ends the processing based on this flowchart.
  • the heat source unit 103 according to the third embodiment similarly to the heat source unit 102 according to the second embodiment, the degree of opening of the first flow control valve 61 is adjusted according to the degree of liquid backflow. Therefore, the heat source unit 103 according to the third embodiment can exhibit the same effect as the heat source unit 102 according to the second embodiment.
  • the heat source unit 103 when a severe liquid backflow occurs and the degree of opening of the first flow rate control valve 61 becomes equal to or greater than the reference degree of opening, the second flow rate control valve 62 A portion of the refrigerating machine oil is guided to the accumulator 8 by opening. As a result, it is possible to prevent more refrigerating machine oil from returning into the compressor 1 than necessary. Furthermore, by flowing high-temperature refrigerating machine oil through the circulation flow path including the accumulator 8, evaporation of the refrigerant in a liquid state is promoted, and liquid backflow can be eliminated.
  • Embodiment 3 a valve that can adjust the degree of opening in the same manner as the first flow rate adjustment valve 61 may be employed as the second flow rate adjustment valve 62 .
  • the control device 50 controls the opening of the second flow control valve 62 to the first opening until the opening of the first flow control valve 61 becomes equal to or greater than the reference opening.
  • the first degree of opening is zero. That is, the first flow control valve 61 is closed (fully closed).
  • the first degree of opening may be more than zero, but preferably close to the closed state.
  • the control device 50 changes the degree of opening of the second flow rate regulating valve 62 from the first degree of opening to a second degree of opening larger than the first degree of opening. degree control.
  • the second degree of opening is, for example, the degree of opening that fully opens the second flow control valve 62 .
  • the control device 50 does not immediately fully open the degree of opening of the second flow rate regulating valve 62, and adjusts the second flow rate step by step. You may control so that the opening degree of the valve 62 may be raised.
  • Embodiment 3 as shown in FIG. 5, the oil return pipe 41 and the pipe 15 are connected.
  • the oil return pipe 41 may be directly connected to the accumulator 8 . Even in this case, the temperature in the accumulator 8 rises due to the high-temperature refrigerating machine oil, thereby promoting the evaporation of the liquid refrigerant flowing through the main circuit.
  • FIG. 7 is an overall configuration diagram of a refrigerating device 304 according to the fourth embodiment.
  • a refrigerating device 304 according to the fourth embodiment differs from the refrigerating device 301 according to the first embodiment in that the compressor 1 is provided with an oil level sensor 74 .
  • a refrigerating device 304 according to the fourth embodiment is the same as the refrigerating device 301 according to the first embodiment in terms of other configuration.
  • the oil level sensor 74 detects the oil level height of the refrigerating machine oil in the compressor 1 .
  • Embodiment 4 is particularly useful when a low-pressure shell compressor is adopted as the compressor 1 .
  • a low-pressure shell compressor contains refrigerating machine oil in the shell.
  • the compressor of the low-pressure shell draws up the refrigerating machine oil due to the differential pressure and rotation of the shaft, and supplies the refrigerating machine oil to a drive section such as a motor and a compression section.
  • a drive section such as a motor and a compression section.
  • the heat source unit 104 according to the fourth embodiment includes a control device 50 like the heat source unit 101 according to the first embodiment.
  • a detection value of the oil level sensor 74 is input to the control device 50 . The details of control by the control device 50 will be described based on a flowchart.
  • FIG. 8 is a flow chart for explaining the control of the control device 50 according to the fourth embodiment.
  • the control device 50 determines whether or not the oil level in the compressor 1 is equal to or higher than a preset reference level (step S41).
  • Control device 50 specifies the height of the oil level in compressor 1 based on the detection value of oil level sensor 74 .
  • the reference height is a reference value for determining whether or not the inside of the compressor 1 is filled with refrigerating machine oil to a height at which a sufficient amount of refrigerating machine oil can be supplied to the compression section and the like.
  • a value for the reference height is set according to the size and type of the compressor 1 .
  • the memory 52 of the control device 50 stores the value of the reference height in advance.
  • step S41 When the control device 50 determines that the oil level in the compressor 1 is equal to or higher than the reference height (YES in step S41). By controlling the three-way valve 40, the oil return flow path is switched from the second oil return flow path to the first oil return flow path (step S42).
  • step S42 The processing of step S42 is the same as the processing of step S12 described using FIG. 2, so description thereof will not be repeated here.
  • control device 50 switches the oil return flow path to the first oil return flow path in order to operate the refrigeration cycle with high efficiency.
  • Refrigerant oil is returned to the compressor 1 from the intermediate pressure port G3 through the passage.
  • the control device 50 indirectly identifies with the oil level sensor 74 that the amount of oil in the shell has fallen below a certain amount.
  • the control device 50 determines that the oil level in the compressor 1 is not equal to or higher than the reference height (NO in step S41)
  • the control device 50 controls the three-way valve 40 to set the oil return flow path to the first return flow path.
  • the oil flow path is switched to the second oil return flow path (step S43).
  • step S43 the refrigerating machine oil returns to the compressor 1 through the suction port G2.
  • the amount of refrigerating machine oil returned into the shell increases.
  • the process of step S43 is the same as the process of step S13 described with reference to FIG. 2, so description thereof will not be repeated here.
  • the control device 50 ends the processing based on this flowchart.
  • the operation is normally performed with an emphasis on the capacity and performance of the refrigerating device 304, but when the amount of refrigerating machine oil is insufficient, It is possible to switch to an operation that prioritizes the reliability of the compressor 1 .
  • FIG. 9 is an overall configuration diagram of a refrigerating device 305 according to the fifth embodiment.
  • the refrigerating device 305 according to the fifth embodiment is implemented in that the pipe 11 connected to the discharge port G1 of the compressor 1 is provided with the second pressure sensor 73 and the oil level sensor 74 is not provided. It is different from the refrigerating device 304 related to form 4 of .
  • a refrigerating device 305 according to the fifth embodiment is the same as the refrigerating device 304 according to the fourth embodiment in terms of other configuration. Therefore, like the fourth embodiment, the fifth embodiment is particularly useful when applied to a low-pressure shell compressor.
  • the heat source unit 104 related to Embodiment 4 determines whether or not the amount of refrigerating machine oil in the compressor 1 is appropriate based on the detection value of the oil level sensor 74 .
  • the heat source unit 105 according to the fifth embodiment determines whether or not the amount of refrigerating machine oil in the compressor 1 is appropriate based on the magnitude of the input to the compressor 1 .
  • the magnitude of the input to the compressor 1 is, for example, the power consumption of the compressor 1.
  • the motor of the compressor 1 When the motor of the compressor 1 is driven while being immersed in the refrigerating machine oil, the rotational power of the motor increases due to the viscous resistance of the refrigerating machine oil. Therefore, as the amount of refrigerating machine oil filling the inside of the compressor 1 increases, the power consumption of the compressor 1 increases. Conversely, as the amount of refrigerating machine oil in the compressor 1 decreases, the viscous resistance of the refrigerating machine oil to the motor becomes weaker, so the power consumption of the compressor 1 becomes smaller. When the amount of refrigerating machine oil that fills the compressor 1 is insufficient and the height of the oil level is lower than the reference height, the power consumption of the compressor 1 becomes smaller than the power consumption corresponding to the reference height. .
  • the heat source unit 105 related to Embodiment 5 determines whether or not the amount of refrigerating machine oil in the compressor 1 is appropriate based on the power consumption of the compressor 1 .
  • the power consumption of the compressor 1 depends on the pressure on the suction side (low pressure side) of the compressor 1, the pressure on the discharge side (high pressure side) of the compressor 1, the temperature of the refrigerant sucked by the compressor 1, and the It can be calculated from the rotation speed or the like.
  • the first pressure sensor 72 detects pressure on the suction side of the compressor 1 .
  • a second pressure sensor 73 detects the pressure on the discharge side of the compressor 1 .
  • a temperature sensor 71 detects the temperature of the refrigerant sucked by the compressor 1 .
  • the control device 50 calculates the power consumption of the compressor 1 based on the detection values of these sensors and the rotation speed of the compressor 1 .
  • the power consumption of the compressor 1 when the appropriate amount of refrigerating machine oil is present in the compressor 1 is stored in advance as a reference power value. The details of control by the control device 50 will be described based on a flowchart.
  • FIG. 10 is a flow chart for explaining the control of the control device 50 according to the fifth embodiment.
  • the control device 50 determines whether or not the power consumption of the compressor 1 is greater than or equal to the reference power value stored in the memory 52 (step S51). When the power consumption of the compressor 1 is equal to or greater than the reference power value, it can be determined that a sufficient amount of refrigerating machine oil is present in the compressor 1 .
  • step S51 when the control device 50 determines that the power consumption of the compressor 1 is equal to or greater than the reference power value (YES in step S51).
  • the oil return flow path is switched from the second oil return flow path to the first oil return flow path (step S52).
  • the processing of step S52 is the same as the processing of step S12 described using FIG. 2, so description thereof will not be repeated here.
  • step S51 When the control device 50 determines that the power consumption of the compressor 1 is not equal to or greater than the reference power value (NO in step S51), the controller 50 controls the three-way valve 40 to divert the oil return flow path from the first oil return flow path. Switch to the second oil return flow path (step S53). This increases the amount of refrigerating machine oil returned into the shell. As a result, the lack of refrigerating machine oil in the compressor 1 is resolved.
  • step S53 The details of the processing of step S53 are the same as those of step S13 described with reference to FIG. 2, and thus the description thereof will not be repeated here.
  • step S52 or step S53 the control device 50 ends the processing based on this flowchart.
  • three-way valve 40 is controlled to normally operate with emphasis placed on the capacity and performance of refrigerating device 305, while when the amount of refrigerating machine oil is insufficient, It is possible to switch to an operation that prioritizes the reliability of the compressor 1 .
  • a refrigerating device 303 according to the third embodiment includes a first flow control valve 61 and a second flow control valve 62, as shown in FIG.
  • the refrigeration system 303 may be configured so as not to include the first flow rate control valve 61 and the second flow rate control valve 62 .
  • the refrigerating device 303 may be configured to include the first flow control valve 61 and not to include the second flow control valve 62 .
  • the refrigeration system 303 may be configured to include the second flow rate adjustment valve 62 without the first flow rate adjustment valve 61 .
  • the controller 50 controls the three-way valve 40 to switch the oil return flow path of the refrigerating machine oil between two flow paths.
  • One of the oil return flow paths is the first oil return flow path described in each embodiment.
  • the other oil return flow path is the second oil return flow path described in the third embodiment and the third oil return flow path branched from the second oil return flow path.
  • the first flow control valve 61 when the first flow control valve 61 is provided, the amount of refrigerating machine oil discharged from the oil separator 2 can be adjusted.
  • the control device 50 operates the second flow rate adjustment valve 62 according to the degree of liquid backing. It may be configured to determine whether or not to open. For example, the control device 50 closes the second flow control valve 62 if the degree of liquid backflow is mild. The control device 50 opens the second flow control valve 62 if the degree of liquid backflow is severe. At this time, the controller 50 may adjust the degree of opening of the second flow control valve 62 according to the degree of liquid backing.
  • the present disclosure is a heat source unit (101- 105).
  • the heat source unit is connected to the load unit to form a first flow path (11 to 16) through which the refrigerant circulates; a compressor (1) configured to draw refrigerant through a port (G3) and discharge refrigerant through a discharge port (G1); and a refrigerant inlet (P1) located downstream of the compressor in the first flow path , an oil separator (2) having a refrigerant outlet (P2) and an oil outlet (P3); a second heat exchanger (3) arranged downstream of the oil separator in the first flow path; A second flow path (21 to 23) branched from the first flow path downstream of the device and configured to return the refrigerant that has passed through the second heat exchanger from the intermediate pressure port to the compressor, and an oil separator A switching mechanism ( 40).
  • the refrigerating machine oil returns from the intermediate pressure port to the compressor through the second flow path.
  • the refrigerating machine oil returns
  • the switching mechanism switches the oil return flow path from the first oil return flow path to the second oil return flow path when liquid state refrigerant returns (liquid back) to the suction port (steps S13, S23 , S33).
  • the heat source unit further includes a first flow control valve (61) that adjusts the amount of refrigerating machine oil discharged from the oil outlet.
  • the heat source unit further comprises a control device (50) that controls the first flow control valve.
  • the control device adjusts the degree of opening of the first flow control valve according to the amount of liquid refrigerant returned (steps S24 to S26, steps S34 to S36).
  • control device determines the amount of liquid refrigerant returned (steps S24 and S34).
  • the heat source unit consists of an accumulator (8) arranged upstream of the compressor in the first flow path, and an accumulator (8) that branches off from the first oil return flow path so that the refrigerating machine oil discharged from the oil separator flows to the accumulator.
  • a third oil return flow path (41, 15) is further provided.
  • the heat source unit includes a first flow control valve (61) that adjusts the amount of refrigerating machine oil discharged from the oil outlet, and a second flow control valve that adjusts the flow rate of refrigerating machine oil to the third oil return flow path. and a valve (62).
  • the heat source unit further comprises a control device (50) that controls the first flow control valve and the second flow control valve, and the control device controls the opening of the first flow control valve to be equal to or greater than the reference opening. If so, the degree of opening of the second flow control valve is changed from the first degree of opening (eg, fully closed) to a second degree of opening larger than the first degree of opening (eg, fully open) (step S38).
  • the heat source unit is further equipped with an oil level sensor (74) that detects the level of the refrigerating machine oil inside the compressor, and the switching mechanism detects the level of the refrigerating machine oil as the reference level. When it becomes less than the value, the oil return flow path is switched from the first oil return flow path to the second oil return flow path (step S43).
  • the switching mechanism switches the oil return flow path from the first oil return flow path to the second oil return flow path when the power consumption of the compressor becomes less than the reference power value (step S53).

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Compressor (AREA)
PCT/JP2021/015864 2021-04-19 2021-04-19 熱源ユニット Ceased WO2022224304A1 (ja)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2025109720A1 (ja) * 2023-11-22 2025-05-30 三菱電機株式会社 冷凍サイクル装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06229634A (ja) * 1993-02-01 1994-08-19 Sanyo Electric Co Ltd 冷凍装置
JPH09292167A (ja) * 1996-04-26 1997-11-11 Mitsubishi Electric Corp アキュムレータ
JP2006112668A (ja) * 2004-10-12 2006-04-27 Fujitsu General Ltd 多室型空気調和機の室外機
JP2016099032A (ja) * 2014-11-19 2016-05-30 シャープ株式会社 暖房機、及び、空気調和機
WO2019026270A1 (ja) * 2017-08-04 2019-02-07 三菱電機株式会社 冷凍サイクル装置および熱源ユニット

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06229634A (ja) * 1993-02-01 1994-08-19 Sanyo Electric Co Ltd 冷凍装置
JPH09292167A (ja) * 1996-04-26 1997-11-11 Mitsubishi Electric Corp アキュムレータ
JP2006112668A (ja) * 2004-10-12 2006-04-27 Fujitsu General Ltd 多室型空気調和機の室外機
JP2016099032A (ja) * 2014-11-19 2016-05-30 シャープ株式会社 暖房機、及び、空気調和機
WO2019026270A1 (ja) * 2017-08-04 2019-02-07 三菱電機株式会社 冷凍サイクル装置および熱源ユニット

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2025109720A1 (ja) * 2023-11-22 2025-05-30 三菱電機株式会社 冷凍サイクル装置

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