WO2022064989A1 - 極低温冷凍機、および極低温冷凍機の監視方法 - Google Patents

極低温冷凍機、および極低温冷凍機の監視方法 Download PDF

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Publication number
WO2022064989A1
WO2022064989A1 PCT/JP2021/032255 JP2021032255W WO2022064989A1 WO 2022064989 A1 WO2022064989 A1 WO 2022064989A1 JP 2021032255 W JP2021032255 W JP 2021032255W WO 2022064989 A1 WO2022064989 A1 WO 2022064989A1
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WIPO (PCT)
Prior art keywords
motor
current
expander
operating frequency
ultra
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/JP2021/032255
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English (en)
French (fr)
Japanese (ja)
Inventor
孝明 森江
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.)
Sumitomo Heavy Industries Ltd
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Sumitomo Heavy Industries Ltd
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Filing date
Publication date
Application filed by Sumitomo Heavy Industries Ltd filed Critical Sumitomo Heavy Industries Ltd
Priority to JP2022551230A priority Critical patent/JP7796659B2/ja
Priority to EP21872120.7A priority patent/EP4220037A4/en
Priority to CN202180063640.5A priority patent/CN116324310A/zh
Publication of WO2022064989A1 publication Critical patent/WO2022064989A1/ja
Priority to US18/123,347 priority patent/US20230228472A1/en
Anticipated expiration legal-status Critical
Priority to JP2025278909A priority patent/JP2026042088A/ja
Ceased 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
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/06—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point using expanders
    • 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
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • 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
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/005—Arrangement or mounting of control or safety devices of safety devices
    • 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
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/14—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle
    • F25B9/145—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle pulse-tube 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
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1427—Control of a pulse tube
    • 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
    • F25B2500/26—Problems to be solved characterised by the startup of the refrigeration 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
    • F25B2600/00—Control issues
    • F25B2600/02—Compressor control
    • F25B2600/025—Compressor control by controlling speed
    • F25B2600/0253—Compressor control by controlling speed with variable speed
    • 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
    • F25B2700/15—Power, e.g. by voltage or current
    • 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
    • F25B2700/15—Power, e.g. by voltage or current
    • F25B2700/151—Power, e.g. by voltage or current of the compressor motor
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Definitions

  • the present invention relates to an ultra-low temperature freezer and a monitoring method for the ultra-low temperature refrigerator.
  • One of the exemplary objects of an aspect of the present invention is to provide an ultra-low temperature refrigerator and a monitoring method thereof that are useful for predicting or preventing abnormal operation or failure of an expander motor due to long-term operation.
  • an ultra-low temperature refrigerator capable of performing steady operation and cool-down operation prior to steady operation.
  • the ultra-low temperature refrigerating machine is configured to control the operating frequency of the inflator motor that operates the inflator of the ultra-low temperature refrigerating machine and the operating frequency of the inflator motor.
  • An inverter that can operate to drive the It is equipped with a processing unit for monitoring.
  • a method for monitoring an ultra-low temperature refrigerator can perform steady operation and cool-down operation prior to steady operation, and controls the operating frequency of the expander motor that operates the expander of the ultra-low temperature refrigerator and the operating frequency of the expander motor. It is equipped with an inverter that can operate to drive the expander motor at a lower operating frequency than the cooldown operation in steady operation.
  • the method comprises measuring the current supplied from the inverter to the expander motor and monitoring the expander motor at least based on the current of the expander motor in steady operation.
  • the cryogenic refrigerator comprises an expander motor that operates the expander of the cryogenic refrigerator, an inverter configured to control the operating frequency of the expander motor, and an inverter or expander motor. It is provided with a processing unit for monitoring an expander motor based on a power consumption signal indicating the power consumption of the inverter.
  • a method for monitoring an ultra-low temperature refrigerator includes an expander motor for operating the expander of the ultra-low temperature refrigerator and an inverter configured to control the operating frequency of the expander motor.
  • This method comprises acquiring the power consumption of an inverter or an expander motor and monitoring the expander motor based on the acquired power consumption.
  • an ultra-low temperature refrigerator and a monitoring method thereof which are useful for predicting or preventing abnormal operation or failure of an expander motor due to long-term operation.
  • FIG. 1 and 2 are diagrams schematically showing the ultra-low temperature refrigerator 10 according to the embodiment.
  • FIG. 1 shows the appearance of the ultra-low temperature freezer 10
  • FIG. 2 shows the internal structure of the ultra-low temperature refrigerator 10.
  • the ultra-low temperature refrigerator 10 is, for example, a two-stage Gifford-McMahon (GM) refrigerator.
  • GM Gifford-McMahon
  • the ultra-low temperature refrigerator 10 includes a compressor 12 and an expander 14. Although the details will be described later, the ultra-low temperature refrigerator 10 includes a monitoring device for monitoring the expander motor 42 for operating the expander 14, and this monitoring device includes a current sensor 50 and a processing unit 100.
  • the compressor 12 is configured to recover the working gas of the ultra-low temperature refrigerator 10 from the expander 14, pressurize the recovered working gas, and supply the working gas to the expander 14 again.
  • the working gas also referred to as a refrigerant gas, is usually helium gas, but other suitable gases may be used.
  • the pressure of the working gas supplied from the compressor 12 to the expander 14 and the pressure of the working gas recovered from the expander 14 to the compressor 12 are both considerably higher than the atmospheric pressure, and are the first high pressure and the first high pressure, respectively. It can be called the second high pressure.
  • the first high voltage and the second high voltage are also simply referred to as high voltage and low voltage, respectively.
  • the high pressure is, for example, 2-3 MPa.
  • the low pressure is, for example, 0.5 to 1.5 MPa, for example, about 0.8 MPa.
  • the direction in which the working gas flows is indicated by an arrow.
  • the compressor 12 includes a compressor main body 22 and a compressor housing 23 that houses the compressor main body 22.
  • the compressor 12 is also referred to as a compressor unit.
  • the compressor main body 22 is configured to internally compress the working gas sucked from the suction port and discharge it from the discharge port.
  • the compressor body 22 may be, for example, a scroll type, a rotary type, or another pump that boosts the working gas.
  • the compressor body 22 may be configured to discharge a fixed and constant working gas flow rate. Alternatively, the compressor main body 22 may be configured to have a variable flow rate of the working gas to be discharged.
  • the compressor body 22 is sometimes referred to as a compression capsule.
  • the compressor 12 may include a compressor controller 24 that controls the compressor 12.
  • the compressor controller 24 may not only control the compressor 12 but also the ultra-low temperature refrigerator 10 in an integrated manner, and may also control, for example, the expander 14 (for example, the expander motor 42). ..
  • the compressor controller 24 may be attached to the compressor 12, for example, may be installed on the outer surface of the compressor housing 23 and housed in the compressor housing 23. Alternatively, the compressor controller 24 may be located away from the compressor 12 and may be connected to the compressor 12 by, for example, a control signal line.
  • the expander 14 includes a refrigerator cylinder 16 and a displacer assembly 18.
  • the refrigerator cylinder 16 guides the linear reciprocating motion of the displacer assembly 18 and forms an expansion chamber (32, 34) for the working gas with the displacer assembly 18.
  • the expander 14 includes a pressure switching valve 40 that determines the timing of starting intake of the working gas into the expansion chamber and the timing of starting the exhaust of the working gas from the expansion chamber.
  • the side near the top dead center of the axial reciprocating movement of the displacer is "upper” and the side near the bottom dead center is “lower”. Will be written as.
  • the top dead center is the position of the displacer where the volume of the expansion space is maximum
  • the bottom dead center is the position of the displacer where the volume of the expansion space is minimum. Since a temperature gradient is generated in which the temperature drops from the upper side to the lower side in the axial direction during the operation of the ultra-low temperature refrigerator 10, the upper side can be called the high temperature side and the lower side can be called the low temperature side.
  • the refrigerator cylinder 16 has a first cylinder 16a and a second cylinder 16b.
  • the first cylinder 16a and the second cylinder 16b are members having a cylindrical shape, and the second cylinder 16b has a smaller diameter than the first cylinder 16a.
  • the first cylinder 16a and the second cylinder 16b are coaxially arranged, and the lower end of the first cylinder 16a is rigidly connected to the upper end of the second cylinder 16b.
  • the displacer assembly 18 includes a first displacer 18a and a second displacer 18b connected to each other, and these move together.
  • the first displacer 18a and the second displacer 18b are members having a cylindrical shape, and the second displacer 18b has a smaller diameter than the first displacer 18a.
  • the first displacer 18a and the second displacer 18b are arranged coaxially.
  • the first displacer 18a is housed in the first cylinder 16a, and the second displacer 18b is housed in the second cylinder 16b.
  • the first displacer 18a can reciprocate axially along the first cylinder 16a, and the second displacer 18b can reciprocate axially along the second cylinder 16b.
  • the first displacer 18a accommodates the first cold storage device 26.
  • the first cold storage device 26 is formed by filling a tubular main body of the first displacer 18a with a wire mesh such as copper or other appropriate first cold storage material.
  • the upper lid portion and the lower lid portion of the first displacer 18a may be provided as members separate from the main body portion of the first displacer 18a, and the upper lid portion and the lower lid portion of the first displacer 18a may be appropriately fastened, welded, or the like.
  • the first cold storage material may be accommodated in the first displacer 18a by being fixed to the main body by means.
  • the second displacer 18b houses the second cold storage 28.
  • the second cold storage device 28 is filled with a non-magnetic cold storage material such as bismuth, a magnetic cold storage material such as HoCu 2 , or any other appropriate second cold storage material in the tubular main body of the second displacer 18b. Is formed by.
  • the second cold storage material may be formed into granules.
  • the upper lid portion and the lower lid portion of the second displacer 18b may be provided as separate members from the main body portion of the second displacer 18b, and the lower lid portion of the upper lid portion of the second displacer 18b may be appropriately fastened, welded, or the like.
  • the second cold storage material may be accommodated in the second displacer 18b by being fixed to the main body by means.
  • the displacer assembly 18 forms a room temperature chamber 30, a first expansion chamber 32, and a second expansion chamber 34 inside the refrigerator cylinder 16.
  • the expander 14 comprises a first cooling stage 33 and a second cooling stage 35 for heat exchange with a desired object or medium to be cooled by the cryogenic refrigerator 10.
  • the room temperature chamber 30 is formed between the upper lid portion of the first displacer 18a and the upper portion of the first cylinder 16a.
  • the first expansion chamber 32 is formed between the lower lid portion of the first displacer 18a and the first cooling stage 33.
  • the second expansion chamber 34 is formed between the lower lid portion of the second displacer 18b and the second cooling stage 35.
  • the first cooling stage 33 is fixed to the lower part of the first cylinder 16a so as to surround the first expansion chamber 32
  • the second cooling stage 35 is fixed to the lower part of the second cylinder 16b so as to surround the second expansion chamber 34. Has been done.
  • the first cool storage device 26 is connected to the room temperature chamber 30 through the working gas flow path 36a formed in the upper lid portion of the first displacer 18a, and is connected to the room temperature chamber 30 through the working gas flow path 36b formed in the lower lid portion of the first displacer 18a. 1 It is connected to the expansion chamber 32.
  • the second regenerator 28 is connected to the first regenerator 26 through a working gas flow path 36c formed from the lower lid portion of the first displacer 18a to the upper lid portion of the second displacer 18b. Further, the second regenerator 28 is connected to the second expansion chamber 34 through the working gas flow path 36d formed in the lower lid portion of the second displacer 18b.
  • the working gas flow between the first expansion chamber 32, the second expansion chamber 34 and the room temperature chamber 30 is not the clearance between the refrigerator cylinder 16 and the displacer assembly 18, but the first cold storage 26 and the second cold storage.
  • a first seal 38a and a second seal 38b may be provided so as to be guided by the vessel 28.
  • the first seal 38a may be attached to the upper lid portion of the first displacer 18a so as to be arranged between the first displacer 18a and the first cylinder 16a.
  • the second seal 38b may be attached to the upper lid portion of the second displacer 18b so as to be arranged between the second displacer 18b and the second cylinder 16b.
  • the expander 14 includes a refrigerator housing 20 that houses the pressure switching valve 40.
  • the refrigerator housing 20 is coupled to the refrigerator cylinder 16 to form an airtight container that houses the pressure switching valve 40 and the displacer assembly 18.
  • the pressure switching valve 40 includes a high pressure valve 40a and a low pressure valve 40b, and is configured to generate periodic pressure fluctuations in the refrigerator cylinder 16.
  • the working gas discharge port of the compressor 12 is connected to the room temperature chamber 30 via the high pressure valve 40a, and the working gas suction port of the compressor 12 is connected to the room temperature chamber 30 via the low pressure valve 40b.
  • the high pressure valve 40a and the low pressure valve 40b are configured to selectively and alternately open and close (ie, when one is open, the other is closed).
  • the pressure switching valve 40 may take the form of a rotary valve. That is, the pressure switching valve 40 may be configured so that the high pressure valve 40a and the low pressure valve 40b are alternately opened and closed by the rotational sliding of the valve disk with respect to the stationary valve body. In that case, the expander motor 42 may be connected to the pressure switching valve 40 so as to rotate the valve disk of the pressure switching valve 40.
  • the pressure switching valve 40 is arranged so that the valve rotation axis is coaxial with the rotation axis of the expander motor 42.
  • the high pressure valve 40a and the low pressure valve 40b may be valves that can be individually controlled, and in that case, the pressure switching valve 40 may not be connected to the expander motor 42.
  • the expander 14 includes an expander motor 42 and a motion conversion mechanism 43.
  • the expander motor 42 is attached to the refrigerator housing 20.
  • the motion conversion mechanism 43 is housed in the refrigerator housing 20 like the pressure switching valve 40.
  • the expander motor 42 is connected to the displacer drive shaft 44 via a motion conversion mechanism 43 such as a Scotch yoke mechanism.
  • the motion conversion mechanism 43 converts the rotary motion output by the expander motor 42 into a linear reciprocating motion of the displacer drive shaft 44.
  • the displacer drive shaft 44 extends from the motion conversion mechanism 43 into the room temperature chamber 30, and is fixed to the upper lid portion of the first displacer 18a.
  • the rotation of the expander motor 42 is converted into an axial reciprocating motion of the displacer drive shaft 44 by the motion conversion mechanism 43, and the displacer assembly 18 reciprocates linearly in the refrigerator cylinder 16 in the axial direction.
  • the ultra-low temperature refrigerator 10 is supplied with power from a power source 46 such as a commercial power source (three-phase AC power source).
  • the power supply 46 is connected to the compressor 12 and the expander motor 42 by the power supply wiring 48. Since the inflator motor 42 is connected to the power supply 46 via the compressor 12, the compressor 12 can also be regarded as the power supply of the inflator motor 42.
  • the compressor 12 and the expander motor 42 may be connected to individual power sources.
  • the expander motor 42 is, for example, a permanent magnet type motor driven by three-phase alternating current.
  • the operating frequency of the expander motor 42 is controlled by the inverter 90.
  • the inverter 90 is installed on the power supply wiring 48.
  • the expander motor 42 can operate at a rotation speed corresponding to the operating frequency of the expander motor 42, which is equal to the output frequency of the inverter 90.
  • the output frequency of the inverter 90 can vary from 30 Hz to 100 Hz, or from 40 Hz to 70 Hz.
  • the current sensor 50 is connected to the expander motor 42 so as to measure the current supplied from the inverter 90 to the expander motor 42 at least in the steady operation of the ultra-low temperature refrigerator 10.
  • the current sensor 50 is installed on the power supply wiring 48 between the inverter 90 and the expander motor 42.
  • the current sensor 50 is configured to output a motor current signal S1 indicating the measured current to the processing unit 100.
  • the motor current signal S1 may represent an effective value of the current supplied to the expander motor 42.
  • the current sensor 50 is communicably connected to the processing unit 100 by wire or wirelessly.
  • the current sensor 50 may be a three-phase current meter that simultaneously measures the three-phase current flowing through the expander motor 42 at the same time, or is another type of current sensor that measures the current flowing through the expander motor 42. You may.
  • the current sensor 50 individually and simultaneously measures the three-phase currents output from the inverter 90 to the expander motor 42, and as the motor current signal S1, for example, a voltage signal indicating the magnitude of each of the measured three-phase currents. May be configured to be output to the processing unit 100.
  • the motor current signal S1 may be current waveform data indicating a time change of the current flowing through the expander motor 42 during the operation of the ultra-low temperature refrigerator 10.
  • the inverter 90 is configured to output the output frequency information S2 indicating the output frequency of the inverter 90 (that is, the operating frequency of the expander motor 42) to the processing unit 100.
  • the processing unit 100 may calculate the output frequency information S2 from the motor current signal S1 input from the current sensor 50.
  • the processing unit 100 may calculate the operating frequency of the expander motor 42 by counting the number of current peaks per unit time from the waveform of the current flowing through the expander motor 42.
  • the inverter 90 may include a current sensor 50 (the inverter 90 may have a function of measuring the output current), and the processing unit 100 may acquire the motor current signal S1 from the inverter 90.
  • the motor current signal S1 a signal of an effective value of the current output by the inverter 90 for controlling the expander motor 42 may be used.
  • the processing unit 100 is configured to receive the motor current signal S1 from the current sensor 50 (or the inverter 90) and monitor the expander motor 42 based on the motor current signal S1 in at least steady operation of the cryogenic refrigerator 10. There is. Details of the processing unit 100 will be described later.
  • the current sensor 50, the inverter 90, and the processing unit 100 are built in the compressor controller 24 and are provided in the compressor 12, but this is not the case.
  • the current sensor 50, the inverter 90, and the processing unit 100 may be provided in the expander 14, such as mounted on the expander motor 42, or may be provided in other places on the power supply wiring 48.
  • the ultra-low temperature refrigerator 10 When the compressor 12 and the expander motor 42 are operated, the ultra-low temperature refrigerator 10 generates periodic volume fluctuations and synchronous pressure fluctuations of the working gas in the first expansion chamber 32 and the second expansion chamber 34.
  • the intake step when the low pressure valve 40b is closed and the high pressure valve 40a is opened, the high pressure working gas flows from the compressor 12 into the room temperature chamber 30 through the high pressure valve 40a, and is the first through the first cool storage device 26. It is supplied to the 1 expansion chamber 32 and is supplied to the second expansion chamber 34 through the second cool storage device 28. In this way, the first expansion chamber 32 and the second expansion chamber 34 are boosted from low pressure to high pressure.
  • the displacer assembly 18 is moved up from the bottom dead center to the top dead center, and the volumes of the first expansion chamber 32 and the second expansion chamber 34 are increased.
  • the high pressure valve 40a is closed, the intake process ends.
  • the high pressure valve 40a When the high pressure valve 40a is closed and the low pressure valve 40b is opened, the high pressure first expansion chamber 32 and the second expansion chamber 34 are opened to the low pressure working gas suction port of the compressor 12, so that the working gas Expanded in the first expansion chamber 32 and the second expansion chamber 34, and as a result, the working gas having a low pressure becomes a chamber from the first expansion chamber 32 and the second expansion chamber 34 through the first cold storage 26 and the second cold storage 28. It is discharged to the greenhouse 30. At this time, the displacer assembly 18 is moved down from the top dead center to the bottom dead center, and the volumes of the first expansion chamber 32 and the second expansion chamber 34 are reduced. The working gas is recovered from the expander 14 to the compressor 12 through the low pressure valve 40b. The exhaust process ends when the low pressure valve 40b closes.
  • a refrigerating cycle such as a GM cycle is configured, and the first cooling stage 33 and the second cooling stage 35 are cooled to a desired ultra-low temperature.
  • the first cooling stage 33 can be cooled to a first cooling temperature in the range of, for example, about 20K to about 40K.
  • the second cooling stage 35 can be cooled to a second cooling temperature (for example, about 1K to about 4K) lower than the first cooling temperature.
  • the ultra-low temperature refrigerator 10 can perform steady operation and cool-down operation prior to steady operation.
  • the cool-down operation is an operation mode in which the ultra-low temperature refrigerator 10 is rapidly cooled from room temperature to an extremely low temperature when the ultra-low temperature refrigerator 10 is started, and the steady operation is the ultra-low temperature refrigerator 10 that maintains the state of being cooled to the extremely low temperature by the cool down operation. Operation mode.
  • the ultra-low temperature refrigerator 10 is cooled to a standard cooling temperature by a cool-down operation, and is maintained within an allowable temperature range of an extremely low temperature including this standard cooling temperature in a steady operation.
  • the standard cooling temperature varies depending on the application and setting of the ultra-low temperature refrigerator 10, but is typically about 4.2 K or less, for example, in the cooling application of a superconducting device. In some other cooling applications, the standard cooling temperature may be, for example, about 10K to 20K, or 10K or less.
  • the ultra-low temperature refrigerator 10 may include a temperature sensor 52 that measures the temperature of the second cooling stage 35 (and / or the first cooling stage 33) and outputs a measured temperature signal indicating the measured temperature.
  • the compressor controller 24 compares the measured temperature of the second cooling stage 35 with the standard cooling temperature (or the above-mentioned allowable temperature range) based on the measured temperature signal from the temperature sensor 52, and the measured temperature is higher than the standard cooling temperature. In that case, a cool-down operation may be executed, and if the measured temperature is equal to or lower than the standard cooling temperature, the cool-down operation may be shifted to the steady operation.
  • the inverter 90 can operate to drive the expander motor 42 at a lower operating frequency than the cool-down operation in steady operation.
  • the inverter 90 drives the expander motor 42 at a predetermined first operating frequency in the cool-down operation under the control of a controller (for example, the compressor controller 24), and the predetermined first operation in the steady operation.
  • the expander motor 42 may be driven at two operating frequencies. However, the second operating frequency is lower than the first operating frequency.
  • the controller may control the expander motor 42 based on the measured temperature signal from the temperature sensor 52 and a predetermined operating frequency profile, so that the operating frequency profile gives a higher operating frequency as the measured temperature is higher. It may be defined.
  • the controller may use the inverter 90 (eg, by feedback control such as PID control) to minimize the deviation of the measured temperature from the standard cooling temperature based on the measured temperature signal from the temperature sensor 52.
  • the output frequency of may be controlled. Therefore, when the measured temperature of the temperature sensor 52 is higher than the standard cooling temperature, the operating frequency of the expander motor 42 is increased, and when the measured temperature of the temperature sensor 52 is lower than the standard cooling temperature, the expander motor 42 The operating frequency is reduced. Therefore, in the cool-down operation, the initial measured temperature is room temperature, and at this time, the operating frequency of the expander motor 42 is considerably high, which enables rapid cooling. The operating frequency decreases as the temperature drops toward the standard cooling temperature.
  • the load applied to the expander motor 42 tends to gradually increase.
  • various fine particles derived from the lubricating oil and the cold storage material in the compressor 12 are accumulated in the expander 14, thereby increasing the pressure loss in the expander 14 and increasing the pressure loss in the expander 14, and the expansion chamber of the working gas.
  • the load applied to the expander motor 42 gradually increases in the long term due to the inflow and outflow to the expander motor 42.
  • moisture is absorbed by the displacer in the expander 14, whereby the displacer slightly expands in the expander 14, the clearance with the cylinder becomes small, and the sliding resistance of the displacer increases.
  • the inverter 90 By monitoring the current flowing through the expander motor 42 and detecting the abnormal fluctuation of the current due to the abnormality of the expander motor 42, it is possible to grasp the occurrence of the abnormality of the expander motor 42.
  • the operating frequency (rotational speed) of the expander motor 42 is controlled by the inverter 90, not only when an abnormality occurs in the expander motor 42 but also when the operating frequency is changed during normal operation.
  • the motor current fluctuates.
  • the motor current can fluctuate according to the magnitude of the magnetic field.
  • the motor current can also fluctuate when the input voltage to the inverter 90 fluctuates.
  • the motor current can fluctuate depending on various operating conditions of the expander motor 42, the current caused by the abnormal fluctuation of the current due to the abnormality of the expander motor 42 and the change of the operating conditions during the normal operation of the expander motor 42. It is not always easy to distinguish the fluctuation of.
  • FIG. 3 is a graph showing the results of measuring the relationship between the effective value of the current flowing through the expander motor 42 and the load duty for the values of a plurality of operating frequencies.
  • the vertical axis shows the effective value of the current supplied from the inverter 90 to the expander motor 42 and measured by the current sensor 50.
  • the load duty shown on the horizontal axis indicates the ratio (%) of the load torque actually applied to the expander motor 42 to the maximum load torque (for example, instantaneous maximum torque) allowed for the expander motor 42. Therefore, when the load duty exceeds 100%, it is highly probable that an abnormal operation such as step-out actually occurs in the expander motor 42.
  • the motor current values are about the same at 40 Hz and 50 Hz operating frequencies. It is controlled by an inverter. As described above, when the value of the operating frequency is relatively low, the motor current value has almost no dependence on the operating frequency. On the other hand, in the example of FIG. 3, the operating frequency is in the range of 50 Hz to 70 Hz, and the motor current value decreases as the operating frequency value increases. As described above, when the value of the operating frequency is relatively high, the motor current value is dependent on the operating frequency, and the motor current value may differ depending on the value of the operating frequency.
  • the motor current value when the load duty is smaller than 100% and sufficiently large (for example, 90% to 98%) can be used as the current threshold value.
  • the expander motor 42 When a current exceeding this current threshold flows through the expander motor 42 (that is, when measured by the current sensor 50), the expander motor 42 is loaded with a large load corresponding to the load duty. This is regarded as a prediction of the occurrence of abnormal operation of the expander motor 42, and measures are taken to prevent the occurrence of abnormal operation such as issuing a warning, lowering the operating frequency, and stopping the operation of the ultra-low temperature refrigerator 10. can do.
  • the motor current value when the expander motor 42 is driven at a higher operating frequency value (eg 70 Hz), the motor current value will be significantly smaller than at 60 Hz above, to the current threshold set for 60 Hz. Does not reach. Therefore, even if the motor current value in the 70 Hz operation of the expander motor 42 is compared with the threshold value for 60 Hz, no effective result can be obtained for predicting the occurrence of an abnormality in the expander motor 42. Conversely, when the expander motor 42 is driven at a lower operating frequency value (eg 50Hz), the motor current value will be significantly higher than at 60Hz described above, even with a significantly smaller load duty. , The current threshold set for 60 Hz will be exceeded. After all, even if the motor current value in the 50 Hz operation of the expander motor 42 is compared with the threshold value for 60 Hz, no effective result can be obtained for predicting the occurrence of an abnormality in the expander motor 42.
  • a lower operating frequency value eg 50Hz
  • a current threshold value is set for each of a plurality of values of the operating frequency of the expander motor 42.
  • FIG. 4 illustrates such a plurality of current thresholds.
  • FIG. 4 shows an example of the relationship between the operating frequency of the expander motor 42 and the current threshold value according to the embodiment.
  • FIG. 4 shows the relationship between the motor current value and the load duty according to the operating frequency shown in FIG. 3 for a specific load duty value (specifically, load duty 90% and 95%). be. Therefore, as described above, when the operating frequency is relatively low (in the operating frequency range of 40 Hz to 50 Hz in FIG. 4), the motor current value is almost constant. When the operating frequency is relatively high (in the operating frequency range of 50 Hz to 70 Hz in FIG. 4), the motor current value decreases as the operating frequency value increases. As can be seen from FIG. 4, as the load duty value increases, the motor current value increases.
  • the relationship between the operating frequency of the expander motor 42 and the current threshold value shown in FIG. 4 may be used as an example of the operating frequency / current threshold value table 62 described later.
  • the combination of the operating frequency value and the measured motor current value is in the region above the graph (that is, the expander motor 42 is driven at the operating frequency, the current value measured by the current sensor 50 at this time.
  • the current threshold value corresponding to the operating frequency is exceeded
  • it can be considered that the occurrence of abnormal operation of the expander motor 42 is predicted.
  • the combination of the operating frequency value and the measured motor current value is in the region below the graph, the measured current value does not exceed the current threshold value, so it can be considered that no abnormality occurs. can.
  • the expander 14 may be installed and used in a strong magnetic field environment.
  • the external magnetic field acting on the inflator motor 42 affects the operation of the inflator motor 42 and may fluctuate the current flowing through the inflator motor 42.
  • the motor current value tends to increase as the external magnetic field increases under a given load duty at a given operating frequency.
  • the expander motor 42 is a permanent magnet type motor, this tendency tends to occur.
  • the motor current value is, for example, about 5% when the external magnetic field is 500 gauss compared to the case where the external magnetic field is 0 gauss. Can increase by ⁇ 10%.
  • the input voltage from the power supply 46 to the inverter 90 is allowed to fluctuate to some extent (for example, about ⁇ 10%). Even if the input voltage to the inverter 90 fluctuates, the current flowing through the expander motor 42 may fluctuate. According to the present inventor's study, the motor current value is from a voltage value lower than the specified voltage value (for example, 200 V) of the power supply 46 under a given load duty at a given operating frequency to this specified voltage value. As the input voltage increases, it tends to increase.
  • the specified voltage value for example, 200 V
  • FIG. 5 is a block diagram of the motor monitoring device according to the embodiment.
  • This monitoring device includes a processing unit 100, and the processing unit 100 includes a current threshold value setting unit 60 and a comparison unit 70.
  • the current threshold setting unit 60 includes an operating frequency / current threshold table 62, an external magnetic field / current threshold table 64, and an input voltage / current threshold table 66.
  • the monitoring device may include a notification means 80 for visually notifying information indicating a monitoring result, and the notification means 80 may include, for example, a display 82.
  • the notification means 80 may notify the diagnosis result by voice such as a speaker.
  • the notification means 80 may transmit the diagnosis result to a remote device via a network such as the Internet.
  • the processing unit 100 is configured to monitor the expander motor 42 based on at least the motor current signal S1 in steady operation. Therefore, the processing unit 100 acquires information indicating the current operation mode of the ultra-low temperature refrigerator 10 from the controller (for example, the compressor controller 24), or based on the measured temperature signal S3 from the temperature sensor 52, the current operation mode. May be determined, and the expander motor 42 may be monitored based on the motor current signal S1 when the current operation mode is steady operation. In addition to or instead of this, the processing unit 100 may monitor the expander motor 42 based on the motor current signal S1 when the current operation mode is the cool-down operation.
  • the controller for example, the compressor controller 24
  • the processing unit 100 may monitor the expander motor 42 based on the motor current signal S1 when the current operation mode is the cool-down operation.
  • the processing unit 100 acquires the current threshold value Th based on the operating conditions of the expander motor 42, and sets the current of the expander motor 42 (for example, the effective value of the current) based on the motor current signal S1 to the current threshold value Th. It is configured to monitor the expander motor 42 by comparing with. Therefore, the current threshold setting unit 60 uses the current threshold of at least one of the operating frequency / current threshold table 62, the external magnetic field / current threshold table 64, and the input voltage / current threshold table 66. Using the table, the current threshold Th is acquired based on the operating conditions of the expander motor 42 (for example, motor current signal S1, output frequency information S2, magnitude of external magnetic field, input voltage to inverter 90, etc.). do.
  • the operating frequency / current threshold table 62 associates a plurality of current thresholds with a plurality of values of the operating frequency of the expander motor 42, and the external magnetic field / current threshold table 64 corresponds to the plurality of values of the operating frequency of the expander motor 42.
  • a plurality of current thresholds are associated with a plurality of values of the external magnetic field applied to the 42, and the input voltage / current threshold table 66 includes a plurality of current thresholds for the plurality of values of the input voltage to the inverter 90. The values are associated with each other.
  • the operating frequency / current threshold table 62, the external magnetic field / current threshold table 64, and the input voltage / current threshold table 66 are preset and stored in the processing unit 100. These current threshold tables can be appropriately set based on the empirical knowledge of the designer or experiments and simulations by the designer.
  • the current threshold value setting unit 60 acquires the current threshold value Th corresponding to the operating frequency value based on the operating frequency / current threshold value table 62 and the operating frequency value of the expander motor 42. It is composed of.
  • the operating frequency / current threshold table 62 includes at least a part of the operating frequency range of the expander motor 42 that can be controlled by the inverter 90 (for example, a region on the high frequency side of the range). ), A plurality of current thresholds may be associated with a plurality of values of the operating frequency of the expander motor 42 so that the current threshold decreases as the operating frequency increases.
  • the operating frequency / current threshold table 62 for each of the plurality of values of the operating frequency of the expander motor 42, a load torque that is a predetermined amount smaller than the maximum load torque allowed for the expander motor 42 expands.
  • the current value of the expander motor 42 under the value of the operating frequency may be associated with the value of the operating frequency as the current threshold value. ..
  • the load duty of a predetermined value may be selected from, for example, a range of 80% or more and less than 100%, or a range of 90% or more and 98% or less.
  • a plurality of operating frequency / current threshold tables 62 may be preset, and each of the plurality of operating frequency / current threshold tables 62 may be associated with a plurality of different load duty values.
  • the current threshold setting unit 60 sets the operating frequency of the operating frequency based on the operating frequency / current threshold table 62 selected from the plurality of operating frequencies / current threshold tables 62 and the operating frequency values of the expander motor 42.
  • the current threshold Th corresponding to the value may be acquired.
  • the current threshold setting unit 60 acquires the current threshold Th corresponding to the value of the external magnetic field based on the value of the external magnetic field / current threshold table 64 and the external magnetic field applied to the expander motor 42. It may be configured.
  • the value of the external magnetic field may be measured by a magnetic field sensor 54 mounted on or in the vicinity of the cryogenic refrigerator 10 (for example, the expander 14), and the measured value of the external magnetic field is the value of the processing unit 100. It may be input to and used by the current threshold setting unit 60.
  • the processing unit 100 acquires an estimated value of the external magnetic field applied to the expander motor 42 based on the motor current signal S1, and obtains an estimated value of the external magnetic field applied to the external magnetic field / current threshold table 64 and the expander motor 42. It may be configured to acquire the current threshold Th corresponding to the estimated value of the external magnetic field based on.
  • the three-phase current waveform flowing through the expander motor 42 has symmetry if the external magnetic field does not work or the external magnetic field is sufficiently small, whereas the three-phase current waveform increases as the external magnetic field increases. The asymmetry of the current waveform tends to increase.
  • Examples of this asymmetry include deviation of the peak value of the current waveform among the three phases (U phase, V phase, and W phase).
  • the asymmetry of the current waveform according to the external magnetic field may increase due to the generation of the unbalanced current.
  • external magnetic field origin parameters that can be calculated from the motor current signal S1 such as the maximum or minimum of the peaks of the U-phase, V-phase, and W-phase current waveforms, or the difference between the maximum and minimum values.
  • An estimated value of the external magnetic field of the expander motor 42 can be obtained from the motor current signal S1.
  • the current threshold setting unit 60 is configured to acquire the current threshold Th corresponding to the value of the input voltage based on the value of the input voltage / current threshold table 66 and the input voltage to the inverter 90. You may. Information indicating the value of the input voltage to the inverter 90 may be input from the inverter 90 to the processing unit 100 and used by the current threshold value setting unit 60.
  • a plurality of external magnetic field / current threshold table 64s may be preset, and each of the plurality of external magnetic field / current threshold tables 64 may be associated with a plurality of different operating frequency values. That is, for example, the first and second external magnetic field / current threshold tables 64 are preset, and the first external magnetic field / current threshold table 64 is set to the value of the first operating frequency (for example, 70 Hz). Used when the expander motor 42 is driven, the second external magnetic field / current threshold table 64 expands at a second operating frequency value (eg 60 Hz) that is different from the first operating frequency value. It may be used when the machine motor 42 is driven.
  • a plurality of input voltage / current threshold tables 66 may be preset, and each of the plurality of input voltage / current threshold tables 66 may be associated with a plurality of different operating frequency values. good.
  • the comparison unit 70 compares the current of the expander motor 42 (for example, the effective value of the current) with the acquired current threshold value Th based on the motor current signal S1, and generates monitoring result data D1 based on the comparison result. do.
  • the monitoring result data D1 is sent to the notification means 80, and the monitoring result is notified to the user by displaying the monitoring result, for example, on the display 82.
  • the notification means 80 may notify the user with an alarm sound. Instead of notifying immediately (or at the same time as notifying) in this way, the monitoring result data D1 may be stored in the processing unit 100 so that it can be presented to the user as needed.
  • the internal configuration of the processing unit 100 is realized by elements and circuits such as a computer CPU and memory as a hardware configuration, and is realized by a computer program or the like as a software configuration, but in the figure, it is appropriately linked by them. It is drawn as a functional block to be realized. It is understood by those skilled in the art that these functional blocks can be realized in various forms by combining hardware and software.
  • the processing unit 100 can be implemented by combining a processor (hardware) such as a CPU (Central Processing Unit) or a microcomputer and a software program executed by the processor (hardware).
  • a hardware processor may be configured by a programmable logic device such as an FPGA (Field Programmable Gate Array), or may be a control circuit such as a programmable logic controller (PLC).
  • the software program may be a computer program for causing the processing unit 100 to monitor the ultra-low temperature refrigerator 10.
  • FIG. 6 is a flowchart showing a monitoring method of the ultra-low temperature refrigerator 10 according to the embodiment.
  • the current supplied from the inverter 90 to the expander motor 42 is measured by the current sensor 50 during the operation of the ultra-low temperature refrigerator 10 (for example, during steady operation) (S10).
  • the expander motor 42 is monitored at least based on the current of the expander motor 42 in steady operation (S20).
  • the current threshold Th is acquired based on the operating conditions of the expander motor 42 (for example, motor current signal S1, output frequency information S2, magnitude of external magnetic field, input voltage to inverter 90, etc.). (S21).
  • the measured current value of the expander motor 42 is compared with the acquired current threshold Th (S22).
  • the comparison unit 70 determines that the occurrence of abnormal operation of the expander motor 42 is predicted (S23), and monitoring result data indicating that fact.
  • the comparison unit 70 determines that the occurrence of abnormal operation of the expander motor 42 is not predicted (S24), and monitors the monitoring result data D1 indicating that. Output. In this way, this monitoring method is completed.
  • the controller of the ultra-low temperature refrigerator 10 lowers the operating frequency of the expander motor 42, for example, issuing a warning.
  • the operation of the ultra-low temperature refrigerator 10 may be stopped, or other measures may be taken to prevent the occurrence of abnormal operation.
  • the processing unit 100 periodically and repeatedly executes such monitoring. Since the increase in the drive load of the expander motor 42 is a long-term phenomenon that gradually progresses over a long span, this monitoring method is practical if it is performed occasionally during the operation of the ultra-low temperature refrigerator 10 (for example, during steady operation). It is enough. Alternatively, the monitoring method may be constantly and repeatedly performed during the operation of the ultra-low temperature refrigerator 10.
  • the current supplied from the inverter 90 to the expander motor 42 is measured, and the expander is at least based on the current of the expander motor 42 in steady operation (for example, the effective value of the current).
  • the motor 42 By monitoring the motor 42, it is possible to predict or prevent abnormal operation or failure of the expander motor 42 due to long-term operation.
  • the ultra-low temperature refrigerator 10 may eventually fail. If it breaks down, stop the operation of the cryogenic system (for example, superconducting equipment or MRI system) that uses the cryogenic refrigerator 10 until maintenance such as repair of the cryogenic refrigerator or replacement with a new one is completed. I have no choice but to do so. In the case of a sudden failure, the time required for recovery tends to be relatively long.
  • cryogenic system for example, superconducting equipment or MRI system
  • the embodiment it is possible to monitor the expander motor 42 and notify the user of the ultra-low temperature refrigerator 10 or the service person who maintains the ultra-low temperature refrigerator 10 of the monitoring result. Based on the monitoring results, it is possible to take measures to minimize the impact on the operation of the ultra-low temperature system.
  • the output voltage from the inverter 90 may be different from the input voltage to the inverter 90.
  • the inverter 90 may have a function of limiting the output voltage to the specified voltage value when the input voltage exceeds the specified voltage value (for example, 200 V).
  • the inverter 90 may not have a boosting function. In this case, if the input voltage is less than the specified voltage value, the input voltage and the output voltage are equal, but if the input voltage exceeds the specified voltage value, the input voltage and the output voltage are different (the output voltage is smaller than the input voltage). Become).
  • the input voltage and the output voltage may differ depending on the control method of the motor operating frequency by the inverter 90. For example, in a typical Vf control, even if the input voltage is a specified voltage value, the output voltage may be lower than this specified voltage value depending on the operating frequency.
  • the output voltage is used as an example of the parameters referenced to set the current threshold. May be done.
  • FIG. 7 is a block diagram of the motor monitoring device according to the embodiment.
  • the monitoring device includes a processing unit 100 configured to monitor the expander motor 42 based on the motor current signal S1 from the current sensor 50.
  • the processing unit 100 may monitor the expander motor 42 at least in steady operation of the cryogenic refrigerator 10.
  • the monitoring device may include a notification means 80 for notifying information indicating a monitoring result, and the notification means 80 may include, for example, a display 82.
  • the processing unit 100 acquires the current threshold value Th based on the operating conditions of the expander motor 42, and sets the current of the expander motor 42 (for example, the effective value of the current) based on the motor current signal S1 to the current threshold value Th. It is configured to monitor the expander motor 42 by comparing with.
  • the processing unit 100 includes a current threshold value setting unit 60 and a comparison unit 70.
  • the current threshold value setting unit 60 includes an operating frequency / current threshold value table 62 and an output voltage / current threshold value table 68.
  • the operating frequency / current threshold table 62 associates a plurality of current thresholds with a plurality of values of the operating frequency of the expander motor 42, and the output voltage / current threshold table 68 is from the inverter 90.
  • a plurality of current threshold values are associated with a plurality of values of the output voltage of. These current threshold values are preset and stored in the processing unit 100. These current threshold tables can be appropriately set based on the empirical knowledge of the designer or experiments and simulations by the designer.
  • the current threshold value setting unit 60 acquires the current threshold value Th corresponding to the operating frequency value based on the operating frequency / current threshold value table 62 and the operating frequency value of the expander motor 42. It is composed of.
  • the inverter 90 is configured to output the output frequency information S2 indicating the value of the output frequency of the inverter 90 (that is, the operating frequency of the expander motor 42) to the processing unit 100.
  • the current threshold value setting unit 60 is configured to acquire the current threshold value Th corresponding to the value of the output voltage based on the value of the output voltage from the output voltage / current threshold value table 68 and the inverter 90. You may. Information indicating the value of the output voltage from the inverter 90 may be input from the inverter 90 to the processing unit 100 and used by the current threshold value setting unit 60.
  • the inverter 90 is configured to output an output voltage signal S4 indicating the value of the output voltage of the inverter 90 (that is, the input voltage to the expander motor 42) to the processing unit 100 in addition to the output frequency information S2. May be good.
  • a plurality of output voltage / current threshold tables 68 may be preset, and each of the plurality of output voltage / current threshold tables 68 may be associated with a plurality of different operating frequency values.
  • the first and second output voltage / current threshold tables 68 are preset, and the first output voltage / current threshold table 68 is an expander with a value of the first operating frequency (for example, 70 Hz).
  • the second output voltage / current threshold table 68 is an expander motor with a second operating frequency value (eg 60 Hz) that is different from the first operating frequency value. It may be used when 42 is driven.
  • the comparison unit 70 compares the current of the expander motor 42 (for example, the effective value of the current) with the acquired current threshold value Th based on the motor current signal S1, and generates monitoring result data D1 based on the comparison result. do. Similar to the embodiment described with reference to FIG. 5, the monitoring result data D1 is sent to the notification means 80, and the monitoring result is notified to the user by displaying the monitoring result, for example, on the display 82.
  • monitoring based on the motor current is described as an example, but monitoring based on the power consumption of the inverter 90 or the expander motor 42 is also possible. Such embodiments are described below.
  • FIG. 8 is a graph showing the relationship between the power consumption of the inverter 90 and the load duty for a plurality of operating frequency values. This graph is based on the measurement results by the present inventor.
  • the vertical axis shows the value of the power consumption of the inverter 90.
  • the horizontal axis shows the load duty of the expander motor 42, as in FIG.
  • the power consumption value tends to increase as the load duty increases. Therefore, for a certain operating frequency value (for example, 60 Hz), the power consumption value when the load duty is smaller than 100% and sufficiently large (for example, 90% to 98%) can be used as the power consumption threshold value.
  • the power consumption of the inverter 90 or the expander motor 42
  • the expander motor 42 is loaded with a large load corresponding to the load duty. This is regarded as a prediction of the occurrence of abnormal operation of the expander motor 42, and measures are taken to prevent the occurrence of abnormal operation such as issuing a warning, lowering the operating frequency, and stopping the operation of the ultra-low temperature refrigerator 10. can do.
  • the power consumption value depends on the operating frequency of the expander motor 42. As shown in FIG. 8, when the operating frequencies are 50 Hz and 60 Hz, the power consumption values indicating the same load duty are different. Therefore, in the embodiment, the power consumption threshold value is set for each of the plurality of values of the operating frequency of the expander motor 42.
  • the external magnetic field may increase or decrease the current flowing through the expander motor 42, as described above.
  • the external magnetic field may bring about a similar increase or decrease in power consumption.
  • the amount of change in the power consumption value when the load duty changes by a certain unit amount is the amount of change in the motor current when the load duty changes by a unit amount.
  • the apparent load duty change corresponding to the change in the power consumption value caused by the external magnetic field of a certain magnitude is larger than the apparent load duty change corresponding to the change in the motor current caused by the external magnetic field of the same magnitude. Also tends to be small. Therefore, in monitoring the expander motor 42 based on power consumption, the influence of the external magnetic field can be made relatively small.
  • the relationship between the power consumption value and the load duty is closer to linear than the relationship between the motor current value and the load duty shown in FIG. Therefore, there is an advantage that it is easy to monitor the operating condition in a region where the load duty is relatively small.
  • FIG. 9 is a block diagram of a motor monitoring device according to another embodiment.
  • the monitoring device includes a processing unit 100 that monitors the expander motor 42 based on the power consumption signal S5 indicating the power consumption of the inverter 90.
  • the inverter 90 may be configured to output a power consumption signal S5 indicating the power consumption of the inverter 90 to the processing unit 100 in addition to the output frequency information S2 and the output voltage signal S4, and the processing unit 100 may output the inverter 90.
  • the expander motor 42 is monitored based on the power consumption signal S5 output from the inverter.
  • the monitoring device may include a notification means 80 for notifying information indicating a monitoring result, and the notification means 80 may include, for example, a display 82.
  • the processing unit 100 acquires the power consumption threshold Th2 based on the operating conditions of the expander motor 42, and compares the power consumption value of the inverter 90 with the power consumption threshold Th2 based on the power consumption signal S5. Monitor the inflator motor 42.
  • the processing unit 100 includes a power consumption threshold setting unit 61 and a comparison unit 70.
  • the power consumption threshold setting unit 61 includes an operating frequency / power consumption threshold table 63 and an output voltage / power consumption threshold table 69.
  • the operating frequency / power consumption threshold table 63 associates a plurality of power consumption thresholds with a plurality of values of the operating frequency of the expander motor 42, and the output voltage / power consumption threshold table 69 includes the output voltage / power consumption threshold table 69.
  • a plurality of power consumption thresholds are associated with a plurality of values of the output voltage from the inverter 90. These power consumption threshold values are preset and stored in the processing unit 100. These power consumption threshold tables can be appropriately set based on the empirical knowledge of the designer or experiments and simulations by the designer.
  • the power consumption threshold setting unit 61 sets the power consumption threshold Th2 corresponding to the value of the operating frequency based on the operating frequency / power consumption threshold table 63 and the value of the operating frequency of the expander motor 42. Configured to get.
  • the inverter 90 is configured to output the output frequency information S2 indicating the value of the output frequency of the inverter 90 (that is, the operating frequency of the expander motor 42) to the processing unit 100.
  • the load torque that is a predetermined amount smaller than the maximum load torque allowed for the expander motor 42 is the expander.
  • the value of the operating frequency is set to the power consumption value of the inverter 90 (or the expander motor 42) under the value of the operating frequency. May be associated with.
  • the load duty of a predetermined value may be selected from, for example, a range of 80% or more and less than 100%, or a range of 90% or more and 98% or less.
  • a plurality of operating frequencies / power consumption threshold tables 63 may be preset, and each of the plurality of operating frequencies / power consumption threshold tables 63 may be associated with a plurality of different load duty values. ..
  • the power consumption threshold setting unit 61 is based on the operating frequency / power consumption threshold table 63 selected from the plurality of operating frequencies / power consumption threshold tables 63 and the operating frequency values of the expander motor 42.
  • the power consumption threshold Th2 corresponding to the value of the operating frequency may be acquired.
  • the power consumption threshold setting unit 61 acquires the power consumption threshold Th2 corresponding to the output voltage value based on the output voltage / power consumption threshold table 69 and the value of the output voltage from the inverter 90. It may be configured in.
  • the inverter 90 may be configured to output an output voltage signal S4 indicating the value of the output voltage of the inverter 90 (that is, the input voltage to the expander motor 42) to the processing unit 100 in addition to the output frequency information S2. ..
  • a plurality of output voltage / power consumption threshold tables 69 may be preset, and each of the plurality of output voltage / power consumption threshold tables 69 may be associated with a plurality of different operating frequency values. ..
  • the first and second output voltage / power consumption threshold tables 69 are preset, and the first output voltage / power consumption threshold table 69 is set to the value of the first operating frequency (for example, 70 Hz).
  • the second output voltage / power consumption threshold table 69 has a second operating frequency value (for example, 60 Hz) different from the first operating frequency value. It may be used when the expander motor 42 is driven.
  • the comparison unit 70 compares the power consumption value of the inverter 90 with the acquired power consumption threshold value Th2 based on the power consumption signal S5, and generates monitoring result data D1 based on the comparison result. Similar to the embodiment described with reference to FIG. 5, the monitoring result data D1 is sent to the notification means 80, and the monitoring result is notified to the user by displaying the monitoring result, for example, on the display 82.
  • the processing unit 100 may monitor the expander motor 42 based on such power consumption at least in the steady operation of the ultra-low temperature refrigerator 10. Similar to the embodiment shown in FIG. 5, the processing unit 100 acquires information indicating the current operation mode of the cryogenic refrigerator 10 from a controller (for example, a compressor controller 24), or measures from a temperature sensor 52. The current operation mode may be determined based on the temperature signal S3. The processing unit 100 may monitor the expander motor 42 based on the power consumption signal S5 when the current operation mode is steady operation. In addition to or instead of this, the processing unit 100 may monitor the expander motor 42 based on the power consumption signal S5 when the current operation mode is the cool-down operation.
  • a controller for example, a compressor controller 24
  • the processing unit 100 may monitor the expander motor 42 based on the power consumption signal S5 when the current operation mode is steady operation.
  • the processing unit 100 may monitor the expander motor 42 based on the power consumption signal S5 when the current operation mode is the cool-down operation.
  • the processing unit 100 may monitor the expander motor 42 based on the power consumption signal S5 indicating the power consumption of the expander motor 42. In this case, the processing unit 100 may acquire the current and voltage supplied to the expander motor 42 and calculate the power consumption of the expander motor 42 from these currents and voltages.
  • the processing unit 100 may acquire the current of the expander motor 42 from the motor current signal S1 input from the current sensor 50.
  • the processing unit 100 may acquire the voltage of the expander motor 42 from the output voltage signal S4 input from the inverter 90.
  • a voltage sensor for measuring the voltage supplied to the expander motor 42 may be provided, and the processing unit 100 may acquire the voltage of the expander motor 42 from the motor voltage signal input from the voltage sensor. good.
  • the processing unit 100 may compare the power consumption of the expander motor 42 with the acquired power consumption threshold Th2 based on the power consumption signal S5, and generate monitoring result data D1 based on the comparison result.
  • FIG. 10 is a flowchart showing a monitoring method of the ultra-low temperature refrigerator 10 according to another embodiment.
  • the power consumption of the inverter 90 or the expander motor 42
  • S30 the power consumption of the inverter 90
  • S40 the expander motor 42 is monitored based on the acquired power consumption
  • the power consumption threshold value Th2 is acquired based on the operating conditions of the expander motor 42 (for example, output frequency information S2, output voltage signal S4, etc.) (S41).
  • the acquired power consumption value of the inverter 90 is compared with the power consumption threshold value Th2 (S42).
  • the comparison unit 70 determines that the occurrence of abnormal operation of the expander motor 42 is predicted (S43), and a monitoring result indicating that fact.
  • the data D1 is output.
  • the comparison unit 70 determines that the occurrence of abnormal operation of the expander motor 42 is not predicted (S44), and the monitoring result data D1 indicating this is determined. Is output. In this way, this monitoring method is completed.
  • the controller of the ultra-low temperature refrigerator 10 lowers the operating frequency of the expander motor 42, for example, issuing a warning.
  • the operation of the ultra-low temperature refrigerator 10 may be stopped, or other measures may be taken to prevent the occurrence of abnormal operation.
  • the processing unit 100 obtains an operating frequency / current threshold table 62 and an external magnetic field / current threshold table in order to acquire a current threshold based on the operating conditions of the expander motor 42. 64, and three current threshold tables of the input voltage / current threshold table 66 are provided. However, these three tables are not essential.
  • the processing unit 100 may include only the operating frequency / current threshold table 62.
  • the processing unit 100 does not have to include the operating frequency / current threshold table 62.
  • the processing unit 100 may include an external magnetic field / current threshold table 64, an input voltage / current threshold table 66, or both, and the external magnetic field / current threshold table 64 (or an input).
  • the voltage / current threshold table 66) may be preset to be used at a specific operating frequency for monitoring.
  • the processing unit 100 may determine whether or not the expander motor 42 is operating at a specific operating frequency for monitoring based on the output frequency information S2, and at this specific operating frequency.
  • the inflator motor 42 may be monitored by comparing the current of the inflator motor 42 with the current threshold value based on the motor current signal S1 obtained during the operation of.
  • the processing unit 100 operates the inverter 90 to drive the expander motor 42 at the monitoring operating frequency, and expands based on the motor current signal S1 when the expander motor 42 is driven at the monitoring operating frequency. It may be configured to monitor the expander motor 42 by comparing the current of the machine motor 42 with the current threshold. In this way, a fixed current threshold value corresponding to the operating frequency for monitoring can be used for comparing the current and the current threshold value of the expander motor 42. Even in this case, the current threshold value may be adjusted based on the motor operating conditions such as an external magnetic field.
  • the cryogenic refrigerator 10 may be a single-stage GM refrigerator or another type of cryogenic freezer comprising an expander motor 42 for operating the expander 14. It may be a machine.
  • the processing unit 100 does not constitute a part of the ultra-low temperature refrigerator 10, but is one of the ultra-low temperature systems (for example, a superconducting device or an MRI system) equipped with the ultra-low temperature refrigerator 10. It may be a department.
  • the ultra-low temperature systems for example, a superconducting device or an MRI system
  • the present invention can be used in the field of an ultra-low temperature freezer and a monitoring method for an ultra-low temperature refrigerator.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
PCT/JP2021/032255 2020-09-25 2021-09-02 極低温冷凍機、および極低温冷凍機の監視方法 Ceased WO2022064989A1 (ja)

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JP2022551230A JP7796659B2 (ja) 2020-09-25 2021-09-02 極低温冷凍機、および極低温冷凍機の監視方法
EP21872120.7A EP4220037A4 (en) 2020-09-25 2021-09-02 ULTRA LOW TEMPERATURE FREEZER AND MONITORING METHOD FOR ULTRA LOW TEMPERATURE FREEZER
CN202180063640.5A CN116324310A (zh) 2020-09-25 2021-09-02 超低温制冷机及超低温制冷机的监控方法
US18/123,347 US20230228472A1 (en) 2020-09-25 2023-03-20 Cryocooler and monitoring method for cryocooler
JP2025278909A JP2026042088A (ja) 2020-09-25 2025-12-23 極低温冷凍機、および極低温冷凍機の監視方法

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CN116710716B (zh) * 2020-12-24 2025-10-21 莱宝德累斯顿有限責任公司 低温制冷系统和低温泵

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EP4220037A4 (en) 2024-03-27
JPWO2022064989A1 (https=) 2022-03-31
JP2026042088A (ja) 2026-03-10
US20230228472A1 (en) 2023-07-20
CN116324310A (zh) 2023-06-23
JP7796659B2 (ja) 2026-01-09

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