WO2023218865A1 - Oil lubrication-type compressor for cryocooler - Google Patents

Oil lubrication-type compressor for cryocooler Download PDF

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Publication number
WO2023218865A1
WO2023218865A1 PCT/JP2023/015355 JP2023015355W WO2023218865A1 WO 2023218865 A1 WO2023218865 A1 WO 2023218865A1 JP 2023015355 W JP2023015355 W JP 2023015355W WO 2023218865 A1 WO2023218865 A1 WO 2023218865A1
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Prior art keywords
oil
heat exchanger
cooled heat
compressor
air
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PCT/JP2023/015355
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French (fr)
Japanese (ja)
Inventor
翔 鈴木
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住友重機械工業株式会社
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Publication of WO2023218865A1 publication Critical patent/WO2023218865A1/en

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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
    • 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

Definitions

  • the present invention relates to an oil-lubricated compressor for a cryogenic refrigerator.
  • An oil-lubricated helium compressor with dual aftercoolers has been proposed (see, for example, Patent Document 1).
  • This compressor has two built-in aftercoolers for cooling helium and oil: a water-cooled aftercooler and an air-cooled aftercooler.
  • the air-cooled aftercooler is arranged in series or parallel with the water-cooled aftercooler. Activating the air-cooled aftercooler's fan provides redundancy in the event that the water-cooled aftercooler's cooling water circuit is blocked.
  • the present inventor studied the above-mentioned helium compressor and recognized the following problems. Since this compressor is equipped with two heat exchangers, one water-cooled and one air-cooled, the total length of the oil line to be cooled tends to be long, which can increase pressure loss in the oil flow. . The resulting decrease in oil flow rate can reduce cooling capacity, which can lead to compressor overheating and shortened service life due to high-temperature operation. In particular, if the temperature of the cooling water supplied to the water-cooled heat exchanger is too low, this problem is likely to occur because the oil viscosity may increase nonlinearly at such a low temperature. A possible measure is to restore the oil flow rate by increasing input energy, for example by driving the oil pump with high power. However, this undesirably increases power consumption.
  • One exemplary objective of an embodiment of the present invention is to reduce pressure loss in an oil line in an oil-lubricated compressor for a cryogenic refrigerator.
  • an oil-lubricated compressor for a cryogenic refrigerator includes an air-cooled heat exchanger including a cooling fan, a first oil line arranged to be forcibly cooled by the cooling fan, and a second oil line that bypasses the first oil line. , is provided.
  • pressure loss in an oil line in an oil-lubricated compressor for a cryogenic refrigerator can be reduced.
  • FIG. 1 is a diagram schematically showing a cryogenic refrigerator according to an embodiment.
  • FIG. 2 is a diagram schematically showing an example of an oil circulation line of a compressor according to an embodiment. It is a figure which shows roughly another example of the oil circulation line of the compressor based on embodiment.
  • FIG. 1 is a diagram schematically showing a cryogenic refrigerator according to an embodiment.
  • the cryogenic refrigerator 10 includes an oil-lubricated cryogenic refrigerator compressor (hereinafter also simply referred to as a compressor) 12 and a cold head 14.
  • the compressor 12 is configured to collect refrigerant gas from the cryogenic refrigerator 10 from the cold head 14, pressurize the collected refrigerant gas, and supply the refrigerant gas to the cold head 14 again.
  • Compressor 12 is also referred to as a compressor unit.
  • the cold head 14 is also called an expander, and has a room temperature section 14a and a low temperature section 14b, also called a cooling stage.
  • the compressor 12 and the cold head 14 constitute a refrigeration cycle of the cryogenic refrigerator 10, whereby the low temperature section 14b is cooled to a desired cryogenic temperature.
  • the refrigerant gas also referred to as the working gas, is typically helium gas, although other suitable gases may be used.
  • the cryogenic refrigerator 10 is, by way of example, a single-stage or two-stage Gifford-McMahon (GM) refrigerator, but may also be a pulse tube refrigerator, a Stirling refrigerator, or other types of cryogenic refrigerators. It may also be a refrigerator. Although the cold head 14 has different configurations depending on the type of cryogenic refrigerator 10, the compressor 12 can have the configuration described below regardless of the type of cryogenic refrigerator 10.
  • GM Gifford-McMahon
  • the pressure of the refrigerant gas supplied from the compressor 12 to the cold head 14 and the pressure of the refrigerant gas recovered from the cold head 14 to the compressor 12 are both significantly higher than atmospheric pressure, and are respectively at the first high pressure and It can be called the second high pressure.
  • the first high pressure and the second high pressure are also simply referred to as high pressure and low pressure, 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 compressor 12 includes a compressor main body 16, a refrigerant gas line 18, an oil circulation line 20, and a compressor cooling system 22.
  • the refrigerant gas line 18 is shown as a solid line
  • the oil circulation line 20 is shown as a broken line.
  • the compressor cooling system 22 includes a liquid-cooled heat exchanger 24 and an air-cooled heat exchanger 26, and is configured to cool the refrigerant gas line 18 and the oil circulation line 20.
  • the compressor 12 also includes a compressor housing 28 that accommodates each component of the compressor 12, such as the compressor main body 16, refrigerant gas line 18, oil circulation line 20, and compressor cooling system 22.
  • the compressor main body 16 is configured to internally compress refrigerant gas sucked in from its suction port and discharge it from its discharge port. Oil is used in the compressor body 16 for cooling and lubrication, and the sucked refrigerant gas is directly exposed to this oil within the compressor body 16. Therefore, the refrigerant gas is sent out from the discharge port with some oil mixed therein.
  • the compressor main body 16 may be, for example, a scroll type, rotary type, or other pump that increases the pressure of refrigerant gas.
  • Compressor body 16 may be configured to deliver a fixed, constant flow rate of refrigerant gas.
  • the compressor main body 16 may be configured to vary the flow rate of refrigerant gas to be discharged.
  • the compressor body 16 is sometimes referred to as a compression capsule.
  • the refrigerant gas line 18 includes a discharge port 30, a suction port 31, a discharge passage 32, and a suction passage 33.
  • the discharge port 30 is a refrigerant gas outlet installed in the compressor casing 28 to send out the refrigerant gas pressurized to high pressure by the compressor main body 16 from the compressor 12, and the suction port 31 is a refrigerant gas outlet installed in the compressor housing 28 to send out the refrigerant gas pressurized to high pressure by the compressor main body 16.
  • a refrigerant gas inlet located in the compressor housing 28 for receiving gas into the compressor 12.
  • the discharge flow path 32 and the suction flow path 33 are housed in the compressor housing 28.
  • a discharge port of the compressor body 16 is connected to a discharge port 30 through a discharge passage 32, and a suction port 31 is connected to an inlet of the compressor body 16 through a suction passage 33.
  • the discharge flow path 32 is provided with a liquid-cooled heat exchanger 24 and an air-cooled heat exchanger 26 that constitute the compressor cooling system 22.
  • an oil separator 34 and an adsorber 35 are provided in the discharge flow path 32 downstream of the compressor cooling system 22.
  • the oil separator 34 is provided to separate oil that is mixed into the refrigerant gas by passing through the compressor main body 16 from the refrigerant gas.
  • the adsorber 35 is provided to remove, for example, vaporized oil and other contaminant components remaining in the refrigerant gas from the refrigerant gas by adsorption.
  • the oil separator 34 and the adsorber 35 are connected in series.
  • the oil separator 34 is arranged on the compressor main body 16 side, and the adsorber 35 is arranged on the discharge port 30 side.
  • An oil return line 21 is provided that connects the oil separator 34 to the compressor body 16.
  • the oil collected by the oil separator 34 can be returned to the compressor body 16 through the oil return line 21 .
  • a filter for removing dust contained in the oil separated by the oil separator 34 and an orifice for controlling the amount of oil returned to the compressor body 16 may be provided in the middle of the oil return line 21 .
  • a storage tank 36 is provided in the suction flow path 33.
  • the storage tank 36 is provided as a volume for removing pulsations contained in the low pressure refrigerant gas returning from the cold head 14 to the compressor 12.
  • the refrigerant gas line 18 is provided with a bypass valve 38 that connects the discharge passage 32 to the suction passage 33 so as to bypass the compressor main body 16.
  • the bypass valve 38 branches from the discharge passage 32 between the oil separator 34 and the adsorber 35, and is connected to the suction passage 33 between the compressor main body 16 and the storage tank 36.
  • the bypass valve 38 is provided for controlling the flow rate of refrigerant gas and/or for equalizing the pressures between the discharge passage 32 and the suction passage 33 when the compressor 12 is stopped.
  • the refrigerant gas line 18 of the compressor 12 is connected to the cold head 14.
  • a high pressure port 40 and a low pressure port 41 are provided in the room temperature section 14a of the cold head 14.
  • the high pressure port 40 is connected to the discharge port 30 by a high pressure pipe 42, and the low pressure port 41 is connected to the suction port 31 by a low pressure pipe 43.
  • the oil circulation line 20 connects the oil outlet of the compressor body 16 to the oil inlet via the compressor cooling system 22 (that is, the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26). Therefore, the oil flowing out from the compressor main body 16 can be cooled by the compressor cooling system 22 and can flow into the compressor main body 16 again.
  • the oil circulation line 20 branches into a plurality of (two in this example) oil flow paths in the compressor cooling system 22, as described below. These branched oil flow paths rejoin between the compressor cooling system 22 and the oil inlet of the compressor body 16.
  • the oil circulation line 20 may be provided with an orifice that controls the flow rate of oil flowing inside. Further, the oil circulation line 20 may be provided with a filter that removes dust contained in the oil. Such orifices and filters may be provided, for example, downstream of the oil circulation line 20, ie between the compressor cooling system 22 and the oil inlet of the compressor body 16.
  • the compressor cooling system 22 includes the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26.
  • the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 are connected in series, and the liquid-cooled heat exchanger 24 is provided upstream of the air-cooled heat exchanger 26. Therefore, the oil and high-pressure refrigerant gas heated by the heat of compression generated as the refrigerant gas is compressed in the compressor main body 16 first flows into the liquid-cooled heat exchanger 24 from the compressor main body 16 and is cooled, and then cools. It flows into the air-cooled heat exchanger 26.
  • the liquid-cooled heat exchanger 24 is mounted on the compressor 12 as a main cooling device for the compressor 12, and the air-cooled heat exchanger 26 is mounted on the compressor 12 as a preliminary cooling device for the compressor 12. There is. Therefore, the liquid-cooled heat exchanger 24 always operates while the compressor 12 is operating, and the air-cooled heat exchanger 26 does not operate when the liquid-cooled heat exchanger 24 is operating normally, and if the liquid-cooled heat exchanger 24 is malfunctioning. It may be activated when it is not activated due to reasons such as, or when its cooling capacity is reduced. Therefore, as will be described later, the air-cooled heat exchanger 26 may be configured to turn itself on and off based on the output of a sensor provided in the compressor 12, such as an oil or refrigerant gas temperature sensor.
  • the liquid-cooled heat exchanger 24 includes a first part 24a that cools the refrigerant gas by heat exchange between the refrigerant gas and the coolant, and a second part 24b that cools the oil by heat exchange between the oil and the coolant.
  • the first portion 24a is disposed in the discharge passage 32 between the compressor body 16 and the oil separator 34, more specifically between the discharge port of the compressor body 16 and the air-cooled heat exchanger 26, and is arranged in the discharge passage 32.
  • the refrigerant gas flowing through 32 is cooled.
  • the second portion 24b is disposed in the oil circulation line 20 between the oil outlet of the compressor body 16 and the air-cooled heat exchanger 26, and cools the oil flowing through the oil circulation line 20.
  • Cooling liquid eg, tap water, industrial water, etc.
  • the cooling liquid is supplied to the compressor 12 from the outside, passes through the first portion 24a and the second portion 24b of the liquid-cooled heat exchanger 24, and is discharged to the outside of the compressor 12. In this way, the heat of compression generated in the compressor body 16 is removed out of the compressor 12 along with the cooling fluid.
  • the coolant may be cooled by a coolant circulation device (not shown) such as a known water chiller, and then supplied to the compressor 12 again.
  • the air-cooled heat exchanger 26 includes a cooling fan 50 , a first oil line 46 arranged to be forcibly cooled by the cooling fan 50 , and a first oil line 46 that bypasses the first oil line 46 and is forcibly cooled by the cooling fan 50 .
  • a second oil line 48 is provided.
  • the first oil line 46 and the second oil line 48 are part of the oil circulation line 20 disposed within the air-cooled heat exchanger 26.
  • the second oil line 48 branches from the oil circulation line 20 upstream of the air-cooled heat exchanger 26, that is, between the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26, and branches downstream of the air-cooled heat exchanger 26, that is, between the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26. It joins the first oil line 46 again between the cold heat exchanger 26 and the oil inlet of the compressor main body 16 .
  • the cooling fan 50 is installed in the compressor housing 28 so as to discharge air from the air-cooled heat exchanger 26 to the outside when the cooling fan 50 is operated.
  • Two air intake ports 52 are provided in a portion of the compressor housing 28 that surrounds the air-cooled heat exchanger 26.
  • air is supplied from the outside to the air-cooled heat exchanger 26 through these air intake ports 52. air is taken in.
  • the air flow blown into the air-cooled heat exchanger 26 from one air intake port 52 is used for forced air cooling of the refrigerant gas line 18 and the first oil line 46, and the air flow is blown into the air-cooled heat exchanger 26 from the other air intake port 52.
  • Another blowing air flow is used for forced air cooling of the second oil line 48.
  • these air flows are schematically shown by thick arrows for understanding.
  • the cooling fan 50 may operate based on the oil temperature measured by an oil temperature sensor.
  • the cooling fan 50 may operate based on the refrigerant gas temperature measured by a refrigerant gas temperature sensor.
  • refrigerant gas recovered from the cold head 14 to the compressor 12 flows from the low pressure port 41 to the suction port 31 of the compressor 12 through the low pressure pipe 43.
  • the refrigerant gas passes through the storage tank 36 on the suction flow path 33 and is recovered to the suction port of the compressor body 16.
  • the refrigerant gas is compressed and pressurized by the compressor main body 16.
  • the refrigerant gas sent out from the discharge port of the compressor main body 16 is cooled by the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26, and further passes through the oil separator 34 and the adsorber 35 before exiting the compressor 12 from the discharge port 30.
  • Refrigerant gas is supplied into the cold head 14 via the high pressure pipe 42 and the high pressure port 40.
  • the oil flowing out from the oil outlet of the compressor body 16 flows into the liquid-cooled heat exchanger 24 through the oil circulation line 20, and is cooled by heat exchange between the oil and the cooling liquid in the liquid-cooled heat exchanger 24.
  • the cooled oil flows from the liquid-cooled heat exchanger 24 to the air-cooled heat exchanger 26 .
  • the oil branches into a first oil line 46 and a second oil line 48 and flows within the air-cooled heat exchanger 26 .
  • the cooling fan 50 When the cooling fan 50 is operating, the oil is cooled by air as it flows through the first oil line 46 and the second oil line 48 . Oil exiting the air-cooled heat exchanger 26 is returned to the oil inlet of the compressor body 16 through the oil circulation line 20.
  • the compressor 12 may be provided with various sensors.
  • compressor 12 may include at least one oil temperature sensor (61-63) that measures the temperature of the oil.
  • the first sensor 61 is provided upstream of the liquid-cooled heat exchanger 24 on the oil circulation line 20 and measures the temperature of the oil flowing into the liquid-cooled heat exchanger 24 from the compressor main body 16 .
  • the second sensor 62 is provided downstream of the liquid-cooled heat exchanger 24 on the oil circulation line 20, specifically between the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26, and is configured to provide air-cooled heat exchange from the liquid-cooled heat exchanger 24 to the air-cooled heat exchanger 26.
  • the temperature of the oil flowing into the vessel 26 is measured.
  • the third sensor 63 is provided downstream of the air-cooled heat exchanger 26 on the oil circulation line 20 and measures the temperature of the oil flowing into the compressor body 16 from the air-cooled heat exchanger 26 .
  • the temperature sensor may be a thermistor, for example.
  • the compressor 12 may include at least one refrigerant gas sensor (64 to 66) that measures the temperature of refrigerant gas.
  • the fourth sensor 64 is provided upstream of the liquid-cooled heat exchanger 24 on the discharge flow path 32 of the refrigerant gas line 18 and measures the temperature of the refrigerant gas flowing into the liquid-cooled heat exchanger 24 from the compressor main body 16 .
  • the fifth sensor 65 is provided downstream of the liquid-cooled heat exchanger 24 on the refrigerant gas line 18, specifically between the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26, and is arranged to exchange heat from the liquid-cooled heat exchanger 24 to the air-cooled heat exchanger 26. The temperature of the refrigerant gas flowing into the vessel 26 is measured.
  • the sixth sensor 66 is provided downstream of the air-cooled heat exchanger 26 on the refrigerant gas line 18 and measures the temperature of the refrigerant gas flowing into the oil separator 34 from the air-cooled heat exchanger 26 .
  • the air-cooled heat exchanger 26 may be provided with a fan controller 54 that turns the cooling fan 50 on and off.
  • the fan controller 54 is configured to receive a sensor signal from at least one sensor indicating a measurement result of the sensor, and operate the cooling fan 50 based on the measurement result. Note that FIG. 1 shows, as an example, a case where a sensor signal from the second sensor 62 is input to the fan controller 54.
  • the fan controller 54 is realized as a hardware configuration by elements and circuits such as a computer's CPU and memory, and as a software configuration is realized by a computer program, etc., but in the figure, it is realized by the cooperation of these as appropriate. It is depicted as a functional block. Those skilled in the art will understand that these functional blocks can be implemented in various ways by combining hardware and software.
  • the fan controller 54 may operate the cooling fan 50 based on the oil temperature measured by at least one oil temperature sensor (61-63).
  • the fan controller 54 receives a sensor signal indicating the measured temperature of the oil from the first sensor 61, the second sensor 62, or the third sensor 63, and compares this measured temperature with a temperature threshold.
  • This temperature threshold is set to a value at which oil cooling is evaluated to be insufficient if the oil temperature is higher than this threshold.
  • the oil temperature measured by the oil temperature sensor exceeds the temperature threshold is, for example, if the temperature of the coolant supplied to the liquid-cooled heat exchanger 24 is too high (i.e., the temperature of the chiller that cools the coolant is too high). (defect or breakdown) or a defect in the liquid-cooled heat exchanger 24 itself (clogged or damaged heat exchanger).
  • the fan controller 54 operates the air-cooled heat exchanger 26 when the measured temperature exceeds the temperature threshold. That is, the fan controller 54 starts the air-cooled heat exchanger 26 by switching the cooling fan 50 from off to on. On the other hand, if the measured temperature does not exceed the temperature threshold, the fan controller 54 does not activate the air-cooled heat exchanger 26 (keeps the cooling fan 50 off). In this manner, by operating the air-cooled heat exchanger 26, which is a preliminary cooling device for the compressor 12, it is possible to cope with a malfunction of the liquid-cooled heat exchanger 24, which is the main cooling device for the compressor 12.
  • the fan controller 54 may operate the cooling fan 50 based on the refrigerant gas temperature measured by the refrigerant gas temperature sensor. For example, the fan controller 54 may receive a sensor signal indicating the measured temperature of the refrigerant gas from the fourth sensor 64 or the fifth sensor 65, and may compare the measured temperature with a temperature threshold. Fan controller 54 activates air-cooled heat exchanger 26 when the measured temperature exceeds the temperature threshold, and does not activate air-cooled heat exchanger 26 when the measured temperature does not exceed the temperature threshold. Even in this case, malfunction of the liquid-cooled heat exchanger 24 can be dealt with using the air-cooled heat exchanger 26.
  • cryogenic refrigerator 10 cooling superconducting magnets.
  • a superconducting magnet is cooled by immersing it in a large amount of liquid helium, and the cryogenic refrigerator 10 is used to cool and recondense the liquid helium.
  • the cryocooler 10 is shut down, large amounts of liquid helium can keep the superconducting magnet cool for some time.
  • research and development has been progressing on superconducting magnets that can significantly reduce the amount of liquid helium used.
  • stopping operation of the cryogenic refrigerator 10 tends to directly lead to loss of cooling of the superconducting magnet.
  • the compressor cooling system 22 since the compressor cooling system 22 includes the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26, redundancy in cooling the compressor 12 is ensured. Even if the liquid-cooled heat exchanger 24 malfunctions, the cooling function of the compressor 12 can be supplemented or replaced by the air-cooled heat exchanger 26. Therefore, the risk of excessive temperature rise of the compressor 12 and the resulting shutdown of the cryogenic refrigerator 10 is reduced. Therefore, the cryogenic refrigerator 10 according to the embodiment is useful for improving the operational continuity of a so-called helium-saving type superconducting device.
  • the compressor cooling system 22 is equipped with two heat exchangers, a liquid-cooled type and an air-cooled type (in particular, the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 are connected in series). Therefore, the total length of the oil circulation line 20 to be cooled tends to be long, which may increase the pressure loss of the oil flow. The resulting decrease in the oil flow rate in the oil circulation line 20 may reduce the cooling capacity of the compressor cooling system 22, which may lead to overheating of the compressor 12 and shortening of its life due to high temperature operation. In particular, if the temperature of the coolant supplied to the liquid-cooled heat exchanger 24 is too low, this problem is likely to occur because the oil viscosity may increase nonlinearly at such a low temperature. A possible measure is to restore the oil flow rate in the oil circulation line 20 by increasing the input energy, for example by driving the oil pump with high power. However, this undesirably increases power consumption.
  • the air-cooled heat exchanger 26 does not have only the first oil line 46, but further includes a second oil line 48 that bypasses the first oil line 46.
  • the passage cross-sectional area of the oil circulation line 20 increases and pressure loss can be reduced. Even if the oil is cooled to a low temperature in the liquid-cooled heat exchanger 24 and the viscosity of the oil discharged from the liquid-cooled heat exchanger 24 increases, a decrease in the oil flow rate flowing through the air-cooled heat exchanger 26 can be suppressed. Insufficient flow of oil circulating through the oil circulation line 20 can be prevented, and insufficient cooling of the compressor 12 can be avoided.
  • FIG. 2 is a diagram schematically showing an example of the oil circulation line 20 of the compressor 12 according to the embodiment.
  • the compressor 12 includes a compressor main body 16, a compressor cooling system 22, and an oil circulation line 20 connecting these.
  • the compressor cooling system 22 includes a liquid-cooled heat exchanger 24 and an air-cooled heat exchanger 26, and is configured to cool the oil circulation line 20.
  • the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 are connected in series, and the liquid-cooled heat exchanger 24 is provided upstream of the air-cooled heat exchanger 26.
  • the oil circulation line 20 branches into a first oil line 46 and a second oil line 48 upstream of the air-cooled heat exchanger 26, that is, between the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26.
  • the air-cooled heat exchanger 26 includes a cooling fan 50, and the first oil line 46 and the second oil line 48 are forcibly cooled by the air flow generated within the air-cooled heat exchanger 26 when the cooling fan 50 operates.
  • the first oil line 46 and the second oil line 48 join together again downstream of the air-cooled heat exchanger 26, that is, between the air-cooled heat exchanger 26 and the oil inlet of the compressor body 16.
  • the air-cooled heat exchanger 26 is provided in at least one of the first oil line 46 and the second oil line 48 so as to reduce the difference between the oil flow rate in the first oil line 46 and the oil flow rate in the second oil line 48.
  • An orifice 56 may also be provided.
  • the oil flow rate in the second oil line 48 is larger than that in the first oil line 46 when the orifice 56 is not present. Therefore, by providing the orifice 56 in the second oil line 48, the oil flow rate in the second oil line 48 can be reduced and the oil flow rates in the first oil line 46 and the second oil line 48 can be equalized. It is possible to eliminate the imbalance in oil flow rates between the first oil line 46 and the second oil line 48, and improve the heat exchange efficiency of the air-cooled heat exchanger 26.
  • the hole diameter R [m] of the orifice 56 may be selected from the range of 1.0 ⁇ 10 ⁇ 4 (m) ⁇ R ⁇ 5.0 ⁇ 10 ⁇ 2 (m).
  • the pore diameter R can be calculated using the following formula.
  • ⁇ is the viscosity [Pa ⁇ s] of the oil flowing into the air-cooled heat exchanger
  • L 1 and L 2 are the lengths of the first oil line 46 and the second oil line 48 as the air-cooled heat exchanger, respectively.
  • [m] and d represent the pipe diameters [m] of the first oil line 46 and the second oil line 48
  • Q represents the oil flow rate [m 3 /s] of the oil circulation line 20.
  • FIG. 3 is a diagram schematically showing another example of the oil circulation line 20 of the compressor 12 according to the embodiment.
  • the compressor 12 includes a compressor main body 16, a compressor cooling system 22, and an oil circulation line 20 connecting these.
  • the compressor cooling system 22 includes a liquid-cooled heat exchanger 24 and an air-cooled heat exchanger 26, and is configured to cool the oil circulation line 20.
  • the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 are connected in series, and the liquid-cooled heat exchanger 24 is provided upstream of the air-cooled heat exchanger 26.
  • the oil circulation line 20 branches into a first oil line 46 and a second oil line 48 upstream of the air-cooled heat exchanger 26, that is, between the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26.
  • the air-cooled heat exchanger 26 includes a cooling fan 50, and the first oil line 46 is forcibly cooled by the air flow generated within the air-cooled heat exchanger 26 when the cooling fan 50 operates.
  • the first oil line 46 and the second oil line 48 join together again downstream of the air-cooled heat exchanger 26, that is, between the air-cooled heat exchanger 26 and the oil inlet of the compressor body 16.
  • the second oil line 48 bypasses the air-cooled heat exchanger 26.
  • the second oil line 48 is provided outside the air-cooled heat exchanger 26 in the compressor 12 and does not pass through the air-cooled heat exchanger 26 .
  • the second oil line 48 may include an on-off valve 58 that closes when the cooling fan 50 is activated and opens when the cooling fan 50 is stopped. Therefore, the fan controller 54 may be configured to receive a sensor signal indicating a measurement result from at least one sensor, and operate the cooling fan 50 and the on-off valve 58 based on the measurement result. The fan controller 54 may operate the cooling fan 50 and close the on-off valve 58, or may stop the cooling fan 50 and open the on-off valve 58. Note that FIG. 3 shows, as an example, a case where a sensor signal from the second sensor 62 is input to the fan controller 54. As mentioned above, other sensors (eg, first sensor 61, or third sensor 63, or fourth sensor 64, or fifth sensor 65) may be used.
  • the on-off valve 58 is closed and the air-cooled heat exchanger 26 is operated to compensate for the cooling failure of the liquid-cooled heat exchanger 24 with the air-cooled heat exchanger 26. Can be replaced.
  • a plurality of oil lines may be provided in the air-cooled heat exchanger 26, and these oil lines may be cooled by the cooling fan 50, similarly to the examples of FIGS. 1 and 2.
  • the oil circulation line 20 branches into a first oil line 46 and a second oil line 48 at the air-cooled heat exchanger 26, but there are more oil lines, for example three or four. You may branch to
  • the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 are connected in series in the compressor cooling system 22, and the liquid-cooled heat exchanger 24 is provided upstream of the air-cooled heat exchanger 26.
  • the compressor cooling system 22 may have other configurations.
  • the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 may be connected in series, and the air-cooled heat exchanger 26 may be provided upstream of the liquid-cooled heat exchanger 24.
  • the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 may be connected in parallel.
  • the cooling fan 50 of the air-cooled heat exchanger 26 may generate an air flow in the opposite direction from the example described above, and may be configured to blow air into the air-cooled heat exchanger 26 from the outside. .
  • the cooling fan 50 may be configured to blow air onto the refrigerant gas line 18, the first oil line 46, and the second oil line 48.
  • the present invention can be used in the field of oil-lubricated compressors for cryogenic refrigerators.

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Abstract

A compressor (12) for a cryocooler (10) is provided with: an air-cooled heat exchanger (26) provided with a cooling fan (50) and a first oil line (46) disposed so as to be forced-cooled by the cooling fan (50); and a second oil line (48) for bypassing the first oil line (46). The second oil line (48) may be disposed so as to be forced-cooled by the cooling fan (50).

Description

オイル潤滑式の極低温冷凍機用圧縮機Oil-lubricated compressor for cryogenic refrigerators
　本発明は、オイル潤滑式の極低温冷凍機用圧縮機に関する。 The present invention relates to an oil-lubricated compressor for a cryogenic refrigerator.
　デュアル・アフタークーラー付きのオイル潤滑ヘリウム圧縮機が提案されている（例えば、特許文献１参照。）。この圧縮機には、ヘリウムおよびオイルを冷却する２つのアフタークーラー、すなわち水冷式アフタークーラーと空冷式アフタークーラーが内蔵される。空冷式アフタークーラーは、水冷式アフタークーラーと直列または並列に配置される。空冷式アフタークーラーのファンを作動させることにより、水冷式アフタークーラーの冷却水回路がブロックされた場合における冗長性が提供される。 An oil-lubricated helium compressor with dual aftercoolers has been proposed (see, for example, Patent Document 1). This compressor has two built-in aftercoolers for cooling helium and oil: a water-cooled aftercooler and an air-cooled aftercooler. The air-cooled aftercooler is arranged in series or parallel with the water-cooled aftercooler. Activating the air-cooled aftercooler's fan provides redundancy in the event that the water-cooled aftercooler's cooling water circuit is blocked.
特開２０１９－５０５７５１号公報Japanese Patent Application Publication No. 2019-505751
　本発明者は、上述のヘリウム圧縮機について検討し、以下の課題を認識した。この圧縮機は水冷式と空冷式の２つの熱交換器を搭載しているため、冷却されるオイルラインの全長が長くなりがちであり、これに起因してオイル流れの圧力損失が増加しうる。その結果生じうるオイル流量低下は、冷却能力を低下させ、ひいては圧縮機のオーバーヒートや高温運転による寿命の低下を招きうる。とくに、水冷式熱交換器に供給される冷却水の温度が低すぎる場合には、そのような低温でオイル粘度が非線形に増加しうることから、この問題が顕在化しやすい。とりうる方策として、例えば、オイルポンプをハイパワーで駆動する等、投入エネルギーを増加することによって、オイル流量を回復させることが考えられる。しかし、これは望ましくないことに、消費電力を増加させることになる。 The present inventor studied the above-mentioned helium compressor and recognized the following problems. Since this compressor is equipped with two heat exchangers, one water-cooled and one air-cooled, the total length of the oil line to be cooled tends to be long, which can increase pressure loss in the oil flow. . The resulting decrease in oil flow rate can reduce cooling capacity, which can lead to compressor overheating and shortened service life due to high-temperature operation. In particular, if the temperature of the cooling water supplied to the water-cooled heat exchanger is too low, this problem is likely to occur because the oil viscosity may increase nonlinearly at such a low temperature. A possible measure is to restore the oil flow rate by increasing input energy, for example by driving the oil pump with high power. However, this undesirably increases power consumption.
　本発明のある態様の例示的な目的のひとつは、オイル潤滑式の極低温冷凍機用圧縮機におけるオイルラインの圧力損失を低減することにある。 One exemplary objective of an embodiment of the present invention is to reduce pressure loss in an oil line in an oil-lubricated compressor for a cryogenic refrigerator.
　本発明のある態様によると、オイル潤滑式の極低温冷凍機用圧縮機が提供される。極低温冷凍機用圧縮機は、冷却ファンと、冷却ファンによって強制冷却されるように配置された第１オイルラインとを備える空冷熱交換器と、第１オイルラインをバイパスする第２オイルラインと、を備える。 According to one aspect of the present invention, an oil-lubricated compressor for a cryogenic refrigerator is provided. A compressor for a cryogenic refrigerator includes an air-cooled heat exchanger including a cooling fan, a first oil line arranged to be forcibly cooled by the cooling fan, and a second oil line that bypasses the first oil line. , is provided.
　本発明によれば、オイル潤滑式の極低温冷凍機用圧縮機におけるオイルラインの圧力損失を低減することができる。 According to the present invention, pressure loss in an oil line in an oil-lubricated compressor for a cryogenic refrigerator can be reduced.
実施の形態に係る極低温冷凍機を概略的に示す図である。FIG. 1 is a diagram schematically showing a cryogenic refrigerator according to an embodiment. 実施の形態に係る圧縮機のオイル循環ラインの一例を概略的に示す図である。FIG. 2 is a diagram schematically showing an example of an oil circulation line of a compressor according to an embodiment. 実施の形態に係る圧縮機のオイル循環ラインの他の一例を概略的に示す図である。It is a figure which shows roughly another example of the oil circulation line of the compressor based on embodiment.
　以下、図面を参照しながら、本発明を実施するための形態について詳細に説明する。説明および図面において同一または同等の構成要素、部材、処理には同一の符号を付し、重複する説明は適宜省略する。図示される各部の縮尺や形状は、説明を容易にするために便宜的に設定されており、特に言及がない限り限定的に解釈されるものではない。実施の形態は例示であり、本発明の範囲を何ら限定するものではない。実施の形態に記述されるすべての特徴やその組み合わせは、必ずしも発明の本質的なものであるとは限らない。 Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description and drawings, the same or equivalent components, members, and processes are denoted by the same reference numerals, and overlapping explanations will be omitted as appropriate. The scales and shapes of the parts shown in the figures are set for convenience to facilitate explanation, and should not be interpreted in a limited manner unless otherwise stated. The embodiments are illustrative and do not limit the scope of the present invention. All features and combinations thereof described in the embodiments are not necessarily essential to the invention.
　図１は、実施の形態に係る極低温冷凍機を概略的に示す図である。 FIG. 1 is a diagram schematically showing a cryogenic refrigerator according to an embodiment.
　極低温冷凍機１０は、オイル潤滑式の極低温冷凍機用圧縮機（以下、単に圧縮機ともいう）１２と、コールドヘッド１４とを備える。圧縮機１２は、極低温冷凍機１０の冷媒ガスをコールドヘッド１４から回収し、回収した冷媒ガスを昇圧して、再び冷媒ガスをコールドヘッド１４に供給するよう構成されている。圧縮機１２は、圧縮機ユニットとも称される。コールドヘッド１４は、膨張機とも称され、室温部１４ａと、冷却ステージとも称される低温部１４ｂとを有する。圧縮機１２とコールドヘッド１４により極低温冷凍機１０の冷凍サイクルが構成され、それにより低温部１４ｂが所望の極低温に冷却される。冷媒ガスは、作動ガスとも称され、通例はヘリウムガスであるが、適切な他のガスが用いられてもよい。 The cryogenic refrigerator 10 includes an oil-lubricated cryogenic refrigerator compressor (hereinafter also simply referred to as a compressor) 12 and a cold head 14. The compressor 12 is configured to collect refrigerant gas from the cryogenic refrigerator 10 from the cold head 14, pressurize the collected refrigerant gas, and supply the refrigerant gas to the cold head 14 again. Compressor 12 is also referred to as a compressor unit. The cold head 14 is also called an expander, and has a room temperature section 14a and a low temperature section 14b, also called a cooling stage. The compressor 12 and the cold head 14 constitute a refrigeration cycle of the cryogenic refrigerator 10, whereby the low temperature section 14b is cooled to a desired cryogenic temperature. The refrigerant gas, also referred to as the working gas, is typically helium gas, although other suitable gases may be used.
　極低温冷凍機１０は、一例として、単段式または二段式のギフォード・マクマホン（Gifford-McMahon；ＧＭ）冷凍機であるが、パルス管冷凍機、スターリング冷凍機、またはそのほかのタイプの極低温冷凍機であってもよい。コールドヘッド１４は、極低温冷凍機１０のタイプに応じて異なる構成を有するが、圧縮機１２は、極低温冷凍機１０のタイプによらず、以下に説明する構成を用いることができる。 The cryogenic refrigerator 10 is, by way of example, a single-stage or two-stage Gifford-McMahon (GM) refrigerator, but may also be a pulse tube refrigerator, a Stirling refrigerator, or other types of cryogenic refrigerators. It may also be a refrigerator. Although the cold head 14 has different configurations depending on the type of cryogenic refrigerator 10, the compressor 12 can have the configuration described below regardless of the type of cryogenic refrigerator 10.
　なお、一般に、圧縮機１２からコールドヘッド１４に供給される冷媒ガスの圧力と、コールドヘッド１４から圧縮機１２に回収される冷媒ガスの圧力は、ともに大気圧よりかなり高く、それぞれ第１高圧及び第２高圧と呼ぶことができる。説明の便宜上、第１高圧及び第２高圧はそれぞれ単に高圧及び低圧とも呼ばれる。典型的には、高圧は例えば２～３ＭＰａである。低圧は例えば０．５～１．５ＭＰａであり、例えば約０．８ＭＰａである。 Generally, the pressure of the refrigerant gas supplied from the compressor 12 to the cold head 14 and the pressure of the refrigerant gas recovered from the cold head 14 to the compressor 12 are both significantly higher than atmospheric pressure, and are respectively at the first high pressure and It can be called the second high pressure. For convenience of explanation, the first high pressure and the second high pressure are also simply referred to as high pressure and low pressure, respectively. Typically, 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.
　圧縮機１２は、圧縮機本体１６、冷媒ガスライン１８、オイル循環ライン２０、圧縮機冷却系２２を備える。図１では、理解を容易にするために、冷媒ガスライン１８を実線で示し、オイル循環ライン２０を破線で示している。詳細は後述するが、圧縮機冷却系２２は、液冷熱交換器２４および空冷熱交換器２６を備え、冷媒ガスライン１８およびオイル循環ライン２０を冷却するように構成されている。また、圧縮機１２は、圧縮機本体１６、冷媒ガスライン１８、オイル循環ライン２０、圧縮機冷却系２２など、圧縮機１２の各構成要素を収容する圧縮機筐体２８を備える。 The compressor 12 includes a compressor main body 16, a refrigerant gas line 18, an oil circulation line 20, and a compressor cooling system 22. In FIG. 1, for ease of understanding, the refrigerant gas line 18 is shown as a solid line, and the oil circulation line 20 is shown as a broken line. Although details will be described later, the compressor cooling system 22 includes a liquid-cooled heat exchanger 24 and an air-cooled heat exchanger 26, and is configured to cool the refrigerant gas line 18 and the oil circulation line 20. The compressor 12 also includes a compressor housing 28 that accommodates each component of the compressor 12, such as the compressor main body 16, refrigerant gas line 18, oil circulation line 20, and compressor cooling system 22.
　圧縮機本体１６は、その吸入口から吸入される冷媒ガスを内部で圧縮して吐出口から吐出するよう構成されている。圧縮機本体１６では冷却と潤滑のためにオイルが使用され、吸入された冷媒ガスは圧縮機本体１６内でこのオイルに直接さらされる。よって、冷媒ガスは、オイルが若干混入した状態で吐出口から送出される。 The compressor main body 16 is configured to internally compress refrigerant gas sucked in from its suction port and discharge it from its discharge port. Oil is used in the compressor body 16 for cooling and lubrication, and the sucked refrigerant gas is directly exposed to this oil within the compressor body 16. Therefore, the refrigerant gas is sent out from the discharge port with some oil mixed therein.
　圧縮機本体１６は、例えば、スクロール方式、ロータリ式、または冷媒ガスを昇圧するそのほかのポンプであってもよい。圧縮機本体１６は、固定された一定の冷媒ガス流量を吐出するよう構成されていてもよい。あるいは、圧縮機本体１６は、吐出する冷媒ガス流量を可変とするよう構成されていてもよい。圧縮機本体１６は、圧縮カプセルと称されることもある。 The compressor main body 16 may be, for example, a scroll type, rotary type, or other pump that increases the pressure of refrigerant gas. Compressor body 16 may be configured to deliver a fixed, constant flow rate of refrigerant gas. Alternatively, the compressor main body 16 may be configured to vary the flow rate of refrigerant gas to be discharged. The compressor body 16 is sometimes referred to as a compression capsule.
　冷媒ガスライン１８は、吐出ポート３０、吸入ポート３１、吐出流路３２、吸入流路３３を備える。吐出ポート３０は、圧縮機本体１６により高圧に昇圧された冷媒ガスを圧縮機１２から送出するために圧縮機筐体２８に設置された冷媒ガスの出口であり、吸入ポート３１は、低圧の冷媒ガスを圧縮機１２に受け入れるために圧縮機筐体２８に設置された冷媒ガスの入口である。吐出流路３２および吸入流路３３は、圧縮機筐体２８に収容されている。圧縮機本体１６の吐出口が吐出流路３２により吐出ポート３０に接続され、吸入ポート３１が吸入流路３３により圧縮機本体１６の吸入口に接続されている。 The refrigerant gas line 18 includes a discharge port 30, a suction port 31, a discharge passage 32, and a suction passage 33. The discharge port 30 is a refrigerant gas outlet installed in the compressor casing 28 to send out the refrigerant gas pressurized to high pressure by the compressor main body 16 from the compressor 12, and the suction port 31 is a refrigerant gas outlet installed in the compressor housing 28 to send out the refrigerant gas pressurized to high pressure by the compressor main body 16. A refrigerant gas inlet located in the compressor housing 28 for receiving gas into the compressor 12. The discharge flow path 32 and the suction flow path 33 are housed in the compressor housing 28. A discharge port of the compressor body 16 is connected to a discharge port 30 through a discharge passage 32, and a suction port 31 is connected to an inlet of the compressor body 16 through a suction passage 33.
　吐出流路３２には、圧縮機冷却系２２を構成する液冷熱交換器２４および空冷熱交換器２６が設けられている。加えて、吐出流路３２には、圧縮機冷却系２２の下流にオイルセパレータ３４およびアドゾーバ３５が設けられている。 The discharge flow path 32 is provided with a liquid-cooled heat exchanger 24 and an air-cooled heat exchanger 26 that constitute the compressor cooling system 22. In addition, an oil separator 34 and an adsorber 35 are provided in the discharge flow path 32 downstream of the compressor cooling system 22.
　オイルセパレータ３４は、圧縮機本体１６を通ることによって冷媒ガスに混入するオイルを冷媒ガスから分離するために設けられている。アドゾーバ３５は、冷媒ガスに残留している例えば気化したオイルそのほかの汚染成分を冷媒ガスから吸着により除去するために設けられている。オイルセパレータ３４とアドゾーバ３５は、直列に接続されている。吐出流路３２において、オイルセパレータ３４が圧縮機本体１６側に配置され、アドゾーバ３５が吐出ポート３０側に配置されている。 The oil separator 34 is provided to separate oil that is mixed into the refrigerant gas by passing through the compressor main body 16 from the refrigerant gas. The adsorber 35 is provided to remove, for example, vaporized oil and other contaminant components remaining in the refrigerant gas from the refrigerant gas by adsorption. The oil separator 34 and the adsorber 35 are connected in series. In the discharge flow path 32, the oil separator 34 is arranged on the compressor main body 16 side, and the adsorber 35 is arranged on the discharge port 30 side.
　オイルセパレータ３４を圧縮機本体１６に接続するオイル戻りライン２１が設けられている。オイル戻りライン２１を通じて、オイルセパレータ３４で回収されたオイルを圧縮機本体１６に戻すことができる。オイル戻りライン２１の途中には、オイルセパレータ３４で分離されたオイルに含まれる塵埃を除去するフィルターと、圧縮機本体１６へのオイルの戻り量を制御するオリフィスが設けられてもよい。 An oil return line 21 is provided that connects the oil separator 34 to the compressor body 16. The oil collected by the oil separator 34 can be returned to the compressor body 16 through the oil return line 21 . A filter for removing dust contained in the oil separated by the oil separator 34 and an orifice for controlling the amount of oil returned to the compressor body 16 may be provided in the middle of the oil return line 21 .
　一方、吸入流路３３には、ストレージタンク３６が設けられている。ストレージタンク３６は、コールドヘッド１４から圧縮機１２へと戻る低圧の冷媒ガスに含まれる脈動を除去するための容積として設けられている。 On the other hand, a storage tank 36 is provided in the suction flow path 33. The storage tank 36 is provided as a volume for removing pulsations contained in the low pressure refrigerant gas returning from the cold head 14 to the compressor 12.
　また、冷媒ガスライン１８には、圧縮機本体１６を迂回するように吐出流路３２を吸入流路３３に接続するバイパス弁３８が設けられている。一例として、バイパス弁３８は、オイルセパレータ３４とアドゾーバ３５の間で吐出流路３２から分岐し、圧縮機本体１６とストレージタンク３６の間で吸入流路３３に接続される。バイパス弁３８は、冷媒ガス流量制御のために、及び／または、圧縮機１２を停止する際の吐出流路３２と吸入流路３３との均圧化のために設けられている。 Furthermore, the refrigerant gas line 18 is provided with a bypass valve 38 that connects the discharge passage 32 to the suction passage 33 so as to bypass the compressor main body 16. As an example, the bypass valve 38 branches from the discharge passage 32 between the oil separator 34 and the adsorber 35, and is connected to the suction passage 33 between the compressor main body 16 and the storage tank 36. The bypass valve 38 is provided for controlling the flow rate of refrigerant gas and/or for equalizing the pressures between the discharge passage 32 and the suction passage 33 when the compressor 12 is stopped.
　圧縮機１２の冷媒ガスライン１８は、コールドヘッド１４に接続される。コールドヘッド１４の室温部１４ａには、高圧ポート４０および低圧ポート４１が設けられている。高圧ポート４０は、高圧配管４２によって吐出ポート３０に接続され、低圧ポート４１は、低圧配管４３によって吸入ポート３１に接続されている。 The refrigerant gas line 18 of the compressor 12 is connected to the cold head 14. A high pressure port 40 and a low pressure port 41 are provided in the room temperature section 14a of the cold head 14. The high pressure port 40 is connected to the discharge port 30 by a high pressure pipe 42, and the low pressure port 41 is connected to the suction port 31 by a low pressure pipe 43.
　オイル循環ライン２０は、圧縮機冷却系２２（すなわち液冷熱交換器２４および空冷熱交換器２６）を経由するように、圧縮機本体１６のオイル出口をオイル入口に接続する。よって、圧縮機本体１６から流出するオイルが圧縮機冷却系２２により冷却され再び圧縮機本体１６に流入することができる。 The oil circulation line 20 connects the oil outlet of the compressor body 16 to the oil inlet via the compressor cooling system 22 (that is, the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26). Therefore, the oil flowing out from the compressor main body 16 can be cooled by the compressor cooling system 22 and can flow into the compressor main body 16 again.
　この実施の形態では、オイル循環ライン２０は、後述のように、圧縮機冷却系２２において複数（この例では２つ）のオイル流路に分岐している。これら分岐したオイル流路は、圧縮機冷却系２２と圧縮機本体１６のオイル入口との間で再び合流している。 In this embodiment, the oil circulation line 20 branches into a plurality of (two in this example) oil flow paths in the compressor cooling system 22, as described below. These branched oil flow paths rejoin between the compressor cooling system 22 and the oil inlet of the compressor body 16.
　オイル循環ライン２０には、内部を流れるオイル流量を制御するオリフィスが設けられていてもよい。また、オイル循環ライン２０には、オイルに含まれる塵埃を除去するフィルターが設けられてもよい。こうしたオリフィスとフィルターは、例えば、オイル循環ライン２０の下流側、つまり圧縮機冷却系２２と圧縮機本体１６のオイル入口との間に設けられてもよい。 The oil circulation line 20 may be provided with an orifice that controls the flow rate of oil flowing inside. Further, the oil circulation line 20 may be provided with a filter that removes dust contained in the oil. Such orifices and filters may be provided, for example, downstream of the oil circulation line 20, ie between the compressor cooling system 22 and the oil inlet of the compressor body 16.
　圧縮機冷却系２２は上述のように、液冷熱交換器２４および空冷熱交換器２６を備える。液冷熱交換器２４と空冷熱交換器２６は直列に接続され、液冷熱交換器２４が空冷熱交換器２６の上流に設けられている。よって、圧縮機本体１６での冷媒ガスの圧縮に伴って生じる圧縮熱により加熱されたオイルおよび高圧の冷媒ガスは、圧縮機本体１６から最初に液冷熱交換器２４に流入して冷却され、次に空冷熱交換器２６に流入する。 As mentioned above, the compressor cooling system 22 includes the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26. The liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 are connected in series, and the liquid-cooled heat exchanger 24 is provided upstream of the air-cooled heat exchanger 26. Therefore, the oil and high-pressure refrigerant gas heated by the heat of compression generated as the refrigerant gas is compressed in the compressor main body 16 first flows into the liquid-cooled heat exchanger 24 from the compressor main body 16 and is cooled, and then cools. It flows into the air-cooled heat exchanger 26.
　この実施の形態では、液冷熱交換器２４は、圧縮機１２の主冷却装置として圧縮機１２に搭載され、空冷熱交換器２６は、圧縮機１２の予備冷却装置として圧縮機１２に搭載されている。よって、液冷熱交換器２４は、圧縮機１２の運転中常時作動し、空冷熱交換器２６は、液冷熱交換器２４が正常に作動しているときには作動せず、液冷熱交換器２４が故障等により作動しないときまたはその冷却能力が低下したとき作動してもよい。そこで、後述のように、空冷熱交換器２６は、オイルまたは冷媒ガスの温度センサなど圧縮機１２に設けられたセンサの出力に基づいて自身のオンオフを切り替えるように構成されてもよい。 In this embodiment, the liquid-cooled heat exchanger 24 is mounted on the compressor 12 as a main cooling device for the compressor 12, and the air-cooled heat exchanger 26 is mounted on the compressor 12 as a preliminary cooling device for the compressor 12. There is. Therefore, the liquid-cooled heat exchanger 24 always operates while the compressor 12 is operating, and the air-cooled heat exchanger 26 does not operate when the liquid-cooled heat exchanger 24 is operating normally, and if the liquid-cooled heat exchanger 24 is malfunctioning. It may be activated when it is not activated due to reasons such as, or when its cooling capacity is reduced. Therefore, as will be described later, the air-cooled heat exchanger 26 may be configured to turn itself on and off based on the output of a sensor provided in the compressor 12, such as an oil or refrigerant gas temperature sensor.
　液冷熱交換器２４は、冷媒ガスと冷却液との熱交換により冷媒ガスを冷却する第１部分２４ａと、オイルと冷却液との熱交換によりオイルを冷却する第２部分２４ｂとを備える。第１部分２４ａは、吐出流路３２において圧縮機本体１６とオイルセパレータ３４の間、より具体的には、圧縮機本体１６の吐出口と空冷熱交換器２６の間に配置され、吐出流路３２を流れる冷媒ガスを冷却する。第２部分２４ｂは、オイル循環ライン２０において圧縮機本体１６のオイル出口と空冷熱交換器２６の間に配置され、オイル循環ライン２０を流れるオイルを冷却する。 The liquid-cooled heat exchanger 24 includes a first part 24a that cools the refrigerant gas by heat exchange between the refrigerant gas and the coolant, and a second part 24b that cools the oil by heat exchange between the oil and the coolant. The first portion 24a is disposed in the discharge passage 32 between the compressor body 16 and the oil separator 34, more specifically between the discharge port of the compressor body 16 and the air-cooled heat exchanger 26, and is arranged in the discharge passage 32. The refrigerant gas flowing through 32 is cooled. The second portion 24b is disposed in the oil circulation line 20 between the oil outlet of the compressor body 16 and the air-cooled heat exchanger 26, and cools the oil flowing through the oil circulation line 20.
　冷却液としては典型的に、水（例えば、水道水、工業用水など）が使用されるが、適切な他の冷却液が使用されてもよい。冷却液は、外部から圧縮機１２に供給され、液冷熱交換器２４の第１部分２４ａおよび第２部分２４ｂを経て、圧縮機１２の外部に排出される。このようにして、圧縮機本体１６で生じる圧縮熱は、冷却液とともに圧縮機１２の外へと除去される。なお、冷却液は、例えば公知の水チラーなどの冷却液循環装置（図示せず）により冷却され、再び圧縮機１２に供給されてもよい。 Water (eg, tap water, industrial water, etc.) is typically used as the cooling liquid, although other suitable cooling liquids may be used. The cooling liquid is supplied to the compressor 12 from the outside, passes through the first portion 24a and the second portion 24b of the liquid-cooled heat exchanger 24, and is discharged to the outside of the compressor 12. In this way, the heat of compression generated in the compressor body 16 is removed out of the compressor 12 along with the cooling fluid. Note that the coolant may be cooled by a coolant circulation device (not shown) such as a known water chiller, and then supplied to the compressor 12 again.
　空冷熱交換器２６は、冷却ファン５０と、冷却ファン５０によって強制冷却されるように配置された第１オイルライン４６と、第１オイルライン４６をバイパスし、冷却ファン５０によって強制冷却されるように配置された第２オイルライン４８とを備える。 The air-cooled heat exchanger 26 includes a cooling fan 50 , a first oil line 46 arranged to be forcibly cooled by the cooling fan 50 , and a first oil line 46 that bypasses the first oil line 46 and is forcibly cooled by the cooling fan 50 . A second oil line 48 is provided.
　第１オイルライン４６と第２オイルライン４８は空冷熱交換器２６内に配置されたオイル循環ライン２０の一部分である。第２オイルライン４８は、空冷熱交換器２６の上流、つまり液冷熱交換器２４と空冷熱交換器２６との間で、オイル循環ライン２０から分岐し、空冷熱交換器２６の下流、つまり空冷熱交換器２６と圧縮機本体１６のオイル入口との間で、第１オイルライン４６と再び合流する。 The first oil line 46 and the second oil line 48 are part of the oil circulation line 20 disposed within the air-cooled heat exchanger 26. The second oil line 48 branches from the oil circulation line 20 upstream of the air-cooled heat exchanger 26, that is, between the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26, and branches downstream of the air-cooled heat exchanger 26, that is, between the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26. It joins the first oil line 46 again between the cold heat exchanger 26 and the oil inlet of the compressor main body 16 .
　例示的な構成として、冷却ファン５０は、その作動により、空冷熱交換器２６から外部へと空気を排出するように圧縮機筐体２８に設置されている。圧縮機筐体２８のうち空冷熱交換器２６を囲む部分には、２つの空気取入口５２が設けられており、冷却ファン５０の作動により、外部からこれら空気取入口５２を通じて空冷熱交換器２６に空気が取り込まれる。一方の空気取入口５２から空冷熱交換器２６内に吹き込む空気流れは、冷媒ガスライン１８と第１オイルライン４６の強制空冷に使用され、他方の空気取入口５２から空冷熱交換器２６内に吹き込むもう一つの空気流れは、第２オイルライン４８の強制空冷に使用される。図１では、理解のために、これら空気流れを太い矢印で模式的に示している。 As an exemplary configuration, the cooling fan 50 is installed in the compressor housing 28 so as to discharge air from the air-cooled heat exchanger 26 to the outside when the cooling fan 50 is operated. Two air intake ports 52 are provided in a portion of the compressor housing 28 that surrounds the air-cooled heat exchanger 26. When the cooling fan 50 operates, air is supplied from the outside to the air-cooled heat exchanger 26 through these air intake ports 52. air is taken in. The air flow blown into the air-cooled heat exchanger 26 from one air intake port 52 is used for forced air cooling of the refrigerant gas line 18 and the first oil line 46, and the air flow is blown into the air-cooled heat exchanger 26 from the other air intake port 52. Another blowing air flow is used for forced air cooling of the second oil line 48. In FIG. 1, these air flows are schematically shown by thick arrows for understanding.
　後述のように、冷却ファン５０は、オイル温度センサによって測定されるオイル温度に基づいて作動してもよい。あるいは、冷却ファン５０は、冷媒ガス温度センサによって測定される冷媒ガス温度に基づいて作動してもよい。 As described below, the cooling fan 50 may operate based on the oil temperature measured by an oil temperature sensor. Alternatively, the cooling fan 50 may operate based on the refrigerant gas temperature measured by a refrigerant gas temperature sensor.
　極低温冷凍機１０の運転中、コールドヘッド１４から圧縮機１２に回収される冷媒ガスは、低圧ポート４１から低圧配管４３を通じて圧縮機１２の吸入ポート３１に流入する。冷媒ガスは、吸入流路３３上のストレージタンク３６を経て、圧縮機本体１６の吸入口へと回収される。冷媒ガスは、圧縮機本体１６によって圧縮され昇圧される。圧縮機本体１６の吐出口から送出される冷媒ガスは、液冷熱交換器２４および空冷熱交換器２６で冷却され、さらに、オイルセパレータ３４、アドゾーバ３５を経て、吐出ポート３０から圧縮機１２を出る。冷媒ガスは、高圧配管４２と高圧ポート４０を経てコールドヘッド１４の内部に供給される。 During operation of the cryogenic refrigerator 10, refrigerant gas recovered from the cold head 14 to the compressor 12 flows from the low pressure port 41 to the suction port 31 of the compressor 12 through the low pressure pipe 43. The refrigerant gas passes through the storage tank 36 on the suction flow path 33 and is recovered to the suction port of the compressor body 16. The refrigerant gas is compressed and pressurized by the compressor main body 16. The refrigerant gas sent out from the discharge port of the compressor main body 16 is cooled by the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26, and further passes through the oil separator 34 and the adsorber 35 before exiting the compressor 12 from the discharge port 30. . Refrigerant gas is supplied into the cold head 14 via the high pressure pipe 42 and the high pressure port 40.
　圧縮機本体１６のオイル出口から流出するオイルは、オイル循環ライン２０を通じて液冷熱交換器２４に流入し、液冷熱交換器２４でオイルと冷却液との熱交換により冷却される。冷却されたオイルは液冷熱交換器２４から空冷熱交換器２６に流入する。オイルは、空冷熱交換器２６内で第１オイルライン４６と第２オイルライン４８に分岐して流れる。冷却ファン５０が作動している場合、オイルは第１オイルライン４６と第２オイルライン４８を流れるとき空気で冷却される。空冷熱交換器２６から流出するオイルは、オイル循環ライン２０を通じて圧縮機本体１６のオイル入口へと戻される。 The oil flowing out from the oil outlet of the compressor body 16 flows into the liquid-cooled heat exchanger 24 through the oil circulation line 20, and is cooled by heat exchange between the oil and the cooling liquid in the liquid-cooled heat exchanger 24. The cooled oil flows from the liquid-cooled heat exchanger 24 to the air-cooled heat exchanger 26 . The oil branches into a first oil line 46 and a second oil line 48 and flows within the air-cooled heat exchanger 26 . When the cooling fan 50 is operating, the oil is cooled by air as it flows through the first oil line 46 and the second oil line 48 . Oil exiting the air-cooled heat exchanger 26 is returned to the oil inlet of the compressor body 16 through the oil circulation line 20.
　圧縮機１２には、各種のセンサが設けられていてもよい。たとえば、圧縮機１２は、オイルの温度を測定する少なくとも１つのオイル温度センサ（６１～６３）を備えてもよい。第１センサ６１は、オイル循環ライン２０上で液冷熱交換器２４の上流に設けられ、圧縮機本体１６から液冷熱交換器２４に流入するオイルの温度を測定する。第２センサ６２は、オイル循環ライン２０上で液冷熱交換器２４の下流、具体的には液冷熱交換器２４と空冷熱交換器２６の間に設けられ、液冷熱交換器２４から空冷熱交換器２６に流入するオイルの温度を測定する。第３センサ６３は、オイル循環ライン２０上で空冷熱交換器２６の下流に設けられ、空冷熱交換器２６から圧縮機本体１６に流入するオイルの温度を測定する。温度センサは、例えばサーミスタであってもよい。 The compressor 12 may be provided with various sensors. For example, compressor 12 may include at least one oil temperature sensor (61-63) that measures the temperature of the oil. The first sensor 61 is provided upstream of the liquid-cooled heat exchanger 24 on the oil circulation line 20 and measures the temperature of the oil flowing into the liquid-cooled heat exchanger 24 from the compressor main body 16 . The second sensor 62 is provided downstream of the liquid-cooled heat exchanger 24 on the oil circulation line 20, specifically between the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26, and is configured to provide air-cooled heat exchange from the liquid-cooled heat exchanger 24 to the air-cooled heat exchanger 26. The temperature of the oil flowing into the vessel 26 is measured. The third sensor 63 is provided downstream of the air-cooled heat exchanger 26 on the oil circulation line 20 and measures the temperature of the oil flowing into the compressor body 16 from the air-cooled heat exchanger 26 . The temperature sensor may be a thermistor, for example.
　圧縮機１２は、冷媒ガスの温度を測定する少なくとも１つの冷媒ガスセンサ（６４～６６）を備えてもよい。第４センサ６４は、冷媒ガスライン１８の吐出流路３２上で液冷熱交換器２４の上流に設けられ、圧縮機本体１６から液冷熱交換器２４に流入する冷媒ガスの温度を測定する。第５センサ６５は、冷媒ガスライン１８上で液冷熱交換器２４の下流、具体的には液冷熱交換器２４と空冷熱交換器２６の間に設けられ、液冷熱交換器２４から空冷熱交換器２６に流入する冷媒ガスの温度を測定する。第６センサ６６は、冷媒ガスライン１８上で空冷熱交換器２６の下流に設けられ、空冷熱交換器２６からオイルセパレータ３４に流入する冷媒ガスの温度を測定する。 The compressor 12 may include at least one refrigerant gas sensor (64 to 66) that measures the temperature of refrigerant gas. The fourth sensor 64 is provided upstream of the liquid-cooled heat exchanger 24 on the discharge flow path 32 of the refrigerant gas line 18 and measures the temperature of the refrigerant gas flowing into the liquid-cooled heat exchanger 24 from the compressor main body 16 . The fifth sensor 65 is provided downstream of the liquid-cooled heat exchanger 24 on the refrigerant gas line 18, specifically between the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26, and is arranged to exchange heat from the liquid-cooled heat exchanger 24 to the air-cooled heat exchanger 26. The temperature of the refrigerant gas flowing into the vessel 26 is measured. The sixth sensor 66 is provided downstream of the air-cooled heat exchanger 26 on the refrigerant gas line 18 and measures the temperature of the refrigerant gas flowing into the oil separator 34 from the air-cooled heat exchanger 26 .
　空冷熱交換器２６には、冷却ファン５０をオンオフするファンコントローラ５４が設けられていてもよい。ファンコントローラ５４は、少なくとも１つのセンサから当該センサの測定結果を示すセンサ信号を受け、測定結果に基づいて冷却ファン５０を作動させるように構成される。なお図１には、例として、第２センサ６２のセンサ信号がファンコントローラ５４に入力される場合を示している。 The air-cooled heat exchanger 26 may be provided with a fan controller 54 that turns the cooling fan 50 on and off. The fan controller 54 is configured to receive a sensor signal from at least one sensor indicating a measurement result of the sensor, and operate the cooling fan 50 based on the measurement result. Note that FIG. 1 shows, as an example, a case where a sensor signal from the second sensor 62 is input to the fan controller 54.
　ファンコントローラ５４は、ハードウェア構成としてはコンピュータのＣＰＵやメモリをはじめとする素子や回路で実現され、ソフトウェア構成としてはコンピュータプログラム等によって実現されるが、図では適宜、それらの連携によって実現される機能ブロックとして描いている。これらの機能ブロックはハードウェア、ソフトウェアの組合せによっていろいろなかたちで実現できることは、当業者には理解されるところである。 The fan controller 54 is realized as a hardware configuration by elements and circuits such as a computer's CPU and memory, and as a software configuration is realized by a computer program, etc., but in the figure, it is realized by the cooperation of these as appropriate. It is depicted as a functional block. Those skilled in the art will understand that these functional blocks can be implemented in various ways by combining hardware and software.
　例えば、ファンコントローラ５４は、少なくとも１つのオイル温度センサ（６１～６３）によって測定されるオイル温度に基づいて、冷却ファン５０を作動させてもよい。この場合、ファンコントローラ５４は、オイルの測定温度を示すセンサ信号を第１センサ６１、または第２センサ６２、または第３センサ６３から受け、この測定温度を温度しきい値と比較する。この温度しきい値は、オイル温度がこのしきい値よりも高い場合、オイルの冷却が不十分であると評価される値に設定される。 For example, the fan controller 54 may operate the cooling fan 50 based on the oil temperature measured by at least one oil temperature sensor (61-63). In this case, the fan controller 54 receives a sensor signal indicating the measured temperature of the oil from the first sensor 61, the second sensor 62, or the third sensor 63, and compares this measured temperature with a temperature threshold. This temperature threshold is set to a value at which oil cooling is evaluated to be insufficient if the oil temperature is higher than this threshold.
　オイル温度センサが測定するオイル温度が温度しきい値を超えるひとつの原因として、たとえば、液冷熱交換器２４に供給される冷却液の温度が高すぎる場合（すなわち、冷却液を冷却するチラーの冷却不良や故障）や、液冷熱交換器２４自身の不良（熱交換器の詰まりや破損）などが想定される。 One reason why the oil temperature measured by the oil temperature sensor exceeds the temperature threshold is, for example, if the temperature of the coolant supplied to the liquid-cooled heat exchanger 24 is too high (i.e., the temperature of the chiller that cools the coolant is too high). (defect or breakdown) or a defect in the liquid-cooled heat exchanger 24 itself (clogged or damaged heat exchanger).
　そこで、ファンコントローラ５４は、測定温度が温度しきい値を超える場合に空冷熱交換器２６を作動させる。すなわち、ファンコントローラ５４は、冷却ファン５０をオフからオンに切り替えることにより、空冷熱交換器２６を起動する。一方、ファンコントローラ５４は、測定温度が温度しきい値を超えない場合には、空冷熱交換器２６を起動しない（冷却ファン５０をオフのままとする）。このようにして、圧縮機１２の予備冷却装置である空冷熱交換器２６を作動させることにより、圧縮機１２の主冷却装置である液冷熱交換器２４の動作不良に対処することができる。 Therefore, the fan controller 54 operates the air-cooled heat exchanger 26 when the measured temperature exceeds the temperature threshold. That is, the fan controller 54 starts the air-cooled heat exchanger 26 by switching the cooling fan 50 from off to on. On the other hand, if the measured temperature does not exceed the temperature threshold, the fan controller 54 does not activate the air-cooled heat exchanger 26 (keeps the cooling fan 50 off). In this manner, by operating the air-cooled heat exchanger 26, which is a preliminary cooling device for the compressor 12, it is possible to cope with a malfunction of the liquid-cooled heat exchanger 24, which is the main cooling device for the compressor 12.
　あるいは、ファンコントローラ５４は、冷媒ガス温度センサによって測定される冷媒ガス温度に基づいて、冷却ファン５０を作動させてもよい。例えば、ファンコントローラ５４は、冷媒ガスの測定温度を示すセンサ信号を第４センサ６４、または第５センサ６５から受け、この測定温度を温度しきい値と比較してもよい。ファンコントローラ５４は、測定温度が温度しきい値を超える場合に空冷熱交換器２６を作動させる一方、測定温度が温度しきい値を超えない場合には空冷熱交換器２６を起動しない。このようにしても、空冷熱交換器２６を利用して、液冷熱交換器２４の動作不良に対処することができる。 Alternatively, the fan controller 54 may operate the cooling fan 50 based on the refrigerant gas temperature measured by the refrigerant gas temperature sensor. For example, the fan controller 54 may receive a sensor signal indicating the measured temperature of the refrigerant gas from the fourth sensor 64 or the fifth sensor 65, and may compare the measured temperature with a temperature threshold. Fan controller 54 activates air-cooled heat exchanger 26 when the measured temperature exceeds the temperature threshold, and does not activate air-cooled heat exchanger 26 when the measured temperature does not exceed the temperature threshold. Even in this case, malfunction of the liquid-cooled heat exchanger 24 can be dealt with using the air-cooled heat exchanger 26.
　ところで、極低温冷凍機１０の主たる用途の一つとして、超伝導マグネットの冷却がある。典型的には、超伝導マグネットは、大量の液体ヘリウムに浸漬することで冷却され、極低温冷凍機１０は、液体ヘリウムの冷却、再凝縮に利用される。こうした従来型の装置では、たとえ極低温冷凍機１０が停止したとしても、大量の液体ヘリウムがしばらくの間、超伝導マグネットの冷却を維持することができる。これに対して、近年、ヘリウム価格の高騰を背景として、大幅に液体ヘリウムの使用量を低減する超伝導マグネットの研究開発が進められている。こうした省ヘリウムタイプの超伝導装置では、極低温冷凍機１０の運転停止は超伝導マグネットの冷却の喪失に直結しがちである。 By the way, one of the main uses of the cryogenic refrigerator 10 is cooling superconducting magnets. Typically, a superconducting magnet is cooled by immersing it in a large amount of liquid helium, and the cryogenic refrigerator 10 is used to cool and recondense the liquid helium. In such conventional devices, even if the cryocooler 10 is shut down, large amounts of liquid helium can keep the superconducting magnet cool for some time. In response to this, in recent years, against the backdrop of the soaring price of helium, research and development has been progressing on superconducting magnets that can significantly reduce the amount of liquid helium used. In such a helium-saving type superconducting device, stopping operation of the cryogenic refrigerator 10 tends to directly lead to loss of cooling of the superconducting magnet.
　実施の形態によると、圧縮機冷却系２２が液冷熱交換器２４と空冷熱交換器２６を有するので、圧縮機１２の冷却に関して冗長性が確保される。たとえ液冷熱交換器２４に動作不良が生じたとしても、圧縮機１２の冷却機能を空冷熱交換器２６により補完または代替できる。よって、圧縮機１２の過剰な温度上昇およびそれに起因する極低温冷凍機１０の運転停止のリスクが低減される。したがって、実施の形態に係る極低温冷凍機１０は、いわゆる省ヘリウムタイプの超伝導装置の運転継続性を向上することに役立つ。 According to the embodiment, since the compressor cooling system 22 includes the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26, redundancy in cooling the compressor 12 is ensured. Even if the liquid-cooled heat exchanger 24 malfunctions, the cooling function of the compressor 12 can be supplemented or replaced by the air-cooled heat exchanger 26. Therefore, the risk of excessive temperature rise of the compressor 12 and the resulting shutdown of the cryogenic refrigerator 10 is reduced. Therefore, the cryogenic refrigerator 10 according to the embodiment is useful for improving the operational continuity of a so-called helium-saving type superconducting device.
　しかしながら、この実施の形態では、圧縮機冷却系２２が液冷式と空冷式の２つの熱交換器を搭載しているため（とくに、液冷熱交換器２４と空冷熱交換器２６が直列接続されているため）、冷却されるオイル循環ライン２０の全長が長くなりがちであり、これに起因してオイル流れの圧力損失が増加しうる。その結果生じうるオイル循環ライン２０のオイル流量低下は、圧縮機冷却系２２の冷却能力を低下させ、ひいては圧縮機１２のオーバーヒートや高温運転による寿命の低下を招きうる。とくに、液冷熱交換器２４に供給される冷却液の温度が低すぎる場合には、そのような低温でオイル粘度が非線形に増加しうることから、この問題が顕在化しやすい。とりうる方策として、例えば、オイルポンプをハイパワーで駆動する等、投入エネルギーを増加することによって、オイル循環ライン２０のオイル流量を回復させることが考えられる。しかし、これは望ましくないことに、消費電力を増加させることになる。 However, in this embodiment, since the compressor cooling system 22 is equipped with two heat exchangers, a liquid-cooled type and an air-cooled type (in particular, the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 are connected in series). Therefore, the total length of the oil circulation line 20 to be cooled tends to be long, which may increase the pressure loss of the oil flow. The resulting decrease in the oil flow rate in the oil circulation line 20 may reduce the cooling capacity of the compressor cooling system 22, which may lead to overheating of the compressor 12 and shortening of its life due to high temperature operation. In particular, if the temperature of the coolant supplied to the liquid-cooled heat exchanger 24 is too low, this problem is likely to occur because the oil viscosity may increase nonlinearly at such a low temperature. A possible measure is to restore the oil flow rate in the oil circulation line 20 by increasing the input energy, for example by driving the oil pump with high power. However, this undesirably increases power consumption.
　これに対処すべく、この実施の形態では、空冷熱交換器２６は、第１オイルライン４６のみを有するのではなく、第１オイルライン４６をバイパスする第２オイルライン４８をさらに備える。このように、空冷熱交換器２６に複数のオイル流路を並列に設けることにより、オイル循環ライン２０の流路断面積が増え、圧力損失を低減することができる。オイルが液冷熱交換器２４で低温に冷却され、液冷熱交換器２４から出るオイルの粘度が高まったとしても、空冷熱交換器２６を流れるオイル流量の低下を抑えることができる。オイル循環ライン２０を循環するオイル流量の不足を防ぎ、圧縮機１２の冷却不良を回避することができる。 In order to cope with this, in this embodiment, the air-cooled heat exchanger 26 does not have only the first oil line 46, but further includes a second oil line 48 that bypasses the first oil line 46. By providing a plurality of oil passages in parallel in the air-cooled heat exchanger 26 in this manner, the passage cross-sectional area of the oil circulation line 20 increases and pressure loss can be reduced. Even if the oil is cooled to a low temperature in the liquid-cooled heat exchanger 24 and the viscosity of the oil discharged from the liquid-cooled heat exchanger 24 increases, a decrease in the oil flow rate flowing through the air-cooled heat exchanger 26 can be suppressed. Insufficient flow of oil circulating through the oil circulation line 20 can be prevented, and insufficient cooling of the compressor 12 can be avoided.
　図２は、実施の形態に係る圧縮機１２のオイル循環ライン２０の一例を概略的に示す図である。図２の例においても、図１を参照して説明した実施の形態と同様に、圧縮機１２は、圧縮機本体１６、圧縮機冷却系２２、およびこれらを接続するオイル循環ライン２０を備える。圧縮機冷却系２２は、液冷熱交換器２４および空冷熱交換器２６を備え、オイル循環ライン２０を冷却するように構成されている。液冷熱交換器２４と空冷熱交換器２６は直列に接続され、液冷熱交換器２４が空冷熱交換器２６の上流に設けられている。 FIG. 2 is a diagram schematically showing an example of the oil circulation line 20 of the compressor 12 according to the embodiment. Also in the example of FIG. 2, similarly to the embodiment described with reference to FIG. 1, the compressor 12 includes a compressor main body 16, a compressor cooling system 22, and an oil circulation line 20 connecting these. The compressor cooling system 22 includes a liquid-cooled heat exchanger 24 and an air-cooled heat exchanger 26, and is configured to cool the oil circulation line 20. The liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 are connected in series, and the liquid-cooled heat exchanger 24 is provided upstream of the air-cooled heat exchanger 26.
　オイル循環ライン２０は、空冷熱交換器２６の上流、つまり液冷熱交換器２４と空冷熱交換器２６との間で、第１オイルライン４６と第２オイルライン４８に分岐する。空冷熱交換器２６は、冷却ファン５０を備え、第１オイルライン４６および第２オイルライン４８は、冷却ファン５０が作動するとき空冷熱交換器２６内に生じさせる空気流れによって強制冷却される。第１オイルライン４６と第２オイルライン４８は、空冷熱交換器２６の下流、つまり空冷熱交換器２６と圧縮機本体１６のオイル入口との間で再び合流する。 The oil circulation line 20 branches into a first oil line 46 and a second oil line 48 upstream of the air-cooled heat exchanger 26, that is, between the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26. The air-cooled heat exchanger 26 includes a cooling fan 50, and the first oil line 46 and the second oil line 48 are forcibly cooled by the air flow generated within the air-cooled heat exchanger 26 when the cooling fan 50 operates. The first oil line 46 and the second oil line 48 join together again downstream of the air-cooled heat exchanger 26, that is, between the air-cooled heat exchanger 26 and the oil inlet of the compressor body 16.
　空冷熱交換器２６は、第１オイルライン４６のオイル流量と第２オイルライン４８のオイル流量との差を低減するように第１オイルライン４６と第２オイルライン４８の少なくとも一方に設けられたオリフィス５６を備えてもよい。図２の例では、オリフィス５６が存在しなかった場合の第２オイルライン４８のオイル流量は、第１オイルライン４６に比べて多くなっている。そこで、オリフィス５６を第２オイルライン４８に設けることにより、第２オイルライン４８のオイル流量を低下させ、第１オイルライン４６と第２オイルライン４８のオイル流量を均一化することができる。第１オイルライン４６と第２オイルライン４８のオイル流量のアンバランスを解消し、空冷熱交換器２６の熱交換の効率を向上することができる。 The air-cooled heat exchanger 26 is provided in at least one of the first oil line 46 and the second oil line 48 so as to reduce the difference between the oil flow rate in the first oil line 46 and the oil flow rate in the second oil line 48. An orifice 56 may also be provided. In the example of FIG. 2, the oil flow rate in the second oil line 48 is larger than that in the first oil line 46 when the orifice 56 is not present. Therefore, by providing the orifice 56 in the second oil line 48, the oil flow rate in the second oil line 48 can be reduced and the oil flow rates in the first oil line 46 and the second oil line 48 can be equalized. It is possible to eliminate the imbalance in oil flow rates between the first oil line 46 and the second oil line 48, and improve the heat exchange efficiency of the air-cooled heat exchanger 26.
　発明者の検討によると、オリフィス５６の孔径直径Ｒ［ｍ］は、1.0×10-4(m)≦Ｒ≦5.0×10-2(m)の範囲から選択されてもよい。ここで、孔径直径Ｒは、次式により算出することができる。
Figure JPOXMLDOC01-appb-M000001
 　ここで、μは、空冷熱交換器に流入するオイルの粘度［Ｐａ・ｓ］、Ｌ１，Ｌ２はそれぞれ、第１オイルライン４６および第２オイルライン４８の空冷熱交換器としての長さ［ｍ］、ｄは、第１オイルライン４６および第２オイルライン４８の配管直径［ｍ］、Ｑは、オイル循環ライン２０のオイルの流量［ｍ３／ｓ］を表す。 According to the inventor's study, the hole diameter R [m] of the orifice 56 may be selected from the range of 1.0×10 −4 (m)≦R≦5.0×10 −2 (m). Here, the pore diameter R can be calculated using the following formula.
Figure JPOXMLDOC01-appb-M000001
 Here, μ is the viscosity [Pa・s] of the oil flowing into the air-cooled heat exchanger, and L 1 and L 2 are the lengths of the first oil line 46 and the second oil line 48 as the air-cooled heat exchanger, respectively. [m] and d represent the pipe diameters [m] of the first oil line 46 and the second oil line 48, and Q represents the oil flow rate [m 3 /s] of the oil circulation line 20.
　図３は、実施の形態に係る圧縮機１２のオイル循環ライン２０の他の一例を概略的に示す図である。図３の例においても、図１を参照して説明した実施の形態と同様に、圧縮機１２は、圧縮機本体１６、圧縮機冷却系２２、およびこれらを接続するオイル循環ライン２０を備える。圧縮機冷却系２２は、液冷熱交換器２４および空冷熱交換器２６を備え、オイル循環ライン２０を冷却するように構成されている。液冷熱交換器２４と空冷熱交換器２６は直列に接続され、液冷熱交換器２４が空冷熱交換器２６の上流に設けられている。 FIG. 3 is a diagram schematically showing another example of the oil circulation line 20 of the compressor 12 according to the embodiment. Also in the example of FIG. 3, similarly to the embodiment described with reference to FIG. 1, the compressor 12 includes a compressor main body 16, a compressor cooling system 22, and an oil circulation line 20 connecting these. The compressor cooling system 22 includes a liquid-cooled heat exchanger 24 and an air-cooled heat exchanger 26, and is configured to cool the oil circulation line 20. The liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 are connected in series, and the liquid-cooled heat exchanger 24 is provided upstream of the air-cooled heat exchanger 26.
　オイル循環ライン２０は、空冷熱交換器２６の上流、つまり液冷熱交換器２４と空冷熱交換器２６との間で、第１オイルライン４６と第２オイルライン４８に分岐する。空冷熱交換器２６は、冷却ファン５０を備え、第１オイルライン４６は、冷却ファン５０が作動するとき空冷熱交換器２６内に生じさせる空気流れによって強制冷却される。第１オイルライン４６と第２オイルライン４８は、空冷熱交換器２６の下流、つまり空冷熱交換器２６と圧縮機本体１６のオイル入口との間で再び合流する。 The oil circulation line 20 branches into a first oil line 46 and a second oil line 48 upstream of the air-cooled heat exchanger 26, that is, between the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26. The air-cooled heat exchanger 26 includes a cooling fan 50, and the first oil line 46 is forcibly cooled by the air flow generated within the air-cooled heat exchanger 26 when the cooling fan 50 operates. The first oil line 46 and the second oil line 48 join together again downstream of the air-cooled heat exchanger 26, that is, between the air-cooled heat exchanger 26 and the oil inlet of the compressor body 16.
　ただし、第２オイルライン４８は、図１および図２の例とは異なり、空冷熱交換器２６をバイパスする。第２オイルライン４８は、圧縮機１２において空冷熱交換器２６の外に設けられ、空冷熱交換器２６内を経由しない。 However, unlike the examples in FIGS. 1 and 2, the second oil line 48 bypasses the air-cooled heat exchanger 26. The second oil line 48 is provided outside the air-cooled heat exchanger 26 in the compressor 12 and does not pass through the air-cooled heat exchanger 26 .
　第２オイルライン４８は、冷却ファン５０を作動させるとき閉じ、冷却ファン５０を停止させるとき開くように動作する開閉弁５８を備えてもよい。そこで、ファンコントローラ５４は、少なくとも１つのセンサから当該センサの測定結果を示すセンサ信号を受け、測定結果に基づいて冷却ファン５０および開閉弁５８を作動させるように構成されてもよい。ファンコントローラ５４は、冷却ファン５０を作動させるとともに開閉弁５８を閉じ、冷却ファン５０を停止させるとともに開閉弁５８を開いてもよい。なお図３には、例として、第２センサ６２のセンサ信号がファンコントローラ５４に入力される場合を示している。上述のように、他のセンサ（例えば、第１センサ６１、または第３センサ６３、または第４センサ６４、または第５センサ６５）が用いられてもよい。 The second oil line 48 may include an on-off valve 58 that closes when the cooling fan 50 is activated and opens when the cooling fan 50 is stopped. Therefore, the fan controller 54 may be configured to receive a sensor signal indicating a measurement result from at least one sensor, and operate the cooling fan 50 and the on-off valve 58 based on the measurement result. The fan controller 54 may operate the cooling fan 50 and close the on-off valve 58, or may stop the cooling fan 50 and open the on-off valve 58. Note that FIG. 3 shows, as an example, a case where a sensor signal from the second sensor 62 is input to the fan controller 54. As mentioned above, other sensors (eg, first sensor 61, or third sensor 63, or fourth sensor 64, or fifth sensor 65) may be used.
　このようにして、圧縮機１２の主冷却装置である液冷熱交換器２４が正常に作動しているときには、予備冷却装置である空冷熱交換器２６は停止され、液冷熱交換器２４で冷却されたオイルは第２オイルライン４８を流れることになる。オイル流れに空冷熱交換器２６をバイパスさせることにより、オイル循環ライン２０の圧力損失の増加を抑制することができる。オイル循環ライン２０を循環するオイル流量の不足を防ぎ、圧縮機１２の冷却不良を回避することができる。 In this way, when the liquid-cooled heat exchanger 24, which is the main cooling device for the compressor 12, is operating normally, the air-cooled heat exchanger 26, which is the preliminary cooling device, is stopped, and the liquid-cooled heat exchanger 24 cools the compressor 12. The oil will flow through the second oil line 48. By bypassing the air-cooled heat exchanger 26 in the oil flow, an increase in pressure loss in the oil circulation line 20 can be suppressed. Insufficient flow of oil circulating through the oil circulation line 20 can be prevented, and insufficient cooling of the compressor 12 can be avoided.
　一方、液冷熱交換器２４が正常に作動していないときには、開閉弁５８を閉じて空冷熱交換器２６を作動させることにより、液冷熱交換器２４の冷却不良を空冷熱交換器２６により補完または代替できる。 On the other hand, when the liquid-cooled heat exchanger 24 is not operating normally, the on-off valve 58 is closed and the air-cooled heat exchanger 26 is operated to compensate for the cooling failure of the liquid-cooled heat exchanger 24 with the air-cooled heat exchanger 26. Can be replaced.
　なお、図３の例において、図１および図２の例と同様に、空冷熱交換器２６内に複数のオイルラインが設けられ、これらオイルラインが冷却ファン５０によって冷却されてもよい。 Note that in the example of FIG. 3, a plurality of oil lines may be provided in the air-cooled heat exchanger 26, and these oil lines may be cooled by the cooling fan 50, similarly to the examples of FIGS. 1 and 2.
　以上、本発明を実施例にもとづいて説明した。本発明は上記実施形態に限定されず、種々の設計変更が可能であり、様々な変形例が可能であること、またそうした変形例も本発明の範囲にあることは、当業者に理解されるところである。ある実施の形態に関連して説明した種々の特徴は、他の実施の形態にも適用可能である。組合せによって生じる新たな実施の形態は、組み合わされる実施の形態それぞれの効果をあわせもつ。 The present invention has been described above based on examples. It will be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that various design changes and modifications are possible, and that such modifications also fall within the scope of the present invention. By the way. Various features described in connection with one embodiment are also applicable to other embodiments. A new embodiment resulting from a combination has the effects of each of the combined embodiments.
　上述の実施の形態では、オイル循環ライン２０は、空冷熱交換器２６において第１オイルライン４６と第２オイルライン４８に分岐しているが、例えば３つまたは４つなど、より多くのオイルラインに分岐してもよい。 In the embodiment described above, the oil circulation line 20 branches into a first oil line 46 and a second oil line 48 at the air-cooled heat exchanger 26, but there are more oil lines, for example three or four. You may branch to
　上述の実施の形態では、圧縮機冷却系２２において液冷熱交換器２４と空冷熱交換器２６が直列接続され、液冷熱交換器２４が空冷熱交換器２６の上流に設けられている。しかし、圧縮機冷却系２２は、他の構成もとりうる。例えば、液冷熱交換器２４と空冷熱交換器２６が直列接続され、空冷熱交換器２６が液冷熱交換器２４の上流に設けられてもよい。あるいは、液冷熱交換器２４と空冷熱交換器２６が並列接続されてもよい。 In the embodiment described above, the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 are connected in series in the compressor cooling system 22, and the liquid-cooled heat exchanger 24 is provided upstream of the air-cooled heat exchanger 26. However, the compressor cooling system 22 may have other configurations. For example, the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 may be connected in series, and the air-cooled heat exchanger 26 may be provided upstream of the liquid-cooled heat exchanger 24. Alternatively, the liquid-cooled heat exchanger 24 and the air-cooled heat exchanger 26 may be connected in parallel.
　空冷熱交換器２６の冷却ファン５０は、上述の例とは冷却ファンは逆向きの空気流れを生成してもよく、外部から空冷熱交換器２６内へと送風するように構成されてもよい。冷却ファン５０は、冷媒ガスライン１８、第１オイルライン４６、第２オイルライン４８に空気を吹き付けるように構成されてもよい。 The cooling fan 50 of the air-cooled heat exchanger 26 may generate an air flow in the opposite direction from the example described above, and may be configured to blow air into the air-cooled heat exchanger 26 from the outside. . The cooling fan 50 may be configured to blow air onto the refrigerant gas line 18, the first oil line 46, and the second oil line 48.
　実施の形態にもとづき、具体的な語句を用いて本発明を説明したが、実施の形態は、本発明の原理、応用の一側面を示しているにすぎず、実施の形態には、請求の範囲に規定された本発明の思想を逸脱しない範囲において、多くの変形例や配置の変更が認められる。 Although the present invention has been described using specific words based on the embodiments, the embodiments merely illustrate one aspect of the principles and applications of the present invention, and the embodiments do not include the claims. Many modifications and changes in arrangement are possible without departing from the spirit of the invention as defined in scope.
　本発明は、オイル潤滑式の極低温冷凍機用圧縮機の分野における利用が可能である。 The present invention can be used in the field of oil-lubricated compressors for cryogenic refrigerators.
　１０　極低温冷凍機、　１２　圧縮機、　１８　冷媒ガスライン、　２４　液冷熱交換器、　２６　空冷熱交換器、　４６　第１オイルライン、　４８　第２オイルライン、　５０　冷却ファン、　５６　オリフィス、　５８　開閉弁。 10 Cryogenic refrigerator, 12 Compressor, 18 Refrigerant gas line, 24 Liquid-cooled heat exchanger, 26 Air-cooled heat exchanger, 46 First oil line, 48 Second oil line, 50 Cooling fan, 56 Orifice, 58 Open/close valve.

Claims (9)

  1. 　オイル潤滑式の極低温冷凍機用圧縮機であって、
    　冷却ファンと、前記冷却ファンによって強制冷却されるように配置された第１オイルラインとを備える空冷熱交換器と、
    　前記第１オイルラインをバイパスする第２オイルラインと、を備えることを特徴とするオイル潤滑式の極低温冷凍機用圧縮機。     An oil-lubricated compressor for a cryogenic refrigerator,
    an air-cooled heat exchanger comprising a cooling fan and a first oil line arranged to be forcibly cooled by the cooling fan;
    An oil-lubricated compressor for a cryogenic refrigerator, comprising: a second oil line that bypasses the first oil line.
  2. 　前記第２オイルラインは、前記冷却ファンによって強制冷却されるように配置されていることを特徴とする請求項１に記載のオイル潤滑式の極低温冷凍機用圧縮機。 The oil-lubricated compressor for a cryogenic refrigerator according to claim 1, wherein the second oil line is arranged so as to be forcibly cooled by the cooling fan.
  3. 　前記空冷熱交換器は、前記第１オイルラインのオイル流量と前記第２オイルラインのオイル流量との差を低減するように前記第１オイルラインと前記第２オイルラインの少なくとも一方に設けられたオリフィスを備えることを特徴とする請求項２に記載のオイル潤滑式の極低温冷凍機用圧縮機。 The air-cooled heat exchanger is provided in at least one of the first oil line and the second oil line so as to reduce the difference between the oil flow rate in the first oil line and the oil flow rate in the second oil line. The oil-lubricated compressor for a cryogenic refrigerator according to claim 2, further comprising an orifice.
  4. 　前記第２オイルラインは、前記空冷熱交換器をバイパスすることを特徴とする請求項１に記載のオイル潤滑式の極低温冷凍機用圧縮機。 The oil-lubricated compressor for a cryogenic refrigerator according to claim 1, wherein the second oil line bypasses the air-cooled heat exchanger.
  5. 　前記第２オイルラインは、前記冷却ファンを作動させるとき閉じ、前記冷却ファンを停止させるとき開くように動作する開閉弁を備えることを特徴とする請求項４に記載のオイル潤滑式の極低温冷凍機用圧縮機。 5. The oil-lubricated cryogenic refrigeration system according to claim 4, wherein the second oil line includes an on-off valve that closes when the cooling fan is activated and opens when the cooling fan is stopped. Machine compressor.
  6. 　前記空冷熱交換器は、冷媒ガスラインを冷却することを特徴とする請求項１に記載のオイル潤滑式の極低温冷凍機用圧縮機。 The oil-lubricated compressor for a cryogenic refrigerator according to claim 1, wherein the air-cooled heat exchanger cools a refrigerant gas line.
  7. 　前記空冷熱交換器の上流に直列接続された液冷熱交換器をさらに備えることを特徴とする請求項１から６のいずれかに記載のオイル潤滑式の極低温冷凍機用圧縮機。 The oil-lubricated compressor for a cryogenic refrigerator according to any one of claims 1 to 6, further comprising a liquid-cooled heat exchanger connected in series upstream of the air-cooled heat exchanger.
  8. 　前記液冷熱交換器の上流または下流、または前記空冷熱交換器の下流に設けられたオイル温度センサをさらに備え、
    　前記冷却ファンは、前記オイル温度センサによって測定されるオイル温度に基づいて作動することを特徴とする請求項７に記載のオイル潤滑式の極低温冷凍機用圧縮機。     Further comprising an oil temperature sensor provided upstream or downstream of the liquid-cooled heat exchanger, or downstream of the air-cooled heat exchanger,
    The oil-lubricated compressor for a cryogenic refrigerator according to claim 7, wherein the cooling fan operates based on the oil temperature measured by the oil temperature sensor.
  9. 　前記液冷熱交換器は、冷媒ガスライン上で前記液冷熱交換器の上流または下流に設けられた冷媒ガス温度センサをさらに備え、
    　前記冷却ファンは、前記冷媒ガス温度センサによって測定される冷媒ガス温度に基づいて作動することを特徴とする請求項７に記載のオイル潤滑式の極低温冷凍機用圧縮機。     The liquid-cooled heat exchanger further includes a refrigerant gas temperature sensor provided upstream or downstream of the liquid-cooled heat exchanger on the refrigerant gas line,
    The oil-lubricated compressor for a cryogenic refrigerator according to claim 7, wherein the cooling fan operates based on the refrigerant gas temperature measured by the refrigerant gas temperature sensor.
PCT/JP2023/015355 2022-05-11 2023-04-17 Oil lubrication-type compressor for cryocooler WO2023218865A1 (en)

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Citations (3)

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JP2011099669A (en) * 2009-11-09 2011-05-19 Sumitomo Heavy Ind Ltd Air cooled helium compressor
US20170175743A1 (en) * 2015-12-18 2017-06-22 Sumitomo (Shi) Cryogenics Of America, Inc. Cold start helium compressor
JP2019505751A (en) * 2015-12-18 2019-02-28 スミトモ （エスエイチアイ） クライオジェニックス オブ アメリカ インコーポレイテッドＳｕｍｉｔｏｍｏ（ＳＨＩ）Ｃｒｙｏｇｅｎｉｃｓ ｏｆ Ａｍｅｒｉｃａ，Ｉｎｃ． Helium compressor with dual aftercooler

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011099669A (en) * 2009-11-09 2011-05-19 Sumitomo Heavy Ind Ltd Air cooled helium compressor
US20170175743A1 (en) * 2015-12-18 2017-06-22 Sumitomo (Shi) Cryogenics Of America, Inc. Cold start helium compressor
JP2019505751A (en) * 2015-12-18 2019-02-28 スミトモ （エスエイチアイ） クライオジェニックス オブ アメリカ インコーポレイテッドＳｕｍｉｔｏｍｏ（ＳＨＩ）Ｃｒｙｏｇｅｎｉｃｓ ｏｆ Ａｍｅｒｉｃａ，Ｉｎｃ． Helium compressor with dual aftercooler

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