Compressor unit of cryogenic refrigerator

Abstract

The present invention addresses the problem of improving the energy-saving performance of a cryogenic refrigerator. The invention provides a compressor unit of a cryogenic refrigerator. The compressor unit comprises a compressor motor; an inverter (60) that converts alternating current input from an external power source to the compressor unit into a drive power source for the compressor motor; a transformer (62) for converting the alternating current into a driving power source for the cold head of the cryogenic refrigerator having a voltage different from the voltage of the alternating current; and a control panel (50) on which the inverter (60) and the transformer (62) are mounted. The transformer (62) may be disposed below the inverter (60).

Description

[0001] This application claims priority based on Japanese Patent Application No. 2024-011966 filed on January 30, 2024. The entire content of the Japanese application is incorporated herein by reference. Technical Field

[0002] The present invention relates to a compressor unit of a cryogenic refrigerator. Background Art

[0003] Generally, a cryogenic refrigerator such as a Gifford-McMahon (GM) refrigerator includes a compressor for refrigerant gas to supply high-pressure refrigerant gas to a cold head. The compressor includes components such as a compressor body, an oil separator, an adsorber, a storage tank, and a control device.

[0004] Patent Document 1: Japanese Patent Laid-Open No. 2001-74326

[0005] In the above cryogenic refrigerator, the motor driving the compressor operates at a constant speed. Summary of the Invention

[0006] One exemplary object of an embodiment of the present invention is to improve the energy efficiency of a cryogenic refrigerator.

[0007] According to an embodiment of the present invention, a compressor unit of a cryogenic refrigerator includes: a compressor motor; an inverter that converts alternating current input from an external power source into a driving power source for the compressor motor; a transformer that converts alternating current into a driving power source for a cold head of the cryogenic refrigerator having a voltage different from that of the alternating current; and a control panel on which the inverter and the transformer are mounted.

[0008] According to this embodiment, since the rotational speed of the compressor motor can be adjusted by the inverter, the energy efficiency of the compressor unit of the cryogenic refrigerator can be improved. Also, although the alternating current input according to the country or region where the cryogenic refrigerator is used may have different voltages, it can be converted into a voltage suitable for the cold head by the transformer, and the compressor unit can be used as a power source for the cold head.

[0009] The inverter may have an inverter exhaust port that serves as an outlet for cooling air from the inverter, and the inverter is mounted on the control panel such that the inverter exhaust port is located above the transformer.

[0010] The transformer may be disposed at a position lower than the inverter.

[0011] The compressor unit may further include a switching power supply that converts alternating current into direct current. The switching power supply may be mounted on the control panel.

[0012] The frequency converter may have a frequency converter exhaust port which serves as an outlet for the cooling air from the frequency converter, and the frequency converter is mounted on the control panel in such a manner that the frequency converter exhaust port is located at a position higher than the switching power supply.

[0013] The compressor unit may further include a noise filter and a DC reactor connected to the frequency converter. The noise filter and the DC reactor may be mounted on the control panel.

[0014] The frequency converter may have a frequency converter exhaust port which serves as an outlet for the cooling air from the frequency converter, and the frequency converter is mounted on the control panel in such a manner that the frequency converter exhaust port is located at a position higher than the noise filter and the DC reactor.

[0015] The noise filter and the DC reactor may be arranged at a position lower than the frequency converter and higher than the transformer.

[0016] The frequency converter may have a frequency converter exhaust port which serves as an outlet for the cooling air from the frequency converter. The compressor unit may further include a compressor unit housing which has a housing exhaust port serving as an outlet for the cooling air from the compressor unit and houses the compressor motor and the control panel. The control panel may include an exhaust passage defining a flow path for the cooling air leading from the frequency converter exhaust port to the housing exhaust port. The exhaust passage includes a passage inlet member adjacent to the frequency converter exhaust port and a passage outlet member adjacent to the housing exhaust port, and the passage inlet member may be detached from the passage outlet member and the frequency converter.

[0017] The compressor unit housing may have a housing inlet port which is arranged at a position lower than the housing exhaust port and serves as an inlet for the cooling air leading to the compressor unit.

[0018] Compared with the transformer, the frequency converter may be arranged closer to the housing exhaust port, and compared with the frequency converter, the transformer may be arranged closer to the housing inlet port.

[0019] The occupied space of the compressor unit may fall within a region having a width of 600 mm or less and a length of 500 mm or less.

[0020] Advantageous Effects of the Invention

[0021] According to the present invention, the energy saving performance of the ultra-low temperature refrigerator can be improved. Description of the Drawings

[0022] Figure 1 It is a diagram schematically showing the ultra-low temperature refrigerator according to the embodiment.

[0023] Figure 2It is a diagram schematically showing the appearance of the compressor unit of the ultra-low temperature refrigerator according to the embodiment.

[0024] Figure 3 It is a diagram schematically showing the appearance of the compressor unit of the ultra-low temperature refrigerator according to the embodiment.

[0025] Figure 4 It is a schematic top view showing the equipment arrangement inside the compressor unit of the ultra-low temperature refrigerator according to the embodiment.

[0026] Figure 5 It is a block diagram schematically showing the control panel of the compressor unit according to the embodiment.

[0027] Figure 6 It is a diagram schematically showing the appearance of the compressor unit according to the embodiment.

[0028] Figure 7 It is a diagram schematically showing the equipment arrangement on the control panel of the compressor unit according to the embodiment.

[0029] Figure 8 It is a diagram schematically showing the appearance of the compressor unit of the ultra-low temperature refrigerator according to the embodiment.

[0030] Figure 9 It is a diagram schematically showing the equipment arrangement on the control panel of the compressor unit according to the embodiment.

[0031] Figure 10 It is a diagram schematically showing another example of the exhaust passage mounted on the control panel according to the embodiment.

[0032] In the figure: 10 - ultra-low temperature refrigerator, 12 - compressor, 14 - cold head, 24 - compressor unit housing, 28 - compressor motor, 50 - control panel, 60 - frequency converter, 62 - transformer, 64 - noise filter, 66 - DC reactor, 68 - switching power supply, 72 - housing air inlet, 74 - housing air outlet, 78 - frequency converter exhaust port, 80 - exhaust passage. Detailed Embodiment

[0033] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and drawings, the same or equivalent components, parts, and processes are denoted by the same reference numerals, and repeated descriptions are appropriately omitted. In each drawing, for the sake of convenience of explanation, the scales or shapes of each part are appropriately set, and unless otherwise specifically mentioned, it is not to be construed as limiting. The embodiment is an example and does not limit the scope of the present invention in any way. All features or combinations thereof described in the embodiment are not necessarily the essence of the invention.

[0034] Figure 1FIG. 0 is a diagram schematically showing a cryogenic refrigerator according to an embodiment. The cryogenic refrigerator 10 is used to provide cryogenic cooling for an object or a medium. For example, the cryogenic refrigerator 10 can be used as a cooling source for a superconducting magnet device. The superconducting magnet device can be mounted on a high magnetic field utilization device as a magnetic field source of, for example, a single crystal pulling device, an NMR (Nuclear Magnetic Resonance) system, an MRI (Magnetic Resonance Imaging) system, an accelerator such as a cyclotron, a high energy physics system such as a nuclear fusion system, or other high magnetic field utilization devices (not shown), so as to generate a high magnetic field required for the device.

[0035] The cryogenic refrigerator 10 includes a compressor 12 and a cold head 14. The compressor 12 is configured to recover the refrigerant gas of the cryogenic refrigerator 10 from the cold head 14, boost the recovered refrigerant gas, and then supply the refrigerant gas back to the cold head 14. The compressor 12 is also referred to as a compressor unit. The cold head 14 is also referred to as an expander and has a room temperature part 14a and a low temperature part 14b. The low temperature part 14b is also referred to as a cooling table. The refrigerant gas is also referred to as a working gas, usually helium, but other suitable gases can also be used. The compressor 12 and the cold head 14 form a refrigeration cycle of the cryogenic refrigerator 10, whereby the low temperature part 14b is cooled to a desired cryogenic temperature. The low temperature part 14b can cool a cooled object such as a superconducting magnet, for example.

[0036] As an example, the cryogenic refrigerator 10 is a single-stage or two-stage Gifford-McMahon (GM) refrigerator, but can also be a pulse tube refrigerator, a Stirling refrigerator, or other types of cryogenic refrigerators. The cold head 14 has different structures according to the type of the cryogenic refrigerator 10, but the compressor 12 can use the structure described below regardless of the type of the cryogenic refrigerator 10.

[0037] In addition, 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 much higher than the atmospheric pressure, and can be respectively referred to as the first high pressure and the second high pressure. For the convenience of description, the first high pressure and the second high pressure are respectively abbreviated as the high pressure and the low pressure. Typically, the high pressure is, for example, 2 - 3 MPa. The low pressure is, for example, 0.5 - 1.5 MPa, for example, about 0.8 MPa.

[0038] The compressor 12 is an oil-lubricated compressor for a cryogenic refrigerator, and includes a compressor main body 16, a refrigerant gas pipeline 18, and an oil circulation pipeline 20. For the convenience of understanding, in Figure 1In this case, a solid line is used to represent the refrigerant gas pipeline 18, and a dashed line is used to represent the oil circulation pipeline 20. Moreover, the compressor 12 includes a compressor unit housing 24 that houses each component of the compressor 12, such as the compressor main body 16, the refrigerant gas pipeline 18, and the oil circulation pipeline 20.

[0039] The compressor main body 16 is configured to compress the refrigerant gas inhaled from its suction port inside and discharge it from the discharge port. In the compressor main body 16, oil is used for cooling and lubrication, and the inhaled refrigerant gas is directly exposed to this oil inside the compressor main body 16. Therefore, the refrigerant gas is sent out from the discharge port in a state of being mixed with a little oil.

[0040] The compressor main body 16 can adopt, for example, a scroll pump, a rotary pump, or other pumps that boost the pressure of the refrigerant gas. The compressor main body 16 can be configured to discharge a constant refrigerant gas flow rate. Or, the compressor main body 16 can also be configured to make the discharged refrigerant gas flow rate variable. The compressor main body 16 is also referred to as a compression chamber.

[0041] The refrigerant gas pipeline 18 includes a discharge port 30, a suction port 31, a discharge flow path 32, and a suction flow path 33. The discharge port 30 is an outlet of the refrigerant gas provided on the compressor unit housing 24 for sending out the refrigerant gas boosted to a high pressure by the compressor main body 16 from the compressor 12, and the suction port 31 is an inlet of the refrigerant gas provided on the compressor unit housing 24 for receiving the low-pressure refrigerant gas into the compressor 12. The discharge flow path 32 and the suction flow path 33 are accommodated inside the compressor unit housing 24. The discharge port of the compressor main body 16 is connected to the discharge port 30 through the discharge flow path 32, and the suction port 31 is connected to the suction port of the compressor main body 16 through the suction flow path 33.

[0042] The refrigerant gas pipeline 18 is connected to the cold head 14. A high-pressure port 40 and a low-pressure port 41 are provided at the room-temperature part 14a of the cold head 14. The high-pressure port 40 is connected to the discharge port 30 through a high-pressure pipe 42, and the low-pressure port 41 is connected to the suction port 31 through a low-pressure pipe 43.

[0043] An oil separator 34 and an adsorber 35 are provided on the discharge flow path 32. The purpose of setting the oil separator 34 is to separate the oil mixed into the refrigerant gas when passing through the compressor main body 16 from the refrigerant gas. The purpose of setting the adsorber 35 is to remove, by adsorption, residual components such as vaporized oil or other contaminants remaining in the refrigerant gas from the refrigerant gas. The oil separator 34 and the adsorber 35 are connected in series. On the discharge flow path 32, the oil separator 34 is arranged on the side of the compressor main body 16, and the adsorber 35 is arranged on the side of the discharge port 30.

[0044] An oil return pipeline 21 is provided to connect the oil separator 34 to the compressor body 16. Through the oil return pipeline 21, the oil recovered by the oil separator 34 can be returned to the compressor body 16. A filter for removing dust contained in the oil separated by the oil separator 34 and a throttle hole for controlling the amount of oil returned to the compressor body 16 can be provided in the middle of the oil return pipeline 21.

[0045] On the other hand, a storage tank 36 is provided on the suction flow path 33. The storage tank 36 is set to have a volume for removing pulsation contained in the low-pressure refrigerant gas returned from the cold head 14 to the compressor 12.

[0046] Moreover, a bypass valve 38 is provided on the refrigerant gas pipeline 18 to connect the discharge flow path 32 to the suction flow path 33 in a way that bypasses the compressor body 16. As an example, the bypass valve 38 branches from the discharge flow path 32 between the oil separator 34 and the adsorber 35 and is connected to the suction flow path 33 between the compressor body 16 and the storage tank 36. The purpose of setting the bypass valve 38 is to control the refrigerant gas flow rate and / or to equalize the pressure between the discharge flow path 32 and the suction flow path 33 when the compressor 12 stops.

[0047] The oil circulation pipeline 20 connects the oil outlet of the compressor body 16 to the oil inlet so that the oil flowing out of the compressor body 16 can return to the compressor body 16 again. A throttle hole for controlling the oil flow rate flowing through the inside can be provided on the oil circulation pipeline 20. Also, a filter for removing dust contained in the oil can be provided on the oil circulation pipeline 20.

[0048] Furthermore, the compressor 12 also includes a heat exchanger 22, which is accommodated in the compressor unit housing 24 and cools the compressor 12. The heat exchanger 22 includes: a refrigerant gas cooler 22a that cools the refrigerant gas pipeline 18 through heat exchange between the refrigerant gas and a cooling medium (such as cooling water); and an oil cooler 22b that cools the oil circulation pipeline 20 through heat exchange between the oil and the cooling medium.

[0049] The refrigerant gas cooler 22a is disposed between the compressor main body 16 and the oil separator 34 on the discharge flow path 32, and cools the high-pressure refrigerant gas heated by the compression heat generated by the compression of the refrigerant gas in the compressor main body 16. The refrigerant gas cooler 22a cools the refrigerant gas through heat exchange between the refrigerant gas and the cooling medium. The cooled refrigerant gas is purified in the oil separator 34 and the adsorber 35. Further, the oil cooler 22b cools the oil through heat exchange between the oil flowing out from the oil outlet of the compressor main body 16 to the oil circulation pipe 20 and the cooling medium. The cooled oil returns from the oil inlet of the compressor main body 16 into the compressor main body 16. The cooling medium is supplied to the compressor 12 from the outside through the cooling medium inlet 44, and is discharged to the outside of the compressor 12 through the refrigerant gas cooler 22a and the oil cooler 22b via the cooling medium outlet 45. The cooling medium may be a coolant, such as water. Thus, the compression heat generated in the compressor main body 16 is discharged to the outside of the compressor 12 together with the cooling medium. Additionally, the cooling medium may be cooled by a chiller (not shown) and then supplied again.

[0050] Further, the cryogenic refrigerator 10 includes a control panel 50. The control panel 50 is mounted on the compressor 12 as a control device for controlling the cryogenic refrigerator 10. The control panel 50 may include a control circuit configured to receive outputs from various sensors provided on the cryogenic refrigerator 10 and control various devices of the cryogenic refrigerator 10 based on the sensor outputs. A plurality of electrical mounting components including sensors may be housed together with the control panel 50 in the compressor unit housing 24. Each sensor may be connected to the control panel 50 through a communication cable. The electrical mounting components controlled according to the sensor outputs may include, for example, a compressor motor 28 that drives the compressor main body 16, a bypass valve 38, a cold head motor that drives the cold head 14, and the like.

[0051] Various sensors such as a pressure sensor and a temperature sensor may be provided on the compressor 12 to grasp the state of the compressor 12. For example, the first pressure sensor 37a may be disposed on the discharge flow path 32 to measure the pressure of the refrigerant gas flowing through the discharge flow path 32. The first pressure sensor 37a is configured to output a first measurement pressure signal PH indicating the measured pressure to the control panel 50. Further, the second pressure sensor 37b may be disposed on the suction flow path 33 to measure the pressure of the refrigerant gas flowing through the suction flow path 33. The second pressure sensor 37b is configured to output a second measurement pressure signal PL indicating the measured pressure to the control panel 50.

[0052] The temperature sensors may include a refrigerant gas temperature sensor disposed on the refrigerant gas pipeline 18, an oil temperature sensor disposed on the oil circulation pipeline 20, a coolant temperature sensor disposed on the coolant pipeline of the heat exchanger 22, a cooling temperature sensor disposed on the low-temperature part 14b of the cold head 14, etc. The temperature sensors are configured to output a signal indicating the measured temperature to the control panel 50.

[0053] For example, as Figure 1 shown, the first temperature sensor 46 is disposed upstream of the heat exchanger 22 on the discharge flow path 32 of the refrigerant gas pipeline 18 to measure the temperature of the refrigerant gas flowing from the compressor main body 16 into the heat exchanger 22. The second temperature sensor 47 is disposed downstream of the heat exchanger 22 on the refrigerant gas pipeline 18 to measure the temperature of the refrigerant gas flowing from the heat exchanger 22 into the oil separator 34. The third temperature sensor 48 is disposed upstream of the heat exchanger 22 on the oil circulation pipeline 20 to measure the temperature of the oil flowing from the compressor main body 16 into the heat exchanger 22. The fourth temperature sensor 49 is disposed downstream of the heat exchanger 22 on the oil circulation pipeline 20 to measure the temperature of the oil flowing from the heat exchanger 22 into the compressor main body 16.

[0054] During the operation of the cryogenic refrigerator 10, the refrigerant gas is supplied from the compressor 12 to the cold head 14, and a refrigeration cycle (such as the GM cycle) is constituted by the periodic volume change of the expansion space of the refrigerant gas in the cold head 14 and the synchronous pressure change of the refrigerant gas in the expansion space, and the low-temperature part 14b of the cold head 14 is cooled to the desired cryogenic temperature. For example, when the cold head 14 is of a two-stage type, the first-stage cooling table is cooled to a first cooling temperature in the range of about 30K to about 80K, and the second-stage cooling table is cooled to a second cooling temperature lower than the first cooling temperature, for example, cooled to 1K to 20K. The second cooling temperature may be the liquid helium temperature of about 4.2K or a lower temperature than that.

[0055] The refrigerant gas recovered from the cold head 14 to the compressor 12 flows into the suction port 31 of the compressor 12 through the low-pressure port 41 via the low-pressure pipeline 43. The refrigerant gas is recovered into the suction port of the compressor main body 16 after passing through the storage tank 36 on the suction flow path 33. The refrigerant gas is compressed by the compressor main body 16 to increase the pressure. At this time, the refrigerant gas is heated based on the compression heat. The refrigerant gas sent out from the discharge port of the compressor main body 16 is cooled in the refrigerant gas cooler 22a of the heat exchanger 22, and then leaves the compressor 12 from the discharge port 30 after passing through the oil separator 34 and the adsorber 35. The refrigerant gas is supplied to the inside of the cold head 14 via the high-pressure pipeline 42 and the high-pressure port 40.

[0056] Figure 2 and Figure 3This is a diagram schematically showing the appearance of a compressor unit of a cryogenic refrigerator according to an embodiment. Figure 2 A perspective view as seen from the rear of the compressor 12 is shown. Figure 3 The front of the compressor 12 is shown.

[0057] As Figure 2 shown, the compressor unit housing 24 has a rectangular parallelepiped shape with six faces, that is, it includes a front panel 24a, a rear panel 24b, a top panel 24c, a bottom panel 24d, and two left and right side panels 24e, 24f. The rear panel 24b faces the side opposite to the front panel 24a. Between the front panel 24a and the rear panel 24b, the top panel 24c is arranged above, the bottom panel 24d is arranged below, and the side panels 24e, 24f are arranged on the left and right. These panels are thin plate-like components formed of a metal such as stainless steel or other suitable materials.

[0058] The front panel 24a is configured to provide a user interface. As Figure 3 shown, a discharge port 30, a suction port 31, a coolant inlet 44, and a coolant outlet 45 are provided on the front panel 24a. And an input power connector 51, a communication cable connector 52, a cold head connector 53, and a main switch 54 are also provided on the front panel 24a.

[0059] As an exemplary structure, the front panel 24a may include two panel portions that are combined to form the front panel 24a. Specifically, it may include a first panel portion 24a1 and a second panel portion 24a2. The second panel portion 24a2 is mounted on the first panel portion 24a1. As Figure 3 shown, the second panel portion 24a2 may be provided on the left side of the front panel 24a.

[0060] In this example, the first panel portion 24a1 provides piping connection. That is, the discharge port 30, the suction port 31, the coolant inlet 44, and the coolant outlet 45 are provided on the first panel portion 24a1. The discharge port 30 and the suction port 31 are arranged at the upper part of the first panel portion 24a1, and the coolant inlet 44 and the coolant outlet 45 are arranged at the lower part of the first panel portion 24a1. Thus, the inlets and outlets of fluids such as refrigerant gas in the compressor 12 are concentrated on the first panel portion 24a1. No such fluid inlets and outlets are provided on the second panel portion 24a2.

[0061] Considering the operability when connecting the high-pressure pipe 42 and the low-pressure pipe 43 to the discharge port 30 and the suction port 31 respectively, the discharge port 30 and the suction port 31 are arranged as follows: the distance between the centers of the discharge port 30 and the suction port 31 has a gap of, for example, 5 cm to 20 cm.

[0062] The cooling medium inlet 44 and the cooling medium outlet 45 are arranged at a position lower than the input power connector 51 and the communication cable connector 52 in the height direction ( Figure 3 the up-and-down direction therein).

[0063] Moreover, the communication cable connector 52 is provided on the first panel portion 24a1. The communication cable connector 52 is connected to an external device through a communication cable, whereby communication can be performed between the compressor 12 and the external device. The communication cable connector 52 is arranged at a position on the first panel portion 24a1 that is higher than the discharge port 30 and the suction port 31.

[0064] And, the second panel portion 24a2 provides power connection. The input power connector 51, the cold head connector 53, and the main switch 54 are provided on the second panel portion 24a2. The input power connector 51 is connected to an external power source such as a commercial power supply to supply power to the cryogenic refrigerator 10. An electrical wiring is connected to the cold head connector 53 to supply power to the cold head 14 and control the cold head 14. Through this electrical wiring, an electrical connection is established between the compressor 12 and the cold head 14. The main switch 54 is a switch for switching on and off the cryogenic refrigerator 10. When the main switch 54 is turned on, the compressor 12 and the cold head 14 operate, and when the main switch 54 is turned off, the operation of the compressor 12 and the cold head 14 stops. The cold head connector 53 is arranged at the upper part of the second panel portion 24a2, and the input power connector 51 and the main switch 54 are arranged at the lower part of the second panel portion 24a2.

[0065] As Figure 2 shown, casters 26 can be installed on the bottom panel 24d to facilitate the movement or handling of the compressor 12. The four casters 26 can be respectively arranged at the four corners of the bottom panel 24d.

[0066] Figure 4 is a schematic top view showing the equipment arrangement inside the compressor unit of the cryogenic refrigerator according to the embodiment. In Figure 4 is shown the state where the top panel 24c is removed from the compressor unit housing 24. And, for convenience, in each drawing, the piping between the components connecting the compressor 12 is omitted.

[0067] As described above, the compressor 12 includes a compressor main body 16, a heat exchanger 22, an oil separator 34, an adsorber 35, a storage tank 36, and a control panel 50, and these components are accommodated inside the compressor unit housing 24. The front panel 24a of the compressor unit housing 24 has a first panel portion 24a1 and a second panel portion 24a2.

[0068] As Figure 4As shown, the oil separator 34, the adsorber 35, and the storage tank 36 are arranged on the side panel 24e side between the front panel 24a and the rear panel 24b. In other words, the oil separator 34, the adsorber 35, and the storage tank 36 are arranged between the first panel portion 24a1 of the front panel 24a and the rear panel 24b. Also, the compressor main body 16 and the control panel 50 are arranged on the side panel 24f side between the front panel 24a and the rear panel 24b. The compressor main body 16 and the control panel 50 are arranged between the second panel portion 24a2 of the front panel 24a and the rear panel 24b.

[0069] The control panel 50 is installed on the second panel portion 24a2 of the front panel 24a and is supported by the compressor unit housing 24. The control panel 50 can also be installed on the side panel 24f. The compressor main body 16, the oil separator 34, the adsorber 35, and the storage tank 36 are provided on the bottom panel 24d and are supported by the compressor unit housing 24.

[0070] The heat exchanger 22 is arranged close to the rear panel 24b. The heat exchanger 22 is arranged along the rear panel 24b behind the compressor main body 16 and the oil separator 34. Additionally, as another configuration example of the heat exchanger 22, for example, it can be configured to surround components of the compressor 12 such as the storage tank 36 arranged within the compressor unit housing 24. For example, the heat exchanger 22 can be wound around the storage tank 36.

[0071] Figure 5 It is a block diagram schematically showing the control panel of the compressor unit according to the embodiment. A frequency converter 60, a transformer 62, a noise filter 64, a DC reactor 66, a switching power supply 68, and a controller 70 are mounted on the control panel 50.

[0072] The frequency converter 60 converts the alternating current input from an external power source into the driving power for the compressor motor 28. As described above, the external power source is connected to the input power connector 51. The frequency converter 60 can convert the alternating current input from the input power connector 51 into an alternating current having a voltage and frequency suitable for driving the compressor motor 28. The frequency can be selected, for example, within the range from 30 Hz to 78 Hz. The rotational speed of the compressor motor 28 can be adjusted using the frequency converter 60, thereby improving the energy saving performance of the compressor 12.

[0073] To reduce the high-frequency noise of the frequency converter 60, the noise filter 64 can be connected to the frequency converter 60. The noise filter 64 is connected between the input power connector 51 and the frequency converter 60. Also, to suppress the harmonic current of the frequency converter 60, the DC reactor 66 can be connected to the frequency converter 60.

[0074] Transformer 62 converts the alternating current input from an external power source into the driving power source for the cold head 14. As described above, the cold head 14 is connected to the cold head connector 53. Depending on the country or region where the ultra-low temperature refrigerator is used, the alternating current input into the compressor 12 can have different voltages (for example, any one of a plurality of voltage values in the range of 380V to 480V). The transformer 62 can convert the alternating current input into the transformer 62 from the input power connector 51 into an alternating current with a voltage (such as 200V) suitable for driving the cold head 14. The transformer 62 is also known as a voltage conversion transformer. By incorporating the transformer 62, the compressor 12 can be used as the power source for the cold head 14. Also, the transformer 62 helps to insulate the cold head 14 from power supply noise.

[0075] The switching power supply 68 converts the alternating current input from an external power source into direct current. As Figure 5 shown, the switching power supply 68 can be connected between the transformer 62 and the controller 70. The switching power supply 68 can convert the alternating current output from the transformer 62 into direct current and supply this direct current to the controller 70.

[0076] In this embodiment, the switching power supply 68 and the transformer 62 are separately provided. Alternating current is output from the transformer 62, and direct current is output from the switching power supply 68. The switching power supply 68 can be arranged separately from the transformer 62 on the control panel 50. Therefore, compared with the case of using a transformer that can output both alternating current and direct current, the transformer 62 can ensure an insulation distance inside, thereby improving the insulation performance.

[0077] The controller 70 can receive the outputs from various sensors such as the above-mentioned pressure sensor and temperature sensor provided on the ultra-low temperature refrigerator 10, and control the frequency converter 60 according to the sensor outputs.

[0078] Figure 6 is a diagram schematically showing the appearance of the compressor unit of the ultra-low temperature refrigerator according to the embodiment. In Figure 6 the side panel 24f of the compressor unit housing 24 is shown. And, for ease of understanding, in Figure 6 the control panel 50 arranged inside the side panel 24f is shown by a dashed line.

[0079] As Figure 6As shown, the compressor unit housing 24 has a housing air inlet 72 and a housing air outlet 74. The housing air inlet 72 is an inlet for the cooling air leading from the surrounding environment to the compressor 12, and the housing air outlet 74 is an outlet for the cooling air leading from the compressor 12 to the surrounding environment. The components of the compressor 12 housed in the compressor unit housing 24 are cooled by the air entering the compressor unit housing 24 from the housing air inlet 72. The air heated by cooling the compressor 12 is discharged to the outside of the compressor 12 from the housing air outlet 74.

[0080] The housing air inlet 72 is disposed at a position lower than the housing air outlet 74. Therefore, the natural convection of the air heated as the compressor 12 is cooled can be utilized to generate an air flow from the housing air inlet 72 to the housing air outlet 74, thereby effectively cooling the compressor 12. In this example, the housing air inlet 72 and the housing air outlet 74 are provided on the side panel 24f of the compressor unit housing 24. The housing air inlet 72 and the housing air outlet 74 are disposed close to the front panel 24a on the side panel 24f.

[0081] The housing air inlet 72 is formed in the lower part of the side panel 24f, and the housing air outlet 74 is formed in the upper part of the side panel 24f. As described above, the control panel 50 is disposed adjacent to the side panel 24f in the compressor unit housing 24. Therefore, the housing air inlet 72 is adjacent to the lower part of the control panel 50, and the housing air outlet 74 is adjacent to the upper part of the control panel 50.

[0082] Figure 7 It is a diagram schematically showing the equipment arrangement on the control panel of the compressor unit according to the embodiment. In Figure 7 is shown the arrangement of the equipment on the control panel 50 when observing the control panel 50 from the front in a state where the front panel 24a is removed from the compressor unit housing 24, and for the sake of easy understanding, the flow of the cooling air is shown by arrows.

[0083] As described above, the frequency converter 60, the transformer 62, the noise filter 64, the DC reactor 66, the switching power supply 68, and the controller 70 are mounted on the control panel 50.

[0084] In this embodiment, the transformer 62 is arranged at a position lower than the frequency converter 60. The noise filter 64 and the DC reactor 66 are arranged at a position lower than the frequency converter 60 and higher than the transformer 62. Therefore, among the frequency converter 60, the transformer 62, the noise filter 64, and the DC reactor 66, the frequency converter 60 is arranged at the highest position on the control panel 50. Among the frequency converter 60, the transformer 62, the noise filter 64, and the DC reactor 66, the transformer 62 is arranged at the lowest position on the control panel 50. The switching power supply 68 and the controller 70 are arranged beside the frequency converter 60, that is, at the same height as the frequency converter 60.

[0085] The frequency converter 60 includes a frequency converter housing 60a and a frequency converter circuit 60b, and the frequency converter circuit 60b is accommodated in the frequency converter housing 60a. The frequency converter circuit 60b operates in a manner of converting the alternating current input from an external power supply to the compressor 12 into the drive power supply for the compressor motor 28.

[0086] The frequency converter housing 60a has a frequency converter air inlet 76 and a frequency converter air outlet 78. The frequency converter air inlet 76 is the inlet of the cooling air leading from the control panel 50 to the frequency converter 60, and the frequency converter air outlet 78 is the outlet of the cooling air leading from the frequency converter 60 to the control panel 50.

[0087] The frequency converter air inlet 76 is arranged at a position lower than the frequency converter air outlet 78. As shown in the attached drawings, the frequency converter air inlet 76 is provided at the lower part of the frequency converter housing 60a, and the frequency converter air outlet 78 is provided at the upper part of the frequency converter housing 60a. Therefore, the frequency converter air inlet 76 is located at a position higher than the transformer 62, the noise filter 64, and the DC reactor 66. The frequency converter air outlet 78 is located at a position higher than the transformer 62, the noise filter 64, the DC reactor 66, the switching power supply 68, and the controller 70.

[0088] Moreover, the control panel 50 is provided with an exhaust passage 80 that delimits the flow path of the cooling air leading from the frequency converter air outlet 78 to the housing exhaust port 74. The exhaust passage 80 is mounted on the control panel 50 above the frequency converter 60. Therefore, the exhaust passage 80 is arranged at the top of the control panel 50. The exhaust passage 80 has a passage inlet adjacent to the frequency converter air outlet 78 and a passage outlet adjacent to the housing exhaust port 74.

[0089] As described above, the housing air inlet 72 is arranged at a position lower than the housing exhaust port 74, and the transformer 62 is arranged at a position lower than the frequency converter 60. Therefore, compared with the transformer 62, the frequency converter 60 is arranged closer to the housing exhaust port 74. Compared with the frequency converter 60, the transformer 62 is arranged closer to the housing air inlet 72. The housing air inlet 72 is adjacent to the transformer 62 arranged at the lower part of the control panel 50.

[0090] Therefore, as shown by the dashed arrow in Figure 7 Cooling air enters the control panel 50 within the compressor unit housing 24 from the outside of the compressor 12 through the housing air inlet 72 and first cools the transformer 62. The air that has cooled the transformer 62 rises within the control panel 50, thereby cooling the noise filter 64 and the DC reactor 66. Further, the cooling air rises further and enters the inverter housing 60a through the inverter air inlet 76, thereby cooling the inverter circuit 60b. In this way, the air that has cooled the inverter 60 flows out of the inverter housing 60a from the inverter exhaust port 78 and flows into the exhaust passage 80 from the passage inlet. Within the exhaust passage 80, the flow of the air is guided to the passage outlet and is discharged to the outside of the compressor 12 through the housing exhaust port 74 through the passage outlet.

[0091] In this embodiment, compared with the devices on the control panel 50 such as the transformer 62, the noise filter 64, the DC reactor 66, the switching power supply 68, and the controller 70, the inverter 60 generates a relatively large amount of heat during operation. The air that passes through the inverter 60 and has cooled the inverter 60 may become as high as 50°C, for example. When the high-temperature air output from the inverter 60 comes into contact with other devices, it may not cool the device but instead heat the device. However, according to the embodiment, the inverter 60 is arranged at the most downstream of the cooling air flow, and the air that has cooled the inverter 60 is directly discharged to the outside of the compressor 12 from the housing exhaust port 74. Therefore, it is possible to avoid the following problem: the high-temperature air output from the inverter 60 may interfere with the cooling of other devices.

[0092] Moreover, since the exhaust passage 80 delimits the flow path of the cooling air from the inverter exhaust port 78 to the housing exhaust port 74, the air from the inverter 60 is guided to the outside of the compressor 12 through the exhaust passage 80. The exhaust passage 80 helps to prevent the high-temperature air output from the inverter 60 from leaking into the control panel 50.

[0093] Assume that the heat generation amount of the transformer 62 is second only to that of the inverter 60. The transformer 62 is adjacent to the housing air inlet 72, so it can be effectively cooled by the fresh air from the housing air inlet 72. And since the transformer 62 is heavy, by arranging it below the control panel 50, the center of gravity of the compressor 12 can be lowered, thereby improving stability.

[0094] In this embodiment, the occupied space of the compressor 12 falls within a region with a width of 600 mm or less and a length of 500 mm or less. Here, as Figure 2As shown, the width of the occupied space of the compressor 12 corresponds to the width W of the compressor unit housing 24. The length of the occupied space of the compressor 12 corresponds to the length L of the compressor unit housing 24. In this way, the occupied space of the compressor 12 can be made the same as that of a conventional compressor for an ultra-low temperature refrigerator.

[0095] Moreover, the height H of the compressor 12 can also be 700 mm or less. In this way, when the heat exchanger 22 of the compressor 12 is water-cooled, the height H of the compressor 12 can be made the same as that of a conventional compressor for an ultra-low temperature refrigerator.

[0096] The present invention has been described based on the embodiments. Those skilled in the art should understand that the present invention is not limited to the above-described embodiments, and various design changes and various variations can be made, and such variations are also within the scope of the present invention. The various features described in one embodiment can also be applied to other embodiments. The new embodiments generated by combination have the effects of the combined embodiments.

[0097] In the above embodiment, the case where the compressor 12 has a water-cooled heat exchanger 22 has been described as an example. However, as Figure 8 shown, the compressor 12 can also be provided with an air-cooled heat exchanger 90 together with the water-cooled heat exchanger 22 or instead of the water-cooled heat exchanger 22. The air-cooled heat exchanger 90 can be provided on the compressor unit housing 24. At this time, the height H of the compressor 12 can be 1000 mm or less. In this way, the height H of the compressor 12 can be made the same as that of a conventional compressor for an ultra-low temperature refrigerator.

[0098] Figure 9 is a diagram showing the equipment arrangement on the control panel 50 of the compressor unit according to the embodiment. In Figure 9 shows Figure 7 the schematic internal structure of the frequency converter 60 and the exhaust passage 80 on the control panel 50 shown in

[0099] In order to effectively cool the frequency converter 60, an air-cooling fan 60c can be provided on the control panel 50. The air-cooling fan 60c is mounted on the frequency converter 60 so as to generate an air flow for cooling the frequency converter circuit 60b within the frequency converter housing 60a. For the sake of easy understanding, similar to Figure 7 the same, in Figure 9 the flow of the cooling air in the exhaust passage 80 is also indicated by an arrow.

[0100] The air-cooled fan 60c can be disposed adjacent to the inverter exhaust port 78 within the inverter housing 60a. For example, it can be disposed between the inverter circuit 60b and the inverter exhaust port 78 of the inverter housing 60a. Alternatively, the air-cooled fan 60c can also be installed on the outer surface of the inverter housing 60a so as to be disposed between the inverter exhaust port 78 and the exhaust passage 80. The air-cooled fan 60c can also be a unit that is detachable from the inverter 60.

[0101] In Figure 7 and Figure 9 example, the exhaust passage 80 is a single passage component. As described above, the exhaust passage 80 is installed on the inverter housing 60a such that its inlet side is adjacent to the inverter exhaust port 78. And, the exhaust passage 80 is installed on the side panel 24f such that its outlet side is adjacent to the housing exhaust port 74. Thus, the inverter exhaust port 78 is connected to the housing exhaust port 74 through the exhaust passage 80, and the air that has cooled the inverter 60 is discharged to the outside of the compressor 12 through the exhaust passage 80 and then through the housing exhaust port 74.

[0102] To prevent the high-temperature exhaust gas coming out of the inverter exhaust port 74 from leaking into the control panel 50, the inlet of the exhaust passage 80 can be closely attached to the inverter housing 60a. For example, the inlet of the exhaust passage 80 can be installed on the inverter housing 60a by screw fixation. Alternatively, the inlet of the exhaust passage 80 can also be installed on the inverter housing 60a by an adhesive tape such as aluminum tape. Or, a sealing material such as a rubber material can be clamped between the inlet of the exhaust passage 80 and the inverter housing 60a. Similarly, to prevent the high-temperature exhaust gas coming out of the outlet of the exhaust passage 80 from leaking into the control panel 50, the outlet of the exhaust passage 80 can be closely attached to the side panel 24f. For example, the outlet of the exhaust passage 80 can be installed on the side panel 24f by screw fixation.

[0103] Among the various devices mounted on the control panel 50, the air-cooled fan 60c is more likely to have problems such as unstable rotation of the drive motor that occur over long-term use compared to other electrical components. In the event of a failure, maintenance work such as replacement or repair of the air-cooled fan 60c is carried out. Typically, the frame panels such as the side panel 24f that make up the compressor unit frame 24 have a folded portion 82 at at least one edge (the upper edge in the illustrated example) of the panel in order to improve structural strength or for installation on other panels. The folded portion 82 is provided above the installation portion of the exhaust passage 80 on the side panel 24f like an eaves that covers and hides the installation portion.

[0104] When wanting to access the air-cooled fan 60c for maintenance, first, the top panel 24c needs to be removed and the exhaust passage 80 taken out. However, if the outlet of the exhaust passage 80 is covered and hidden by the bent portion 82, it will be difficult for the operator to access the installation part even after removing the top panel 24c, and it will be difficult to release the installation of the exhaust passage 80 with respect to the side panel 24f. Also, even if trying to take out the exhaust passage 80 upward, the outlet of the exhaust passage 80 will interfere with the bent portion 82, and it may be impossible to take out the exhaust passage 80. When various components are densely arranged within the compressor unit housing 24, not only will it interfere with the bent portion 82, but also with these components, making the removal of the exhaust passage 80 even more difficult.

[0105] To address this problem, a solution can be considered where after removing the control panel 50 itself from the compressor unit housing 24, the exhaust passage 80 is removed from the control panel 50 to access the air-cooled fan 60c. However, such a large-scale disassembly operation of the compressor 12 will make the maintenance work complicated and increase the working hours, so it is not preferred.

[0106] Therefore, as described below, in order to improve maintainability, the exhaust passage 80 can be composed of multiple channel components.

[0107] Figure 10 It is a diagram schematically showing another example of the exhaust passage 80 mounted on the control panel 50 according to the embodiment. The exhaust passage 80 includes a channel inlet component 80a and a channel outlet component 80b. The channel inlet component 80a is mounted adjacent to the inverter exhaust port 78 on the inverter housing 60a. The channel inlet component 80a can be removed from the channel outlet component 80b and the inverter 60. For example, the channel inlet component 80a can be detachably mounted to the channel outlet component 80b by screw fixation. The channel outlet component 80b is mounted adjacent to the housing exhaust port 74 on the side panel 24g.

[0108] The channel inlet component 80a can be a cover that covers the end of the channel outlet component 80b on the side opposite to the housing exhaust port 74 and the inverter exhaust port 78. By Figure 9 and Figure 10 comparison, it can be seen that the length of the channel inlet component 80a in the channel length direction is shorter than that of Figure 9 the exhaust passage 80 (a single channel component). Here, the channel length direction refers to the extending direction of the exhaust passage 80 (the left-right direction in the figure). The channel length direction corresponds to the extending direction of the bent portion 82 of the side panel 24f.

[0109] The length of the channel inlet member 80a in the channel length direction is determined as follows: when the channel inlet member 80a is installed on the channel outlet member 80b, the end of the channel inlet member 80a on the channel outlet member 80b side does not overlap with the bending portion 82. That is, the channel inlet member 80a is not covered and hidden by the bending portion 82.

[0110] The channel outlet member 80b can be a (e.g., rectangular) cylinder extending from the side panel 24f in the channel length direction. The length of the channel outlet member 80b in this direction is shorter than Figure 9 that of the exhaust channel 80 (a single channel member). To facilitate the installation of the channel inlet member 80a on the channel outlet member 80b and the removal of the channel inlet member 80a from the channel outlet member 80b, as shown in the figure, the length of the channel outlet member 80b can be longer than the length of the bending portion 82. Also, to prevent the channel outlet member 80b from blocking the inverter exhaust port 78, the length of the channel outlet member 80b can be determined not to overlap with the inverter exhaust port 78.

[0111] Thus, the inverter exhaust port 78 is connected to the cabinet exhaust port 74 through the channel inlet member 80a and the channel outlet member 80b, and the air that has cooled the inverter 60 is discharged from the cabinet exhaust port 74 to the outside of the compressor through the exhaust channel 80. In Figure 10 the example shown, as in Figure 9 the example shown, to prevent the high-temperature exhaust gas coming out of the inverter exhaust port 78 from leaking into the control panel 50, the channel inlet member 80a can be closely attached to the inverter cabinet 60. Also, the channel outlet member 80b can be closely attached to the side panel 24f.

[0112] To perform maintenance on the air-cooling fan 60c, first remove the top panel 24c. Then remove the channel inlet member 80a from the channel outlet member 80b and the inverter 60. Different from Figure 9 the example of Figure 10 the example shown, in Figure 10 the example shown, the channel inlet member 80a is not covered and hidden by the bending portion 80. Thus, as shown by the upward arrow in Figure 9 it, the channel inlet member 80a can be taken out upward without interfering with the bending portion 82. In this way, it is easier to take out the channel inlet member 80a than

[0113] In the above-described embodiment, the case where the casing air inlet 72 and the casing air outlet 74 are provided on the side panel 24f of the compressor unit casing 24 has been illustrated. However, the casing air inlet 72 and the casing air outlet 74 may also be provided on other panels of the compressor unit casing 24. For example, the casing air inlet 72 and the casing air outlet 74 may also be provided on the front panel 24a. At this time, similarly to the above-described embodiment, the control panel 50 may also include an exhaust passage 80 that defines a flow path of the cooling air leading from the inverter air outlet 78 to the casing air outlet 74. The exhaust passage 80 may be a single passage member, or may include a plurality of passage members.

[0114] As described above, the present invention has been described based on the embodiments using specific terms. However, the embodiments only show one aspect of the principle and application of the present invention. In the embodiments, various modifications and changes in configuration are allowed within the scope not departing from the idea of the present invention defined in the technical solution.

Claims

1. A compressor unit, which is a compressor unit of an ultra-low temperature refrigerator, characterized in that, Comprising: A compressor motor; An inverter that converts alternating current input from an external power source into a driving power source for the compressor motor; A transformer that converts the alternating current into a driving power source for the cold head of the ultra-low temperature refrigerator having a voltage different from that of the alternating current; And A control panel on which the inverter and the transformer are mounted.

2. The compressor unit according to claim 1, wherein The inverter has an inverter exhaust port that serves as an outlet for cooling air from the inverter, and the inverter is mounted on the control panel such that the inverter exhaust port is located above the transformer.

3. The compressor unit according to claim 1, wherein The transformer is arranged at a position lower than the inverter.

4. The compressor unit according to any one of claims 1 to 3, wherein It further comprises a switching power supply that converts the alternating current into direct current, The switching power supply is mounted on the control panel.

5. The compressor unit according to claim 4, wherein The inverter has an inverter exhaust port that serves as an outlet for cooling air from the inverter, and the inverter is mounted on the control panel such that the inverter exhaust port is located above the switching power supply.

6. The compressor unit according to any one of claims 1 to 3, wherein It further comprises a noise filter and a DC reactor, the noise filter and the DC reactor are connected to the inverter, The noise filter and the DC reactor are mounted on the control panel.

7. The compressor unit according to claim 6, wherein The inverter has an inverter exhaust port that serves as an outlet for cooling air from the inverter, and the inverter is mounted on the control panel such that the inverter exhaust port is located above the noise filter and the DC reactor.

8. The compressor unit according to claim 6, wherein The noise filter and the DC reactor are arranged at a position lower than the inverter and higher than the transformer.

9. The compressor unit according to any one of claims 1 to 3, wherein The inverter has an inverter exhaust port that serves as an outlet for cooling air from the inverter, The compressor unit further comprises a compressor unit housing that has a housing exhaust port that serves as an outlet for the cooling air from the compressor unit and houses the compressor motor and the control panel, The control panel is provided with an exhaust passage that delimits a flow path of the cooling air from the inverter exhaust port to the housing exhaust port.

10. The compressor unit according to claim 9, wherein The compressor unit housing has a housing air inlet, which is arranged at a position lower than the housing air outlet and serves as the inlet of the cooling air leading to the compressor unit.

11. The compressor unit according to claim 10, wherein compared with the transformer, the frequency converter is arranged closer to the housing air outlet, compared with the frequency converter, the transformer is arranged closer to the housing air inlet.

12. The compressor unit according to claim 9, wherein the exhaust passage includes a passage inlet component adjacent to the frequency converter exhaust port and a passage outlet component adjacent to the housing air outlet, and the passage inlet component can be detached from the passage outlet component and the frequency converter.

13. The compressor unit according to any one of claims 1 to 3, wherein the occupied space of the compressor unit falls within a region with a width of 600 mm or less and a length of 500 mm or less.

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