Cryogenic cooling devices and superconducting devices

Abstract

To reduce a heat load exerted on a cooling source and cool an object to be cooled (a cooled object) efficiently.SOLUTION: A cryogenic cooling device has: a gas pipe 12 which is provided over both a room temperature region N and a low temperature region M and enables a cooled object 1 to be disposed in the low temperature region; a compressor 13 disposed in the room temperature region and configured to circulate a cooling gas X in the gas pipe; a heat exchanger 14 which is disposed in the low temperature region and configured to conduct heat exchange of a high pressure side cooling gas from the compressor with a low pressure side cooling gas returning to the compressor to cool the high pressure side cooling gas; a refrigeration machine 15 disposed in the low temperature region and configured to cool the cooling gas and cool the cooled object by the cooling gas; and an ejector 16 disposed in the low temperature region and serving as a pump function of the cooling gas. In the ejector, a driving port 19 is connected to a high pressure side outlet of the heat exchanger through the gas pipe and the gas pipe connected to a discharge port 23 is branched. One branched gas pipe 12A is connected to a low pressure side inlet of the heat exchanger and the other branched gas pipe 12B is connected to a suction port 21 of the ejector after sequentially passing the refrigeration machine and the cooled object.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a cryogenic cooling device using a gas circulation cooling method for cooling an object to be cooled with a cooling gas, and a superconducting device including the cryogenic cooling device.

Background Art

[0002] As a cryogenic cooling device for cooling a superconducting coil to a cryogenic temperature, there is a conduction cooling method using a refrigerator (cryogenic refrigerator). This conduction cooling method has advantages such as not requiring the handling of liquid helium, which requires specialized knowledge, and not being affected by the difficulty of obtaining liquid helium due to the depletion problem of helium resources in recent years compared to the method of cooling with liquid helium. However, when the refrigerator cannot be used in a magnetic field and needs to be separated from the superconducting coil, or when cooling a plurality of objects to be cooled with one refrigerator, the heat transfer distance between the refrigerator and the superconducting coil becomes long. Therefore, in the conduction cooling method, there is a problem that the temperature difference between the refrigerator and the superconducting coil becomes large.

[0003] Therefore, a cryogenic cooling device using a gas circulation cooling method in which a cooling gas cooled by a refrigerator is circulated for cooling is advantageous. In this gas circulation cooling method, there is an advantage that the temperature difference between the refrigerator and the superconducting coil does not increase even when the distance between them is increased.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a conventional cryogenic cooling system 100, as shown in Figure 13(A), a compressor 102 that circulates cooling gas Z in a gas pipe 101 is installed in the room temperature region V outside the vacuum insulated container 104. A heat exchanger 103 connected to the high-pressure and low-pressure sides of this compressor 102 cools the high-pressure cooling gas Z flowing into the low-temperature region U inside the vacuum insulated container 104 by heat exchange with the low-pressure cooling gas Z returning to the compressor 102. The gas pipe 101 connected to the high-pressure outlet of the heat exchanger 103 is then connected to the low-pressure inlet of the heat exchanger 103 after the refrigerator (cryogenic refrigerator) 105 and the object to be cooled 106 have been sequentially installed, forming a circulation loop for the cooling gas Z.

[0006] In other conventional cryogenic cooling devices 110, as shown in Figure 13(B), a cryogenic fan 111 circulates a cooling gas Z in a low-temperature region U within a vacuum-insulated container 104. A gas pipe 112 connected to the high-pressure outlet of this cryogenic fan 111 is connected to the low-pressure inlet of the cryogenic fan 111 after the refrigerator (cryogenic refrigerator) 105 and the object to be cooled 106 have been installed, forming a circulation loop for the cooling gas Z.

[0007] In the conventional cryogenic cooling device 100 shown in Figure 13(A), the object to be cooled 106, such as a superconducting coil, is cooled to an extremely low temperature by the refrigerator 105 absorbing the heat load, which is the sum of the heat generated by the superconducting coil and the heat that enters through radiation from the room temperature region V and heat conduction through the support members. However, in the heat exchanger 103, when the cooling gas Z from the room temperature region V flows into the low-temperature region U, an additional heat load is generated due to the loss of heat exchange between the cooling gas Z returning to the room temperature region V and the cooling gas Z, causing the temperature of the object to be cooled 106 to rise.

[0008] In particular, when cooling a superconducting coil, which has a large thermal load, as the object to be cooled 106, the temperature difference between the cooling gas Z at the inlet and outlet of the object to be cooled 106 can be reduced by increasing the gas flow rate of the cooling gas Z. However, in this case, a large amount of cooling gas Z flows in from the room temperature range V, increasing the thermal load on the refrigerator 105. Therefore, in order to cool the object to be cooled 106 to below the desired temperature, it becomes necessary to improve the cooling capacity of the refrigerator 105, which, for example, increases the number of refrigerators 105 required.

[0009] Furthermore, in other conventional cryogenic cooling devices 110 shown in Figure 13(B), a mechanical connection is required in the room temperature region V to drive the low-temperature fan 111 located in the low-temperature region U. As a result, heat intrusion occurs through heat conduction from the mechanical connection in the room temperature region V, and this adds a heat load to the refrigerator 105, causing the temperature of the object being cooled 106 to rise. In particular, if the object being cooled 106 is a superconducting coil with a large heat load, it is necessary to increase the power of the low-temperature fan 111 in order to increase the flow rate of the cooling gas Z. Consequently, the mechanical connection becomes larger, and the amount of heat intrusion from the low-temperature region U into the cooling gas Z via the low-temperature fan 111 increases.

[0010] In the conventional cryogenic cooling devices 100 and 110 shown in Figures 13(A) and (B), the challenge is to suppress the additional heat load on the refrigerator 105 as described above and to suppress the temperature rise of the object to be cooled 106.

[0011] Furthermore, in the invention described in Patent Document 1, the ejector is used to circulate the cooling gas in the low-temperature region, reduce the flow rate of the cooling gas flowing in from the room-temperature region, and thereby reduce the amount of heat entering the low-temperature region. In this invention, the high-pressure cooling gas from the heat exchanger is supplied to the suction port of the ejector, not the drive port. The characteristic of the ejector is its pump function, which increases the pressure of the low-pressure suction gas at the nozzle and discharges it. However, in the invention described in Patent Document 1, because the pressure of the suction gas is high, the above-mentioned characteristic of the ejector (pump function) cannot be fully utilized, the pressure difference between the drive port and the discharge port of the ejector becomes small, and the flow rate of the cooling gas circulating in the low-temperature region is small.

[0012] The embodiments of the present invention have been made in consideration of the above circumstances, and aim to provide a cryogenic cooling device and a superconducting device that can efficiently cool an object to be cooled by reducing the heat load on the cooling source. [Means for solving the problem]

[0013] The cryogenic cooling apparatus in the embodiment of the present invention is provided across both a room temperature region and a low temperature region partitioned by an insulated container, and includes a gas pipe through which an object to be cooled is placed in the low temperature region, a compressor disposed in the gas pipe within the room temperature region for circulating cooling gas within the gas pipe, a heat exchanger disposed in the gas pipe within the low temperature region for cooling the high-pressure cooling gas from the compressor by heat exchange with the low-pressure cooling gas returning to the compressor, and a device disposed upstream of the object to be cooled in the gas pipe within the low temperature region for cooling the cooling gas. The system comprises a cooling source that cools the object to be cooled with the cooling gas, and an ejector disposed between the heat exchanger and the cooling source in the gas piping within the low-temperature region, which performs a pump function for the cooling gas. The ejector is configured such that its drive port is connected to the high-pressure side outlet of the heat exchanger via the gas piping, the gas piping connected to the discharge port is branched, one branch gas piping is connected to the low-pressure side inlet of the heat exchanger, and the other branch gas piping is connected to the suction port of the ejector after the cooling source and the object to be cooled are sequentially arranged. Furthermore, the system comprises a valve disposed in one of the branch gas pipes in the gas piping connected to the discharge port of the ejector, a sensor for measuring the state of the object to be cooled or the state of the cooling gas within the object to be cooled, and a monitoring device that adjusts the opening of the valve based on the measurement value from the sensor to control the system in order to suppress the temperature rise of the object to be cooled. It is characterized by the following.

[0014] Furthermore, the cryogenic cooling device in the embodiment of the present invention is provided in a low-temperature region surrounded by an insulated container and comprises: a gas pipe for arranging an object to be cooled; a low-temperature fan arranged in the gas pipe for circulating cooling gas within the gas pipe; a cooling source arranged upstream of the object to be cooled in the gas pipe for cooling the cooling gas and using this cooling gas to cool the object to be cooled; and an ejector arranged between the low-temperature fan and the cooling source in the gas pipe for pumping the cooling gas. The ejector is configured such that its drive port is connected to the high-pressure side outlet of the low-temperature fan via the gas pipe, the gas pipe connected to the discharge port is branched, one branched gas pipe is connected to the low-pressure side inlet of the low-temperature fan, and the other branched gas pipe is connected to the suction port of the ejector after the cooling source and the object to be cooled are arranged in sequence. Furthermore, the system comprises a valve disposed in one of the branch gas pipes in the gas piping connected to the discharge port of the ejector, a sensor for measuring the state of the object to be cooled or the state of the cooling gas within the object to be cooled, and a monitoring device that adjusts the opening of the valve based on the measurement value from the sensor to control the system in order to suppress the temperature rise of the object to be cooled. It is characterized by the following.

[0015] Furthermore, the superconducting device in the embodiment of the present invention is characterized by having a cryogenic cooling device as described in the embodiment, wherein the object to be cooled is a superconducting coil. [Effects of the Invention]

[0016] According to embodiments of the present invention, the heat load on the cooling source can be reduced, and the object to be cooled can be cooled efficiently. [Brief explanation of the drawing]

[0017] [Figure 1] A piping diagram showing the configuration of the cryogenic cooling device according to the first embodiment. [Figure 2] A diagram showing the ejector configuration in Figure 1. [Figure 3] A piping diagram showing the configuration of the cryogenic cooling system according to the second embodiment. [Figure 4] A piping diagram showing the configuration of the cryogenic cooling system according to the third embodiment. [Figure 5] A piping diagram showing the configuration of the cryogenic cooling system according to the fourth embodiment. [Figure 6] Figure 5 shows a piping diagram illustrating the configuration of a deformed form in a cryogenic cooling device. [Figure 7] Pipeline diagram showing the configuration of the cryogenic cooling device according to the fifth embodiment. [Figure 8] Pipeline diagram showing the configuration of a modified form in the cryogenic cooling device of FIG. 7. [Figure 9] Pipeline diagram showing the configuration of the cryogenic cooling device according to the sixth embodiment. [Figure 10] Pipeline diagram showing the configuration of a modified form in the cryogenic cooling device of FIG. 9. [Figure 11] Pipeline diagram showing the configuration of the cryogenic cooling device according to the seventh embodiment. [Figure 12] Pipeline diagram showing the configuration of a modified form in the cryogenic cooling device of FIG. 11. [Figure 13] (A) is a pipeline diagram showing a conventional cryogenic cooling device, and (B) is a pipeline diagram showing another conventional cryogenic cooling device.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments for carrying out the present invention will be described based on the drawings. [A] First Embodiment (FIGS. 1 and 2) FIG. 1 is a pipeline diagram showing the configuration of the cryogenic cooling device according to the first embodiment. The cryogenic cooling device 10 shown in this FIG. 1 uses a superconducting coil that constitutes a superconducting device such as an MRI (Magnetic Resonance Imaging Diagnostic Device) as the object to be cooled 1, and cools this object to be cooled 1 to a cryogenic temperature (for example, about 4K to 10K) by a gas circulation cooling method. It is configured to include a vacuum heat insulation container 11, a gas pipe 12, a compressor 13, a heat exchanger 14, a refrigerator (cryogenic refrigerator) 15 as a cooling source, and an ejector 16.

[0019] The vacuum heat insulation container 11 partitions the inner low-temperature region M and the outer room-temperature region N, and maintains the low-temperature region M at a cryogenic temperature of, for example, about 4K to 10K by a heat insulation function.

[0020] The gas piping 12 is provided across both the low-temperature region M and the room-temperature region N. A compressor 13 is located in the gas piping 12 provided in the room-temperature region N, while a heat exchanger 14, a cooling stage 15A of the chiller 15, and an ejector 16 are located in the gas piping 12 provided in the low-temperature region M. Furthermore, the gas piping 12 forms a first circulation loop 17 that circulates the cooling gas X between the compressor 13, the heat exchanger 14, and the ejector 16, and a second circulation loop 18 that circulates the cooling gas X between the ejector 16, the cooling stage 15A of the chiller 15, and the object to be cooled 1.

[0021] The compressor 13 is located in the gas piping 12 within the room temperature region N and circulates the cooling gas X within the gas piping 12 of the first circulation loop 17. The heat exchanger 14 is located in the gas piping 12 within the low temperature region M and cools the high-pressure cooling gas X from the compressor 13 by heat exchange with the low-pressure cooling gas X returning to the compressor 13.

[0022] The chiller 15 is installed in the vacuum-insulated container 11, and the cooling stage 15A is positioned upstream of the object to be cooled 1 in the gas piping 12 within the low-temperature region M. The cooling stage 15A of the chiller 15 cools the cooling gas X in the gas piping 12 of the second circulation loop 18, and this cooling gas X cools the object to be cooled 1 downstream of the cooling stage 15A.

[0023] The ejector 16 is positioned between the heat exchanger 14 and the cooling stage 15A of the chiller 15 in the gas piping 12 in the low-temperature region M, and performs a pump function for the cooling gas X. That is, as shown in Figures 1 and 2, the drive port 19 of the ejector 16 is connected to the high-pressure side outlet of the heat exchanger 14 via the gas piping 12. The gas piping 12 connected to the discharge port 23 of the ejector 16 is branched, with one branch gas piping 12A connected to the low-pressure side inlet of the heat exchanger 14, and the other branch gas piping 12B connected to the suction port 21 of the ejector 16 after the cooling stage 15A of the chiller 15 and the object to be cooled 1 have been sequentially arranged.

[0024] Accordingly, the ejector 16 injects the high-pressure cooling gas X from the heat exchanger 14 as the drive gas A through the drive port 19, depressurizes and accelerates it in the nozzle 20, and uses the kinetic energy of this drive gas A to draw in the low-pressure cooling gas X, which has cooled the object to be cooled 1, as the suction gas B through the suction port 21. These drive gas A and suction gas B are mixed, and this mixed gas is pressurized and decelerated in the diffuser 22 and discharged as discharge gas C from the discharge port 23. In this way, the ejector 16 has a pump function as it draws in the low-pressure cooling gas X from the suction port 21, pressurizes it, and discharges it from the discharge port 23.

[0025] Here, the pressure of the cooling gas X that is drawn into the inlet 21 of the ejector 16 after the object to be cooled 1 is set to be above the critical pressure of the cooling gas X. As a result, the cooling gas X flowing through the gas piping 12 of the cryogenic cooling device 10, the compressor 13, the heat exchanger 14, the ejector 16, the cooling stage 15A of the refrigerator 15, and inside the object to be cooled 1 is in a single-phase gaseous flow.

[0026] In the cryogenic cooling device 10 described above, the high-pressure cooling gas X compressed by the compressor 13 is cooled in the heat exchanger 14 by the cooling gas X returning to the compressor 13, then injected into the ejector 16 as drive gas A from the drive port 19 of the ejector 16, discharged as discharge gas C from the discharge port 23 of the ejector 16, returned to the compressor 13 via one branch gas pipe 12A and the heat exchanger 14, and circulates within the first circulation loop 17. In addition, the cooling gas X discharged as discharge gas C from the discharge port 23 of the ejector 16 and diverted to the other branch gas pipe 12B is cooled in the cooling stage 15A of the chiller 15, then cools the object to be cooled 1, and is drawn into the ejector 16 from the suction port 21 of the ejector 16, and circulates within the second circulation loop 18 by the pump function of the ejector 16.

[0027] As configured as described above, this first embodiment provides the following effects (1) and (2). (1) The ejector 16 performs a pump function by injecting high-pressure cooling gas X from the compressor 13 and heat exchanger 14 as drive gas A through the drive port 19, depressurizing and accelerating it with the nozzle 20 to draw in the low-pressure cooling gas X after it has cooled the object to be cooled 1 through the suction port 21 as suction gas B, mixing it with drive gas A, and then pressurizing and decelerating this mixed gas with the diffuser 22 before discharging it from the discharge port 23.

[0028] The pumping function of the ejector 16 causes the gas flow rate of the cooling gas X circulating in the second circulation loop 18 of the low-temperature region M, which includes the cooling stage 15A of the refrigerator 15, the object to be cooled 1, and the ejector 16, to be greater than the gas flow rate of the cooling gas X circulating in the first circulation loop 17 of the room-temperature region N, which includes the compressor 13. This is facilitated by the fact that the density of the cooling gas X flowing through the gas piping 12 in the low-temperature region M is high, and its pressure loss is small, as is the pressure loss of the cooling gas X flowing through the gas piping 12 in the room-temperature region N.

[0029] Therefore, the gas flow rate of the cooling gas X passing through the compressor 13 in the room temperature region N is less than the gas flow rate of the cooling gas X in the gas piping 12 in the low temperature region M that cools the object to be cooled 1. As a result, the heat load on the refrigerator 15 caused by the cooling gas X in the gas piping 12 in the room temperature region N flowing into the gas piping 12 in the low temperature region M can be reduced, and the object to be cooled 1 can be efficiently cooled by the cooling stage 15A of the refrigerator 15.

[0030] (2) Since the pressure of the cooling gas X on the low-pressure side returning from the object to be cooled 1 to the suction port 21 of the ejector 16 is set to be above the critical pressure of the cooling gas X, the cooling gas X flowing through the cryogenic cooling device 10 is a single-phase gas flow. Consequently, the cooling gas X in the ejector 16 (drive gas A, suction gas B, discharge gas C) is also a single-phase gas flow, so compared to the case where the cooling gas X is a two-phase gas-liquid flow or a single-phase liquid flow, the loss when the drive gas A is accelerated in the nozzle 20 to draw in the suction gas B is small, the loss when the drive gas A and suction gas B are mixed is small, and the loss when the mixed gas of the drive gas A and suction gas B is pressurized and discharged from the discharge port 23 is also small.

[0031] From these considerations, the ejector 16 can increase the gas flow rate when circulating the cooling gas X within the second circulation loop 18, which includes the object to be cooled 1 and the refrigerator 15. This further reduces the gas flow rate of the cooling gas X flowing within the first circulation loop 17, which includes the compressor 13 in the room temperature region N. As a result, the heat load on the refrigerator 15 caused by the cooling gas X in the room temperature region N flowing into the gas piping 12 in the low temperature region M can be further reduced, allowing the refrigerator 15 to cool the object to be cooled 1 even more efficiently.

[0032] [B] Second embodiment (Figure 3) Figure 3 is a piping diagram showing the configuration of the cryogenic cooling device according to the second embodiment. In this second embodiment, parts that are the same as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their explanation is simplified or omitted.

[0033] The difference between the cryogenic cooling device 25 of this second embodiment and the first embodiment is that the cooling source is a liquid refrigerant tank 27 storing a liquid refrigerant 26, such as liquid helium, instead of a refrigerator 15. This cryogenic cooling device 25 also provides the same effects as effects (1) and (2) of the first embodiment, as well as the following effect (3).

[0034] (3) The gas flow rate of the cooling gas X passing through the compressor 13 in the room temperature region N is less than the gas flow rate of the cooling gas X flowing through the gas piping 12 in the low temperature region M that cools the object to be cooled 1. This reduces the heat load on the liquid refrigerant 26 caused by the cooling gas X in the gas piping 12 in the room temperature region N flowing into the gas piping 12 in the low temperature region M. As a result, the amount of evaporation of the liquid refrigerant 26 stored in the liquid refrigerant tank 27 can be reduced.

[0035] [C] Third embodiment (Figure 4) Figure 4 is a piping diagram showing the configuration of the cryogenic cooling apparatus according to the third embodiment. In this third embodiment, parts that are the same as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their explanation is simplified or omitted.

[0036] The difference between the cryogenic cooling device 30 of this third embodiment and the first embodiment is that the first circulation loop 17 of the gas piping 12, together with the second circulation loop 18, is provided in a low-temperature region M surrounded by a vacuum-insulated container 11, and instead of a compressor 13 and a heat exchanger 14, a low-temperature fan 31 is provided in the gas piping 12 of the first circulation loop 17 to circulate the cooling gas X within the gas piping 12 of the first circulation loop 17.

[0037] Furthermore, the ejector 16 is positioned between the low-temperature fan 31 and the cooling stage 15A of the chiller 15 in the gas piping 12, and its drive port 19 is connected to the high-pressure side outlet of the low-temperature fan 31. In addition, one branch gas pipe 12A of the gas piping 12, which is branched from the discharge port 23 of the ejector 16, is connected to the low-pressure side inlet of the low-temperature fan 31, and the other branch gas pipe 12B is connected to the suction port 21 of the ejector 16 after the cooling stage 15A of the chiller 15 and the object to be cooled 1 have been sequentially arranged. Note that the cooling source is not limited to the chiller 15, but may also be the liquid refrigerant tank 27 of the second embodiment.

[0038] In the cryogenic cooling device 30 described above, the high-pressure cooling gas X, pumped by the low-temperature fan 31, is injected into the ejector 16 as drive gas A from the drive port 19 of the ejector 16, discharged as discharge gas C from the discharge port 23 of the ejector 16, returned to the low-temperature fan 31 via one branch gas pipe 12A, and circulates within the first circulation loop 17. The cooling gas X discharged as discharge gas C from the discharge port 23 of the ejector 16 and diverted to the other branch gas pipe 12B is cooled by the cooling stage 15A of the refrigerator 15, then cools the object to be cooled 1, is drawn into the ejector 16 from the suction port 21 of the ejector 16, and circulates within the second circulation loop 18 by the pump function of the ejector 16.

[0039] As configured as described above, this third embodiment provides the following effects (4) and (5). (4) The ejector 16 performs a pump function by injecting high-pressure cooling gas X from the low-temperature fan 31 as drive gas A through the drive port 19, depressurizing and accelerating it with the nozzle 20 to obtain kinetic energy, drawing in the low-pressure cooling gas X after it has cooled the object to be cooled 1 through the intake port 21 and mixing it with drive gas A, and then pressurizing and decelerating this mixed gas with the diffuser 22 and discharging it from the discharge port 23.

[0040] The pump function of the ejector 16 causes the gas flow rate of the cooling gas X circulating in the first circulation loop 17 by the low-temperature fan 31 to be lower than the gas flow rate of the cooling gas X circulating in the second circulation loop 18, which includes the cooling stage 15A of the refrigerator 15, the object to be cooled 1, and the ejector 16. This makes it possible to reduce the power of the low-temperature fan 31, and the mechanical connection part in the room temperature range N for driving the low-temperature fan 31 can be made smaller. As a result, the heat load on the refrigerator 15 due to heat intrusion from this mechanical connection part can be reduced, so that the object to be cooled 1 can be cooled efficiently by the cooling stage 15A of the refrigerator 15.

[0041] (5) Since the pressure of the cooling gas X on the low-pressure side returning from the object to be cooled 1 to the suction port 21 of the ejector 16 is set to be above the critical pressure of the cooling gas X, the cooling gas X flowing through the cryogenic cooling device 30 is a single-phase gas flow. Consequently, the cooling gas X (drive gas A, suction gas B, discharge gas C) inside the ejector 16 (drive gas A, suction gas B, discharge gas C) is also a single-phase gas flow. Compared to the case where the cooling gas X is a two-phase gas-liquid flow or a single-phase liquid flow, the loss when the drive gas A is accelerated in the nozzle 20 to draw in the suction gas B is small, the loss when the drive gas A and suction gas B are mixed is small, and the loss when the mixed gas of the drive gas A and suction gas B is pressurized and discharged from the discharge port 23 is also small.

[0042] As a result, the gas flow rate when circulating the cooling gas X in the second circulation loop 18, which includes the object to be cooled 1 and the refrigerator 15, can be increased by the ejector 16, thereby further reducing the gas flow rate of the cooling gas X flowing in the first circulation loop 17, which includes the low-temperature fan 31. Therefore, the low-temperature fan 31 can be made smaller, and the amount of heat intrusion from the mechanical connection part in the room temperature region N of the low-temperature fan 31 can be reduced, thereby further reducing the heat load on the refrigerator 15. As a result, the object to be cooled 1 can be cooled even more efficiently by this refrigerator 15.

[0043] [D] Fourth embodiment (Figures 5 and 6) Figure 5 is a piping diagram showing the configuration of the cryogenic cooling apparatus according to the fourth embodiment. In this fourth embodiment, parts that are the same as those in the first to third embodiments are denoted by the same reference numerals as in the first to third embodiments, thereby simplifying or omitting their explanation.

[0044] The difference between the cryogenic cooling device 40 of this fourth embodiment and the first to third embodiments is that the vacuum insulated container has a first vacuum insulated container 41X (Figure 5) that houses the heat exchanger 14, the cooling stage 15A of the refrigerator 15 and the ejector 16, or a first vacuum insulated container 41Y (Figure 6) that houses the low-temperature fan 31, the cooling stage 15A of the refrigerator 15 and the ejector 16, and a second vacuum insulated container 42 that houses the object to be cooled 1. Furthermore, in this cryogenic cooling device 40, the gas piping 12 in the first vacuum insulated container 41X or 41Y and the second vacuum insulated container 42 are connected by an insulated gas piping 43 provided between the first vacuum insulated container 41X or 41Y and the second vacuum insulated container 42.

[0045] Here, the compressor 13 is located in the room temperature region N outside the first vacuum-insulated container 41X. Furthermore, the cooling source is not limited to the refrigerator 15, but may also be the liquid refrigerant tank 27 in the second embodiment.

[0046] In this cryogenic cooling device 40, the separation of the first vacuum insulated container 41X or 41Y, which houses the cooling stage 15A (or liquid refrigerant tank 27) of the refrigerator 15 and the ejector 16, and the second vacuum insulated container 42, which houses the object to be cooled 1, results in a longer gas piping 12 in the low-temperature region M provided within the first vacuum insulated containers 41X, 41Y and the second vacuum insulated container 42, increasing the pressure loss in this gas piping 12. In this case, by setting the outlet output of the compressor 13 or the low-temperature fan 31 to a higher value, it is possible to increase the kinetic energy of the cooling gas X injected from the nozzle 20 of the ejector 16. This increases the gas flow rate of the cooling gas X (discharge gas C) discharged from the discharge port 23 of the ejector 16, making it possible to cool the object to be cooled 1 effectively with this cooling gas X.

[0047] As configured as described above, the cryogenic cooling device 40 of this fourth embodiment provides the same effects as the first to third embodiments (1) to (5), as well as the following effect (6).

[0048] (6) Since the first vacuum insulated containers 41X, 41Y that house the cooling stage 15A (or liquid refrigerant tank 27) and ejector 16 of the refrigerator 15 and the second vacuum insulated container 42 that houses the object to be cooled 1 are configured separately, the refrigerator 15 can be separated from, for example, the superconducting coil of the object to be cooled 1. As a result, the refrigerator 15 can be operated without being affected by the magnetic field from the superconducting coil as the object to be cooled 1.

[0049] [E] Fifth embodiment (Figures 7 and 8) Figure 7 is a piping diagram showing the configuration of the cryogenic cooling device according to the fifth embodiment. In this fifth embodiment, parts that are the same as in the first embodiment are denoted by the same reference numerals as in the first to fourth embodiments, and their explanation is simplified or omitted.

[0050] The difference between the cryogenic cooling device 50 of this fifth embodiment and the first to fourth embodiments is that the vacuum insulated container has a first vacuum insulated container 51X (Figure 7) that houses the heat exchanger 14, the cooling stage 15A of the refrigerator 15 and the ejector 16, or a first vacuum insulated container 51Y (Figure 8) that houses the low-temperature fan 31, the cooling stage 15A of the refrigerator 15 and the ejector 16, and a plurality of second vacuum insulated containers 51-1, 52-2 that house the object to be cooled 1, respectively.

[0051] In this cryogenic cooling device 50, the other branch gas pipe 12B in the first vacuum insulated container 51X or 51Y is further branched at the outlet (downstream side) of the cooling stage 15A of the refrigerator 15 to correspond to multiple objects to be cooled 1, for example, becoming refrigerator-side branch gas pipes 12B-1 and 12B-2 as cooling source-side branch gas pipes. The refrigerator-side branch gas pipe 12B-1 is routed to the objects to be cooled 1 in the second vacuum insulated container 52-1 via the inlet-side insulated gas pipe 53. The refrigerator-side branch gas pipe 12B-2 is routed to the objects to be cooled 1 in the second vacuum insulated container 52-2 via the inlet-side insulated gas pipe 53. These chiller-side branch gas pipes 12B-1 and 12B-2 merge upstream of the suction port 21 of the ejector 16 in the first vacuum-insulated container 51X or 51Y via the outlet-side insulated gas pipe 54 on the downstream side of the object to be cooled 1, and are connected to the other branch gas pipe 12B, which in turn is connected to the suction port 21 of the ejector 16.

[0052] Here, the inlet-side insulated gas piping 53 and the outlet-side insulated gas piping 54 are provided between the first vacuum insulated container 51X or 51Y and the plurality of second vacuum insulated containers 52-1, 52-2. The inlet-side insulated gas piping 53 and the outlet-side insulated gas piping 54 connect the chiller-side branch gas piping 12B-1 in the first vacuum insulated container 51X or 51Y to the chiller-side branch gas piping 12B-1 in the second vacuum insulated container 52-1, and further connect the chiller-side branch gas piping 12B-2 in the first vacuum insulated container 51X or 51Y to the chiller-side branch gas piping 12B-2 in the second vacuum insulated container 52-2. In this fifth embodiment as well, the compressor 13 is located in the room temperature region N outside the first vacuum insulated container 51X. The cooling source is not limited to the chiller 15, but may be the liquid refrigerant tank 27 of the second embodiment.

[0053] In the cryogenic cooling device 50 described above, the cooling gas X discharged from the outlet 23 of the ejector 16, which has a pump function, and diverted to the other branch gas pipe 12B, is cooled by the cooling stage 15A of the refrigerator 15, then cools the object to be cooled 1 in the second vacuum insulated container 52-1 via the refrigerator-side branch gas pipe 12B-1, and cools the object to be cooled 1 in the second vacuum insulated container 52-2 via the refrigerator-side branch gas pipe 12B-2, before merging and being drawn into the suction port 21 of the ejector 16 and circulating within the second circulation loop 18.

[0054] As configured as described above, this fifth embodiment also provides the same effects as the first to fourth embodiments (1) to (6), as well as the following effect (7).

[0055] (7) Multiple objects to be cooled 1 are cooled simultaneously using one compressor 13, heat exchanger 14, refrigerator 15 and ejector 16 for each, or using one low-temperature fan 31, refrigerator 15 and ejector 16 for each. Therefore, compared to the case where multiple objects to be cooled 1 are cooled individually using one compressor 13, heat exchanger 14, refrigerator 15 and ejector 16 for each, or using one low-temperature fan 31, refrigerator 15 and ejector 16 for each, firstly, the number of compressors 13, heat exchangers 14, refrigerators 15, ejectors 16 and low-temperature fans 31 can be reduced. Secondly, the overall amount of cooling gas X flowing in from the room temperature region N is reduced, which reduces the heat load on the cooling source including the refrigerator 15 associated with the inflow of this cooling gas X, and allows for efficient cooling of the objects to be cooled 1 by this cooling source. Thirdly, since the need for multiple low-temperature fans 31 can be avoided, the amount of heat entering the low-temperature fan 31 from the mechanical connection part in the room temperature region N can be reduced overall, and by reducing the heat load of the cooling source including the refrigerator 15, the object to be cooled 1 can be cooled efficiently.

[0056] [F] Sixth embodiment (Figures 9 and 10) Figure 9 is a piping diagram showing the configuration of the cryogenic cooling device according to the sixth embodiment. In this sixth embodiment, parts that are the same as those in the first to third embodiments are denoted by the same reference numerals as in the first to third embodiments, thereby simplifying or omitting their explanation.

[0057] The difference between the cryogenic cooling device 60 of this sixth embodiment and the first to third embodiments is that it includes a valve 61 installed in one of the branch gas pipes 12A in the gas pipe 12 connected to the discharge port 23 of the ejector 16, a sensor 62 that measures the state of the object to be cooled 1 or the state of the cooling gas X inside the object to be cooled 1 (for example, both are temperature), and a monitoring device 63 that adjusts the opening degree of the valve 61 based on the measurement value from the sensor 62.

[0058] If the heat load on the object being cooled 1 unexpectedly becomes excessive from a steady state, the density of the cooling gas X flowing through the gas piping 12 in the low-temperature region M decreases, increasing the pressure loss, and the gas flow rate of the cooling gas X flowing into the object being cooled 1 decreases, the temperature of the object being cooled 1 or the temperature of the cooling gas X inside the object being cooled 1 will rise. The monitoring device 63 adjusts the opening of the valve 61 to a smaller value when the measurement value from the sensor 62 exceeds the threshold, and the cooling stage of the refrigerator 15 15A The flow rate of the cooling gas X that reaches the object to be cooled 1 is increased, thereby controlling the flow rate to suppress the temperature rise of the object to be cooled 1. Note that the cooling source is not limited to the refrigerator 15, but may also be the liquid refrigerant tank 27 in the second embodiment.

[0059] As configured as described above, this sixth embodiment also provides the same effects as the first to third embodiments (1) to (5), as well as the following effect (8).

[0060] (8) A valve 61 is provided in one of the branch gas pipes 12A downstream of the discharge port 23 of the ejector 16. Based on measurements from a sensor 62 that measures the state of the object to be cooled 1 or the state of the cooling gas X inside the object to be cooled 1 (for example, both are temperature), the monitoring device 63 adjusts the opening of the valve 61 to suppress the temperature rise of the object to be cooled 1. As a result, even if the heat load on the object to be cooled 1 becomes unexpectedly excessive, the temperature rise of the object to be cooled 1 is suppressed, thereby ensuring the integrity of the object to be cooled 1.

[0061] [G] Seventh embodiment (Figures 11 and 12) Figure 11 is a piping diagram showing the configuration of the cryogenic cooling device according to the seventh embodiment. In this seventh embodiment, parts that are the same as those in the first to sixth embodiments are denoted by the same reference numerals as in the first to sixth embodiments, and the explanation is simplified or omitted.

[0062] The difference between the cryogenic cooling device 70 of this seventh embodiment and the first to fifth embodiments (particularly the fifth embodiment) is that multiple valves 72-1 and 72-2 are provided upstream of the confluence point 71 in the first vacuum insulated container 51X or 51Y in multiple chiller-side branch gas pipes 12B-1 and 12B-2, each containing one object to be cooled 1 in multiple second vacuum insulated containers 52-1 and 52-2. Furthermore, this cryogenic cooling device 70 is provided with multiple sensors 73-1 and 73-2 that measure the state of multiple objects to be cooled 1 or the state of the cooling gas X within the objects to be cooled 1 (for example, temperature in both cases), and a monitoring device 74 is provided that adjusts the opening degree of valves 72-1 and 72-2 based on the measurements of these multiple sensors 73-1 and 73-2.

[0063] When the heat load on a specific object 1 among several objects 1 increases, and the temperature of this object 1 or the temperature of the cooling gas X inside this object 1 exceeds a threshold, sensors 73-1 and 73-2 measure the temperature rise. For example, when the measurement value of sensor 73-1 exceeds the threshold, the monitoring device 74 increases the opening of the valve 72-1 corresponding to the object 1 equipped with sensor 73-1, thereby increasing the gas flow rate of the cooling gas X flowing to the object 1 equipped with sensor 73-1, and controlling it to suppress the temperature difference between the multiple objects 1. Note that the cooling source is not limited to the refrigerator 15, but may also be the liquid refrigerant tank 27 in the second embodiment.

[0064] As configured as described above, this seventh embodiment also provides the same effects as those of the first to fifth embodiments (1) to (7), as well as the following effect (9).

[0065] (9) Valves 72-1 and 72-2 are provided upstream of the confluence point 71 in the multiple chiller-side branch gas pipes 12B-1 and 12B-2, each of which has a single object to be cooled 1. Based on the measurements of sensors 73-1 and 73-2 that measure the state (e.g., temperature) of each of the multiple objects to be cooled 1 or the cooling gas X within the objects to be cooled 1, the monitoring device 74 increases the opening of the valves 72-1 and 72-2 corresponding to the object to be cooled 1 whose temperature has risen above a threshold. This prevents the temperature of a particular object to be cooled 1 from rising, thereby ensuring the integrity of all of the multiple objects to be cooled 1.

[0066] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be carried out in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention, and such substitutions, modifications, and combinations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0067] 1... Object to be cooled, 10... Cryogenic cooling device, 11... Vacuum insulated container (insulated container), 12... Gas piping, 12A... One branch gas piping, 12B... The other branch gas piping, 12B-1, 12B-2... Refrigerator side branch gas piping (cooling source side branch gas piping), 13... Compressor, 14... Heat exchanger, 15... Refrigerator (cooling source), 19... Drive port, 21... Inlet, 23... Outlet, 25... Cryogenic cooling device, 26... Liquid refrigerant, 27... Liquid refrigerant tank (cooling source), 30... Cryogenic cooling device, 31... Low temperature fan, 40... Cryogenic cooling device, 41X 41Y…First vacuum insulated container, 42…Second vacuum insulated container, 43…Insulated gas piping, 50…Cryogenic cooling device, 51X, 51Y…First vacuum insulated container, 52-1, 52-2…Second vacuum insulated container, 53…Inlet side insulated gas piping, 54…Outlet side insulated gas piping, 60…Cryogenic cooling device, 61…Valve, 62…Sensor, 63…Monitoring device, 70…Cryogenic cooling device, 71…Confluence point, 72-1, 72-2…Valve, 73-1, 73-2…Sensor, 74…Monitoring device, M…Low temperature region, N…Room temperature region, X…Cooling gas

Claims

1. A gas piping system is provided that spans both a room temperature region and a low temperature region, separated by an insulated container, and the object to be cooled is placed in the low temperature region. A compressor is installed in the gas piping within the aforementioned room temperature range and circulates the cooling gas within the gas piping. A heat exchanger is installed in the gas piping within the low-temperature region and cools the high-pressure cooling gas from the compressor by exchanging heat with the low-pressure cooling gas returning to the compressor, A cooling source is provided in the gas piping within the low-temperature region, located upstream of the object to be cooled, to cool the cooling gas and to cool the object to be cooled with this cooling gas. The gas piping within the low-temperature region is disposed between the heat exchanger and the cooling source and includes an ejector that performs a pumping function for the cooling gas, The ejector is configured such that its drive port is connected to the high-pressure side outlet of the heat exchanger via the gas piping, the gas piping connected to the discharge port is branched, one branch gas piping is connected to the low-pressure side inlet of the heat exchanger, and the other branch gas piping is connected to the suction port of the ejector after the cooling source and the object to be cooled are sequentially arranged. Furthermore, a valve is provided in the one branch gas pipe in the gas piping connected to the discharge port of the ejector, A sensor for measuring the state of the object to be cooled or the state of the cooling gas within the object to be cooled, A cryogenic cooling device characterized by comprising a monitoring device that adjusts the opening degree of the valve based on measurements from the sensor and controls it to suppress the temperature rise of the object to be cooled.

2. A gas pipe is installed in a low-temperature region surrounded by an insulated container, and the object to be cooled is placed inside. A low-temperature fan is installed in the gas piping to circulate the cooling gas within the gas piping, A cooling source is provided in the gas piping upstream of the object to be cooled to cool the cooling gas, and to cool the object to be cooled by this cooling gas, The gas piping includes an ejector disposed between the low-temperature fan and the cooling source, which performs a pumping function for the cooling gas, The ejector is configured such that its drive port is connected to the high-pressure side outlet of the low-temperature fan via the gas piping, the gas piping connected to the discharge port is branched, one branch gas piping is connected to the low-pressure side inlet of the low-temperature fan, and the other branch gas piping is connected to the suction port of the ejector after the cooling source and the object to be cooled are sequentially arranged. Furthermore, a valve is provided in the one branch gas pipe in the gas piping connected to the discharge port of the ejector, A sensor for measuring the state of the object to be cooled or the state of the cooling gas within the object to be cooled, A cryogenic cooling device characterized by comprising a monitoring device that adjusts the opening degree of the valve based on measurements from the sensor and controls it to suppress the temperature rise of the object to be cooled.

3. The cryogenic cooling apparatus according to claim 1 or 2, characterized in that the insulated container comprises a first insulated container for housing a cooling source and an ejector, and a second insulated container for housing an object to be cooled, and the gas piping within both of these insulated containers is connected by insulated gas piping.

4. The aforementioned insulated container comprises a first insulated container for housing a cooling source and an ejector, and a second insulated container for housing the object to be cooled. The second insulated container is provided in multiple locations, each containing the object to be cooled. The cryogenic cooling apparatus according to claim 1 or 2, characterized in that the other branch gas piping in the first insulated container is further branched at the outlet of the cooling source, and these cooling source-side branch gas pipings, after arranging the objects to be cooled in the plurality of second insulated containers via the inlet-side insulated gas piping, merge upstream of the suction port of the ejector in the first insulated container via the outlet-side insulated gas piping and connect to the suction port.

5. Multiple valves are located upstream of the confluence point in multiple cooling source-side branch gas pipes, each containing a cooling object within a multiple second insulated container, Multiple sensors for measuring the state of multiple objects to be cooled or the state of cooling gas within multiple objects to be cooled, The cryogenic cooling apparatus according to claim 4, characterized in that it is configured to include a monitoring device that adjusts the opening degree of a plurality of valves based on measurements from a plurality of sensors and controls them to suppress temperature differences between a plurality of objects to be cooled.

6. The cryogenic cooling apparatus according to claim 1 or 2, characterized in that the pressure of the cooling gas drawn into the inlet of the ejector is set to be equal to or greater than the critical pressure of the cooling gas.

7. A superconducting device characterized by having a cryogenic cooling device according to claim 1 or 2, wherein the object to be cooled is a superconducting coil.

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