Superconducting motor system

Abstract

This superconducting motor system comprises: a shaft; a box body that is disposed around the shaft and forms a refrigerant space in which a refrigerant can be accommodated; a rotor provided to the shaft; a superconducting stator coil accommodated in the refrigerant space and disposed around the rotor; and a superconducting magnetic bearing accommodated in the refrigerant space and having a superconducting coil that supports the shaft.

Description

Superconducting motor system

[0001] This disclosure relates to a superconducting motor system.

[0002] In the field of electric motors, high rotational efficiency is required. For this reason, for example, as described in Patent Document 1, there is a device using a superconducting motor in order to reduce losses due to electric resistance. Such a superconducting motor needs to cool the conductive part. Patent Document 1 describes using liquid hydrogen for a fuel cell as a refrigerant for the superconducting motor.

[0003] Japanese Patent Application Laid-Open No. 2005-86914

[0004] As described above, in order to obtain higher rotational efficiency, there is a device using a superconducting motor as an electric motor. However, even when using a superconducting motor, a configuration that can obtain even higher rotational efficiency is required.

[0005] Therefore, this disclosure will describe a superconducting motor system capable of obtaining higher rotational efficiency.

[0006] The superconducting motor system according to one aspect of this disclosure includes a shaft, a box body disposed around the shaft, forming a refrigerant space capable of accommodating a refrigerant inside, and having a magnetically permeable portion facing the shaft, a rotor provided on the shaft, a superconducting stator coil accommodated in the refrigerant space and disposed around the rotor, and a superconducting magnetic bearing having a superconducting coil that accommodates the shaft and supports the shaft.

[0007] According to one aspect of this disclosure, higher rotational efficiency can be obtained.

[0008] Figure 1 is a block diagram showing the schematic configuration of a propulsion unit to which the superconducting motor system according to the first embodiment is applied. Figure 2(a) is a cross-sectional view of the second piping section in Figure 1. Figure 2(b) is a cross-sectional view along the line IIb-IIb in Figure 2(a). Figure 2(c) is a cross-sectional view showing an enlarged view of the power transmission cable in Figure 2(b). Figure 3 is a cross-sectional view showing the schematic configuration of the superconducting motor system in Figure 1. Figure 4 is a cross-sectional view showing the schematic configuration of a superconducting motor system according to a first modification of the first embodiment. Figure 5(a) is a side view of the thrust disk in Figure 4. Figure 5(b) is a front view of the thrust disk in Figure 4. Figure 6 is a cross-sectional view showing the schematic configuration of a superconducting motor system according to a second modification of the first embodiment. Figure 7 is a cross-sectional view showing the schematic configuration of a further modification of the superconducting motor system according to the second modification of the first embodiment. Figure 8 is a cross-sectional view showing the schematic configuration of a superconducting motor system according to the second embodiment. Figure 9 is a cross-sectional view showing the schematic configuration of a superconducting motor system according to the third embodiment. Figure 10 is a cross-sectional view showing the schematic configuration of a superconducting motor system according to a modification of the third embodiment. Figure 11(a) is a cross-sectional view showing a schematic configuration of a superconducting motor system according to a modified example of the fourth embodiment. Figure 11(b) is a cross-sectional view along the line XIb-XIb in Figure 11(a).

[0009] A superconducting motor system according to one aspect of the present disclosure comprises a shaft, a box body disposed around the shaft and having a refrigerant space inside which a refrigerant can be contained, and in which the portion facing the shaft is magnetically permeable, a rotor provided on the shaft, a superconducting stator coil housed in the refrigerant space and disposed around the rotor, and a superconducting magnetic bearing housed in the refrigerant space and having a superconducting coil that supports the shaft.

[0010] In this superconducting motor system, the superconducting stator coil and superconducting magnetic bearing are housed within a coolant space formed inside a casing. This allows the superconducting motor system to cool the superconducting stator coil, which rotates the shaft, and the superconducting magnetic bearing that supports the shaft, using the coolant contained within the coolant space. As a result, the superconducting motor system can efficiently rotate the shaft through the interaction of magnetic fields between the superconducting stator coil and the rotor. Furthermore, the superconducting motor system can support the shaft non-contact with the superconducting magnetic bearing. This allows the superconducting motor system to support the shaft in a state of high rotational efficiency. Thus, the superconducting motor system can achieve higher rotational efficiency.

[0011] In the superconducting motor system described above, the housing comprises a first housing that houses a first portion of the shaft and is permeable to magnetism, and a second housing that houses the first housing and forms a coolant space between itself and the first housing, and the rotor may be provided on the first portion of the shaft. In this superconducting motor system, a coolant space is formed between the first housing that houses the shaft and the second housing that houses the first housing. As a result, the superconducting motor system can cool the superconducting stator coil for rotating the shaft and the superconducting magnetic bearing that supports the shaft with the coolant contained in this coolant space.

[0012] The superconducting motor system described above may include a pressure reduction mechanism for reducing the pressure inside the first housing. Here, the first housing contains a first portion of the shaft and a rotor attached to the first portion of the shaft. In other words, in the superconducting motor system, the rotating parts (the rotating rotor and the first portion of the shaft) are housed inside the first housing. As a result, the superconducting motor system can reduce windage losses caused by friction between the gas and the rotating parts by reducing the pressure inside the first housing containing the rotating parts using the pressure reduction mechanism. In this way, the superconducting motor system can obtain even higher rotational efficiency by reducing the pressure inside the first housing.

[0013] In the superconducting motor system described above, the depressurization mechanism may have a depressurization blade attached to a first portion of the shaft, and the gas inside the first housing may be discharged to the outside of the first housing by the rotation of the depressurization blade. Because the depressurization blade is attached to the first portion of the shaft, it rotates together with the shaft which is rotated by the superconducting stator coil and rotor. In this case, the superconducting motor system can reduce the pressure inside the first housing by the rotation of the depressurization blade which rotates together with the shaft.

[0014] In the superconducting motor system described above, a main blade is attached to the second portion of the shaft that extends outside the first housing, and a depressurizing blade may be mounted in a direction such that the direction of the thrust force applied to the shaft by the rotation of the depressurizing blade and the direction of the thrust force applied to the shaft by the rotation of the main blade are opposite to each other. In this case, the superconducting motor system can cancel out or reduce the thrust force applied to the shaft by the rotation of the main blade by the thrust force generated on the shaft by the rotation of the depressurizing blade. This makes it easier for the superconducting motor system to support the shaft in the thrust direction.

[0015] In the superconducting motor system described above, the superconducting magnetic bearing may include at least one of a superconducting thrust bearing that supports the shaft in the axial direction and a superconducting radial bearing that supports the shaft in the radial direction. In this case, the superconducting motor system can efficiently support the shaft using these superconducting magnetic bearings.

[0016] In the superconducting motor system described above, the magnets provided on the rotor may be of the magnetic flux-concentrating type. In this case, the superconducting motor system can achieve higher rotational efficiency by using a rotor in which the magnets are of the magnetic flux-concentrating type.

[0017] In the superconducting motor system described above, the refrigerant is liquid hydrogen, and the second housing may consist of a reserve tank located in the middle of the liquid hydrogen supply path from the main tank that stores liquid hydrogen to the receiving device. For example, if an imbalance occurs in the liquid hydrogen within the main tank, it is conceivable that liquid hydrogen may not be properly supplied from the main tank to the receiving device (e.g., the supply may be interrupted). Therefore, in the superconducting motor system, the second housing, which forms a refrigerant space for cooling the superconducting stator coils, etc., functions as a reserve tank, thereby enabling a more appropriate supply of liquid hydrogen to the receiving device.

[0018] In the superconducting motor system described above, the receiving device is a fuel cell, and a superconducting power transmission cable for transmitting power generated by the fuel cell is arranged in the supply piping that forms the supply path of liquid hydrogen from the second housing to the fuel cell, and at least one of the superconducting stator coil and the superconducting coil may be supplied with power from the fuel cell via the superconducting power transmission cable. In this case, the superconducting cable can be cooled by the liquid hydrogen supplied from the second housing to the fuel cell. This makes it possible to improve the power transmission efficiency in the superconducting power transmission cable.

[0019] Embodiments of this disclosure will be described below with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant explanations are omitted.

[0020] (First Embodiment) A first embodiment of the superconducting motor system will be described. As shown in Figure 1, the superconducting motor system 1 in this embodiment is applied, as an example, to a propulsion unit 100 that serves as a power source for an airplane. The propulsion unit 100 is mounted on the airplane. The superconducting motor system 1 rotates the main blade M, and the aircraft flies using the thrust force generated by the rotation of the main blade M. The airplane may fly using only the power of the propulsion unit 100 equipped with the superconducting motor system 1. Alternatively, the airplane may be equipped with a main propulsion unit such as a jet engine in addition to the propulsion unit 100, and the propulsion unit 100 may be used as an auxiliary power source for the main propulsion unit to fly.

[0021] The propulsion unit 100 comprises a superconducting motor system 1, a main tank 2, and a fuel cell (supply destination device) 3. The fuel cell 3 is a device that generates electricity by chemically reacting hydrogen and oxygen. The electricity generated by the fuel cell 3 is used to power the superconducting motor system 1, etc. The main tank 2 and the fuel cell 3 are connected to each other by a pipe L. Liquid hydrogen is stored in the main tank 2. The pipe L serves as a supply route for supplying liquid hydrogen from the main tank 2 to the fuel cell 3. The fuel cell 3 uses the liquid hydrogen supplied from the main tank 2 via the pipe L as the hydrogen used for generating electricity. In addition, if the aircraft is equipped with a hydrogen combustion jet engine as the main propulsion unit's jet engine, the liquid hydrogen in the main tank 2 may be supplied to the hydrogen combustion jet engine (supply destination device).

[0022] The superconducting motor system 1 is installed in the middle of the piping L. The superconducting motor system 1 drives the main blade M with electricity generated by the fuel cell 3. Liquid hydrogen is supplied to the superconducting motor system 1 from the main tank 2 via the first piping section L1 of the piping L. Liquid hydrogen is also supplied to the fuel cell 3 from the superconducting motor system 1 via the second piping section L2 of the piping L. The superconducting motor system 1 has a refrigerant space R2 (see Figure 3) capable of holding a predetermined amount of liquid hydrogen. The liquid hydrogen supplied from the main tank 2 to the fuel cell 3 via the piping L is supplied to the fuel cell 3 via the refrigerant space R2 in the superconducting motor system 1. In other words, the superconducting motor system 1 functions as a reserve tank for the liquid hydrogen supplied from the main tank 2 to the fuel cell 3.

[0023] When the superconducting motor system 1 functions as a reserve tank, liquid hydrogen can be pumped to the fuel cell 3 by pressurizing the main tank 2 and using the siphon principle. In this case, for example, the pressure in the gas phase inside the main tank 2 may be increased by raising the temperature of the main tank 2. This eliminates the need for a pump to pump the liquid hydrogen, and allows for efficient pumping of liquid hydrogen. It should be noted that the method is not limited to raising the temperature of the main tank 2, but the main tank 2 may also be pressurized by known pressurization methods.

[0024] In this embodiment, the power transmission cable (superconducting power transmission cable) C (see Figure 2(a)) that transmits the power generated by the fuel cell 3 to the superconducting motor system 1 is located within the second piping section (supply piping) L2, which forms the supply path for liquid hydrogen from the outer housing 40 to the fuel cell 3. The power transmission cable C in this embodiment is made of a superconducting material (superconducting wire). This power transmission cable C is cooled by being immersed in liquid hydrogen within the second piping section L2. This improves the power transmission efficiency of the power transmission cable C.

[0025] As an example, the second piping section L2 in this embodiment is configured to include an inner pipe L21 and an outer pipe L22, as shown in Figures 2(a) and 2(b). The inner pipe L21 is passed inside the outer pipe L22. The outer surface of the outer pipe L22 is covered by a sheath L23, for example. Corrugated pipes may be used as the inner pipe L21 and the outer pipe L22, for example. However, the inner pipe L21 and the outer pipe L22 may be composed of pipes other than corrugated pipes. Liquid hydrogen LH2 supplied from the superconducting motor system 1 to the fuel cell 3 flows through the inner pipe L21. Liquid hydrogen LH2 supplied from the superconducting motor system 1 to the fuel cell 3 also flows between the inner pipe L21 and the outer pipe L22.

[0026] In this embodiment, the power transmission cable C, which transmits the electricity generated by the fuel cell 3 to the superconducting motor system 1, is, for example, located inside the inner piping L21. That is, the power transmission cable C is immersed in the liquid hydrogen LH2 flowing inside the inner piping L21. As an example, the power transmission cable C in this embodiment is a two-pole single-core coaxial cable, as shown in Figure 2(c). Specifically, the power transmission cable C is composed of a cylindrical positive electrode C1 and a cylindrical negative electrode C2. The positive electrode C1 is passed inside the cylindrical negative electrode C2. The positive electrode C1 and the negative electrode C2 are each made of a superconducting material (superconducting wire).

[0027] In this embodiment, the power transmission cable C is composed of, for example, a former C11, an insulating layer C12, an insulating layer C13, and a protective layer C14. The former C11, insulating layer C12, insulating layer C13, and protective layer C14 are each cylindrical in shape. The positive electrode C1 is provided on the outside of the former C11. The insulating layer C12 is provided between the positive electrode C1 and the negative electrode C2. The insulating layer C13 is provided so as to cover the outer circumferential surface of the insulating layer C12. The protective layer C14 is provided so as to cover the outer circumferential surface of the insulating layer C13. Thus, the power transmission cable C has a cylindrical shape with a space inside the former C11. In the power transmission cable C, liquid hydrogen LH2 supplied from the superconducting motor system 1 to the fuel cell 3 flows through the space inside the former C11. In other words, in the power transmission cable C, liquid hydrogen LH2 flows both in the center and on the outer side of the power transmission cable C. As a result, the positive electrode C1 and negative electrode C2, which are made of superconducting material, can be efficiently cooled by the liquid hydrogen LH2 from both the central side and the outer surface side of the power transmission cable C.

[0028] Here, for example, when an aircraft equipped with the propulsion unit 100 is performing various inspections on the ground, it may be necessary to ensure the power distribution function via the power transmission cable C when liquid hydrogen is not supplied to the fuel cell 3. When liquid hydrogen is not supplied to the fuel cell 3, liquid hydrogen does not flow inside the inner piping L21 of the second piping section L2 and inside the power transmission cable C. In such cases, for example, liquid nitrogen may be supplied inside the inner piping L21 of the second piping section L2 and inside the power transmission cable C, and the power distribution function via the power transmission cable C may be ensured by using liquid nitrogen as a refrigerant. In addition, in this case, the inner piping L21 may be insulated by creating a reduced pressure (vacuum) in the space between the inner piping L21 and the outer piping L22 of the second piping section L2.

[0029] The number of superconducting motor systems 1, main tanks 2, and fuel cells 3 in the propulsion unit 100 described using Figure 1 may be one or multiple. The number of superconducting motor systems 1, main tanks 2, and fuel cells 3 may be appropriate depending on the size, type, and performance of the aircraft to which the propulsion unit 100 is applied. For example, the relatively heavy fuel cells 3 may be mounted so as to be suspended from the left and right main wings of the aircraft. For example, the main tanks 2 may be located in the fuselage of the aircraft (for example, in the part near the rear of the fuselage). For example, the superconducting motor system 1 with main blades M may be mounted in the rear part of the fuselage of the aircraft or suspended from the main wings of the aircraft.

[0030] Next, the details of the superconducting motor system 1 will be described. The superconducting motor system 1 in this embodiment is configured using an inner rotor radial gap type motor. More specifically, as shown in Figure 3, the superconducting motor system 1 is configured to include a shaft 10, a rotor 20, an inner housing (first housing) 30, an outer housing (second housing) 40, and a superconducting stator coil 50. In the description of the superconducting motor system 1, the axial direction is the direction along the extending direction of the shaft 10. The radial direction is the direction along the radial direction of the shaft 10. The circumferential direction is the direction around the outer circumferential surface of the shaft 10.

[0031] The inner housing 30 forms a rotating body chamber R1 on its interior that houses a part of the shaft 10 and a rotating body such as the rotor 20. In this embodiment, the inner housing 30 is made of a magnetically permeable material. The shaft 10 has a first portion 10a that is housed inside the inner housing 30 and a second portion 10b that extends outside the inner housing 30. The second portion 10b also protrudes (extends) outside the outer housing 40. The main blade M is attached to the second portion 10b.

[0032] The rotor 20 is attached to the first portion 10a of the shaft 10. The rotor 20 functions as the rotor of an electric motor. The rotor 20 is equipped with magnets (permanent magnets). In this embodiment, the magnets provided on the rotor 20 are of the magnetic flux condensing type. A magnetic flux condensing type is a magnet constructed by a field method that concentrates magnetic flux in a predetermined direction. A magnetic flux condensing type is a magnet composed of multiple magnet bodies, in which the magnetic field is concentrated on one side of the magnets. As an example, the magnets of the rotor 20, which is a magnetic flux condensing type, are arranged in a Halbach array. In other words, the rotor 20 in this case is a Halbach array rotor. This rotor 20 may be, for example, a Halbach hollow permanent magnet rotor. However, the magnets provided on the rotor 20 are not limited to being in a Halbach array. The magnets of the rotor 20 may have a magnetic flux condensing magnetic field by a structure other than a Halbach array. Note that the configuration of the rotor 20 is not limited to one using magnets. For example, the rotor 20 may be configured to include windings (coils) that generate a magnetic field.

[0033] The outer housing 40 houses the inner housing 30. The outer housing 40 covers the outer surface of the inner housing 30. The outer housing 40 forms part of the rotating body chamber R1 that houses a rotating body such as a rotor 20. Specifically, in the rotating body chamber R1, the axial central portion is formed by the inner housing 30. In the rotating body chamber R1, both axial ends are formed by the outer housing 40. Thus, in this embodiment, the rotating body chamber R1 is formed, for example, by the inner housing 30 and the outer housing 40. In the rotating body chamber R1, the end on the side where the main blade M is provided in the axial direction is closed by a seal S installed between the outer housing 40 and the shaft 10. The seal S may, for example, be a labyrinth seal. However, the configuration of the seal S is not particularly limited as long as it can seal the space between the outer housing 40 and the shaft 10 airtightly (generally airtightly). In the rotating body chamber R1, the end opposite to the side where the main blade M is provided in the axial direction is closed by the outer housing 40. Thus, the rotating chamber R1, which houses the first portion 10a of the shaft 10 and the rotor 20, is a closed space enclosed by the inner housing 30 and the outer housing 40.

[0034] Furthermore, the outer casing 40 forms a refrigerant space R2 between itself and the inner casing 30, which is capable of accommodating refrigerant. The refrigerant space R2 is surrounded by surfaces including the inner surface of the outer casing 40 and the outer surface of the inner casing 30. In this embodiment, the refrigerant accommodating in the refrigerant space R2 is liquid hydrogen LH2 supplied from the main tank 2 to the fuel cell 3 via piping L. The outer casing 40 is connected to a first piping section L1 and a second piping section L2, respectively. The liquid hydrogen LH2 supplied from the main tank 2 to the fuel cell 3 is supplied into the refrigerant space R2 from the first piping section L1, and then supplied from the refrigerant space R2 to the fuel cell 3 via the second piping section L2. In other words, the liquid hydrogen LH2 supplied from the main tank 2 to the fuel cell 3 passes through the refrigerant space R2 of the superconducting motor system 1 before being supplied to the fuel cell 3. Thus, the outer casing 40 of the superconducting motor system 1 constitutes a reserve tank provided in the middle of the piping L for liquid hydrogen LH2 from the main tank 2 to the fuel cell 3.

[0035] Thus, the inner housing 30 and the outer housing 40 constitute a box body 70 that forms a refrigerant space R2 capable of containing a refrigerant (liquid hydrogen LH2) inside. The box body 70 is arranged around the shaft 10. Furthermore, the inner housing 30 of the box body 70 is permeable to magnetism. In other words, at least the portion of the box body 70 facing the shaft 10 (the portion facing the outer circumferential surface of the shaft 10) is permeable to magnetism. In this embodiment, the box body 70 forms a substantially cylindrical refrigerant space R2 that surrounds the shaft 10 over its entire circumference.

[0036] The superconducting stator coil 50 is housed in the coolant space R2. The superconducting stator coil 50 is positioned to surround the rotor 20, sandwiching the inner housing 30. The superconducting stator coil 50 is equipped with a superconducting coil made of superconducting material. The superconducting stator coil 50 faces the rotor 20 in the radial direction.

[0037] Furthermore, the superconducting motor system 1 is equipped with a superconducting magnetic bearing B that rotatably supports the shaft 10. In this embodiment, the superconducting magnetic bearing B includes a superconducting thrust bearing B1 and a superconducting radial bearing B2. The superconducting thrust bearing B1, which is a type of superconducting magnetic bearing, supports the shaft 10 in the axial direction. In other words, the superconducting thrust bearing B1 defines the axial position of the shaft 10. The superconducting radial bearing B2, which is a type of superconducting magnetic bearing, supports the shaft 10 in the radial direction. In other words, the superconducting radial bearing B2 defines the radial position of the shaft 10. The superconducting thrust bearing B1 and the superconducting radial bearing B2 each have a superconducting coil made of a superconducting material. The superconducting thrust bearing B1 and the superconducting radial bearing B2 are each housed in a coolant space R2.

[0038] The superconducting radial bearing B2 faces the outer circumferential surface of the first portion 10a of the shaft 10 in the radial direction, with the inner housing 30 in between. The superconducting radial bearing B2 supports the shaft 10 itself in the radial direction. The superconducting radial bearing B2 supports the shaft 10 in the radial direction by attracting the shaft 10 with magnetic force. In this embodiment, as an example, the superconducting radial bearing B2 is provided at two locations in the extending direction of the shaft 10, sandwiching the rotor 20.

[0039] A thrust disk 11 is attached to the shaft 10. The thrust disk 11 is housed in a rotating chamber R1. The superconducting thrust bearing B1 faces the thrust disk 11 in the axial direction, with the inner housing 30 in between. The superconducting thrust bearing B1 is provided in two locations in the axial direction, sandwiching the thrust disk 11. The superconducting thrust bearing B1 supports the shaft 10 in the axial direction by attracting the thrust disk 11 to one and the other side in the axial direction by magnetic force.

[0040] The number and positions of the superconducting thrust bearings B1 and superconducting radial bearings B2 are not limited to the configuration shown in Figure 3. The superconducting thrust bearings B1 and superconducting radial bearings B2 can be provided in an appropriate number and at appropriate positions so as to be able to support the shaft 10 in the axial and radial directions, respectively.

[0041] The superconducting motor system 1 further includes a vacuum pump 60. Here, the rotating chamber R1 is provided with an outlet R1a. When the vacuum pump 60 is not installed, the rotating chamber R1 communicates with the outside space via the outlet R1a. In this embodiment, the outlet R1a is, for example, formed by an opening provided in the outer housing 40. The portion of the outer housing 40 where the outlet R1a is provided is the portion of the outer housing 40 that forms the rotating chamber R1. The vacuum pump 60 is attached to the outlet R1a provided in the outer housing 40. The vacuum pump 60 discharges the air (gas) inside the rotating chamber R1 to the outside via the outlet R1a, creating a reduced pressure state (near-vacuum state) inside the rotating chamber R1. In this way, the vacuum pump 60 functions as a pressure reducing mechanism that reduces the pressure inside the inner housing 30.

[0042] Furthermore, the superconducting motor system 1 may further include touchdown bearings G. In this embodiment, the touchdown bearings G are provided at two locations in the extending direction of the shaft 10, sandwiching the rotor 20 and the thrust disk 11. In this embodiment, as an example, the outer ring of the touchdown bearings G is attached to the outer housing 40. The inner ring of the touchdown bearings G surrounds the outer circumferential surface of the shaft 10. The touchdown bearings G support the shaft 10 when the shaft 10 is not supported by the superconducting radial bearings B2. Note that the number and location of the touchdown bearings G are not limited to the configuration shown in Figure 3. The touchdown bearings G may, for example, be provided outside the outer housing 40. The touchdown bearings G should be provided in an appropriate number and at appropriate locations so as to be able to support the shaft 10 in the radial direction.

[0043] In this superconducting motor system 1, a magnetic field is formed by supplying current to the superconducting stator coil 50. When the magnetic field generated by the superconducting stator coil 50 interacts with the magnetic field of the rotor 20, a rotational force is generated in the rotor 20, causing the shaft 10 to which the rotor 20 is attached to rotate. The power supplied to this superconducting stator coil 50 is the power generated by the fuel cell 3 and used is the power supplied to the superconducting motor system 1 via the power transmission cable C. Also, the power supplied to the superconducting coil of the superconducting magnetic bearing B that supports the shaft 10 is also the power supplied to the superconducting motor system 1 via the power transmission cable C and used.

[0044] Thus, in the superconducting motor system 1, the superconducting stator coil 50, the superconducting thrust bearing B1, and the superconducting radial bearing B2 are housed in the refrigerant space R2 formed between the inner housing 30 and the outer housing 40. That is, the superconducting stator coil 50, the superconducting thrust bearing B1, and the superconducting radial bearing B2 are immersed in the liquid hydrogen LH2 housed in the refrigerant space R2. The superconducting motor system 1 can cool the superconducting stator coil 50 for rotating the shaft 10, the superconducting thrust bearing B1, and the superconducting radial bearing B2 that support the shaft 10 with the liquid hydrogen LH2 housed in the refrigerant space R2. Thereby, the superconducting motor system 1 can efficiently rotate the shaft 10 by the interaction of the magnetic fields in the superconducting stator coil 50 and the rotor 20. Also, the superconducting motor system 1 can support the shaft 10 in a non-contact manner by the superconducting thrust bearing B1 and the superconducting radial bearing B2, which are superconducting magnetic bearings B. Thereby, the superconducting motor system 1 can support the shaft in a state of high rotational efficiency by the superconducting magnetic bearing B. Thus, the superconducting motor system 1 can obtain higher rotational efficiency.

[0045] Further, the superconducting motor system 1 uses a superconducting radial bearing B2 as a bearing that supports the shaft 10 in the radial direction. Thereby, the superconducting motor system 1 can improve the load capacity of the support in the radial direction of the shaft 10 (the performance of supporting the shaft 10) by using the superconducting radial bearing B2, as compared with a normal magnetic bearing that does not use superconducting technology.

[0046] The superconducting motor system 1 includes a vacuum pump 60 that evacuates the inside of the inner housing 30 (rotor chamber R1). Here, the first portion 10a of the shaft 10 and the rotor 20 attached to the first portion 10a are accommodated in the inner housing 30. That is, in the superconducting motor system 1, the rotating part (the rotating rotor 20 and the first portion 10a of the shaft 10) is accommodated in the inner housing 30. Thereby, the superconducting motor system 1 can reduce the windage loss generated by the friction between the gas and the rotating part by evacuating the inside of the inner housing 30 in which the rotating part is accommodated by the vacuum pump 60. Thus, the superconducting motor system 1 can obtain a higher rotation efficiency by evacuating the inside of the inner housing 30.

[0047] Further, by making the inside of the rotor chamber R1 that houses the rotor 20 into a decompressed state (vacuum state), the rotor 20 can be thermally insulated from the liquid hydrogen LH2 housed in the refrigerant space R2. Thereby, in the superconducting motor system 1, the rotor 20 can be protected from the low-temperature environment.

[0048] The superconducting motor system 1 includes a superconducting thrust bearing B1 and a superconducting radial bearing B2 as superconducting magnetic bearings that support the shaft 10. In this case, the superconducting motor system 1 can efficiently support the shaft 10 in both the axial direction and the radial direction by using the superconducting thrust bearing B1 and the superconducting radial bearing B2.

[0049] The magnet provided on the rotor 20 forms a flux concentration type field magnet. In this case, the superconducting motor system 1 can obtain a higher rotation efficiency by using the rotor 20 in which the magnet is a flux concentration type field magnet.

[0050] The outer casing 40 of the superconducting motor system 1 constitutes a reserve tank located in the middle of the piping L for liquid hydrogen LH2 from the main tank 2 to the fuel cell 3. For example, if an imbalance occurs in the liquid hydrogen LH2 within the main tank 2, it is conceivable that the liquid hydrogen LH2 may not be properly supplied from the main tank 2 to the fuel cell 3 (e.g., the supply may be interrupted). Therefore, in the superconducting motor system 1, the outer casing 40, which forms a refrigerant space R2 for cooling the superconducting stator coil 50 and the like, functions as a reserve tank, allowing for a more appropriate supply of liquid hydrogen LH2 to the fuel cell 3. Furthermore, the pressure inside the main tank 2 is adjusted to a high pressure in order to pump the liquid hydrogen LH2. As a result, the liquid hydrogen LH2 remaining in the main tank 2 is pumped to the superconducting motor system 1 by the siphon principle due to the pressure inside the main tank 2. This allows the superconducting motor system 1 to cool the superconducting stator coil 50 and the superconducting magnetic bearing B by receiving a supply of liquid hydrogen LH2 from the main tank 2, even when the amount of liquid hydrogen LH2 in the main tank 2 decreases.

[0051] The power transmission cable C, which supplies power generated by the fuel cell 3 to the superconducting stator coil 50 and superconducting magnetic bearing B of the superconducting motor system 1, is located within the second piping section L2. In this case, the power transmission cable C can be cooled by the liquid hydrogen LH2 supplied from the outer housing 40 of the superconducting motor system 1 to the fuel cell 3. This improves the power transmission efficiency in the power transmission cable C. At least one of the superconducting stator coil 50 and superconducting magnetic bearing B of the superconducting motor system 1 is powered by the power transmission cable C, which is made of a superconducting material.

[0052] (First Modification of the First Embodiment) A first modification of the superconducting motor system 1 according to the first embodiment will be described. In the following description of the modification, the differences from the superconducting motor system 1 according to the first embodiment will be explained in detail. As shown in Figure 4, the superconducting motor system 1A according to this modification is equipped with a thrust disk 12 instead of the thrust disk 11 of the superconducting motor system 1 according to the first embodiment. The superconducting motor system 1A according to this modification does not have the vacuum pump 60 of the superconducting motor system 1 according to the first embodiment. In other words, in this modification, the rotating chamber R1 is in communication with the outside space via the outlet R1a.

[0053] The thrust disk 12 is attached to the shaft 10. The thrust disk 12 rotates integrally with the shaft 10. The thrust disk 12 is sandwiched in the axial direction by a pair of superconducting thrust bearings B1. The superconducting thrust bearings B1 support the shaft 10 in the axial direction by magnetic force, which attracts the thrust disk 12 to one side and the other side in the axial direction.

[0054] As shown in Figures 5(a) and 5(b), the thrust disk 12 comprises a pressure-reducing blade 12a and a disk body 12b. For example, the disk body 12b is annular in shape. The pressure-reducing blade 12a is located inside the disk body 12b.

[0055] The pressure-reducing blade 12a rotates around the shaft 10 as the shaft 10 rotates. This rotation causes the pressure-reducing blade 12a to blow air (gas) from the rotating chamber R1 towards the outlet R1a. The air sent to the outlet R1a is then discharged out of the rotating chamber R1 through the outlet R1a. As a result, the pressure-reducing blade 12a can reduce the pressure inside the rotating chamber R1. In this way, the thrust disc 12 equipped with the pressure-reducing blade 12a functions as a pressure-reducing mechanism that reduces the pressure inside the inner housing 30 (rotating chamber R1).

[0056] In this case, in the superconducting motor system 1A, the thrust disk 12 equipped with a pressure-reducing blade 12a is attached to the first portion 10a of the shaft 10 and rotates together with the shaft 10. The superconducting motor system 1A can reduce the pressure inside the inner housing 30 by the rotation of the pressure-reducing blade 12a that rotates together with the shaft 10. As a result, the superconducting motor system 1A can reduce windage losses and obtain even higher rotational efficiency by reducing the pressure inside the inner housing 30.

[0057] (Second Modification of the First Embodiment) A second modification of the superconducting motor system 1 according to the first embodiment will be described. As shown in Figure 6, the superconducting motor system 1B according to this modification is equipped with an impeller-type thrust disk 13 instead of the thrust disk 11 of the superconducting motor system 1 according to the first embodiment. The superconducting motor system 1B according to this modification does not have a vacuum pump 60, similar to the superconducting motor system 1A according to the first modification of the first embodiment. In other words, in this modification, the rotating chamber R1 is in communication with the outside space via the outlet R1a. Note that in the superconducting motor system 1B, the outlet R1a of the rotating chamber R1 is provided at a different position than in the superconducting motor system 1A according to the first modification. The outlet R1a is in communication with the space around the outer edge of the impeller-type thrust disk 13 inside the rotating chamber R1 via the air guide pipe R1b.

[0058] The impeller-type thrust disc 13 is attached to the shaft 10. The impeller-type thrust disc 13 rotates integrally with the shaft 10. The impeller-type thrust disc 13 is sandwiched in the axial direction by a pair of superconducting thrust bearings B1. The superconducting thrust bearings B1 support the shaft 10 in the axial direction by magnetic force, which attracts the impeller-type thrust disc 13 to one and the other side in the axial direction.

[0059] The impeller-type thrust disc 13 is equipped with an impeller 13a. The impeller 13a rotates around the shaft 10 as the shaft 10 rotates. This rotation causes the impeller 13a to blow air (gas) around the shaft 10 radially outward within the rotating chamber R1. The air blown by the impeller 13a is discharged outside the rotating chamber R1 through the outlet R1a via the air guide pipe R1b. In this way, the impeller 13a blows air from within the rotating chamber R1 towards the outlet R1a. As a result, the impeller 13a can reduce the pressure inside the rotating chamber R1. In other words, the impeller-type thrust disc 13 equipped with the impeller 13a functions as a pressure reducing mechanism that reduces the pressure inside the inner housing 30 (rotating chamber R1).

[0060] Here, the impeller 13a is provided on the surface of the impeller-type thrust disc 13 facing the rotor 20. As described above, the impeller 13a blows air around the shaft 10 radially outward. As a result, in the space around the impeller-type thrust disc 13 within the rotating chamber R1, the pressure (air pressure) in the space on the side where the impeller 13a is provided (the rotor 20 side) becomes lower. Conversely, the pressure in the space on the opposite side of where the impeller 13a is provided becomes relatively higher. This causes a force F2 to be applied to the impeller-type thrust disc 13 toward the rotor 20. In other words, a force F2 is applied to the shaft 10 to which the impeller-type thrust disc 13 is attached as the impeller-type thrust disc 13 rotates.

[0061] Furthermore, in this modified example, the main blade M generates a force (thrust force) that pulls the entire superconducting motor system 1B toward the opposite side of the rotor 20 as the shaft 10 rotates. In other words, a force F1 is applied to the shaft 10 to which the main blade M is attached as the main blade M rotates. Thus, the force F1 applied by the main blade M to the shaft 10 and the force F2 applied by the impeller-type thrust disc 13 to the shaft 10 are in opposite directions.

[0062] Even in this case, the superconducting motor system 1B can reduce windage losses and achieve even higher rotational efficiency by reducing the pressure inside the inner housing 30 using the impeller-type thrust disk 13.

[0063] Furthermore, the impeller 13a of the impeller-type thrust disc 13 is mounted in a direction such that the direction of the thrust force (force F2) applied to the shaft 10 by the rotation of the impeller-type thrust disc 13 (impeller 13a) and the direction of the thrust force (force F1) applied to the shaft 10 by the rotation of the main blade M are opposite to each other. In this case, the superconducting motor system 1B can cancel out or reduce the thrust force (force F1) applied to the shaft 10 by the rotation of the main blade M with the thrust force (force F2) generated on the shaft 10 by the rotation of the impeller-type thrust disc 13. This makes it easy for the superconducting motor system 1B to support the shaft 10 in the thrust direction. Here, the superconducting motor system 1B can reduce the load on the superconducting thrust bearing B1.

[0064] In the example shown in Figure 6, the main blade M and the impeller-type thrust disc 13 were mounted on the same side (left side in Figure 6) relative to the rotor 20 on the shaft 10. However, the system is not limited to this, and as in the superconducting motor system 1C shown in Figure 7, the main blade M and the impeller-type thrust disc 13 may be mounted on the shaft 10 so as to sandwich the rotor 20. Even in this case, the impeller 13a of the impeller-type thrust disc 13 is mounted in a direction such that the direction of the thrust force (force F2) applied to the shaft 10 by the rotation of the impeller-type thrust disc 13 (impeller 13a) and the direction of the thrust force (force F1) applied to the shaft 10 by the rotation of the main blade M are opposite to each other. As a result, the superconducting motor system 1C shown in Figure 7 can easily support the shaft 10 in the thrust direction, similar to the superconducting motor system 1B shown in Figure 6.

[0065] (Second Embodiment) A second embodiment of the superconducting motor system will be described. The superconducting motor system in this embodiment constitutes a radial gap type motor with an outer rotor. As shown in Figure 8, the superconducting motor system 1D according to this embodiment is composed of a shaft 10, a rotor 20D, an inner housing (first housing, box) 30D, an outer housing (second housing, box) 40D, and a superconducting stator coil 50.

[0066] The inner housing 30D forms a rotating chamber R1 on its interior that houses a part of the shaft 10 and a rotating body such as the rotor 20D. In this embodiment, the inner housing 30D is made of a magnetically permeable material.

[0067] The rotor 20D has a cylindrical shape that surrounds the shaft 10. The rotor 20D is attached to the shaft 10 by a stay 14 so as to surround the shaft 10. In other words, the first portion 10a of the shaft 10 passes inside the rotor 20D. The stay 14 is attached to the first portion 10a of the shaft 10. The rotor 20D is attached to the first portion 10a of the shaft 10 by the stay 14. The magnets provided on the rotor 20D may be permanent magnets, similar to the rotor 20 in the first embodiment, and may be arranged in a Halbach array. The rotor 20D may also be configured to include windings that generate a magnetic field.

[0068] The outer housing 40D houses the inner housing 30D. The outer housing 40D forms a refrigerant space R2 between itself and the inner housing 30D that can accommodate a refrigerant. The outer housing 40D of the superconducting motor system 1D, like the outer housing 40 in the first embodiment, constitutes a reserve tank located in the middle of the piping L for liquid hydrogen LH2 from the main tank 2 to the fuel cell 3. In this embodiment, at least the inner housing 30D surrounding the shaft 10 and rotor 20D is permeable to magnetism. That is, in the box formed by the inner housing 30D and the outer housing 40D, the portion facing the shaft 10 (the inner housing 30D of the inner housing 30D and outer housing 40D) is permeable to magnetism.

[0069] The superconducting stator coil 50 is housed in the coolant space R2. The superconducting stator coil 50 is positioned inside the cylindrical rotor 20D. In the radial direction, the superconducting stator coil 50 faces the rotor 20D with the inner housing 30D in between.

[0070] Furthermore, the superconducting motor system 1D includes a superconducting magnetic bearing B that rotatably supports the shaft 10. In this embodiment, the superconducting magnetic bearing B includes a superconducting radial bearing B2. The superconducting radial bearing B2 faces the outer circumferential surface of the first portion 10a of the shaft 10 in the radial direction, with the inner housing 30D in between. In addition, the superconducting magnetic bearing B in the superconducting motor system 1D may also include a superconducting thrust bearing, similar to the superconducting motor system 1 in the first embodiment. In this case, a thrust disk supported in the axial direction by the superconducting thrust bearing may be attached to the shaft 10.

[0071] In this superconducting motor system 1D, a magnetic field is formed when current is supplied to the superconducting stator coil 50. The magnetic field generated by the superconducting stator coil 50 interacts with the magnetic field of the rotor 20D, generating a rotational force in the rotor 20D, which in turn causes the shaft 10 to which the rotor 20D is attached to rotate. The power supplied to the superconducting stator coil 50 is generated by the fuel cell 3 and supplied to the superconducting motor system 1D via the power transmission cable C, similar to the superconducting motor system 1 according to the first embodiment.

[0072] Thus, in the superconducting motor system 1D, the superconducting stator coil 50 and the superconducting radial bearing B2, which is a superconducting magnetic bearing B, are housed in a coolant space R2 formed between the inner housing 30D and the outer housing 40D. As a result, the superconducting motor system 1D can achieve higher rotational efficiency, similar to the superconducting motor system 1 according to the first embodiment.

[0073] In addition, the superconducting motor system 1D according to this embodiment may also be provided with a pressure reduction mechanism such as a vacuum pump for reducing the pressure inside the inner housing 30D, a touchdown bearing G for supporting the shaft 10, and the like, similar to the first embodiment and its various modifications.

[0074] (Third Embodiment) A third embodiment of the superconducting motor system will be described. The superconducting motor system in this embodiment constitutes an axial gap type motor. As shown in Figure 9, the superconducting motor system 1E according to this embodiment is composed of a shaft 10, a rotor 21E, a rotor 22E, an inner housing (first housing, box) 30E, an outer housing (second housing, box) 40E, and a superconducting stator coil 50E.

[0075] The inner housing 30E forms a rotating chamber R1 on its interior that houses a part of the shaft 10 and rotating bodies such as rotors 21E and 22E. In this embodiment, the inner housing 30E is made of a magnetically permeable material.

[0076] Rotors 21E and 22E are each attached to the first portion 10a of the shaft 10 at a predetermined distance apart from each other in the axial direction. Rotors 21E and 22E have a disc shape that extends radially outward from the shaft 10. Rotors 21E and 22E may be configured to include permanent magnets, similar to rotor 20 in the first embodiment, or they may be configured to include windings that generate a magnetic field.

[0077] The outer housing 40E houses the inner housing 30E. The outer housing 40E forms a refrigerant space R2 between itself and the inner housing 30E that can accommodate a refrigerant. The refrigerant space R2 formed by the inner housing 30E and the outer housing 40E is also formed between the rotor 21E and the rotor 22E. The outer housing 40E of the superconducting motor system 1E, like the outer housing 40 in the first embodiment, constitutes a reserve tank provided in the middle of the piping L for liquid hydrogen LH2 from the main tank 2 to the fuel cell 3. In this embodiment, at least the inner housing 30E surrounding the shaft 10 and the rotors 21E and 22E is permeable to magnetism. That is, in the box formed by the inner housing 30E and the outer housing 40E, the portion facing the shaft 10 (the inner housing 30E of the inner housing 30E and the outer housing 40E) is permeable to magnetism.

[0078] The superconducting stator coil 50E is housed within the coolant space R2. The superconducting stator coil 50E is positioned between the rotor 21E and the rotor 22E within the coolant space R2. In the axial direction, the superconducting stator coil 50E faces the rotor 21E and the rotor 22E, respectively, with the inner housing 30E in between.

[0079] Furthermore, the superconducting motor system 1E includes a superconducting magnetic bearing B that rotatably supports the shaft 10. In this embodiment, the superconducting magnetic bearing B includes a superconducting radial bearing B2. The superconducting radial bearing B2 faces the outer circumferential surface of the first portion 10a of the shaft 10 in the radial direction, with the inner housing 30E in between. In addition, the superconducting magnetic bearing B in the superconducting motor system 1E may also include a superconducting thrust bearing, similar to the superconducting motor system 1 in the first embodiment. In this case, a thrust disk supported in the axial direction by the superconducting thrust bearing may be attached to the shaft 10.

[0080] In this superconducting motor system 1E, a magnetic field is formed when current is supplied to the superconducting stator coil 50E. The magnetic field generated by the superconducting stator coil 50E interacts with the magnetic fields of the rotors 21E and 22E, generating a rotational force in the rotors 21E and 22E, causing the shaft 10 to which the rotors 21E and 22E are attached to rotate. The power supplied to the superconducting stator coil 50E is generated by the fuel cell 3 and supplied to the superconducting motor system 1E via the power transmission cable C, similar to the superconducting motor system 1 according to the first embodiment.

[0081] Thus, in the superconducting motor system 1E, the superconducting stator coil 50E and the superconducting radial bearing B2, which is a superconducting magnetic bearing B, are housed in a coolant space R2 formed between the inner housing 30E and the outer housing 40E. As a result, the superconducting motor system 1E can achieve higher rotational efficiency, similar to the superconducting motor system 1 according to the first embodiment.

[0082] In addition, the superconducting motor system 1E according to this embodiment may also be provided with a pressure reduction mechanism such as a vacuum pump for reducing the pressure inside the inner housing 30E, a touchdown bearing for supporting the shaft 10, and the like, similar to the first embodiment and its various modifications.

[0083] (Modification of the Third Embodiment) A modification of the superconducting motor system 1E according to the third embodiment will now be described. As shown in Figure 10, the superconducting motor system 1F according to this modification is equipped with a rotor 20F in place of the rotors 21E and 22E of the superconducting motor system 1E according to the third embodiment. Furthermore, the superconducting motor system 1F according to this modification is equipped with superconducting stator coils 51F and 52F in place of the superconducting stator coil 50E of the superconducting motor system 1E according to the third embodiment.

[0084] The rotor 20F is attached to the first portion 10a of the shaft 10. The rotor 20F has a disc shape that extends radially outward from the shaft 10. The rotor 20F may be configured to include permanent magnets, similar to the rotor 20 in the first embodiment, or it may be configured to include windings that generate a magnetic field.

[0085] The superconducting stator coils 51F and 52F are housed in a coolant space R2 formed by the inner housing 30E and the outer housing 40E. Within the coolant space R2, the superconducting stator coils 51F and 52F are positioned to sandwich the rotor 20F in the axial direction. In other words, the rotor 20F is positioned between the superconducting stator coils 51F and 52F in the axial direction. The superconducting stator coils 51F and 52F face the rotor 20F in the axial direction, with the inner housing 30E in between.

[0086] Even in this case, the superconducting motor system 1F can achieve higher rotational efficiency, similar to the superconducting motor system 1E according to the third embodiment.

[0087] (Fourth Embodiment) A fourth embodiment of the superconducting motor system will be described. The superconducting motor system in this embodiment differs from the examples described above in the configuration of the coolant space surrounding the shaft. As shown in Figures 11(a) and 11(b), the superconducting motor system 1G according to this embodiment is composed of a shaft 10, a rotor 20, a superconducting stator coil 51, a superconducting stator coil 52, a housing 71, and a housing 72.

[0088] The boxes 71 and 72 are each positioned around the shaft 10. Each box 71 and 72 has magnetic permeability in at least the portion facing the shaft 10. Each box 71 and 72 forms a refrigerant space R2 capable of containing liquid hydrogen LH2 (refrigerant). In this embodiment, the shaft 10 is surrounded by the boxes 71 and 72 over its entire circumference (almost entirely). Here, box 71 surrounds approximately half of the circumference of the outer surface of the shaft 10. Box 72 surrounds approximately half of the circumference of the outer surface of the shaft 10.

[0089] The rotor 20 is mounted on the shaft 10. The housing 71 covers the portion of the shaft 10 on which the rotor 20 is mounted and the surrounding portion of the shaft 10 on which the rotor 20 is mounted. Similarly, the housing 72 covers the portion of the shaft 10 on which the rotor 20 is mounted and the surrounding portion of the shaft 10 on which the rotor 20 is mounted.

[0090] The superconducting stator coil 51 is housed in a coolant space R2 formed within the casing 71. The superconducting stator coil 51 faces the rotor 20 in the radial direction, with the wall of the casing 71 (the part of the casing 71 facing the outer surface of the rotor 20) in between. For example, the superconducting stator coil 51 surrounds approximately half of the circumferential surface of the rotor 20. The superconducting stator coil 52 is housed in a coolant space R2 formed within the casing 72. The superconducting stator coil 52 faces the rotor 20 in the radial direction, with the wall of the casing 72 (the part of the casing 72 facing the outer surface of the shaft 10) in between. For example, the superconducting stator coil 52 surrounds approximately half of the circumferential surface of the rotor 20.

[0091] Furthermore, the superconducting motor system 1G includes a superconducting magnetic bearing B that rotatably supports the shaft 10. In this embodiment, the superconducting magnetic bearing B includes a superconducting radial bearing B21 and a superconducting radial bearing B22. The superconducting radial bearing B21 is housed in the coolant space R2 of the housing 71. In the radial direction, the superconducting radial bearing B21 faces the outer surface of the shaft 10, with the wall portion of the housing 71 (the portion of the housing 71 facing the outer surface of the shaft 10) in between. The superconducting radial bearing B22 is housed in the coolant space R2 of the housing 72. In the radial direction, the superconducting radial bearing B22 faces the outer surface of the shaft 10, with the wall portion of the housing 72 (the portion of the housing 72 facing the outer surface of the shaft 10) in between. Note that in the superconducting motor system 1G, the superconducting magnetic bearing B may also include a superconducting thrust bearing, similar to the superconducting motor system 1 according to the first embodiment. In this case, the shaft 10 may be fitted with a thrust disc that is supported in the axial direction by a superconducting thrust bearing.

[0092] Thus, in the superconducting motor system 1G, the superconducting stator coils 51 and 52 and the superconducting radial bearings B21 and B22 are housed in a coolant space R2 formed inside the housings 71 and 72. As a result, the superconducting motor system 1G can cool the superconducting stator coils 51 and 52 that rotate the shaft 10, and the superconducting radial bearings B21 and B22 that support the shaft 10, with liquid hydrogen LH2 housed in the coolant space R2. This allows the superconducting motor system 1G to achieve higher rotational efficiency.

[0093] In the superconducting motor system 1G, the shaft 10 was surrounded by two boxes, boxes 71 and 72. However, the superconducting motor system is not limited to this, and the shaft 10 may be surrounded by three or more boxes.

[0094] While embodiments and variations of the present disclosure have been described above, the present disclosure is not limited to the embodiments and variations described above. For example, the superconducting motor system described above may be provided with at least one of a superconducting thrust bearing B1 and a superconducting radial bearing B2, which are provided as superconducting magnetic bearings B. Alternatively, the superconducting motor system may be provided with at least one superconducting magnetic bearing B. For example, the superconducting motor system described above may include a conventional magnetic bearing that does not use superconducting technology and a superconducting magnetic bearing B. In this case, for example, the superconducting motor system described above may have either a thrust bearing or a radial bearing that is a superconducting magnetic bearing, and the other being a conventional magnetic bearing. Furthermore, a plurality of thrust bearings may include both conventional magnetic bearings that do not use superconducting technology and superconducting magnetic bearings. Similarly, a plurality of radial bearings may include both conventional magnetic bearings that do not use superconducting technology and superconducting magnetic bearings.

[0095] The example given is that the liquid hydrogen LH2 in the main tank 2 is supplied to the fuel cell 3 or a hydrogen combustion jet engine via a superconducting motor system. The receiving device to which the liquid hydrogen LH2 is supplied is not limited to the fuel cell 3 described above. Various devices can be used as the receiving device for the liquid hydrogen LH2. Furthermore, the propulsion unit 100 is not limited to being applied to an airplane. For example, the propulsion unit 100 can be applied to various mobile vehicles such as ships and automobiles.

[0096] The gist of this disclosure is as follows: [1] A superconducting motor system comprising: a shaft; a housing disposed around the shaft and forming a refrigerant space inside which a refrigerant can be contained, and the portion facing the shaft being magnetically permeable; a rotor provided on the shaft; a superconducting stator coil housed in the refrigerant space and disposed around the rotor; and a superconducting magnetic bearing housed in the refrigerant space and having a superconducting coil that supports the shaft. [2] The superconducting motor system according to [1], wherein the housing comprises: a first housing that houses a first portion of the shaft and is magnetically permeable; and a second housing that houses the first housing and forms the refrigerant space between itself and the first housing, and the rotor is provided on the first portion of the shaft. [3] The superconducting motor system according to [2], further comprising: a pressure reducing mechanism for reducing the pressure inside the first housing. [4] The superconducting motor system according to [3], wherein the pressure reducing mechanism has a pressure reducing blade attached to the first portion of the shaft, and the rotation of the pressure reducing blade discharges gas inside the first housing to the outside of the first housing. [5] The superconducting motor system according to [4], wherein a main blade is attached to a second portion of the shaft that extends outside the first housing, and the pressure reducing blade is mounted in a direction such that the direction of the thrust force applied to the shaft by the rotation of the pressure reducing blade and the direction of the thrust force applied to the shaft by the rotation of the main blade are in opposite directions. [6] The superconducting motor system according to any one of [1] to [5], wherein the superconducting magnetic bearing includes at least one of a superconducting thrust bearing that supports the shaft in the axial direction and a superconducting radial bearing that supports the shaft in the radial direction. [7] The superconducting motor system according to any one of [1] to [6], wherein the magnet provided on the rotor is a magnetic flux concentrated field. [8] The superconducting motor system according to [2], wherein the refrigerant is liquid hydrogen, and the second housing consists of a reserve tank provided in the middle of the supply path of liquid hydrogen from a main tank that stores the liquid hydrogen to a supply destination device.[9] The superconducting motor system according to [8], wherein the supply destination device is a fuel cell, a superconducting power transmission cable for transmitting power generated by the fuel cell is arranged in the supply piping that forms the supply path of liquid hydrogen from the second housing to the fuel cell, and at least one of the superconducting stator coil and the superconducting coil is supplied with power from the fuel cell via the superconducting power transmission cable.

[0097] 1, 1A-1G Superconducting motor system 2 Main tank 3 Fuel cell (supply destination device) 10 Shaft 10a First part 10b Second part 12 Thrust disk (pressure reduction mechanism) 12a Pressure reduction blade (pressure reduction mechanism) 13 Impeller-type thrust disk (pressure reduction mechanism) 20, 20D, 20F, 21E, 22E Rotor 30, 30D, 30E Inner housing (first housing, box) 40, 40D, 40E Outer housing (second housing, reserve tank, box) 50, 50E, 51F, 52F Superconducting stator coil 60 Vacuum pump (pressure reduction mechanism) 70-72 Box B Superconducting magnetic bearing B1 Superconducting thrust bearing B2, B21, B22 Superconducting radial bearing M Main blade L Piping (supply route) L2 Second piping section (supply piping): LH2 liquid hydrogen, R2 refrigerant space.

Claims

1. A superconducting motor system comprising: a shaft; a box body disposed around the shaft, forming a refrigerant space capable of containing a refrigerant, and having a portion facing the shaft that is magnetically permeable; a rotor provided on the shaft; a superconducting stator coil housed in the refrigerant space and disposed around the rotor; and a superconducting magnetic bearing housed in the refrigerant space and having a superconducting coil that supports the shaft.

2. The superconducting motor system according to claim 1, wherein the housing comprises a first housing that houses a first portion of the shaft and is permeable to magnetism, and a second housing that houses the first housing and forms the coolant space between itself and the first housing, and the rotor is provided on the first portion of the shaft.

3. The superconducting motor system according to claim 2, further comprising a pressure reduction mechanism for reducing the pressure inside the first housing.

4. The superconducting motor system according to claim 3, wherein the pressure reduction mechanism has a pressure reduction blade attached to the first portion of the shaft, and the rotation of the pressure reduction blade discharges the gas inside the first housing to the outside of the first housing.

5. The superconducting motor system according to claim 4, wherein a main blade is attached to a second portion of the shaft that extends outside the first housing, and the depressurizing blade is mounted in a direction such that the direction of the thrust force applied to the shaft by the rotation of the depressurizing blade and the direction of the thrust force applied to the shaft by the rotation of the main blade are in opposite directions.

6. The superconducting motor system according to claim 1, wherein the superconducting magnetic bearing includes at least one of a superconducting thrust bearing that supports the shaft in the axial direction and a superconducting radial bearing that supports the shaft in the radial direction.

7. The superconducting motor system according to any one of claims 1 to 6, wherein the magnet provided on the rotor is a magnetic flux concentrated field.

8. The superconducting motor system according to claim 2, wherein the refrigerant is liquid hydrogen, and the second housing is composed of a reserve tank provided in the middle of the supply path of the liquid hydrogen from a main tank for storing the liquid hydrogen to a supply destination device.

9. The superconducting motor system according to claim 8, wherein the supply destination device is a fuel cell, a superconducting power transmission cable for transmitting power generated by the fuel cell is arranged in the supply piping that forms the supply path of the liquid hydrogen from the second housing to the fuel cell, and at least one of the superconducting stator coil and the superconducting coil is supplied with power from the fuel cell via the superconducting power transmission cable.

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