Liquid hydrogen tank

Abstract

This provides a liquid hydrogen tank that increases the liquid hydrogen storage capacity while improving durability. [Solution] A liquid hydrogen tank 10, which is capable of storing liquid hydrogen inside, comprises a pair of end plate sections 11 arranged facing each other and a body section 12 connecting the outer edges of the pair of end plate sections 11. The outer edges of the end plate sections 11 are composed of a first curved section 13 consisting only of curves, a second curved section 14 consisting only of curves, and a third curved section 15 and a fourth curved section 16 connected to the first curved section 13 and the second curved section 14, each consisting only of curves with a greater curvature than the first curved section 13 and the second curved section 14. A reinforcing section 50 is formed in at least one region of the first curved section 13 and the second curved section 14 of the end plate section 11, projecting inward.

Description

Technical Field

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[0001] The present invention relates to a liquid hydrogen tank capable of storing liquid hydrogen.

Background Art

[0002] Conventionally, an in-vehicle liquid hydrogen tank capable of storing hydrogen in a liquid state has been known. For example, Patent Document 1 discloses a rice-bag-shaped inner tank having a cylindrical body portion for storing liquid hydrogen and end plates for closing both axial ends of the body portion, an outer tank for housing the inner tank, and a heat insulating material disposed in a heat insulating gap, which is a gap between the inner tank and the outer tank, for holding the inner tank in a state of being separated from the inner surface of the outer tank. The heat insulating gap has a vacuum region not filled with the heat insulating material and a region filled with the heat insulating material where the inner tank is surface-supported by the heat insulating material. An in-vehicle liquid hydrogen tank is disclosed. ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ Incidentally, in the technology described in Patent Document 1, the cylindrical shape of the body creates a large dead space within the installation area. On the other hand, in the technology described in Non-Patent Document 1, although the liquid hydrogen storage capacity is increased, the uniformity of the stress distribution decreases in an elliptical cylindrical tank, resulting in a decrease in pressure resistance. As a result, the durability of the on-board liquid hydrogen tank is reduced compared to the case where the body is cylindrical.

[0007] The present invention aims to solve the above-mentioned problems and to provide a liquid hydrogen tank that increases the liquid hydrogen storage capacity while improving durability. [Means for solving the problem]

[0008] A liquid hydrogen tank according to the first aspect of the present invention for solving the above problems comprises a pair of end plates arranged facing each other, and a body connecting the outer edges of the pair of end plates, and is an on-board liquid hydrogen tank capable of storing liquid hydrogen inside, wherein the outer edge of the end plate is composed of a first curved section consisting only of curves, a second curved section consisting only of curves, and a third curved section and a fourth curved section connected to the first and second curved sections and consisting only of curves with a greater curvature than the first and second curved sections, and a reinforcing section is formed in the region of at least one of the first and second curved sections of the end plate that protrudes inward.

[0009] In the liquid hydrogen tank according to the first aspect of the present invention, the outer edge of the end plate is composed of a first curved section consisting only of a curve, a second curved section consisting only of a curve, and a third and fourth curved sections connected to the first and second curved sections, each having a greater curvature than the first and second curved sections. Therefore, the curvature of each curved section can be adjusted to match the shape of the installation space when mounted in a vehicle. As a result, a liquid hydrogen tank with an increased liquid hydrogen capacity can be installed without generating large dead spaces.

[0010] Furthermore, by using a configuration that connects only curves, it is possible to reduce variations in stress distribution on the inner surface of the liquid hydrogen tank.

[0011] The first and second curved sections have a smaller curvature than the third and fourth curved sections, and therefore have lower rigidity compared to the regions of the third and fourth curved sections. In the liquid hydrogen tank according to the first curved surface of the present invention, a reinforcing portion is formed in at least one region of the first and second curved sections of the end plate, projecting inward. This increases the rigidity of the regions of the first and second curved sections. As a result, the pressure resistance is increased, improving the durability of the liquid hydrogen tank.

[0012] Furthermore, since the pressure resistance can be increased by forming a reinforced section, the mass of the liquid hydrogen tank can be reduced compared to the case where the thickness of the material constituting the liquid hydrogen tank is partially increased to achieve the same pressure resistance. Furthermore, measures to increase the pressure resistance of liquid hydrogen tanks can be easily implemented.

[0013] Furthermore, since the reinforcing portion is formed to protrude inward, it prevents deformation and damage to the liquid hydrogen tank, and also prevents the reinforcing portion from obstructing the outer tank, which is positioned outside the liquid hydrogen tank via an insulating area to enable stable storage of liquid hydrogen.

[0014] A liquid hydrogen tank according to a second aspect of the present invention is a liquid hydrogen tank in which, in the first aspect, the end plate portion is composed of a flange portion connected to the end of the body portion and a curved surface portion continuous with the flange portion, the axial cross-section of the body portion being a curved shape that is convex in the direction away from the flange portion, and the reinforcing portion is formed on the curved surface portion side of the continuous portion between the flange portion and the curved surface portion.

[0015] In the liquid hydrogen tank according to the second aspect of the present invention, the end plate portion is composed of a flange portion connected to the end of the body portion and a curved surface portion that is continuous with the flange portion and whose axial cross-section of the body portion is a curved shape that is convex in the direction away from the flange portion. For example, when connecting the end plate portion and the body portion by welding, welding is easier compared to welding the body portion and the curved surface portion. Furthermore, deformation of the end of the curved surface portion can be prevented, thus preventing a decrease in the durability of the liquid hydrogen tank due to such deformation.

[0016] Furthermore, since the curved portion is composed of a convex curve in the axial direction of the body portion, away from the flange portion, it is possible to reduce variations in stress distribution in the axial direction of the body portion of the curved portion.

[0017] Furthermore, since the reinforcing portion is formed on the curved surface side of the continuum between the flange and the curved surface, stress concentration in the curved surface can be avoided in the cross-section perpendicular to the axial direction of the body, compared to when the reinforcing portion is formed at the continuum between the flange and the curved surface. As a result, the pressure resistance strength is increased, and the durability of the liquid hydrogen tank can be improved.

[0018] A liquid hydrogen tank according to a third aspect of the present invention is a liquid hydrogen tank in which, in the first and second aspects, the reinforcing portion extends to a part of at least one of the regions of the third curved portion and the fourth curved portion.

[0019] If the reinforcing portion is formed within the first and second curved surfaces, stress concentration will occur at the end of the reinforcing portion, which may reduce the durability of the first and second curved surfaces near the end of the reinforcing portion.

[0020] In the liquid hydrogen tank according to the third aspect of the present invention, the reinforcing portion extends to a part of at least one of the third curved portion and the fourth curved portion. By forming the end of the reinforcing portion where stress concentration occurs within the more robust third and fourth curved portions, the durability of the liquid hydrogen tank can be further improved.

[0021] The liquid hydrogen tank according to the fourth aspect of the present invention is the liquid hydrogen tank in which, in the first to third aspects, the reinforcing portion is formed to protrude inwardly also in the body portion.

[0022] In the liquid hydrogen tank according to the fourth aspect of the present invention, since the reinforcing portion is formed to protrude inwardly also in the body portion, the pressure resistance of the body portion can be increased. As a result, the durability of the liquid hydrogen tank can be further improved.

[0023] Also, since the reinforcing portion is formed to protrude inwardly and extend in the body portion, it is possible to prevent deformation and damage in the body portion of the liquid hydrogen tank, and to prevent the reinforcing portion from becoming an obstacle to the outer tank disposed outside the liquid hydrogen tank through the heat insulating region in order to stably store liquid hydrogen.

Effect of the Invention

[0024] The liquid hydrogen tank is an in-vehicle liquid hydrogen tank that includes a pair of end plates disposed to face each other and a body portion connecting the outer peripheral edges of the pair of end plates, and is capable of storing liquid hydrogen inside. The outer peripheral edge of the end plate portion is composed of a first curved portion consisting only of a curve, a second curved portion consisting only of a curve, a third curved portion and a fourth curved portion that are connected to the first curved portion and the second curved portion and consist only of a curve having a larger curvature than the first curved portion and the second curved portion. Since a reinforcing portion that protrudes inwardly and extends is formed in at least one region of the first curved portion and the second curved portion, the outer peripheral edge of the end plate portion is composed of a first curved portion consisting only of a curve, a second curved portion consisting only of a curve, a third curved portion and a fourth curved portion that are connected to the first curved portion and the second curved portion and consist only of a curve having a larger curvature than the first curved portion and the second curved portion. By this configuration, the curvature of each curved portion can be adjusted according to the shape of the installation space during vehicle mounting. As a result, it is possible to install a liquid hydrogen tank with an increased liquid hydrogen loading amount without generating a large dead space.

[0025] Furthermore, by using a configuration that connects only curves, it is possible to reduce variations in stress distribution on the inner surface of the liquid hydrogen tank.

[0026] The first and second curved sections have a smaller curvature than the third and fourth curved sections, and therefore have lower rigidity compared to the regions of the third and fourth curved sections. Since a reinforcing section is formed in at least one of the regions of the first and second curved sections, it is possible to avoid stress concentration in the regions of the first and second curved sections when the internal pressure of the storage space increases. As a result, the pressure resistance strength is increased, and the durability of the liquid hydrogen tank can be improved.

[0027] Furthermore, since the pressure resistance can be increased by forming a reinforced section, the mass of the liquid hydrogen tank can be reduced compared to the case where the thickness of the material constituting the liquid hydrogen tank is partially increased to achieve the same pressure resistance. Furthermore, measures to increase the pressure resistance of liquid hydrogen tanks can be easily implemented.

[0028] Furthermore, since the reinforcing portion is formed to protrude inward, it prevents deformation and damage to the liquid hydrogen tank, provides insulation to enable stable storage of liquid hydrogen, and prevents the reinforcing portion from obstructing the outer tank which is installed outside the liquid hydrogen tank. [Brief explanation of the drawing]

[0029] [Figure 1] This is a perspective view of an on-board liquid hydrogen tank. [Figure 2] This is a cross-sectional view of the body of an on-board liquid hydrogen tank in the axial direction. [Figure 3] This is an embodiment of the present invention, shown as cross-sectional view AA in Figure 2. [Figure 4] (a) is an enlarged view of section B in Figure 2, and (b) is an enlarged view of section C in (a). [Modes for carrying out the invention]

[0030] Embodiments of the present invention will be described with reference to Figures 1 to 4. Figure 1 is a perspective view of an on-board liquid hydrogen tank, and Figure 2 is an axial cross-sectional view of the body of the on-board liquid hydrogen tank. This on-board liquid hydrogen tank 1 is mounted on a vehicle and stores hydrogen in a liquid state. The on-board liquid hydrogen tank 1 is mounted, for example, on a hydrogen engine vehicle or a fuel cell vehicle. The following description will focus on an on-board liquid hydrogen tank 1 mounted on a hydrogen engine vehicle.

[0031] As shown in Figure 2, the on-board liquid hydrogen tank 1 consists of two layers: a liquid hydrogen tank 10 located inside for storing hydrogen in a liquid state, and an outer tank 30 offset to the outside of the liquid hydrogen tank 10. A thermal insulation gap 40 of a predetermined thickness is formed between the liquid hydrogen tank 10 and the outer tank 30. The thermal insulation gap 40 comprises a thermal insulation region 41 partially filled with thermal insulation material and a vacuum region 42 not filled with thermal insulation material.

[0032] In the on-board liquid hydrogen tank 1, the pressure of the liquid hydrogen stored in the liquid hydrogen tank 10 is the same as atmospheric pressure, or slightly higher than atmospheric pressure, for example, 1 MPa or less. Furthermore, the liquid hydrogen tank 10 stores the liquid hydrogen at a temperature well below its boiling point (-252.9°C at atmospheric pressure).

[0033] As shown in Figure 1, the outer tank 30 comprises a pair of outer end plates 31 arranged opposite each other, and a cylindrical outer body 32 connecting the outer edges of the pair of outer end plates 31. The overall shape of the on-board liquid hydrogen tank 1 is a barrel shape that is slightly flattened vertically. The outer end plates 31 and the outer body 32 are connected by welding.

[0034] Furthermore, as shown in Figure 2, the liquid hydrogen tank 10, like the outer tank 30, comprises a pair of end plates 11 arranged facing each other, and a cylindrical body 12 connecting the outer edges of the pair of end plates 11. The end plates 11 and the body 12 are connected by welding. A collector section 20 is formed at the lower part of the body section 12. A pump 60 is installed in the collector section 20.

[0035] The liquid hydrogen tank 10 is made of a metal that does not exhibit low-temperature embrittlement, such as stainless steel, particularly 18-8 stainless steel. Similarly, the outer tank 30 is also made of a metal that does not exhibit low-temperature embrittlement, such as stainless steel, just like the liquid hydrogen tank 10.

[0036] The outer tank 30 of the on-board liquid hydrogen tank 1 is equipped with a liquid hydrogen filling port 33, a hydrogen gas return port 34, a pump port 35, and a boil-off port 36 on its side. Additionally, an outer collector portion 38 is formed on the outside of the collector portion 20 of the liquid hydrogen tank 10.

[0037] The liquid hydrogen filling port 33 is a port that accepts the supply of liquid hydrogen and is connected to the liquid hydrogen tank 10.

[0038] The hydrogen gas return port 34 is a port for drawing hydrogen gas (so-called boil-off gas) that has vaporized due to spontaneous heat input during the supply of liquid hydrogen back to the supply source. This hydrogen gas return port 34 is also connected to the liquid hydrogen tank 10.

[0039] Pump port 35 is the port through which the cylinder of pump 60 (Figure 2) is inserted, and is connected to the liquid hydrogen tank 10. Pump 60 is a booster pump that pressurizes and pumps up liquid hydrogen stored in the liquid hydrogen tank 10 in response to requests from the hydrogen engine. For example, the high-pressure liquid hydrogen pumped up after being pressurized to 5 MPa to several tens of MPa is vaporized and supplied to the engine as high-pressure hydrogen gas.

[0040] Furthermore, the boil-off port 36 is a port for releasing hydrogen gas, also known as boil-off gas, which is produced when liquid hydrogen vaporizes due to natural heat input, to the outside of the tank. This boil-off port 36 is also connected to the liquid hydrogen tank 10. A valve 37 is connected to the boil-off port 36, and when the internal pressure of the liquid hydrogen tank 10 exceeds a specified pressure, the valve 37 opens and releases the boil-off gas to the outside of the tank.

[0041] Figure 3 is a cross-sectional view of section AA in Figure 2, which is a cross-sectional view of the end plate section 11 of the liquid hydrogen tank 10 perpendicular to the axial direction of the body section 12. Figure 4(a) is an enlarged view of section B in Figure 2, which corresponds to axis Y in Figure 3. Figure 4(b) is an enlarged view of section C in Figure 4(a).

[0042] In Figure 4(b), a is the length of the flange portion 17, b is the distance from the continuity portion 19 between the flange portion 17 and the curved surface portion 18 to the reinforcing portion 50, c is the protruding length of the reinforcing portion 50, and d is the thickness of the reinforcing portion 50. Also, in Figure 4(a), e is the length of the inner surface of the liquid hydrogen tank 10 in the direction of axis Y (Figure 3), and f is the height of the end plate portion 11.

[0043] As shown in Figure 3, the outer edge of the end plate portion 11 is composed of a first curved portion 13 which is a less curved circular arc DE, a second curved portion 14 which is a less curved circular arc FG which is opposite the first curved portion 13, a third curved portion 15 which is a less curved circular arc DF which is connected to the first curved portion 13 and the second curved portion 14, and a fourth curved portion 16 which is a less curved circular arc EG which is connected to the first curved portion 13 and the second curved portion 14. The curvature of the first curved portion 13, the second curved portion 14, the third curved portion 15, and the fourth curved portion 16 is constant over the entire length of each curved portion.

[0044] The curvature of the third curved section 15 and the fourth curved section 16 is greater than that of the first curved section 13 and the second curved section 14. In this embodiment, the curvature of the first curved section 13 and the second curved section 14 are the same, and the curvature of the third curved section 15 and the fourth curved section 16 are the same. Therefore, the cross-section of the end plate portion 11 perpendicular to the axial direction of the body portion 12 is elongated horizontally in the direction of axis X, as shown in Figure 3, and is configured to be symmetrical with respect to axes X and Y. The cross-section of the body portion 12 is similar.

[0045] The end plate portion 11 consists of a flange portion 17 connected to the end of the body portion 12, and a curved surface portion 18 that is continuous with the flange portion 17 and whose axial cross-section of the body portion 12 consists only of a convex curve in the direction away from the flange portion 17. The end plate portion 11 is manufactured by press working. The flange portion 17 and the body portion 12 are connected by welding. As shown in Figure 4(a), the end plate portion 11 has an arc shape at the connection point between the flange portion 17 and the curved surface portion 18, and the curved surface portion 18 is a convex curve formed in an arc shape with the maximum protrusion at the halfway point of e, i.e., at the center. Furthermore, the end plate portion 11 of this embodiment is a shallow dish-shaped end plate with a gentle slope of the inner radius at the center and a reduced amount of protrusion from the flange portion 17. Note that the end plate portion 11 is not limited to a shallow dish-shaped end plate.

[0046] As shown in Figures 2, 3, 4(a), and 4(b), the end plate portion 11 has a reinforcing portion 50 that extends inward. The reinforcing portion 50 is made of the same 18-8 stainless steel as the liquid hydrogen tank 10 and is manufactured by bending a square bar to conform to the shape of the inner surface of the end plate portion 11.

[0047] As shown in Figure 3, the reinforcing section 50 is formed by extending over the entire area of ​​the first curved section 13 and the second curved section 14, and to a portion of the area of ​​the third curved section 15 and the fourth curved section 16. Furthermore, as shown in Figures 4(a) and 4(b), the reinforcing portion 50 is formed on the curved surface portion 18 side of the continuous portion 19 between the flange portion 17 and the curved surface portion 18 in the axial direction of the body portion 12.

[0048] Furthermore, the reinforcing portion 50 is perpendicular to the axial direction of the body portion 12 and is connected to the inner surface of the end plate portion 11 by welding at opposing positions in the vertical direction of the liquid hydrogen tank 10. Here, "perpendicular" and "opposite positions" are not strictly defined.

[0049] In this embodiment, e is 535 mm, f is 127 mm, and a is 20 mm. The plate thickness of the liquid hydrogen tank 10 is 3 mm.

[0050] In a liquid hydrogen tank 10, the stress in the regions of the first curved section 13 and the second curved section 14 was compared with and without the formation of the reinforced section 50. The stress values ​​were calculated by CAD analysis. As a result, a significant reduction in stress was confirmed by forming the reinforced section 50.

[0051] Furthermore, comparing the stress when the reinforcing portion 50 is formed in the end plate portion 11 at the continuous portion 19 between the flange portion 17 and the curved portion 18, and when it is formed on the curved portion 18 side of the continuous portion 19 between the flange portion 17 and the curved portion 18, it was found that the stress was lower when the reinforcing portion 50 was formed on the curved portion 18 side of the continuous portion 19 between the flange portion 17 and the curved portion 18.

[0052] Furthermore, regarding the formation position of the reinforcement portion 50, a comparison of cases where b is 10 mm and 20 mm revealed that the stress was lower with 10 mm. Similarly, regarding the thickness d of the reinforcement portion 50, a comparison of cases where it is 10 mm and 20 mm revealed that the stress was lower with 10 mm. Finally, regarding the protruding length c of the reinforcement portion 50, a comparison of cases where it is 30 mm and 19 mm revealed that the stress was lower with 30 mm.

[0053] Therefore, it was confirmed that the lowest stress was achieved when the reinforcing section 50 was formed with b=10mm, c=30mm, and d=10mm.

[0054] As shown in Figure 2, the reinforcing portion 50 is also formed on the body portion 12. The reinforcing portion 50 of the body portion 12 is formed around the entire circumference of the inner surface of the liquid hydrogen tank 10. Note that the reinforcing portion 50 of the body portion 12 may be formed in the same position and shape as the end plate portion 11. Also, the reinforcing portion 50 may not be formed on the body portion 12.

[0055] As detailed above, the above embodiment provides the following effects. (1) In the above embodiment, in the liquid hydrogen tank 10, in the cross section perpendicular to the axial direction of the body portion 12, the outer edge of the end plate portion 11 is composed of a first curved portion 13 consisting only of curves, a second curved portion 14 consisting only of curves, and a third curved portion 15 and a fourth curved portion 16 connected to the first curved portion 13 and the second curved portion 14 and consisting only of curves with a greater curvature than the first curved portion 13 and the second curved portion 14. As such, an on-board liquid hydrogen tank 1 with an increased liquid hydrogen storage capacity can be installed without generating a large dead space.

[0056] (2) Furthermore, by constructing it by connecting only curves, it is possible to reduce the variation in the pressure distribution on the inner surface of the liquid hydrogen tank 10.

[0057] (3) Furthermore, since the curved surface portion 18 of the end plate portion 11 is composed only of a curve that is convex in the direction away from the flange portion 17, even in the axial cross-section of the body portion 12, variations in the pressure distribution applied to the inner surface of the curved surface portion 18 can be reduced. Also, since the curved surface portion 18 is a shallow dish-shaped end plate with a gentle slope of the inner radius in the central part and a small amount of protrusion from the flange portion 17, the axial length of the body portion 12 can be set to be longer. Therefore, an on-board liquid hydrogen tank 1 with an increased liquid hydrogen carrying capacity can be installed.

[0058] (4) Furthermore, the end plate portion 11 is composed of a flange portion 17 connected to the end of the body portion 12 and a curved surface portion 18 that is continuous with the flange portion 17 and whose axial cross-section of the body portion 12 is a convex curve in the direction away from the flange portion 17. Therefore, welding the end plate portion 11 to the body portion 12 is easier compared to welding the body portion 12 to the curved surface portion 18. In addition, deformation of the end of the curved surface portion 18 can be prevented, so that the durability of the liquid hydrogen tank 10 does not decrease due to deformation.

[0059] (5) Furthermore, since reinforcing portions 50 are formed in the regions of the first curved section 13 and the second curved section 14, the pressure resistance can be increased in the regions where the reinforcing portions 50 are formed. Therefore, when the internal pressure of the storage space rises, it is possible to avoid stress concentration in the regions of the first curved section 13 and the second curved section 14. As a result, the pressure resistance is increased, and the durability of the liquid hydrogen tank 10 can be improved.

[0060] (6) Furthermore, since the reinforcing portion 50 is formed on the curved surface portion 18 side of the continuous portion 19 between the flange portion 17 and the curved surface portion 18, stress concentration at the curved surface portion 18 can be avoided in the cross section perpendicular to the axial direction of the body portion 12, compared to the case where the reinforcing portion 50 is formed at the continuous portion 19 between the flange portion 17 and the curved surface portion 18. As a result, the pressure resistance strength is increased, and the durability of the liquid hydrogen tank 10 can be improved.

[0061] (7) Furthermore, since the reinforcing portion 50 extends to a part of the region of the third curved portion 15 and the fourth curved portion 16, the durability of the liquid hydrogen tank 10 can be further improved by forming the end of the reinforcing portion 50 where stress concentration occurs within the more robust third curved portion 15 and the fourth curved portion 16.

[0062] (8) Furthermore, since the pressure resistance can be increased by forming the reinforcing portion 50, the mass of the liquid hydrogen tank can be reduced compared to the case in which the thickness of the material constituting the liquid hydrogen tank 10 is partially increased to achieve the same pressure resistance of the liquid hydrogen tank 10. Furthermore, measures to increase the pressure resistance of the liquid hydrogen tank 10 can be easily implemented.

[0063] (9) Since the reinforcing portion 50 is formed to protrude inward from the body portion 12, the pressure resistance strength of the body portion 12 can be increased. Furthermore, since the reinforcing portion 50 is formed to protrude inward, it prevents deformation and damage to the liquid hydrogen tank 10, provides an insulating function to enable stable storage of liquid hydrogen, and prevents the reinforcing portion 50 from becoming an obstruction to the outer tank 30 which is disposed outside the liquid hydrogen tank 10.

[0064] In addition to what is stated in the claims, the present invention includes the following aspects. The liquid hydrogen tank according to claim 3, wherein the reinforcing portion is also formed to protrude inward from the body portion, as described in claim 4.

[0065] In carrying out the present invention, the invention is not limited to the embodiments described above, and various modifications are possible as long as they do not depart from the purpose of the invention.

[0066] For example, in the above embodiment, the first curved section 13, the second curved section 14, the third curved section 15, and the fourth curved section 16 are all formed in an arc shape, but all of them may be composed of curves that are not arc-shaped. Alternatively, at least one may be composed in an arc shape.

[0067] For example, in the above embodiment, the reinforcing portion 50 is formed on both sides of the first curved portion 13 and the second curved portion 14, but it may also be formed on one side. Considering the pressure increase inside the liquid hydrogen tank 10 due to hydrogen gas generated when liquid hydrogen vaporizes due to natural heat input and the effect of the reinforcing portion 50, if it is formed on one side, it is desirable to form it on the side of the first curved portion 13 where the pressure increase due to vaporized hydrogen acts.

[0068] For example, in the above embodiment, the reinforcing portion 50 was formed by extending it to a part of the region of the third curved portion 15 and the fourth curved portion 16, but it may also be formed only in the region of the first curved portion 13 and the second curved portion 14 without extending it to the third curved portion 15 and the fourth curved portion 16. Alternatively, in the region of the first curved portion 13 and the second curved portion 14, the protruding length of the reinforcing portion 50 may be changed in a direction that shortens it toward the third curved portion 15 and the fourth curved portion 16.

[0069] The present invention can also be applied to a liquid hydrogen tank 10 in which the curvature of the curve changes continuously, such as when the outer edge of the end plate portion 11 is elliptical. In this case, the curves located vertically between two foci on the major axis of the ellipse can be designated as the first curve portion 13 and the second curve portion 14, and the curves located outside the two foci can be designated as the third curve portion 15 and the fourth curve portion 16 to form the reinforcing portion 50. [Explanation of Symbols]

[0070] 1. Onboard liquid hydrogen tank 10 Liquid hydrogen tanks 11. End plate section 12 Torso 13 1st curve section 14 Second curve section 15 Third curve section 16 4th curve section 17 Flange section 18 Curved part 19 Continuous section 30 Outer tank 40 Thermal gap 50 Reinforcement section

Claims

1. A pair of end plates arranged to face each other, A liquid hydrogen tank comprising a body portion connecting the outer edges of the pair of end plates, and capable of storing liquid hydrogen inside, The outer edge of the end plate portion is composed of a first curved section consisting solely of curves, a second curved section consisting solely of curves, and third and fourth curved sections connected to the first and second curved sections, each consisting solely of curves with a greater curvature than the first and second curved sections. A liquid hydrogen tank characterized in that a reinforcing portion is formed in at least one of the first curved portion and the second curved portion of the end plate, projecting inward.

2. The end plate portion comprises a flange portion connected to the end of the body portion, The flange portion is continuous with the body portion, and the axial cross-section of the body portion is composed of a curved surface portion which is convex in the direction away from the flange portion, The liquid hydrogen tank according to claim 1, wherein the reinforcing portion is formed on the curved surface side of the continuous portion between the flange portion and the curved surface portion.

3. The liquid hydrogen tank according to claim 1 or claim 2, wherein the reinforcing portion extends to a portion of at least one of the regions of the third curved portion and the fourth curved portion.

4. The liquid hydrogen tank according to claim 1 or claim 2, wherein the reinforcing portion is also formed to protrude inward from the body portion.

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