On-board liquid hydrogen tank and manufacturing method thereof

Abstract

To provide an on-vehicle liquid hydrogen tank which can store liquid hydrogen more stably, and to provide a method for manufacturing the on-vehicle liquid hydrogen tank.SOLUTION: An on-vehicle liquid hydrogen tank 10 includes: an inner tank 12 that stores liquid hydrogen; an outer tank 14 that accommodates the inner tank 12; and a heat-insulation material 16 that is arranged in a heat-insulation clearance 18 formed as a clearance between the inner tank 12 and the outer tank 14 and holds the inner tank 12 in a state where the inner tank 12 is separated from an inner surface of the outer tank 14. The heat-insulation clearance 18 has: a vacuum area 17 that is not filled with the heat-insulation material 16; and an area that is filled with the heat-insulation material 16 and thus allows the inner tank 12 to be supported on its surface by the heat-insulation material 16.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This specification discloses an on-board liquid hydrogen tank for storing liquid hydrogen and a method for manufacturing the same. [Background technology]

[0002] On-board liquid hydrogen tanks that store hydrogen in a liquid state have been known for some time. For example, Patent Document 1 discloses a technology in which a metal inner tank is placed inside an outer tank made of a reinforced fiber material and liquid hydrogen is stored in this inner tank. In Patent Document 1, a vacuum insulation layer is formed between the outer tank and the inner tank. In addition, buffer material is partially placed between the outer tank and the inner tank, and the inner tank is suspended and supported by the buffer material inside the outer tank. With such an on-board liquid hydrogen tank, the vacuum insulation layer inhibits heat transfer to the inner tank, making it possible to maintain a low temperature inside the inner tank and suppress evaporation of liquid hydrogen. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-066426 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the configuration of Patent Document 1, the inner tank is suspended and supported by buffer materials that are partially arranged. In this case, if a strong impact is applied to the on-board liquid hydrogen tank, the buffer materials may be damaged or deformed, causing the inner tank to collide with the outer tank and resulting in deterioration or damage to the inner tank. If the inner tank is damaged or deteriorated, various problems may occur, such as hydrogen leakage.

[0005] Therefore, this specification discloses an on-board liquid hydrogen tank that can store liquid hydrogen more stably, and a method for manufacturing the same. [Means for solving the problem]

[0006] The on-board liquid hydrogen tank disclosed in this specification comprises an inner tank for storing liquid hydrogen, an outer tank for accommodating the inner tank, and a thermal insulating material disposed in the insulating gap between the inner tank and the outer tank, for keeping the inner tank separated from the inner surface of the outer tank, and is characterized in that the insulating gap has a vacuum region not filled with the thermal insulating material, and a region filled with the thermal insulating material so that the inner tank is surface-supported by the thermal insulating material.

[0007] In the vacuum region, heat is not transferred by any means other than radiation. Therefore, by providing a vacuum region, the thermal insulation of the inner tank can be maintained at a high level. On the other hand, if there is only a vacuum region, there is a risk that the inner tank will collide with the outer tank in the event of a vehicle collision. However, as described above, by filling the insulating gap with insulating material and providing an area in which the inner tank is surface-supported by the insulating material, it is possible to prevent the inner tank from colliding with the outer tank. In other words, with the above configuration, it is possible to prevent the inner tank from colliding with the outer tank in the event of a vehicle collision while maintaining high thermal insulation. This effectively prevents deformation and damage to the inner tank, allowing for more stable storage of liquid hydrogen.

[0008] In this case, the insulation material includes super insulation formed by laminating one or more heat shield layers made of metal sheets and one or more spacer layers made of fiber material, and the insulation gap may be vacuum suctioned with the insulation material in place.

[0009] By using super insulation, the temperature rise of liquid hydrogen can be prevented more effectively.

[0010] The heat insulating material may be contained in a sealed bag, and both the inside of the sealed bag and the heat insulating gap may be subjected to vacuum suction.

[0011] This configuration simplifies the manufacture of the liquid hydrogen tank.

[0012] The outer tank may also have a rupture disk that breaks when the internal pressure of the outer tank exceeds a specified allowable pressure, thereby opening the inside of the outer tank to the atmosphere.

[0013] This configuration can prevent the internal pressure of the outer tank from becoming excessively high, improving the safety of the liquid hydrogen tank.

[0014] The inner tank may have a shape having a flat surface.

[0015] By placing a heat insulating material in the gap between the outer and inner tanks, the internal pressure of the inner tank is dispersed to the outer tank and the heat insulating material, improving the maximum allowable pressure of the inner tank. Furthermore, even if the inner tank deforms, the inner tank does not come into direct contact with the outer tank, so the heat insulating properties are maintained. This makes it possible to form the inner tank into a shape with flat surfaces.

[0016] Furthermore, the tank may further include a booster pump that pressurizes the liquid hydrogen stored in the inner tank and outputs it to the outside, and the bottom of the inner tank may be formed with a collector section that is recessed downward and into which the lower end of the booster pump is inserted.

[0017] This configuration allows the pressure of the stored liquid hydrogen to be kept low, and also the maximum allowable pressure required for the inner tank to be kept low, thereby reducing the cost and weight of the hydrogen tank.

[0018] The method for manufacturing an on-board hydrogen tank disclosed in this specification is characterized in that an insulating material containing a fibrous material is placed in a sealed bag, the inside of the sealed bag is vacuumed, an inner tank for storing liquid hydrogen is placed inside an outer tank, and the sealed bag is placed in the insulating gap between the tank and the outer tank, and then the insulating gap is vacuumed.

[0019] By vacuum-suctioning the sealed bag in advance, the insulating material is compressed. This makes it easy to place the insulating material in the gap between the outer tank and the inner tank. Furthermore, by vacuum-suctioning the insulating gap after placing the insulating material, the pressure difference between the inside and outside of the sealed bag decreases, causing the insulating material to expand and fill the gap. In other words, with the above configuration, it is easy to manufacture a liquid hydrogen tank that can store liquid hydrogen more stably. [Effects of the Invention]

[0020] According to the technology disclosed in this specification, liquid hydrogen can be stored more stably. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a perspective view of an on-board liquid hydrogen tank. [Figure 2] FIG. 2 is a cross-sectional view of an on-board liquid hydrogen tank. [Figure 3] FIG. 1 is a schematic diagram showing a state of an on-vehicle liquid hydrogen tank during a collision. [Figure 4] FIG. 2 is a schematic diagram showing the manufacturing process of an on-board liquid hydrogen tank. [Figure 5A] FIG. 2 is a schematic diagram showing the state of the insulating material before vacuum suction is applied to the insulating gap. [Figure 5B] FIG. 10 is a schematic diagram showing the state of the insulating material after the insulating gap has been vacuum suctioned. [Figure 6] 1 is a flowchart showing a manufacturing process of an on-board liquid hydrogen tank. [Figure 7] FIG. 10 is a schematic diagram showing another example of an on-board liquid hydrogen tank. [Figure 8] FIG. 2 is a schematic diagram showing an on-board liquid hydrogen tank of a comparative example. [Figure 9] FIG. 10 is a schematic diagram showing a state of an on-vehicle liquid hydrogen tank of a comparative example during a collision. DETAILED DESCRIPTION OF THE INVENTION

[0022] The structure of a liquid hydrogen tank 10 (hereinafter referred to as "hydrogen tank 10") will be described below with reference to the drawings. FIG. 1 is a perspective view of hydrogen tank 10. FIG. 2 is a cross-sectional view of hydrogen tank 10. This hydrogen tank 10 is mounted on a vehicle and stores hydrogen in a liquid state. There are no particular limitations on the type of vehicle that can mount such a hydrogen tank 10, but for example, the hydrogen tank 10 can be mounted on a fuel cell vehicle or a hydrogen engine vehicle. The following explanation will be given taking as an example a hydrogen tank 10 mounted on a hydrogen engine vehicle equipped with a direct injection hydrogen engine that injects high-pressure hydrogen gas into the engine cylinder.

[0023] The hydrogen tank 10 stores hydrogen in a liquid state. The pressure of the stored liquid hydrogen is the same as or slightly higher than atmospheric pressure, for example, 1 MPa or less. The hydrogen tank 10 also stores the liquid hydrogen at a temperature that is kept sufficiently lower than its boiling point (-252.9°C at atmospheric pressure).

[0024] As shown in Figure 1, the hydrogen tank 10 is shaped like a bale and has a cylindrical body 10a and a head plate 10b that closes both axial ends of the body 10a. The head plate 10b is dome-shaped and made up of curved surfaces. A locally depressed collector section 20 is provided at the bottom of the hydrogen tank 10. The collector section 20 is made up of a cylinder and a dome-shaped section that closes the end of the cylinder. As is clear from the explanation so far, almost all of the constituent surfaces of the hydrogen tank 10 are made up of curved surfaces. This configuration makes it possible to make the pressure distribution on the hydrogen tank 10 more uniform.

[0025] A liquid hydrogen fill port 26 and a hydrogen gas return port 28 are attached to the side of the hydrogen tank 10. The liquid hydrogen fill port 26 is a port that receives a supply of liquid hydrogen and is connected to the inner tank 12, which will be described later. The hydrogen gas return port 28 is a port that draws hydrogen gas that has evaporated due to natural heat input when liquid hydrogen is supplied (so-called boil-off gas) into the supply source side. This hydrogen gas return port 28 is also connected to the inner tank 12.

[0026] Furthermore, multiple ports, including a pump port 24 and a boil-off port 25, are provided at the top of the hydrogen tank 10. Note that FIG. 1 illustrates only the pump port 24 and the boil-off port 25, and the other ports are omitted. The pump port 24 is a port through which the cylinder of a pump 22 (see FIG. 2) is inserted and is a port that communicates with the inner tank 12. The pump 22 is a boost pump that pressurizes and pumps up the liquid hydrogen stored in the hydrogen tank 10 in response to demand from the hydrogen engine. The pressure of the liquid hydrogen after boosting is, for example, 5 MPa to several tens of MPa. The high-pressure liquid hydrogen pumped up by the pump 22 is vaporized and then directly injected into the engine cylinder as high-pressure hydrogen gas. In other words, in this example, only the amount of hydrogen required by the hydrogen engine is pressurized and extracted. This configuration allows the pressure of the liquid hydrogen stored in the hydrogen tank 10 to be kept low. As a result, the maximum allowable pressure of the hydrogen tank 10 can be kept low, thereby reducing the cost and weight of the hydrogen tank 10.

[0027] The suction port of pump 22 that draws in liquid hydrogen from the tank is located in collector section 20. With this configuration, liquid hydrogen can be pumped up by pump 22 even when the remaining amount of liquid hydrogen in the tank is low.

[0028] The boil-off port 25 is a port for discharging the hydrogen gas generated when liquid hydrogen is vaporized by natural heat input, known as boil-off gas, to the outside of the tank. This boil-off port 25 is in communication with the inner tank 12. A boil-off valve 29 (see Figure 2) is also connected to the boil-off port 25. The boil-off valve 29 opens when the internal pressure of the hydrogen tank 10 (more precisely, the inner tank 12) reaches or exceeds a specified release pressure, thereby discharging the boil-off gas to the outside of the tank.

[0029] As shown in Figure 2, this hydrogen tank 10 has an inner tank 12 that stores liquid hydrogen and an outer tank 14 that houses the inner tank 12. The inner tank 12 is made of a metal that does not become brittle at low temperatures, such as stainless steel, and in particular 18-8 stainless steel. As mentioned above, this inner tank 12 is shaped like a bale and has a collector section 20 at its bottom. The inner tank 12 is designed so that its maximum allowable pressure is approximately two to five times the release pressure mentioned above.

[0030] The outer tank 14 has a shape that is offset outward from the inner tank 12. Like the inner tank 12, the outer tank 14 is also made of a metal that is not brittle at low temperatures, such as stainless steel. An insulating gap 18, which is a gap of a predetermined thickness, is provided between the outer tank 14 and the inner tank 12. The thickness of this insulating gap 18 is almost constant and does not vary much from place to place.

[0031] The insulating gap 18 is partially filled with a heat insulating material 16, and the insulating gap 18 is evacuated. Therefore, the insulating gap has a vacuum region 17 that is not filled with the heat insulating material 16, and a region that is filled with the heat insulating material 16 and where the inner tank 12 is surface-supported by the heat insulating material 16. The heat insulating material 16 is a member that inhibits heat transfer from the outside to the inner tank 12 and keeps the inner tank 12 separated from the outer tank 14. In this specification, "filled" means a state in which the heat insulating material 16 is arranged in the insulating gap 18 so that the heat insulating material 16 contacts both the inner tank 12 and the outer tank 14.

[0032] The configuration of the heat insulating material 16 is not particularly limited as long as it has sufficient heat insulating performance. In this example, super insulation 34 is used as the heat insulating material 16. The super insulation 34 is configured by laminating one or more heat shield layers 30 and one or more spacer layers 32. The heat shield layer 30 is a layer that prevents heat radiation and is made of, for example, a sheet metal (such as aluminum). The spacer layer 32 is a layer that prevents heat transfer and is made of a fiber material, such as glass wool. Such super insulation 34 has an average thermal conductivity of 1×10-6 cal / sec.cm℃ or less.

[0033] The insulating material 16 and the insulating gap 18 (and thus the vacuum region 17) are both vacuumed. Vacuuming effectively prevents heat transfer to the inner tank 12, allowing the liquid hydrogen to be stored at a low temperature. The outer tank 14 is provided with a seal-off valve 36 that is connected to a suction pump (not shown) during vacuuming and that closes after vacuuming.

[0034] Furthermore, a rupture disk 38 is attached to the outer tank 14. The rupture disk 38 breaks when the internal pressure of the outer tank 14 exceeds a specified allowable pressure, thereby connecting the insulating gap 18 to the external space. By providing such a rupture disk 38, it is possible to prevent the internal pressure of the outer tank 14 from becoming excessively high, and the safety of the hydrogen tank 10 can be more reliably ensured.

[0035] As is clear from the above explanation, in this example, the insulating gap 18 between the inner tank 12 and the outer tank 14 is partially filled with insulating material 16. The reason for this configuration will be explained by comparing it with a comparative example. Figures 8 and 9 are schematic diagrams of a hydrogen tank 10* of the comparative example.

[0036] As shown in FIG. 8, the hydrogen tank 10* of the comparative example has the inner tank 12 suspended inside the outer tank 14 by a connecting member 40. The connecting member 40 connects the inner tank 12 and the outer tank 14 and is made of, for example, resin. The insulating gap 18 between the inner tank 12 and the outer tank 14 is vacuum-suctioned, providing high thermal insulation, although no insulating material 16 is provided. This hydrogen tank 10* is mounted on a vehicle. In this case, if the vehicle collides with an obstacle and a strong impact is applied to the hydrogen tank 10*, the connecting member 40 may be damaged, as shown in FIG. 9. In this case, gravity and inertial forces could cause the inner tank 12 to collide hard with the outer tank 14, potentially damaging the inner tank 12. If the inner tank 12 is damaged, the stored hydrogen will naturally leak, causing various problems.

[0037] On the other hand, in this example, a heat insulating material 16 is partially disposed around the inner tank 12, and the heat insulating material 16 is in contact with part of the outer surface of the inner tank 12. The thickness of this heat insulating material 16 is greater than the thickness of the insulating gap 18 in an unloaded state (i.e., a state in which the pressure difference between the inside and outside of the heat insulating material 16 is almost zero). Therefore, the heat insulating material 16 is in close contact with both the inner tank 12 and the outer tank 14, and keeps the inner tank 12 separated from the outer tank 14.

[0038] With this configuration, even if the vehicle collides with an obstacle, the inner tank 12 remains separated from the outer tank 14, thereby reducing the impact on the inner tank 12. FIG. 3 is a schematic diagram showing the state of the hydrogen tank 10 during a collision. As shown in FIG. 3, according to this example, the inner tank 12 may move slightly inside the outer tank 14 due to the impact of the collision. However, because the insulating material 16 is interposed between the inner tank 12 and the outer tank 14, the inner tank 12 continues to maintain a state of separation from the outer tank 14. This effectively prevents a collision between the inner tank 12 and the outer tank 14. As a result, damage to the inner tank 12 and, ultimately, hydrogen leakage can be more reliably prevented. In other words, according to this example, hydrogen can be stored more stably. Furthermore, in this example, a vacuum region 17, which is not filled with the insulating material 16, is provided in the insulating gap 18. In the vacuum region 17, heat is not transferred by any means other than radiation. By partially providing such a vacuum region 17, the heat insulating properties of the inner tank 12 can be maintained at a higher level.

[0039] As shown in Fig. 4, the outer tank 14 is formed by welding together multiple outer tank pieces 50a, 50b. For example, the outer tank 14 is formed by welding together a cylindrical body piece 50a and an end plate piece 50b that closes the end of the body piece 50a. When manufacturing the hydrogen tank 10, the outer tank pieces 50 are arranged around the inner tank 12, and a heat insulating material 16 is placed between the outer tank pieces 50 and the inner tank 12, and the outer tank pieces 50 are welded together. Once the outer tank 14 has been formed by welding, the insulating gap 18 is vacuum suctioned.

[0040] As described above, the thickness of the insulating material 16 is greater than the thickness of the insulating gap 18 in an unloaded state. Therefore, if the insulating material 16 is disposed between the inner tank 12 and the outer tank section 50 during the manufacturing process of the hydrogen tank 10, the inner tank 12 or the outer tank section 50 may be pressed and deformed by the insulating material 16, as shown in Figure 4, resulting in an inappropriate shape of the final inner tank 12 or outer tank 14. Furthermore, it was difficult to properly weld the outer tank section 50 when it was deformed.

[0041] Therefore, in this example, when manufacturing the hydrogen tank 10, the heat insulating material 16 is placed in a sealed bag 44 in advance, and this sealed bag 44 is vacuum-suctioned. This will be explained with reference to Figures 5A and 5B. Figures 5A and 5B are schematic diagrams showing the manufacturing process of the hydrogen tank 10.

[0042] As shown in FIG. 5A and as described above, the insulating material 16 is contained in a sealing bag 44. This sealing bag 44 has been vacuum-suctioned in advance. When manufacturing the hydrogen tank 10, this sealing bag 44 is placed in the insulating gap 18 between the inner tank 12 and the outer tank section 50. Before the outer tank section 50 is welded, the insulating gap 18 has not been vacuum-suctioned. Therefore, at this point, the insulating material 16 is pressed and compressed by atmospheric pressure. As a result, before the outer tank section 50 is welded, the insulating material 16 is sufficiently thinner than the insulating gap 18, as shown in FIG. 5A. Therefore, even if the insulating material 16 is placed in the insulating gap 18, the inner tank 12 or the outer tank section 50 will not be deformed by the pressing force from the insulating material 16. At this time, the sealing bag 44 may be temporarily adhered to the inner tank 12 or the outer tank section 50 to prevent the sealing bag 44 from moving within the insulating gap 18.

[0043] Once the insulating material 16 is properly positioned, workers weld the outer tank pieces 50 together to form the outer tank 14. After the outer tank 14 is formed, workers apply vacuum to the insulating gap 18. This reduces the pressure difference between the inside and outside of the sealing bag 44, and the compression of the insulating material 16 is released. Then, as shown in FIG. 5B, the insulating material 16 expands sufficiently and adheres tightly to both the inner tank 12 and the outer tank 14. Once this state is reached, the insulating material 16 keeps the inner tank 12 separated from the outer tank 14.

[0044] In this case, it is difficult to maintain a constant thickness of the insulating gap 18 at a stage before welding the outer tank section 50. Therefore, in this case, a spacer 54 (see FIGS. 5A and 5B) may be partially disposed between the inner tank 12 and the outer tank section 50. The configuration of the spacer 54 is not particularly limited as long as it can maintain a constant thickness of the insulating gap 18. Therefore, the spacer 54 may be made of resin or metal. Furthermore, the spacer 54 may or may not be bonded to at least one of the inner tank 12 and the outer tank 14. Furthermore, to prevent a concentrated load from being transmitted to a portion of the inner tank 12 via the spacer 54 during a vehicle collision, the spacer 54 may be configured to deform or break relatively easily. For example, the spacer 54 may have a bent portion or a weak portion to induce buckling.

[0045] Figure 6 is a flowchart showing the flow of manufacturing the hydrogen tank 10. As shown in Figure 6 and as described above, when manufacturing the hydrogen tank 10, an operator vacuums the sealed bag 44 containing the insulating material 16 (S10). Next, the outer tank piece 50 and the insulating material 16 are arranged around the inner tank 12 (S12). At this time, a spacer 54 may be arranged between the inner tank 12 and the outer tank piece 50 to maintain the thickness of the insulating gap 18 as designed.

[0046] Next, the worker welds the outer tank pieces 50 together to form a sealed outer tank 14 (S14). After that, the worker connects the seal-off valve 36 to a suction pump (not shown) and applies vacuum to the insulating gap 18 (S16). This reduces the pressure difference between the inside and outside of the sealing bag 44, causing the insulating material 16 to expand. The expanded insulating material 16 comes into contact with both the outer tank 14 and the inner tank 12, and holds the inner tank 12 apart from the outer tank 14.

[0047] As is clear from the above explanation, this example is provided with a heat insulating material 16 that keeps the inner tank 12 separated from the outer tank 14. With this configuration, even if the vehicle collides with an obstacle and a strong impact is applied to the hydrogen tank 10, damage to the inner tank 12 can be effectively prevented.

[0048] Furthermore, in this example, the internal pressure acting on the inner tank 12 can be dispersed and transmitted to the heat insulating material 16 and the outer tank 14. Therefore, according to this example, the maximum allowable pressure of the hydrogen tank 10 can be increased without increasing the wall thickness of the inner tank 12 and the outer tank 14.

[0049] Furthermore, providing the insulating material 16 improves the flexibility of the shape of the inner tank 12. Specifically, the inner tank 12 can be shaped to have flat surfaces. For example, as shown in FIG. 7, the inner tank 12 may be shaped to have a substantially cubic shape with multiple flat surfaces 60. That is, if the insulating material 16 is not disposed in the insulating gap 18 and the flat surfaces 60 are provided on the inner tank 12, a large pressure will act on the flat surfaces. In this case, there is a risk that the inner tank 12 will deform at the flat surfaces 60 and come into contact with the outer tank 14. If a part of the inner tank 12 comes into contact with the outer tank 14, the insulating performance will rapidly deteriorate, making it difficult to maintain the liquid hydrogen at a low temperature. For this reason, conventional inner tanks 12 do not have flat surfaces 60 and are composed only of curved surfaces. That is, conventional inner tanks 12 are usually shaped like a rice bag or a sphere.

[0050] On the other hand, when the insulation material 16 is partially provided in the insulation gap 18 as in this example, even if a flat surface 60 is provided on the inner tank 12, the pressure acting on the flat surface 60 can be received by the insulation material 16 and the outer tank 14. As a result, deformation of the inner tank 12 can be effectively prevented. Furthermore, even if the inner tank 12 does deform, the inner tank 12 can be effectively prevented from coming into contact with the outer tank 14, and high insulation performance can be maintained. Therefore, according to this example, the degree of freedom in the shape of the inner tank 12 can be improved.

[0051] Note that the configurations described so far are all examples, and other configurations may be changed as long as the insulating material 16 is at least partially filled between the inner tank 12 and the outer tank 14. For example, in the above description, the insulating material 16 is contained in a sealed bag 44, but the insulating material 16 may be placed directly in the insulating gap 18 without being contained in the sealed bag 44. The shape of the hydrogen tank 10 may also be changed as appropriate, and may be, for example, spherical, rugby ball-shaped, rectangular, or the like. Furthermore, in this example, the hydrogen tank 10 is provided with a booster pump 22, but this is not necessary. [Explanation of symbols]

[0052] 10,10* Hydrogen tank, 12 Inner tank, 14 Outer tank, 16 Insulation material, 18 Insulation gap, 20 Collector section, 22 Pump, 24 Pump port, 25 Boil-off port, 26 Liquid hydrogen filling port, 28 Hydrogen gas return port, 29 Boil-off valve, 30 Heat shield layer, 32 Spacer layer, 34 Super insulation, 36 Seal-off valve, 38 Rupture disk, 40 Connecting member, 44 Sealing bag, 50 Outer tank piece, 54 Spacer, 60 Flat section.

Claims

1. an inner tank for storing liquid hydrogen; an outer tank that accommodates the inner tank; a heat insulating material disposed in a heat insulating gap between the inner tank and the outer tank, the heat insulating material maintaining the inner tank spaced apart from the inner surface of the outer tank; the insulation gap has a vacuum region that is not filled with the insulation material and a region that is filled with the insulation material and thereby the inner tank is surface-supported by the insulation material, The heat insulating material includes a super insulation formed by laminating one or more heat shield layers made of a metal sheet and one or more spacer layers made of a fiber material, The insulating gap is vacuum suctioned with the insulating material disposed therein, The insulating material is contained in a sealed bag, Both the inside of the sealed bag and the insulating gap are vacuum suctioned. An on-board liquid hydrogen tank.

2. 2. The on-board liquid hydrogen tank according to claim 1, The outer tank has a rupture disk that is broken when the internal pressure of the outer tank exceeds a specified allowable pressure, thereby opening the inside of the outer tank to the atmosphere. An on-board liquid hydrogen tank.

3. 2. The on-board liquid hydrogen tank according to claim 1, 1. An on-vehicle liquid hydrogen tank, wherein the inner tank has a shape having a flat surface.

4. 2. The on-board liquid hydrogen tank according to claim 1, further comprising: a booster pump that pressurizes the liquid hydrogen stored in the inner tank and outputs it to the outside, a collector portion that is recessed downward at the bottom of the inner tank and into which the lower end of the booster pump is inserted; An on-board liquid hydrogen tank.

5. A method for manufacturing an on-board liquid hydrogen tank, comprising: The insulating material containing the fiber material is placed in a sealed bag, and then the inside of the sealed bag is vacuum-suctioned. an inner tank for storing liquid hydrogen is placed inside the outer tank, and the sealing bag is placed in an insulating gap between the inner tank and the outer tank, and then the insulating gap is vacuum suctioned. A method for manufacturing an on-vehicle liquid hydrogen tank.

6. 2. The on-board liquid hydrogen tank according to claim 1, further comprising:

1. An on-vehicle liquid hydrogen tank comprising: a spacer disposed partially in the insulating gap to maintain a constant thickness of the insulating gap.

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