Gas container

Abstract

To fix and hold a storage member while sufficiently securing the amount of gas stored in an internal space of a container body.SOLUTION: A gas container comprises: a cylindrical container body comprising an internal space for storing gas; a mouthpiece attached to an axial end part of the container body, and comprising a communication passage for causing the internal space to communicate with the outside of the container body; and a storage member arranged in the internal space, and for occluding and releasing the gas. The storage member comprises one of a concave part and a convex part provided in a radially outer surface, and engaged with each other. The container body comprises the other of the convex part and the concave part provided in a radially inner surface.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a gas container capable of storing and releasing gas.

Background Art

[0002] Gas containers (for example, Patent Document 1) that are mounted on vehicles and the like and store and release gases such as hydrogen gas and natural gas are known. The gas container described in Patent Document 1 includes a storage member such as a hydrogen storage alloy. The storage member is housed in the internal space of the container body. The storage member physically or chemically stores and releases the gas to be stored. According to this storage member, the amount of gas that can be stored in the internal space of the container body can be increased.

[0003] By the way, as a structure for housing the storage member in the internal space of the gas container, as described in Patent Document 1, an accommodating member disposed in the internal space may be used. This accommodating member is formed, for example, in a cylindrical shape extending in the axial direction, and has a shape in which a plurality of regularly arranged accommodating spaces partitioned by partition walls are formed. And the accommodating member is fixed to the axial end portion of the container body or the like via a connecting portion or the like at the axial end portion. And the storage member extends in the axial direction following the shape of each storage space of the storage member, and is stored in each storage space. According to this structure, the storage member can be stored and held in each storage space of the accommodating member disposed in the internal space of the container body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the gas container described in Patent Document 1, in order to accommodate the storage member in the internal space of the container body, it is necessary to accommodate an accommodation member for holding the storage member in the internal space. For this reason, the structure inside the gas container becomes complicated, and the volume of the storage member decreases by the volume of the accommodation member in the internal space, so the amount of gas that can be stored in the internal space decreases.

[0006] On the other hand, if the storage member is directly accommodated in the internal space of the container body, the volume of the storage member becomes large, so the amount of gas that can be stored in the internal space can be increased. However, in this structure, if the storage member can freely move relative to the container body in the axial direction or the rotational direction around the axis in the internal space, for example, in the case of a storage member formed by solidifying powder, there is a risk that damage will occur due to rubbing between the storage member and the inner surface of the container body, etc., and powdering will be promoted.

[0007] The present invention has been made in view of such points, and an object thereof is to provide a gas container capable of realizing fixed holding of a storage member while sufficiently securing the amount of gas stored in the internal space of the container body.

Means for Solving the Problems

[0008] One aspect of the present invention includes a cylindrical container body having an internal space for storing gas, a base attached to an axial end of the container body and having a communication passage for communicating the internal space to the outside of the container body, and a storage member disposed in the internal space for occluding and releasing gas. The storage member has either a concave portion or a convex portion provided on the radially outer surface that engages with each other, and the container body has the other of the concave portion and the convex portion provided on the radially inner surface, and is a gas container.

[0009] According to this configuration, it is possible to realize fixed holding of the storage member while sufficiently securing the amount of gas stored in the internal space of the container body.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0011] Hereinafter, specific embodiments of the gas container according to the present invention will be described with reference to FIGS. 1 to 5.

[0012] A gas container 1 according to an embodiment is a container that stores gas and discharges the stored gas. The gas container 1 is mounted on a vehicle or the like that uses the stored gas as fuel. The gas stored in the gas container 1 may be any type of gas, but is preferably a fuel gas such as hydrogen gas or natural gas. Also, the pressure of the gas that the gas container 1 can store may be any, but may be a high pressure (for example, 100 MPa or the like). That is, the gas container 1 may be a pressure vessel or a pressure-resistant container.

[0013] As shown in FIG. 1, the gas container 1 includes a container body 10, caps 20 and 30, a reinforcing member 40, and a storage member 60.

[0014] The container body 10 is a liner for storing gas. The container body 10 has an internal space 11. The internal space 11 has a capacity capable of storing a predetermined amount of gas. The container body 10 is made of a material having a gas barrier property that does not permeate or hardly permeates the gas stored in the internal space 11. Note that the material of the container body 10 may be selected according to the use environment of the gas container 1 and the like.

[0015] For example, when the gas is hydrogen, the material of the container body 10 is polyethylene resin, polypropylene resin, or the like. Incidentally, the interior of the container body 10 may be coated with a material having excellent gas barrier properties, such as ethylene-vinyl alcohol copolymer (EVOH). Also, when the gas container 1 is used for household purposes and the mass of the gas container 1 may be large, the material of the container body 10 may be a metallic material such as aluminum or stainless steel. However, the container body 10 may be formed of a material that is more likely to deform than the storage member 60 due to temperature changes or internal pressure changes in the internal space.

[0016] The container body 10 is formed in a cylindrical shape so as to enclose the internal space 11. The container body 10 is formed, for example, in a cylindrical shape or a regular polygonal cylindrical shape such that the pressure of the gas is uniformly distributed within the internal space 11. The container body 10, and thus the internal space 11, extends in the axial direction. Also, the container body 10 is formed so as to have a reduced diameter from the axial center side to the axial end side at both axial ends. Further, the container body 10 is formed so as to bend from both axial ends toward the internal space 11 side in the axial direction, resulting in a recess. The internal space 11 is formed in a columnar shape along the inner surface of the container body 10.

[0017] The container body 10 has a straight portion 14 and dome portions 15, 16. The straight portion 14 is a portion that extends in the axial direction at the axial center of the container body 10 and is formed in a cylindrical shape (for example, a cylindrical shape). The dome portions 15, 16 are portions that are formed in a dome shape (for example, a hemispherical shell shape) at both axial ends of the container body 10. The container body 10 is arranged in a continuous order of dome portion 15 → straight portion 14 → dome portion 16 from one axial end side to the other axial end side.

[0018] The container body 10 has openings 12, 13. The opening 12 is a portion that opens at one axial end of the container body 10. The opening 13 is a portion that opens at the other axial end of the container body 10. The openings 12, 13 are provided in the dome portions 15, 16 of the container body 10. A base 20 is inserted into the opening 12. Also, a base 30 is inserted into the opening 13.

[0019] The caps 20 and 30 are members that allow gas to enter and exit between the internal space 11 of the container body 10 and the outside. That is, the caps 20 and 30 are used for introducing gas from the outside of the container body 10 into the internal space 11 and discharging gas from the internal space 11 to the outside of the container body 10. The caps 20 and 30 are attached to the axial end portions of the container body 10. A sealing member such as an O-ring is interposed between the caps 20 and 30 and the container body 10 to prevent gas leakage from the internal space 11 of the container body 10 to the outside. The caps 20 and 30 are formed of a metal such as aluminum or stainless steel to ensure rigidity.

[0020] The caps 20 and 30 have communication passages 21 and 31. The communication passages 21 and 31 are passages that communicate the internal space of the container body 10 to the outside. The communication passages 21 and 31 are connected to a gas pipe and a valve (not shown).

[0021] Note that the gas container 1 may allow gas to enter and exit through both of the communication passages 21 and 31 of the caps 20 and 30, or as shown in FIG. 2, it may allow gas to enter and exit through only one of them (specifically, the communication passage 31) while a plug is attached to the other (specifically, the communication passage 21). Further, the gas container 1 may have a cap 20 or a cap 30 for allowing gas to enter and exit attached to either one of the axial end portions of the container body 10. Also, the caps 20 and 30 may function as a heat exchanger through which a heat exchange medium circulates for temperature adjustment of the gas container 1.

[0022] Further, the container body 10 is formed separately from the caps 20 and 30 and is integrated with the caps 20 and 30 by inserting the formed caps 20 and 30. Note that the container body 10 may be integrally formed with the caps 20 and 30 by, for example, insert molding.

[0023] The reinforcing member 40 is a member that covers the radially outer surface of the container body 10 to reinforce the container body 10. The reinforcing member 40 is preferably used particularly when the gas container 1 is a pressure-resistant container. The reinforcing member 40 is composed of, for example, high-strength fibers impregnated with resin (i.e., FRP). The high-strength fibers are, for example, carbon fibers, glass fibers, aramid fibers, etc. The resin impregnated in the high-strength fibers is a thermosetting resin such as epoxy resin, unsaturated polyester resin, vinyl ester resin, etc.

[0024] The reinforcing member 40 may be formed, for example, as a helical layer or a hoop layer by winding high-strength fibers impregnated with resin around the outer surface of the container body 10, or may be formed by attaching a helical layer or a hoop layer formed in a sheet shape using resin and high-strength fibers to the outer surface of the container body 10. Further, the reinforcing member 40 may be one in which the resin is heat-cured after the formation of the helical layer or the hoop layer.

[0025] The storage member 60 is a member that stores and releases gas. The storage member 60 is housed in the internal space 11 of the container body 10 and is held by the container body 10. The storage member 60 is formed in a columnar shape following the shape of the internal space 11. The storage member 60 extends in the axial direction. The cross-section obtained by cutting the storage member 60 with a plane perpendicular to the axial direction corresponds to the cross-section of the internal space 11. The storage member 60 is formed of a material corresponding to the type of gas to be stored. The material of the storage member 60 is, for example, a porous carbon material such as carbon nanotubes, a porous metal complex (i.e., MOF), zeolite, a hydrogen storage alloy, a metal hydride, etc.

[0026] The storage member 60 may be formed in a solid state of powder such as primary particles or secondary particles, that is, in a pellet shape. According to the pellet-shaped storage member 60, a large contact area of the storage member 60 with respect to the gas can be ensured, so that the occlusion and release performance of the gas can be improved. Incidentally, the volume of the storage member 60 is preferably close to 100% with respect to the volume of the internal space 11 in order to ensure the gas storage amount, but may be 90% or more. The storage member 60 is formed by cross-linking the powder of the storage member material with a cross-linking agent or binding it with a binder. The cross-linking agent and the binder are formed of, for example, silicon-based, epoxy-based, or amine-based materials.

[0027] Incidentally, the storage member 60 may have performance that varies according to the axial position. For example, the storage member 60 may be configured such that the damage resistance at the axial end portion is higher than that at the axial center portion. This damage resistance may be an index indicating the difficulty of powdering the storage member 60 solidified with powder. This damage resistance can be rephrased as strength, rigidity, abrasion resistance, viscosity, elastic force, etc.

[0028] Incidentally, when the amount of the cross-linking agent or the like that cross-links the material powder of the storage member 60 increases, the amount of the storage member 60 that can be accommodated in the accommodation space 52 decreases by that amount, and the amount of gas that the storage member 60 can store decreases, resulting in a decrease in the occlusion and release performance of the storage member 60. Therefore, in the storage member 60, the fact that the damage resistance at the axial end portion is higher than that at the axial center portion is synonymous with the fact that the occlusion and release performance at the axial end portion is lower than that at the axial center portion.

[0029] The storage member 60 is formed along the inner surfaces of the straight portion 14 and the dome portions 15, 16 of the container body 10. The storage member 60 is assembled and integrated with the container body 10 by insert molding. The storage member 60 has a straight corresponding portion 61 corresponding to the straight portion 14 and dome corresponding portions 62, 63 corresponding to the dome portions 15, 16.

[0030] The straight portion corresponding part 61 is a portion formed in a columnar shape (for example, a cylindrical shape) extending in the axial direction at the central portion of the storage member 60 in the axial direction. The radially outer surface of the straight portion corresponding part 61 faces the radially inner surface of the straight portion 14 of the container body 10 in the radial direction. Incidentally, as shown in FIG. 2, the straight portion corresponding part 61 may be provided with a cavity portion 61a for inserting a shaft member at the axial center portion. This shaft member is a member for rotating the container body 10 during the formation of the reinforcing member 40 (for example, molding by the filament winding method). Further, the cavity portion 61a may have the same diameter as the diameters of the communication passages 21 and 31 of the caps 20 and 30. Also, the axial end surfaces of the straight portion corresponding part 61 may be in contact with the axial inner surfaces of the caps 20 and 30 when the caps 20 and 30 are attached to the container body 10.

[0031] The dome corresponding parts 62 and 63 are portions formed in a dome shape (for example, a hemispherical shape) at both axial ends of the storage member 60. The curved outer surfaces of the dome corresponding parts 62 and 63 face the curved inner surfaces of the dome portions 15 and 16 of the container body 10. Incidentally, the dome corresponding parts 62 and 63 may be formed in a hoop shape like a hemisphere excluding the insertion portions of the caps 20 and 30. The dome corresponding parts 62 and 63 protrude axially outward from the axial end surfaces of the straight portion corresponding part 61.

[0032] As shown in FIGS. 2, 3, and 4, the storage member 60 has a recess 64. The recess 64 is a portion provided on the outer surface of the storage member 60 (specifically, the radially outer surface of the straight portion corresponding part 61) and recessed inward (specifically, radially inward). Incidentally, the recess 64 may be provided on the outer surfaces of the dome corresponding parts 62 and 63.

[0033] As shown in FIGS. 2, 3, and 5, the container body 10 has a protrusion 17. The protrusion 17 is a portion provided on the inner surface of the container body 10 (specifically, the radially inner surface of the straight portion 14) and protruding outward (specifically, radially outward). Incidentally, the protrusion 17 may be provided on the outer surfaces of the dome portions 15 and 16.

[0034] The concave portion 64 of the storage member 60 and the convex portion 17 of the container body 10 are engaged with each other. The engagement between the concave portion 64 and the convex portion 17 is performed so that the storage member 60 is restricted from moving axially with respect to the container body 10 in the internal space 11 and is restricted from rotating about the axis center. The concave portion 64 has an axially facing axial end face and a rotation direction end face facing in the rotation direction about the axis center. The convex portion 17 has an axially facing axial end face and a rotation direction end face facing in the rotation direction about the axis center. The axial end faces of the concave portion 64 and the convex portion 17 face each other without inclining with respect to the axial direction, and the rotation direction end faces of the concave portion 64 and the convex portion 17 face each other without inclining with respect to the rotation direction.

[0035] In addition, the concave portion 64 may be provided at one location on the outer surface of the storage member 60, or may be provided at a plurality of locations in a scattered manner. Further, the convex portion 17 may be provided at one location on the inner surface of the container body 10, or may be provided at a plurality of locations in a scattered manner. And in the structure where the concave portion 64 and the convex portion 17 are provided at a plurality of locations respectively, a plurality of concave portions 64 and convex portions 17 may be arranged at intervals in the axial direction, as shown in FIGS. 2, 4, and 5, or may be arranged at intervals in the rotation direction.

[0036] Also, the concave portion 64 and the convex portion 17 are formed such that when the container body 10 and the storage member 60 are deformed due to an increase in the temperature or an increase in the internal pressure of the internal space 11, the state in which the concave portion 64 and the convex portion 17 are engaged with each other continues. Incidentally, the formation of the concave portion 64 and the convex portion 17 is set in consideration of, in particular, the difference in the amount of deformation between the container body 10 and the storage member 60 when the highest temperature and the maximum internal pressure assumed in the internal space 11 occur.

[0037] For example, as shown in FIG. 3, the convex portion 17 is formed such that the length H from the general surface of the radially inner surface of the container body 10 to the tip of the convex portion 17 is larger than the radial distance Smax between the general surface of the radially inner surface of the container body 10 and the general surface of the radially outer surface of the storage member 60 when the highest temperature and the maximum internal pressure assumed in the internal space 11 occur.

[0038] Hereinafter, an example of a method for manufacturing the gas container 1 will be described. First, a pellet-shaped storage member 60 in which a straight portion corresponding part 61 and dome corresponding parts 62 and 63 are formed is prepared. Then, the storage member 60 is insert-placed in a molding die for molding the container body 10, and the container body 10 is insert-molded by pouring a liner resin.

[0039] Next, the bases 20 and 30 are attached to the insert-molded container body 10 together with a sealing member, and a shaft member for rotating the container body 10 is inserted into the cavity 61a through the communication passage 31 of the base 30. Then, the outer surface of the container body 10 is coated with a reinforcing member 40 by the filament winding (FW) method. Finally, the shaft member is removed from the cavity 61a to manufacture the gas container 1.

[0040] The operation of the gas container 1 will be described. In the gas container 1, a storage member 60 that stores and releases gas is disposed in the internal space 11 of the container body 10. The storage member 60 has a recess 64 provided on the radially outer surface. The container body 10 has a protrusion 17 provided on the radially inner surface. The recess 64 of the storage member 60 and the protrusion 17 of the container body 10 are engaged with each other. This engagement is performed so that the storage member 60 is restricted from moving axially with respect to the container body 10 in the internal space 11 and from rotating around the axis center.

[0041] Therefore, according to the gas container 1, the storage member 60 can be restricted from moving axially with respect to the container body 10 in the internal space 11 and from rotating in the rotational direction, so that the fixed holding of the storage member 60 in the internal space 11 (specifically, the fixed holding in both the axial direction and the rotational direction) can be realized.

[0042] In addition, in order to accommodate the storage member 60 in the internal space 11 of the container body 10, it is not necessary to use a separate accommodating member for holding the storage member 60 in the internal space 11. That is, the storage member 60 is directly accommodated in the internal space 11 of the container body 10 and is fixedly held to the container body 10 by the engagement between the concave portion 64 and the convex portion 17. According to this structure, since the volume occupied by the storage member 60 in the internal space 11 can be increased, the gas storage amount in the internal space 11 can be increased. Further, since there is no member that inhibits heat conduction such as the above-described accommodating member in the internal space 11, thermal uniformity can be achieved throughout the internal space 11, the temperature of the storage member 60 can be made uniform, and the occlusion and release performance of the storage member 60 can be improved.

[0043] Therefore, according to the gas container 1, while sufficiently ensuring the gas storage amount in the internal space 11 of the container body 10, the fixed holding of the storage member 60 can be realized.

[0044] In the gas container 1, the concave portion 64 of the storage member 60 and the convex portion 17 of the container body 10 are engaged with each other as described above. The concave portion 64 and the convex portion 17 are formed such that when the container body 10 and the storage member 60 are each deformed due to a temperature rise or an internal pressure rise in the internal space 11, the state in which the concave portion 64 and the convex portion 17 are engaged with each other continues. For this reason, even when the container body 10 and the storage member 60 (particularly, the container body 10) are deformed to the maximum extent, the state in which the concave portion 64 and the convex portion 17 are engaged with each other is not released and the convex portion 17 does not come out of the concave portion 64. Therefore, the storage member 60 can be fixedly held to the container body 10, and it is possible to reliably prevent the storage member 60 from relatively moving or rotating with respect to the container body 10 in the internal space 11.

[0045] In the gas container 1, the container body 10 has a straight portion 14 formed in a cylindrical shape at the central portion in the axial direction, and dome portions 15 and 16 formed in a dome shape at both axial ends. The storage member 60 is formed along the inner surfaces of the straight portion 14 and the dome portions 15 and 16, and has a straight corresponding portion 61 and dome corresponding portions 62 and 63. That is, the storage member 60 has not only the straight corresponding portion 61 along the inner surface of the straight portion 14 of the container body 10, but also the dome corresponding portions 62 and 63 along the inner surfaces of the dome portions 15 and 16 of the container body 10.

[0046] In this structure, when the storage member 60 attempts to move radially with respect to the container body 10 in the internal space 11, its movement is restricted by the contact between the straight portion 14 and the straight corresponding portion 61 and the contact between the dome portions 15 and 16 and the dome corresponding portions 62 and 63. Also, when the storage member 60 attempts to move axially with respect to the container body 10 in the internal space 11, its movement is restricted by the contact between the dome portions 15 and 16 and the dome corresponding portions 62 and 63. Therefore, according to the gas container 1, it is possible to restrict the storage member 60 from moving not only radially but also axially with respect to the container body 10 in the internal space 11, so that the fixing and holding function of the storage member 60 in the internal space 11 can be improved.

[0047] Also, in the above structure, the storage member 60 is accommodated in the internal space 11 of the container body 10 with almost no gap generated between the storage member 60 and the container body 10. Therefore, the amount of gas that can be stored in the internal space 11 using the storage member 60 can be maximized, so that the gas absorption and release efficiency of the gas container 1 can be increased.

[0048] Furthermore, in the gas container 1, the storage member 60 is assembled to the container body 10 by insert molding. Therefore, the storage member 60 can be reliably accommodated and arranged in the internal space 11 of the container body 10, and the accommodation and arrangement can be realized with almost no gap generated between the outer surface of the storage member 60 and the inner surface of the container body 10.

[0049] In the gas container 1, when gas is supplied into the internal space 11 of the container body 10 through the base 30, the gas first flows in the axial direction toward the base 20 side in the internal space 11 through the cavity 61a of the storage member 60. The gas flowing into the internal space 11 is gradually occluded by the radially outward storage member 60 while passing through the cavity 61a. Therefore, according to the gas container 1, the gas can be evenly distributed throughout the entire internal space 11, and the gas concentration can be equalized. As a result, the occlusion and release performance of the gas in the storage member 60 can be fully utilized to improve its storage and release performance.

[0050] Incidentally, in the above embodiment, the engagement between the concave portion 64 of the storage member 60 and the convex portion 17 of the container body 10 is performed so as to restrict the axial movement of the storage member 60 relative to the container body 10 in the internal space 11 and restrict the rotation about the axis center. However, the present invention is not limited to this.

[0051] For example, when the storage member 60 is allowed to rotate in the rotational direction relative to the container body 10 in the internal space 11, at least the concave portion 64 of the concave portion 64 and the convex portion 17 may be provided annularly in the rotational direction so as to be able to rotate. Further, when the storage member 60 is allowed to move axially relative to the container body 10 in the internal space 11, at least the concave portion 64 of the concave portion 64 and the convex portion 17 may be provided to extend linearly in the axial direction so as to be able to move axially. Furthermore, when the storage member 60 is allowed to move in the spiral direction relative to the container body 10 in the internal space 11, at least the concave portion 64 of the concave portion 64 and the convex portion 17 may be provided to extend spirally with respect to the axial direction so as to be able to move in the spiral direction.

[0052] Also, in the above-described embodiment, the container body 10 is insert-molded with the storage member 60 inserted therein, and the storage member 60 is assembled and integrated with the container body 10 by insert molding. However, the present invention is not limited to this, and the container body 10 may be formed by integrating a cylindrical split body and a dome-shaped split body, each formed by injection molding or the like, by welding or the like. In this modified form, the storage member 60 may be assembled to the cylindrical split body and the dome-shaped split body on one side in the axial direction, and then the dome-shaped split body on the other side in the axial direction may be welded to the cylindrical split body, whereby the storage member 60 may be integrated with the container body 10.

[0053] Note that the present invention is not limited to the above-described embodiments and the like, and various modifications can be made without departing from the spirit of the present invention.

Explanation of Reference Numerals

[0054] 1: Gas container, 10: Container body, 11: Internal space, 14: Straight portion, 15, 16: Dome portions, 17: Convex portion, 20, 30: Base, 60: Storage member, 61: Straight-corresponding portion, 62, 63: Dome-corresponding portions, 64: Concave portion.

Claims

1. A cylindrical container body having an internal space for storing gas, A base attached to an axial end of the container body and having a communication passage for communicating the internal space to the outside of the container body, A storage member disposed in the internal space for absorbing and releasing gas, comprising The storage member has either a concave portion or a convex portion provided on a radially outer surface thereof and engaging with each other, The container body has the other of the concave portion and the convex portion provided on a radially inner surface thereof, The concave portion and the convex portion are formed such that axial movement of the storage member with respect to the container body is restricted and rotation about the axial center is restricted. A gas container.

2. The gas container according to claim 1, wherein the storage member is assembled to the container body by insert molding.

3. A cylindrical container body having an internal space for storing gas, A base attached to an axial end of the container body and having a communication passage for communicating the internal space to the outside of the container body, A storage member disposed in the internal space for absorbing and releasing gas, comprising The storage member has either a concave portion or a convex portion provided on a radially outer surface thereof and engaging with each other, The container body has the other of the concave portion and the convex portion provided on a radially inner surface thereof, The storage member is assembled to the container body by insert molding. A gas container.

4. The container body is more likely to deform than the storage member due to a temperature change or an internal pressure change in the internal space, The concave portion and the convex portion are formed such that a state in which the concave portion and the convex portion engage with each other continues when the container body and the storage member are each deformed. The gas container according to any one of claims 1 to 3.

5. The container body has a straight portion formed in a cylindrical shape at the central portion in the axial direction and dome portions formed in a dome shape at both axial ends. The storage member is formed along the inner surfaces of the straight portion and the dome portions, and the gas container according to any one of claims 1 to 4.

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