Mouth structure and pressure container

Abstract

The present invention includes: a boss part that forms the circumferential edge of an opening formed in a hollow container body; a fastening ring that is locked onto the boss part in a slidable manner; and a closure part that closes the opening formed in the container body by being connected to the boss part. The fastening ring locked to the boss part and the closure part are fastened together by using a prescribed fastening means, thereby connecting the boss part and the closure part with the fastening ring therebetween.

Description

Mouth structure, pressure vessel

[0001] The present invention relates to a nozzle structure and a pressure vessel.

[0002] Pressure vessels are known that are filled with pressurized substances such as compressed or liquefied gases, such as liquid hydrogen or compressed natural gas.

[0003] For example, Patent Document 1 describes such a container. Patent Document 1 describes a pressure-resistant container comprising a multi-layered container body, a metal port member (boss portion) provided at an end of the container body, and a metal container valve mounting member or container valve (closure portion) attached to the port member. According to Patent Document 1, the port member and the container valve mounting member or container valve are connected by fastening a flange formed on the port member to a flange formed on the container valve mounting member with a plurality of bolts and nuts.

[0004] Japanese Patent Application Laid-Open No. 2001-214998

[0005] When the boss (port member) is made of metal as described in Patent Document 1, the liner forming the inner surface of the vessel is made of resin, resulting in a large difference in thermal expansion between the boss and the liner. As a result, when the pressurized substance filled inside the vessel is a cryogenic fluid such as liquid hydrogen, the difference in thermal expansion between the materials can damage the liner inlet, resulting in a loss of airtightness. On the other hand, if the boss is simply made of resin to resolve this issue, the closure (vessel valve mounting member) is made of metal to reduce thermal stress with the connecting piping, which in turn increases the difference in thermal expansion between the boss and the closure. As a result, there is a risk of damage at a location other than the liner inlet. For example, as described above, there has been a problem in that it is sometimes difficult to reduce the risk of damage in pressure vessels filled with pressurized substances.

[0006] Therefore, one of the objects of the present invention is to provide a mouth structure that can solve the above-mentioned problems.

[0007] In order to achieve this purpose, the mouth structure, which is one form of the present disclosure, includes a boss portion that forms the periphery of an opening formed in a hollow container body, a fastening ring that is engaged in a slidable state relative to the boss portion, and a closure portion that closes the opening formed in the container body by being connected to the boss portion, and is configured such that the fastening ring engaged with the boss portion and the closure portion are fastened together using a predetermined fastening means, thereby connecting the boss portion and the closure portion via the fastening ring.

[0008] Furthermore, a pressure vessel according to another embodiment of the present disclosure includes a boss portion forming the periphery of an opening formed in a hollow vessel body, a fastening ring slidably engaged with the boss portion, and a closure portion that closes the opening formed in the vessel body by being connected to the boss portion, and the fastening ring engaged with the boss portion and the closure portion are fastened together using a predetermined fastening means to form a mouth structure that connects the boss portion and the closure portion via the fastening ring; and the vessel body.

[0009] According to the above-described configurations, the risk of breakage in a pressure vessel filled with a pressurized substance can be reduced.

[0010] FIG. 1 is a diagram showing an example configuration of a pressure vessel according to a first embodiment of the present disclosure; FIG. 2 is a diagram showing an example configuration of a nozzle structure; FIG. 3 is a diagram for explaining the relationship between the amounts of thermal shrinkage; FIG. 4 is a diagram for explaining the relationship between the amounts of thermal shrinkage; FIG. 5 is a diagram showing an example material for each component included in the nozzle structure; FIG. 6 is a diagram showing an example physical property relationship between a boss portion, a liner portion, and an adhesive; FIG. 7 is a diagram showing an example dimension of each component included in the nozzle structure; FIG. 8 is a diagram showing another example configuration of the nozzle structure.

[0011] [First embodiment] A first embodiment of the present disclosure will be described with reference to Figs. 1 to 9. Fig. 1 is a diagram showing an example of the configuration of a pressure vessel 10. Fig. 2 is a diagram showing an example of the configuration of a neck structure 200. Figs. 3 to 5 are diagrams for explaining the relationship between the amount of thermal shrinkage. Fig. 6 is a diagram showing example materials for each component included in the neck structure 200. Fig. 7 is a diagram showing an example of the physical property relationship between the boss portion 210, the liner portion 120, and the adhesive. Fig. 8 is a diagram showing example dimensions of each component included in the neck structure 200. Fig. 9 is a diagram showing another example of the configuration of the neck structure 200.

[0012] In a first embodiment of the present disclosure, a pressure vessel 10 capable of being filled with a cryogenic fluid such as liquid hydrogen as a pressurized substance will be described. As shown in Fig. 1, the pressure vessel 10 has a mouth structure 200 that can connect a boss portion 210 and a closure portion 230 via a fastening ring 220. For example, the fastening ring 220 is configured to be engaged with the boss portion 210 in a state in which it can slide axially and radially. Furthermore, when engaged with the boss portion 210, the fastening ring 220 functions as a flange of the boss portion 210. With this configuration, when fastening ring 220 engaged with boss portion 210 and flange 231 of closure portion 230 are in contact with or close to each other, fastening ring 220 and closure portion 230 can be fastened together using fastening means 240 such as bolts and nuts (fastening means 240-1, fastening means 240-2, .... hereinafter, referred to as fastening means 240 unless otherwise distinguished), thereby connecting boss portion 210 and closure portion 230 via fastening ring 220. As a result, even if the linear expansion coefficients of the components such as boss portion 210, fastening ring 220, and closure portion 230 are different, thermal stress can be alleviated by the sliding of fastening ring 220, etc.

[0013] Note that fastening ring 220 may be slidably engaged with boss portion 210 by any means. For example, fastening ring 220 can be slidably engaged with boss portion 210 by fitting convex portion 222 of fastening ring 220 into groove 213 formed on the outer circumferential surface of boss portion 210. Fastening ring 220 may also be engaged by a method other than those exemplified above, such as by fastening using fastening means such as bolts and nuts to slidably engage with boss portion 210.

[0014] 1 is a cross-sectional view schematically illustrating the structure near the end of a pressure vessel 10 described in the present disclosure. Referring to FIG. 1, the pressure vessel 10 in the present disclosure includes a vessel body 100 and a neck structure 200.

[0015] The container body 100 has a hollow structure with an opening. For example, the container body 100 has a cylindrical or spherical shape with at least one of both axial ends open. The inside of the container body 100 can be filled with a cryogenic fluid such as liquid hydrogen. As shown in FIG. 1 , the container body 100 includes an outer layer 110 and a liner portion 120.

[0016] The outer layer 110 is a layer formed of fiber reinforced plastics (FRP). Specifically, the outer layer 110 is formed of carbon fiber reinforced plastics (CFRP) containing carbon fiber and resin, for example. The outer layer 110 can be formed by, for example, winding a CFRP layer around the outer periphery of the liner portion 120 so as to cover the outer periphery of the liner portion 120.

[0017] The liner portion 120 is formed of any resin or the like having gas barrier properties. As will be described later, the type of material, such as the resin, that forms the liner portion 120 can be determined depending on the relationship with the boss portion 210 and the adhesive or the like used to bond the boss portion 210 and the liner portion 120.

[0018] As described above, the outer layer 110 covers the outer periphery of the liner portion 120. In other words, the liner portion 120 can be said to cover the inner periphery of the outer layer 110, and can also be said to cover the inner surface of the container body 100.

[0019] For example, the container body 100 includes the above-described outer layer 110 and liner portion 120. Furthermore, as shown in Fig. 1, a mouth structure 200 is formed on at least one of the open axial ends of the container body 100.

[0020] The neck structure 200 is bonded to the container body 100 at one end and has a structure that allows connection to piping or the like at the other end. For example, the neck structure 200 is bonded to the liner portion 120 using an adhesive while abutting against the liner portion 120 inside the container body 100. The neck structure 200 also penetrates an opening formed in the container body 100 along the axial direction of the container body 100 from the inside to the outside of the container body 100, allowing connection to piping or the like outside the container body 100. FIG. 2 is an enlarged cross-sectional view schematically showing an example structure near the end of the container body 100, illustrating an example configuration of the neck structure 200. Referring to FIG. 2, the neck structure 200 includes, for example, a boss portion 210, a fastening ring 220, a closure portion 230, a fastening means 240, and an O-ring 250.

[0021] The boss portion 210 forms the periphery of the opening formed in the container body 100. For example, the boss portion 210 includes a cylindrical portion 211 formed in a direction along the axial direction of the container body 100, and an umbrella portion 212 formed at a side end portion of the cylindrical portion 211 present inside the container body 100 and used when winding the liner portion 120, the outer layer 110, etc.

[0022] The cylindrical portion 211 has, for example, a cylindrical shape coaxial with the container body 100, and passes through an opening formed in the container body 100 along the axial direction of the container body 100 from the inside to the outside of the container body 100. As described above, the umbrella portion 212 is formed on the side end of the cylindrical portion 211 that is inside the container body 100. The umbrella portion 212 abuts against the liner portion 120, and the umbrella portion 212 and the liner portion 120 are bonded together in abutting contact state using a predetermined adhesive.

[0023] Furthermore, grooves 213 are formed on the outer peripheral surface of the cylindrical portion 211, into which the protruding portions 222 formed on the fastening ring 220 are fitted. For example, the grooves 213 are band-shaped recesses that are formed in predetermined locations on the cylindrical portion 211 that are exposed to the outside of the container body 100 and that go around the outer peripheral surface of the cylindrical portion 211 (boss portion 210). Note that the grooves 213 do not necessarily have to go around the entire outer peripheral surface of the cylindrical portion 211. For example, the grooves 213 may be recesses, such as rectangular pillar-shaped recesses, formed in multiple locations along the circumferential direction.

[0024] The fastening ring 220 can be locked onto the boss portion 210 in a state where it can slide circumferentially and radially relative to the boss portion 210, and functions as a flange that abuts against or is close to the closure portion 230 when locked onto the boss portion 210. For example, the fastening ring 220 includes a cylindrical ring portion 221 having an inner diameter that is equal to or slightly larger than the outer diameter of the boss portion 210, a convex portion 222 that fits into the groove 213, and a flange portion 223 that functions as a flange that abuts against or is close to the closure portion 230.

[0025] The convex portion 222 is a portion of the ring portion 221 that protrudes radially inward from the inner circumferential surface of the ring portion 221 near the side end portion of the ring portion 221 that is closer to the container body 100. The shape of the convex portion 222 may correspond to the shape of the groove 213. For example, if the groove 213 is a band-shaped recess that circles the outer circumferential surface of the tubular portion 211, the convex portion 222 may be a band-shaped convex portion that circles the inner circumferential surface of the fastening ring 220. Furthermore, if the groove 213 is a plurality of recesses formed along the circumferential direction, the convex portion 222 may be a convex portion that has a shape that corresponds to the recesses and is located at a position that corresponds to the recesses.

[0026] The flange portion 223 is a portion of the ring portion 221 that protrudes radially outward from the outer peripheral surface of the ring portion 221 at the end opposite the side where the convex portion 222 is formed when viewed in the axial direction. For example, the flange portion 223 is formed in a flat plate shape. Furthermore, a plurality of bolt through-holes 224 that axially penetrate the flange portion 223 are formed at predetermined locations of the flange portion 223. Fastening means 240 such as bolts are inserted into the bolt through-holes 224 when fastening the fastening ring 220 having the flange portion 223 to the closure portion 230. Any number of bolt through-holes 224 may be formed in the flange portion 223. The inner diameter of the bolt through-hole 224 may be equal to or slightly larger than the outer diameter of the bolt, which is the fastening means 240. In other words, the size of the bolt through-hole 224 may be determined depending on the thickness of the fastening means 240, etc.

[0027] The fastening ring 220 includes the ring portion 221, the convex portion 222, and the flange portion 223 as described above. The fastening ring 220 can be configured to be separable into multiple pieces. For example, the fastening ring 220 may be formed into a cylindrical ring portion 221 by combining two divided kamaboko-shaped pieces. The multiple divided pieces of the fastening ring 220 may then be fastened together using any means such as bolts and nuts, thereby fitting the convex portion 222 into the groove 213 and slidably engaging with the boss portion 210.

[0028] The closure portion 230 is a member that can be connected to the boss portion 210 via the fastening ring 220. The closure portion 230 can close the opening formed in the container body 100 by connecting to the boss portion 210. Furthermore, the closure portion 230 can be connected to piping used for filling / supplying cryogenic fluid such as liquid hydrogen. For example, SUS (Steel Special Use Stainless) piping or the like may be connected to the closure portion 230. Piping other than the above examples may also be connected to the closure portion 230.

[0029] As described above, the closure portion 230 is formed with a flange 231. For example, the flange 231 is formed in a flat plate shape. Furthermore, a plurality of bolt through-holes 232 that axially penetrate the flange 231 are formed at predetermined locations of the flange 231. For example, the bolt through-holes 232 are formed at positions on the flange 231 that correspond to the positions of the bolt through-holes 224 formed in the flange portion 223. When fastening the fastening ring 220 and the closure portion 230 together, fastening means 240 such as bolts are inserted into the bolt through-holes 232. Note that any number of bolt through-holes 232 may be formed in the flange 231. Furthermore, the relationship between the bolt through-holes 232 and the fastening means 240 may be the same as that between the bolt through-holes 224.

[0030] Furthermore, a recess 233 for installing an O-ring 250, which is a sealing material, can be formed at a predetermined location on the surface of the closure portion 230 that abuts against the boss portion 210 when the closure portion 230 and the boss portion 210 are connected via the fastening ring 220. Here, the O-ring 250 is a member that prevents leakage of the pressurized substance filled inside the container body 100 and the intrusion of foreign matter from the outside. When the closure portion 230 and the boss portion 210 are connected via the fastening ring 220, the O-ring 250 is crushed by the closure portion 230 and the boss portion 210, thereby improving airtightness, etc.

[0031] For example, the mouth structure 200 includes the boss portion 210, the fastening ring 220, the closure portion 230, the fastening means 240, and the O-ring 250, as described above.

[0032] As mentioned above, the inside of the container body 100 is filled with a cryogenic fluid such as liquid hydrogen. Therefore, when selecting materials for each component, it is desirable to pay attention to the following points: (1) The linear expansion coefficients of the liner portion 120, the boss portion 210, and the adhesive that bonds them are sufficiently close. (2) The amount of thermal contraction of the fastening means 240 (bolt) is equal to or greater than the sum of the amounts of thermal contraction of the boss portion 210 and the closure portion 230.

[0033] If the setting in (1) above is inadequate, the liner portion 120, the boss portion 210, or the adhesive may be damaged when a cryogenic fluid such as liquid hydrogen is filled, resulting in a loss of airtightness. Also, if the setting in (2) above is inadequate, the axial force of the fastening means 240 may decrease, resulting in a loss of airtightness. Each condition will be described in more detail below.

[0034] (1) The linear expansion coefficients of the liner portion 120, the boss portion 210, and the adhesive that bonds them are sufficiently close. For example, when completely joined parts x and y are cooled by Δt degrees, the elastic strain ε that occurs between x and y is calculated as follows, assuming that the thermal strain due to the difference in the linear expansion coefficient α is directly converted into elastic strain. In reality, the magnitude of the elastic strain that occurs varies depending on the cross-sectional area and the ratio of the elastic moduli of x and y. However, even if it does vary, it will not exceed the value obtained from the following formula. Therefore, by using the following formula, a safe evaluation can be made. ε ｘｙ = Δt × (α ｘ -α ｙ )

[0035] That is, the material b of the boss portion 210, the material l of the liner portion 120, and the material g of the adhesive used to bond the boss portion 210 and the liner portion 120 together should be selected so that the inequalities for the fracture strain S shown below all hold when the pressure vessel 10 is filled with cryogenic fluid. In other words, it is desirable to select the material b of the boss portion 210, the material l of the liner portion 120, and the material g of the adhesive so that the relationship between the linear expansion coefficients of the materials satisfies the condition shown in the following formula: S ｂ >Δt(α ｂ -α ｇ ) S ｇ >Δt(α ｇ -α ｂ ) S ｇ >Δt(α ｇ -α ｌ ) S ｌ >Δt(α ｌ -α ｇ )

[0036] For example, as described above, it is desirable that the material b of the boss portion 210, the material l of the liner portion 120, and the material g of the adhesive are selected so that the relationship in the linear expansion coefficient between each material satisfies predetermined conditions, such as satisfying the above-mentioned relationship.

[0037] (2) The amount of thermal contraction of the fastening means 240 (bolt) is equal to or greater than the sum of the amounts of thermal contraction of the boss portion 210 and the closure portion 230. To satisfy condition (2), when the pressure vessel 10 is cooled by Δt degrees (for example, from +23 degrees to -253 degrees) with the cryogenic fluid such as liquid hydrogen that is filled in it, the amount of change in each dimension should satisfy the formula shown in Equation 1 below. In other words, in the cooling process to the temperature difference Δt, the bolt / nut contraction amount ΔL ２ The amount of contraction ΔL between the flange 231 and the flange portion 223 １ The materials for each component and the dimensions may be selected so as to achieve the above.

[0038] In addition, L １ is shown in FIG. ２ 4 is shown. Also, as shown in FIG. 5, ΔL １ = ((L ｃａ -L ｃｂ ) × α ｃ +L ｂ ×α ｂ + (L ｒｂ -L ｒｃ ) × α ｒ ) × Δt ΔL ２ = (L ｃａ +L ｂ +L ｒｂ -L ｃｂ -L ｒｃ ) × α ｎ ×Δt. In addition, α ｎ : Linear expansion coefficient of bolt α ｃ : Linear expansion coefficient α of the closure portion 230 ｂ : Linear expansion coefficient α of boss portion 210 ｒ : coefficient of linear expansion of fastening ring 220

[0039] When selecting materials for each component and setting dimensions, it is desirable to pay attention to the above points (1) and (2).

[0040] In this way, the neck structure 200 is formed so that the boss portion 210 and the closure portion 230 can be connected via the fastening ring 220. With this configuration, even if the linear expansion coefficients of the components such as the boss portion 210, the fastening ring 220, and the closure portion 230 are different, thermal stress can be alleviated by sliding the fastening ring 220. As a result, the risk of damage can be reduced even when the pressure vessel 10 is filled with a cryogenic fluid such as liquid hydrogen.

[0041] Furthermore, fastening ring 220 is slidably secured to boss portion 210 by fitting convex portion 222 of fastening ring 220 into groove 213 formed on the outer circumferential surface of boss portion 210. With this configuration, fastening ring 220 can easily absorb thermal contraction in the circumferential and radial directions by sliding, thereby more easily reducing the risk of breakage.

[0042] Furthermore, according to the method exemplified in the present disclosure, the crushing force on the O-ring 250 can be easily adjusted by adjusting the tightening torque of the fastening means 240. As a result, the crushing force on the O-ring 250 can be appropriately controlled, and airtightness can be more reliably maintained.

[0043] The fastening means 240 may fasten the fastening ring 220 and the closure portion 230 together in a state in which the fastening means 240 is slidable, for example, in the radial direction relative to the fastening ring 220 and the closure portion 230. For example, the above state may be achieved by adjusting the size of the bolt through-holes 224 and the bolt through-holes 232 depending on the thickness of the fastening means 240 or by adjusting the tightening torque of the fastening means 240.

[0044] Example: A pressure vessel 10 including a nozzle structure 200 was actually fabricated by selecting materials for each component to satisfy the above-described conditions. FIG. 6 shows examples of materials for each component included in the nozzle structure 200. As an example, as shown in FIG. 6, PEI (polyetherimide), which has excellent low-temperature properties, was selected as the material for the boss portion 210. Furthermore, SNCM439 (nickel-chromium-molybdenum steel), which has high rigidity and high yield strength, was selected as the material for the fastening ring 220, and SUS304, a similar metal, was selected as the material for the closure portion 230 to reduce thermal stress with the SUS piping. Furthermore, PEI, which has a linear expansion coefficient similar to that of the boss portion 210, was selected as the fastening means 240, such as bolts and nuts, and a sealing material that can withstand extremely low temperatures was selected as the material for the O-ring 250.

[0045] FIG. 7 shows an example of a graph of the inequality of the fracture strain S corresponding to the condition (1) when the above-mentioned materials are selected. In the example shown in FIG. 7, S ｂ >Δt(α ｂ -α ｇ ) is established in the region indicated by the dashed line, and S ｇ >Δt(α ｇ -α ｂ The dotted line indicates the region where S ｇ >Δt(α ｇ -α ｌ ) is true, and the straight line indicates the region where S ｌ >Δt(α ｌ -α ｇ) is satisfied, as indicated by the dashed-dotted line. In the case of FIG. 7 , for example, by selecting an adhesive material such that the physical properties of the adhesive fall within the area sandwiched between the dashed-dotted lines, the area sandwiched between the dashed-dotted lines, and the area enclosed by both the straight and dashed lines, the risk of damage to the boss portion 210, the liner portion 120, and the adhesive can be reduced. For example, if a material with physical properties as shown in the plot of FIG. 7 is selected as the adhesive material, the boss portion 210 will not be damaged because the physical properties of the adhesive fall within the area sandwiched between the dashed-dotted lines. Furthermore, the liner portion 120 will not be damaged because the physical properties of the adhesive fall within the area sandwiched between the dashed-dotted lines. Furthermore, the adhesive itself will not be damaged because the physical properties of the adhesive fall within the area enclosed by both the straight and dashed lines.

[0046] In addition, when the above-mentioned materials are selected, the dimensions of each component are set so as to satisfy the formula corresponding to the condition (2) (see FIG. 8). ｂ Similarly, the length of L of the fastening ring 220 was set to 12 mm. ｒａ The length of L is set to 19.2 mm. ｒｂ Set the length of L to 3.5 mm. ｒｃ The length of L of the closure portion 230 was set to 17.7 mm. ｃａ Set the length of L to 25 mm. ｃｂ The length of each component was set to 8 mm. The dimensions of each component may have some error, as shown in FIG.

[0047] When the above-mentioned material is selected and the above-mentioned dimensions are set, the shrinkage amount ΔL １ is, for example, 0.153. ２ is 0.158. As a result, ΔL ２ -ΔL １ The value of is 0.005, which satisfies the formula 1.

[0048] A pressure vessel 10 was actually fabricated under the conditions exemplified above and subjected to a pressure test. As a result, when the vessel was filled with liquid hydrogen to a level of 50% or more, the measured burst pressure was 0.60 MPa, compared to the design target pressure of 0.45 MPa, confirming that the vessel was able to withstand pressures above the design target.

[0049] It should be noted that the examples are merely examples, and the materials and dimensions of each component included in the pressure vessel 10 described in this disclosure are not limited to those exemplified in the examples. The materials and dimensions of each component included in the pressure vessel 10 described in this disclosure may be selected and set arbitrarily as long as the combination satisfies the above-mentioned conditions.

[0050] <Other Configuration Examples> As described above, the fastening ring 220 may be fastened using fastening means such as bolts and nuts to be slidably engaged with the boss portion 210. FIG. 9 shows another configuration example of the mouth structure 200. Referring to FIG. 9, the mouth structure 200 may be composed of a boss portion 310, a fastening ring 320, a closure portion 330, fastening means 340, and an O-ring 350. In this configuration, as shown in FIG. 9, the fastening ring 320 and the closure portion 330 are fastened together using fastening means 340-1. Furthermore, the boss portion 310 and the fastening ring 320 are fastened together using fastening means 340-2. In this manner, the fastening ring 320 may be fastened to the boss portion 310.

[0051] In order to lock the fastening ring 320 in a slidable state relative to the boss portion 310, the size of the through-holes provided in the boss portion 310, the fastening ring 320, and the closure portion 330 for passing the fastening means 340 may be adjusted according to the thickness of the fastening means 340, or the tightening torque of the fastening means 340 may be adjusted. In the above-described configuration, as shown in Fig. 9, it is desirable to install an O-ring 350-1 on the surface where the fastening ring 320 and the closure portion 330 abut, and an O-ring 350-2 on the surface where the boss portion 310 and the fastening ring 320 abut. In other words, it is desirable to prepare an O-ring 350 for each of a plurality of abutting surfaces.

[0052] The pressure vessel 10 and the nozzle structure 200 exemplified in this disclosure can be used in various situations where pressure substances such as liquid hydrogen, which is a cryogenic fluid, are used. For example, the pressure vessel 10 and the nozzle structure 200 can be mounted on an electric aircraft or any other moving object having a liquid hydrogen propulsion system. The pressure vessel 10 and the nozzle structure 200 may also be used in situations and applications other than those exemplified above.

[0053] <Supplementary Notes> Part or all of the above-described embodiments can be described as follows: The mouth structure and other aspects of the present invention will be outlined below. However, the present invention is not limited to the following configuration.

[0054] (Appendix 1) A neck structure comprising: a boss portion forming the periphery of an opening formed in a hollow container body; a fastening ring slidably engaged with the boss portion; and a closure portion connected to the boss portion to close the opening formed in the container body, wherein the fastening ring engaged with the boss portion and the closure portion are fastened together using a predetermined fastening means, thereby connecting the boss portion and the closure portion via the fastening ring. (Appendix 2) The neck structure described in Appendix 1, wherein the fastening ring is slidably engaged with the boss portion by fitting a convex portion formed on an inner peripheral surface of the fastening ring into a groove formed in a portion of the boss portion exposed to the outside of the container body. (Appendix 3) The neck structure described in Appendix 1 or Appendix 2, wherein the fastening ring and the closure portion are fastened together using the fastening means with a flange portion formed on the fastening ring and a flange formed on the closure portion abutting or adjacent to each other, thereby connecting the boss portion and the closure portion via the fastening ring. (Supplementary Note 4) The neck structure according to any one of Supplementary Notes 1 to 3, wherein the boss portion is bonded to a liner portion covering the inner surface of the container body inside the container body, and the material of the boss portion, the material of the liner portion, and the material of the adhesive used to bond the boss portion and the liner portion are selected so that the relationship between the linear expansion coefficients of the materials satisfies a predetermined condition. (Supplementary Note 4-1) The neck structure according to Supplementary Note 4, wherein the material of the boss portion, the material of the liner portion, and the material of the adhesive used to bond the boss portion and the liner portion are selected so as to satisfy the following relational expression. S ｂ >Δt(α ｂ -α ｇ ) S ｇ >Δt(α ｇ -α ｂ ) S ｇ >Δt(α ｇ -α ｌ ) S ｌ >Δt(α ｌ -α ｇ) The boss material is b, the liner material is l, and the adhesive material is g. The breaking strain is S, the coefficient of linear expansion is α, and the container is cooled by Δt degrees by filling with cryogenic fluid. (Appendix 5) The materials of the fastening means, the boss portion, and the closure portion are selected, and the dimensions of the fastening means, the boss portion, and the closure portion are set so that the amount of thermal contraction of the fastening means due to the temperature difference caused by filling the container with the pressure substance is equal to or greater than the sum of the amounts of thermal contraction of the boss portion and the closure portion. A neck structure according to any one of Appendices 1 to 4. (Appendix 6) A pressure vessel comprising: a boss portion forming the periphery of an opening formed in a hollow vessel body; a fastening ring slidably engaged with the boss portion; and a closure portion that closes the opening formed in the vessel body by being connected to the boss portion, wherein the fastening ring engaged with the boss portion and the closure portion are fastened together using a predetermined fastening means to connect the boss portion and the closure portion via the fastening ring; and the vessel body.

[0055] In addition, some or all of the configurations described in Supplementary Notes 2 to 5 that are dependent on the nozzle structure described in Supplementary Note 1 may also be dependent on the pressure vessel described in Supplementary Note 6 in a similar dependent relationship.

[0056] Although the present invention has been described above with reference to the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

[0057] DESCRIPTION OF SYMBOLS 10 Pressure vessel 100 Vessel body 110 Outer layer 120 Liner portion 200 Mouth structure 210 Boss portion 211 Cylindrical portion 212 Umbrella portion 213 Groove 220 Fastening ring 221 Ring portion 222 Convex portion 223 Flange portion 224 Bolt-through hole 230 Closure portion 231 Flange 232 Bolt-through hole 233 Recess 240 Fastening means 250 O-ring 310 Boss portion 320 Fastening ring 330 Closure portion 340 Fastening means 350 O-ring

Claims

1. A mouth structure comprising: a boss portion forming the periphery of an opening formed in a hollow container body; a fastening ring that is engaged in a slidable state with respect to said boss portion; and a closure portion that closes the opening formed in said container body by being connected to said boss portion, wherein said fastening ring engaged with said boss portion and said closure portion are fastened together using a specified fastening means, thereby connecting said boss portion and said closure portion via said fastening ring.

2. The neck structure of claim 1, wherein the fastening ring is engaged in a slidable state relative to the boss portion by fitting a convex portion formed on the inner surface of the fastening ring into a groove formed in the portion of the boss portion exposed to the outside of the container body.

3. A mouth structure as described in claim 1, in which the fastening ring and the closure portion are fastened together using the fastening means while the flange portion formed on the fastening ring and the flange formed on the closure portion are in contact or close proximity to each other, thereby connecting the boss portion and the closure portion via the fastening ring.

4. The neck structure according to claim 1, wherein the boss portion is bonded to a liner portion that covers the inner surface of the container body inside the container body, and the material of the boss portion, the material of the liner portion, and the material of the adhesive used to bond the boss portion and the liner portion are selected so that the relationship between the linear expansion coefficients of the respective materials satisfies specified conditions.

5. A neck structure as described in claim 1, wherein the materials of the fastening means, the boss portion and the closure portion are selected and the dimensions of the fastening means, the boss portion and the closure portion are set so that the amount of thermal contraction of the fastening means due to the temperature difference caused by filling the container with the pressure substance is equal to or greater than the sum of the amounts of thermal contraction of the boss portion and the closure portion.

6. A pressure vessel comprising: a boss portion forming the periphery of an opening formed in a hollow vessel body; a fastening ring slidably engaged with said boss portion; and a closure portion that closes the opening formed in said vessel body by being connected to said boss portion, wherein said fastening ring engaged with said boss portion and said closure portion are fastened together using a predetermined fastening means to connect said boss portion and said closure portion via said fastening ring; and said vessel body.

Images