JP2005265138A - Pressure vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure vessel preventing generation of clearance between a liner made of synthetic resin and a mouthpiece, with optimum mouthpiece structure for high pressure gas sealing. <P>SOLUTION: The pressure vessel has a mouthpiece part, in which metal fittings exist on an inside containing gas in the liner 2 made of the synthetic resin and on an outside opposed thereto, in the form of interposing the liner made of the synthetic resin with a screw fastening mechanism, with inside and outside metal fitting members respectively comprising integrated components, and having a seal mechanism using a lip packing 10 in at least one part between an outer peripheral surface of the inside metal fitting member 7 and an inner peripheral surface of the liner made of the synthetic resin or between the inner peripheral surface of the outside metal fitting member 6 and the outer peripheral surface of the liner. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pressure vessel that stores a gas such as CNG (compressed natural gas), hydrogen, oxygen, and air under high pressure, and more particularly, to a structure of a base portion installed in the gas outlet portion.

  Conventionally, pressure vessels have been used for storage of various gases, and there are liner materials having a function of enclosing gas and those using metals and those using synthetic resins. When a metal is used for the liner material, the base part is also usually made of a metal that is integrally formed, and leakage of the contained gas from the base part is not a problem because it is integrally formed. On the other hand, when a synthetic resin is used as the liner material, the synthetic resin and the metal are joined to the base portion by various methods, but most of the storage pressure of the pressure vessel currently used is 20 MPa. Since it is assumed to be used under a low pressure as described below, leakage of the encapsulated gas from the joint is not a problem. For example, in Patent Document 1, a seal member is interposed between a corner portion on the inner peripheral surface of a liner and a base member provided by penetrating the liner on the inner peripheral side of the liner at the gas outlet portion of the liner. A structure that improves the airtight sealability is described.

However, in high-pressure hydrogen storage containers for fuel cells that have been in the spotlight in recent years, a high-pressure container that can withstand ultra-high pressure with a gaseous hydrogen filling pressure of about 50 to 70 MPa has been required. Furthermore, regulations on the air density (enclosed gas sealing degree) of containers are becoming more stringent from the safety and environmental aspects, and it is required to prevent leakage of the included gas and reduce the amount of leakage. The hydrogen leakage from the container is expected to be set to 1.0 cm ³ / hr · L or less.

As described above, in the conventional mechanism as described in Patent Document 1, there are two or more metal fittings installed from the outside of the base for the high pressure resistance requirement characteristics and the leakage regulations for recent pressure vessels. Even if it is made of a member or the metal fitting is formed of an integral member, the caulking fastening mechanism is employed, so that the radial position of the metal fitting relative to the synthetic resin liner cannot be fixed accurately. Therefore, when the sealing member installed between the synthetic resin liner and the metal fitting cannot fully demonstrate the sealing ability, and because the O-ring or flat packing is applied to the sealing member, the internal pressure increases. Further, since the deformation allowance of the packing is small, the ability to seal high-pressure gas was insufficient.
JP 2000-291887 A

  An object of the present invention is to provide a pressure vessel that can prevent the generation of a gap between a synthetic resin liner and a base metal fitting and has a base part structure particularly suitable for high-pressure gas sealing. is there.

In order to solve the above-described problems, the pressure vessel according to the present invention has the following requirements (A), (B), and (C) for a base portion installed in a gas outlet portion of a pressure vessel that stores gas. It consists of what is characterized by having all.
(A) Metal fittings provided in the base part are present on the inner side containing gas with respect to the synthetic resin liner and on the outer side relative to the inner side, and the inner and outer metal fitting members are fastened to each other by a screw mechanism. Take the form.
(B) The inner and outer metal members are each composed of an integral part.
(C) A seal mechanism using a lip packing between at least one portion between the outer peripheral surface of the inner metal member and the inner peripheral surface of the liner or between the inner peripheral surface of the outer metal member and the outer peripheral surface of the liner. Having.

  In the pressure vessel according to the present invention, a synthetic resin liner is sandwiched between the inner and outer metal fittings.

Further, in the pressure vessel according to the present invention, when the effective diameter of the screw is D (mm) and the screw fastening length is L (mm), the screw mechanism for fastening the inner and outer metal members is D and It is preferable that L satisfies the following relational expression.
L ≧ 0.05 × D

Further, in the state where the pressure vessel is projected in the axial direction, when the outer diameter of the flange portion of the inner metal member is P (mm) and the outer diameter of the outer metal member is Q (mm), P and Q are as follows: It is preferable to satisfy the relational expression.
5.0 × Q ≧ P ≧ 1.05 × Q

  According to the pressure vessel of the present invention, the metal fitting is present on the outer side opposite to the inner side containing the gas with respect to the synthetic resin liner, and takes the form in which the synthetic resin liner is sandwiched by the screw fastening mechanism. Each of the outer metal members is formed as an integral part, and is at least one place between the outer peripheral surface of the inner metal member and the inner peripheral surface of the synthetic resin liner or between the inner peripheral surface of the outer metal member and the outer peripheral surface of the liner. Since it is a pressure vessel having a sealing mechanism using lip packing, it is possible to suppress the deformation of individual metal fitting members and increase the adhesion with the synthetic resin liner as the whole metal fitting, thereby improving the pressure resistance. The degree of adhesion between the seal mechanism and the liner can be increased to improve the airtightness and, consequently, the pressure resistance. Therefore, it is possible to cope with high pressure resistance characteristics and leakage rules for pressure vessels that are becoming stricter in recent years.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
1 is a partially cutaway perspective view of a pressure vessel T having a gas outlet according to an embodiment of the present invention, FIG. 2 is an enlarged longitudinal sectional view of a cap portion of the pressure vessel T of FIG. 4 is a cross-sectional view of a cap portion of a pressure vessel according to an embodiment different from FIG.

  In FIG. 1, a pressure vessel T penetrates through a liner 1 formed in a cylindrical shape, an FRP outer shell 2 in which a fiber reinforced resin (FRP) layer is laminated on the outer periphery thereof, and an end plate portion. It is comprised with the gas outlet part 3 provided.

  In FIG. 2, 4 is an FRP outer shell in a base portion where fiber reinforced resin layers are laminated, 5 is a synthetic resin liner, and 6 and 7 are sandwiched between synthetic resin liners 5. The outer metal fitting member and the inner metal fitting member are shown, and the outer metal fitting member 6 and the inner metal fitting member 7 are integrally formed by fastening with screws 13.

  Here, the reason why the synthetic resin liner 5 is sandwiched between the metal fittings 6 and 7 is that, apart from the liner member lacking in strength, because the base portion withstands the high pressure of 50 to 70 MPa due to the gas stored in the container. It is necessary to manufacture a metal base metal fitting member, and the leakage of the gas injected into the pressure vessel is minimized despite the fact that it is composed of different materials and parts, such as a synthetic resin liner member and a base metal fitting member. This is because it is necessary to improve the adhesion between the seal mechanism and the liner in order to suppress it.

  Further, here, when the outer and inner metal fittings 6 and 7 are not composed of integral parts (for example, as shown in FIG. 6 of Patent Document 1), the right and left shift of the base metal fitting member is strictly controlled. As a result, the degree of adhesion between the sealing mechanism for minimizing gas leakage and the synthetic resin liner decreases, and gas leakage cannot be kept small. Therefore, the outer and inner metal members 6 and 7 need to be formed of integral parts.

Furthermore, as described in Patent Document 1, when an O-ring or a flat packing is applied to the seal member, the pressure vessel containing a high-pressure gas of 50 to 70 MPa is used when the internal pressure becomes high. Since the deformation allowance is small, the ability to seal high-pressure gas is insufficient, and unless a lip packing with higher sealing performance is applied, the amount of gas leakage from the pressure vessel, for example, the amount of hydrogen leakage is 1.0 cm ³ / hr · It is difficult to keep it below L. 2, reference numerals 8, 9, and 10 respectively denote a support ring, a backup ring, and a lip packing, and the support ring 8, the backup ring 9, and the lip packing 10 constitute a seal mechanism portion. It arrange | positions between an outer peripheral surface and the inner peripheral surface of the synthetic resin liners 5.

  In this case, only one lip packing 10 is shown in the seal mechanism portion of FIG. 2 for the sake of convenience, but a plurality of seal mechanism portions can be continuously (stacked) on one seal mechanism portion, The amount of gas leakage can be further reduced. Normally, it is possible to sufficiently seal the gas only with a sealing mechanism having a lip packing, but from the viewpoint of fail-safe, a sealing mechanism using a squeegee packing such as an O-ring 11 can be used supplementarily. Reference numeral 12 denotes a valve mounting screw, which is a mechanism for mounting a valve (not shown) for taking out the contained gas.

  FIG. 3 is a cross-sectional view of a cap portion of a pressure vessel according to a form different from that of FIG. 2, and shows the space between the outer peripheral surface of the inner metal member 7 and the inner peripheral surface of the synthetic resin liner 5 and This is a configuration having a sealing mechanism between the inner peripheral surface and the outer peripheral surface of the synthetic resin liner 5. The arrangement of such a seal mechanism is not particularly limited. For example, it is effective when the synthetic resin liner 5 is manufactured by blow molding, and the synthetic resin liner 5 is manufactured by multilayer blow molding. In this case, the shape is particularly suitable. Here, reference numeral 14 denotes an inclusion gas barrier layer disposed at the center of the cross section of the synthetic resin liner 5 obtained by multilayer blow molding, and the inclusion gas is substantially sealed by this barrier layer.

  FIG. 4 shows a cross-sectional view of a cap portion of a pressure vessel according to another embodiment different from FIG. 2, and a sealing mechanism is provided between the outer peripheral surface of the inner metal member 7 and the inner peripheral surface of the synthetic resin liner 5. The seal member is positioned in the axial direction of the pressure vessel by the outer metal fitting 6. The FRP outer shell 4 in which the fiber reinforced resin layer is laminated is arranged so as to cover the gas outlet, and it is possible to suppress the circumferential deformation in the gas outlet. The degree of adhesion between the seal mechanism and the synthetic resin liner 5 can be improved, and leakage of the encapsulated gas can be greatly reduced.

Here, the material which comprises the pressure vessel which concerns on this invention is demonstrated in detail.
The outer shell 4 made of FRP in which the fiber reinforced resin layer is laminated is composed of at least one type of reinforcing fiber of glass fiber, carbon fiber, and aramid fiber, and its main material is epoxy resin, unsaturated polyester resin, vinyl ester resin, Phenol resin, polyurethane resin, silicone resin, polyethylene resin, polypropylene resin, polyvinyl chloride resin, ABS resin, polystyrene resin, AS resin, polyamide resin, polyacetal resin, polycarbonate resin, thermoplastic polyester resin, PPS (polyphenylene sulfide) resin, It consists of FRP comprised from at least 1 or more types of resin of a fluororesin, polyetherimide resin, polyetherketone resin, and polyimide resin.

The main material of the synthetic resin liner 5 is polyethylene resin, polypropylene resin, polyvinyl chloride resin, ABS resin, polystyrene resin, AS resin, polyamide resin, polyacetal resin, polycarbonate resin, thermoplastic polyester resin (PET, PBT, PCT etc.), PPS resin, fluororesin, polyetherimide resin, polyetherketone resin, polyimide resin, etc., and may be used alone or in combination of two or more. These thermoplastic resins may be used alone, as a mixture, or as a copolymer. In the case of a mixture, a compatibilizer may be used in combination. Furthermore, brominated flame retardants, silicon-based flame retardants, red phosphorus, and the like may be added as flame retardants. Moreover, you may use ethylene vinyl alcohol (EVOH) etc. which are gas sealing materials in part. When this ethylene vinyl alcohol is applied, it is arranged like the inclusion gas barrier layer 14 in FIG. 3, and the thickness “t-EVOH (mm)” of the EVOH at that time is the pressure vessel outer surface area “Suf ( mm ² ) ”, and the volume inside the container“ Vol (litter) ”should be used so that t-EVOH ÷ (Suf × Vol) is 5 × 10 ⁻⁸ (mm / mm ² · liter) or more. It is.

  The metal fittings 6 and 7 are not particularly limited, but examples of carbon steel include carbon steel pipe for pressure piping, carbon steel pipe for high pressure piping, steel pipe for low temperature piping, carbon steel for machine structure, and manganese steel. Can be exemplified by seamless steel pipes for high-pressure gas containers, manganese steel materials for machine structures, and manganese chrome steel materials. Examples of chromium-molybdenum steel and chrome-molybdenum steel include stainless steel forgings for pressure, stainless steel pipes for piping, stainless steel bars, hot-rolled stainless steel plates and steel strips, cold-rolled stainless steel plates and steel strips. It can be illustrated. Examples of the aluminum alloy include aluminum and aluminum alloy plates, strips, bars, wires, seamless pipes, and forged products. For the liner, the metal material itself may be applied. For carbon steel, annealing and normalizing, for manganese steel, normalizing, quenching and tempering, chromium molybdenum steel and low alloy Quenching and tempering may be applied to steel, solid solution treatment may be applied to stainless steel, and quenching and tempering may be applied to aluminum alloys. Furthermore, for the aluminum alloy, a solution subjected to solution treatment and T6 aging treatment may be applied. In particular, when hydrogen gas is selected as the inclusion gas, it is preferable to apply SUS304, SUS316, and SUS347, which are excellent in resistance to hydrogen embrittlement.

Further, by computer simulation by the finite element method, when the outer diameter of the flange portion of the inner metal fitting member 7 is P and the outer diameter of the outer metal fitting member 6 is Q in the outer metal fitting member 6 and the inner metal fitting member 7, P and Q It is found that it is preferable to satisfy the following relational expression.
5.0 × Q ≧ P ≧ 1.05 × Q

  This is because, in the case of a pressure vessel that receives internal pressure, a force is exerted on the metal fitting part by the internal pressure so as to jump out in the axial direction of the pressure vessel, but this force is supported by the FRP outer shell on which the fiber reinforced resin layer is laminated. That is why. Therefore, if it is not designed to satisfy P ≧ 1.05 × Q, the metal fitting part may jump out in the axial direction of the pressure vessel due to a high internal pressure of 50 to 70 MPa. On the other hand, if P is made too large, the weight of the inner metal fitting member is meaninglessly increased. As a result, the weight of the pressure vessel required to be reduced in weight is increased, which is uneconomical. Therefore, an upper limit is necessary to the extent that the metal fitting part does not protrude in the pressure vessel axial direction due to the high internal pressure, and it is effective to design so that 5.0 × Q ≧ P.

  The material of the lip packing 10 is styrene rubber, chloroprene rubber, IIR, nitrile rubber, natural rubber, silicone rubber, chlorosulfonated polyethylene, fluorine rubber, ethylene propylene rubber, urethane rubber, acrylic rubber, fluorosilicone rubber, polytetrafluoroethylene. Fluorine resins such as hydrogenated nitrile rubber and polytetrafluoroethylene (PTFE) are preferably used, and when the pressure used is high, a composite of reinforcing fibers composed mainly of these may be used. Here, the application is not particularly limited, but for example, when applied to a pressure vessel for storing high-pressure hydrogen used for power generation of a fuel cell vehicle, from the viewpoint of hydrogen resistance, chloroprene rubber, nitrile rubber, IIR, Fluorocarbon resins such as chlorosulfonated polyethylene, fluorine rubber, ethylene propylene rubber, urethane rubber, acrylic rubber, fluorosilicone rubber, polytetrafluoroethylene, hydrogenated nitrile rubber, and polytetrafluoroethylene (PTFE) are preferably applicable. Examples of the lip packing include U packing, V packing, L packing, and J packing.

  The backup ring 9 and the support ring 8 are made of tetrafluoroethylene resin, bakelite, polyamide resin, polyacetal resin or a composite of reinforcing fibers, or mild steel, SUS304, SUS316, SUS347, aluminum alloy, copper, or the like. Preferably used.

  Here, the surface of the synthetic resin liner in contact with the sealing mechanism is preferably 0.01 μm to 25 μm at the maximum height (symbol Ry) defined in JIS B 0601 in order to securely seal the encapsulated gas. When the molecular weight of the encapsulated gas is small, such as hydrogen, it is more preferably 0.01 μm to 6.3 μm.

  The screw 13 that fastens the outer metal member and the inner metal member needs to be designed on the assumption that the pressure of the inclusion gas is as high as 50 to 70 MPa. In general, the static strength of a screw subjected to internal pressure is known to tend to drop significantly as its effective diameter increases, and the design was based on strength calculation based on empirical rules. However, in a situation where a repeated load such as filling and releasing pressure as seen in a pressure vessel is applied, a clear guideline is not recognized. Therefore, in the present invention, a computer simulation using the finite element method and an endurance test by repeated load using an actual screw were performed, and a design guideline for a preferable fastening screw was derived. That is, the screw 13 that fastens the outer metal fitting and the inner metal fitting according to the present invention satisfies L ≧ 0.05 × D when the effective diameter of the screw is D and the screw fastening length is L. I found it necessary to design. At this time, a triangular screw, a square screw, a trapezoidal screw, or a tube screw is preferably used as the screw mode.

  The structure of the cap portion in the pressure vessel according to the present invention is suitable for a pressure vessel that stores a gas such as CNG (compressed natural gas), hydrogen, oxygen, air, etc. under high pressure. It is suitable for a pressure vessel or the like for storing high-pressure hydrogen used in the above.

It is a partially broken perspective view of the pressure vessel concerning one embodiment of the present invention. FIG. 2 is an enlarged longitudinal sectional view of a base part of the pressure vessel of FIG. 1. It is sectional drawing of the nozzle | cap | die part of the pressure vessel which concerns on another embodiment of this invention. It is sectional drawing of the nozzle | cap | die part of the pressure vessel which concerns on another embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure vessel liner 2 FRP outer shell 3 Container center through-hole 4 FRP outer shell laminated with fiber reinforced resin layer 5 Synthetic resin liner 6 Outer metal fitting member 7 Inner metal fitting member 8 Support ring 9 Backup ring 10 Lip packing 11 O-ring 12 Valve mounting screw 13 Screw fastening outer metal member and inner metal member 14 Inner gas barrier layer arranged at the center of the cross section of the synthetic resin liner obtained by multilayer blow molding D Inner and outer Screw effective diameter of the screw mechanism for fastening the metal fitting member L Screw fastening length of the screw mechanism for fastening the inner and outer metal fitting members P Outer diameter of the flange portion of the inner metal fitting member Q Outer diameter of the outer metal fitting member T Pressure vessel

Claims (5)

A pressure vessel in which a base portion installed in a gas outlet portion of a pressure vessel for storing gas has all the following requirements (A), (B), and (C).
(A) Metal fittings provided in the base part are present on the inner side containing gas with respect to the synthetic resin liner and on the outer side relative to the inner side, and the inner and outer metal fitting members are fastened to each other by a screw mechanism. Take the form.
(B) The inner and outer metal members are each composed of an integral part.
(C) A seal mechanism using a lip packing between at least one portion between the outer peripheral surface of the inner metal member and the inner peripheral surface of the liner or between the inner peripheral surface of the outer metal member and the outer peripheral surface of the liner. Having.   The pressure vessel according to claim 1, wherein a liner made of synthetic resin is sandwiched between inner and outer metal fittings. Regarding the screw mechanism for fastening the inner and outer metal fittings, if the effective diameter of the screw is D (mm) and the screw fastening length is L (mm), D and L satisfy the following relational expression. The pressure vessel according to claim 1 or 2, characterized by the above.
L ≧ 0.05 × D In the state where the pressure vessel is projected in the axial direction, when the outer diameter of the flange portion of the inner metal fitting member is P (mm) and the outer diameter of the outer metal fitting member is Q (mm), P and Q are the following relational expressions: The pressure vessel according to any one of claims 1 to 3, wherein the pressure vessel is satisfied.
5.0 × Q ≧ P ≧ 1.05 × Q   The pressure vessel according to any one of claims 1 to 4, which is filled with hydrogen.

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