Low permeability polymeric compound liner-based gas cylinder

Abstract

To provide a gas cylinder assembly having a barrier layer configured to reduce the permeability of gas passing through the gas cylinder assembly.SOLUTION: A gas cylinder assembly has a polymeric compound liner and a low-permeability barrier layer. The polymeric compound liner includes a first end portion, a second end portion, and a central body. The central body comprises an outer surface and an inner surface disposed between the first end portion and the second end portion. The gas cylinder assembly comprises a reinforcement structure wound over the central body. The gas cylinder assembly further comprises a metal foil interposed between the reinforcement structure and the central body. The metal foil is configured to reduce permeation of contents of the polymeric compound liner.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] [Incorporation by reference of priority application] Any application for which a foreign or domestic priority claim is specified in an Application Data Sheet submitted with this application is hereby incorporated by reference under 37 CFR §1.57.

[0002] The present disclosure relates to a gas cylinder assembly having a barrier layer configured to reduce the permeability of gas through the gas cylinder assembly. [Background technology]

[0003] Fuel tanks for compressed natural gas (CNG) can be classified into four types. The first type (Type 1) of CNG tanks are all-metal tanks. All-metal tanks made from aluminum or other metals are inexpensive but heavy and subject to corrosion. The second type (Type 2) of CNG tanks are tanks with a metal liner and a composite hoop or a reinforcing wrapping of the metal hoop. Type 2 tanks are lighter than Type 1 but still subject to corrosion. The third type (Type 3) of CNG tanks are tanks with a metal liner completely wrapped with a composite or fiber resin. Type 3 tanks do not suffer from corrosion but are expensive. The fourth type (Type 4) of CNG tanks are tanks with a polymer liner with a fiber wrapping. Type 4 tanks do not suffer from corrosion, are less expensive than Type 3 tanks and are the lightest for the CNG volume they can store. Thus, Type 4 tanks are more suitable as fuel tanks for heavy vehicles. Type 4 tanks suffer from a higher degree of fuel gas permeability than tanks with metal liners. Summary of the Invention [Problem to be solved by the invention]

[0004] One aspect of the invention provides a gas cylinder having a polymeric liner and a low-permeability or barrier layer. Another aspect of the invention provides a method of manufacturing a gas cylinder assembly having a low-permeability or barrier layer disposed over a polymeric liner. [Means for solving the problem]

[0005] In one embodiment, a gas cylinder for containing compressed gas (gaseous fuel) is provided. The gas cylinder comprises an internal pressure seal comprising a first end portion, a second end portion, and a central body. The central body has a first end coupled to the first end portion of the internal pressure seal and a second end coupled to the second end portion of the internal pressure seal. The central body comprises an outer surface and an inner surface disposed between the first end and the second end. The first end portion, the second end portion, and the central body form a sealed cavity for storing fuel. The inner surface of the central body forms at least a portion of an innermost surface of the internal pressure seal. The central body between the inner surface and the outer surface is a continuous surface of homogenous material. The gas cylinder comprises a stiffening structure disposed, e.g., wrapped, over the central body. Additionally, the gas cylinder comprises a metal foil interposed between the stiffening structure and the central body. The metal foil is configured to reduce permeation of the contents of the internal pressure seal.

[0006] In some embodiments, the metal foil is an aluminum foil having a thickness greater than 0.001 inches. In some embodiments, the metal foil is an aluminum foil having a thickness in the range between 0.0005 inches and 0.05 inches. Metal foils in this thickness range form a barrier to permeation and can be easily applied. Some embodiments are configured to allow for draping a layer, such as a metal foil, over the central body. The metal foil can be a drapeable layer. The metal foil can be draped over and directly onto the central body. The metal foil can be draped over a layer or structure disposed between the draped foil and the central body. As used herein, a drapeable layer is a sheet layer that easily conforms to the surface to which it is applied. Additionally, metal foils in this range do not significantly increase the weight of the gas cylinder in which it is incorporated.

[0007] In some embodiments, the gas cylinder further comprises an adhesive layer interposed between the metal foil and the central body.

[0008] In some embodiments, the metal foil is part of a metal foil structure that includes a polymeric layer. The polymeric layer of the metal foil structure is disposed on a side of the metal foil such that the polymeric layer is interposed between the metal foil and the central body. In other embodiments, the polymeric layer of the metal foil structure is disposed on a side of the metal foil such that the metal foil is interposed between the polymeric layer and the central body. The metal foil may be disposed between two polymeric layers. The polymeric layer may be applied to the metal foil by a coating process. The metal foil may be subjected to a surface treatment. These are examples of processes that can improve durability, provide electrical insulation, or protect the metal foil from corrosion.

[0009] In some embodiments, the central body comprises a cylindrical body. The first end portion can include a hemispherical member coupled to one end of the cylindrical body. The metal foil can be disposed over the cylindrical body.

[0010] In some embodiments, the metal foil is disposed over the cylindrical body and has circumferential ends spaced apart from the hemispherical members. In some examples, the metal foil is part of a permeation barrier layer having one or more longitudinal ends longitudinally disposed between the hemispherical members of the internal pressure seal, e.g., spaced apart from the hemispherical members of the internal pressure seal. In some examples, the metal foil is part of a permeation barrier layer disposed only between the first end and the second end of the central body.

[0011] In some embodiments, the metal foil is disposed in a laminate structure and wrapped around the central body, hi some embodiments, the metal foil is wrapped circumferentially around the central body.

[0012] In another aspect of the disclosure, a high pressure vessel assembly includes a polymeric inner liner. The polymeric inner liner has a central portion and a domed end portion on each end of the central portion. The central portion has an inner surface, an outer surface, and a wall disposed between the inner surface and the outer surface. The high pressure vessel assembly further includes a permeation barrier layer disposed over the central portion and, in some examples, on the domed end portion on at least one end of the central portion. In some examples, the high pressure vessel assembly includes a permeation barrier layer disposed over the central portion and not over the domed end portion on one or more ends of the central portion. Additionally, the high pressure vessel assembly includes a stiffening layer comprising a flexible ribbon material disposed over the permeation barrier.

[0013] In some embodiments, the permeation barrier layer comprises a metal layer disposed over the outer surface of the central portion and on the outer surface of each domed end portion.

[0014] In some embodiments, the permeation barrier layer comprises a metal sheet, e.g., a film, disposed over the outer surface of the central portion with the longitudinal edges overlapping, which in some embodiments may be disposed on the outer surface of each domed end portion.

[0015] In some embodiments, the permeation barrier layer comprises a polymeric layer comprising EVOH disposed over the exterior surface of the central portion. A layer comprising EVOH may be disposed on the exterior surface of each domed end portion in some embodiments.

[0016] In some embodiments, the permeation barrier layer comprises a first component disposed over the central portion and a second component disposed over an exterior surface of one or each of the domed end portions, the second component being different from the first component.

[0017] In some embodiments, the permeation barrier layer comprises an elongated strip disposed over a central portion of the polymeric inner liner. The strip has a longitudinal axis aligned with the longitudinal axis of the permeation barrier layer. The strip may have a longitudinal axis disposed circumferentially around the permeation barrier layer. The strip may comprise a metal layer and, optionally, one or more polymer layers on one or more sides of the metal layer. An adhesive may be provided on one or more sides of the strip before or after the strip is applied to the liner or internal pressure seal.

[0018] In some embodiments, the permeation barrier layer comprises a plurality of elongated strips in contact with the exterior surface of a polymeric liner or pressure seal.

[0019] In another embodiment, a method for manufacturing a gas cylinder is provided that includes the steps of: (1) providing a polymeric cylinder having an inner circumferential surface and an outer circumferential surface, the inner circumferential surface constituting at least a portion of an innermost surface of the gas cylinder, (2) forming a permeation barrier layer over the outer circumferential surface, the permeation barrier layer having a thickness sufficient to limit permeation, such as greater than 0.0002 inches, (3) providing a first dome-shaped member having a first opening and a second dome-shaped member having a second opening, (4) securing the first dome-shaped member to a first end of the polymeric cylinder and securing the second dome-shaped member to a second end of the polymeric cylinder to provide a low permeation container having a central portion with an outer surface formed by the permeation barrier layer, and (5) wrapping one or more stiffener strips over the permeation barrier layer to form an outer shell of the gas cylinder.

[0020] In some embodiments, forming the permeation barrier layer includes wrapping one or more metal foils over the outer circumferential surface. The metal foils have a thickness in the range between 0.0005 inches and 0.05 inches. The metal foils may be wrapped circumferentially over the outer circumferential surface.

[0021] In some embodiments, forming the permeation barrier layer comprises depositing a metal layer by a vapor deposition process, hi certain embodiments, forming the permeation barrier layer comprises applying a metallized film strip longitudinally over the exterior surface of the polymeric cylinder.

[0022] In some embodiments, the permeation barrier layer is a first permeation barrier layer, and the method of manufacturing the gas cylinder further includes disposing a second permeation barrier layer over the first dome portion and / or the second dome portion. The second permeation barrier layer can have a different composition than the first permeation barrier layer.

[0023] In some embodiments, a gas cylinder assembly includes a polymeric inner liner having an inner surface and an outer surface, and a metal foil structure disposed over the inner or outer surface of the liner. The gas cylinder assembly further includes a stiffening layer including a flexible ribbon material disposed to be wrapped over the polymeric inner liner and the metal foil structure. The stiffening layer including the flexible ribbon material may be disposed directly over the metal foil structure in some embodiments. In certain embodiments, the polymeric inner liner includes a single, unitary layer of material disposed between the inner and outer surfaces of the liner.

[0024] The features of the present invention can be better understood from the following detailed description in conjunction with the accompanying schematic drawings, which are for illustrative purposes only and which comprise the following figures: [Additional note 1] 1. A gas cylinder for containing compressed gas, comprising: A first end portion; A second end portion; a central body having a first end connected to the first end portion and a second end connected to the second end portion, the central body having an outer surface and an inner surface disposed between the first end and the second end; An internal pressure sealing body comprising: the first end portion, the second end portion and the central body forming a sealed cavity for storing the compressed gas, the inner surface of the central body forming at least a portion of an innermost surface of the internal pressure seal; the central body disposed between the inner surface and the outer surface being a continuous surface of a homogenous material; a stiffening structure disposed over the central body; a metal foil interposed between the stiffening structure and the central body, the metal foil being configured to reduce permeation of the contents of the internal pressure seal; A gas cylinder comprising: [Additional note 2] 2. The gas cylinder according to claim 1, wherein the metal foil is an aluminum foil having a thickness of 0.0005 inches to 0.05 inches. [Additional note 3] 2. The gas cylinder of claim 1, wherein the gas cylinder comprises an adhesive layer interposed between the metal foil and the central body. [Additional note 4] 2. The gas cylinder of claim 1, wherein the metal foil comprises a portion of a metal foil structure comprising a polymeric layer, the polymeric layer of the metal foil structure being disposed on a side of the metal foil such that the polymeric layer is interposed between the metal foil and the central body. [Additional note 5] the central body comprises a cylindrical body; the first end portion comprises a hemispherical member coupled to one end of the cylindrical body; 2. The gas cylinder of claim 1, wherein the metal foil is arranged to cover the cylindrical body. [Additional note 6] the central body comprises a cylindrical body; the first end portion comprises a hemispherical member coupled to one end of the cylindrical body; 2. The gas cylinder of claim 1, wherein the metal foil has a circumferential end spaced apart from the hemispherical member. [Additional note 7] 2. The gas cylinder of claim 1, wherein the metal foil is arranged in a laminate structure and wrapped around the central body. [Additional note 8] 8. The gas cylinder of claim 7, wherein the metal foil is wrapped circumferentially around the central body. [Additional note 9] 1. A high pressure vessel assembly comprising: a polymeric inner liner having a central portion and dome-shaped end portions disposed at each end of the central portion, the central portion having an inner surface, an outer surface, and a wall portion disposed between the inner surface and the outer surface; a permeation barrier layer disposed on the domed end portion that is disposed at one or more ends of the central portion so as to cover the central portion; a stiffening layer comprising a flexible ribbon material disposed over the permeation barrier layer; A high pressure vessel assembly comprising: [Additional Note 10] 10. The high pressure vessel assembly of claim 9, wherein the permeation barrier layer comprises a metal layer disposed on an outer surface of each of the domed end portions so as to cover the outer surface of the central portion. [Additional Note 11] 10. The high pressure vessel assembly of claim 9, wherein the permeation barrier layer comprises a metal film disposed on the outer surface of each of the domed end portions so as to cover the outer surface of the central portion with the longitudinal edges overlapping. [Additional Note 12] 10. The high pressure vessel assembly of claim 9, wherein the permeation barrier layer comprises a polymer layer comprising EVOH disposed on the outer surface of each of the domed end portions so as to cover the outer surface of the central portion. [Additional Note 13] the permeation barrier layer comprises a first component disposed over the central portion and a second component disposed over an exterior surface of each of the domed end portions; 10. The high pressure vessel assembly of claim 9, wherein the second component is different from the first component. [Additional Note 14] 10. The high pressure vessel assembly of claim 9, wherein the permeation barrier layer comprises an elongated strip disposed over the central portion of the polymeric inner liner. [Additional Note 15] 10. The high pressure vessel assembly of claim 9, wherein the permeation barrier layer comprises a plurality of elongated strips in contact with the outer surface of the polymeric inner liner. [Additional Note 16] 1. A method for manufacturing a gas cylinder for containing compressed gas, comprising the steps of: providing a polymeric cylinder extending between a first end and a second end, the polymeric cylinder having an inner circumferential surface and an outer circumferential surface, the inner circumferential surface forming at least a portion of an innermost surface of the gas cylinder; forming a permeation barrier layer covering the outer periphery, the permeation barrier layer having a thickness greater than 0.0002 inches; Providing a first dome-shaped member having a first opening and a second dome-shaped member having a second opening; securing the first dome-shaped member to the first end of the polymeric cylinder and the second dome-shaped member to the second end of the polymeric cylinder to form a low-permeability container having a central portion having an exterior surface formed by the permeation barrier layer; wrapping one or more stiffener strips over the permeation barrier layer to form an outer shell of the gas cylinder; The method comprises: [Additional Note 17] 17. The method of claim 16, wherein the step of forming the permeation barrier layer comprises wrapping one or more metal foils around the outer periphery, the metal foils having a thickness between 0.0005 inches and 0.05 inches. [Additional Note 18] 17. The method of claim 16, wherein the step of forming the permeation barrier layer includes depositing a metal layer by a vapor deposition process. [Additional Note 19] 17. The method of claim 16, wherein the step of forming the permeation barrier layer comprises applying a metallized film strip longitudinally over the exterior surface of the polymeric cylinder. [Additional Note 20] the permeation barrier layer is a first permeation barrier layer; the method comprising disposing a second permeation barrier layer on the first dome portion and / or the second dome portion; 17. The method of claim 16, wherein the first permeation barrier layer and the second permeation barrier layer have different compositions. [Brief description of the drawings]

[0025] [Figure 1] 1 illustrates a vehicle having a gas cylinder assembly integrated into a side-mounted fuel system according to one embodiment. [Diagram 2] FIG. 1 is a side view of a gas cylinder assembly according to one embodiment. [Diagram 3] FIG. 3 is a cross-sectional view of the gas cylinder assembly taken along section 3-3 of FIG. 2. [Figure 4] 4 is an enlarged view of detail 4-4 of FIG. 3, showing the structure of the central portion of the tank gas cylinder assembly of FIG. 2. [Diagram 5] 3A is an enlarged view of detail 5-5 of FIG. 3, showing the structure of the end portion of the tank gas cylinder assembly of FIG. 2. [Figure 6] FIG. 2 illustrates an internal pressure seal of a gas cylinder assembly according to one embodiment. [Figure 7] 7 is a cross-sectional view of the internal pressure seal taken along section 7-7 of FIG. 6. [Figure 8] 7 is a cross-sectional view of an assembly in which a barrier layer is disposed over the internal pressure seal of FIG. 6. [Figure 9] FIG. 9 is an enlarged view of detail 9 of the assembly of FIG. 8. [Figure 10] FIG. 7 illustrates one embodiment of a gas cylinder assembly having a barrier layer material in the form of a strip circumferentially wrapped or wound around the internal pressure sealing body of FIG. 6, and further illustrates the process of wrapping or winding the strip such that the longitudinal axis of the strip is positioned approximately transverse to the longitudinal direction of the internal pressure sealing body. [Figure 11] FIG. 5 is an enlarged partial cross-sectional view similar to FIG. 4 of a central portion of a gas cylinder, further illustrating multiple layers of a permeation barrier structure according to one embodiment. [Figure 12]7 illustrates a process for installing a strip of barrier layer material over the internal pressure seal of Figure 6. The longitudinal axis of the strip is aligned with the longitudinal direction of the internal pressure seal according to one embodiment. [Figure 13] FIG. 13 illustrates a gas cylinder assembly having a permeation barrier formed of multiple strips of barrier layer material, such as by repeating the process illustrated in connection with FIG. 12. [Figure 14] FIG. 7 illustrates an embodiment of a gas cylinder assembly in which a sheet, such as a barrier material film, is wrapped over a central portion of the internal pressure seal of FIG. [Figure 15] 15 is a cross-sectional view taken along section 15-15 shown in FIG. 14. [Figure 16] FIG. 16 is an enlarged view of detail 16 of FIG. [Figure 17] FIG. 7 illustrates a gas cylinder assembly in which a barrier layer having the same configuration covers a central portion and one or more end portions of the internal pressure seal of FIG. 6, according to one embodiment. [Figure 18] 7A-7C illustrate a gas cylinder assembly in which differently configured barrier layers cover one or both of the central and end portions of the internal pressure seal of FIG. 6, according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] It will be understood that, although the present description presents specific details of various embodiments, they are merely illustrative and should not be construed as limiting. Moreover, various applications of such embodiments and modifications thereof that may occur to those skilled in the art are encompassed by the general concepts described herein. All features described herein and all combinations of two or more of such features are included within the scope of the present invention, provided that the features included in such combinations are not mutually inconsistent.

[0027] This application discloses a novel gas cylinder assembly and a method of manufacturing the gas cylinder assembly. As used herein, "cylinder" is a term that includes storage tanks, high pressure vessels, and other vessels that can be used for gas storage and are not necessarily limited to a particular shape, such as strictly cylindrical and / or having a constant or unchanging circular cross-sectional shape. FIG. 1 shows a fuel system 90 with a gas cylinder assembly 100 installed on a vehicle 10 according to one embodiment. The gas cylinder assembly 100 is in fluid communication with and supplies fuel to the internal combustion engine or any other power generation system of the vehicle 10. In various embodiments, the vehicle 10 may be a large vehicle such as an automobile, a wagon, a van, a bus, a multi-passenger vehicle, a truck, a tractor trailer truck, a garbage truck, or any other vehicle. In various embodiments, the gas cylinder assembly 100 is configured for use in marine vessels, aircraft, and mobile or stationary fuel stations. The illustrated fuel system 90 is a side-mounted system with one gas cylinder (fuel tank) disposed within a housing. The gas cylinder assembly 100 disclosed herein may be used in a fuel system having two or more gas cylinder assemblies that may be configured to be positioned behind the driver's seat of a vehicle, that may be configured to be positioned on a roof, and / or that may be mounted to the tailgate of a vehicle.

[0028] [Gas cylinder assembly structure] 2 and 3 show that the gas cylinder assembly 100 comprises a central portion 200 and two end portions 210, 220. The central portion 200 may have a cylindrical tube shape. In other embodiments, the central portion has a shape other than a cylinder. In some embodiments, each of the two end portions 210, 220 comprises a dome-like structure 232, 233 as shown in FIG. 2. In certain embodiments, the two end portions are symmetrical to each other. The dome-like structure 232, 233 may have a generally hemispherical shape at least at its end portions. In certain embodiments, the two end portions 210, 220 have different shapes such that the gas cylinder assembly 100 has an asymmetric shape.

[0029] In some embodiments, the gas cylinder assembly 100 includes at least one neck 142, 143 (e.g., a longitudinal protrusion of a boss) that forms an inlet and / or an outlet for an interior volume of the gas cylinder assembly 100. In some embodiments, the gas cylinder assembly 100 includes necks 142, 143 formed on both end portions 210, 220. In certain embodiments, a neck may be formed on only one of the two end portions 210, 220. In some embodiments, the necks 142, 143 may be part of a metal structure, sometimes referred to as a boss, that is formed through a first end portion 124 of the internal pressure seal 120, sometimes referred to as an inner liner assembly or simply a liner of the gas cylinder assembly 100. The internal pressure seal 120 is described below with reference to FIGS. 6 and 7.

[0030] The necks 142, 143 may be fabricated from a metal structure, but may also be fabricated from one or more other materials. In certain embodiments, the necks 142, 143 are formed using one or more materials not used for the internal pressure seal 120. In certain embodiments, the neck 142 is fabricated from the same material as the internal pressure seal 120.

[0031] 3 and 4 show that the gas cylinder assembly 100 can have multiple layers each performing a different function. As discussed above and in more detail below, the internal pressure seal 120, which can itself be an assembly, primarily provides an internal space 300 (sealed cavity) for containing fuel. A stiffening structure 110 (e.g., an outer shell) is disposed over the internal pressure seal 120 to provide additional strength to the gas cylinder assembly 100. The strength provided by the stiffening structure 110 supports the gas cylinder assembly 100 when the tank assembly is pressurized (as indicated by the arrow in FIG. 4). FIG. 4 shows that the central portion 200 of the tank gas cylinder assembly 100 can have additional layered structures.

[0032] 4, the central body 126 of the internal pressure seal 120 is the innermost layer of the layered structure. The inner surface 129 of the central body 126 defines at least a portion of the interior space 300 of the gas cylinder assembly 100.

[0033] In some embodiments, the central body 126 and the domed end portions (domed structures) 162, 163 of the internal pressure seal 120 are constructed using one or more polymeric materials. In certain embodiments, the one or more polymeric materials may be selected from nylon, high density polyethylene (HDPE), polyvinyl chloride (PVC), ethylene propylene diene terpolymer (EDPM), polyethylene terephthalate (PET), and polyketone (POK). Hereinafter, a process for manufacturing the internal pressure seal (inner liner) 120 will be described with reference to Figures 6 and 7.

[0034] In some embodiments, within the region shown in FIG. 4, the central body 126 of the internal pressure seal 120 has a thickness of 0.01, 0.02, 0.03, 0.05, 0.08, 0.09, 0.1, 0.12, 0.13, 0.15, 0.18, 0.19, 0.2, 0.21, 0.23, 0.25, 0.28, 0.29, 0.30 inches. In several embodiments, the central body 126 has a thickness within a range defined by any two numbers selected from the numbers recited in the preceding sentence such that the central body 126 has sufficient stiffness for further processing (e.g., to support compressive loads applied in the wrapping of the carbon fiber material over the body 126). In other embodiments, the central body 126 has a thickness greater than 0.30 inches. In other embodiments, the central body 126 has a thickness less than 0.01 inches. In some embodiments, the central body 126 has a thickness of about 0.10 inches or greater when made from nylon. In some embodiments, the central body 126 has a thickness of about 0.18 inches or greater when made from HDPE.

[0035] A permeation barrier layer 134 is disposed over the central body 126 of the internal pressure seal 120 to further reduce fuel permeation from the interior space 300 through the central portion 200 of the gas cylinder assembly 100. In embodiments, as discussed further below, portions of the gas cylinder assembly 100 other than the central portion 200 can also have the same or similar layered structures. For example, the end portions 210, 220 can have at least a portion of a similar layered structure.

[0036] 3 and 4 show that in some embodiments, a permeation barrier layer 134 is interposed between the internal pressure seal 120 and the stiffening structure 110. The permeation barrier layer 134 may be immediately adjacent to and in contact with the central body 126 (e.g., its outer surface 127) of the internal pressure seal 120. In other embodiments, one or more additional layers may be interposed between the permeation barrier layer 134 and the central body 126, as discussed further below. In certain embodiments, the permeation barrier layer may be disposed at or on the inner surface 129 of the central body 126.

[0037] In certain embodiments, the permeation barrier layer 134 is immediately adjacent to and in contact with the outer stiffening structure 110. The permeation barrier layer 134 can be immediately adjacent to and in contact with both the outer surface 127 of the central body 126 and the inner surface of the outer stiffening structure 110. In other embodiments, one or more additional layers can be interposed between the permeation barrier layer 134 and the outer stiffening structure 110.

[0038] In some embodiments, the permeation barrier layer 134 includes one or more low permeability barrier materials. In certain embodiments, the one or more low permeability barrier materials may be selected from metals (e.g., aluminum, tungsten, stainless steel), alloys, metal compounds (e.g., aluminum oxide, titanium), polyvinylidene chloride (PVDC), ethylene vinyl alcohol (EVOH), polyamide, and polyethylene terephthalate (PET). In certain embodiments, the foil may be made of any metal that can be configured to form a homogenous continuous metal layer that is impermeable to gas. Also, more preferred materials are lightweight and low cost. Aluminum foil is a preferred example. A process for disposing the permeation barrier layer 134 over the internal pressure seal 120 is described below in connection with FIGS. 8-18.

[0039] In some embodiments, within the region shown in FIG. 4, the permeation barrier layer 134 has a thickness of 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.005, 0.009, 0.01, 0.02, 0.05, 0.09, 0.1 inches. In some embodiments, the permeation barrier layer 134 has a thickness within a range defined by any two numbers selected from the numbers recited in the preceding sentence. In other embodiments, the permeation barrier layer 134 has a thickness greater than 0.1 inches. In other embodiments, the permeation barrier layer 134 has a thickness less than 0.0001 inches.

[0040] In some embodiments, within the region shown in FIG. 4, the permeation barrier layer 134 is comprised of a metal foil layer having a thickness of 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.005, 0.009, 0.01, 0.02, 0.05, 0.09, 0.1 inches. In some embodiments, the permeation barrier layer 134 has a thickness within a range defined by any two numbers selected from the numbers recited in the preceding sentence. In other embodiments, the permeation barrier layer 134 has a thickness greater than 0.1 inches. In other embodiments, the permeation barrier layer 134 has a thickness less than 0.0001 inches. The permeation barrier layer 134 may be configured to allow for draping over a structure disposed therein. The permeation barrier layer can be a drapeable metal foil. The permeation barrier layer 134 can be draped over and directly onto the central body 126. If configured as a metal foil, the barrier layer 134 can be draped such that the metal surface is directly on the central body 126 or directly on a structure disposed between the draped foil and the central body. As used herein, a drapeable layer is a sheet layer that easily conforms to the surface to which it is applied.

[0041] In some embodiments, the metal foil layer, if it is less than 0.001 inches thick, may be susceptible to the formation of small pinholes during its manufacturing or transfer process. Pinholes in the metal foil layer may increase the permeability to fuel gas. Thus, in some embodiments, an additional coating may be applied to fill pinholes in the metal foil in forming the permeation barrier layer 134.

[0042] In some embodiments, within the region shown in FIG. 4, the stiffening structure 110 has a thickness of 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.5, or 2.0 inches. In some embodiments, the stiffening structure 110 has a thickness within a range defined by any two numbers selected from the numbers recited in the preceding sentence. In other embodiments, the stiffening structure 110 has a thickness greater than 2.0 inches. In other embodiments, the stiffening structure 110 has a thickness less than 0.05 inches.

[0043] In some embodiments, the permeation barrier layer 134 has a thickness that is substantially less than the central body 126 in the region shown in FIG. 4. If the permeation barrier layer 134 is made of a metal layer and has a higher density than the central body 126, having a thinner permeation barrier may be advantageous to reduce the overall weight of the gas cylinder assembly. In some embodiments, the permeation barrier 134 has a thickness that is 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, or 30% of the thickness of the central body 126. In some embodiments, the permeation barrier layer 134 has a thickness expressed as a percentage of the thickness of the central body 126 within a range defined by any two numbers selected from the numerical values ​​recited in the preceding sentence. In other embodiments, the permeation barrier layer 134 has a thickness that is greater than 30% of the thickness of the central body 126. In other embodiments, the permeation barrier layer 134 has a thickness that is less than 0.1% of the thickness of the central body 126 .

[0044] In some embodiments, the permeation barrier layer 134 does not result in a significant increase in the overall weight of the gas cylinder assembly 100, thereby allowing the gas cylinder assembly 100 to have better (lower) permeability than a Type 4 CNG tank while maintaining a weight per unit volume comparable to a Type 4 CNG tank (e.g., 0.3-0.45 kg / L).

[0045] In some embodiments, the gas cylinder assembly 100 has a weight per unit volume of 0.1, 0.2, 0.25, 0.3, 0.35, 0.4, or 0.45 kg / L. In some embodiments, the gas cylinder assembly 100 has a weight per unit volume within a range defined by any two numbers selected from the numbers recited in the preceding sentence. In some embodiments, the gas cylinder assembly 100 has a weight per unit volume of less than 0.1 kg / L. In other embodiments, the gas cylinder assembly 100 has a weight per unit volume of more than 0.45 kg / L.

[0046] In some embodiments, the stiffening structure 110 is constructed using composite materials. In certain embodiments, the stiffening structure 110 is made of layers of fiber-reinforced composite material (e.g., carbon fiber reinforced polymer resin). In certain embodiments, materials other than the composite materials described above may be used to form the stiffening structure 110.

[0047] 5 shows that the end portion 210 of the tank gas cylinder assembly 100 may have a layered structure. The first end portion 124 of the internal pressure seal 120 is provided at the end portion 210 of the gas cylinder assembly 100. The first end portion 124 of the internal pressure seal 120 comprises an assembly of a first domed end portion 162 and a first boss 144 with a neck portion 142. The first domed end portion 162 and the first boss 144 in combination form the innermost portion of the end portion 210 and define at least a portion of the interior space 300 of the tank gas cylinder assembly 100.

[0048] 2-5 show that in some embodiments, the permeation barrier layer 134 is disposed within the first end portion 210 over the entire first domed end portion 162 up to, but not including, the boss 144. In some embodiments, the permeation barrier 134 extends beyond the interface between the inner liner 124 and the boss 144, and may also extend over the boss 144. In certain embodiments, the permeation barrier 134 does not extend beyond the interface 150 between the inner liner 124 and the boss 144. In other embodiments, the permeation barrier 134 extends beyond the interface 150 to cover at least a portion of the boss 144.

[0049] [Method of manufacturing a gas cylinder assembly] In some embodiments, a method of manufacturing a gas cylinder assembly 100 includes (1) forming an internal pressure seal 120 of FIG. 6; (2) forming a permeation barrier layer 134 over at least a portion of the internal pressure seal 120 or on at least a portion of an inner surface of the internal pressure seal 120 to form an intermediate assembly 130 of FIG. 8; and (3) subsequently forming a stiffening structure 110 over the permeation barrier layer 134.

[0050] In some embodiments, the central body 126 of the internal pressure seal 120 may be manufactured by forming a cylindrical tube, such as by rolling a polymeric sheet into a cylindrical tube, in other embodiments, the central body 126 may be manufactured using other processes including injection molding and extrusion.

[0051] In some embodiments, the first end portion 124 of the internal pressure seal 120 may be prepared by (a) forming a first dome-shaped member 162 of a polymeric material using an injection molding process, (b) forming the first dome-shaped end portion 162 by forming a central hole through the first dome-shaped member, and (c) bonding the boss 144 to the first dome-shaped end portion 162 through the central hole. The second dome-shaped member 163 and the second end portion 125 may be prepared using the same or a similar layered forming process.

[0052] In certain embodiments, forming the first dome-shaped member and forming the central hole may be performed simultaneously in one injection molding process. In some embodiments, processes other than injection molding may be utilized to manufacture the first dome-shaped member 162. In some embodiments, the first dome-shaped member 162 is a hemispherical member with a central opening therethrough.

[0053] After the central body 126 and the end portions 124, 125 are manufactured, a first end 181 of the central body 126 is bonded to the first end portion 124 and a second end 183 of the central body 126 is bonded to the second end portion 125 to form the internal pressure seal 120. In certain embodiments, a welding process is utilized to bond the central body 126 and the end portions 124, 125, which may leave a weld line 128 along the interface between the central body 126 and the two end portions 124, 125, as shown in Figures 6 and 7. In some embodiments, the central body 126 and the end portions 124, 125 are secured to one another using an adhesive material.

[0054] In some embodiments, after the internal pressure seal 120 is prepared, a permeation barrier layer 134 is formed over the internal pressure seal 120 to form the intermediate assembly 130. In the embodiment of Figures 8 and 9, the permeation barrier layer 134 covers the central body 126 and at least a portion of the end portions 124, 125. For example, the permeation barrier layer 134 covers the entire central body 126 and also covers the domed end portion 162 up to and / or including the boss 144.

[0055] In some embodiments, the permeation barrier layer 134 is formed by applying one or more strips of barrier material onto the outer surface of the internal pressure seal 120. In other embodiments, the barrier material is painted or sprayed onto the outer surface of the internal pressure seal 120 (metallization process). In some embodiments, the barrier material is deposited using a vapor deposition process. In certain embodiments, wrapping a metal foil over the internal pressure seal 120 is preferred over a metallization process. Without being bound to any particular theory, it is believed that the continuous extension of the metal in the metal foil may provide better (lower) permeability compared to a coating of thickness or volume formed by a metallization process. In certain embodiments, processes other than those discussed above may be used to form the permeation barrier layer. Various processes for forming the permeation barrier layer are described in more detail below.

[0056] FIG. 10 illustrates that in one embodiment, one or more barrier material strips (e.g., tapes, ribbons) 134-1 are wrapped around and around the circumferential direction of the internal pressure seal 120 to form a permeation barrier layer of the intermediate assembly 130-1. The strips may be applied generally transverse to the longitudinal direction of the seal 120. In some embodiments, two adjacent wrapped strips of barrier material strip 134-1 overlap each other such that one portion of the permeation barrier layer 134-1 is thicker than another portion. In some embodiments, the wrapped strip of barrier material strip 134-1 extends over, for example beyond, the weld line 128 along the longitudinal direction of the intermediate assembly 130-1 such that the barrier material strip 134-1 is disposed over the weld line 128. The barrier material strip 134-1 may also extend beyond the domed end portion 162 of the internal pressure seal 120. In certain embodiments, the wrapped strip of barrier material strip 134-1 remains between the weld lines 128 and the domed end portion 162 is not covered by the barrier material strip 134-1.

[0057] FIG. 11 illustrates that in some embodiments, the permeation barrier layer 134-2 interposed between the sealing body 120 and the structure 110 is a multi-layer member. In some embodiments, the permeation barrier layer 134-2 comprises a metal foil 182, a first polymer layer 181, and a second polymer layer 183. In addition, the permeation barrier layer 134-2 can comprise an adhesive layer 184 in some variations. In some embodiments, the permeation barrier layer 134-2 does not comprise at least one of the first polymer layer 181 and the second polymer layer 183. In some embodiments, the permeation barrier layer 134-2 does not comprise the adhesive layer 184. In certain embodiments, the permeation barrier layer 134-2 excludes the metal foil 182 and comprises at least one of the polymer layers 181, 183. In certain embodiments, the metal foil 182 without any additional layers can be wrapped directly over the outer surface 127 of the internal pressure sealing body 120 to form a permeation barrier. The stiffening structure 110 may be applied directly onto the permeation barrier layer 134-2, for example, directly onto one of the polymer layer or adhesive layer, or directly onto the metal foil layer. The stiffening structure 110 can be applied directly onto the metal foil 182 of the permeation barrier layer 134-2 of the variant, for example, for variants in which the first polymer layer 181 is not present. In some variants, there is direct contact between the metal foil 182 and the stiffening structure 110. In some variants, there is direct contact between the metal foil 182 and the internal pressure sealing body 120. In some variants, there is direct contact between the internal pressure sealing body 120 and the metal foil 182 and / or between the stiffening structure 110 and the metal foil 182. In some embodiments, the first polymer layer 181 is a polymer layer comprising ethylene vinyl alcohol (EVOH). In some embodiments, the second polymer layer 183 is a polymer layer comprising ethylene vinyl alcohol (EVOH). In certain embodiments, the permeation barrier layer does not comprise a metal foil layer but rather comprises a layer of low permeability ethylene vinyl alcohol (EVOH).

[0058] 12 and 13, one or more barrier material strips (e.g., tapes, ribbons) 134-3 are disposed over the seal 120 along its length to form a permeation barrier layer 134-4, thereby forming the intermediate assembly 130-2. In some embodiments, the permeation barrier layer 134-4 includes a barrier material strip 134-3 that at least partially overlaps another barrier material strip, as shown in FIG 13. In some embodiments, the overlap of two adjacent strips causes the permeation barrier layer 134-4 to have portions that are thicker than other portions.

[0059] 14-16, one or more metal films are wrapped over the central body 126 to form the permeation barrier layer 134-5 to form the intermediate assembly 130-3. In some embodiments, as shown in FIGS. 15 and 16, the permeation barrier layer 134-5 is disposed longitudinally over the central body 126 between the weld lines 128 but not over the domed end portions 162, 163, such that the permeation barrier layer 134-5 has circumferential ends spaced apart from the domed end portions 162, 163, e.g., between the weld lines 128 where the domed end portions 162, 163 are bonded to the central body 126. In some embodiments, the permeation barrier layer 134-5 extends longitudinally along the intermediate assembly 130-3 beyond the weld lines 128 to cover the longitudinal ends 181, 183 of the central body 126 and to cover at least a portion of the domed end portions 162, 163.

[0060] 17 illustrates a further embodiment in which a permeation barrier layer 134-6 is formed over the central body 126 and also over the domed end portions 162, 163 to form an intermediate assembly 130-4. In some embodiments, when the permeation barrier 134-6 is formed by a single process or by repeating the same process (e.g., the process of FIG. 12, i.e., by repeating the application of strips as shown in FIG. 12), the permeation barrier layer 134-6 maintains the same configuration over the central portion 126 and the domed end portions 162, 163 of the internal pressure seal 120.

[0061] 18, a permeation barrier layer 136 is disposed over the internal pressure seal 120 to form an intermediate assembly 130-5. The permeation barrier layer 136 includes a first portion 134-7 disposed over the central body 126 of the internal pressure seal 120 and a second portion 134-8 disposed over the domed end portions 162, 163 of the internal pressure seal 120.

[0062] In some embodiments, the first portion 134-7 is formed using a first process and the second portion 134-8 is formed using a second process that is different from the first process, thereby disposing the permeation barrier layer 136 over the curved surface of the domed end portion 162. In some embodiments, the first portion 134-7 and the second portion 134-8 may be formed by the same or similar processes, but one may be thicker. For example, the first portion 134-7 may be thicker than the second portion 134-8. Or, the second portion 134-8 may be thicker than the first portion 134-7.

[0063] In some embodiments, the first portion 134-7 and the second portion 134-8 may each have a different configuration (e.g., mechanical structure, chemical composition, etc.). In some embodiments, when a barrier material strip is applied over the central body 126 and the domed end portions 162, 163 of the internal pressure seal 120 to form the second portion 134-8 (using the process shown in Figures 12 and 13), and then an additional barrier material strip is wrapped over the central body 126 to form the first portion 134-7 (using the process shown in Figure 10), the permeation barrier layer 136 is thicker over the central body 126 than over the domed end portion 162.

[0064] After the permeation barrier layer is formed over the internal pressure seal 120 and the intermediate assembly 130, 130-1, 130-2, 130-3, 130-4, or 130-5 is prepared, the stiffening structure 110 may be formed over the permeation barrier layer. In some embodiments, one or more carbon composite strips (or sheets) are wrapped over the intermediate assembly to form the stiffening structure 110. In some embodiments, a polymeric resin is painted or sprayed onto the carbon fiber reinforcement after disposing the carbon fiber reinforcement over the permeation barrier layer, thereby forming the stiffening structure 110. In certain embodiments, a process is performed to cure the composite (or resin) disposed over the permeation barrier layer to complete the stiffening structure 110.

[0065] Although specific embodiments of the present invention have been described, these embodiments are presented only as examples and are not intended to limit the scope of the present disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions, and modifications can be made in the systems and methods described herein without departing from the spirit of the present disclosure. The appended claims and their equivalents are intended to cover such forms or modifications as fall within the scope and spirit of the present disclosure. Thus, the scope of the present invention is defined solely by reference to the appended claims.

[0066] A feature, material, property, or group described in combination with a particular aspect, embodiment, or example, should be understood as applicable to all other aspects, embodiments, or examples described in this section or elsewhere in this specification, unless incompatible. All features disclosed in this specification (including any accompanying claims, abstract, and drawings) and / or all steps of any method or process so disclosed may be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive. The scope of protection is not limited to the details of any of the foregoing embodiments. The scope of protection extends to any novel one or any novel combination of features disclosed in this specification (including any accompanying claims, abstract, and drawings) or to any novel one or any novel combination of steps of any method or process so disclosed.

[0067] Moreover, certain features that are described within the disclosure in the context of separate implementations can also be combined and implemented into a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented into multiple implementations separately or in any suitable subcombination. Furthermore, although some features may be described above as operating in a particular combination, in some instances, one or more features in a claimed combination can be excluded from the combination, and the combination can be claimed as a subcombination or a variation of the subcombination.

[0068] Furthermore, although operations may be shown in the figures or described herein in a particular order, such operations need not be performed in the particular order shown or in sequential order, or all of the operations need not be performed to achieve a desired result. Other operations not shown or described may be incorporated into the example methods and processes. For example, one or more additional operations may be performed before, after, simultaneously with, or between any of the described operations. Furthermore, these operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps performed in the illustrated and / or disclosed processes may differ from those shown in the figures. In some embodiments, some of the steps described above may be omitted, and other steps may be added. Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form further embodiments, all of which are within the scope of the present disclosure. It should also be understood that the separation of various system components in the above-described implementations is not to be understood as requiring such separation in all implementations, and that the described components and systems may generally be integrated together in a single product or packaged into multiple products.

[0069] In the present disclosure, certain aspects, advantages, and novel features are described herein. Not all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, one skilled in the art will recognize that the present disclosure may be embodied or practiced to achieve one advantage or group of advantages as taught herein, but without necessarily achieving other advantages as may be taught or suggested herein.

[0070] Conditional expressions such as "can," "could," "might," "may," and the like, unless expressly stated otherwise or understood otherwise within the context in which they are used, are generally intended to convey that certain embodiments include certain features, elements, and / or steps and that other embodiments do not include such features, elements, and / or steps. Thus, such conditional language is generally not intended to imply that features, elements, and / or steps are necessarily required for one or more embodiments, or that one or more embodiments necessarily include logic for determining whether or not those features, elements, and / or steps are included in or will be performed in any particular embodiment, with or without the user's information or affirmative suggestion.

[0071] Conjunctive phrases such as "at least one of X, Y, and Z," unless expressly stated otherwise, are understood in the context in which they are otherwise commonly used to convey that an item, term, etc. can be either X, Y, or Z. Thus, such conjunctive phrases are not generally intended to suggest that a particular embodiment requires that at least one X, at least one Y, and at least one Z be present.

[0072] Degree expressions used herein, such as the terms "approximately," "about," "substantially," and "substantially," as used herein, refer to a value, amount, or characteristic that is close to a stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms "about," "substantially," and "substantially" can refer to an amount that falls within a range of less than 10%, less than 5%, less than 1%, less than 0.1%, or less than 0.01% of a stated amount. In another example, in certain embodiments, the terms "approximately parallel" and "substantially parallel" refer to a value, amount, or characteristic that deviates from exact parallelism by 15 degrees or less, by 10 degrees or less, by 5 degrees or less, by 3 degrees or less, by 1 degree or less, or by 0.1 degrees or less.

[0073] The scope of the present disclosure is not intended to be limited by the specific disclosure of preferred embodiments in this section or elsewhere herein, but may be defined by the claims as they are presented or may be presented in the future, either in this section or elsewhere herein. The language of the claims should be interpreted broadly based on the language used in the claims and should not be limited to the examples described in this specification or during the course of this application, which examples should be interpreted as non-exclusive. [Explanation of symbols]

[0074] 10 Vehicles 90 Fuel System 100 Gas cylinder assembly, tank gas cylinder assembly 110 Stiffening structure 120 Internal pressure seal, inner liner assembly, inner liner, liner 124 First end portion 125 Second end portion 126 Central body, central section 127 Exterior 128 Welding Line 129 Inside 130 Intermediate Assembly 130-1 Intermediate Assembly 130-2 Intermediate Assembly 130-3 Intermediate Assembly 130-4 Intermediate Assembly 130-5 Intermediate Assembly 134 Permeable barrier layers, tapes, ribbons, 134-1 Barrier Material Strips 134-2 Permeability barrier layer 134-3 Barrier Material Strips 134-4 Permeability barrier layer 134-5 Permeability barrier layer 134-6 Permeability barrier layer 134-7 First Part 134-8 Second Part 136 Permeability Barrier Layer 142 Neck 143 Neck 144 First Boss 150 Border 162 dome-shaped end portion, first dome-shaped end portion, first dome-shaped member, dome-shaped structure 163 Dome-shaped end portion, second dome-shaped member, dome-shaped structure 181 first end portion, first polymer compound layer, longitudinal end portion 182 Metal foil 183 second end portion, second polymer compound layer, longitudinal end portion 184 Adhesive layer 200 central part 210 End part 220 End part 232 Dome-shaped structure 233 Dome-shaped structure 300 Interior space

Claims

[Claim 1] 1. A gas cylinder for containing compressed gas, comprising: A first end portion; A second end portion; and a central body having a first end connected to the first end portion and a second end connected to the second end portion, the central body having an outer surface and an inner surface disposed between the first end and the second end; An internal pressure sealing body comprising: the first end portion, the second end portion and the central body forming a sealed cavity for storing the compressed gas, the inner surface of the central body forming at least a portion of an innermost surface of the internal pressure seal; the central body disposed between the inner surface and the outer surface being a continuous surface of a homogenous material; a stiffening structure disposed over the central body; a metal foil interposed between the stiffening structure and the central body, the metal foil being configured to reduce permeation of the contents of the internal pressure seal; A gas cylinder comprising:

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