Curved and conformal high-pressure vessel

A high-pressure vessel is provided. The high-pressure vessel may comprise a first chamber defined at least partially by a first wall, and a second chamber defined at least partially by the first wall. The first chamber and the second chamber may form a curved contour of the high-pressure vessel. A modular tank assembly is also provided, and may comprise a first mid tube having a convex geometry. The first mid tube may be defined by a first inner wall, a curved wall extending from the first inner wall, and a second inner wall extending from the curved wall. The first inner wall may be disposed at an angle relative to the second inner wall. The first mid tube may further be defined by a short curved wall opposite the curved wall and extending from the second inner wall to the first inner wall.

FIELD OF INVENTION

The present disclosure relates to high-pressure vessels, and, more specifically, to a curved and conformal high-pressure vessel.

BACKGROUND

Many engines rely on energy sources that are stored in storage tanks. For example, automobiles, aircraft, and boats may rely on storage tanks to store fuels such as gasoline, compressed natural gas, and propane. Similarly, compressed gasses such as nitrogen and carbon dioxide may be stored in tanks. The industry use of cylinders for compressed natural gas, for example, is limited at least in part because large, bulky cylinders fill large volumes and reduce available cargo space. Cylindrical tanks have a conformability ratio (i.e., the ratio of overall tank volume to equivalent rectangular envelope) of approximately 70%. The inefficient use of onboard vehicle space may decrease the volume efficiency of current cylindrical tanks.

SUMMARY

A high-pressure vessel may comprise a first chamber defined at least partially by a first wall, and a second chamber defined at least partially by the first wall. The first chamber and the second chamber may form a curved contour of the high-pressure vessel.

In various embodiments, the first chamber may be at least partially defined by a second wall oriented at an acute angle relative to the first wall. A curved wall may be at least partially defining the first chamber, and a circular wall may at least partially define the second chamber, wherein the curved wall and the circular wall meet at a substantially 120° angle. The circular wall, the first wall, and the curved wall may have a same thickness. The curved contour may comprise at least one of an S-shaped contour, a multi-radial contour, or a non-uniformly curved contour. The first chamber may be a mid tube and the second chamber may be an end tube. The end tube and the mid tube may be welded together. The end tube and the mid tube may also comprise at least one of aluminum, steel, or composite.

A modular tank assembly may comprise a first mid tube having a convex geometry. The first mid tube may be defined by a first inner wall, a curved wall extending from the first inner wall, and a second inner wall extending from the curved wall. The first inner wall may be disposed at an angle relative to the second inner wall. The first mid tube may further be defined by a short curved wall opposite the curved wall and extending from the second inner wall to the first inner wall. A second mid tube has a second convex geometry and defined at least partially by the first inner wall.

In various embodiments, the second mid tube may further comprise a second curved wall that meets the curved wall of the first mid tube at a 120° angle. The first inner wall, the second inner wall, the curved wall, and the short curved wall may have an equal thickness. The modular tank assembly may have at least one of an S-shaped, multi-radial, curved, or non-uniformly curved contour. An end tube may be coupled to the first mid tube and have a circular wall that meets the curved wall at a 120° angle. The first inner wall may at least partially define the end tube. The first mid tube and the second mid tube may be welded together.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the exemplary embodiments of the disclosure, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein. Thus, the detailed description herein is presented for purposes of illustration only and not limitation. The steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented.

Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Also, any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. Surface shading lines may be used throughout the figures to denote different parts but not necessarily to denote the same or different materials.

With reference toFIGS. 1-3, a high-pressure vessel100is shown with outer surface102spanning across end tubes104, intersections112, and mid tubes106, in accordance with various embodiments. High-pressure vessel100may comprise a curved contour produced by the geometry of each end tubes104and mid tubes106. End tubes104may be capped by end cap108having a spherical contour. Mid tubes106may be capped by end caps110having a substantially spherical contour. Intersections112may join end tubes104and mid tubes106together. Each mid tubes106and end tubes104may be fabricated separately and welded together to form high-pressure vessel100.

In various embodiments, end-tube body105may be an elongated, concave body having a partially circular cross section that defines a chamber124when joined with end cap108. Similarly, mid-tube body107may be an elongated, concave body having a substantially trapezoidal cross section that defines a chamber126when joined with end cap110. Chamber124and chamber126may each be partially defined by inner wall122. Chamber124and chamber126may also define a curved contour of high-pressure vessel100, described further below. In that regard, a chamber may be a mid tube or end tube. As shown in the cross-sectional view ofFIG. 2, end tubes104may have a D-shape comprising a circular wall120and an inner wall122having a flat and straight geometry. Inner wall122and circular wall120may extend an end cap108(with momentary reference back toFIG. 1) at a first end of end-tube body105to a second end cap108at the opposite side of end-tube body105. The D-shaped end tubes104may be disposed at either end103of high-pressure vessel100with one or more mid tubes106coupled between end tubes104.

In various embodiments, mid tubes106may have a trapezoidal cross section comprising a curved wall128, two flat and straight inner walls122extending inward from either end of curved wall128, and a short curved wall130that meets the inner walls122at a location opposite curved wall128. The length L2along surface107of short curved wall130may be less than the length L1of curved wall128. In that regard, inner walls122tend to be disposed closer together at positions closer to short curved wall130. Similarly, inner walls122tend to be disposed further apart at positions closer to curved wall128. Inner wall122and circular wall120may extend from an end cap110at a first end of mid-tube body107to a second end cap110at the opposite side of mid-tube body107. The mid tubes106may be disposed central to two end tubes104of high-pressure vessel100. In that regard, an end tube104may share an inner wall122with mid tube106disposed adjacent the end tube104.

With reference toFIG. 3, relationships between internal and external walls of high-pressure vessel100are shown, in accordance with various embodiments. Circular wall120, inner wall122and curved wall128meet at an intersection112. Circular wall120, short curved wall130, and inner wall122also meet at an intersection112. Similarly, inner wall122may meet with two short curved walls130at an intersection112. Inner wall122may also meet two curved walls128at an intersection112.

In various embodiments, each intersection112has a Y-shaped geometry when viewed in cross section. The Y-shape comprises an angle α defined by the tangent lines of circular walls120, curved walls128, and/or short curved walls130at an intersection112where the walls meet. The contours of circular walls120, curved walls128, and/or short curved walls130may be selected to ensure that angle α is always substantially 120°. Substantially 120° is used to mean 120°+/−5°, with each 120° referred to herein being substantially 120°. Circular walls120, curved walls128, and/or short curved walls130angled at 120° along intersections112transfer load from the outer hoop or outer walls of high-pressure vessel100inward to a tensile load direction (i.e., along inner walls122). In that regard, inner walls122may share the stress loads on high-pressure vessel100and produce substantially uniform stress loads along surfaces of the high-pressure vessel.

In various embodiments, each wall in high-pressure vessel100may have a uniform thickness T. That is, circular wall120, inner wall122, curved wall128, and short curved wall130may each have thickness T that is substantially equal to the other walls. The thickness T may be selected to provide a balance between strength and weight of high-pressure vessel100and to sustain a desired internal pressure. The combination of substantially equal and uniform wall thickness with 120° intersection of outer walls (i.e., circular wall120, short curved wall130, and curved wall128) and inner supports (i.e., inner wall122) produces load sharing of the pressure load where the inner diameter stress S, of the wall is hoop stress of a similarly sized cylinder. Each inner wall122may be set an acute angle relative to other inner walls122, with the angle determined by the number of segments need to make up the total angle of the assembly.

In various embodiments, the stress in the inner wall122is tensile and is essentially equal to the hoop stress of the inner surfaces of circular wall120, short curved wall130, and curved wall128. A stress of slightly greater magnitude may exist localized near the fillet at intersection112of the outer wall to inner support. The fillet can be sized to minimize the effect of the stress concentration caused by change of the load path in the wall. The expected increase of tank conformability (i.e., the ratio of overall tank volume to equivalent rectangular envelope) to as much as 92% provides volume efficiency with additional flexibility to place tank against curved structures (e.g., a boat hull or an aircraft fuselage). The higher conformability increases the amount of gas that can be stored in a given space.

In various embodiments, high-pressure vessel may be formed from high-strength materials or light weight metals to allow for thinner walls and lower weights than might be realized with lower-strength materials such as aluminum, steel, or composites. For example, high-pressure vessel100may be fabricated using high-strength, 7000 series aluminum (i.e., aluminum alloyed with zinc and optionally precipitate hardened) or high-strength steel. Referring toFIGS. 1-3, each mid tube106and end tube104may be formed independently of other mid tubes and end tubes and subsequently welded together to form high-pressure vessel100. In that regard, high-pressure vessel100may be a modular tank assembly.

In various embodiments, the core of high-pressure vessel could be manufactured from an integral extrusion of the entire cross section including mid tubes106and end tubes104. The core of high-pressure vessel100could also be formed as individual segments that are bonded together. Bonding methods could be any fusion or solid state method used for joining metals, including, but not limited to Tungsten Inert Gas (TIG), laser electron beam, friction stir welding, or flash upset butt welding. The end caps108and110are essentially spherical in shape except for where the inner wall122needs to be positioned. The end caps108and110could be manufactured as part of the core using forging, hydroforming, or other extrusion method, or individually and bonded to the core.

In various embodiments, high-pressure vessel100may also be formed using composite materials. Chopped fiber, a hybrid of chopped and continuous fiber, continuous fiber, and/or fiber fabric may be used to form high-pressure vessel100. The composite material may be formed with a resin and the fiber formed into the shape of high-pressure vessel100. Each end tube104and mid tube106may be formed, for example, by placing pre-impregnated composite fibers around a mandrel in the shape of each end tube104or mid tube106. End tubes104and mid tubes106may then be pressed together with an additional layer and the pre-impregnated composite material wrapped around the outer surfaces of end tubes104and mid tubes106to ensure uniform wall thickness. The entire high-pressure vessel100, including end caps108and110may be cured as a unitary composite structure using a pressurized autoclave.

With reference toFIGS. 4A-4C, high-pressure vessels are shown in non-uniformly curved configurations, in accordance with various embodiments. InFIG. 4A, high-pressure vessel150is formed with its cross section following non-uniform curve178(i.e., a multi-radial curve or non-radial curve). End tubes152are disposed with high-angle mid tube156, mid tube166, and slightly angled mid tube172coupled between end tubes152. End chamber162may be defined by circular wall154and inner wall160. Inner walls160may be angled relative to one another at different angles to produce non-uniform curve178. Curved wall158may meet circular wall154at an intersection with the tangent of each surface at the intersection meeting at an angle of 120°. Each intersection between curved wall158, curved wall168, curved wall174, short curved wall164, short curved wall170, short curved wall176, and circular wall154may be formed with the walls meeting at a 120° angle relative to one another. Mid tubes of high-pressure vessel150may each have a different geometry to provide non-uniform curve178. Each wall in high-pressure vessel150may have substantially similar thickness (as shown inFIG. 3) and meet at 120° intersections to provide uniform stress loads throughout high-pressure vessel150.

With reference toFIG. 4B, a high-pressure vessel180is shown having a symmetric and multi-radial contour, in accordance with various embodiments. End tubes182are disposed with high-angle mid tube190, mid tube198, and slightly angled mid tubes206coupled between end tubes182. End tube182may be defined by circular wall184and inner wall192. Inner walls192may be angled relative to one another at different angles to produce multi-radial curve202. Curved wall188may meet circular wall184at an intersection with the tangent of each surface at the intersection meeting at an angle of 120°. Each intersection between curved wall188, curved wall200, curved wall208, short curved wall194, short curved wall210, and circular wall184may be formed with the walls meeting at a 120° angle relative to one another. Mid tubes of high-pressure vessel150may each have a different geometry to provide multi-radial curve202. Each wall in high-pressure vessel150may have substantially similar thickness (as shown inFIG. 3) and meet at 120° intersections to provide uniform stress loads throughout high-pressure vessel150.

With reference toFIG. 4C, a high-pressure vessel230is shown having an s-shaped contour, in accordance with various embodiments. End tubes232are disposed with angled mid tubes240and straight mid tube250coupled between end tubes232. End tube232may be defined by circular wall234and inner wall236. Inner walls236may be angled relative to one another at different angles to produce multi-radial curve202. Parallel inner walls256may be substantially parallel to one another to form a straight mid tube250that does not curve. Parallel inner walls256may also be disposed at angles relative to inner walls236. Curved wall242may meet circular wall234at an intersection with the tangent of each surface at the intersection meeting at an angle of 120°. Each intersection between curved wall242, curved wall252of straight mid tube250, curved wall254of straight mid tube250, short curved wall244, and circular wall234may be formed with the walls meeting at a 120° angle relative to one another.

In various embodiments, curved wall252and curved wall254of straight mid tube250may have substantially similar lengths to span between parallel inner walls256. Mid tubes of high-pressure vessel230may each have a different geometry to provide s-shaped curve246. Each wall in high-pressure vessel150may have substantially similar thickness (as shown inFIG. 3) and meet at 120° intersections to provide uniform stress loads throughout high-pressure vessel150.