Patent Application
20150362125
The present disclosure relates generally to a composite pressure vessel.
Pressure vessels, such as, e.g., gas storage containers and hydraulic accumulators may be used to contain fluids under pressure. It may be desirable to have a pressure vessel with relatively thin walls and low weight. For example, in a vehicle fuel tank, relatively thin walls allow for more efficient use of available space, and relatively low weight allows for movement of the vehicle with greater energy efficiency. Further, a thinner wall tank allows for faster heat exchange during refueling, thereby allowing better thermal management.
A composite pressure vessel includes a liner to contain a pressurized fluid and a composite layer formed on at least a portion of an exterior surface of liner. The composite layer includes a third generation advanced high strength steel filament reinforcement embedded in a polymer matrix.
Features and advantages of examples of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to similar, though perhaps not identical, components. For the sake of brevity, reference numerals or features having a previously described function may or may not be described in connection with other drawings in which they appear.
As used herein, the word “filament” means a single fiber, wire, flat wire, or low, flat profile band. A single continuous filament that may be rolled on a spool is a “monofilament” as used herein. Filaments in a bunch are called a “strand” or an “end.” If the filaments are all parallel to each other, the “end” is called a “roving,” although graphite rovings are also referred to as “tows.” If the filaments are twisted to hold the fibers or wires together, the bundle is called a “yarn.”
Either roving (tow) or yarn can be woven into a fabric. If roving is used, the fabric is called “woven roving;” if yarn is used, the fabric is called “cloth.” Although the terms “yarn” and “roving” are not interchangeable, where the word “yarn” is applied in this document, it is to be understood that “roving” may be applied also. Nonwoven fabric is a fabric-like material such as “felt” made from long fibers, bonded together by chemical treatment, mechanical treatment, heat treatment, or solvent treatment.
In a roll of fabric, “warp yarns” run in the direction of the roll and are continuous for the entire length of the roll. “Fill yarns” run crosswise to the roll direction. Warp yarns are usually called “ends” and fill yarns “picks.” (The terms apply equally to rovings, but yarn will be used in the rest of the discussion for simplicity.)
Fabric count refers to the number of warp yarns (ends) and fill yarns (picks) per inch. For example, a 24×22 fabric has 24 ends in every inch of fill direction and 22 picks in every inch of warp direction. Note that warp yarns are counted in the fill direction, and fill yarns are counted in the warp direction.
If the end and pick counts are roughly equal, the fabric is considered “bidirectional” (BID). If the pick count is very small, most of the yarns run in the warp direction, and the fabric is nearly unidirectional. Some unidirectional cloths have no fill yarns; instead, the warp yarns are held together by a thin stream of glue. “Unidirectional prepreg” relies on resin to hold the fibers or wires together.
“Weave” describes how the warp and fill yarns are interlaced. Examples of weaves are “plain,” “twill,” “harness satin,” and “crow-foot satin.” Weave determines drapeability and isotropy of strength.
“Composite material” means engineered material made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct on a macroscopic level within the finished structure. There are two categories of constituent materials: matrix and reinforcement. The matrix material surrounds and supports the reinforcement material by maintaining their relative positions. The reinforcements impart their special mechanical and physical properties to enhance the matrix properties. A synergism produces material properties unavailable from the individual constituent materials.
Reinforcement materials include fiberglass, carbon fiber, aramid fiber and the like. As disclosed herein, reinforcement material may also include metal filaments, e.g. steel and third generation nanostructured steel filaments.
A polymer matrix material is often called a resin solution. The most commonly known polymer matrix materials are polyesters, vinyl esters, epoxies, phenolic polymers, polyimides, polyamides, polypropylenes, polyether ether ketone (PEEK), and the like. It is to be understood that these polymer examples are not intended to be limiting, and that other materials are contemplated as being within the purview of the present disclosure.
“Full-wrapped” means applying the reinforcement of a filament or resin system over the entire liner, including the domes.
“Hoop-wrapped” means winding of filament in a substantially circumferential pattern over the cylindrical portion of the liner so that the filament does not transmit any significant stresses in a direction parallel to the cylinder longitudinal axis.
“Liner” means an inner, gas tight container or gas cylinder to which the overwrap is applied.
“Service pressure (S.P.)” means an internal settled pressure of a CNG fuel container at a uniform gas temperature of 70° F. (21° C.) and full gas content. It is the pressure for which the container has been constructed under normal conditions.
“Burst pressure” means a highest internal pressure reached in a CNG fuel container during an FMVSS 304 burst test at a temperature of 70° F. (21° C.).
“Burst ratio” means a ratio of burst pressure to service pressure.
Some pressure vessels are categorized by the International Standards Organization (ISO) 11439 Gas cylinders—High pressure cylinders for the on-board storage of natural gas as a fuel for automotive vehicles. ISO 11439 has four categories for Compressed Natural Gas (CNG) cylinders: Type I, Type II, Type III, and Type IV. These four categories are also seen in other standards including Federal Motor Vehicle Safety Standard (FMVSS) 304, and NGV2 (Natural Gas Vehicle). The CNG cylinders of all four categories are cylindrical with one or two domed ends.
The Type I cylinder 30, depicted in
The Type II cylinders 30′, depicted in
The Type III cylinders 30″, depicted in
The Type IV cylinders 30′, depicted in
Third Generation Advanced High Strength Steel (AHSS) means types of steel with strength-ductility combinations substantially better than exhibited by the first generation AHSS but at a cost substantially less than the cost corresponding to second generation AHSS. The strength-ductility combination of various types of steel are depicted on the Percent Elongation (δ) vs. Tensile Strength (TS) diagram in
In Table 1, steel types having a generation of 0 are not considered AHSS. Third Generation AHSS has Percent Elongation δ and Tensile Strength TS characteristics that generally fall between First Generation AHSS and Second Generation AHSS. Third Generation AHSS has Percent Elongation δ and Tensile Strength TS characteristics that are substantially bounded by the Third Generation Ellipse 123 in
Applying the parameters of the Third Generation Ellipse 123 in
Which simplifies to:
Therefore, the third generation AHSS has combinations of Percent Elongation δ and Tensile Strength TS bounded by the solutions of Eq. 3. Examples of the composite pressure vessel of the present disclosure may include a third generation AHSS filament with a Percent Elongation δ and a corresponding Tensile Strength TS bounded by solutions to Eq. 3. In Eq. 3, the Tensile Strength, TS is in units of MegaPascals (MPa).
Examples of the present disclosure may include a third generation AHSS filament having a tensile strength from about 800 MPa to about 1600 MPa and respective elongation δ from about 10 percent to about 60 percent.
An example of a third generation AHSS is Carbide-Free Bainitic (CFB) steel. Another example of a third generation AHSS is Quench and Partition (QP) Boron steel, also known as QP B-steel. Yet another example of a third generation AHSS is NanoSteel (NS), available from The NanoSteel Company, Inc., Providence, R.I. In examples of the composite pressure vessel of the present disclosure, the third generation AHSS filament may be, e.g. NanoSteel, Carbide-Free Bainitic (CFB) steel or Quench Partitioned Boron steel.
Referring now to
By including the third generation AHSS filaments 74 in the composite layer 70, examples of the composite pressure vessel 10 of the present disclosure may have better thermal management characteristics when compared to the carbon, glass, and aramid fiber reinforced composites of conventional Type II, III and IV tanks. When gas cylinders are filled to pressures in the range of 20 MPa to 25 MPa, the gas tends to heat up, temporarily lowering the mass of the gas that can be added at a particular pressure. The third generation AHSS filaments 74 conduct heat better than carbon, glass, and aramid fiber. The better heat conduction allows the mass of fuel in the composite pressure vessel 10 of the present disclosure to cool more quickly, thereby increasing the mass of fuel that can be added at a particular pressure when compared to a conventional Type II, III, or IV tank.
In examples of the present disclosure, the third generation AHSS filament 74 may be helically wound upon at least a portion of the exterior surface 62 as depicted in
Examples of the composite pressure vessel 10, 10′ of the present disclosure may include a liner 50, 50′ formed from a metal. For example, the metal may be a steel alloy or an aluminum alloy. A thin (less than 0.002 inch) layer of another metal or plastic may be plated or deposited onto the interior surface 61 of the metal liner to improve chemical compatibility with the fluid contained by the composite pressure vessel 10, 10′. In other examples, the liner 50″ may be formed from a polymer. In some examples, the polymeric liner may have a thin layer of a metal deposited on an interior surface 61 to reduce permeation of the fluid through the polymeric liner 50″. In other examples, the polymeric liner 50″ does not have a thin layer of metal deposited on the interior surface 61.
The liner 50, 50′, 50″ may be seamless or may be made by attaching or welding sections together, or by using rolled and welded tubing. In an example, the liner 50″ (see
Referring to
In an example, each tank sub-unit 20 may be a primary parallelohedron. As such, the tank sub-units 20 may tessellate a 3-dimensional space. A uniform tessellation which fills three-dimensional Euclidean space with non-overlapping convex uniform polyhedral tank sub-units is also known as a convex uniform honeycomb. A honeycomb having all sub-units identical within its symmetries is isochoric. A sub-unit of an isochoric honeycomb is a space-filling polyhedron. Examples of space-filling polyhedra include: regular packings of cubes, hexagonal prisms, and triangular prisms; a uniform gyrated triangular prismatic honeycomb; a uniform packing of truncated octahedra; a rhombic dodecahedral honeycomb; a triakis truncated tetrahedral honeycomb; a trapezo-rhombic dodecahedral honeycomb; an elongated dodecahedron honeycomb; and a packing of any cuboid, rhombic hexahedron or parallelepiped.
As shown in
The liner 50 may have a cylindrical portion 72 and a dome 73 sealingly engaged with a first end 83 of the cylindrical portion 72 (see
The third generation AHSS filament 74 may be circumferentially or helically wound upon the cylindrical portion 72. The third generation AHSS filament 74 may be circumferentially or helically wound over the cylindrical portion 72, the first dome 73, and the second dome 75. The composite pressure vessel 10, 10′, 10″, 10′″ may be to have a burst ratio of a burst pressure to the service pressure ranging from about 2.25 to about 3.50. For example, if the service pressure is about 20 MPa, the burst pressure would range from about 45 MPa to about 70 MPa. In examples, the service pressure may range from about 20 MPa to about 25 MPa.
The composite pressure vessel 10, 10′, 10″, 10′″ may be used to contain pressurized fluid (not shown). It is to be understood that fluids contained by the composite pressure vessel assembly 10, 10′, 10″, 10′″ may be liquids, gases, mixtures, solutions, and combinations thereof. Materials contacted by the fluids contained by the composite pressure vessel assembly 10, 10′, 10″, 10′″ may be selected to be chemically compatible with the fluid. In an example, the composite pressure vessel 10, 10′, 10″, 10′″ may be a fuel tank.
It is to be understood that the ranges provided herein include the stated range and any value or sub-range within the stated range. For example, a range of from about 10 percent to about 60 percent should be interpreted to include not only the explicitly recited limits of about 10 percent to about 60 percent, but also to include individual values, such as 20 percent, 31.3 percent, etc., and sub-ranges, such as from about 15 percent to 48 percent, etc. Furthermore, when “about” is utilized to describe a value, this is meant to encompass minor variations (up to +/−10%) from the stated value.
Reference throughout the specification to “one example”, “another example”, “an example”, and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the example is included in at least one example described herein, and may or may not be present in other examples. In addition, it is to be understood that the described elements for any example may be combined in any suitable manner in the various examples unless the context clearly dictates otherwise.
In describing and claiming the examples disclosed herein, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.
While several examples have been described in detail, it will be apparent to those skilled in the art that the disclosed examples may be modified. Therefore, the foregoing description is to be considered non-limiting.
