Patent Description:
The present invention relates to a boss for Type IV pressure vessels including Type IV conformable pressure vessels. More particularly, the invention relates to boss designs having spikes embedded into an outer composite shell and wherein the liner is positioned inside of the boss.

Pressure vessels commonly store fluids and/or gases under pressure, such as natural gas, oxygen, nitrogen, hydrogen, propane, and the like. Type IV pressure vessels or tanks have a metal-free body typically comprising a carbon fiber reinforced polymer composite wound and/or braided over a thermoplastic polymeric liner. A valve is coupled to the vessel for filling the vessel with compressed fluid. However, the valve cannot be connected directly to the polymer liner. Therefore, a boss needs to be provided to couple the valve to the vessel.

A first known method of forming a type IV pressure vessel by attaching a boss to a polymeric liner and an outer composite shell is illustrated in <CIT>. The first known method utilizes an injection molding process to mold the liner around locking features of the boss to mechanically lock the boss to the liner. This first known method provides excellent surface contact between the polymeric liner and the outer surface of the boss. A seal between the liner and the boss is formed by an interface between the liner and the boss. Further, the boss typically includes a lip feature that seals against itself when the boss is pressurized. The gas-tight boss / liner assembly is supported by an outer covering of a composite shell. The sealing mechanism and the mechanical restriction are not coupled. The joint between the boss and the liner is not pre-stressed.

However, this first known method requires molding the liner around the boss prior to wrapping the liner with the composite fibers. Further, the first known method lacks mechanical engagement between the boss and the outer composite shell. As such, the boss can separate from the outer composite shell under stress, allowing the boss to rotate within the outer composite shell and/or slide axially with respect to the outer composite shell. Movement of the boss with respect to the liner and/or the outer composite shell can result in leakage and potentially failure of the connection between the boss and the pressure vessel.

A second known method of forming a boss of a type IV pressure vessel is illustrated in <CIT>, wherein a hose-style crimp, such as a ferrule, is crimped around a layered assembly of an outer composite shell, a polymeric liner, and a boss-. The second known method includes a boss that slides within an opening in the liner such that the liner is positioned against an outer surface of the boss. A ferrule is crimped around the boss and the composite shell after the liner is covered with the outer composite shell to fixedly couple the boss to the outer composite shell. The boss can include ridges along an outer surface of the boss to grip an inner surface of the liner. The hose-style crimp fittings rely on crimp pressure to provide composite anchoring and sealing. Gas trying to escape along the liner tends to open a gap between the boss and the liner. The ferrule and the composite are pre-stressed to a state resisting the gap opening. The ferrule is also stressed axially by providing grip on the composite and resisting the stem axial displacement.

However, this second known method relies on the crimp pressure to fixedly couple the boss to the liner. The boss can rotate within the liner under increased load on the boss if there is insufficient crimping force on the joint between the boss and the liner. Further, the second known method lacks mechanical engagement directly between the boss and the outer composite shell and relies on the ferrule to fixedly couple the boss to the outer composite shell. Axial load and rotational load on the boss can weaken the connection between the boss and the outer composite shell. The boss can separate from the outer composite shell under stress, allowing the boss to rotate within the outer composite shell and/or slide axially with respect to the outer composite shell. Movement of the boss with respect to the liner and/or the outer composite shell can result in leakage and potentially failure of the connection between the boss and the pressure vessel.

Reference is made to patent document <CIT>, which relates to a prior art composite pressure vessel having a gas-tight inner envelope with an end fitted with a rigid reinforcing member.

Reference is made to patent document <CIT>, which relates to a prior art composite pressure vessel with a boss connector.

Reference is made to patent document <CIT>, which relates to a prior art method of producing a high pressure tank.

It is desirable, therefore, to mechanically couple a boss directly to an outer composite shell of a type IV pressure vessel. Further, it is desirable to mechanically couple the boss directly to a liner of the pressure vessel. It is desirable to form a seal between the liner and the boss. It is also desirable to restrict rotational movement of the boss with respect to the liner and with respect to the outer composite when torque is applied to the boss. Further, it is desirable to restrict axial movement of the boss with respect to the liner and to the outer composite shell when axial force is applied to the boss. In addition, it is desirable to fixedly couple the liner to the boss without using a molding process and without requiring the use of a ferrule to crimp the liner to the boss. Finally, it is desirable to fixedly couple the outer composite shell to the boss without relying on a ferrule to crimp the outer composite shell to the boss.

A type IV pressure vessel is provided that has improved mechanical coupling between an outer composite shell and a boss. The pressure vessel comprises an inner polymeric liner having a flare edge fixedly coupled to the boss. The boss has a bore in fluid communication with an interior of the pressure vessel. In addition, the boss has a shank extending between the liner and the outer composite shell. The shank includes a plurality of spikes projecting radially away from the boss. The outer composite shell of resin and fiber surrounds an outer periphery of the liner and an outer periphery of the shank. The spikes are embedded into the outer composite shell to mechanically fasten the outer composite shell to the boss.

Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, a type IV pressure vessel (with polymeric liner <NUM> and outer composite shell <NUM>) <NUM> for containing liquids and/or gases under pressure is shown in <FIG> and <FIG>, according to one embodiment of the present invention. The pressure vessel <NUM> is suitable for storage of compressed liquids and/or gases, such as nitrogen, hydrogen, natural gas, helium, dimethyl ether, liquefied petroleum gas, xenon, and the like. A pressure vessel <NUM> for storage of hydrogen for automotive applications typically is designed for up to 70MPa of nominal working pressure. In comparison, pressure vessels <NUM> for storage of compressed natural gas are typically designed for up to 25MPa of nominal working pressure.

Referring to <FIG> and <FIG>, the pressure vessel <NUM> includes a polymeric liner <NUM> fixedly coupled to a boss <NUM> with an outer composite shell <NUM> surrounding an outer periphery <NUM>' of the polymeric liner <NUM>. The liner <NUM> comprises an interior hollow body <NUM> defined by an elongated cylindrical wall <NUM> extending between a first terminal end <NUM> and a second terminal end <NUM>. The longitudinal axis of the pressure vessel <NUM> is shown by element <NUM>. In the embodiment shown in <FIG>, the liner <NUM> includes a neck region <NUM>, a taper region <NUM>, and a chamber region <NUM>. The polymeric liner <NUM> includes opposing inner and outer surfaces <NUM>, <NUM> and an inlet opening <NUM> at the first terminal end <NUM>. The inlet opening <NUM> of the liner <NUM> includes a flare edge <NUM> that is fixedly coupled to the boss <NUM> with the sealing insert <NUM>.

The polymeric liner <NUM>, shown in <FIG>, is generally formed from one or more polymeric materials such as Nylon (PA), ethylene-vinyl acetate (EVA), linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), ethylene vinyl alcohol (EVOH), polytetrafluoroethylene (PTFE), polyurethane (PU), and/or polyvinyl chloride (PVC). The polymeric liner <NUM> may be formed of a single layer of polymeric material or may comprise a multi-layered structure of two or more polymeric layers and further may include one or more metal layers or additives, as desired for specific applications.

The boss <NUM> of <FIG> is shown in <FIG> removed from the pressure vessel <NUM>. Referring to <FIG> and <FIG>, the boss <NUM> has a bore <NUM> passing axially through the boss <NUM> between opposing terminal ends <NUM>, <NUM>' of the boss <NUM>. The longitudinal axis of the boss <NUM> is shown by element <NUM> in <FIG>. The bore <NUM> is comprised of a neck portion <NUM>, a cone surface <NUM> and a mating surface <NUM>. The boss cone surface <NUM> can include one or more fine ridges 102A, a rough surface texture 102B, and/or a smooth surface texture 102C, as illustrated in <FIG>, respectively. In the embodiment shown in <FIG> and <FIG>, the flare edge <NUM> of the liner <NUM> is fixedly coupled to and sealed against the cone surface <NUM>.

The flare edge <NUM> of the liner <NUM> conforms to the cone surface <NUM>. The flare edge <NUM> is formed during liner <NUM> extrusion process or formed or thermoformed directly against the cone surface <NUM> of the boss <NUM>. The neck section <NUM> of the liner <NUM> conforms to the neck portion <NUM>. The neck section <NUM> is formed during a liner <NUM> extrusion process and can be additionally thermoformed against the neck portion <NUM> to enhance the seal.

A sealing insert <NUM>, shown in <FIG> and <FIG>, is shaped to fit within and engage with the mating surface <NUM> of the boss <NUM>. The sealing insert <NUM> of <FIG> is shown in <FIG> prior to assembly with the boss <NUM>. Referring to <FIG>, the sealing insert <NUM> has a generally cylindrical main body portion <NUM> with a mating surface <NUM> extending around an outer periphery of the cylindrical main body portion <NUM> configured to meshingly engage with the mating surface <NUM> by means of threads, press fit, swaging, or the like. The longitudinal axis of the sealing insert <NUM> is shown by element <NUM> in <FIG>.

Further, the sealing insert <NUM> includes a bore <NUM> passing axially through the sealing insert <NUM>. Extending from the main body portion <NUM> of the sealing insert <NUM> is a cone surface <NUM> configured to seal against the flare edge <NUM> of the liner <NUM>. The cone surface <NUM> can include one or more fine ridges 162A, a rough surface texture 162B, and/or a smooth surface texture 162C, as illustrated in <FIG>, respectively.

Also shown in <FIG>, when the sealing insert <NUM> is engaged with the mating surface <NUM> of the boss <NUM>, the flare edge <NUM> of the liner <NUM> is compressed between an outer surface <NUM> of the sealing insert <NUM> and the boss cone surface <NUM> of the bore <NUM> to provide the seal.

The compression applied by the sealing insert <NUM> against the flare edge <NUM> of the liner <NUM> forms a seal between the liner <NUM> and the boss cone surface <NUM> of the boss <NUM>, as shown in <FIG>. Pinching the liner <NUM> between the bore <NUM> and the sealing insert <NUM> forms an initial seal between the boss <NUM> and the liner <NUM>. The neck portion <NUM> forms a seal with the liner <NUM> outer surface <NUM> after the liner <NUM> is pressurized.

Alternatively, one or more supplemental seals, such as an O-ring and the like, can be included adjacent the liner <NUM>, the bore <NUM>, and/or the sealing insert <NUM> if desired for specific applications. The seal between the liner <NUM> flare edge <NUM>, the boss cone surface <NUM>, and the sealing insert <NUM> can be improved by including a rough surface texture 102B, 162B and/or fine ridges 102A, 162A on the boss cone surface <NUM> and/or on cone surface <NUM> of the sealing insert <NUM>, if desired for certain embodiments. In other embodiments, a satisfactory seal will be obtained with a smooth surface texture 102C, 162C on both the boss cone surface <NUM> and the cone surface <NUM> of the sealing insert <NUM>.

Returning to <FIG>, the boss <NUM> has a generally cylindrical portion <NUM> connected to a shank <NUM>. In the embodiment shown in <FIG>, the shank <NUM> has an outer bearing surface <NUM> and a generally cylindrical shape. The bearing surface <NUM> of the shank <NUM> is located against the outer composite shell <NUM>. The shank <NUM> shown in <FIG> extends along the neck region <NUM> and along a portion of the taper region <NUM> of the liner <NUM>.

The mechanical fastening between the outer composite shell <NUM> and the boss <NUM> is achieved by spikes <NUM> project radially away from the bearing surface <NUM> of the shank <NUM>, as shown in <FIG> and <FIG>. The spikes <NUM> are at least partially embedded in the outer composite shell <NUM> to mechanically fasten the boss <NUM> to the outer composite shell <NUM>. The engagement of the spikes <NUM> with the outer composite shell <NUM> allows the boss <NUM> to oppose the internal pressure and increases the amount of boss torque that can be tolerated without the boss <NUM> separating from the liner <NUM> and/or the outer composite shell <NUM>.

The boss <NUM> optionally includes a flange shoulder <NUM> that is positioned on an outer surface <NUM> of the boss <NUM> between the generally cylindrical portion <NUM> and the shank <NUM>, as shown in <FIG>. The flange shoulder <NUM> contacts the outer composite shell <NUM>. Alternatively, the outer composite shell <NUM> can extend along a portion of the shank <NUM> without abutting a flange shoulder <NUM> on the boss <NUM>.

The liner <NUM> is optionally fabricated with mounting features <NUM> (shown in <FIG>) that aid with positioning and assembly of the boss <NUM> with the liner <NUM>. The liner <NUM> is cut and/or trimmed, if needed, to allow for assembly with the boss <NUM>. After the boss <NUM> and other fittings are assembled with the liner <NUM>, the liner <NUM> and/or the boss <NUM> are optionally heated to cause the liner <NUM> to conform and/or adhere to the boss <NUM>.

After the boss <NUM> and the liner <NUM> are assembled, the liner <NUM> and/or the shank <NUM> can be covered with a resin barrier layer, such as a polymeric film, if desired for a specific application. Additionally, optional breather layers, or a secondary gas barrier layers, can be wrapped around portions and/or the entire length of the liner <NUM> and the shank <NUM>, as desired for specific applications. Suitable materials for the breather layer include woven glass fiber cloth, non-woven glass fiber cloth, and the like. Suitable gas barrier layers include metalized films, EVOH films, and the like.

The outer composite shell <NUM> of the pressure vessel <NUM> is generally formed by disposing resin impregnated fibers <NUM> onto the liner <NUM> after the liner <NUM> and boss <NUM> have been assembled as shown in <FIG> and <FIG>.

A first known method of applying resin impregnated fibers <NUM> to the liner <NUM> is filament winding, and is illustrated in <FIG>. A plurality of fiber filaments <NUM> is grouped to form a fiber strand <NUM>. The plurality of fiber filaments <NUM> can be grouped to form a fiber strand <NUM> before or during a manufacturing process to apply fibers <NUM> to the liner <NUM>. Likewise, a single fiber strand <NUM> or a grouping of a plurality of fiber strands <NUM> can be applied at given time as desired for the manufacturing process. Fiber strands <NUM> can be applied to the liner <NUM> by continuous wrapping one or more fiber strands <NUM> around the liner <NUM> in overlapping helical patterns to form one or more wrapped fiber layers <NUM>, as illustrated in <FIG>. The fiber strands <NUM> can be coated with liquid resin <NUM> prior to being wrapped on the liner <NUM>, as shown in <FIG>. Alternatively, the fiber strands <NUM> can be coated with liquid resin <NUM> after being wrapped on the liner <NUM> and/or the fiber filaments <NUM> can be preimpregnated with resin <NUM>. The resin <NUM> is cured such that the resin <NUM> and wrapped fiber layers <NUM> form a rigid outer composite shell <NUM> surrounding the liner <NUM>.

A second method of applying resin impregnated fibers <NUM> to the liner <NUM> is braiding the fibers <NUM> as illustrated in <FIG>. As with the first method, a plurality of fiber filaments <NUM> is assembled to form a fiber strand <NUM>. A plurality of fiber strands <NUM> are over-braided around the liner <NUM> to form a braided fiber layer <NUM> using a braiding machine <NUM>, as illustrated in <FIG>. Further, the fiber strands <NUM> can be impregnated with resin <NUM> prior to, during, and/or after braiding the fibers strands <NUM> around the liner <NUM>.

Over-braiding a plurality of fiber strands <NUM> around an elongated liner <NUM> using braiding, a process illustrated in <FIG> will form a braided fiber layer <NUM> that conforms to larger diameter cylindrical sections <NUM>, smaller diameter cylindrical sections <NUM>, and tapered transition sections <NUM> of an elongated liner <NUM> for a pressure vessel <NUM>. Likewise, the over-braiding process <NUM> shown in <FIG> can form braided fiber strands <NUM> over the shank <NUM> of the boss <NUM>. The over-braiding process <NUM> is a preferred method of applying resin impregnated fibers <NUM> to conformable pressure vessels <NUM> that can include a plurality of spaced apart larger diameter cylindrical sections <NUM> with adjacent larger diameter sections <NUM> being connected by a smaller diameter cylindrical section <NUM>. When the resin <NUM> is cured, the resin <NUM> and braided fiber strands <NUM> form a rigid outer composite shell <NUM> surrounding the liner <NUM>.

The outer composite shell <NUM>, shown in <FIG>, includes one or more layers of resin impregnated fiber <NUM>. Suitable fibers <NUM> for the outer composite shell <NUM> include one or more of carbon fiber, glass fiber, basalt fiber, boron fiber, aramid fiber, high-density polyethylene fiber (HDPE), Zylon™ poly(p-phenylene-<NUM>,<NUM>-benzobisoxazole fiber (PBO), aramid fiber, Kevlar® poly-paraphenylene terephthalamide fiber, Nylon fiber (PA), polyethylene naphthalate (PEN), polyester fiber (PL), and the like. Suitable resins <NUM> include one or more of epoxy resin, vinylester resin, polyester resin, thermoplastic resins, urethane, and the like.

The selection of materials and dimensions for the liner <NUM>, as well as the type and amount of resin <NUM> and fiber <NUM> forming the outer composite shell <NUM>, are selected based in part on the desired operating conditions of the pressure vessel <NUM>. Further, inclusion of one or more of a breather layer, a barrier layer, and/or a metallic layer between the liner <NUM> and the outer composite shell <NUM>, as well as the material composition of the additional layers, is based in part on the desired operating conditions of the pressure vessel <NUM>.

The outer composite shell <NUM> is formed around an outer periphery <NUM> of the shank <NUM> with the outer composite shell <NUM> abutting the flange shoulder <NUM>, as illustrated in <FIG>. The fiber strands <NUM> are trimmed adjacent the flange shoulder <NUM> to from a composite free edge <NUM>. The flange shoulder <NUM> supports and protects the composite free edge <NUM>. If the boss <NUM> lacks a flange shoulder <NUM>, then the fiber strands <NUM> are trimmed at a predetermined location to form the composite free edge <NUM>. The composite free edge <NUM> can be protected and/or reinforced by applying tape <NUM> covering the flange shoulder <NUM> and the composite free edge <NUM>, as shown in <FIG>. Alternatively, the composite free edge <NUM> near the flange shoulder <NUM> can be covered by additional fiber strands <NUM>, a crimp ring such as a ferrule, or the like. Suitable fibers <NUM> for covering the composite free edge <NUM> include carbon fiber, glass fiber, nylon fiber, and the like. Applying tape, fiber strands <NUM>, and/or a crimp ring over the composite free edge <NUM> can prevent edge delamination, improve pressure vessel <NUM> aesthetics, and/or provide a support area for a pressure vessel <NUM> mount.

Optionally, the inner surface <NUM> of the shank <NUM> can be configured to matingly engage with a tapered section <NUM> of the liner <NUM>, such as illustrated in <FIG> and <FIG>. <FIG> shows a second embodiment of the pressure vessel <NUM> having a boss 16A with a shank 182A that supports the tapered section <NUM> along the entire tapered region <NUM> of the liner <NUM>. Optionally, the boss 16A extends along the tapered section <NUM> all the way past the tapered region <NUM> and overlaps a portion of the larger diameter cylindrical section <NUM> of the liner <NUM>. The shank 182A shown in <FIG> provides full taper anchoring along the tapered section <NUM>. The boss 16A absorbs most of the hoop stress of the liner <NUM> and reduces load on the tapered section <NUM> of the liner <NUM>. The increased contact area between the boss 16A and the liner <NUM> of <FIG> improves the quality of seal. The amount of boss torque that can be tolerated without the boss <NUM> separating from the liner <NUM> and/or the outer composite shell <NUM> is increased by the addition of spikes <NUM> projecting radially from the shank 182A.

In contrast to the embodiments shown in <FIG> and <FIG>, a third embodiment of a boss 16B shown in <FIG> has a shank 182B that supports the tapered section <NUM> along a portion of the tapered region <NUM> of the liner <NUM>. The boss 16B provides partial taper anchoring since the shank 182B only supports a portion of the tapered region <NUM>. The shorter shank 182B shown in <FIG> provides less support for the tapered section <NUM> than the longer shank 182A shown in <FIG>. However, the shorter shank 182B has less material cost than the longer shank 182A. Further, the boss 16B of <FIG> is lighter than the full taper anchoring boss 16A shown in <FIG>. The shape, length, and dimensions of the shank <NUM>, 182A, 182B are selected based in part on the desired operating conditions of the pressure vessel <NUM> as well as secondary factors such as material cost and component weight, and the like.

Turning to <FIG>, spikes <NUM> projecting radially away from the shank <NUM>, 182A, 182B and embedded into the outer composite shell <NUM> mechanically fasten the boss <NUM>, 16A, 16B to the outer composite shell <NUM>. The spikes <NUM> can be distributed over the entire outer bearing surface <NUM> of the shank <NUM>, 182A, 182B. A fourth embodiment is shown in <FIG> of a boss 16C that illustrates alternate placement of the spikes <NUM> on a shank 182C. As illustrated by <FIG>, the spikes <NUM> can be placed in one or more specific zones <NUM>, <NUM>' on the shank 182C. The number, shape, size, and position of the spikes <NUM> attached to the shank <NUM> - 182C are selected based on the expected nominal working pressure or boss torque on the pressure vessel <NUM> during use, the dimensions of the shank <NUM>-182C, the dimensions of the outer composite shell <NUM>, and the like. The spikes <NUM> can be distributed over the entire outer bearing surface <NUM> of the shank 182B or the spikes <NUM> can be placed in specific zones <NUM>, <NUM>' on the shank 182B.

The boss 16C is shown in <FIG> prior to assembly with the pressure vessel <NUM>. The boss 16C has a shank 182C configured to matingly engage with the tapered section <NUM> of the liner <NUM>. Thus, the shank 182C has a tapered conical shape and/or a tapered cylindrical shape that abuts the flange shoulder <NUM>. When the boss 16C is assembled with the liner <NUM> and covered with the outer composite shell <NUM>, spikes <NUM> projecting radially away from the outer bearing surface <NUM> of the shank 182C are embedded into the outer composite shell <NUM> to mechanically fasten the boss 16C to the outer composite shell <NUM>.

Also shown in <FIG> is an optional vent groove <NUM> extending longitudinally along the outer bearing surface <NUM> of the shank 182C and radially along the flange shoulder <NUM>. The boss 16C can include any number and configuration of vent grooves <NUM>, as desired for specific applications, to allow for hydrogen gas venting from the interface between the liner <NUM> and outer composite shell <NUM> to the atmosphere. Gas permeates through the liner <NUM> and collects in a gap between the liner <NUM> and the outer composite shell <NUM>. The permeate gas is vented to atmosphere through the vent groove <NUM> to prevent a subsequent collapse of the liner <NUM>.

In addition, since both the liner <NUM> and the outer composite shell <NUM> are fixedly coupled to the boss <NUM>, as shown in <FIG>, forces applied to the boss <NUM> are distributed to the outer composite shell <NUM>. In contrast, when the boss <NUM> is inserted into an opening in a liner <NUM> that covered with an outer composite shell <NUM> followed by crimping a ferrule around the outer composite shell <NUM>, the boss <NUM> only directly contacts the liner <NUM>. The ferrule is fixedly coupled to the outer composite shell <NUM> and fixedly coupled to the boss <NUM>. However, the boss <NUM> is not directly fixedly coupled to the outer composite shell <NUM>. Instead, the connections between the ferrule and the outer composite shell <NUM> and between the ferrule and the boss <NUM> form the mechanical coupling between the boss <NUM> and the outer composite shell <NUM>. Gaps can form over time between the liner <NUM> and the outer composite shell <NUM>. Further, the ferrule can separate from the outer composite shell <NUM> and/or from the boss <NUM>. Rotational and axial loads on the boss <NUM> can potentially weaken the adhesion of the liner <NUM> to the outer composite shell <NUM>, weaken the ferrule crimp, and/or increase gaps that form between the liner <NUM> and the outer composite shell <NUM>. If the ferrule crimp is loosened sufficiently, then the boss <NUM> can rotate within the ferrule. Movement of the boss <NUM> with respect to the outer composite shell <NUM> due to the weakened ferrule crimp can further cause the boss <NUM> to separate from the liner <NUM>. Replacing the ferrule with the spikes <NUM> on the boss <NUM> directly couples the boss <NUM> to the outer composite shell <NUM> when the spikes <NUM> are embedded into the outer composite shell <NUM>. In some embodiments, the spikes <NUM> can be combined with the ferrule to increase the mechanical coupling between the boss <NUM> and the outer composite shell <NUM>. The inclusion of the spikes <NUM> embedded into the outer composite shell <NUM> can be combined with a number of different fastening methods that attach the boss <NUM> to the liner <NUM> and to the outer composite shell <NUM> if desired and/or required depending on the expected load on the boss <NUM>.

The spikes <NUM> can have various shapes, such as illustrated in <FIG>. Variations in suitable spikes <NUM> include cylindrical-shaped spikes <NUM>, tetrahedron-shaped spikes <NUM>, pyramid-shaped spikes <NUM>, and conical-shaped spikes <NUM>, as non-limiting examples. The tetrahedron-shaped spikes <NUM> have three lateral faces <NUM>. The pyramid-shaped spikes <NUM> have four or more lateral faces <NUM>, including but not limited to five, six, seven, or more lateral faces <NUM>. Each spike <NUM>, <NUM>, <NUM>, <NUM>, <NUM> has a spike main body <NUM> extending between a spike tip <NUM> and a spike base <NUM>. The spike tip <NUM> can be peak-shaped, as illustrated by the pyramid spike <NUM>. Alternatively, the spike tip <NUM> can have a rounded shape, as illustrated by the spike tip <NUM> of the conical spike <NUM>. Any shape of spike <NUM> suitable for an intended application can be used, including a mixture of spike <NUM> shapes and sizes.

The spike base <NUM> can include a cylindrical-shaped pin <NUM> projecting longitudinally away from the spike base <NUM>, as illustrated in <FIG> shows non-limiting embodiments of a cylindrical-shaped spike <NUM>, a tetrahedron-shaped spike <NUM>, a pyramid-shaped spike <NUM>, and a conical-shaped spike <NUM> having a cylindrical-shaped pin <NUM> projecting away from the spike base <NUM>. The pin <NUM> allows for mounting different shaped spikes <NUM>, <NUM>, <NUM>, <NUM>, <NUM> into circular holes <NUM> in the shank <NUM>, as illustrated in <FIG>. The circular holes <NUM> can be recessed cavities, through holes, and/or combinations of cavities and through holes. Further, the pin <NUM> and the holes <NUM> can be non-circular in some embodiments.

<FIG> illustrate methods of attaching the spikes <NUM>, <NUM>, <NUM>, <NUM>, <NUM> to the shank <NUM>. Pressing cylindrical-shaped spike <NUM> into a circular hole <NUM> in the shank <NUM>, as illustrated by arrow D, is shown in <FIG>. The cylindrical-shaped spike <NUM> can be press-fitted (illustrated by arrow D) into a circular hole <NUM> sized to matingly receive the cylindrical-shaped spike <NUM>. The circular hole <NUM> can be a partial depth hole <NUM> or a throughhole <NUM>, as desired for a specific application.

The second attachment method shown in <FIG> is similar to the attachment method shown in <FIG>. The cylindrical-shaped spike <NUM>, the tetrahedron-shaped spike <NUM>, the pyramid-shaped spike <NUM>, and the conical-shaped spike <NUM> can include a cylindrical-shaped pin <NUM> projecting away from spike base <NUM>, as shown in <FIG>. The pin <NUM> is press-fitted (illustrated by arrow E) into a circular hole <NUM> in the shank <NUM> having an inner diameter sized to matingly engage with the pin <NUM>, as shown in <FIG>. The addition of the pin <NUM> to the spike base <NUM> allows for press-fitting non-cylindrical spikes <NUM>, <NUM>, <NUM> to the shank <NUM> using circular holes <NUM>.

Welding the spike <NUM> to the shank <NUM> is a third attachment method illustrated in <FIG>. The spike base <NUM> of each of spikes <NUM>, <NUM>, <NUM>, <NUM>, <NUM> can be welded 286A and/or adhered to the shank <NUM>. <FIG> illustrates welding a spike base <NUM> of a cylindrical-shaped spike <NUM> to the outer bearing surface <NUM> of the shank <NUM>. A weld line 286A is formed around the base <NUM> of the spike <NUM>. While the weld line 286A increases the diameter of the spike <NUM>, it is unlikely to cause problems during the over-braiding process <NUM> since the weld line 286A is adjacent the shank <NUM>. In some embodiments, the spikes <NUM> can be adhered to the shank <NUM> with an adhesive. Welding and adhering attachment methods can accommodate a variety of spike <NUM> shapes, including the cylindrical-shaped spike <NUM>, the tetrahedron-shaped spike <NUM>, the pyramid-shaped spike <NUM>, and the conical-shaped spike <NUM> shown in <FIG>, as well as other shapes of spikes <NUM>.

A fourth method, illustrated in <FIG>, is machining and/or molding the spike <NUM> when the shank <NUM> is formed. The fourth method can be used to form cylindrical-shaped spikes <NUM>, tetrahedron-shaped spikes <NUM>, pyramid-shaped spikes <NUM>, and conical-shaped spikes <NUM>, as non-limiting examples. During a machining process, material is removed around the spike <NUM> to form the spike <NUM>. Alternatively, the spikes <NUM> can be integrated into a molding tool when the boss <NUM> is formed during a molding process.

Referring to <FIG>, a plurality of spikes <NUM> are fixedly coupled to the shank <NUM> of the boss <NUM>. In the embodiment shown in <FIG>, the spikes <NUM> are distributed around the outer periphery <NUM> of the shank <NUM>. The spikes <NUM> can be arranged in a plurality of rows <NUM>, <NUM>' of spikes <NUM> with four rows <NUM>, <NUM>' of spikes <NUM> shown in the exemplary embodiment of <FIG>.

As shown in <FIG>, a row <NUM>, <NUM>' of spikes <NUM> is defined as a plurality of spikes <NUM> spaced around an outer periphery <NUM> of the shank <NUM> wherein the axial distance measured between a terminal end <NUM>' of the boss <NUM> and a center of each spike tip <NUM> within the row <NUM>, <NUM>' of spikes <NUM> is within a range defined by a predefined amount. In one embodiment, the predefined amount may be a multiple of the maximum width <NUM>' of the spikes <NUM> comprising the row <NUM>, <NUM>' of spikes <NUM>, wherein the multiple is <NUM>, <NUM>, <NUM>, or more, as a non-limiting example.

Adjacent rows <NUM>, <NUM>' of spikes <NUM> are spaced apart in an axial direction of the boss <NUM>, as shown in <FIG>. The axial distance 294A between adjacent rows <NUM>, <NUM>' of spikes <NUM> can be uniform between the rows <NUM>, <NUM>' or the spacing can be non-uniform, i.e., some of the rows <NUM>, <NUM>' being spaced closer together than the spacing between other rows <NUM>, <NUM>' of spikes <NUM>.

Further, the spikes <NUM> in a first row <NUM> are aligned in an axial direction of the boss <NUM> with spikes <NUM> in a second row <NUM>' of spikes <NUM> in the embodiment shown in <FIG>. However, it will be understood that any number of spikes <NUM>, any number of rows <NUM>, <NUM>' of spikes <NUM>, as well as relative alignment of spikes <NUM> in a first row <NUM> with respect to the positional alignment of spikes <NUM> in an adjacent row <NUM>', can vary without altering the scope of the invention. Spikes 300A-300D illustrate alternate exemplary spike <NUM> locations on the shank <NUM> of <FIG>. With the inclusion of spikes 300A and 300B, the second row <NUM>' of spikes <NUM> will have more spikes <NUM> than present in the first row <NUM> of spikes <NUM>. Further, spikes 300A and 300B are offset from the spikes <NUM> forming the first row <NUM> of spikes <NUM>. Spikes 300C and 300D are positioned near spike 300E to create a local zone <NUM> with additional spikes 300C-300E. In addition, spikes <NUM> in a first row <NUM> of spikes <NUM> can be circumferentially offset from the spikes <NUM> in an adjacent row <NUM>' of spikes <NUM>, as illustrated in <FIG> described below, if desired for a specific application.

An exemplary arrangement of spikes <NUM> around the outer circumference <NUM> of the shank <NUM> is illustrated in <FIG> is a sectional view of the pressure vessel <NUM> of <FIG> taken along section line A-A. <FIG> shows twelve spikes <NUM> forming a row <NUM> of spikes <NUM> attached to the shank <NUM>. The spikes <NUM> are shown in <FIG> positioned equidistant around the outer periphery <NUM> of the shank <NUM>. However, the spikes <NUM> can be positioned such that the spikes <NUM> are not spaced equidistant around the outer periphery <NUM> of the shank <NUM>. The spikes <NUM> shown in <FIG> are fully embedded into the outer composite shell <NUM>. However, in certain embodiments the spikes <NUM> can be configured to penetrate partially into the outer composite shell <NUM>.

Further, the number of spikes <NUM> can be selected based on the requirements of specific applications. Preferably, the shank <NUM> includes at least four spikes <NUM>. While generally cylindrical-shaped spikes <NUM> are shown in <FIG>, tetrahedron-shaped spikes <NUM>, pyramid-shaped spikes <NUM>, conical-shaped spikes <NUM>, and the like, can be used in place of the cylindrical-shaped spikes <NUM> if desired for a specific application. In addition, the spikes <NUM> can include one or more shapes of spikes <NUM>, i.e., a first portion of the spikes <NUM> can be selected to be cylindrical-shaped spikes <NUM> with the remaining spikes <NUM> being pyramid-shaped spikes <NUM>, as a non-limiting example.

Further, spikes <NUM> can be distributed in one or more local zones <NUM>, <NUM>' on the shank <NUM>, as shown in <FIG>, instead of distributing the spikes <NUM> around the outer periphery <NUM> of the shank <NUM>, as illustrated in <FIG>. Alternatively, the spikes <NUM> can be distributed into two or more local zones <NUM>, <NUM>' on the shank <NUM> wherein the two or more local zones <NUM>, <NUM>' being spaced apart on the outer bearing surface <NUM> of the shank <NUM>. Optionally, the two or more zones <NUM>, <NUM>' can be in selected locations around the outer periphery <NUM> of the shank <NUM>. In addition, the two or more zones <NUM>, <NUM>' can be positioned equidistant apart on the outer periphery <NUM> of the shank <NUM> if desired for a specific application.

Referring to <FIG>, the overall length of the spikes <NUM> can be selected based on the thickness of the outer composite shell <NUM>, the nominal working pressure, or the expected amount of torque on the boss <NUM>, the dimensions of the boss <NUM>, and the number of spikes <NUM> attached to the shank <NUM>. <FIG> show enlarged views of portion C of the pressure vessel <NUM> shown in <FIG> illustrating variations in spike <NUM> length compared to the thickness of outer composite shell <NUM>. Referring to <FIG>, the outer composite shell <NUM> is shown as comprising an exemplary three fiber layers 224A-224C. The spike <NUM> of <FIG> extends through the first fiber layer 224A. In contrast, <FIG> shows the spike <NUM> having a length sufficient to penetrate through all three fiber layers 224A-224C. Various embodiments of the pressure vessel <NUM> can include more or less fiber layers 224A-224C than shown in <FIG>. Thus, the spikes <NUM> can be sized to project into and/or through any desired number of fiber layers 224A-224C, including both braided fiber layers <NUM> and wrapped fiber layers <NUM>. Further, the spikes <NUM> can be embedded in and/or project through supplemental layers of materials between the liner <NUM> and the outer composite shell <NUM>, including barrier layers, breather layers, metallic film layers, and the like.

Referring to <FIG>, the overall shape of the spikes <NUM>, maximum outer diameter <NUM>' of the spikes <NUM>, contour of the spike tips <NUM>, overall height of the spikes <NUM>, circumferential distance between adjacent spikes <NUM>, number of spikes <NUM>, and arrangement of spikes <NUM> on the shank <NUM>, and the like, are selected based in part on the expected rotational and axial forces on the boss <NUM>, the method of applying fiber <NUM> to the liner <NUM>, as well as based in part on dimensions of the shank <NUM>, the outer composite shell <NUM>, and the inclusion of supplemental layers between the liner <NUM> and the outer composite shell <NUM>. For example, a greater number of spikes <NUM> having an increased overall length may be fixedly coupled to the shank <NUM> when elevated rotational and/or axial loads are expected on the boss <NUM> during use. For specific applications with lower expected rotational and axial loads on the boss <NUM>, fewer and/or shorter spikes <NUM> may be selected.

The placement, shape, and overall dimensions of the spikes <NUM> are selected, based in part, on the over-braiding process <NUM> illustrated in <FIG>. A conformable pressure vessel <NUM> is shown in <FIG> having a liner <NUM> with a larger diameter cylindrical section <NUM> that is connected to a smaller diameter cylindrical section <NUM> by a tapered cylindrical section <NUM>. The flare edge <NUM> of the liner <NUM> has been previously fixedly coupled to the bore <NUM> of the boss <NUM> prior to the fibers <NUM> being over-braided around the liner <NUM>. A plurality of fiber filaments <NUM> are grouped into a fiber strand <NUM>. A plurality of fiber strands <NUM> are over-braided around the liner <NUM> using a braiding machine <NUM>, as shown in <FIG>. The braided fiber strands <NUM> conform to the outer surface <NUM> of the liner <NUM> with the density of the braided fiber strands <NUM> on the surface <NUM> of the liner <NUM> changing as the outer diameter of the liner <NUM> varies. The braided fiber strands <NUM> transition smoothly from the liner <NUM> to cover the shank <NUM> without affecting the over-braiding process <NUM>.

The over-braiding process <NUM> can form the braided layer <NUM> of fiber strands <NUM> around the spikes <NUM> projecting from the shank <NUM>, as illustrated in <FIG> and <FIG>. Each of <FIG> and <FIG> show an enlarged view of portion B shown in <FIG>. <FIG> illustrates tetrahedron-shaped spikes <NUM> and <FIG> illustrates cylindrical-shaped spikes <NUM>. Referring to <FIG>, each fiber strand <NUM> comprises a plurality of fiber filaments <NUM>. The exemplary embodiment shown in <FIG> has shank <NUM> outer bearing surface <NUM> diameter of about <NUM>, the fiber strands <NUM> have a nominal strand width <NUM>' of about <NUM>, and the outer composite shell <NUM> comprises a plurality of braided layers <NUM> of fiber strands <NUM> with the outer composite shell <NUM> being about <NUM> in thickness. However, the radial thickness of the outer composite shell <NUM> can be larger or smaller than about <NUM> if desired based on the boss diameter and on requirements of a specific application.

Referring to <FIG>, preferably, the maximum outer diameter <NUM>' of each spike <NUM> is less than the nominal strand width <NUM>' of the fiber strands <NUM> used to form the braided fiber layer <NUM>. More preferably, the maximum outer diameter <NUM>' of the spike main body <NUM> and of the spike tip <NUM> of each spike <NUM> is equal to or less than about half of the nominal strand width <NUM>' of the fiber strands <NUM>. Most preferably, the maximum outer diameter <NUM>' of the spike tip <NUM> and of the spike main body <NUM> of each spike <NUM> is between about <NUM> and about <NUM>. The spike base <NUM> of each spike <NUM> can be larger than the above ranges if desired and further depending on the spike <NUM> attachment method to the shank <NUM>. For example, spikes <NUM> attached to the shank <NUM> may have a flared base 286A larger than the spike main body <NUM> caused by a welding process. For spikes <NUM> having non-cylindrical shapes, such as the tetrahedron-shaped spikes <NUM>, the pyramid-shaped spikes <NUM>, and the like, the maximum outer dimensions <NUM>' of the spike base <NUM> of each spike <NUM>, <NUM>, <NUM> is preferably equal to or less than the nominal strand width <NUM>' of the fiber strands <NUM>, more preferably equal to or less than half the nominal strand width <NUM>' of the fiber strands <NUM>, and most preferably between about <NUM> and about <NUM>. However, spikes <NUM> having larger and/or smaller diameters <NUM>' may be selected for specific applications if desired.

Referring to <FIG>, preferably, the length of each spike <NUM> is between about <NUM> to about <NUM>, as measured between the spike tip <NUM> and the spike base <NUM>. More preferably, the length of each spike <NUM> is sized to at least embed in a first fiber layer 224A that forms the outer composite shell <NUM>, as shown in <FIG>. However, each spike <NUM> can selectively have an overall length sufficient to penetrate any desired number of fiber layers <NUM>, 224A-224C, <NUM>, including both braided fiber layers <NUM> and wrapped fiber layers <NUM>. Further, the length of the spikes <NUM> can be selected to penetrate optional supplemental layers such as one or more of a barrier layer, a breather layer, and the like, if desired for a specific application.

Adjacent spikes 186A, 186B shown in <FIG>, are preferably spaced apart by at least one nominal strand width <NUM>' of the fiber strand <NUM>. The nominal strand width <NUM>' of the fiber strand <NUM> is defined as an approximate width <NUM>' of a fiber strand <NUM>, as illustrated in <FIG>. For the exemplary embodiment shown in <FIG> having a nominal width <NUM>' of fiber strands <NUM> of about <NUM>, the preferred minimum spacing between adjacent spikes <NUM> is at least <NUM>, i.e., the preferred minimum spacing being equal or greater than the nominal strand width <NUM>' of the fiber strands <NUM>. Individual spikes <NUM> can be spaced closer together than the nominal strand width <NUM>' of the fiber strands <NUM> as long as the minimum distance between adjacent spike tips <NUM> is preferably equal or greater than the nominal strand width <NUM>' of the fiber strands <NUM>. The number of spikes <NUM> can be as few as about four with a maximum amount of spikes <NUM> determined by the outer diameter and length of the shank <NUM> while positioning the spikes <NUM> at least a nominal strand width <NUM>' of the fiber strands <NUM> apart. Further, when the boss <NUM> includes a plurality of rows <NUM>, <NUM>' of spikes <NUM>, preferably adjacent rows <NUM>, <NUM>' are spaced at least one nominal strand width <NUM>' of the fiber strands <NUM> apart.

The fiber strands <NUM> are braided around the spikes <NUM>, such as illustrated by relative positions of fiber strands 216A-216D and spike 186A, as shown in <FIG> and <FIG>. When fiber strands <NUM>, 216E align with the spikes <NUM>, such as illustrated by fiber strand 216E and spike 186E shown in <FIG> and <FIG>, some of the fiber filaments <NUM> of the fiber strands 216E will be laid down around the spikes 186E, e.g., the fiber strand 216E is split into groups of filaments <NUM> as illustrated by 214E and 214F. The engagement between the fiber strands 216A-216E and the spikes <NUM>, 186A, 186E interlock the braided fiber layer 224A with the spikes <NUM>, 186A, 186E. Additional braided fiber layers 224B, 224C will interlock with the spikes <NUM>, 186A, 186E in a similar method. Each braided fiber layer 224A-224C that is braided around the spikes <NUM>, 186A, 186E will increase the strength of the mechanical connection between the boss <NUM> and the outer composite shell <NUM>. The mechanical connection between the boss <NUM> and the outer composite shell <NUM> is further strengthened by the curing of the resin <NUM> impregnated into the fiber strands <NUM>, 216A-216E. The fiber strands <NUM>, 216A-216E will be similarly interlocked with the spikes <NUM>, 186A, 186E when the fiber strands <NUM>, 216A-216E are helically wrapped around the shank <NUM> forming wrapped fiber layers <NUM>.

<FIG> illustrate a method of continuous manufacturing of pressure vessels <NUM>, particularly conformable pressure vessels <NUM> with over-braided outer composite shells <NUM>. An exploded view of a liner/boss subassembly <NUM>, <NUM>' is shown in <FIG>. The liner/boss subassembly <NUM>, <NUM>' comprises a liner <NUM>, 14A a boss <NUM>, 16D and a sealing insert <NUM>, <NUM>'. The longitudinal axis of the liner/boss subassembly <NUM>, <NUM>' is shown by element <NUM> in <FIG>. The liner <NUM>, 14A optionally includes a locating feature <NUM> integrated into the cylindrical neck region <NUM> of the liner <NUM>, 14A for locating the boss <NUM>, 16D during assembly. The locating feature <NUM> can include a recessed channel, a ridge, protrusions, and the like as non-limiting examples. The shank <NUM> of the boss <NUM>, 16D is slid over the liner <NUM>, 14A such that the flare edge <NUM> of the liner <NUM>, 14A is inserted into the bore <NUM> of the boss <NUM>, 16D until the terminal end <NUM>' of the boss <NUM>, 16D engages with the locating feature <NUM> on the liner <NUM>, 14A. The sealing insert <NUM>, <NUM>' is assembled with the bore <NUM> of the boss <NUM>, 16D such that the cone surface <NUM> of the sealing insert <NUM>, <NUM>' pinches the liner <NUM>, 14A against the boss cone surface <NUM> of the bore <NUM>. Assembling the boss <NUM>, 16D, the liner <NUM>, 14A and the sealing insert <NUM>, <NUM>' forms the liner/boss subassembly <NUM>, <NUM>' illustrated in <FIG>.

Referring to <FIG>, a liner/boss subassembly <NUM>, <NUM>' is fastened to each terminal end <NUM>, <NUM>' of a sacrificial tubing section <NUM> to form an elongated subassembly <NUM>. The sacrificial tubing section <NUM> is defined by a cylindrical wall <NUM> extending between the opposing terminal ends <NUM>, <NUM>'. Further, the terminal end <NUM> of each boss <NUM>, 16D and the terminal ends <NUM>, <NUM>' of the sacrificial tubing section <NUM> are configured to matingly engage and fixedly couple and/or releasably couple the liner/boss subassemblies <NUM>, <NUM>' to the sacrificial tubing section <NUM>. <FIG> illustrates the elongated subassembly <NUM> of a pair of liner/boss subassemblies <NUM>, <NUM>' coupled to the opposing terminal ends <NUM>, <NUM>' of the sacrificial tubing section <NUM>. Any number of liners/boss subassemblies <NUM>, <NUM>' can be coupled together with sacrificial tubing section <NUM> to form the elongated assembly <NUM> prior to passing the liner/boss subassemblies <NUM>, <NUM>' through one or more braiding machines <NUM>.

<FIG> illustrates a process of feeding the elongated assembly <NUM> through a braiding machine <NUM>, as illustrated by arrow G. Each liner <NUM>, 14A includes one or more larger diameter cylindrical sections <NUM>, smaller diameter cylindrical sections <NUM>, and tapered liner sections <NUM> extending between adjacent larger and smaller diameter sections <NUM>, <NUM>. The braiding machine <NUM> over-braids a plurality of fiber strands <NUM> around the outer periphery <NUM>' of the liner <NUM>, 14A. The braiding process <NUM> automatically braids the fiber strands <NUM> over the outer periphery <NUM>' of the elongated assembly <NUM> with the braided fiber layer <NUM> following the outer contour <NUM>, <NUM>' of the liner <NUM>. As the elongated assembly <NUM> passes through the braiding machine <NUM>, fiber strands <NUM> are braided around the outer periphery <NUM>, <NUM>' of the liner <NUM>, 14A the boss <NUM>, 16D and the sacrificial tubing section <NUM> as these components <NUM>, 14A, <NUM>, 16D, <NUM> pass through the braiding machine <NUM>. The elongated assembly <NUM> can be passed sequentially through a plurality of braiding machines <NUM> with each braiding machine <NUM> configured to over-braid a single layer <NUM> of braided fiber strands <NUM>.

The elongated assembly <NUM> can be wrapped with one or more of barrier layers, breather layers, metallic film layers, and the like, prior to over-braiding fiber strands <NUM> around the elongated assembly <NUM>. Further, one or more of barrier layers, breather layers, metallic film layers, and the like, can be applied to the elongated assembly <NUM> after and/or before over-braiding individual fiber layers <NUM>, 224A-224C. As a non-limiting example, a breather layer can be wrapped around the entire elongated assembly <NUM> prior to over-braiding a first fiber layer <NUM>, 224A around the outer periphery <NUM>' of the elongated assembly <NUM>. As another example, a metallic film layer can be wrapped around the liner <NUM>, 14A around the outer periphery <NUM>' of the first braided fiber layer 224A followed by over-braiding additional fiber layers 224B, 224C around the elongated assembly <NUM>.

<FIG> illustrates the elongated assembly <NUM> after passing through the braiding machine <NUM> and before the braided fiber layer <NUM> is trimmed adjacent the flange shoulder <NUM> of each boss <NUM>, 16D. As shown in <FIG>, the entire elongated assembly <NUM> is over-braided with the fiber strands <NUM>. The braided fiber layer <NUM> is trimmed (as illustrated by arrows K shown in <FIG>) adjacent the flange shoulder <NUM> of each boss <NUM>, 16D to form a composite free edge <NUM>. The sacrificial tubing section <NUM> is removed from each boss <NUM>, 16D after the braided fiber layer <NUM> is trimmed. <FIG> shows the elongated assembly <NUM> after trimming to form separate pressure vessels <NUM>, <NUM>'. The composite free edge <NUM> on each boss <NUM>, 16D can be covered with tape <NUM> and/or a crimped ferrule if desired.

One benefit of a pressure vessel <NUM> having a liner <NUM> fixedly coupled to a boss <NUM> having spikes <NUM> projecting outward from the boss <NUM> embedded in an outer composite shell <NUM> is the boss <NUM> is mechanically coupled directly to the outer composite shell <NUM> as well as mechanically coupled to the liner <NUM>. A second benefit is a seal is achieved between the liner <NUM> and the boss <NUM> by fixedly coupling the liner <NUM> to a boss cone surface <NUM> of a bore <NUM> passing axially through the boss <NUM>. A third benefit is the embedded spikes <NUM> in the outer composite shell <NUM> restrict rotation of the boss <NUM> with respect to the outer composite shell <NUM>. A fourth benefit is the embedded spikes <NUM> in the outer composite shell <NUM> restrict axial motion of the boss <NUM> with respect to the outer composite shell <NUM> since the boss <NUM> and the outer composite shell <NUM> are mechanically coupled by the spikes <NUM>. A fifth benefit is fixedly coupling the liner <NUM> to the boss <NUM> without using a molding process and without using a ferrule to crimp the liner <NUM> to the boss <NUM>. A sixth benefit is fixedly coupling the outer composite shell <NUM> to the boss <NUM> without relying on a ferrule to crimp the outer composite shell <NUM> to the boss <NUM>.

Claim 1:
A pressure vessel (<NUM>) for containing liquids and/or gases under pressure, said pressure vessel (<NUM>) comprising:
a polymeric liner (<NUM>) comprising a hollow body (<NUM>) defined by an elongated cylindrical wall (<NUM>) having opposing inner and outer surfaces extending between a first terminal end (<NUM>) and a second terminal end (<NUM>) of said liner (<NUM>), said liner (<NUM>) including an inlet opening (<NUM>) near said first terminal end (<NUM>) of said liner (<NUM>), said inlet opening (<NUM>) defined by a flare edge (<NUM>) of said liner (<NUM>);
an outer composite shell (<NUM>) comprising resin and fibers, said outer composite shell (<NUM>) surrounding an outer periphery of said liner (<NUM>);
a boss (<NUM>) having a bore (<NUM>) passing axially through said boss (<NUM>), said bore (<NUM>) defined by a cylindrical wall (<NUM>) having an interior surface, said bore (<NUM>) in fluid communication with an interior of said pressure vessel (<NUM>);
said boss (<NUM>) having a shank (<NUM>) with opposing inner and outer bearing surfaces (<NUM>, <NUM>), said inner bearing surface (<NUM>) oriented towards said outer surface of said liner (<NUM>), and said outer bearing surface (<NUM>) oriented towards said outer composite shell (<NUM>);
said shank (<NUM>) including a plurality of spikes (<NUM>) fixedly coupled to said shank (<NUM>) and projecting radially away from said outer bearing surface (<NUM>); and
said flare edge (<NUM>) of said polymeric liner (<NUM>) being fixedly coupled to said boss (<NUM>);
said outer composite shell (<NUM>) is formed by braiding a plurality of fiber strands (<NUM>) around said liner (<NUM>) and said shank (<NUM>) of said boss (<NUM>) to form a layer of braided fiber strands (<NUM>), each of said plurality of spikes (<NUM>) being at least partially embedded into said outer composite shell (<NUM>), wherein each of said plurality of fiber strands (<NUM>) comprises a plurality of fiber filaments (<NUM>), each of said plurality of fiber strands (<NUM>) having a nominal strand width (<NUM>'), and each pair of adjacent spikes (<NUM>) having respective spike tips (<NUM>) being spaced apart by at least said nominal strand width (<NUM>').