High pressure tank and method thereof

One exemplary embodiment of a high pressure tank and a method thereof includes providing a liner of the high pressure tank. A liner having at least one open end with a first inner diameter and a first outer diameter. The method also including providing a cap having a second outer diameter which is greater than the first inner diameter. The method further includes providing a collar having a second inner diameter which is less than the first outer diameter. The liner is brought to a first temperature, the cap is brought to a second temperature which is less than the first temperature, and the collar is brought to a third temperature which is greater than the first temperature. At least a portion of the cap is placed inside the open end and at least a portion of the collar is placed over the open end.

TECHNICAL FIELD

The field to which the disclosure generally relates includes high pressure tanks, and to methods of assembling high pressure tanks and of assembling ends thereof.

BACKGROUND

High pressure tanks are commonly used to store pressurized gasses and liquids, such as compressed hydrogen, for use in fuel cell vehicles like automobiles. The high pressure tanks can usually handle pressures ranging from vacuum to 10,000 psi and above. Cost and weight are just some of the challenges facing high pressure tanks.

SUMMARY OF EXEMPLARY EMBODIMENTS OF THE INVENTION

One exemplary embodiment includes a method which may include providing a liner of a high pressure tank. The liner having one or more open ends with a first inner diameter and a first outer diameter. The method may also include providing a cap having a second outer diameter which may be greater than the first inner diameter. The method may further include providing a collar having a second inner diameter which may be less than the first outer diameter. The method may include bringing the liner to a first temperature, bringing the cap to a second temperature which may be less than the first temperature, and bringing the collar to a third temperature which may be greater than the first temperature. The method may also include placing a portion or more of the cap inside the open end while the liner is at or near the first temperature and while the cap is at or near the second temperature. The method may further include placing a portion or more of the collar over the open end while the liner is at or near the first temperature and while the collar is at or near the third temperature.

Another exemplary embodiment includes a method which may include forming a liner of a high pressure tank by an extrusion process. The liner may have a first open end and a second open end, and may have a substantially constant inner diameter extending from the first open to the second open end. The method may also include forming a cap. The method may further include forming a collar. The method may include placing a portion or more of the cap inside the first open end, and may include placing a portion or more of the collar over the first open end and over the cap. The method may further include winding a fiber layer over the liner and over the collar from the first open end to the second open end.

Another exemplary embodiment includes a product which itself may include a high pressure tank. The high pressure tank may include a liner, a cap, a collar, and a fiber layer. The liner may have a first open end and a second open end, and may have a substantially constant inner diameter extending from the first open end to the second open end. The cap may be located inside the first open end and may help seal the first open end. The cap may have one or more ribs extending around the cap, protruding from an outer surface of the cap, and abutting the liner when assembled. The collar may be located over the first open end and over the cap to help seal the first open end. And the fiber layer may be located over the liner and over the collar.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description of the embodiment(s) is merely exemplary (illustrative) in nature and is in no way intended to limit the invention, its application, or uses.

The figures illustrate an exemplary embodiment of a high pressure tank10that may be used to store fluids like liquids and pressurized gasses, such as, but not limited to, compressed hydrogen, for use in a fuel cell vehicle like an automobile. The high pressure tank10is designed to reduce manufacturing and assembly costs while maintaining structural integrity and a suitable weight. In one embodiment, the high pressure tank10may include a liner12, an end assembly14, and a fiber layer16.

As an aside, and as used herein, the terms axially, radially, and circumferentially refer to directions relative to the generally cylindrical shape of the high pressure tank10, so that the radial direction extends generally along any one of the imaginary radii of the cylindrical shape, the axial direction is generally parallel to a center axis of the cylindrical shape, and the circumferential direction extends generally along any one of the imaginary circumferences of the cylindrical shape.

The liner12, also called an armature, may serve as a gas and liquid permeation barrier and as a core structural component of the high pressure tank10. Referring toFIGS. 1 and 2, the liner12may have a generally cylindrical shape. In select embodiments, the liner12may be made out of an aluminum, an aluminum alloy, or other suitable material, and may be made by an extrusion process to have a fixed cross-sectional profile throughout its length. Other forming processes may be used in combination with or instead of the extrusion process, including machining processes. The liner12may have a body18defining an interior space20that holds the stored fluid. The body18may extend axially from a first open end22to a second open end24. The liner12may also have a first inner surface26that may contact the stored fluid, and may have a first outer surface28. The fixed cross-sectional profile defines a first inner diameter ID1that may be constant throughout the axial extend of the liner12, so that the measured inner diameter taken at the first and second open ends22,24may be the same as the measured inner diameter taken at about an axial midpoint of the liner. A first outer diameter OD1may also have a constant value throughout the axial extend of the liner12.

The end assembly14may seal the ends of the high pressure tank10against fluid leakage and against exerted forces generated from the stored fluid, if so generated. The end assembly14may close the first open end22, the second open end24, or both open ends. Where only one open end is closed by the end assembly14, another end structure may function as an inlet and/or an outlet for the high pressure tank10and may close the other end. Additionally or instead, the end assembly14may itself incorporate the inlet and/or outlet functions for the high pressure tank10. Referring toFIG. 2, the end assembly14may include a cap30and a collar32.

The cap30may be placed telescopically inside the first open end22to help seal the first open end. The cap30may be inserted entirely within the first open end22(seeFIG. 3), or may be inserted only partly within the first open end. Referring toFIG. 2, the cap30may have a generally disc shape. In select embodiments, the cap30may be made out of an aluminum, an aluminum alloy, or other suitable material, and may be made by a casting process, a forging process, or another forming process that may be used in combination with or instead of the casting and forging processes, including machining processes. The cap30may have a body34which may define a fitting36(shown as an opening) used to install an inlet and/or outlet structure such as a valve, or the body may have a solid one-piece structure without the fitting. The cap30may also have a second outer surface38which may define a second outer diameter OD2. The second outer diameter OD2may have a slightly greater value than the first inner diameter ID1of the liner12. One or more multiple ribs40may protrude radially from the second outer surface38and may extend circumferentially around the second outer surface. In one embodiment, a single rib may span the entire second outer surface38, and may thus constitute the outer surface of the cap30. In the embodiment shown, three ribs40are axially offset from one another and form spaces42between neighboring ribs. Each rib40may define a third outer diameter OD3which may have a slightly greater value than the first inner diameter ID1. In the case where the cap30has the ribs40, the second outer diameter OD2, may have a slightly lesser value than the first inner diameter ID1, while the third outer diameter OD3is still slightly greater in value than the first inner diameter ID1. The exact dimensions of the cap30including the axial thickness, may be dictated by, among other things, the expected forces generated by the stored fluid, if so generated.

The collar32may be placed telescopically over the first open end22to help seal the first open end, and may serve as a pressure ring. The collar32may be inserted entirely over the first open end22(seeFIG. 3), or may be inserted only partly over the first open end. Referring toFIG. 2, the collar32may have a generally ring shape. In select embodiments, the collar32may be made out of an aluminum, an aluminum alloy, or other suitable material, and may be made by an extrusion process, a forging process, or another forming process that may be used in combination with or instead of the extrusion and forging processes, including machining processes. The collar32may have a solid one-piece body44with a third outer surface46and a second inner surface48. The third outer and second inner surfaces46,48may define planar surfaces in the axial direction when viewed in cross-section. The third outer surface46may define a fourth outer diameter OD4, and the second inner surface48may define a second inner diameter ID2which may have a slightly lesser value than the first outer diameter OD1of the liner12. The exact dimensions of the collar32, including the radial width and the axial thickness, may be dictated by, among other things, the dimensions of the cap30and the expected forces generated by the stored fluid and generated by the cap upon assembly.

As mentioned, a second end assembly50may close the second open end24. Referring toFIG. 1, like the end assembly14, the second end assembly50may include a second cap52and a second collar54. The second cap52and the second collar54are similar to the cap30and the collar32, including having the same respective inner and outer diameters, so that a detailed description will not be given here. Moreover, each of the end assemblies may include additional components that have not been shown or described.

The fiber layer16imparts internal pressure resistance to the high pressure tank10, and imparts external damage resistance. The fiber layer16may include carbon fibers, glass fibers, or both, or another suitable composite fiber reinforced material. The fibers may be interwoven with one another and may include a bonding agent such as an epoxy resin. The fiber layer16may be in a pre-peg unidirectional sheet or roll-form. Moreover, the fiber layer16may include one or more layers, including, for example, an intermediate carbon fiber layer and an outer glass fiber layer. Referring toFIG. 1, the fiber layer16may have a third inner surface56and a fourth outer surface58. The exact dimensions of the fiber layer, including the radial width, and the exact material used may be dictated by, among other things, the expected forces generated by the stored fluid, if so generated.

The high pressure tank10may be manufactured and assembled cost effectively. Once the separate components are formed, the end assembly14may be installed in the liner12. In one embodiment, the liner12, the cap30, and the collar32may be brought to a desired temperature before being telescoped together. The exact temperature may depend on, among other things, the material used for the particular component, and the physical expansion or contraction needed for assembly. In one example, the liner12may be heated to a first temperature of about 200-250° C. so that the first inner diameter ID1and the first outer diameter OD1expand in size, or may be left at room temperature (e.g., 25° C. or another value). One example heating process is with an industrial continuous oven where the liner12would be carried on a conveyor, and another example is by induction heating. The cap30and the accompanying ribs40may be cooled to a second temperature below room temperature of about −20 to 10° C., or to about −196° C., so that the third outer diameter OD3of the ribs contracts to a size which is now less than the expanded first inner diameter ID1. One example cooling process is with a cooling bath, such as a liquid nitrogen bath, as the case may be for the latter temperature example. And the collar32may be heated to an elevated third temperature of about 350-400° C. so that the second inner diameter ID2expands to a size greater than the expanded first outer diameter OD1. Again, examples include the industrial continuous oven and the induction heating. In other embodiments, the first, second, and third temperatures may have other values.

While at the first, second, and third temperatures, the liner12, cap30, and collar32can be placed together. Of course, the various components need not be exactly at the first, second, and third temperatures, as the components may begin to change temperature once their particular process is completed; instead, the components may be near their respective temperatures. In one embodiment, a fixture (not shown) may hold and position the components as they are put in place. Because of the physical expansions and contraction, the liner12, cap30, and collar32may be slip-fit together without force and with little or no contact between the components, which may not otherwise be the case. The components may then all be brought to room temperature. In one example, the components are brought to the room temperature by conduction; that is, the cap30may conduct heat from the liner12and from the collar32while the components are at rest. The fixture may still hold and position the components while they are brought to room temperature, and then the fixture may be removed.

Once at room temperature, the various inner and outer diameters may return to their previous sizes. Referring toFIG. 3, the first outer surface28of the liner12may come into direct contact with, and may abut against, the second inner surface48of the collar32. The collar32and the liner12may then exert opposing forces against each other. The outer surface of each rib40may come into direct contact with, and may abut against, the first inner surface26of the liner12. The cap30and the liner12may then exert opposing forces against each other. The ribs40may be embedded in the liner12and may form a respective first, second, and third seal therebetween. The displaced material of the liner12may then fill the spaces42, as the collar32may prevent the material from moving radially outwardly. As an option, a circumferential interface formed between the liner12and the cap30may be welded together to provide an additional seal and an additional way to keep the end assembly14installed in the liner. As a further option, a mechanical fastener may be used with the cap30, collar32, and/or liner12to provide an additional seal and an additional way to keep the end assembly14installed in the liner.

Once installed, the fiber layer16may be wound around the liner12and around the end assembly14. Referring toFIG. 4, a roll60of fiber layer16may be unwound by a winding machine in a high speed process. The fiber layer16may be helically wound over the circumference of the liner12and over the collar32. The third inner surface56of the fiber layer16may directly contact the first outer surface28of the liner12, and may directly contact the third outer surface46of the collar32. The fiber layer16on the roll60may have a pre-sized axial width W that is equal to the axial width of the liner12with the installed end assembly14. After being wound, the fiber layer16may be cured to become permanently adhered to the liner12and to the end assembly14. In one embodiment, an additional and a separate winding process need not be performed over the axially exposed end portion of the end assembly14. In another embodiment, the additional and separate winding process may be performed.

The above description of embodiments of the invention is merely exemplary in nature and, thus, variations thereof are not to be regarded as a departure from the spirit and scope of the invention.