Hydrogen pressure tank comprising thin load-bearing fiber composite shells with H2 barrier layers

Abstract

Hydrogen pressure tank (1) for storing hydrogen, for use in a vehicle, wherein the hydrogen pressure tank (1) is under high pressure during operation, wherein the hydrogen pressure tank (1) has a shell (2) which is composed of several overlapping layers (3), wherein an outer layer (5) has fibers (7) embedded in resin, and an inner layer (6) is designed as a barrier layer (9), wherein several overlapping outer layers (5) with fibers (8) embedded in resin are present in an onion-skin-like manner, the fibers (8) of which are laid down / introduced / oriented in such a way that they are load-bearing when the hydrogen pressure tank (1) is filled, wherein several barrier fiber composite shells, each having a load-bearing fiber composite shell and a hydrogen barrier layer, are arranged one above the other according to the onion-skin principle.wherein, on the one hand, the barrier layer (9) has a PTFE coating or other H2 barrier substance coating on the inside and / or outside, and on the other hand, the resin matrix is ​​covered with H2 barrier particles in the form of graphene particles or platelets.

Description

[0001] The invention relates to a hydrogen pressure tank for storing hydrogen for use in a vehicle, such as a land vehicle, for example a passenger car, a truck or other commercial vehicle, or an aircraft, for example an airplane or a helicopter, wherein the hydrogen pressure tank is under high pressure, i.e., more than 500 kPa, wherein the tank has a shell constructed of several overlapping layers, wherein an outer layer further comprises fibers embedded in resin, for example made of carbon, glass or aramid, wherein the fibers are combined as / into threads, and an inner layer relative to this is designed as a barrier to impeding or preventing the passage of hydrogen. Several overlapping outer layers, arranged like onion skins, are present with fibers embedded in resin, the fibers of which are laid / introduced in such a way that they are load-bearing (all / predominantly, to more than 75%) when the hydrogen tank is filled.

[0002] State of the art includes type 4 CFRP hydrogen pressure tanks with PTFE liners, which are manufactured, for example, using winding technology.

[0003] However, such hydrogen pressure tanks are too heavy and too expensive. Typically, a 4 cm thick wall made of fiber-reinforced composite material, such as CFRP, is used. This material contains only 10% load-bearing fibers. Material efficiency is rather poor. Crash protection is also difficult to implement. Even the 4 cm thick CFRP wall is insufficient. Moreover, it is inefficient and expensive. Furthermore, no thermal protection is included.

[0004] Pressure tanks of this type are also known from DE 10 2015 016 699 A1, DE 10 2015 203 535 A1, DE 10 2016 225 194 A1, DE 20 2015 105 815 U1, US 2018 / 0 356 037 A1, DE 10 2014 016 023 B3, US 2020 / 0 384 719 A1 and US 2013 / 0 313 266 A1, as well as from US 8 074 826 B2, DE 10 2010 033 623 A1, US 2004 / 0 149 759 A1, EP 2 668 019 B1, CN 1 02 332 590 A, US 2018 / 0 100 047 A1 and DE 10 2005 037 636 A1.

[0005] The object of the present invention is to eliminate or at least mitigate these disadvantages.

[0006] This problem is solved according to the invention by the subject matter of claim 1.

[0007] This results in a pressure tank consisting of several material layers with different functions, employing layer-by-layer adapted material systems. In particular, a typically 5 to 10 mm thick PTFE liner is replaced by a thin, load-bearing fiber composite shell (GFRP), each of which is internally lined with H2 barrier layers and / or clad layer by layer, either internally or externally. Several such barrier fiber composite shells are arranged one on top of the other. The onion-skin principle is followed, with a total or individual thickness of 1 to 3 mm being desirable. Using a fiber composite liner as an integrated winding core for the winding process of the actual CFRP pressure tank is advantageous. A winding process has proven particularly effective in manufacturing. Specifically, a hot winding process of approximately...A process temperature of 80 to 120°C is used, which minimizes porosity in the resin matrix thanks to optimized fiber impregnation with low-viscosity resin. A winding pattern with minimal crossovers is achieved, resulting in an extremely dense fiber laminate. In specific cases, a spherical geometry is desirable; this geometry proves superior under load, especially compared to a hollow cylinder or a cylindrical shape. The advantages are particularly evident in aerospace applications, specifically in aircraft.

[0008] As an option, winding without an integrated fiber composite liner should be noted. The use of a salt core coated with an H2 barrier film has proven effective as a core technology. The salt core is then removed after the process, and the barrier layer remains in the tank. The integration of structural foam layers, e.g., made of polymethacrylimide for thermal insulation and, on the outside, as a crash absorber, is advantageous and follows the onion-skin principle, for example. The outer shell can be optimized for crash impact by using thermoplastic fibers. Sensors for tank monitoring, e.g., using strain gauges that are wrapped in the tank, have also proven effective. Applications as high-performance H2 pressure storage with an improved weight-to-volume cost ratio, e.g., in conjunction with a fuel cell drive, for example in aircraft, mini-helicopters, or spacecraft, are being considered.The goal of a 50% reduction in weight and cost compared to today's Type 4 hydrogen pressure tank is achievable.

[0009] Advantageous embodiments are claimed in the dependent claims and are explained in more detail below.

[0010] It is therefore advantageous if the fibers are incorporated into a resin matrix using a (machine-based) winding, laying, weaving, or braiding process. This enables automated, and therefore cost-effective and reproducible, manufacturing.

[0011] The thickness of the shell can be greatly reduced compared to conventional deep-drawn designs if the fibers are incorporated in such a way that they are load-bearing even when the H2 tank is empty (all / predominantly, at least 75%).

[0012] It is advantageous if at least 2, 3, 4, 5, 6, 7, 8, 9 or 10 outer layers are present and at least 2, 3, 4, 5, 6, 7, 8, 9 or 10 inner layers are present.

[0013] If the barrier layer contains glass fibers embedded in a resin matrix and has a PTFE coating or another H2-penetration-inhibiting barrier substance coating on the inside and / or outside, and / or if the resin matrix is ​​permeated with H2 barrier particles, then the H2 storage capacity of the shell is optimized.

[0014] For the future, it is therefore possible that the H2 pressure tank will be designed as a lightweight, safety-critical type 5 hydrogen pressure tank.

[0015] To achieve the goal, it is advantageous if all layers are optimized / designed to meet different requirements. It is beneficial if the innermost layer is optimized for (the lowest possible) H2 permeability, the covering layer is optimized for internal pressure compensation (e.g., through the use of carbon fibers), the covering layer is optimized for external pressure compensation (e.g., through the use of glass and / or aramid fibers), and the outermost layer is optimized for temperature load compensation / thermal insulation.

[0016] It is advantageous if the innermost layer is thinner (but larger than 0.01 mm) than the sum of the outer layers.

[0017] Furthermore, it is advantageous if the inner layer is thinner than the thinnest outer layer, but larger than 0.01 mm.

[0018] An advantageous embodiment is also characterized in that the fiber deposition in one or all layers is carried out in the manner of deposition in a hybrid disc wheel.

[0019] It is advantageous if the hybrid disc wheel has a main body made of fiber composite material, containing at least one load-bearing fiber embedded in a resin matrix or a plurality of such fibers, wherein the main body has a central hub receiving area, wherein the fiber or the plurality of fibers are furthermore formed as a winding thread or as a plurality of winding threads and the winding thread or the plurality of winding threads are laid crosswise on the outside of a fiber composite winding core in such a way that a completely closed hollow disc is formed, leaving the hub area / hub receiving area open.

[0020] It is therefore advantageous if the fiber composite winding core has a core thread or a multitude of core threads embedded in a resin matrix. Such core threads can then be wound onto the core or, alternatively, incorporated via a prepreg design. Fiberglass or carbon fiber threads are particularly suitable as core threads. Blends are also conceivable. Even aramid fibers are a possibility. With such a design, the winding cores required for production can be manufactured in large quantities by machine and kept in stock, or delivered just-in-time to the production line. This enables high cycle times at low costs.

[0021] It has also proven advantageous if the length of the winding thread(s) and / or the core thread(s) is a multiple of the circumference of the main body. Such long or even continuous threads offer advantages in process design compared to short or random threads, although these configurations also offer advantages for certain applications.

[0022] If the core thread(s) on the one hand and the winding thread(s) on the other hand are made of the same material, such as aramid, glass, carbon, or of different materials, such as aramid or glass or carbon in a targeted combination, e.g. glass fibers in the fiber composite winding core and carbon fibers in the thread(s) laid on it, then hybrid disc wheels can be designed to meet specific requirements and adapted to the respective load situation.

[0023] It has proven advantageous if the resin matrix used in the fiber composite winding core and in the main body is of the same type or of different types.

[0024] Different areas of application can be served when the hybrid disc wheel is designed as a machine element disc wheel, car wheel, bicycle (disc) wheel, running wheel, electric vehicle rim, grinding wheel or grinding disc or even a tool or CNC machining machine component.

[0025] Particularly smooth-running hybrid disc wheels can be designed if the main body has a disc-like outer contour with a central through-hole and / or a concave disc contour that becomes thicker or thinner towards the radial outside in the axial direction.

[0026] An advantageous embodiment is further characterized in that a spacer spreads / keeps spaced apart an area closest to the center (in the immediate vicinity of the through-hole or defining / forming it) and a core wall defined by the core thread. Pre-assembled, commercially available bearings can then be easily installed.

[0027] If a hub body is inserted into the spacer (itself), coupling with commercially available bearings can be facilitated.

[0028] It is also advantageous if the spacer is attached to the hub body by force and / or form locking, e.g. glued and / or shrunk on or vice versa.

[0029] Its use as a grinding wheel is particularly advantageous when a separate, circumferential support body is attached to the outer circumference of the main body, which is at least partially covered with an abrasion / wear layer.

[0030] To achieve a particularly smooth and quiet-running device, it is advantageous for the support body to have predefined mounting areas for unbalanced masses, designed for attaching unbalanced masses or individual unbalanced masses. The concept of a separate, circumferential support body attached near or even directly to the outer circumference of the main body, at least partially covered with an abrasion / wear layer, and / or the support body having predefined mounting areas for unbalanced masses, can also be implemented independently of the characteristics of the hybrid disc wheel with a main body made of fiber-reinforced composite material containing at least one load-bearing fiber embedded in a resin matrix, or a multitude of such fibers. Furthermore, it is unnecessary for the main body to have a central hub mounting area.wherein the fiber or the multitude of fibers are formed as a winding thread or as a multitude of winding threads, and wherein it is also dispensable that the winding thread or the multitude of winding threads are laid crosswise on the outside of a fiber composite winding core in such a way that a completely closed concave disk is formed, leaving the hub area / hub receiving area open. This idea can be pursued in a separate patent application, e.g., a divisional application.

[0031] It is of course advantageous if unbalance masses are attached in all unbalance mass mounting areas or at least if unbalance masses are present in selected unbalance mass mounting areas.

[0032] It has proven advantageous if the areas for receiving the balancing weights are designed as radially oriented through holes or blind holes. Inserting the balancing weights is then particularly easy.

[0033] It has proven advantageous for the cross-section of the unbalance mass mounting areas to be circular, elliptical, angular, polygonal, triangular, quadrilateral, trapezoidal, parallelogram-shaped, rectangular, rhomboidal, kite-shaped, or square. The technical effect is particularly pronounced when the unbalance mass is made of or contains metal, such as lead or an iron alloy.

[0034] The costs are reduced if the supporting body is made of or includes (injection-molded) plastic or an iron alloy, such as a steel-chromium-molybdenum alloy.

[0035] If the hub body is designed as a stepped hollow tube, assembly is made easier on the one hand, and the versatile use of different bearings is made possible on the other.

[0036] It has proven advantageous if the hub body has a flange extending radially outwards.

[0037] It is advantageous if the flange rests on the outside of the main body.

[0038] It is also advantageous if there is an extension / bend / kink at the radial end of the flange that extends in the axial direction away from the main body.

[0039] It is particularly preferred if the main body is composed of several wound fiber layers, preferably a first fiber layer closest to the center, a second fiber layer extending radially outwards and partially or completely covering the first fiber layer, and at least a third fiber layer extending radially outwards and partially or completely covering the second fiber layer. The covering is then, for example, end-faced, planar, and ring-shaped.

[0040] It is advantageous if the winding thread or threads have a fundamentally different direction in each of the three fiber layers.

[0041] If the support body has a completely closed or slotted cross-section, e.g., rectangular, it can be easily manufactured from a bent rectangular strip of sheet metal. It is advantageous if the support body is completely or segmentally / sectionally covered on its outer surface, at least on its circumferential surface, with an abrasive layer / substrate, or with a radial thickness of 4.5 mm or less, containing abrasive particles such as diamond chips or corundum particles. The support body itself can also be made of corundum, thus eliminating the need for an additional abrasive layer. These designs offer advantages in the case of unavoidable wear, as the abrasive substrate can then be easily reapplied once it has worn away.

[0042] It is particularly advantageous if the winding thread in the first fiber layer has a Z-orientation or 0°(±5°) orientation.

[0043] It is equally advantageous if the second fiber layer has a Y-orientation or a 45° orientation (±5°).

[0044] Ultimately, it is also advantageous if the third fiber layer has an X-orientation or a 70° orientation (±5°). If the winding thread(s) are deliberately laid / aligned as a tangled thread(s) at the transition from one fiber layer to the next to prevent imbalance, each of the three fiber layers can be created in a single process step. Of course, more or fewer fiber layers are also possible.

[0045] It is advantageous if the inner layer of the barrier layer itself is also composed of several identical or similar layers that completely overlap each other, preferably according to the onion skin principle.

[0046] It is advisable if the total layer thickness is 1 to 3 mm.

[0047] If the inner layer is designed and used as a fiber composite winding core, manufacturing and assembly advantages arise.

[0048] An advantageous embodiment is also characterized in that the thread or threads are arranged radially outside the inner layer forming or encompassing the barrier layer (as far as possible / almost / completely) without crossings or close to crossings.

[0049] For later use, it is advantageous if the shell has an ellipsoidal, convex, spherical or sphere-like geometry / inner / outer contour.

[0050] When graphene particles or sheets are used as the H2 barrier substance, the H2 retention capacity is optimized while reducing manufacturing costs.

[0051] If sensors for temperature and / or voltage measurement are present, e.g., (co-)wrapped, such as strain gauges, the contents of the hydrogen pressure tank can be checked and monitored during operation, which is advantageous for accident-free operation.

[0052] It is also advantageous if thermoplastic fibers are included, preferably in the outermost layer or (also) in other layers. This is particularly beneficial in the case of crash impact.

[0053] The invention also relates to a manufacturing method for a hydrogen pressure tank, preferably of the type according to the invention, wherein a hot winding process is used.

[0054] It is advantageous to maintain a process temperature of 80° to 120°C ±5°C during the hot winding process. Cost and weight advantages are achieved if the fibers used in the hot winding process are pre-impregnated / soaked with resin, or impregnated / soaked with resin during or after winding, preferably using low-viscosity resin.

[0055] It has also proven effective if the layer containing or forming the barrier layer constitutes the fiber composite winding core.

[0056] If the fiber composite winding core is wound onto a expendable core, such as a salt core, or onto a solid core, such as a wooden core, then the fiber composite winding cores can be produced in large quantities by machine and used as needed after intermediate storage. Just-in-time production and deployment are also possible.

[0057] It has also proven effective to use structural foam coatings, for example those containing or consisting of polymethacrylimide.

[0058] The invention is explained in more detail below with the aid of a drawing. The drawing shows: Fig. 1 a perspective view of a hydrogen pressure tank according to the invention with a depicted cutout, Fig. 2 a hydrogen pressure tank according to the invention in a further embodiment in which it takes on the form of a hybrid disc wheel and is manufactured in the manner of a hybrid disc wheel, Fig. 3 an enlargement of area III by the hydrogen pressure tank Fig. 1.

[0059] The figures are purely schematic and serve only to illustrate the invention. Identical elements are identified by the same reference numerals. Features of the individual embodiments are interchangeable.

[0060] In the Fig. Figure 1 shows a hydrogen pressure tank of a first embodiment according to the invention. The hydrogen pressure tank is designated by reference numeral 1.

[0061] Tank 1 has a hull 2. The hull 2 ​​is made up of several overlapping layers 3. Some of these layers are shown as examples in the Fig. 1 with the reference number 3.

[0062] Even the Fig. Section 3 provides further clarification in this regard. For example, the total thickness of the shell 2, designated with reference numeral 4, is 2 cm.

[0063] As in the Fig. As can also be clearly seen in Figure 3, there are, for example, two outer layers 5 and at least one inner layer 6. In these layers 3, especially the outer layer(s) 5 and the inner layer(s) 6, fibers 8 combined to form threads 7 are contained. These threads 7 or fibers 8 in the different layers 3 can be of the same type or different types. An exemplary representation of the same is shown in the Fig. 2 shown.

[0064] Returning to the Fig. 3 is the difference of the inner / innermost layer 6, which acts as a barrier layer 9 to retain H2, can be guessed.

[0065] In the outer layer 5(s), the carbon fibers 7 are stretched. This is implemented in as many of the relevant layers 3 as possible. Reference symbol list 1 hydrogen pressure tank / H2 pressure tank 2 cases 3 layers 4 Total thickness 5 outer position 6 inner layer 7 threads 8 fibers 9 Barrier layer

Claims

[1] Hydrogen pressure tank (1) for storing hydrogen, for use in a vehicle, wherein the hydrogen pressure tank (1) is under high pressure during operation, wherein the hydrogen pressure tank (1) has a shell (2) which is made up of several overlapping layers (3), wherein an outer layer (5) has fibers (7) embedded in resin, and an inner layer (6) is formed as a barrier layer (9), wherein several overlapping outer layers (5) with fibers (8) embedded in resin are present, the fibers (8) of which are laid down / inserted / aligned in such a way that they are load-bearing when the hydrogen pressure tank (1) is filled, wherein several barrier fiber composite shells, each having a load-bearing fiber composite shell and a hydrogen barrier layer, are arranged one above the other according to the onion skin principle,wherein, on the one hand, the barrier layer (9) has a PTFE coating or other H2 barrier substance coating on the inside and / or outside, and on the other hand, the resin matrix is ​​covered with H2 barrier particles in the form of graphene particles or platelets. [2] Hydrogen pressure tank (1) according to claim 1, characterized by , that the fibers (8) are incorporated in a winding-laying, weaving or braiding process and a resin matrix. [3] Hydrogen pressure tank (1) according to claim 1 or 2, characterized by , that the fibers (8) are attached in such a way that they are load-bearing even when the hydrogen pressure tank (1) is empty.

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