A Type V hydrogen storage cylinder structure for aircraft

Abstract

This invention discloses a Type V hydrogen storage cylinder structure for aircraft, comprising an inner metal insert, an outer metal cladding layer, a first carbon fiber composite material layer and a second carbon fiber composite material layer bonded together. The outer metal cladding layer includes a first boss and a first annular post connected to the outside of the first boss. The inner metal insert includes a second boss and a second annular post connected to the outside of the second boss. At the cylinder opening, the inner side of the first boss and the outer side of the first carbon fiber composite material layer, and the inner side of the first carbon fiber composite material layer and the outer side of the second boss are bonded together by heat deformation compensation layers. The second carbon fiber composite material layer is bonded to the inner side of the second boss. The first and second annular posts are interconnected. The design of sandwiching the carbon fiber layer between the inner and outer aluminum alloy metal layers suppresses the thermal mismatch between the carbon fiber cladding layer and the aluminum alloy metal insert under low-temperature and high-pressure cryogenic liquid hydrogen storage conditions.

Description

Technical Field

[0001] This invention relates to the field of hydrogen storage pressure vessel equipment design and manufacturing technology, and in particular to a Type V hydrogen storage cylinder structure for aircraft. Background Technology

[0002] The development and utilization of hydrogen energy mainly involves production, storage, transportation, and use. Among these, hydrogen storage and transportation is one of the most crucial, directly determining the safety and efficiency of hydrogen energy use. Currently, hydrogen storage and transportation technologies primarily include high-pressure gaseous hydrogen storage, cryogenic liquid hydrogen storage, and metal hydride hydrogen storage. Cryogenic liquid hydrogen storage boasts high hydrogen density and energy density, reaching up to 70 kg / m³. 3 It has broad application prospects. Among them, the requirements of low-speed near-space vehicles for long endurance and large payload make the "airborne liquid hydrogen + hydrogen fuel cell" power supply scheme an important research direction.

[0003] Among the various functional components of liquid hydrogen storage, the hydrogen storage cylinder is the most important. The performance of the hydrogen storage cylinder directly affects crucial indicators such as the volumetric density, mass density, cycle life, and safety of the liquid hydrogen storage. Based on the development history of hydrogen storage cylinders and their inner liner materials and winding structures, they can be divided into five main categories. Among them, the linerless hydrogen storage cylinder (Type V cylinder) with full carbon fiber wrapping has advantages such as lightweight design and the absence of inner liner defects, making it a focus of future research.

[0004] In existing technologies, Type V hydrogen storage cylinders lack an inner liner structure in the cylinder body, and a metal frustum structure is still required at the cylinder opening for connection with external pipelines. Furthermore, the cylinder opening is typically designed as an ellipsoid or sphere, making the complex curved surface connection between the carbon fiber composite material and the metal material at the cylinder opening a significant challenge in the design and manufacturing of Type V hydrogen storage cylinders. Moreover, the storage conditions for cryogenic liquid hydrogen in Type V hydrogen storage cylinders are generally 20K and 2MPa. Due to the significant difference in thermodynamic properties between carbon fiber composite materials and metal materials (the coefficient of thermal expansion of aluminum alloy is much greater than that of carbon fiber composite materials), existing cylinder opening structures are prone to excessive shear stress at the connection between the aluminum alloy and carbon fiber composite materials under cryogenic conditions, even leading to delamination, i.e., cryogenic thermal mismatch problems. Therefore, designing a cylinder opening structure and its layered structure suitable for cryogenic and high-pressure conditions for Type V hydrogen storage cylinders is a crucial issue that urgently needs to be addressed in the structural design of Type V hydrogen storage cylinders. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a Type V hydrogen storage cylinder structure for aircraft that features reliable connection, simple processing, and is less prone to thermal mismatch under low temperature and high pressure conditions.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A Type V hydrogen storage cylinder structure for aircraft includes a carbon fiber cylinder body and a metal cylinder mouth. The metal cylinder mouth comprises an inner metal insert and an outer metal cladding layer. The carbon fiber cylinder body comprises a first carbon fiber composite material layer and a second carbon fiber composite material layer bonded together. The outer metal cladding layer comprises a first boss and a first annular post connected to the outside of the first boss. The inner metal insert comprises a second boss and a second annular post connected to the outside of the second boss. At the cylinder mouth, the inner side of the first boss and the outer side of the first carbon fiber composite material layer, and the inner side of the first carbon fiber composite material layer and the outer side of the second boss are bonded together by a heat deformation compensation layer. The second carbon fiber composite material layer is bonded to the inner side of the second boss. The inner side of the first annular post and the outer side of the second annular post are connected together. A through hole is provided at the center of the inner metal insert.

[0008] Furthermore, the heat deformation compensation layer includes several S-shaped aluminum alloy components, which are connected end to end to form an interlocking structure, and the surface of the S-shaped aluminum alloy components is covered with low-temperature resin adhesive.

[0009] Furthermore, the low-temperature resin adhesive is made of 7 wt.% polyethylene glycol modified polyurethane resin.

[0010] Furthermore, a gas barrier resin layer is filled between the first carbon fiber composite material layer and the second carbon fiber composite material layer. The gas barrier resin layer uses epoxy resin mixed with polyethylene as raw material to prevent the hydrogen gas stored in the bottle from leaking through the gap between the inner metal insert and the second carbon fiber composite material layer.

[0011] Furthermore, both the first boss and the second boss are ellipsoidal structures. The longitudinal section of the first boss is an elliptical arc, and the outer longitudinal section of the second boss is an elliptical arc, while the inner section is a vertical line.

[0012] Furthermore, a third annular column is connected to the inner side of the second boss, and a carbon fiber layup mold auxiliary structure is connected to the third annular column.

[0013] Furthermore, the first cylindrical ring and the second cylindrical ring are threaded together, and the third cylindrical ring and the carbon fiber layup mold auxiliary structure are threaded together.

[0014] Furthermore, the first carbon fiber composite material layer is prepared using a carbon fiber winding process, using T1100 carbon fiber as the fiber material and epoxy resin as the resin substrate for layup, with a total of 10 layers.

[0015] Furthermore, the second carbon fiber composite layer is prepared using a carbon fiber winding process, with T1100 carbon fiber as the fiber material and epoxy resin mixed with polyethylene as the resin base for layup, for a total of 6 layers.

[0016] Furthermore, the winding and laying angle of the first carbon fiber composite layer and the second carbon fiber composite layer is ±45° with respect to the horizontal direction.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. The composite laminated structure of the bottle mouth is designed to connect the carbon fiber and aluminum alloy in a composite laminated structure of aluminum alloy-carbon fiber-aluminum alloy. The design of the carbon fiber layer sandwiched between the inner and outer aluminum alloy layers suppresses the thermal mismatch between the carbon fiber coating layer and the aluminum alloy frustum under the low temperature and high pressure of cryogenic liquid hydrogen storage conditions.

[0019] 2. In the two-layer carbon fiber composite material, the inner second carbon fiber composite material layer uses T1100 carbon fiber as the fiber material and epoxy resin mixed with polyethylene as the resin base for layup. The outer first carbon fiber composite material layer uses T1100 carbon fiber as the fiber material and epoxy resin as the resin base for layup. The epoxy resin mixed with polyethylene resin base can improve the gas barrier properties against hydrogen. While maintaining the performance of the original epoxy resin-based carbon fiber composite material, the gas barrier properties of the carbon fiber composite material reinforcement layer against hydrogen are improved, enabling a single carbon fiber composite material layer to meet the strength and gas barrier performance requirements of Type V cylinders.

[0020] 3. The carbon fiber composite layer is bonded to the inner metal insert and the outer metal cladding layer using adhesive. The adhesive material used is 7 wt.% polyethylene glycol-modified polyurethane resin. This 7 wt.% polyethylene glycol-modified polyurethane resin exhibits better tensile strength at low temperatures (70K), further improving the low-temperature connection stability between different material layers in the composite laminate structure of the Type V hydrogen storage cylinder neck. This ensures the reliability of the Type V hydrogen storage cylinder neck composite laminate structure under cryogenic liquid hydrogen storage conditions. Simultaneously, the 7 wt.% polyethylene glycol-modified polyurethane resin adhesive layer acts as a sealant to prevent hydrogen leakage between the carbon fiber composite layer and the inner metal insert and outer metal cladding layer, ensuring the overall airtightness of the cylinder. Attached Figure Description

[0021] Figure 1 This is a perspective view of the structure of the type V hydrogen storage cylinder according to embodiment V of the present invention;

[0022] Figure 2 This is a longitudinal sectional view of a Type V hydrogen storage cylinder structure;

[0023] Figure 3 for Figure 2Enlarged view of a portion of point A in the middle;

[0024] Figure 4 This is a structural diagram of the inner metal insert;

[0025] Figure 5 for Figure 4 BB-direction cross-section;

[0026] Figure 6 This is a structural diagram of the outer metal cladding layer;

[0027] Figure 7 for Figure 6 CC-direction sectional view;

[0028] Figure 8 Structural diagram of a single S-shaped aluminum alloy component;

[0029] Figure 9 This is a schematic diagram of the interlocking structure between S-shaped aluminum alloy components;

[0030] Figure 10 This is a schematic diagram of the first carbon fiber composite layer;

[0031] Figure 11 This is a schematic diagram showing the fiber layup direction of the first carbon fiber composite layer.

[0032] Figure 12 This is a schematic diagram of the second carbon fiber composite layer;

[0033] Figure 13 A cross-sectional view of the auxiliary structure of the carbon fiber layup mold;

[0034] In the figure: 1-First carbon fiber composite material layer, 2-Second carbon fiber composite material layer, 3-First boss, 4-First annular column, 5-Second boss, 6-Second annular column, 7-Heat deformation compensation layer, 8-Through hole, 9-S-shaped aluminum alloy component, 10-Gas barrier resin layer, 11-Third annular column, 12-Auxiliary structure of carbon fiber layup mold, 13-Regular hexagonal column. Detailed Implementation

[0035] To enhance understanding of the present invention, we will now describe it in further detail with reference to the accompanying drawings. These embodiments are for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0036] A specific embodiment of a Type V hydrogen storage cylinder structure for an aircraft, such as... Figure 1-3As shown, the device includes a carbon fiber bottle body and a metal bottle neck. The metal bottle neck is made of aluminum alloy and includes an inner metal insert and an outer metal cladding layer. The carbon fiber bottle body includes a first carbon fiber composite material layer 1 and a second carbon fiber composite material layer 2 that are bonded together. The outer metal cladding layer includes a first boss 3 and a first annular post 4 connected to the outside of the first boss 3. The inner metal insert includes a second boss 5 and a second annular post 6 connected to the outside of the second boss 5. Figure 3 At the bottle mouth, the inner side of the first protrusion 3 and the outer side of the first carbon fiber composite material layer 1, and the inner side of the first carbon fiber composite material layer 1 and the outer side of the second protrusion 5 are bonded to each other by a heat deformation compensation layer 7. The second carbon fiber composite material layer 2 is bonded to the inner side of the second protrusion 5. The inner side of the first cylindrical ring 4 and the outer side of the second cylindrical ring 6 are connected to each other. A through hole 8 is provided in the center of the inner metal insert.

[0037] like Figure 4 , 5 As shown, the inner metal insert is an ellipsoidal second boss 5 with a second annular post 6 and a third annular post 11 connected to its left and right ends, respectively. The second annular post 6 has an inner diameter of 18mm, an outer diameter of 36mm, and a length of 35mm; the third annular post 11 has an inner diameter of 18mm, an outer diameter of 30mm, and a length of 25mm. The left side of the second boss 5 has an elliptical wall with a cross-section of a quarter ellipse with a major axis of 84mm and a minor axis of 42mm. The right side of the second boss 5 is designed as a vertical wall, with the thinnest part of the wall thickness being 4mm. The inner side of the second annular post 6 has an M18×2.0 internal thread for connecting to an external connector with a pipeline, thus forming a gas passage with the external pipeline of the gas cylinder, connecting the gas inside and outside the cylinder. The outer side of the second annular post 6 has an M36×4 external thread for connecting to the outer metal cladding layer. The outer side of the third annular post 11 is designed with an M30×3.5 external thread for connection with the carbon fiber layup mold auxiliary structure 12.

[0038] like Figure 6 , 7 As shown, the outer metal cladding layer is designed as an ellipsoidal first boss 3 connected to a first annular column 4 at its left end, and a regular hexagonal prism 13 is fitted around the outer side of the first annular column 4. The first annular column 4 has an inner diameter of 36 mm, an outer diameter of 42 mm, and a length of 21 mm; the regular hexagonal prism 13 has a side length of 30 mm and a length of 11 mm. The first boss 3 has an ellipsoidal wall structure, with its right-side cross-section being a quarter ellipse with a major axis of 128 mm and a minor axis of 64 mm. The wall thickness of the first boss 3 is 4 mm. The inner side of the first annular column 4 is designed with an M36×4 internal thread for connection with the outer thread of the second annular column 4. The inner wall of the first boss 3 is designed as an elliptical wall with the same curvature as the outer surface of the first carbon fiber composite layer 1, facilitating connection with the first carbon fiber composite layer 1.

[0039] Both the inner metal insert and the outer metal cladding are made of 6061-T6 aluminum alloy and are manufactured by integrated machining. This simplifies the processing steps, optimizes the coaxiality error caused by sectional processing, and eliminates the problem of cylinder mouth failure caused by welding.

[0040] The 6061-T6 aluminum alloy material has good hydrogen permeation resistance and fatigue resistance, which can prevent hydrogen leakage at the mouth of the Type V hydrogen storage cylinder and improve the service life of the Type V hydrogen storage cylinder.

[0041] The heat deformation compensation layer 7 includes several S-shaped aluminum alloy components 9, such as... Figure 8 , 9 As shown, the S-shaped aluminum alloy components 9 are connected end to end to form an interlocking structure. These components are made of 6061-T6 aluminum alloy using a one-piece machining process. Both their inner and outer sides have the same curvature as the attached structure, facilitating connection. This interlocking structure has a circumferential gap. When the aluminum alloy material at the bottle neck shrinks and deforms at low temperatures, the circumferential gap between the two S-shaped aluminum alloy components 9 decreases, preventing direct compression and reducing stress caused by low-temperature deformation of the aluminum alloy.

[0042] Both sides of the S-shaped aluminum alloy component 9 are covered with low-temperature resin adhesive for bonding between the first protrusion 3 and the first carbon fiber composite material layer 1, and between the first carbon fiber composite material layer 1 and the second protrusion 5. The low-temperature resin adhesive uses 7wt.% polyethylene glycol-modified polyurethane resin to improve the shear strength of the bonding surface under low-temperature and high-pressure conditions, ensuring the reliability of the joint connection. The 7wt.% polyethylene glycol-modified polyurethane resin has better tensile strength at low temperatures (70K), which can further improve the connection stability between different material layers of the composite laminate structure at the mouth of the Type V hydrogen storage cylinder at low temperatures. This ensures the reliability of the composite laminate structure at the mouth of the Type V hydrogen storage cylinder under low-temperature liquid hydrogen storage conditions. At the same time, it acts as a sealant to prevent hydrogen leakage between the first carbon fiber composite material layer 1 and the first protrusion 3 and the second protrusion 5, ensuring the overall airtightness of the gas cylinder.

[0043] A gas barrier resin layer 10 is filled between the first carbon fiber composite layer 1 and the second carbon fiber composite layer 2. The gas barrier resin layer 10 uses epoxy resin mixed with polyethylene as the resin material to prevent the stored hydrogen gas from leaking along the gap between the second boss 5 and the second carbon fiber composite layer 2.

[0044] like Figure 10 , 11As shown, the first carbon fiber composite layer 1 is prepared using a carbon fiber winding process. T1100 carbon fiber is used as the fiber material, and epoxy resin is used as the resin substrate for layup, with a total of 10 layers. Specifically, pre-impregnated fiber yarns are wound sequentially into the surface of the second protrusion 5 at alternating layup angles of +45° or -45° to the horizontal direction, for a total of 10 layers. The layup is then completed by curing in a curing oven. The first carbon fiber composite layer 1 uses T1100 carbon fiber as the fiber material and epoxy resin as the resin substrate for layup. Compared to the commonly used T300 and T700 carbon fiber materials, T1100 carbon fiber has better tensile strength. Under the same design strength requirements, it can reduce the number of layup layers and the layup thickness, achieving high-precision layup preparation and lightweight requirements.

[0045] like Figure 12 As shown, the second carbon fiber composite layer 2 is prepared using a carbon fiber winding process. T1100 carbon fiber is used as the fiber material, and epoxy resin mixed with polyethylene is used as the resin base for layup, with a total of 6 layers. Specifically, pre-impregnated fiber yarns are wound sequentially at alternating layup angles of +45° or -45° to the horizontal direction, 6 layers in total, onto the surface of the carbon fiber layup mold. The layup is then completed by curing in a curing oven. The second carbon fiber composite layer 2 uses T1100 carbon fiber as the fiber material and epoxy resin mixed with polyethylene as the resin base for layup. The epoxy resin mixed with polyethylene resin base improves the gas barrier properties against hydrogen. While maintaining the performance of the original epoxy resin-based carbon fiber composite material, the gas barrier properties of the second carbon fiber composite layer 2 are improved, enabling a single layer of carbon fiber composite material to meet the strength and gas barrier performance requirements of a Type V hydrogen storage cylinder.

[0046] The first carbon fiber composite layer 1 and the second carbon fiber composite layer 2 are designed to have the same thickness in the radial direction, which facilitates subsequent layup preparation.

[0047] like Figure 13 As shown, the carbon fiber layup mold auxiliary structure 12 is a ring structure. Its inner side is designed with an M30×3.5 internal thread for connection with the third ring post 11. In the preparation of the Type V hydrogen storage cylinder, a layup mold for the second carbon fiber composite layer 2 is prepared using a soluble material on the carbon fiber layup mold auxiliary structure 12. Then, the carbon fiber layup mold auxiliary structure 12 is combined with the third ring post 11 to complete subsequent processing. By separating the carbon fiber layup mold from the inner metal insert, damage to the inner metal insert during the preparation of the carbon fiber layup mold is reduced. Simultaneously, the design of the third ring post 11 improves the connection strength between the carbon fiber layup mold auxiliary structure 12 and the carbon fiber layup mold.

[0048] Carbon fiber composite layers are prepared using a dry winding process. Dry winding involves directly winding pre-impregnated fiber yarns or tapes onto the surface of a mandrel, or winding fibers softened to a viscous state onto the mandrel surface on a winding machine. Because the pre-impregnated yarns or tapes are professionally manufactured, the resin content (accurate to within 2%) and the amount of pre-impregnated yarn can be strictly controlled. Therefore, the dry winding process allows for precise control of product quality. The biggest advantages of the dry winding process are clean winding equipment, a hygienic processing environment, stable product quality, and winding speeds reaching 100m–200m / min, resulting in high production efficiency. It is suitable for preparing carbon fiber composite layers in the composite laminate structure of Type V hydrogen storage cylinder necks.

[0049] The above specific embodiments are only for illustrating the technical concept and structural features of the present invention, and are intended to enable those skilled in the art to implement them. However, the above content does not limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit and essence of the present invention should fall within the scope of protection of the present invention.

Claims

1. A Type V hydrogen storage cylinder structure for aircraft, comprising a carbon fiber cylinder body and a metal cylinder neck, characterized in that: The metal bottle mouth includes an inner metal insert and an outer metal cladding layer. The carbon fiber bottle body includes a first carbon fiber composite material layer (1) and a second carbon fiber composite material layer (2) that are bonded together. The outer metal cladding layer includes a first boss (3) and a first annular post (4) connected to the outside of the first boss (3). The inner metal insert includes a second boss (5) and a second annular post (6) connected to the outside of the second boss (5). At the bottle mouth, the inner side of the first boss (3) and the outer side of the first carbon fiber composite material layer (1) and the inner side of the first carbon fiber composite material layer (1) and the outer side of the second boss (5) are bonded together by a heat deformation compensation layer (7). The second carbon fiber composite material layer (2) is bonded to the inner side of the second boss (5). The inner side of the first annular post (4) and the outer side of the second annular post (6) are connected to each other. The center of the inner metal insert is provided with a through hole (8). The heat deformation compensation layer (7) includes several S-shaped aluminum alloy components (9), which are connected end to end to form an interlocking structure. The surface of the S-shaped aluminum alloy components (9) is covered with low-temperature resin adhesive. A gas barrier resin layer (10) is filled between the first carbon fiber composite material layer (1) and the second carbon fiber composite material layer (2). The gas barrier resin layer (10) uses epoxy resin mixed with polyethylene as raw material to prevent the hydrogen gas stored in the bottle from leaking through the gap between the inner metal insert and the second carbon fiber composite material layer (2). Both the first boss (3) and the second boss (5) are ellipsoidal structures. The longitudinal section of the first boss (3) is an elliptical arc, and the outer longitudinal section of the second boss (5) is an elliptical arc, while the inner side is a vertical line.

2. The type V hydrogen storage cylinder structure for an aircraft according to claim 1, characterized in that: The low-temperature resin adhesive is made of 7 wt.% polyethylene glycol modified polyurethane resin.

3. The type V hydrogen storage cylinder structure for an aircraft according to claim 1, characterized in that: The inner side of the second boss (5) is connected to a third annular column (11), and the third annular column (11) is connected to a carbon fiber layup mold auxiliary structure (12).

4. The type V hydrogen storage cylinder structure for an aircraft according to claim 3, characterized in that: The first annular column (4) and the second annular column (6) are threaded together, and the third annular column (11) and the carbon fiber layup mold auxiliary structure (12) are threaded together.

5. The type V hydrogen storage cylinder structure for an aircraft according to claim 1, characterized in that: The first carbon fiber composite layer (1) is prepared by carbon fiber winding process, using T1100 carbon fiber as fiber material and epoxy resin as resin substrate for layup, with a total of 10 layers.

6. The type V hydrogen storage cylinder structure for an aircraft according to claim 1, characterized in that: The second carbon fiber composite layer (2) is prepared by carbon fiber winding process, using T1100 carbon fiber as fiber material and epoxy resin mixed with polyethylene as resin base for layering, with a total of 6 layers.

7. A type V hydrogen storage cylinder structure for an aircraft according to claim 5 or 6, characterized in that: The first carbon fiber composite layer (1) and the second carbon fiber composite layer (2) are wound at an angle of ±45° with the horizontal direction.

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