Multilayer composite fireproof fast-assembly hydrogen storage cylinder cover

Abstract

The invention belongs to the technical field of hydrogen energy storage and transportation equipment, and particularly discloses a multilayer composite fireproof fast-assembly hydrogen storage cylinder cover which comprises a cover body which extends from a cylinder opening valve seat to a middle straight section and is sleeved with an end seal head, and the cover body is provided with a first port and a second port located at the transition position. An inner-layer bearing shell, an energy-absorbing framework layer, a flame-retardant heat-insulating layer and an outer surface layer are sequentially arranged in the radial direction from inside to outside, and each layer forms a fireproof barrier in a corresponding heated temperature area; the module has the following advantages that the end key area is protected preferentially, heat flux reduction and heat penetration delay are achieved, impact peak clipping vibration suppression is achieved, assembly is quick, disassembly is free of glue, positioning is consistent, modular maintenance is supported, and light-weight integration is considered.

Description

Technical Field

[0001] This invention relates to the field of hydrogen energy storage and transportation equipment technology, and more specifically, to a multi-layer composite fireproof quick-installation hydrogen storage cylinder cover. Background Technology

[0002] In applications such as automotive and low-altitude aircraft, hydrogen storage cylinders, due to their polymer liner and significantly lower temperature resistance limit compared to metals, typically require external protective covers to balance impact resistance and fire insulation. However, these covers suffer from several drawbacks: their fire resistance mechanisms are too simplistic and sensitive to thermal triggering and aging; the carbon layer lacks continuity and durability, making it difficult to effectively reduce heat flux and extend heat penetration time before the polymer liner softens at approximately 200 degrees Celsius; impact energy management lacks tiered energy absorption and deformation tolerance designs, making it difficult to stably clip peaks and suppress local instability under drop or impact spectra; adhesive installation is sensitive to process conditions, with adhesive thickness and curing fluctuations causing layout deviations and assembly stress; replacement requires adhesive removal and cleaning, leading to long downtime and exposure to volatile organic compounds, hindering standardized quick disassembly and modular spare parts rotation; and some thick, heavy-duty materials or metal solutions have high quality and manufacturing complexity, which is detrimental to the integrated application of lightweight platforms and the control of life-cycle costs.

[0003] To address these issues, a multi-layered composite fireproof quick-installation hydrogen storage cylinder cover is proposed. Summary of the Invention

[0004] The present invention aims to provide a multi-layer composite fireproof quick-installation hydrogen storage cylinder cover to solve or improve the shortcomings of existing Class IV hydrogen storage cylinder protective covers in terms of fireproofing, heat insulation, impact energy absorption, and quick installation and maintenance, which make it difficult to simultaneously meet the requirements of high safety and high operation and maintenance efficiency.

[0005] In view of this, a first aspect of the present invention is to provide a multi-layer composite fireproof quick-installation hydrogen storage cylinder cover.

[0006] A second aspect of the present invention is to provide a hydrogen storage cylinder.

[0007] A first aspect of the present invention provides a multi-layer composite fireproof quick-installation hydrogen storage cylinder cover, comprising at least one cover body extending from the cylinder valve seat to a straight section in the middle of the hydrogen storage cylinder and fitted onto the end cap of the hydrogen storage cylinder; the cover body has a first port and a second port formed thereon, the first port surrounding the cylinder valve seat, and the second port surrounding the transition between the straight section in the middle and the end cap; the first port has a snap-fit ​​structure for assembly with the cylinder valve seat; along the radial direction of the hydrogen storage cylinder, the cover body includes a plurality of sequentially arranged hierarchical structures from the inside to the outside, and the plurality of hierarchical structures each having a progressively decreasing heat-receiving zone from the outside to the inside along the radial direction; each hierarchical structure is activated when it is in the corresponding heat-receiving zone to form a fireproof layer that blocks heat from the hydrogen storage cylinder; the fireproof layer formed by each hierarchical structure blocks heat transfer to the hydrogen storage cylinder in different directions.

[0008] A second aspect of the present invention provides a hydrogen storage cylinder, comprising a central straight section, end caps, a cylinder valve seat, and a hydrogen storage cylinder cover as described in any of the above technical solutions; two end caps are provided, and are respectively disposed at the ends of the central straight section; the cylinder valve seat is located at the port of the end cap away from the central straight section; the hydrogen storage cylinder cover includes two covers, and are respectively disposed on the end caps, exposing the central straight section between the two covers.

[0009] The beneficial effects of this invention compared to the prior art are as follows: The multi-layered structure of the cover along the radial direction, together with the fireproof layers formed by each layer within its heating temperature range, creates a thermal resistance network that responds sequentially in time and is superimposed radially, axially, or circumferentially in space. This segmented and peaked heat from external flames and radiation reduces the heat flux entering the bottle per unit time and lengthens the time it takes for the heat front to reach the bottle surface, thus solving the problems of insufficient thermal resistance and rapid penetration of existing single-layer protection.

[0010] Multiple layers are activated at different time series, superimposing to produce stress relief and deformation compliance effects; compared with single material or single mechanism covers, it can better avoid cracking, wrinkling and interlayer delamination caused by abrupt changes in thermal gradient, and improve the geometric stability and durability of the cover-bottle interface.

[0011] The first port is equipped with a snap-fit ​​structure and is assembled with the bottle mouth valve seat to achieve a push-in locking mechanical connection, resulting in a short assembly cycle and high repeatability accuracy. The dual-port geometric reference of the first and second ports ensures clear axial or circumferential positioning of the cover and the bottle, overcoming the problems of positioning drift and rework difficulties in adhesive bonding.

[0012] Additional aspects and advantages of embodiments of the invention will become apparent in the following description or may be learned by practice of embodiments of the invention. Attached Figure Description

[0013] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 The hydrogen storage cylinder of the present invention; Figure 2 This is a schematic diagram of the hydrogen storage cylinder of the present invention cut along the axial direction; Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 for Figure 2 Enlarged view of section B in the middle.

[0014] in, Figures 1-4 The correspondence between the reference numerals and component names in the attached drawings is as follows: 1 Hydrogen storage cylinder, 101 Straight section in the middle, 102 End cap, 103 Bottle neck valve seat, 1031 Annular groove, 104 Transition, 2 Inner bearing shell, 3 Energy-absorbing skeleton layer, 301 Protrusion, 302 Flat surface, 303 Arc-shaped surface, 4 Flame-retardant and heat-insulating layer, 5 Outer layer, 6 Inverted triangular locking block, 7 Connecting edge, 8 Cavity. Detailed Implementation

[0015] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0016] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0017] Please see Figures 1-4 The following describes a multi-layer composite fireproof quick-installation hydrogen storage cylinder cover according to some embodiments of the present invention.

[0018] An embodiment of the first aspect of the present invention provides a multi-layered composite fireproof quick-installation hydrogen storage cylinder cover. In some embodiments of the present invention, such as... Figures 2-4 As shown, the hydrogen storage cylinder cover includes at least one cover body, which extends from the cylinder valve seat 103 of the hydrogen storage cylinder 1 to the straight section 101 in the middle of the hydrogen storage cylinder 1, and is fitted onto the end cap 102 of the hydrogen storage cylinder 1.

[0019] The cover has a first port and a second port. The first port surrounds the valve seat 103 of the hydrogen storage cylinder 1, and the second port surrounds the transition 104 between the middle straight section 101 and the end cap 102. The first port has a snap-fit ​​structure that is assembled with the valve seat 103.

[0020] Along the radial direction of the hydrogen storage cylinder 1, the cover includes multiple sequentially arranged hierarchical structures from the inside to the outside. Each hierarchical structure has a progressively decreasing heat-receiving range from the outside to the inside, so that the outermost layer is set as the most heat-resistant structure and the innermost layer is set as the least heat-resistant structure, and they work together to insulate each other through layer-by-layer barriers.

[0021] Each layer of structure is activated when it is in the corresponding heated zone to form a fireproof layer that blocks heat from the hydrogen storage cylinder 1. The fireproof layer is a change in properties that occurs when heated.

[0022] Each layer of the structure forms a fireproof layer that blocks heat from being transferred to the hydrogen storage cylinder 1 in different directions, so as to maximize the heat insulation effect and deform evenly when heated.

[0023] This invention provides a multi-layered composite fireproof quick-installation hydrogen storage cylinder cover. The cover comprises at least one cover body, which extends spatially from the valve seat 103 of the hydrogen storage cylinder 1 towards the straight section 101 in the middle of the cylinder 1. In the installed state, the cover body completely fits over the end cap 102 of the hydrogen storage cylinder 1, providing tight protection in the weakest end region of the cylinder. Structurally, the cover body has two ports. The first port is used for circumferential engagement with the valve seat 103. This first port not only geometrically surrounds the valve seat 103 but also has a snap-fit ​​structure that engages with it. During actual assembly, this snap-fit ​​structure functions as a push-in locking mechanical connection. When the support shell is forced to cross the valve seat shoulder during assembly, the snap-fit ​​structure undergoes elastic deformation under stress and returns to its original position after passing the limiting ring, thus achieving stable self-locking. This design avoids the uncertainties inherent in traditional adhesive installation, making installation and disassembly standardized and repeatable, which is beneficial for mass production and maintenance. The second port is located in the transition area between the straight section 101 in the middle and the end cap 102. This transition point 104 is often a key location where the stress of the bottle structure transfers from the straight section to the curved surface of the end cap. The cover forms a circumferential fit here, which helps to coordinate and match the mechanical support of the protective layer with the geometric changes of the bottle, avoiding local stress concentration caused by abrupt changes in curvature, thus providing a benchmark for the overall stability of the cover.

[0024] In terms of radial structure, the enclosure is composed of multiple layers from the inside out, forming a composite system with functional division and performance gradient. The layers are arranged according to their temperature resistance, with each layer representing a progressively decreasing temperature range. The outermost layer is designed to withstand the highest heat load, directly resisting external flames and high-temperature radiation; while the innermost layer uses a material with relatively lower temperature resistance, but its geometry is highly consistent with the bottle's shape, serving as a structural load-bearing reference and assembly positioning surface. This gradient arrangement of strong outer and weak inner temperature resistance achieves a progressively activated protective effect from the outside in under fire conditions. The outer layer undergoes physical or chemical transformation under high temperature, forming the first line of insulation. The middle layer material initiates foaming or heat absorption mechanisms in the secondary temperature range, further delaying heat movement. The inner layer maintains a stable shape in the low-temperature range, providing geometric support for the overall enclosure. This weakens the radial heat transfer layer by layer, significantly reducing the heat flux entering the bottle per unit time.

[0025] The multi-layered structure exhibits a layer-by-layer fire barrier effect when heated. The outermost layer preferentially weakens the effect of high-temperature flames, the next outermost layer further extends the heat wave transmission time in a direction different from the outermost layer, and the energy-absorbing skeleton layer and the third inner layer further block and absorb heat in different directions. The inner layers provide assembly references and can degrade after extreme high temperatures to facilitate replacement. The fireproof layers formed by different levels not only block the gradual penetration of heat in the radial direction, but also share the thermal stress in the circumferential and axial directions through the superposition of the thermal deformation characteristics of different materials, thereby avoiding the risk of instability caused by stress concentration in a single layer.

[0026] In summary, this gas cylinder cover adopts a multi-level structure with temperature-differentiated functions and an end-priority coverage arrangement. The cover extends from the valve seat 103 at the cylinder opening along the transition section to the end cap 102, and is positioned and locked at the first port via a snap-fit ​​mechanism. Each level undergoes sequential characteristic changes within different heating temperature ranges and forms a fireproof layer in situ, constituting a composite barrier with sequential temporal response and coordinated radial, axial, and circumferential spatial isolation. The outermost layer preferentially withstands flame and radiant heat, forming a dense or low-thermal-conductivity insulating interface first. The secondary layers then form an insulating body with increasing thickness or significantly decreased thermal conductivity within their respective temperature ranges. The innermost layer provides geometric and assembly references and constrains overall deformation. The thickness gradient and compressible or expandable margins between layers disperse and release thermal stress, thereby suppressing cracking or delamination caused by sudden changes in stress on a single layer. The end-covering strategy directly protects the thermally and mechanically weak points in the transition area between the valve seat and the end cap, and also slows down the migration speed of heat waves from the end to the center, buying time for system depressurization and emergency response. In the event of a collision or drop, the intermediate layer absorbs and passivates the peak impact within the deformation tolerance, reducing the risk of damage to the outer load-bearing structure of the bottle. Under extreme high-temperature conditions, the non-uniform deformation of the inner layer due to the wall thickness gradient causes the locking force of the buckle to decrease in a controllable manner, facilitating quick manual unlocking and replacement after an accident.

[0027] Furthermore, the fireproof layer activated layer by layer in the temperature-divided zones significantly reduces the heat flux entering the bottle per unit time and lengthens the heat penetration path, thus controlling the rate of temperature rise of the inner liner; the snap-fit ​​mechanical connection replaces adhesive, making assembly and disassembly visible, consistent in positioning, and short in cycle time. After an accident, the locking force can be controlled to decrease, making it easy to replace, avoiding the need for adhesive removal and cleaning and exposure of volatile organic compounds; the end-coverage prioritizes the protection of critical risk areas while controlling weight and volume, taking into account the weight balance and layout space of vehicle-mounted and low-altitude platforms, and facilitating standardized mass production and modular spare parts rotation.

[0028] In any of the above embodiments, the hierarchical structure, from the inside to the outside along the radial direction, consists of an inner bearing shell 2, an energy-absorbing skeleton layer 3, a flame-retardant and heat-insulating layer 4, and an outer layer 5.

[0029] From the middle of the end cap 102 towards the straight middle section 101 and the bottle neck valve seat 103, the wall thickness of the energy-absorbing skeleton layer 3 gradually decreases, and a radially outward protrusion 301 is formed. The protrusion 301 can absorb the stress generated by impact and thermal deformation to the greatest extent.

[0030] In this embodiment, the hierarchical structure, radially from the inside out, consists of an inner supporting shell 2, an energy-absorbing skeleton layer 3, a flame-retardant and heat-insulating layer 4, and an outer layer 5. The inner supporting shell 2 uses the high fit between its inner surface and the outer surface of the gas cylinder as a geometric and assembly reference, providing continuous support to the energy-absorbing skeleton layer 3 in both the circumferential and axial directions and limiting its maximum deformation. This ensures that the skeleton layer preferentially undergoes controlled compression rather than disordered bulging under impact or thermal loads. The energy-absorbing skeleton layer 3 extends from the middle of the end cap 102 to the straight section 101 in the middle and the bottle mouth. The wall thickness of the valve seat 103 gradually decreases in the direction of the transition area, and a radially outward protrusion 301 is formed near the transition area. This protrusion 301 achieves local thickness and shape optimization at the geometric inflection point where the curvature of the end cap transitions to the straight section. This allows the skeleton layer to form a progressive energy absorption sequence of first soft and then hard, from thick to thin, and from the center to both sides in the bidirectional force path of the circumferential and axial directions. Thus, under sudden impact, the peak load is dispersed and local instability is suppressed by preferential collapse in the central area, gradual compaction in the transition area, and delayed deformation in the thin-walled area.

[0031] The outer surface of the protrusion 301 can be a flat surface 302 or an arc-shaped surface 303. The flat surface 302 is conducive to forming a surface contact with the flame-retardant and heat-insulating layer 4 to improve the interface shear bearing capacity and the uniformity of the heat conduction path. The arc-shaped surface 303 provides a gradual contact pressure distribution under the coupling effect of thermal expansion and mechanical compression, reducing the risk of interlayer stress concentration and wrinkling. Both improve the stability of the overlay layer under high temperature and impact composite conditions by increasing the effective contact area and compressible margin. The flame-retardant and heat-insulating layer 4 located outside the skeleton layer forms a sandwich structure with thickness buffer and expandable gap under the in-plane support of the skeleton layer and the local support of the protrusion 301. When heated, its thickness increase and porosity change are limited to a controllable range, thereby maintaining the geometric integrity and low thermal conductivity of the continuous carbonized body and avoiding peeling due to the obstruction of free expansion. Under non-fire conditions, this layer, with a smaller initial thickness, together with the outer surface layer 5, provides a low wind resistance and low exposed height envelope. The outermost outer surface layer 5 serves as the overall environmental interface. At room temperature, the surface continuity and certain in-plane stiffness constrain the micro-undulations of the lower layer, so that the flame-retardant heat insulation layer 4 and the energy-absorbing skeleton layer 3 remain stably bonded during transportation vibration and assembly extrusion. In fire or high-temperature radiation conditions, it works with the flame-retardant heat insulation layer 4 to form an outer barrier at the first moment. Its in-plane integrity and the covering effect on the lower layer help to keep the carbonized body of the heat insulation layer from being eroded and destroyed by high-speed airflow and continuously provide a low heat flux path.

[0032] The above four layers form a functional sequence of inner reference, middle energy absorption, outer heat insulation, and surface interface in the radial direction. In the axial direction, relying on the distribution of the skeleton layer wall thickness from the middle of the end cap 102 to both ends and the geometric weighting of the protrusion 301 in the transition area, the impact energy is absorbed in stages and the thermal stress is dispersed and guided. In the circumferential direction, a closed force ring is formed by the continuous support of the bearing shell and the in-plane constraint of the outer surface layer 5. Thus, under conditions such as drop, lateral scraping, or end impact, the reversible or semi-reversible compression energy absorption of the skeleton layer is triggered first, and the bearing shell is delayed to enter the high strain zone. Under the heat deformation, a low thermal conductivity barrier and an expandable buffer are formed from the outside to the inside, which ultimately significantly weakens the heat flux and thermal gradient transmitted to the bearing shell and the surface of the bottle.

[0033] In any of the above embodiments, the outer surface layer 5 includes a silicone rubber coating layer, which is sintered and ceramicized when in the corresponding heated zone, and forms a ceramic barrier along the surface of the central straight section 101.

[0034] In this embodiment, the outer surface layer 5 includes a silicone rubber coating layer. When in normal temperature service, this coating layer forms a continuous and dense surface covering within the range from the bottle neck valve seat 103 to the transition 104, so that the outer surface of the cover forms a complete environmental interface. On the one hand, this interface provides in-plane constraints and shape finishing for the lower layer during assembly and operation, reducing the direct effects of transportation vibration and minor scratches on the lower layer. On the other hand, it establishes stable surface continuity within the surface range of the straight section 101 in the middle of its coverage, reducing the interface non-uniformity caused by curvature changes, thereby providing a geometric and interface basis for the coordinated response in the subsequent heating stage.

[0035] When the silicone rubber coating enters its corresponding heated zone, the coating surface undergoes sintering and ceramization, rapidly transforming into a continuous and dense inorganic ceramic barrier. This ceramic barrier first inhibits the scouring and penetration of high-temperature airflow through surface densification, significantly reducing the intensity of convective heat transfer. Simultaneously, by altering the surface's absorption and reflection characteristics of radiation, it reduces the effective transmission of radiative heat. Combined with the barrier's own low effective thermal conductivity, this constitutes the first line of defense against external heat flow. As ceramization progresses from the surface inward within the heated zone, the barrier can continuously spread axially within the straight section 101 of its covered surface, forming a stable and continuous high-temperature interface. This effectively lengthens the heat transfer path from the outside in and reduces the heat flux transferred to the lower layers per unit time.

[0036] After the ceramic barrier is formed, a functionally complementary interface relationship is established between it and the flame-retardant and heat-insulating layer 4 below it: the dense ceramic body on the outer surface bears the direct impact of high temperature and high-speed airflow, maintaining the geometric integrity of the outer surface; the flame-retardant and heat-insulating layer 4 on the inner side undergoes volume growth and structural changes within its own heated zone, providing thermal resistance and buffering in the thickness direction. The in-plane integrity of the outer layer 5 allows the deformation of the lower layer to unfold within the controlled boundary, reducing the risk of local wrinkling, peeling, and crack propagation caused by restricted free expansion; correspondingly, the support provided by the lower layer in the thickness direction improves the crack resistance stability of the ceramic barrier in sudden high-temperature changes and thermal cycles, so that the two form a stable coupled force and heat transfer network in the radial, axial, and circumferential directions.

[0037] Under combined thermal and mechanical conditions, the ceramic barrier of the outer layer 5, acting as the leading response unit in the time series, preferentially absorbs and weakens external disturbances from flames and radiation. This pre-emptively reduces the heat and stress intensity entering the flame-retardant and heat-insulating layer 4 and the inner layers, thus creating conditions for subsequent layers to function under milder temperature gradients and load conditions. Therefore, without altering the structure and material settings of subsequent layers, the outer layer 5, through its phase change and interface stability within the heated zone, plays a crucial role in initiating the cascade protection mechanism, maintaining the continuity and integrity of the outer surface, reducing the effective intensity of external heat flow, and improving interlayer synergy. Ultimately, it provides the first reliable barrier against heat and external erosion in the central straight section 101 and transition area 104 within its coverage area.

[0038] In any of the above embodiments, the flame-retardant and heat-insulating layer 4 includes an intumescent flame-retardant layer. When the intumescent flame-retardant layer is in the corresponding heated zone, it expands and foams, and forms a low thermal conductivity carbon layer in the radial direction.

[0039] In this embodiment, the flame-retardant and heat-insulating layer 4 includes an intumescent flame-retardant layer, which is applied in a thin layer between the outer surface layer 5 and the inner functional layer during normal temperature service, forming a continuous and uniform intermediate heat insulation layer. This heat insulation layer, even before being heated, provides initial buffering against transient temperature rises due to its inherent low thermal diffusivity; simultaneously, its in-plane continuity provides a stable base for the outer surface layer 5, reducing the impact of micro-undulations on the upper interface and preventing early micro-cracks and wrinkling under transportation vibration and assembly compression conditions. Thus, before entering the heating stage, the flame-retardant and heat-insulating layer 4 serves as a pre-insulating and pre-compliant interface unit, establishing the geometric and adhesion conditions for subsequent thermal and mechanical responses in advance.

[0040] When the intumescent flame-retardant layer enters its corresponding heated zone, foaming and carbonization processes are triggered inside the material, gradually thickening radially and forming a low thermal conductivity carbon layer in situ. This carbon layer consists of multi-scale pores. The stagnant gas in the closed pores significantly inhibits convective heat transfer, the carbonaceous network on the pore walls reduces the effective thermal conductivity, and the combination of pores and walls lengthens the heat penetration path and prolongs the heat diffusion time constant. At the same time, the formation of the carbon layer has a gradient characteristic that advances from the outside to the inside, allowing the high-temperature zone on the outer side to be densified preferentially, while the inner side maintains a relatively high thickness and porosity, thus achieving a thermal resistance gradient of outer density and inner thickness. Through this gradient, the residual heat flux attenuated after the outer layer 5 is secondary peaked here, and the heat flux per unit time transferred to the inner layers is continuously reduced, thereby effectively delaying the advancement of the thermal front.

[0041] In terms of mechanical coordination, the expanded carbon layer possesses both compressibility and in-plane continuity, serving as a compliant buffer between the outer surface layer 5 and the inner functional layer. Its compressibility margin in the thickness direction absorbs some of the interlayer mismatch caused by the temperature gradient, redistributing stress within the carbon layer with a lower peak value and a wider distribution, thus reducing shear concentration at the interface between the outer surface layer 5 and the inner functional layer. Its in-plane continuity maintains synchronous deformation between the upper and lower surfaces, preventing localized bulging and peeling propagation. The dense barrier formed by the outer surface layer 5 at high temperatures acts as an erosion-resistant outer protective surface for the carbon layer, resisting the erosion of high-speed heat flow. Meanwhile, the inner functional layer provides in-plane support, limiting excessive buckling of the carbon layer under pressure, ensuring its geometric integrity and thermal resistance stability during long-term heating, forming a stress chain of outer protection, middle buffer, and inner support.

[0042] Under combined thermal and mechanical conditions, the intumescent flame-retardant layer, as the second response unit in the cascade system, first weakens the flame and radiation in the outermost layer 5 before continuing its operation. Its low thermal conductivity and volume increase in the char layer together construct a thermal resistance barrier in the thickness direction, while its in-plane continuity and compressibility provide interlayer compliance and stress rectification. Thus, the flame-retardant insulation layer 4, on the one hand, extends the time lag before heat reaches the inner layer, and on the other hand, provides a stable, compliant, and intact coupling interface between the upper and lower layers in space, achieving synchronous modulation of heat flow and thermal stress. This creates conditions for the inner layers to function under milder temperature gradients and load conditions, improving the insulation effect at the system level and enhancing the overall structural reliability and durability in extreme environments.

[0043] In any of the above embodiments, a cavity 8 is formed between the inner bearing shell 2, the energy-absorbing skeleton layer 3, and the flame-retardant heat insulation layer 4. The cavity 8 is used to accommodate the expansion of the flame-retardant heat insulation layer 4.

[0044] In this embodiment, the cavity 8 formed between the inner supporting shell 2, the energy-absorbing skeleton layer 3, and the flame-retardant insulation layer 4 is geometrically arranged in a continuous or segmented circumferential pattern. Initially, it is a controlled micro-gap structure designed to provide assembly tolerance absorption and interface decoupling during normal temperature service, while simultaneously reserving volumetric margin for the thickness increase of the flame-retardant insulation layer 4 during heating. The presence of the cavity 8 prevents a rigid bonding relationship between the three components: the inner supporting shell 2 maintains its fit and assembly reference to the bottle body, the energy-absorbing skeleton layer 3 bears the impact and deformation tolerance at normal temperature, and the flame-retardant insulation layer 4 is positioned between the two with a smaller initial thickness. By matching the circumferential continuity and axial coverage of the cavity 8 with the curvature and load distribution of the end cap 102 and the transition section, sufficient thickness-to-weight movement space can be obtained without increasing the external envelope, avoiding localized stress concentration and early delamination caused by geometrical abrupt changes.

[0045] When the heating phase begins, the flame-retardant and heat-insulating layer 4 initiates its expansion and foaming process after reaching its corresponding temperature range. The cavity 8 then serves as the available expansion volume in response: the expansion layer first grows freely into the cavity 8 until it contacts the adjacent layer, at which point it enters a restricted expansion state. This growth path, consisting of two stages—free growth and restricted filling—gradually releases the expansion pressure, preventing steep peak stresses at the interlayer interfaces. The resulting low thermal conductivity carbon layer maintains continuity and integrity in the thickness direction. The volume margin of the cavity 8 ensures a controllable gradient of porosity and the ratio of dense to loose areas along the thickness of the carbon layer, thereby lengthening the heat penetration path, reducing the heat flux per unit time, and suppressing wrinkling, bulging, or localized peeling caused by excessive restriction. Simultaneously, the cavity 8 provides a uniform clearance zone in the circumferential direction, resulting in better consistency in the expansion of the carbon layer along the bottle's circumference, avoiding asymmetric deformation and heat leakage channels caused by localized jamming.

[0046] Cavity 8 also serves as a layer conformity and stress rectification mechanism. Its thickness compressibility margin and perimeter slip freedom allow external heat flow and mechanical disturbances to undergo a thickness-wise absorption and in-plane diffusion energy redistribution before passing through the flame-retardant insulation layer 4 and the energy-absorbing skeleton layer 3 to the inner supporting shell 2. This not only reduces the interfacial shear peak but also decreases the tendency for interfacial peeling caused by thermal mismatch due to temperature gradients. The controlled compression of the energy-absorbing skeleton layer 3 during impact can temporarily occupy part of the volume of cavity 8. However, since cavity 8 is arranged in a continuous circumferential or segmented manner, its recovery path is unobstructed. After unloading, it can rebound together with the skeleton layer, maintaining interfacial spacing and subsequent volume redundancy under heat, thus achieving compatibility and connection between impact energy absorption and thermal expansion clearance functions on the time axis.

[0047] To improve long-term service stability and predictability of accident conditions, cavity 8 can be equipped with controlled exhaust microchannels or slow-release gaps without compromising overall sealing. This allows the gas generated during expansion and the entrained low-velocity hot gas to migrate slowly along the thickness or circumferential direction, preventing the formation of high-pressure bubbles that could rupture the carbon layer. Alternatively, the equivalent volume and shape of cavity 8 can be regionalized through circumferential segmentation, axial partitioning, or local height restriction. This ensures that the expansion layer receives priority volume allocation in critical areas while being restricted in secondary areas, thus aligning the expansion thickness and thermal resistance gain with the most needed heat flow path. At room temperature, cavity 8 can also accommodate assembly tolerances and adapt to microscale morphology, reducing initial prestress caused by manufacturing and installation errors. During temperature cycling, the deformation library provided by cavity 8 transforms repeated thermal expansion and contraction between layers into a low-peak, wide-cycle stress history, delaying the initiation and propagation of fatigue cracks and improving durability.

[0048] In any of the above embodiments, the energy-absorbing skeleton layer 3 includes a flame-retardant modified foamed polypropylene layer. When the flame-retardant modified foamed polypropylene layer is in the corresponding set heating zone, the embedded energy storage filler absorbs heat from the inside of the flame-retardant modified foamed polypropylene layer.

[0049] In this embodiment, the energy-absorbing skeleton layer 3 includes a flame-retardant modified foamed polypropylene layer, located between the inner supporting shell 2 and the flame-retardant heat insulation layer 4. Structurally and functionally, it undertakes a composite function of load-bearing support, energy absorption, and thermal buffering. This foamed layer has a closed-cell multi-cell structure, with the cell walls and bead fusion interfaces forming a three-dimensional stress network. Under normal temperature and moderate strain rates, it exhibits significant hysteresis characteristics and a plateau yield segment: external impact or drop loads are first dispersed to a large number of cells, and the deformation path gradually unfolds within the layer in a manner of initial local collapse followed by regional expansion, transforming the instantaneous peak value into an equivalent load over a longer time scale, thereby reducing the peak stress transmitted to the inner supporting shell 2 and the bottle surface. Because it is a closed-cell system, the air within the layer provides a gas spring effect during compression, allowing it to partially return to its original shape after unloading. This balances one-time energy absorption with limited shape recovery capability, enabling the cover to maintain stable fit and appearance integrity under low- and medium-intensity scenarios such as transportation vibration and assembly compression.

[0050] Under thermal conditions, when the flame-retardant modified foamed polypropylene layer enters its corresponding set heating temperature range, the pre-embedded energy storage filler absorbs heat from within the material and undergoes phase or microstructural transformation, significantly increasing the local equivalent heat capacity and thermal inertia through latent or sensible heat, thus delaying the advancement of the heat wave in the thickness direction and the arrival time of the temperature peak. At this time, the flame-retardant modification of the foamed polypropylene matrix inhibits dripping and open flames, maintains the geometric continuity and load-bearing channels of the foam skeleton, and allows the heat absorption behavior to proceed under the premise of structural stability. The dispersed embedding of the energy storage filler allows heat to be redistributed within the layer through multi-point absorption and multi-path diffusion, reducing the thermal gradient and thermal stress concentration on a single interface. In conjunction with the flame-retardant heat insulation layer 4 on its outer side, the low thermal conductivity carbon layer generated by the expansion of the outer layer is responsible for weakening the instantaneous heat flux density, while the energy-absorbing skeleton layer 3 further delays the heat front by increasing the equivalent heat capacity and extending the time constant, making the temperature rise process to the inner load-bearing shell 2 more gradual, ensuring that the inner liner of the bottle is in a safe temperature range within the critical time window.

[0051] The energy-absorbing skeleton layer 3 serves as both a compliant core layer between the upper and lower layers and a rectifier against interlayer shear and delamination risks. When external thermal expansion and internal pressure are superimposed, the skeleton layer, through its thickness compressible margin and in-plane continuous support, transforms the peak shear caused by interlayer mismatch into a wider-distributed low-peak stress field. The gradient unfolding of cell collapse allows for temporal release of the interface, preventing local bulging or wrinkling due to restricted free expansion, and reducing the tendency for delamination between the outer layer 5 or the insulation layer and the skeleton layer. The skeleton layer provides in-plane support and thickness buffering for the inner load-bearing shell 2, limiting the latter's high-amplitude vibration and displacement accumulation during thermal cycling, maintaining the geometric reference and positioning accuracy of the interface between the cover and the bottle, and improving the coordinated stability of the multilayer structure in the radial, axial, and circumferential dimensions at the system level.

[0052] In any of the above embodiments, the inner bearing shell 2 includes an engineering plastic layer, with the first port and the second port located at the ends of the engineering plastic layer, respectively; the wall thickness of the engineering plastic layer gradually increases from the second port to the first port.

[0053] When the engineering plastic layer is in the corresponding heating zone, the stress acting on the snap-fit ​​structure is adjusted along the direction of increasing wall thickness.

[0054] In this embodiment, the inner supporting shell 2 includes an engineering plastic layer. A first port and a second port are respectively located at both ends of this engineering plastic layer, forming a stable geometric reference and assembly boundary with the outer surface of the gas cylinder in the installed state. The inner surface of the engineering plastic layer achieves high adhesion with the straight section 101 in the middle of the cylinder and the end transition area at room temperature, thereby limiting the allowable deformation of the cover in the radial and axial directions and providing a continuous and flat base for the laying of the outer functional layers. The wall thickness of the engineering plastic layer gradually increases from the second port to the first port, forming a thickness gradient along the axial direction: the thinner area near the second port balances lightweight design and conformability, facilitating curvature adaptation in the transition area; the thicker area near the first port is used to bear the assembly compression, engagement reaction force, and service load of the snap-fit ​​area, thereby maintaining reliable locking and dimensional stability under normal temperature and moderate impact conditions.

[0055] This thickness gradient also plays a crucial role in the assembly process, acting as a guide, bridging, and return mechanism: as the cover is advanced along the cylinder's axial direction, the thinner section, with its higher geometrical flexibility, can absorb assembly interference caused by the shoulder and limiting ring; as it advances to the first port, the thicker section provides support for the snap-fit ​​structure with higher out-of-plane stiffness, allowing the snap-fit ​​block to quickly return to its original position after crossing the shoulder and establishing sufficient engagement depth and normal contact pressure, ensuring the repeatability and consistency of the push-in-lock action. Thus, the engineering plastic layer balances assembly accessibility and service stiffness during normal temperature service: the thinner section provides compliance and tolerance absorption, while the thicker section provides load-bearing capacity and positioning; the two achieve shock-free force transfer through a continuous thickness transition, avoiding localized stress concentration.

[0056] When the engineering plastic layer enters its designated heating zone, the material's elastic modulus and yield strength decrease with increasing temperature. Differences in thermal expansion and softening caused by uneven thickness result in non-uniform shrinkage and bending forces within the layer. These forces drive stress redistribution along the thin-to-thick direction: thinner areas soften faster due to heat, releasing constraints and undergoing greater deformation first; while thicker areas maintain relative geometric integrity after heating, the contact pressure and shear stress vector between them and the snap-fit ​​seat change direction and magnitude with temperature evolution. Specifically, the resultant force acting on the snap-fit ​​structure gradually decreases along the increasing wall thickness direction, with the normal component decreasing in proportion and the tangential component tending to homogenize, thus causing a controllable decrease in the locking force and pull-out resistance at the engagement interface. This stress adjustment along the thickness gradient is not an instantaneous failure, but occurs gradually with temperature and time: in the initial stage, the contact pressure mainly decreases; in the middle stage, local creep and relaxation are the main features; and in the final stage, the contact area and friction factor are reduced in combination. Finally, when the accident is handled, the system temperature drops, and the unloading conditions are met, the latch can easily disengage.

[0057] In any of the above embodiments, the snap-fit ​​structure includes: The inverted triangular locking block 6 engages with the annular locking groove 1031 on the bottle neck valve seat 103.

[0058] Connecting edge 7 is used to connect the inverted triangular card block 6 and the engineering plastic layer.

[0059] In this embodiment, a snap-fit ​​structure is located at the first port, comprising a self-locking unit consisting of an inverted triangular snap-fit ​​block 6 and a connecting edge 7. The inverted triangular snap-fit ​​block 6 is arranged axially, and its outline is wedge-shaped in both radial and axial sections. The outer surface of the wedge is used to form a guiding contact with the outer edge of the bottle neck valve seat 103 and the entrance of its annular groove 1031 during assembly and advancement. The inner surface of the wedge is used to form a main pressure-bearing fit with the bearing shoulder of the annular groove 1031 after positioning, thereby providing a reliable anti-reverse action on the cover in the axial direction. The annular groove 1031 is a continuous circumferential recess on the outer periphery of the valve seat. After the snap-fit ​​block enters the groove, it forms a circumferentially closed mechanical restraint, avoiding high stress areas caused by local point contact, and ensuring that the anti-reverse force is evenly distributed along the circumferential direction. The connecting edge 7 is located between the card block and the engineering plastic layer, serving as a bridging unit for load transfer and deformation transition: one end is connected to the root of the card block, and the other end is integrally formed with the thick area of ​​the engineering plastic layer, creating a continuous material and geometric transition. This ensures both elastic clearance during assembly and provides sufficient back support stiffness and pull-out resistance for the card block after locking.

[0060] During assembly, the cover is pushed in along the cylinder axis. The inverted triangular locking block 6 first contacts the valve seat shoulder or the slot inlet. Through wedge geometry, the axial thrust is converted into a local radial outward expansion force, causing the connecting edge 7 and its connected engineering plastic layer to undergo controlled elastic deflection and slight radial opening in a local area, thus achieving the crossing of the valve seat shoulder. When the maximum thickness of the locking block passes through the shoulder and enters the annular slot 1031, the elastic energy of the connecting edge 7 and the engineering plastic layer is released, and the locking block rebounds in the opposite direction. Its holding surface and the slot bearing shoulder form a surface contact or near-surface contact fit, establishing sufficient normal contact pressure and circumferential friction fit. At this time, the axial outward pull force is offset by the normal reaction force of the locking block holding surface and the slot bearing shoulder, and the radial inward force is transmitted to the thick area of ​​the engineering plastic layer through the connecting edge 7, forming a continuous force flow of wedge bearing pressure, connecting edge 7 transmitting force, and thick area back support. Since the annular groove 1031 provides a circumferentially distributed constraint, the cyclic load caused by road vibration, pressure pulsation or slight end collision after assembly is averaged in the circumferential direction, reducing the fatigue accumulation in a certain isolated direction.

[0061] During service, the self-locking characteristic of the snap-fit ​​structure originates from the geometric relationship and interface friction between the wedge retaining surface and the bearing shoulder of the slot: under normal temperature and load, the angle between the retaining surface and the axial direction is within the self-locking range, and the interface normal pressure and friction together provide anti-pull-out capability; the bending and tensile coupling stiffness of the connecting edge 7 ensures that the wedge can maintain its fit under small displacement disturbances, without significant loosening or engagement jumps. When encountering impact conditions, the peak axial impact is decomposed into radial and circumferential components through the retaining surface. The radial component is absorbed by the connecting edge 7 and the thick back support, while the circumferential component diffuses along the circumference of the slot, thereby achieving passivation and redistribution of the peak load. When the ambient temperature rises and enters the heated zone of the engineering plastic layer, the elastic modulus and yield strength of the engineering plastic layer decrease. Furthermore, the difference in thermal softening caused by the gradual increase in wall thickness from the second port to the first port leads to a directional stress redistribution in the connecting edge 7 and the thick-area system. On the one hand, the normal contact pressure on the retaining surface of the locking block gradually decreases over time and temperature, reducing the contribution of interfacial friction. On the other hand, the bending internal force and return torque of the connecting edge 7 decrease synchronously, causing a decrease in the resultant resistance of the locking block in the outward pull direction. This stress adjustment along the direction of increasing wall thickness allows the locking force of the buckle to decrease controllably after high-temperature extreme conditions, ensuring reliable locking before an accident and providing a low-damage mechanical channel for manual unlocking and cover replacement after an accident.

[0062] In any of the above embodiments, the protrusion 301 is formed with a flat surface 302 and an arc-shaped surface 303, and the flame-retardant heat insulation layer 4 and the outer surface layer 5 extend along the flat surface 302 and / or the arc-shaped surface 303, respectively.

[0063] In this embodiment, when the protrusion 301 absorbs the geometric changes from the end cap 102 to the transition area, it forms two types of external geometry: a flat surface 302 and an arc-shaped surface 303. This allows the overlying flame-retardant and heat-insulating layer 4 and the outer surface layer 5 to adhere, extend, and transition continuously along these surfaces. By providing differentiated load-bearing shapes at the same circumferential position, the protrusion 301 provides a stable and predictable laying base for the overlying layer. On the other hand, it resolves the interface inhomogeneity caused by curvature changes and thickness gradients in both axial and radial dimensions, thereby enabling the overlying layer to achieve a continuous, dense, and thickness-controllable coverage over a large area.

[0064] When the protrusion 301 adopts a flat surface 302, the overlying flame-retardant and heat-insulating layer 4 and the outer surface layer 5 achieve near-ideal surface and surface contact conditions: the laying thickness is easier to maintain uniformity, the in-plane stress distribution is more balanced, and the interface shear is averaged along the circumferential and axial directions, which helps to suppress local wrinkling and ripples in the initial application stage. The flat surface 302 also facilitates precise thickness control and dimensional reproduction in manufacturing and assembly, enabling the overlying layer to maintain stable adhesion under conditions such as normal temperature vibration and slight compression; after entering the heating stage, the flame-retardant and heat-insulating layer 4 can expand on the flat substrate in an approximately uniform thickness manner as the thickness increases with temperature, reducing heat flow short circuits and thermal gradient peaks caused by local step effects. The outer surface layer 5 is also easier to maintain surface integrity and in-plane constraint on the underlying layer due to its better in-plane continuity.

[0065] When the protrusion 301 adopts an arc-shaped surface 303, its continuous curvature provides a geometric buffer zone for the overcoat layer. At locations where curvature changes abruptly, such as the transition zone between the straight section and the end cap, the arc-shaped surface 303 guides the overcoat layer to smoothly flare and transition along the axial and circumferential directions through a gradual curvature, significantly reducing stress concentration and edge warping tendency at the interface. Under heated conditions, the thickness of the flame-retardant and heat-insulating layer 4 increases outward and gradually under the guidance of the arc-shaped surface 303, avoiding localized restricted expansion and bulging at sharp edges or corners, thus making it easier to form a continuous, low thermal conductivity thickness barrier. In conjunction with this, the in-plane stretching of the outer surface layer 5 along the arc-shaped surface 303 is more gentle, and the stress distribution at the interface during thermal cycling is more uniform, which can delay the initiation of fatigue cracks and improve cycle durability.

[0066] In the scenario where the flat surface 302 and the curved surface 303 work together, the flame-retardant heat insulation layer 4 and the outer surface layer 5 can be extended along a single geometry according to functional areas, or continuously laid out along the same circumferential path in a pattern of first curved and then flat, or first flat and then curved. The curved surface 303 undertakes the curvature transition and stress rectification, so that the upper cover layer maintains fit and thickness continuity when crossing the geometric change area. After entering the flat surface 302, the upper cover layer extends stably with equal thickness, further consolidating the in-plane integrity and thickness control accuracy. The spatial coupling of the two geometries enables the upper cover layer to achieve continuous effects of compliant transition, uniform load-bearing, and controllable thickening in the three stages of laying, service, and heating, respectively: wrinkling and edge lifting are reduced in the laying stage, circumferential and axial loads are evenly distributed in the service stage, and morphological constraints are provided for thickness growth and surface integrity in the heating stage. Finally, without increasing the outer envelope, the coordinated modulation of the heat flow path and interface stress is achieved, ensuring that the flame-retardant heat insulation layer 4 and the outer surface layer 5 maintain a continuous, dense, and stable protective form in key areas.

[0067] Specifically, the specific parameters of each hierarchical structure of the present invention are as follows: The outermost layer 5 has a thickness ranging from 0.5 to 1.5 mm, preferably about 0.8 mm, and can maintain continuous coverage when the ambient temperature rises to 300°C to 400°C. It does not melt or drip under high temperature conditions of 600°C to 800°C, and the surface integrity is maintained for no less than 15 minutes. It is used as the outermost first heat insulation barrier.

[0068] The thickness of the flame-retardant heat insulation layer 4 ranges from 1.0 to 2.0 mm, preferably about 1.2 mm. It triggers volume expansion in the temperature range of 180℃ to 250℃, with an expansion ratio of 2 to 5 times the original thickness. The thermal conductivity of the expanded carbon layer is not greater than 0.1 W / (m·K). It can maintain continuous heat insulation for no less than 20 minutes at 500℃. The porosity of its carbon layer structure in the thickness direction is 40% to 70%, effectively extending the heat penetration path.

[0069] The thickness of the energy-absorbing framework layer 3 ranges from 6 to 12 mm, preferably 8 mm, and its density ranges from 40 to 80 kg / m³. 3 The specific energy absorption rate at room temperature is not less than 30%, the compression deformation is controlled at 10% to 25% when the drop impact load is 20 to 40 J, and the latent heat is absorbed by the internally embedded energy storage filler in the temperature range of 80℃ to 120℃. The latent heat absorption range is 80 to 150 J / g, which can keep the internal temperature rise rate of the cover from 3℃ / min, thus providing time redundancy for maintaining a safe temperature range for the gas cylinder liner.

[0070] The inner supporting shell 2 has a thickness ranging from 8 to 12 mm, preferably 10 mm. Its wall thickness gradually increases from the transition port to the bottle neck valve seat 103, with an increase ratio ranging from 1.2 to 1.5 times. The geometric tolerance at room temperature is controlled within ±0.2 mm to ensure a high-precision fit with the outer surface of the bottle and to provide a stable assembly reference in the snap-fit ​​connection area. When the temperature exceeds 200℃, the supporting shell undergoes uneven deformation due to differences in wall thickness, and the residual locking force in the axial direction gradually weakens. The snap-fit ​​structure can be released after being held in the temperature range of 250℃ to 300℃ for no more than 5 minutes, thus facilitating manual disassembly and replacement of the cover after an accident.

[0071] A second aspect of the present invention provides a hydrogen storage cylinder 1. For example... Figure 1 As shown, in some embodiments of the present invention, the hydrogen storage cylinder 1 includes a straight section 101 in the middle, an end cap 102, a valve seat 103 at the cylinder mouth, and a hydrogen storage cylinder cover as described in any of the above embodiments.

[0072] Two end caps 102 are provided, and are respectively located at the ends of the middle straight section 101; the bottle mouth valve seat 103 is located at the port of the end cap 102 away from the middle straight section 101.

[0073] The hydrogen storage cylinder cover includes two covers, which are respectively mounted on the end caps 102, and expose a straight section 101 in the middle between the two covers.

[0074] The present invention provides a hydrogen storage cylinder 1 in which, under thermal and mechanical coupling conditions, two enclosures act as preliminary response units, each providing initial protection at its respective end. When either end is subjected to flame burning or impact from a foreign object, the multi-level structure of the end enclosure first forms a thermal barrier and energy-absorbing buffer. The circumferentially distributed load-bearing path diffuses, rectifies, and attenuates the impact energy and thermal stress within a local area, reducing the effective input to the cylinder. Meanwhile, the other end enclosure remains in standby mode during this stage, providing symmetrical redundancy against possible secondary heat flow or reverse impact. As the handling progresses, the locking force of the end enclosure under high temperature gradually decreases according to a preset mechanism. Once the safety conditions are met, it can be unlocked and detached under a small axial external force, exposing the valve seat area for maintenance or replacement of external components. The straight section 101 in the middle is effectively delayed due to previous heating and remains in a safe operating temperature range, forming a coordinated safety link of localized danger, localized handling, and overall control. Therefore, by adopting an overall layout with double-ended enclosures and exposed middle section, we can achieve the best overall balance between thermal safety, mechanical safety, assembly and maintenance, and system integration while ensuring strong protection for critical end areas.

[0075] The preferred embodiments described herein are not intended to limit the scope of the invention. Any modifications and improvements made by those skilled in the art to the technical solutions of the invention without departing from the spirit of the invention should fall within the protection scope defined by the claims of the invention.

Claims

1. A multi-layer composite fireproof quick-installation hydrogen storage cylinder cover, characterized in that, It includes at least one cover that extends from the valve seat at the mouth of the hydrogen storage cylinder to a straight section in the middle of the hydrogen storage cylinder and is fitted onto the end cap of the hydrogen storage cylinder. The cover has a first port and a second port. The first port surrounds the valve seat of the hydrogen storage cylinder, and the second port surrounds the transition between the middle straight section and the end cap. The first port has a snap-fit ​​structure that is fitted to the valve seat. Along the radial direction of the hydrogen storage cylinder, the cover includes multiple sequentially arranged hierarchical structures from the inside to the outside, and each of the multiple hierarchical structures has a heating zone that decreases layer by layer from the outside to the inside along the radial direction. Each of the aforementioned hierarchical structures is activated when it is in the corresponding heated zone to form a fireproof layer that blocks heat from the hydrogen storage cylinder; Each of the aforementioned hierarchical structures forms a fireproof layer that blocks heat transfer to the hydrogen storage cylinder in different directions.

2. The hydrogen storage cylinder cover according to claim 1, characterized in that, The hierarchical structure, from the inside to the outside along the radial direction, consists of an inner load-bearing shell, an energy-absorbing skeleton layer, a flame-retardant and heat-insulating layer, and an outer layer. From the middle of the end cap towards the straight middle section and the bottle neck valve seat, the wall thickness of the energy-absorbing skeleton layer gradually decreases, and a protrusion is formed along the radial direction outward.

3. The hydrogen storage cylinder cover according to claim 2, characterized in that, The outer surface layer includes a silicone rubber coating layer, which is sintered and ceramicized when in the corresponding heating zone, and forms a ceramic barrier along the surface of the central straight section.

4. The hydrogen storage cylinder cover according to claim 2, characterized in that, The flame-retardant and heat-insulating layer includes an intumescent flame-retardant layer, which expands and foams when in the corresponding heated zone, and forms a low thermal conductivity carbon layer along the radial direction.

5. The hydrogen storage cylinder cover according to claim 4, characterized in that, A cavity is formed between the inner supporting shell, the energy-absorbing skeleton layer, and the flame-retardant and heat-insulating layer, and the cavity is used to accommodate the expansion of the flame-retardant and heat-insulating layer.

6. The hydrogen storage cylinder cover according to claim 2, characterized in that, The energy-absorbing skeleton layer includes a flame-retardant modified foamed polypropylene layer. When the flame-retardant modified foamed polypropylene layer is in the corresponding set heating zone, the embedded energy storage filler absorbs heat from the interior of the flame-retardant modified foamed polypropylene layer.

7. The hydrogen storage cylinder cover according to claim 2, characterized in that, The inner supporting shell includes an engineering plastic layer, with the first port and the second port located at the ends of the engineering plastic layer, and the wall thickness of the engineering plastic layer gradually increases from the second port to the first port. When the engineering plastic layer is in the corresponding heating zone, the stress acting on the buckle structure is adjusted along the direction of increasing wall thickness.

8. The hydrogen storage cylinder cover according to claim 7, characterized in that, The snap-fit ​​structure includes: An inverted triangular locking block engages with an annular groove on the bottle neck valve seat. The connecting edge is used to connect the inverted triangular block and the engineering plastic layer.

9. The hydrogen storage cylinder cover according to claim 2, characterized in that, The protruding portion is formed with a flat surface and an arc-shaped surface, and the flame-retardant heat-insulating layer and the outer surface layer extend along the flat surface and / or the arc-shaped surface, respectively.

10. A hydrogen storage cylinder, characterized in that, It includes a straight middle section, end caps, a valve seat at the bottle mouth, and a hydrogen storage cylinder cover as described in any one of claims 1-9; Two end caps are provided, and each is located at the end of the straight middle section; the bottle mouth valve seat is located at the port of the end cap away from the straight middle section; The hydrogen storage cylinder cover includes two covers, which are respectively disposed on the end caps, and expose the middle straight section between the two covers.

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