Double-layer co-body type composite gas cylinder, preparation method thereof and vehicle-mounted gas supply system

Abstract

This invention belongs to the technical field of vehicle-mounted gas supply systems and gas cylinders, providing a double-layered composite gas cylinder and its preparation method, as well as a vehicle-mounted gas supply system. The composite gas cylinder includes an inner high-pressure resistant cavity, comprising a plastic liner and a first composite material layer; one end of the plastic liner has a high-pressure inlet / outlet, and the other end has a supporting member; an outer low-pressure resistant cavity includes an outer liner and a second composite material layer; the outer liner completely covers the supporting member and partially covers the high-pressure inlet / outlet, and correspondingly has low-pressure inlet / outlet openings; the inner high-pressure resistant cavity and the outer low-pressure resistant cavity are fixedly connected at both ends axially to form a co-located double-layered cavity structure; the inner cavity of the outer low-pressure resistant cavity constitutes a low-pressure chamber, and the inner cavity of the inner high-pressure resistant cavity constitutes a high-pressure chamber. The first composite material layer is configured to only bear the pressure difference between the high-pressure chamber pressure and the low-pressure chamber pressure. This invention simplifies vehicle mounting, reduces costs, and minimizes vehicle assembly space.

Description

Technical Field

[0001] This application relates to the technical field of vehicle-mounted gas supply systems and gas cylinders, and particularly to a double-layered composite gas cylinder and its preparation method, as well as a vehicle-mounted gas supply system. Background Technology

[0002] In practical applications of vehicle-mounted central air supply systems, a stepped inflation strategy is typically employed to effectively reduce the compressor's pressure ratio and improve energy efficiency. First, the compressor is controlled to inflate the low-pressure chamber (low-pressure cylinder) until a preset lower operating pressure, such as 8 Bar, is reached. Then, the gas in this low-pressure cylinder is used as the compressor's intake, undergoing secondary pressurization to reach a higher operating pressure, such as 15 Bar, before being injected into the high-pressure chamber (high-pressure cylinder). During vehicle operation, the system continuously monitors and replenishes the pressure in the low-pressure cylinder to maintain this stepped inflation cycle. Based on this supply logic, devices with different pressure requirements in the vehicle system can draw air from either the high-pressure or low-pressure cylinders, achieving separate air supply sources.

[0003] However, existing technologies have significant drawbacks in achieving this function: to meet the requirements of both high and low pressure, separate high-pressure and low-pressure gas cylinders must be configured. This split-type structural design not only increases the number of parts and manufacturing costs, but also makes the pipeline connections and fixing structure of the entire vehicle extremely complex, while severely encroaching on the limited interior space.

[0004] Furthermore, although existing technologies offer various gas cylinder design schemes and vehicle-mounted gas supply system design schemes, none of them can effectively solve the aforementioned problems. For example, patent CN222352068U discloses an integrated gas cylinder, comprising a high-pressure gas cylinder and several low-pressure gas cylinders arranged coaxially, with the low-pressure gas cylinders nested around the high-pressure gas cylinder to form an integrated gas cylinder structure for providing different pressure gas sources. This utility model also features a coaxially arranged high-pressure gas cylinder and several low-pressure gas cylinders, with the low-pressure gas cylinders sequentially nested around the high-pressure gas cylinder to form an integrated gas cylinder structure for providing different pressure gas sources, while also occupying a small area. Although this solution utilizes an outer low-pressure chamber to enclose an inner low-pressure chamber, it still consists of multiple gas cylinders, each chamber still independently bearing absolute pressure, resulting in complex manufacturing processes and the absence of a pressure differential load reduction design. This neither reduces the amount and weight of composite materials nor simplifies the vehicle-mounted gas supply control logic.

[0005] For example, patent CN217273513U discloses a vehicle-mounted gas supply system and a car. The vehicle-mounted gas supply system includes: a gas cylinder, which is a double-layered container with an inner liner and an outer shell. The inner liner and the outer shell are separated by a vacuum-insulated interlayer. The inner liner has a liquid phase space at the bottom for holding liquefied gas and a gas phase space at the top. The bottom of the inner liner is provided with a liquid supply port. The liquid supply port is connected to the outside through a liquid supply pipeline. The liquid supply pipeline is connected to a pumping device outside the gas cylinder. The pumping device is used to pump the liquefied gas toward the power system. Between the pumping device and the power system, there are sequentially arranged a flow valve, a first one-way valve, a water bath vaporizer, a buffer tank, a pressure regulating valve, a flow regulating valve, and a shut-off valve. A first-stage safety valve and a first pressure sensor are also provided between the water bath vaporizer and the buffer tank. Although this scheme adopts a double-layer differential pressure structure for a gas cylinder, it directly draws liquid medium from the vacuum-insulated inner liner through an external / internal cryogenic submersible pump, vaporizes it, and supplies it to the power system. It also relies on the vacuum insulation layer to reduce heat leakage and avoid the drawbacks of heat transfer to the cylinder by the self-pressurizing heat exchanger. The problems it solves are the cold preservation of cryogenic liquids such as liquid hydrogen, the control of temperature rise inside the cylinder, and the impact of self-pressurization on the gas cylinder, rather than the storage and staged supply of high-pressure gaseous air. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a double-layer integrated composite gas cylinder and its preparation method, as well as a vehicle-mounted gas supply system. The system is easy to fix in the vehicle, which can reduce costs and vehicle assembly space.

[0007] To achieve the above and related objectives, the present invention employs the following technical means:

[0008] The first aspect of this invention provides a double-walled, integrated composite gas cylinder, comprising:

[0009] The inner high-pressure resistant cavity includes a plastic inner liner and a first composite material layer covering the outer periphery of the plastic inner liner; one end of the plastic inner liner is provided with a high-pressure air inlet and outlet, and the other end is provided with a support member extending axially for positioning and supporting the outer low-pressure resistant cavity.

[0010] The outer low-pressure resistant cavity includes an outer liner and a second composite material layer covering the outer periphery of the outer liner; the outer liner is entirely covered by the supporting structure and partially covers the high-pressure air inlet and outlet, and a low-pressure air inlet and outlet is provided at the corresponding position of the high-pressure air inlet and outlet.

[0011] The inner high-pressure resistant cavity and the outer low-pressure resistant cavity are fixedly connected at both ends in the axial direction to form a common double-layer cavity structure; the inner cavity of the outer low-pressure resistant cavity constitutes the low-pressure air chamber, and the inner cavity of the inner high-pressure resistant cavity constitutes the high-pressure air chamber. The low-pressure air chamber and the high-pressure air chamber are independent of each other and coaxially nested.

[0012] The first composite material layer is configured to withstand only the pressure difference between the high-pressure chamber pressure and the low-pressure chamber pressure.

[0013] Furthermore, the support member is a protruding structure extending axially along the plastic liner, and its cross-sectional shape is selected from one or more of the following: circular, elliptical, rectangular, or polygonal.

[0014] Furthermore, the outer liner covers the side wall area of ​​the high-pressure air inlet and outlet, and a low-pressure air inlet and outlet is opened at the position corresponding to the high-pressure air inlet and outlet, so that the low-pressure air inlet and outlet and the high-pressure air inlet and outlet are spatially adjacent but the airflow channels are independent of each other.

[0015] Furthermore, the first composite material layer and the second composite material layer are each independently selected from fiber-reinforced resin-based composite materials.

[0016] Furthermore, the thickness of the second composite material layer is less than the thickness of the first composite material layer.

[0017] A second aspect of this invention provides a method for preparing a double-layered composite gas cylinder, comprising the following steps:

[0018] S1. Prepare a plastic inner liner for the inner high-pressure resistant cavity, integrally form a high-pressure air inlet and outlet at one end of the plastic inner liner, and set a support member extending outward along the axial direction at the other end;

[0019] S2. Fiber-reinforced composite material is wound around the outer peripheral surface of the plastic liner to form a first composite material layer, and then heated and cured to obtain a pre-made inner high-pressure resistant cavity with the first composite material layer.

[0020] S3. Using the supporting component as the forming support, an outer liner of the outer low-pressure cavity is set on the outside of the inner high-pressure cavity preform, so that the outer liner completely covers the supporting component and partially covers the high-pressure air inlet and outlet, and a low-pressure air inlet and outlet is reserved at a position offset from the high-pressure air inlet and outlet, thereby forming an inner and outer double-layer cavity preform.

[0021] S4. Fiber-reinforced composite material is wound around the outer periphery of the outer liner to form a second composite material layer, and then heated and cured to form a pressure-bearing shell reinforced with composite material for the inner high-pressure cavity and the outer low-pressure cavity respectively.

[0022] S5. The inner high-pressure resistant cavity and the outer low-pressure resistant cavity are fixedly connected at both ends of the axial direction by thermoplastic welding or bonding, so that the two form a common double-layer cavity structure;

[0023] Among them, the internal pressure of the inner high-pressure resistant cavity and the internal pressure of the outer low-pressure resistant cavity are set to have a pressure difference when in operation. The thickness and winding parameters of the first composite material layer are designed according to the pressure difference.

[0024] Furthermore, in step S3, the outer liner is combined with the supporting component and the local area of ​​the high-pressure air inlet and outlet by hot-melt welding or bonding to form a nested structure that fully covers the supporting component and partially covers the high-pressure air inlet and outlet.

[0025] Furthermore, in steps S2 and S4, the first composite material layer and the second composite material layer are both wound using a wet or dry fiber winding process, and cured under heating conditions after winding; the winding thickness of the first composite material layer is greater than the winding thickness of the second composite material layer.

[0026] Furthermore, in step S5, the fixed connection at both ends of the axial direction is achieved by plastic hot melt welding, ultrasonic welding, or structural adhesive bonding, so that the corresponding ends of the inner high-pressure resistant cavity and the outer low-pressure resistant cavity are respectively connected into a sealed integrated structure.

[0027] A third aspect of the present invention provides a vehicle-mounted gas supply system, comprising the above-described double-layer integrated composite gas cylinder, or comprising a double-layer integrated composite gas cylinder prepared according to the above-described preparation method.

[0028] The beneficial technical effects of this invention are as follows:

[0029] This invention constructs a double-layered structure by coaxially nesting and fixing an inner high-pressure resistant chamber and an outer low-pressure resistant chamber. The outer low-pressure chamber provides back pressure support to the inner high-pressure resistant chamber, ensuring that the first composite material layer on the high-pressure side only bears the pressure difference between the high-pressure and low-pressure chambers, rather than absolute high pressure. This significantly reduces the thickness of the first composite material layer, resulting in overall weight reduction and lower material costs for the gas cylinder. Through the overall covering of the support components and the partial covering of the high-pressure inlet and outlet, the invention achieves physical isolation, coaxial nesting, and integrated molding of the two chambers. This can replace the traditional separate arrangement of high- and low-pressure gas cylinders in vehicles, reducing the overall vehicle installation space and the complexity of the fixing brackets.

[0030] The preparation method of this invention can achieve co-solidification, and the process is consistent and the positioning accuracy is high, which is conducive to ensuring the coaxiality of the two cavities and the reliability of the seal. It is suitable for the integrated gas supply needs of gas-using equipment with different pressure levels in vehicle central gas source systems.

[0031] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0032] The accompanying drawings, incorporated in and forming part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without inventive effort. In the drawings:

[0033] Figure 1 This is a schematic diagram of the overall structure of the double-layer integrated composite gas cylinder of this application;

[0034] Figure 2 This is a schematic diagram of the plastic inner liner structure of the high-pressure resistant cavity inside this application;

[0035] Figure 3 This is a schematic diagram of the high-pressure resistant cavity structure inside this application;

[0036] Figure 4 This is a schematic diagram of the outer liner structure of the low-pressure resistant cavity in this application;

[0037] Figure 5 This is a schematic diagram of the high-pressure inlet / outlet and the low-pressure inlet / outlet structures of this application.

[0038] Figure Labels

[0039] 1: Inner high-pressure resistant cavity; 11: Plastic inner liner; 12: First composite material layer; 13: High-pressure air chamber; 14: Supporting component; 15: High-pressure air inlet and outlet; 2: Outer low-pressure resistant cavity; 21: Outer liner; 22: Second composite material layer; 23: Low-pressure air inlet and outlet; 24: Low-pressure air chamber. Detailed Implementation

[0040] Unless otherwise defined, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should be understood that certain features of the invention (described in the context of separate embodiments for clarity) may also be provided in a single embodiment. Conversely, multiple features of the invention (described in the context of a single embodiment for brevity) may also be provided separately or in any suitable combination or, where appropriate, in any other described embodiment of the invention. Certain features described in the context of various embodiments will not be considered essential features of those embodiments unless the embodiment is inoperable without those elements. The invention is further illustrated below by specific examples; however, it should be noted that the specific process conditions and results described in the embodiments of the invention are merely illustrative and should not be construed as limiting the scope of protection of the invention. All equivalent changes or modifications made in accordance with the spirit and essence of the invention should be covered within the scope of protection of the invention.

[0041] like Figures 1 to 5 As shown, this application provides a double-walled integrated composite gas cylinder, comprising:

[0042] The inner high-pressure resistant cavity 1 includes a plastic inner liner 11 and a first composite material layer 12 covering the outer periphery of the plastic inner liner 11; one end of the plastic inner liner 11 is provided with a high-pressure air inlet / outlet 15, and the other end is provided with a support member 14 extending axially for positioning and supporting the outer low-pressure resistant cavity 2.

[0043] The outer low-pressure resistant cavity 2 includes an outer liner 21 and a second composite material layer 22 covering the outer periphery of the outer liner 21; the outer liner 21 is entirely covered by the support member 14 and partially covers the high-pressure air inlet and outlet 15, and a low-pressure air inlet and outlet 23 is provided at the position corresponding to the high-pressure air inlet and outlet 15.

[0044] The inner high-pressure resistant cavity 1 and the outer low-pressure resistant cavity 2 are fixedly connected at both ends in the axial direction to form a common double-layer cavity structure; the inner cavity of the outer low-pressure resistant cavity 2 constitutes the low-pressure air chamber 24, and the inner cavity of the inner high-pressure resistant cavity 1 constitutes the high-pressure air chamber 13. The low-pressure air chamber 24 and the high-pressure air chamber 13 are independent of each other and coaxially nested; wherein, the first composite material layer 12 is constructed to only bear the pressure difference between the internal pressure of the high-pressure air chamber 13 and the internal pressure of the low-pressure air chamber 24.

[0045] Furthermore, such as Figures 1 to 4 As shown, the support member 14 of this application is a protruding structure extending axially along the plastic inner liner 11, and its cross-sectional shape is selected from one or more combinations of circles, ellipses, rectangles, or polygons. The support member 14 is integrally formed with the plastic inner liner 11, eliminating the need for additional fasteners, thereby reducing mass and leakage points, and utilizing vehicle lightweighting and simplified assembly. The support member 14 defines the relative position between the outer low-pressure resistant cavity 2 and the inner high-pressure resistant cavity 1 in the axial direction, ensuring a uniform and controllable pressure differential cavity gap between the two cavities. Furthermore, the support member 14, embedded in the outer outer liner 21 and the second composite material layer 22, can transfer part of the radial / axial shear force between the two cavities, thereby enhancing the overall rigidity of the double-layer co-structure. In addition, during the molding process of the outer low-pressure resistant cavity 2, the support member 14 can also serve as a positioning reference and anti-rotation function. This application uses the support member 14 to reliably cover the inner high-pressure resistant cavity 1 with the outer low-pressure resistant cavity 2, so that the high-pressure cavity only bears the pressure difference between the internal and external pressures rather than absolute high pressure. Combined with the reduction of the thickness of the first composite material layer 12, the purpose of cost reduction and weight reduction can be achieved.

[0046] Furthermore, such as Figure 5As shown, the outer liner 21 of this application covers the side wall area of ​​the high-pressure air inlet / outlet 15, and a low-pressure air inlet / outlet 23 is opened at a position corresponding to the high-pressure air inlet / outlet 15, so that the low-pressure air inlet / outlet 23 and the high-pressure air inlet / outlet 15 are spatially adjacent but their airflow channels are independent. Furthermore, the spatially adjacent arrangement of the low-pressure air inlet / outlet 23 and the high-pressure air inlet / outlet 15 facilitates centralized connection of the vehicle's pipelines, and high-pressure gas only enters and exits the inner high-pressure resistant cavity 1 through the high-pressure air inlet / outlet 15, and low-pressure gas only enters and exits the outer low-pressure resistant cavity 2 through the low-pressure air inlet / outlet 23, which can effectively prevent cross-contamination and ensure the function of separate air supply. When the outer low-pressure resistant cavity 2 is inflated, the outer wall of the inner high-pressure resistant cavity 1 directly bears the pressure difference between the internal high pressure and the external low pressure, rather than absolute high pressure. Therefore, the thickness of the first composite material layer 12 in this application can be reduced. At the same time, the outer liner 21 only needs to withstand a lower internal pressure, and the thickness of the second composite material layer 22 can also be reduced, thereby significantly reducing the total weight of the gas cylinder and the material cost while ensuring safety.

[0047] Furthermore, when the outer low-pressure resistant cavity 2 is filled with compressed air at a pressure of 8 Bar, the inner high-pressure resistant cavity 1 can safely accommodate compressed air at a pressure of 15 Bar with a significantly reduced thickness of the first composite material layer 12. At this time, the actual load borne by the outer wall of the inner high-pressure resistant cavity 1 is the internal and external pressure difference, approximately 7 Bar, rather than the absolute pressure of 15 Bar. Based on this pressure difference design, both the first composite material layer 12 and the second composite material layer 22 can be made thinner, thereby achieving a significant reduction in the overall weight and manufacturing cost of the gas cylinder while ensuring pressure resistance safety.

[0048] Furthermore, the first composite material layer 12 and the second composite material layer 22 of this application are each independently selected from fiber-reinforced resin-based composite materials, such as carbon fiber reinforced resin, glass fiber reinforced resin, or hybrid systems thereof, wherein the thickness of the second composite material layer 22 is less than the thickness of the first composite material layer 12. Since the inner high-pressure resistant cavity 1 needs to withstand the pressure difference between its internal gas pressure and the outer low-pressure cavity pressure, the first composite material layer 12 is configured as the main pressure-bearing reinforcement layer; while the outer low-pressure resistant cavity 2 only withstands a lower internal and external pressure difference, the second composite material layer 22 only needs to meet the low-pressure bearing requirements. Therefore, through this differentiated thickness design, this application can reduce the total amount of composite materials used while ensuring the pressure-bearing safety of both high- and low-pressure cavities, achieving overall lightweighting and cost reduction of the gas cylinder.

[0049] Furthermore, when the dual-layer integrated composite gas cylinder of this application is used in a vehicle-mounted central gas supply system, its working principle is as follows:

[0050] First, an external air compressor fills the low-pressure chamber 24 of the outer low-pressure resistant chamber 2 with air until a preset low-pressure value, such as 8 Bar, is reached. Then, the gas in this low-pressure chamber 24 is used as the air compressor intake, pressurizing it to a set high-pressure value, such as 15 Bar, and then injected into the high-pressure chamber 13 of the inner high-pressure resistant chamber 1 through the high-pressure inlet / outlet 15. During operation, the system continuously replenishes pressure to maintain the pressure in the low-pressure chamber 24, causing the aforementioned pressurization cycle to repeat.

[0051] Because the high-pressure chamber 13 and the low-pressure chamber 24 are coaxially nested and isolated from each other, and the high-pressure cavity is subjected to the back pressure of the low-pressure chamber 24, the first composite material layer 12 only needs to withstand the pressure difference between the internal pressure of the high-pressure chamber 13 and the internal pressure of the low-pressure chamber 24, and does not need to directly withstand the entire absolute high pressure as in traditional high-pressure gas cylinders. Therefore, the first composite material layer 12 of the inner high-pressure resistant cavity 1 of this application can be significantly thinned, achieving lightweighting and cost reduction.

[0052] The equipment with different air pressure requirements on the vehicle can draw air from the high-pressure inlet / outlet 15 and the low-pressure inlet / outlet 23 respectively, so as to realize the separate supply of high and low pressure gas. Through the support component 14 and the fixed connection at both ends of the axis, the high and low pressure cavities are integrated into a single physical entity, thereby solving the problems of large space occupation and complicated assembly of traditional dual-bottle separation.

[0053] This application also provides a method for preparing the above-mentioned double-walled composite gas cylinder, including the following steps:

[0054] S1. Prepare a plastic inner liner for the inner high-pressure resistant cavity, integrally form a high-pressure air inlet and outlet at one end of the plastic inner liner, and set a support member extending outward along the axial direction at the other end;

[0055] S2. Fiber-reinforced composite material is wound around the outer peripheral surface of the plastic liner to form a first composite material layer, and then heated and cured to obtain a pre-made inner high-pressure resistant cavity with the first composite material layer.

[0056] S3. Using the supporting component as the forming support, an outer liner of the outer low-pressure cavity is set on the outside of the inner high-pressure cavity preform, so that the outer liner completely covers the supporting component and partially covers the high-pressure air inlet and outlet, and a low-pressure air inlet and outlet is reserved at a position offset from the high-pressure air inlet and outlet, thereby forming an inner and outer double-layer cavity preform.

[0057] S4. Fiber-reinforced composite material is wound around the outer periphery of the outer liner to form a second composite material layer, and then heated and cured to form a pressure-bearing shell reinforced with composite material for the inner high-pressure cavity and the outer low-pressure cavity respectively.

[0058] S5. The inner high-pressure resistant cavity and the outer low-pressure resistant cavity are fixedly connected at both ends of the axial direction by thermoplastic welding or bonding, so that the two form a common double-layer cavity structure;

[0059] Among them, the internal pressure of the inner high-pressure resistant cavity and the internal pressure of the outer low-pressure resistant cavity are set to have a pressure difference when in operation. The thickness and winding parameters of the first composite material layer are designed according to the pressure difference.

[0060] Furthermore, in step S2, the thickness, winding angle, and layup sequence of the first composite material layer are designed and calculated based on the set pressure difference and circumferential stress formula between the internal pressure and the external low-pressure cavity pressure during operation of the inner high-pressure cavity, so that the first composite material layer is designed to bear pressure based only on the pressure difference rather than absolute high pressure.

[0061] Furthermore, in step S3, the outer liner of this application is combined with the supporting component and the local area of ​​the high-pressure air inlet and outlet by hot-melt welding or bonding to form a nested structure that fully covers the supporting component and partially covers the high-pressure air inlet and outlet.

[0062] Furthermore, in steps S2 and S4, the first composite material layer and the second composite material layer are both wound using a wet or dry fiber winding process, and cured under heating conditions after winding; the winding thickness of the first composite material layer is greater than the winding thickness of the second composite material layer.

[0063] Furthermore, in step S5, the fixed connection at both ends of the axial direction of this application is achieved by plastic hot melt welding, ultrasonic welding, or structural adhesive bonding, so that the corresponding ends of the inner high-pressure resistant cavity and the outer low-pressure resistant cavity are respectively connected into a sealed integrated structure.

[0064] Furthermore, both the inner and outer plastic liner of this application are made of thermoplastic material.

[0065] This application also provides a vehicle-mounted gas supply system, including the above-mentioned double-layer integrated composite gas cylinder, or including a double-layer integrated composite gas cylinder prepared according to the above-mentioned preparation method.

[0066] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A double-walled, integrated composite gas cylinder, characterized in that, include: The inner high-pressure resistant cavity (1) includes a plastic inner liner (11) and a first composite material layer (12) covering the outer periphery of the plastic inner liner (11); one end of the plastic inner liner (11) is provided with a high-pressure air inlet and outlet (15), and the other end is provided with a support member (14) extending axially for positioning and supporting the outer low-pressure resistant cavity (2). The outer low-pressure resistant cavity (2) includes an outer liner (21) and a second composite material layer (22) covering the outer periphery of the outer liner (21); the outer liner (21) covers the support member (14) in its entirety and partially covers the high-pressure air inlet and outlet (15), and a low-pressure air inlet and outlet (23) is provided at the position corresponding to the high-pressure air inlet and outlet (15). The inner high-pressure resistant cavity (1) and the outer low-pressure resistant cavity (2) are fixedly connected at both ends in the axial direction to form a common double-layer cavity structure; the inner cavity of the outer low-pressure resistant cavity (2) constitutes a low-pressure air chamber (24), and the inner cavity of the inner high-pressure resistant cavity (1) constitutes a high-pressure air chamber (13). The low-pressure air chamber (24) and the high-pressure air chamber (13) are independent of each other and coaxially nested. The first composite material layer (12) is configured to withstand only the pressure difference between the pressure inside the high-pressure chamber (13) and the pressure inside the low-pressure chamber (24).

2. The double-walled integrated composite gas cylinder according to claim 1, characterized in that, The support member (14) is a protruding structure extending axially along the plastic inner liner (11), and its cross-sectional shape is selected from one or more combinations of circles, ellipses, rectangles or polygons.

3. The double-walled integrated composite gas cylinder according to claim 1, characterized in that, The outer liner (21) covers the side wall area of ​​the high pressure air inlet / outlet (15) and opens the low pressure air inlet / outlet (23) at the position corresponding to the high pressure air inlet / outlet (15) so that the low pressure air inlet / outlet (23) and the high pressure air inlet / outlet (15) are spatially adjacent but their airflow channels are independent of each other.

4. The double-walled integrated composite gas cylinder according to claim 1, characterized in that, The first composite material layer (12) and the second composite material layer (22) are each independently selected from fiber-reinforced resin-based composite materials.

5. The double-layered composite gas cylinder according to claim 1, characterized in that, The thickness of the second composite material layer (22) is less than the thickness of the first composite material layer (12).

6. A method for preparing a double-layered, integrated composite gas cylinder, characterized in that, Includes the following steps: S1. Prepare a plastic inner liner for the inner high-pressure resistant cavity, integrally form a high-pressure air inlet and outlet at one end of the plastic inner liner, and provide a support member extending outward along the axial direction at the other end; S2. Fiber-reinforced composite material is wound around the outer peripheral surface of the plastic liner to form a first composite material layer, and then heated and cured to obtain a pre-made inner high-pressure resistant cavity with the first composite material layer. S3. Using the support member as the forming support, an outer liner of the outer low-pressure cavity is provided on the outside of the inner high-pressure cavity preform, so that the outer liner completely covers the support member and partially covers the high-pressure air inlet and outlet, and a low-pressure air inlet and outlet is reserved at a position offset from the high-pressure air inlet and outlet, thereby forming an inner and outer double-layer cavity preform. S4. Fiber-reinforced composite material is wound around the outer periphery of the outer liner to form a second composite material layer, and then heated and cured to form a pressure-bearing shell reinforced with composite material for the inner high-pressure resistant cavity and the outer low-pressure resistant cavity, respectively. S5. The inner high-pressure resistant cavity and the outer low-pressure resistant cavity are fixedly connected at both ends in the axial direction by thermoplastic welding or bonding, so that the two form a common double-layer cavity structure; In this process, there is a set pressure difference between the internal air pressure of the inner high-pressure resistant cavity and the internal air pressure of the outer low-pressure resistant cavity during operation. The thickness and winding parameters of the first composite material layer are designed according to the pressure difference.

7. The preparation method according to claim 6, characterized in that, In step S3, the outer liner is combined with the supporting member and a local area of ​​the high-pressure air inlet and outlet by hot-melt welding or bonding to form a nested structure that completely covers the supporting member and partially covers the high-pressure air inlet and outlet.

8. The preparation method according to claim 6, characterized in that, In steps S2 and S4, the first composite material layer and the second composite material layer are wound using either wet or dry fiber winding processes, and then cured under heating conditions after winding. The winding thickness of the first composite material layer is greater than that of the second composite material layer.

9. The preparation method according to claim 6, characterized in that, In step S5, the fixed connection at both ends of the axial direction is achieved by plastic hot melt welding, ultrasonic welding, or structural adhesive bonding, so that the corresponding ends of the inner high-pressure resistant cavity and the outer low-pressure resistant cavity are respectively connected into a sealed integrated structure.

10. A vehicle-mounted air supply system, characterized in that, Includes the double-layered composite gas cylinder according to any one of claims 1 to 5, or includes the double-layered composite gas cylinder prepared by the preparation method according to any one of claims 6 to 9.

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