Lightweight carbon fiber fully wound gas cylinder and its manufacturing method

Abstract

This invention relates to the field of gas cylinder structure and processing technology, and discloses a lightweight carbon fiber fully wound gas cylinder and its manufacturing method. The cylinder includes an inner liner, a carbon fiber composite layer disposed on the outer wall of the inner liner, and a glass fiber protective layer disposed on the outer surface of the carbon fiber composite layer. The inner liner is manufactured using a steel plate deep-drawing process, and the inner liner is formed with a single-sided tapered end. The carbon fiber composite layer includes a helical wound layer with a first preset angle and a circumferential wound layer with a second preset angle. The gas cylinder provided by this invention has stable performance and is lightweight, easy to manufacture, and can effectively reduce manufacturing and transportation costs, achieving lightweight and low-cost gas cylinder manufacturing.

Description

Technical Field

[0001] This invention relates to the field of gas cylinder structure and processing technology, specifically to a lightweight carbon fiber fully wound gas cylinder and its manufacturing method. Background Technology

[0002] Freight transport is one of the main modes of modern transportation and one of the two basic modes of land-based freight transport. It occupies an important position in the entire transportation sector and plays an increasingly vital role. Freight transport is less affected by climate and natural conditions, and its large transport capacity and per-vehicle loading capacity give it an advantage in terms of regularity.

[0003] As trucks are widely used land-based freight vehicles, their increasing numbers, coupled with limited fuel supply, have led to rising freight costs. To reduce these costs, trucks with lower transportation costs have become a major market demand. Natural gas (CNG) trucks perfectly meet this demand, especially for long-distance freight transport in regions like Xinjiang where natural gas is abundant (CNG costs less than 2 yuan per cubic meter). CNG trucks can save over 200,000 yuan annually compared to traditional diesel trucks, and their emissions are more environmentally friendly, offering greater environmental benefits.

[0004] However, natural gas trucks, as heavy-duty vehicles fueled by natural gas, require a large amount of natural gas to ensure their operational range. The continuous supply of natural gas necessitates carrying several large-capacity gas cylinders (compressed natural gas storage tanks) on the truck body. These cylinders add significant weight to the truck, impacting its load-bearing capacity. The considerable weight of the cylinders themselves also limits the actual amount of natural gas that can be carried, hindering improvements in range. To further optimize the load-bearing capacity, range, and economy of natural gas trucks, lightweighting and reducing the cost of gas cylinders are effective methods. However, how to reduce the weight and cost of the cylinders remains a pressing issue that needs to be addressed.

[0005] In addition, in the transportation of gas cylinders themselves, since the weight of goods that a single truck can carry is limited, the weight of the gas cylinders themselves often accounts for a large part of the weight of a single shipment in the current transportation of natural gas cylinders, which also leads to the high self-transportation cost of existing gas cylinders. Summary of the Invention

[0006] The present invention aims to provide a lightweight carbon fiber fully wound gas cylinder and its manufacturing method. The gas cylinder has stable performance and is lightweight, which is easy to manufacture and can effectively reduce manufacturing and transportation costs, thereby achieving lightweight and low-cost gas cylinders.

[0007] To achieve the above objectives, the basic solution provided by this invention is as follows:

[0008] Option 1

[0009] A lightweight carbon fiber fully wound gas cylinder includes an inner liner and a carbon fiber composite layer disposed on the outer wall of the inner liner; the inner liner is made by deep drawing of steel plate and is formed by single-sided closing; the carbon fiber composite layer includes a spiral wound layer with a winding angle of a first preset angle and a circumferential wound layer with a winding angle of a second preset angle.

[0010] Furthermore, the first preset angle is 8°–15°.

[0011] Furthermore, the second preset angle is 85°–90°.

[0012] Furthermore, the inner liner includes a bottle mouth, an upper sealing head, a cylindrical body, and a lower sealing head arranged sequentially; the spiral winding layer is wound around the inner liner; and the circumferential winding layer is wound around the cylindrical body.

[0013] Furthermore, it also includes a glass fiber protective layer disposed on the outer surface of the carbon fiber composite layer; the glass fiber protective layer is circumferentially wound around the cylinder body.

[0014] Furthermore, the wall thickness of the cylindrical body is 3.7mm-4.3mm.

[0015] Furthermore, a tail plug is provided on the bottom surface of the lower sealing head; the tail plug includes an integrally formed upper connecting part and a lower connecting part; a threaded hole is provided at the center of the upper connecting part; the bottom surface of the lower connecting part is a circular arc surface.

[0016] Option 2

[0017] A method for manufacturing a lightweight carbon fiber fully wound gas cylinder, used to manufacture a lightweight carbon fiber fully wound gas cylinder as described in Scheme 1; comprising the following steps:

[0018] Step 1: Select steel plate as the blank; use deep drawing process to draw the blank into a cup shape;

[0019] Step 2: Hot spin pressing is performed on the cup-shaped body to close the mouth, resulting in an inner liner with a single-ended bottle opening;

[0020] Step 3: Wrap a carbon fiber composite layer around the inner liner; wrap a glass fiber protective layer around the carbon fiber composite layer.

[0021] Furthermore, step 2 also includes attaching a tail plug to the bottom surface of the lower sealing head of the inner liner; the bottom surface of the lower connecting part of the tail plug is in contact with the bottom surface of the lower sealing head.

[0022] The working principle and advantages of this invention are as follows:

[0023] Firstly, the inner liner of this design is a steel liner made by deep drawing of steel plate and then hot spinning on one side to achieve uniform wall thickness distribution and stable cylinder quality. The single-sided sealing further reduces the inner liner wall thickness, particularly in the cylinder body, reducing it to 3.7mm-4.3mm, while ensuring wall thickness fluctuations are controlled within 0.6mm, resulting in higher production quality and manufacturing efficiency. In contrast, conventional double-ended inner liners, formed by sealing both ends of a steel pipe, suffer from larger wall thickness fluctuations (greater than or equal to 1mm) and cylinder body wall thicknesses often exceeding 10mm due to process limitations. The double-ended design also results in uneven wall thickness at the upper and lower sealing ends, making the overall inner liner heavier. This design effectively optimizes the inner liner quality through process and structural improvements. Under the same capacity conditions, this design offers a more uniform wall thickness distribution, more stable structural performance, and a lighter inner liner, significantly reducing transportation costs.

[0024] Secondly, this solution reduces and homogenizes the inner liner wall thickness while ensuring the inner liner's pressure-bearing capacity fully meets standards. This solution meticulously defines the winding method for the carbon fiber composite layer and the glass fiber protective layer. The carbon fiber composite layer is divided into a spiral winding layer and a circumferential winding layer, with specific limitations on their respective winding angles and areas. Under these winding conditions, this solution can achieve superior pressure-bearing performance for the inner liner with less winding material compared to conventional winding methods; it further reduces the weight of the gas cylinder while saving on carbon fiber composite layer material, significantly reducing production costs. Furthermore, the tail plug design, combined with a single-sided bottle opening, facilitates the connection of tooling and other support at both ends of the inner liner, enabling streamlined production and improving gas cylinder production efficiency. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the lightweight carbon fiber fully wound gas cylinder and its manufacturing method of the present invention.

[0026] Figure 2 This is an embodiment of the lightweight carbon fiber fully wound gas cylinder and its manufacturing method of the present invention. Figure 1 An enlarged schematic diagram of the structure at point I;

[0027] Figure 3 This is a schematic diagram of the bottle mouth structure in an embodiment of the lightweight carbon fiber fully wound gas cylinder and its manufacturing method of the present invention.

[0028] Figure 4 This is a schematic diagram of the lower sealing head structure of an embodiment of the lightweight carbon fiber fully wound gas cylinder and its manufacturing method of the present invention;

[0029] Figure 5 This is a schematic diagram of the spiral winding method of an embodiment of the lightweight carbon fiber fully wound gas cylinder and its manufacturing method of the present invention.

[0030] Figure 6 This is a schematic diagram of the circumferential winding layer in an embodiment of the lightweight carbon fiber fully wound gas cylinder and its manufacturing method of the present invention. Detailed Implementation

[0031] The following detailed explanation illustrates the specific implementation methods:

[0032] The markings in the accompanying drawings of the instruction manual include: inner liner 1, bottle mouth 2, bottle mouth 21, bottle mouth thread 22, upper sealing head 3, cylinder body 4, lower sealing head 5, tail plug 6, upper connecting part 61, lower connecting part 62, spiral winding layer 7, circumferential winding layer 8, and glass fiber protective layer 9.

[0033] The basic implementation examples are as follows: Figure 1 As shown: a lightweight carbon fiber fully wound gas cylinder includes an inner liner 1, a carbon fiber composite layer disposed on the outer wall of the inner liner 1, and a glass fiber protective layer 9 disposed on the outer surface of the carbon fiber composite layer.

[0034] The inner liner 1 is manufactured using a steel plate deep drawing process, and the inner liner 1 is formed with a single-sided tapered opening. The inner liner 1 includes a bottle mouth portion 2, an upper sealing head 3, a cylinder body portion 4, and a lower sealing head 5 arranged sequentially; wherein, the inner wall of the bottle mouth portion 21 is provided with a bottle mouth thread 22, which is used to connect positioning fixtures during the gas cylinder production process to facilitate gas cylinder processing, and is also used to connect the cylinder valve during gas cylinder use for easy assembly, as shown in the attached figure. Figure 3 As shown. The wall thickness of the upper sealing head 3 is greater than that of the body 4, and the wall thickness of the upper sealing head 3 decreases from near the bottle mouth 21 to near the body. Under this structural condition, the wall thickness of the upper sealing head 3 varies evenly, and the connection with the wall thickness of the body 4 is uniform, ensuring sufficient strength at the bottle mouth 21. The wall thickness of the body 4 is 3.7mm-4.3mm. The body wall is relatively thin, with wall thickness fluctuations controlled within 0.6mm, resulting in a uniform wall thickness distribution for the inner liner 1 and more stable structural quality. The overall weight of the inner liner 1 is also lighter, achieving better weight reduction and lower transportation costs.

[0035] As attached Figure 2As shown, the carbon fiber composite layer includes a spiral wound layer 7 with a first preset angle and a circumferential wound layer 8 with a second preset angle. The carbon fiber composite layer is made of high-performance carbon fiber impregnated with epoxy resin. The spiral wound layer 7 is wound onto the inner liner 1; the circumferential wound layer 8 is wound onto the cylinder body 4. The spiral wound layer 7 is in direct contact with the inner liner 1; the circumferential wound layer 8 is wound around the spiral wound layer 7. Specifically, the first preset angle is 8°–15°; the second preset angle is 85°–90°; the width of a single strand of the spiral wound layer 7 and the circumferential wound layer 8 is controlled within the range of 28–36 mm. A glass fiber protective layer 9 is circumferentially wound onto the cylinder body 4. The glass fiber protective layer 9 is made of glass fiber impregnated with epoxy resin; its winding method is the same as that of the circumferential wound layer 8 of the carbon fiber composite layer. Under this structural condition, the axial and circumferential strength of the inner liner 1 are enhanced, ensuring that the pressure-bearing performance of the gas cylinder meets the standard requirements; the glass fiber protective layer 9 can better protect the carbon fiber composite layer, ensuring that the carbon fiber composite layer can stably share the pressure.

[0036] As attached Figure 4 As shown, a tail plug 6 is provided on the bottom surface of the lower sealing head 5; the tail plug 6 includes an integrally formed upper connecting part 61 and a lower connecting part 62; a threaded hole is provided at the center of the upper connecting part 61; the bottom surface of the lower connecting part 62 is a circular arc surface. Specifically, the bottom surface of the lower connecting part 62 is in contact with the bottom surface of the lower sealing head 5 of the inner liner 1.

[0037] This embodiment also provides a method for manufacturing a lightweight carbon fiber fully wound gas cylinder, used to manufacture the lightweight carbon fiber fully wound gas cylinder as described above; including the following steps:

[0038] Step 1: Select steel plate as billet; use deep drawing process to draw the billet into a cup shape.

[0039] Specifically, in this embodiment, a large-tonnage press is used for three-stage cold deep drawing. Annealing and surface treatment processes are applied to the drawn billet between the first and second deep drawing processes, and between the second and third deep drawing processes. The deep drawing speed is controlled at 95–120 mm / min.

[0040] Furthermore, during annealing, the billet heating temperature is set to 805±10℃, followed by furnace cooling for 28–32 minutes. In the surface treatment process, the surface treatment is carried out in three steps: pickling, phosphating, and saponification. In the pickling step, a 26% sulfuric acid solution is used, with a corrosion inhibitor concentration of 0.45 g / L, a solution temperature of 50–60℃, and a pickling time of 20–18 minutes. In the phosphating step, a zinc-based phosphating solution is used, with a total acidity of 25–30 drops, a free acidity of 3–7 drops, a phosphating temperature of 65–80℃, and a phosphating time of 28–32 minutes. In the saponification step, a fatty acid saponification solution is used, with a concentration of 86 g / L, free alkali <0.3%, a temperature of 35–45℃, and a time of 10–12 minutes.

[0041] Step 2: The cup-shaped body is hot-spinned to form an inner liner 1 with a single-ended bottle mouth 21. The heating temperature during hot-spinning is set to 1157-1160℃.

[0042] Under the above process conditions, the lower sealing head 5 of the inner liner 1 has a thinner wall thickness and a more uniform thickness distribution. The upper sealing head 3 of the inner liner 1 has a thicker wall than the body 4, and the wall thickness of the upper sealing head 3 decreases from near the bottle mouth 21 to near the body. The body 4 has a uniform wall thickness distribution and a thickness controlled between 3.7mm and 4.3mm. Overall, the inner liner 1 has a uniform wall thickness, stable structural quality, and is relatively lightweight.

[0043] Specifically, the inner liner 1 is also subjected to heat treatment. In this embodiment, the heat treatment operations include metal quenching and tempering heat treatment, which can make the tensile strength of the steel inner liner 1 reach 950MPa, which can fully meet the pressure bearing standard requirements of the gas cylinder.

[0044] It also includes bonding a tail plug 6 to the bottom surface of the lower sealing head 5 of the inner liner 1; the bottom surface of the lower connecting part 62 of the tail plug 6 is attached to the bottom surface of the lower sealing head 5. Specifically, high-temperature resistant, high-strength adhesive is used to bond the lower connecting part 62 of the tail plug 6 to the bottom surface of the lower sealing head 5.

[0045] Step 3: Wrap a carbon fiber composite layer around the inner liner 1; wrap a glass fiber protective layer 9 around the carbon fiber composite layer.

[0046] Specifically, before winding, the inner liner 1 can be lifted by using a tool that engages with the bottle mouth 21 and the tail plug 6 bonded to the lower sealing head 5, and the screw thread of the tool engaging with the bottle mouth 21 and the tail plug 6, to facilitate the winding operation on the inner liner 1. (See attached...) Figure 5As shown, when the carbon fiber composite layer is wound, a spiral winding layer 7 is first set, and this layer starts from the R-angle where the bottle mouth 2 connects with the upper sealing head 3 and spirally winds to the tail plug 6, covering and wrapping the lower connecting part 62, upper sealing head 3, cylinder part 4 and lower sealing head 5 of the tail plug 6, which can greatly enhance the axial strength of the inner liner 1. Furthermore, the width of a single spiral winding layer 7 is controlled within the range of 28-36mm. This specific size setting ensures smooth transitions and tight wrapping of the spiral winding layer material at the R-corner, the bottle shoulder transition of the upper sealing head 3, and the bottom transition of the lower sealing head 5 during winding. Compared to directly wrapping with a wide material, although the winding steps are reduced and there are fewer seams between the winding materials, seemingly resulting in better pressure resistance and efficiency, the fit between the wide material and the curved inner liner 1 is actually not good. For the curved area, the edges of the winding material are prone to protrusion, requiring overlapping winding, resulting in more material consumption and poor pressure resistance. This solution, however, uses a specific width for winding, which can control the possible material overlap area to be smaller, resulting in higher material fit and maximizing the effectiveness of the carbon fiber composite layer material, ensuring full pressure resistance and reducing material consumption. In addition, with the tail plug 6 and bottle mouth 21, the two ends of the inner liner 1 are lifted for winding, ensuring sufficient winding efficiency of this solution.

[0047] Then, a circumferential winding layer 8 is set; and this layer starts from the connection between the upper sealing head 3 and the cylinder body 4 and winds circumferentially to the connection between the cylinder body 4 and the lower sealing head 5, covering and wrapping the entire cylinder body 4, which can greatly enhance the circumferential strength of the inner liner 1, as shown in the attached figure. Figure 6 As shown.

[0048] Furthermore, a glass fiber protective layer 9 is wound around the carbon fiber composite layer; and this layer is also wound circumferentially from the connection between the upper sealing head 3 and the cylinder body 4 to the connection between the cylinder body 4 and the lower sealing head 5, which can effectively protect the carbon fiber composite layer and ensure that the carbon fiber composite layer can withstand pressure stably.

[0049] In practical applications, the neck 21 of the inner liner 1 can be connected to the cylinder valve. Compressed natural gas is pressurized from the cylinder valve and forced into the inner liner 1 until the pressure reaches the working pressure of the gas cylinder, 20 MPa. During this process, the inner liner 1 expands under pressure and undergoes elastic deformation, transferring the pressure to the carbon fiber composite layer on the outer surface of the inner liner 1. The materials of the inner liner 1 and the carbon fiber composite layer together withstand the internal pressure of 20 MPa, thus serving to store high-pressure natural gas. At the same time, the glass fiber protective layer 9 continuously protects the carbon fiber composite layer, ensuring the overall pressure stability of the gas cylinder.

[0050] The gas cylinders provided in this solution, with a capacity of 260L, weigh as little as 126Kg per cylinder, a 10% reduction compared to ordinary cylinders of the same capacity. Consequently, when transporting these cylinder sets by trucks, the increase in overall vehicle weight is minimal, allowing a single vehicle to carry more cylinders and transport larger quantities of compressed natural gas, significantly reducing transportation costs. Furthermore, for CNG trucks (natural gas trucks), the cylinders provided by this solution impose less weight on the vehicle, enabling CNG trucks to easily carry more cylinders and achieve longer driving ranges. The lower production cost of the cylinders further reduces the configuration costs of CNG trucks, enhancing their economic efficiency. The application of this gas cylinder can effectively promote the development of CNG trucks and contribute to energy conservation and emission reduction.

[0051] This embodiment provides a lightweight carbon fiber fully wound gas cylinder and its manufacturing method. The inner liner 1 is a steel inner liner 1 made by deep drawing steel plate and then hot spinning it on one side. The single-sided sealing ensures uniform wall thickness distribution and stable cylinder quality. The inner liner 1 has a relatively small wall thickness, especially the body portion 4, which is reduced to 3.7mm-4.3mm, and the wall thickness fluctuation can be controlled within 0.6mm (compared to at least 1mm fluctuation in conventional gas cylinder production). This results in higher production quality and higher manufacturing efficiency (achieving an optimal manufacturing efficiency of 3 minutes per cylinder in this embodiment). Furthermore, while reducing and uniformizing the wall thickness of the inner liner 1, the pressure-bearing capacity of the inner liner 1 is also fully guaranteed to meet the standards.

[0052] In particular, by precisely defining the winding method of the carbon fiber composite layer and the glass fiber protective layer 9, less winding material can be used to help the inner liner 1 achieve better pressure-bearing performance compared to conventional winding. With a reduced inner liner 1 wall thickness, the weight of the gas cylinder can be further reduced while ensuring that the overall pressure-bearing performance of the gas cylinder absolutely meets the standards, saving on the carbon fiber composite layer material. Furthermore, this solution saves on winding material because specific process settings allow for highly uniform control of the inner liner 1 wall thickness. The wall strength distribution within each region of the inner liner 1 is uniform, and the strength fluctuation is smaller compared to conventional gas cylinders. For the carbon fiber composite layer, its winding uniformity is also correspondingly improved, helping to reduce the amount of carbon fiber composite layer used. Moreover, the carbon fiber composite layer material is high-performance carbon fiber impregnated with epoxy resin, whose material performance is superior to conventional carbon fiber materials, enabling the carbon fiber composite layer to efficiently exert its pressure-bearing effect. Furthermore, because the amount of carbon fiber composite layer and inner liner 1 material is reduced, even with the use of superior carbon fiber materials, the production cost of this solution remains low, and the cost of the gas cylinder is reduced by 20% compared to conventional gas cylinders of the same capacity.

[0053] The above descriptions are merely embodiments of the present invention. Commonly known structures and characteristics of the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are aware of all existing technologies in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A lightweight carbon fiber fully wound gas cylinder, characterized in that, The device includes an inner liner and a carbon fiber composite layer disposed on the outer wall of the inner liner. The inner liner is manufactured using a steel plate deep drawing process and is formed with a single-sided tapered opening. The carbon fiber composite layer includes a spiral winding layer with a first preset angle and a circumferential winding layer with a second preset angle. The first preset angle is 8°–15°, and the second preset angle is 85°–90°. The inner liner includes a bottle mouth, an upper sealing head, a cylindrical body, and a lower sealing head arranged sequentially. The spiral winding layer is wound around the inner liner, and the circumferential winding layer is wound around the cylindrical body. It also includes a glass fiber protective layer disposed on the outer surface of the carbon fiber composite layer; the glass fiber protective layer is circumferentially wound around the cylindrical body; the wall thickness of the cylindrical body is 3.7mm-4.3mm; The deep drawing process includes three cold deep drawing processes, and annealing and surface treatment processes are used to treat the deep-drawn blank between the first and second deep drawing processes and between the second and third deep drawing processes; and the deep drawing speed is controlled at 95-120 mm / min. Furthermore, during annealing, the billet heating temperature is set to 805±10℃, followed by furnace cooling for 28–32 minutes. In the surface treatment process, the surface treatment is carried out in three steps: pickling, phosphating, and saponification. In the pickling step, a 26% sulfuric acid solution is used, with a corrosion inhibitor concentration of 0.45 g / L, a solution temperature of 50–60℃, and a pickling time of 20–18 minutes. In the phosphating step, a zinc-based phosphating solution is used, with a total acidity of 25–30 drops, a free acidity of 3–7 drops, a phosphating temperature of 65–80℃, and a phosphating time of 28–32 minutes. In the saponification step, a fatty acid saponification solution is used, with a concentration of 86 g / L, free alkali <0.3%, a temperature of 35–45℃, and a time of 10–12 minutes.

2. The lightweight carbon fiber fully wound gas cylinder according to claim 1, characterized in that, A tail plug is provided on the bottom surface of the lower sealing head; the tail plug includes an integrally formed upper connecting part and a lower connecting part; a threaded hole is provided at the center of the upper connecting part; the bottom surface of the lower connecting part is a circular arc surface.

3. A method for manufacturing a lightweight carbon fiber fully wound gas cylinder, characterized in that, For manufacturing a lightweight carbon fiber fully wound gas cylinder as described in any one of claims 1-2; comprising the following steps: Step 1: Select steel plate as the blank; use deep drawing process to draw the blank into a cup shape; Step 2: Hot spin pressing is performed on the cup-shaped body to close the mouth, resulting in an inner liner with a single-ended bottle opening; Step 3: Wrap a carbon fiber composite layer around the inner liner; wrap a glass fiber protective layer around the carbon fiber composite layer.

4. The method for manufacturing a lightweight carbon fiber fully wound gas cylinder according to claim 3, characterized in that, Step 2 also includes attaching a tail plug to the bottom surface of the lower sealing head of the inner liner; the bottom surface of the lower connecting part of the tail plug is in contact with the bottom surface of the lower sealing head.

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