A plastic gas storage tank and a secondary injection filling pressurization processing method thereof

Abstract

A plastic gas tank and a secondary injection filling pressurization processing method thereof, the method comprising the following steps: through three sets of injection molds, first put the inlet and outlet valve into the first set of injection mold, the inlet and outlet valve is used as an insert to be injection molded to obtain an upper main body with the inlet and outlet valve, the middle main body is injection molded by the second set of injection mold, and the lower main body is injection molded by the third set of injection mold; the upper main body, one or more middle main bodies and the lower main body are stacked in sequence to form a gas storage cavity inside, and the gas tank is obtained by welding the connection between the upper cover, the middle cylinder and the lower cover; 7MPa-12MPa nitrogen gas is injected into the gas storage cavity through the inlet and outlet valve by a gas pump; the inner gas tank after pressurization is used as an insert to be put into the fourth set of injection mold, a layer of tank body is injection molded on the outer wall of the inner gas tank to obtain the plastic gas tank; and the nitrogen gas in the plastic gas tank is extracted through the inlet and outlet valve by an air extraction pump.

Description

Technical Field

[0001] This invention relates to a plastic gas storage tank and its secondary injection molding, filling, and pressurization process, belonging to the field of gas storage tank processing technology. Background Technology

[0002] Gas storage tanks are devices specifically designed for storing gases. Based on the materials used, they can be mainly divided into metal gas storage tanks (usually stainless steel), carbon fiber gas storage tanks, and plastic gas storage tanks. Metal gas storage tanks are widely used due to their high structural strength, low cost, and ease of manufacturing. However, when storing hydrogen, hydrogen can permeate into the metal and react chemically, causing phenomena such as "hydrogen damage," "hydrogen erosion," and "hydrogen corrosion." Therefore, metal gas storage tanks are unsuitable for storing hydrogen. Carbon fiber gas storage tanks are expensive and not widely used. Plastic gas storage tanks have low production costs and hydrogen does not cause "hydrogen damage," "hydrogen erosion," or "hydrogen corrosion." However, due to the lower structural strength of plastic, their pressure resistance is poor, resulting in a typically small volume and limited hydrogen storage capacity. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a plastic gas storage tank and its secondary injection molding filling and pressurization processing method, which features high structural strength, strong pressure resistance, large gas storage capacity, low production cost, fast pressurization speed, and convenient manufacturing.

[0004] The technical solution of the present invention for a plastic gas storage tank is as follows: it includes an upper body, a middle body, a lower body, and a tank body made of PA6 or PA12 material. The upper body is composed of four or more upper covers, one of which is provided with an inlet / outlet valve. An upper baffle is provided between each upper cover. The middle body is located below the upper body. The middle body is composed of four or more middle cylinders, the upper opening of which corresponds to the lower opening of the upper cover. The lower body is located below the middle body. The lower body is composed of four or more lower covers, the lower baffle is provided between each lower cover, and the upper opening of the lower cover corresponds to the lower opening of the middle cylinder. The upper body, middle body, and lower body are stacked sequentially. Each corresponding upper cover, middle cylinder, and lower cover forms a gas storage chamber. A through hole is provided between each gas storage chamber. The outer walls of the upper, middle, and lower bodies are all covered by a tank body. The upper part of the inlet / outlet valve passes through the tank body.

[0005] Furthermore, the main body is in one or more groups, with each group of main bodies stacked vertically, and the middle cylinders of each group of main bodies stacked vertically.

[0006] Furthermore, a positioning and insertion structure is provided between the upper cover and the middle cylinder, a positioning and insertion structure is provided between the stacked middle cylinders, and a positioning and insertion structure is provided between the middle cylinder and the lower cover.

[0007] Furthermore, the positioning and insertion structure includes positioning ribs at the lower openings of the upper cover and the middle cylinder, positioning rings at the upper openings of the middle cylinder and the lower cover, positioning grooves in the positioning rings, and positioning ribs and positioning grooves engaging in positioning and insertion.

[0008] Furthermore, the inner wall of the middle cylinder is provided with supporting ribs.

[0009] This invention discloses a secondary injection molding filling and pressurization process for a plastic gas storage tank, the method comprising the following steps: ① First injection molding: Using PA6 or PA12 material, through three injection molds, the air inlet and outlet valves are first placed in the first injection mold and injection molded as inserts to obtain the upper body with air inlet and outlet valves. The upper body has four or more upper covers. The middle body is injection molded by the second injection mold. The middle body has four or more middle cylinders. The lower body is injection molded by the third injection mold. The lower body has four or more lower covers. Through holes are opened on the side wall of the upper cover, middle cylinder or lower cover. ② Welding connection: The upper body, one or more middle bodies and the lower body are stacked one on top of the other. After the upper cover, middle cylinder and lower cover are stacked, an internal gas storage chamber is formed. The upper cover, middle cylinder and lower cover are welded together by welding gun to obtain the inner gas tank. ③ Gas pressurization: Nitrogen gas at 7MPa-12MPa is injected into the gas storage chamber through the inlet and outlet valves using an air pump; ④ Secondary injection molding: The pressurized inner gas tank is placed as an insert into the fourth injection mold, and a layer of tank body is injected into the outer wall of the inner gas tank to obtain a plastic gas storage tank. ⑤ Exhaust: The nitrogen gas in the plastic gas storage tank is extracted through the inlet and outlet valves using an air pump.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: First, the upper body, middle body, and lower body are injection molded separately, and then the upper, middle, and lower bodies are stacked and connected by welding. The upper, middle, and lower bodies are manufactured separately, and supporting ribs and reinforcing ribs can be arranged in the upper cover, middle cylinder, and lower cover. On the one hand, this is conducive to core pulling and demolding; on the other hand, under the premise of ensuring structural strength, different numbers of middle bodies can be stacked to manufacture plastic gas tanks of different heights and gas storage capacities, meeting the needs of different people and having better versatility. Second, after the upper cover, middle cylinder, and lower cover are stacked, they form independent gas storage chambers. After the gas storage chambers are interconnected through through holes, the upper cover, middle cylinder, and lower cover are also connected. This is equivalent to reinforcing the entire internal structure of the gas tank, giving it higher structural strength. Third, during the secondary injection molding, nitrogen gas at 7MPa-12MPa is injected into the gas storage cavity to pressurize the internal structure of the gas tank, preventing excessive pressure during secondary injection molding that could cause deformation. Nitrogen pressurization is also beneficial because of its high compressibility and stability; compared to air or water injection, nitrogen pressurization is faster, improving production efficiency. Fourth, another layer of tank body is injection molded onto the outer wall of the internal gas tank, increasing the overall wall thickness and structural strength of the plastic gas storage tank, resulting in better overall integrity. This allows for the manufacture of larger plastic gas storage tanks, enabling large-capacity gas storage. Attached Figure Description

[0011] Figure 1 This is a three-dimensional schematic diagram of a plastic gas storage tank according to the present invention; Figure 2 This is a schematic diagram of the structure of a plastic gas storage tank according to the present invention; Figure 3 It is a three-dimensional schematic diagram of the combined state of the upper main body, middle main body, and lower main body; Figure 4 It is a three-dimensional schematic diagram showing the disassembled state of the upper main body, middle main body, and lower main body; Figure 5 yes Figure 4 A magnified view of part A; Figure 6 This is a three-dimensional schematic diagram of the main body. Detailed Implementation

[0012] This invention relates to a plastic gas storage tank, such as... Figure 1 — Figure 6As shown, the system includes an upper body 1, a middle body 2, a lower body 3, and a tank 4, all made of PA6 or PA12 material. The upper body 1 consists of four or more upper covers 11, with an inlet / outlet valve 12 installed on one of the upper covers 11. Upper baffles 13 are installed between the upper covers 11. The middle body 2 is located below the upper body 1. The middle body 2 consists of four or more middle cylinders 21, with the upper opening of each middle cylinder 21 corresponding to the lower opening of each upper cover 11. The lower body 3 is located below the middle body 2. The body 3 is composed of four or more lower covers 31, with a lower baffle 32 between each lower cover 31. The upper opening of the lower cover 31 corresponds to the lower opening of the middle cylinder 21. The upper body 1, middle body 2 and lower body 3 are stacked one on top of the other. Each corresponding upper cover 11, middle cylinder 21 and lower cover 31 forms a gas storage chamber 5. Each gas storage chamber 5 has a through hole 51. The outer walls of the upper, middle and lower bodies 1, 2 and 3 are covered by a tank body 4. The upper part of the gas inlet and outlet valve 12 passes through the tank body 4.

[0013] Furthermore, the aforementioned middle body 2 is in one or more groups, with each group of middle body 2 stacked vertically, and the middle cylinder 21 of each group of middle body 2 stacked vertically. Each middle cylinder 21 of each group of middle body 2 can be designed to a specified height. Under the premise of ensuring structural strength, multiple groups of middle body 2 can be stacked according to the gas storage capacity requirements of the plastic gas storage tank. The higher the stack, the larger the gas storage chamber 5, and the greater the gas storage capacity.

[0014] Furthermore, a positioning insertion structure is provided between the upper cover 11 and the middle cylinder 21, between the stacked middle cylinders 21, and between the middle cylinder 21 and the lower cover 31. When the upper cover 11 is stacked with the topmost middle cylinder 21, when the upper middle cylinder 21 is stacked with the lower middle cylinder 21, and when the bottommost middle cylinder 21 is stacked with the lower cover 31, the positioning insertion structures ensure accurate positioning during stacking and assembly, which is beneficial for subsequent welding work and prevents misalignment during welding, thus preventing gaps.

[0015] Furthermore, the positioning and insertion structure includes positioning ribs 52 respectively provided at the lower openings of the upper cover 11 and the middle cylinder 21, positioning rings 53 respectively provided at the upper openings of the middle cylinder 21 and the lower cover 31, positioning grooves 54 provided in the positioning rings 53, and positioning ribs 52 and positioning grooves 54 being positioned and inserted into each other. On the one hand, the positioning ribs 52 and positioning rings 53 can increase the structural strength of the upper cover 11, the middle cylinder 21, and the lower cover 31, and prevent shrinkage caused by excessive injection pressure during secondary injection molding. On the other hand, when the lower opening of the upper cover 11 is stacked with the upper opening of the uppermost middle cylinder 21, the lower opening of the upper cover 11 is positioned and inserted into the positioning groove 54 of the upper opening of the middle cylinder 21 through the positioning ribs 52. When the middle cylinders 21 are stacked, the lower opening of the upper middle cylinder 21 is positioned and inserted into the positioning groove 54 of the upper opening of the lower middle cylinder 21 through the positioning ribs 52. When the lower opening of the lowermost middle cylinder 21 is stacked with the upper opening of the lower cover 31, the lower opening of the middle cylinder 21 is positioned and inserted into the positioning groove 54 of the upper opening of the lower cover 31 through the positioning ribs 52. The positioning between them is accurate and the assembly is convenient.

[0016] Furthermore, the inner wall of the middle cylinder 21 is provided with supporting ribs 23. The supporting ribs 23 can support the middle cylinder 21 and increase its structural strength, thus preventing shrinkage during secondary injection molding.

[0017] This invention also relates to a secondary injection molding filling and pressurization process for a plastic gas storage tank, the method comprising the following steps: ① First injection molding: Using PA6 or PA12 material, through three injection molds, the air inlet and outlet valve 12 is first placed in the first injection mold and the air inlet and outlet valve 12 is used as an insert for injection molding to obtain the upper body 1 with the air inlet and outlet valve 12. The upper body 1 is provided with four or more upper covers 11. The middle body 2 is obtained by injection molding from the second injection mold. The middle body 2 is provided with four or more middle cylinders 21. The lower body 3 is obtained by injection molding from the third injection mold. The lower body 3 is provided with four or more lower covers 31. Through holes 51 are opened on the side wall of the upper cover 1, the middle cylinder 21, or the lower cover 31. ② Welding connection: The upper body 1, one or more middle bodies 2 and lower body 3 are stacked one on top of the other. After the upper cover 11, middle cylinder 21 and lower cover 31 are stacked, an internal gas storage chamber 5 is formed. The upper cover 11, middle cylinder 21 and lower cover 31 are welded together by welding gun to obtain the inner gas tank 6. ③ Gas pressurization: Nitrogen gas at 7MPa-12MPa is injected into the gas storage chamber 5 through the inlet / outlet valve 12 by an air pump; ④ Secondary injection molding: The pressurized inner gas tank 6 is placed as an insert into the fourth injection mold, and a layer of tank body 4 is injected into the outer wall of the inner gas tank 6 to obtain the plastic gas storage tank 7. ⑤ Exhaust: Nitrogen gas in plastic gas storage tank 7 is extracted through inlet / outlet valve 12 using an air pump.

[0018] This invention discloses a plastic gas storage tank and its secondary injection molding filling and pressurization process. First, using PA6 or PA12 material, an upper body 1, a middle body 2, and a lower body 3 are manufactured using three injection molds. The upper body 1 consists of four or more upper covers 11, which can be designed as cylindrical. Each upper cover 11 can be fitted together adjacently to form a single unit, creating gaps between the cylindrical upper covers 11. An upper baffle 13 is installed at the top of each upper cover 11 within these gaps. One or two air inlet / outlet valves 12 are installed on the top of one of the upper covers 11. During injection molding, the air inlet / outlet valves 12 can be directly inserted into the mold as inserts and integrally molded with the upper body 1. The middle body 2 consists of four or more middle cylinders 21, which can also be designed as cylindrical. The middle cylinder 21 corresponds to the upper cover 11. Each middle cylinder 21 can be fitted together in all directions to form a whole. Gaps are formed between the cylindrical middle cylinders 21. The lower body 3 consists of four or more lower covers 31. Each lower cover 31 can be designed as a cylinder. The lower cover 31 corresponds to the middle cylinder 21. Each lower cover 31 can be fitted together in all directions to form a whole. Gaps are formed between the cylindrical lower covers 31. A lower baffle 32 is set at the bottom of each lower cover 31 in the gap. After the upper body 1, middle body 2, and lower body 3 are injection molded, the upper body 1, middle body 2, and lower body 3 are stacked one on top of the other. The lower opening of the upper cover 11 of the upper body 1 corresponds to the upper opening of the middle cylinder 21 of the uppermost middle body 2, and they are interlocked through a positioning and insertion structure. When there are two or more sets of the main body 2, the lower opening of the middle cylinder 21 of the first set of the main body 2 corresponds to the upper opening of the middle cylinder 21 of the second set of the main body 2, and they are interlocked through a positioning and insertion structure. The lower opening of the middle cylinder 21 of the second set of the main body 2 corresponds to the upper opening of the middle cylinder 21 of the third set of the main body 2, and they are interlocked through a positioning and insertion structure. This process is repeated until the lower opening of the middle cylinder 21 of the last set of the main body 2 corresponds to the upper opening of the lower cover 31 of the lower main body 3, and they are interlocked through a positioning and insertion structure. A gas storage cavity 5 is formed between the corresponding upper cover 11, middle cylinder 21, and lower cover 31. Through holes 51 are opened between each gas storage cavity 5 (which can be opened on the side wall of each adjacent upper cover 11, the side wall of each adjacent middle cylinder 21, or the side wall of each adjacent lower cover 31). A through-hole 51 (which can be formed directly during injection molding) is provided to connect the various gas storage chambers 5. After assembly, the various mating joints are welded together using a welding gun to ensure the airtightness of the gas storage chambers 5, resulting in an inner gas tank 6. Then, nitrogen is injected into one of the gas storage chambers 5 through the inlet / outlet valve 12 using an air pump. The nitrogen then enters each of the interconnected gas storage chambers 5 through the through-hole 51 until the gas pressure inside the inner gas tank 6 reaches 7MPa-12MPa. At this point, the nitrogen-filled inner gas tank 6 is placed as an insert into the fourth injection mold (or the inner gas tank 6 can be placed into the fourth injection mold first, and then nitrogen can be injected). The mold is closed, and a tank body 4 is injection molded onto the outer wall of the inner gas tank 6 through the fourth injection mold, resulting in a plastic gas storage tank 7.Finally, all nitrogen gas in the gas storage chamber 5 can be extracted using an air pump. This solution describes a plastic gas storage tank and its secondary injection molding, filling, and pressurization process. First, the upper body 1, middle body 2, and lower body 3 are individually injection molded. Then, the upper, middle, and lower bodies 1, 2, and 3 are stacked and welded together. The upper, middle, and lower bodies 1, 2, and 3 are manufactured separately. Supporting ribs and reinforcing ribs can be arranged inside the upper cover 11, middle cylinder 21, and lower cover 31. This facilitates core pulling and demolding, and, while ensuring structural strength, allows for the stacking of different numbers of middle bodies 2 to manufacture plastic gas storage tanks of varying heights and storage capacities, meeting diverse needs and offering better versatility. Second, the stacking of the upper cover 11, middle cylinder 21, and lower cover 31 forms an independent gas storage chamber 5. After the gas storage chambers 5 are interconnected through the through holes 51, the upper cover 11, the middle cylinder 21, and the lower cover 31 act as a reinforcing structure inside the entire inner gas tank 6, giving the entire inner gas tank 6 a higher structural strength. Third, during the secondary injection molding, nitrogen gas at 7MPa-12MPa is injected into the gas storage chambers 5 to pressurize the inside of the inner gas tank 6, preventing excessive secondary injection pressure that could cause deformation of the inner gas tank 6. Nitrogen gas pressurization is used because of its high compressibility and stability; compared to pressurization with air or water, nitrogen pressurization is faster, improving production efficiency. Fourth, another layer of tank body 4 is injection molded onto the outer wall of the inner gas tank 6, increasing the wall thickness and structural strength of the entire plastic gas storage tank 7, resulting in better overall integrity.

Claims

1. A plastic gas storage tank, characterized in that: The container comprises an upper body (1), a middle body (2), a lower body (3), and a tank (4) made of PA6 or PA12 material. The upper body (1) consists of four or more upper covers (11), with an inlet / outlet valve (12) installed on one of the upper covers (11). An upper baffle (13) is installed between each upper cover (11). The middle body (2) is located below the upper body (1). The middle body (2) consists of four or more middle cylinders (21). The upper opening of the middle cylinder (21) is connected to the upper cover (11). The lower body (3) is provided below the middle body (2) corresponding to the lower opening of the upper body (1), the middle body (2) is composed of four or more lower covers (31), and a lower baffle (32) is provided between each lower cover (31). The upper opening of the lower cover (31) corresponds to the lower opening of the middle cylinder (21). The upper body (1), the middle body (2) and the lower body (3) are stacked on top of each other. Each corresponding upper cover (11), middle cylinder (21) and lower cover (31) forms a gas storage chamber (5). A through hole (51) is provided between the gas storage chambers (5). A tank body (4) is covered on the outer walls of the upper body (1), middle body (2), and lower body (3). The upper part of the gas inlet and outlet valve (12) passes through the tank body (4). The middle body (2) consists of one or more groups, with each group of middle bodies (2) stacked vertically. The middle cylinders (21) of each group of middle bodies (2) are stacked vertically. A positioning and insertion structure is provided between the upper cover (11) and the middle cylinders (21). The stacked middle cylinders (21) are connected vertically. A positioning insertion structure is provided between the upper cover (11) and the lower cover (31). The positioning insertion structure includes positioning ribs (52) respectively provided at the lower opening of the upper cover (11) and the lower cover (21), positioning rings (53) respectively provided at the upper opening of the middle cylinder (21) and the lower cover (31), positioning grooves (54) provided in the positioning rings (53), positioning ribs (52) and positioning grooves (54) being positioned and inserted into each other, and support ribs (23) provided on the inner wall of the middle cylinder (21).

2. A method for secondary injection molding, filling, and pressurizing a plastic gas storage tank, wherein the method employs the plastic gas storage tank as described in claim 1, characterized in that... The method includes the following steps: ① First injection molding: PA6 or PA12 material is used. Through three injection molds, the air inlet and outlet valve (12) is first placed in the first injection mold. The air inlet and outlet valve (12) is used as an insert for injection molding to obtain the upper body (1) with the air inlet and outlet valve (12). The upper body (1) is provided with four or more upper covers (11). The middle body (2) is obtained by injection molding from the second injection mold. The middle body (2) is provided with four or more middle cylinders (21). The lower body (3) is obtained by injection molding from the third injection mold. The lower body (3) is provided with four or more lower covers (31). Through holes (51) are opened on the side wall of the upper cover (11), middle cylinder (21), or lower cover (31). ② Welding connection: The upper body (1), one or more middle bodies (2) and the lower body (3) are stacked one on top of the other. After the upper cover (11), the middle cylinder (21) and the lower cover (31) are stacked, an air storage chamber (5) is formed inside. The connection between the upper cover (11), the middle cylinder (21) and the lower cover (31) is welded with a welding gun to obtain the inner air tank (6). ③ Gas pressurization: Nitrogen gas at 7MPa-12MPa is injected into the gas storage chamber (5) through the inlet and outlet valves (12) by a gas pump; ④ Secondary injection molding: The pressurized inner gas tank (6) is placed as an insert into the fourth injection mold, and a layer of tank body (4) is injected into the outer wall of the inner gas tank (6) to obtain a plastic gas storage tank (7). ⑤ Exhaust: Nitrogen gas in the plastic gas storage tank (7) is extracted through the inlet and outlet valves (12) by a vacuum pump.

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