CN115405849A - A type IV hydrogen storage cylinder end sealing structure and preparation method thereof - Google Patents

Abstract

The invention relates to a type IV hydrogen storage cylinder end sealing structure and a preparation method thereof. The sealing structure mainly includes a metal inner and outer bottle mouth, a plastic liner and several sealing rings, wherein the metal inner bottle mouth is pre-embedded in the plastic liner in an integrated way, and the metal outer bottle mouth is fixed together with the metal inner bottle mouth through threads. And close to the plastic inner tank, the sealing ring is set in the annular groove between the metal outer bottle mouth and the plastic inner tank and is pressed by the metal outer bottle mouth, thereby realizing the reinforcement and sealing of the end of the gas cylinder inner tank. In addition, by setting gaps and grooves at specific parts of the metal inner bottle mouth, the connection reliability between the metal inner bottle mouth and the plastic liner is enhanced, and the molding quality of the transition part between the two is greatly improved. Compared with existing similar products, the gas cylinder provided by the invention has the advantages of simple structure, few parts, easy assembly, etc., the overall safety, reliability and durability of the gas cylinder have been significantly improved, and the market competitiveness is better.

Description

A type IV hydrogen storage cylinder end sealing structure and preparation method thereof

technical field

The invention relates to the technical field of pressure vessels and hydrogen energy, in particular to a type IV hydrogen storage cylinder end sealing structure and a preparation method thereof.

Background technique

Hydrogen storage technology is the key to the development of new energy vehicles. The development and application technology of traditional metal-lined type III gas cylinders is becoming more and more mature in my country. However, this type of gas cylinder has obvious shortcomings such as hydrogen embrittlement effect and poor fatigue performance, and there are huge obstacles when it is used as a vehicle-mounted hydrogen storage cylinder. In recent years, the plastic-lined IV gas cylinders, which have been gradually developed in recent years, provide a feasible idea for improving the hydrogen storage density, fatigue performance and hydrogen barrier performance of vehicle-mounted gas cylinders. In order to improve the overall rigidity, the two ends of the plastic liner of type IV gas cylinders usually use metal bottle mouth technology to meet the problem of fixing the liner in the subsequent winding process. Due to the obvious difference in the material of the metal bottle mouth and the plastic liner, the quality of the interface connection between the two becomes the key to determine the airtightness of the gas cylinder. In addition, the plastic head of the gas cylinder will be slightly deformed during the filling and deflation process, resulting in a gap between it and the metal bottle mouth, which is prone to hydrogen leakage and other problems, posing a major safety hazard. This problem has not been well received before. Good solution.

The search found that Chinese patent CN113464832A discloses a gas bottle mouth structure, a highly airtight hydrogen storage cylinder and its manufacturing method. The bottle mouth sealing structure includes a metal bottle mouth, a plastic head and fasteners, wherein the fasteners It includes a connecting part and a first flange, and a sealing groove with a first sealing ring is provided on the front end of the first flange; the metal bottle mouth is composed of a neck and a second flange, and the second flange is provided with several rings There are several notches at the front end of the second flange; after the plastic head that fills each notch and each annular groove and wraps the second flange and the rear section of the neck is formed by injection molding, the fastener is tightened on the internal thread paragraph. In addition, the proposal also discloses a highly airtight gas storage cylinder with such a bottle mouth structure and a manufacturing method thereof. The analysis shows that in this solution, the gas seal is mainly realized by the sealing ring on the fastener. However, when installing the fastener, it needs to be screwed in from the inner tank of the gas cylinder, which virtually increases the difficulty of manufacturing and assembly. In addition, this technology uses an injection molding process, and two plastic heads with a sealed structure need to be welded together with the cylinder body, which is not only cumbersome but also prone to defects such as bubbles at the weld.

Chinese patent CN113188039A discloses a plastic liner composite gas cylinder joint. The joint includes a joint body and a sealing ring. One end of the joint body is provided with an annular installation groove, and the installation groove is arranged between the inner and outer walls of the joint body. The installation groove is used for accommodating the bottle mouth of the gas cylinder liner and is in sealing contact with the inner and outer walls of the bottle mouth of the gas cylinder liner, and is fixedly connected, and the sealing ring is sleeved on the inner wall of the joint body. It can be seen from the analysis that the joint structure of the composite gas cylinder disclosed in this technology is relatively complicated, involving three types of installation cylinders: external, middle and internal, and there is no sealing device between each installation head and the plastic inner tank, and there is a large risk of leakage. In addition, this technology has not announced the specific molding process, and it is likely to have certain processing difficulties.

Similar technologies also include CN215061274U, CN214405590U, CN11377592 6A, etc. Most of these sealing structures are provided with a large number of sealing rings, sealing grooves, sealing steps and other structures, which greatly increase the complexity of the structure, manufacturing cost, and assembly difficulty.

Contents of the invention

The purpose of the present invention is to overcome the above-mentioned defects in the prior art, and provide a brand-new type IV hydrogen storage cylinder end sealing structure, which mainly includes a metal outer bottle mouth 1, a metal inner bottle mouth 2, and a plastic liner 3 , sealing ring 4, wherein the metal outer bottle mouth 1 includes a base 1-1 and an air nozzle 1-2, the metal inner bottle mouth 2 includes a base 2-1 and a hollow raised part 2-2; the metal inner bottle mouth base 2 -1 is pre-buried in the plastic liner 3, the hollow raised part 2-2 protrudes from the end of the plastic liner 3 and communicates with the outside world, the gas nozzle 1-2 of the metal outer bottle mouth is set in the hollow of the metal inner bottle mouth The raised part 2-2 is on, and the base 1-1 of the metal outer bottle mouth is close to the outer surface of the plastic liner 3, and the sealing ring 4 is fixed between the metal outer bottle mouth 1 and the plastic liner 3.

Further, the arc shape of the base 2-1 of the metal inner bottle mouth and the base 1-1 of the metal outer bottle mouth matches the shape of the end face of the plastic liner 3, and the upper and lower surfaces of the base 2-1 are completely embedded in the plastic In the liner 3, the diameter of the base 2-1 is equivalent to 10%-60% of the diameter of the plastic liner.

Further, on the inner surface of the air nozzle 1-2 of the metal outer bottle mouth and the outer surface of the hollow raised part 2-2 of the metal inner bottle mouth, there are mutually matched threads, and the metal outer bottle mouth 1 and the metal inner bottle mouth 2 pass through. Thread for a secure and airtight connection.

Further, coaxial grooves 2-3 and notches 2-4 are provided on the base 2-1 of the metal inner bottle mouth along the circumference. The structures such as grooves and gaps on the metal inner bottle mouth will be filled with molten plastic when the plastic inner container is injection-molded, thereby ensuring that the metal inner bottle mouth 2 is firmly embedded in the plastic inner container 3 and improving the bonding strength of the two and reliability.

Furthermore, the grooves 2-3 are arranged on the bottom surface of the metal inner bottle mouth base 2-1, and the number thereof is 1-5. The grooves 2-3 are discontinuous or continuous, preferably discontinuous.

Furthermore, the notches 2-4 are equidistantly distributed on the edge of the metal inner bottle mouth base 2-1, and the number of notches is 2-10.

Further, an annular groove 1-3 is provided on the bottom surface of the base 1-1 of the metal outer bottle mouth, and a matching annular groove is arranged on the outer surface of the end of the plastic liner 3, and the sealing ring 4 is fixed on the metal outer bottle mouth. 1 and the annular groove on the plastic liner 3, thereby realizing the sealing between the two.

Furthermore, the number of the sealing rings is 1-5.

Further, the materials of the metal outer bottle mouth 1 and the metal inner bottle mouth 2 are all selected from any one of iron, steel, aluminum or their alloys, and the material of the plastic liner 3 is selected from polypropylene (PP) , polyethylene (PE), nylon (PA) and other general-purpose plastics or engineering plastics, the material of the sealing ring is selected from butyl rubber, silicon rubber, fluorine rubber, EPDM rubber, neoprene Any one of rubber, acrylic rubber, natural rubber, and polyurethane rubber, and the cross-sectional shape of the sealing ring is any one of rectangle, V shape, U shape, O shape, and Y shape.

Another important object of the present invention is to provide a method for preparing the end sealing structure of the above-mentioned type IV hydrogen storage cylinder. The method includes the following steps: (a) first, fix the metal inner bottle mouth 2 in a mold, and process and shape it to obtain a pre-embedded metal inner bottle. The plastic liner 3 at the mouth of the bottle; (b) insert the sealing ring 4 into the annular groove on the outer surface of the end of the plastic liner 3, and then align the metal outer bottle mouth 1 with the metal inner bottle mouth 2 and tighten it.

Further, the molding process of the plastic liner 3 is selected from any one of blow molding, injection molding, rotational molding, and 3D printing, and the plastic particles used for molding must be placed at 55-65°C before use Drying to prevent defects such as holes in the plastic liner caused by water vapor during injection molding.

The third objective of the present invention is to provide a type IV hydrogen storage cylinder equipped with the above-mentioned end sealing structure.

The present invention makes a series of improvements to the end sealing structure of the existing gas cylinder, mainly including the following points:

(1) In order to improve the strength and reliability of the embedded bonding between the metal inner bottle mouth and the plastic inner container, the inventor has set a number of grooves and notches on the bottom surface and the edge of the metal inner bottle mouth respectively. Through these unique designs, the integrated The mechanical properties of the molded plastic liner, in addition, these grooves and notches not only significantly increase the gas leakage path and improve the airtightness of the gas cylinder, but also effectively solve the problem of fixing the plastic liner during the winding process, and can prevent the metal inner bottle mouth from Relative sliding with the plastic liner;

(2) In order to improve the strength and reliability of the end of the gas cylinder, the end of the plastic liner is equipped with a metal outer bottle mouth that is protected, reinforced, and convenient for gas circulation, and it is fixed on the metal inner bottle through a simple threaded connection On the mouth, the damage to the plastic liner is avoided through the connection between the metal parts;

(3) In order to prevent gas leakage caused by plastic deformation during inflation and deflation, an annular sealing ring is added between the contact surface of the metal outer bottle mouth and the plastic inner tank, thereby greatly improving the safety and reliability of the gas cylinder .

Compared with the existing similar gas cylinder products, the gas cylinder prepared according to the method of the present invention has the advantages of simple structure, easy production and assembly, high efficiency, etc., and also avoids defects such as bubbles caused by secondary welding, and greatly improves the performance of the gas cylinder. Overall safety, reliability and durability.

Description of drawings

Fig. 1 is the schematic sectional view of the end of type IV hydrogen storage cylinder of the present invention;

Fig. 2 is the sectional three-dimensional schematic diagram of the metal outer bottle mouth of the present invention;

Fig. 3 is the sectional perspective schematic diagram of the metal inner bottle mouth of the present invention;

Fig. 4 is the structural representation of sealing ring of the present invention;

Fig. 5 is a schematic cutaway perspective view of the plastic liner of the present invention.

1. Metal outer bottle mouth, 2. Metal inner bottle mouth, 3. Plastic liner, 4. Sealing ring, 1-1, base, 1-2, air nozzle, 1-3, annular groove, 2-1 , base, 2-2, hollow protrusion, 2-3, groove, 2-4, notch.

Detailed ways

In order to enable those skilled in the art to fully understand the technical solutions and beneficial effects of the present invention, further description will be given below in conjunction with specific embodiments and accompanying drawings.

Example 1

As shown in Figure 1-5, a composite type IV hydrogen storage cylinder has a special sealing structure at both ends, and the sealing structures at the left and right ends are the same. In some embodiments, such a sealing structure may also be provided only at one end of the gas cylinder. In order to further illustrate the problem, next, take any end of the gas cylinder (such as the left end) as an example for a detailed introduction.

The entire plastic liner 3 is connected with two metal outer bottle mouths 1, metal inner bottle mouths 2 and several sealing rings 4 with similar shapes and structures, wherein the metal inner bottle mouths 2 are preformed at the end of the plastic liner 3 in advance , the metal outer bottle mouth 1 and the sealing ring 4 are fixed on the plastic liner in the later stage. The inner surface of the gas nozzle 1-2 of the metal outer bottle mouth is provided with threads, and the outer surface of the hollow raised part 2-2 of the metal inner bottle mouth 2 similar to the gas nozzle is provided with matching threads, and the metal inner and outer bottle mouths pass through the threads. firmly connected together. An annular groove 1-3 is arranged on the bottom surface of the circular base 1-1 of the metal outer bottle mouth 1, and an annular groove 1-3 of the same shape and number is arranged on the outer surface of the end of the plastic liner 3, and the sealing ring 4 is fixed on the In the annular groove and pressed tightly by the metal outer bottle mouth 1. After being installed in place, the metal outer bottle mouth 1 and the plastic liner 3 intersect or contact with each other smoothly, without steps or grooves.

In another preferred embodiment of the present invention, there are several notches 2-4 evenly distributed at a certain distance from the edge of the base 2-1 of the plastic inner bottle mouth, and several gaps 2-4 are arranged on the bottom surface of the base 2-1. (Can also be continuous) groove 2-3. This design can avoid the problem of relative sliding and misalignment between the metal inner bottle mouth and the plastic liner 3 during molding, improves the reliability of the combination of the two, and also solves the problem of fixing the liner when the carbon fiber is wound later.

In order to ensure the quality of gas cylinder products, we developed and optimized the following preparation process:

① Raw material pretreatment: Put the granular high-density polyethylene resin raw material in an oven, heat to 60±2°C and bake for 1±0.2 hours to remove moisture as much as possible, and put the dried resin into the hopper for later use.

②Injection molding of plastic liner: Fix the metal inner bottle mouth 1 at the corresponding position of the mold, start the rotational molding machine, inject molten plastic into the mold cavity and fully fill the various grooves, gaps and mold cavities of the metal inner bottle mouth 2, cool off After molding, the left half inner tank is obtained; the right half inner tank is molded according to the same method, and then the left and right inner tanks are welded together to obtain a complete gas cylinder inner tank. Welding methods can be ultrasonic welding, friction welding, hot plate welding and so on.

③Plastic liner assembly: insert the rubber sealing ring 4 into the annular groove on the outer surface of the semi-finished plastic liner prepared in the previous step in advance, and then align the metal outer bottle mouth 1 with the metal inner bottle mouth 2, Then turn the metal outer bottle mouth 1 and make it screw on the metal inner bottle mouth 2, thus completing the assembly.

Claims (10)

1. A type IV hydrogen storage cylinder end sealing structure, characterized in that: the sealing structure includes a metal outer bottle mouth (1), a metal inner bottle mouth (2), a plastic liner (3), and a sealing ring (4) , wherein the metal outer bottle mouth (1) includes a base (1-1) and an air nozzle (1-2), and the metal inner bottle mouth (2) includes a base (2-1) and a hollow raised portion (2-2); The base (2-1) is pre-embedded in the plastic liner (3), the hollow protrusion (2-2) protrudes from the end of the plastic liner (3) and communicates with the outside world, and the air nozzle (1-2) Set on the hollow raised part (2-2) and the base (1-1) is close to the outer surface of the plastic liner (3), the sealing ring (4) is fixed on the metal outer bottle mouth (1) and the plastic liner (3) )between. 2. The end sealing structure of type IV hydrogen storage cylinder according to claim 1, characterized in that: the base (2-1), the arc shape of the base (1-1) and the end face shape of the plastic liner (3) match, and the upper and lower surfaces of the base (2-1) are completely embedded in the plastic liner (3), and the diameter of the base (2-1) is equivalent to 10%-60% of the diameter of the plastic liner (3) . 3. The end sealing structure of type IV hydrogen storage cylinder according to claim 1, characterized in that: the inner surface of the gas nozzle (1-2) and the outer surface of the hollow raised part (2-2) are provided with mutually matching thread, the metal outer bottle mouth (1) is fixedly connected with the metal inner bottle mouth (2) through threads. 4. The type IV hydrogen storage cylinder end sealing structure according to claim 1, characterized in that: coaxial grooves (2-3) and notches (2-3) are provided along the circumference on the base (2-1) -4), wherein the groove (2-3) is arranged on the bottom surface of the base (2-1), the number is 1-5, and the groove (2-3) is intermittent or continuous; the gap (2- 4) Equidistant discontinuities are distributed on the edge of the base (2-1), the number of which is 2-10. 5. The end sealing structure of type IV hydrogen storage cylinder according to claim 1, characterized in that: an annular groove (1-3) is arranged on the bottom surface of the base (1-1), and a plastic liner (3) The outer surface of the end part is provided with a matching annular groove, and the sealing ring (4) is fixed in the annular groove on the metal outer bottle mouth (1) and the plastic liner (3). 6. The type IV hydrogen storage cylinder end sealing structure according to claim 1, characterized in that: the materials of the metal outer bottle mouth (1) and the metal inner bottle mouth (2) are all selected from iron, steel, aluminum Any one of its alloys, the material of the plastic liner (3) is selected from any one of PP, PE, PA and other general-purpose plastics or engineering plastics, and the material of the sealing ring is selected from butyl rubber , silicone rubber, fluorine rubber, EPDM rubber, neoprene rubber, acrylic rubber, natural rubber, polyurethane rubber, the cross-sectional shape of the sealing ring is rectangular, V-shaped, U-shaped, O-shaped , any one of Y shapes. 7. The preparation method of the type IV hydrogen storage cylinder end sealing structure according to any one of claims 1-6, characterized in that the method comprises the following steps: (a) first fix the metal inner bottle mouth (2) in the mould, and process and form the plastic inner container (3) to obtain the pre-embedded metal inner bottle mouth; (b) Snap the sealing ring (4) into the annular groove on the outer surface of the end of the plastic liner (3), and then align the metal outer bottle mouth (1) with the metal inner bottle mouth (2) and tighten. 8. The method according to claim 7, characterized in that: the molding process of the plastic liner (3) is selected from any one of blow molding, injection molding, rotational molding, and 3D printing molding. 9. The method according to claim 7 or 8, characterized in that the plastic granules used for molding need to be fully dried at 55-65°C before use. 10. A type IV hydrogen storage gas cylinder, characterized in that the gas cylinder is equipped with the end sealing structure according to any one of claims 1-7.

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