Plastic inner container of high-pressure gas cylinder and forming method therefor

Abstract

A plastic inner container of a high-pressure gas cylinder and a forming method therefor. The plastic inner container comprises a head sealing section (4), a cylinder body section (3) and a tail sealing section (2). The head sealing section (4) is composed of a head sealing section plastic shell, a sealing member and a head sealing section metal valve seat (5); the cylinder body section (3) is composed of a plastic shell; and the tail sealing section (2) is composed of a tail sealing section plastic shell and a tail sealing section metal valve seat (1), the tail sealing section metal valve seat (1) being injection-molded and embedded into the tail sealing section plastic shell by means of an insert.

Description

Plastic liner of high-pressure gas cylinder and molding method thereof Technical Field

[0001] The present invention relates to the technical field of hydrogen storage cylinders, and in particular to a plastic liner of a high-pressure cylinder and a molding method thereof. Background Art

[0002] Hydrogen fuel cell vehicles have seen rapid growth in recent years, and the hydrogen storage cylinder, a core component, has a decisive impact on vehicle range. To achieve higher volume-to-weight ratios and storage density, composite gas cylinders with plastic liner components are becoming a trend. Commonly used injection-molded and welded plastic liner components utilize a secondary assembly connection between the plastic shell and metal valve seat at both the head and tail sections of the liner. The gap between the plastic shell and metal valve seat requires a sealant.

[0003] Summary of the Invention

[0004] The purpose of the present invention is to provide a plastic liner for a high-pressure gas cylinder and a molding method thereof to solve the problems existing in the above-mentioned prior art. The tail sealing section has a simple structure, and the plastic shell and the metal valve seat are integrally molded by injection molding, which can reduce one sealing structure. At the same time, the tail sealing valve seat has a simple structure, which can reduce the weight of the gas cylinder and improve the hydrogen storage density of the gas cylinder.

[0005] To achieve the above object, the present invention provides the following solution: The present invention provides a plastic liner for a high-pressure gas cylinder, comprising

[0006] A head section, comprising a head section plastic shell and a head section metal valve seat, wherein the head section plastic shell comprises an integrally injection-molded arched end portion and a straight cylindrical section, the head section metal valve seat being press-fitted into the opening of the arched end portion, the head section metal valve seat being provided with one or more sealing grooves, wherein a retaining ring and an O-ring are provided in the sealing grooves; and

[0007] The tail section, the straight section of the head section and the tail section are welded together, the tail section comprises a tail section plastic shell and a tail section metal valve seat, and the tail section metal valve seat is integrally injection molded on the tail section plastic shell by insert.

[0008] Preferably, a metal support ring is embedded in the opening of the arched end, and a plurality of grooves are evenly distributed around the bottom of the metal support ring.

[0009] Preferably, the materials of the head section plastic shell and the tail section plastic shell are both thermoplastic plastic.

[0010] Preferably, the thermoplastic plastic is one of PA, PE or EVOH.

[0011] Preferably, it further comprises a barrel section, and both ends of the barrel section are respectively welded to the head section and the tail section.

[0012] Preferably, the barrel section is formed by injection molding or extrusion.

[0013] The present invention also provides a method for forming a plastic liner of a high-pressure gas cylinder, which is applied to the plastic liner of the high-pressure gas cylinder, comprising the following steps:

[0014] Step 1: Forming the sealing section. Before injection molding, a cylindrical positioning tool is installed on the metal valve seat of the sealing section through threads. The middle position of the cylindrical positioning tool has a full circle groove;

[0015] Step 2: Place the metal valve seat of the sealing tail section together with the installed cylindrical positioning tool into the positioning hole of the mold, ensuring that the cylindrical positioning tool is completely immersed in the positioning hole;

[0016] Step 3: After the mold is closed, the side oil cylinder advances the core, driving the positioning pin to insert into the groove in the middle position of the cylindrical positioning tooling, and the metal valve seat of the sealing tail section is positioned through the cylindrical positioning tooling;

[0017] Step 4: Injecting the injection molding material into the mold cavity through the runner;

[0018] Step 5: After the injection molding is completed, the side oil cylinder retracts the core, driving the positioning pin to disengage the groove in the middle position of the cylindrical positioning tooling;

[0019] Step 6: After the mold is opened, push the movable mold push plate from the back to the front to push out the formed plastic liner to complete the demoulding;

[0020] Step 7: The plastic shell of the head section is injection molded. A metal support ring is provided at the sealing portion of the arched end of the plastic shell of the head section during the molding stage. The bottom of the metal support ring has several grooves.

[0021] Step 8: The metal valve seat of the head section is pressed into the injection-molded plastic shell of the head section by press-fitting; the metal valve seat of the head section has one or more sealing grooves, and a retaining ring and an O-ring are arranged in the sealing groove;

[0022] Step 9: Select three-stage or two-stage welding according to your needs. The three-stage welding includes the tail section, the barrel section and the head section; the two-stage welding includes the tail section and the head section;

[0023] Step 10: Use welding technology to form a welding seal on the welding surface. After welding is completed, remove the outer surface curling material after welding by machining to complete the plastic liner molding.

[0024] Compared with the prior art, the present invention has achieved the following beneficial technical effects:

[0025] The plastic liner of the high-pressure gas cylinder of the present invention and the molding method thereof, the plastic liner comprises a head section, a barrel section, and a tail section. The head section is composed of a plastic shell, a seal, and a metal valve seat, the barrel section is composed of a plastic shell, and the tail section is composed of a plastic shell and a metal valve seat, and the metal valve seat is embedded in the plastic shell of the tail section by insert injection molding. The tail section of the present invention has a simple structure, and the plastic shell and the metal valve seat are integrally molded by injection molding, which can reduce a sealing structure. At the same time, the tail valve seat has a simple structure, which can reduce the weight of the gas cylinder and increase the hydrogen storage density of the gas cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] FIG1 is a schematic diagram of the overall structure of the plastic liner of a high-pressure gas cylinder;

[0028] Figure 2 is a schematic diagram of the connection position between the metal valve seat of the head section and the plastic shell;

[0029] FIG3 is a schematic structural diagram of a metal support ring;

[0030] Figure 4 is a schematic diagram of the connection between the metal valve seat of the sealing tail section and the cylindrical positioning fixture;

[0031] Figure 5 shows the state after the mold is closed, when the side oil cylinder advances the core, driving the positioning pin to insert into the groove in the middle position of the cylindrical positioning tool;

[0032] Among them, 1. Metal valve seat of the tail section; 2. Tail section; 3. Cylinder section; 4. Head section; 5. Metal valve seat of the head section; 6. Metal support ring; 7. First sealing ring; 8. Second sealing ring. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] The present invention aims to provide a plastic liner for high-pressure gas cylinders and a molding method for the same, with applications in the field of high-pressure gas cylinder plastic liner molding. The liner's head section consists of a conventional plastic shell, seals, and a metal valve seat, while the tail section is integrally molded with a metal valve seat insert. The liner's head section, barrel section, and tail section are welded together to form a complete liner. This invention reduces the weight of the metal valve seat in the tail section, increasing hydrogen storage density while also eliminating one seal and reducing hydrogen leakage paths.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] As shown in Figures 1-5, the present invention provides a plastic liner for a high-pressure gas cylinder, comprising one or two circumferential welded joints. A liner with one welded joint is formed by welding a tail section 2 and a head section 4. A liner with two welded joints is formed by welding a tail section 2, a barrel section 3, and a head section 4.

[0037] The tail section 2 consists of a plastic shell and a metal valve seat 1 directly molded by injection molding; the barrel section 3 is formed by injection molding or extrusion; the head section 4 consists of a plastic shell with an embedded metal ring at the mouth, a press-in metal valve seat with one or more sealing grooves, and corresponding sealing rings in the sealing grooves (two sealing rings are provided as shown in Figure 2, namely the first sealing ring 7 and the second sealing ring 8) and a retaining ring.

[0038] In one embodiment, the materials of the plastic shell of the head section and the plastic shell of the tail section are both thermoplastic plastic.

[0039] In one embodiment, the thermoplastic is one of PA, PE or EVOH.

[0040] A molding process for a plastic liner of a high-pressure gas cylinder comprises the following steps:

[0041] S1, the sealing tail section 2 is formed. Before injection molding, a cylindrical positioning tool is installed on the metal valve seat 1 of the sealing tail section through threads. The middle position of the cylindrical positioning tool has a full circle groove.

[0042] S2. Place the sealing end metal valve seat 1 together with the installed cylindrical positioning tool into the positioning hole of the mold, ensuring that the cylindrical positioning tool is completely immersed in the positioning hole.

[0043] S3. After the mold is closed, the side oil cylinder advances the core, driving the positioning pin to insert into the groove in the middle position of the cylindrical positioning tooling, and the metal valve seat 1 of the sealing tail section is positioned through the cylindrical positioning tooling.

[0044] S4. Inject the molding material into the mold cavity through the runner.

[0045] S5. After the injection molding is completed, the side oil cylinder retracts the core, driving the positioning pin to disengage the groove in the middle position of the cylindrical positioning tooling.

[0046] S6. After the mold is opened, the movable mold push plate is pushed forward from the back to push out the formed plastic shell of the tail section to complete the demoulding.

[0047] S7, the inner shell of the head section 4 is formed by injection molding. The head section 4 consists of a round arch end and a straight cylindrical section. A metal support ring 6 is set at the sealing part of the head section 4 during the molding stage. The bottom of the metal support ring 6 has several grooves.

[0048] S8. The metal valve seat 5 of the head section is pressed into the injection molded head section by press fitting; the metal valve seat 5 of the head section has one or more sealing grooves on it, and a retaining ring and an O-ring are arranged in the sealing groove.

[0049] S9. The middle barrel section 3 is formed by injection molding or extrusion.

[0050] S10. Select three-stage or two-stage welding as needed. The three-stage welding includes: tail section 2, barrel section 3, and head section 4; the two-stage welding includes: tail section 2 and head section 4.

[0051] S11. Use welding technology to form a welding seal on the welding surface. After welding is completed, remove the outer surface curling material after welding by machining to complete the inner liner forming.

[0052] The advantages of the plastic liner of the high-pressure gas cylinder of the present invention are as follows:

[0053] Increasing the hydrogen storage density of the gas cylinder and reducing the hydrogen permeation of the gas cylinder can reduce the size and weight of the metal valve seat in the tail section. The entire gas cylinder only has one seal at the press-fitting part of the metal valve seat in the head section, reducing hydrogen leakage.

[0054] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all perspectives, the embodiments should be regarded as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description. It is intended that all changes that fall within the meaning and range of equivalents of the claims be included in the present invention, and any reference signs in the claims should not be construed as limiting the claims to which they relate.

[0055] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A plastic inner liner for a high-pressure gas cylinder, characterized in that: including a head section, the head section including a head-section plastic housing and a head-section metal seat, the head-section plastic housing including an integrally injection-molded arched end and a straight cylinder section, the head-section metal seat being press-fitted into an opening of the arched end, one or more sealing grooves being provided on the head-section metal seat, and a retaining ring and an O-ring being provided in the sealing grooves; and a tail section, the straight cylinder section of the head section being welded to the tail section, the tail section including a tail-section plastic housing and a tail-section metal seat, the tail-section metal seat being integrally injection-molded with an insert at the tail-section plastic housing.

2. The plastic inner liner of the high-pressure gas cylinder according to claim 1, characterized in that: A metal support ring is embedded in the opening of the arched end, and a plurality of grooves are circumferentially and uniformly provided at the bottom of the metal support ring.

3. The plastic inner liner of the high-pressure gas cylinder according to claim 1, characterized in that: The materials of the head-section plastic housing and the tail-section plastic housing are both thermoplastic plastics.

4. The plastic inner liner of the high-pressure gas cylinder according to claim 3, characterized in that: The thermoplastic plastic is one of PA, PE or EVOH.

5. The plastic inner liner of the high-pressure gas cylinder according to claim 1, characterized in that: It further includes a cylinder section, and two ends of the cylinder section are respectively welded to the head section and the tail section.

6. The plastic inner liner of the high-pressure gas cylinder according to claim 5, characterized in that: The cylinder section is formed by injection molding or extrusion molding.

7. A forming method for a plastic inner liner of a high-pressure gas cylinder, which is applied to the plastic inner liner of the high-pressure gas cylinder described in any one of claims 1-6, characterized in that, including the following steps: Step 1, forming the tail section. Before injection molding, a cylindrical positioning tooling is installed on the tail-section metal seat through threads, and a whole-circle groove is provided at the middle position of the cylindrical positioning tooling; Step 2, putting the tail-section metal seat together with the installed cylindrical positioning tooling into a positioning hole of a mold, ensuring that the cylindrical positioning tooling is completely immersed in the positioning hole; Step 3, after closing the mold, the side oil cylinder advances the core, driving a positioning pin to insert into the groove at the middle position of the cylindrical positioning tooling, and positioning the tail-section metal seat through the cylindrical positioning tooling; Step 4, injecting injection molding raw materials into the mold cavity through a runner; Step 5, after injection molding is completed, the side oil cylinder retracts the core, driving the positioning pin to disengage from the groove at the middle position of the cylindrical positioning tooling; Step 6, after opening the mold, pushing the moving mold push plate from back to front to push out the formed tail-section plastic housing to complete demolding; Step 7, the head-section plastic housing is formed by injection molding, and a metal support ring is provided at a sealing part of the arched end in the head-section plastic housing during the forming stage, and several grooves are provided at the bottom of the metal support ring; Step 8, the head-section metal seat is press-fitted into the injection-molded head-section plastic housing; there is one or more sealing grooves on the head-section metal seat, and a retaining ring and an O-ring are provided in the sealing grooves; Step 9, select three-stage or two-stage welding according to needs. The three-stage welding includes a tail section, a cylinder section and a head section; the two-stage welding includes a tail section and a head section; Step 10, adopting a welding process to form a welded seal on the welding surface. After welding is completed, remove the curled material on the outer surface after welding by machining to complete the forming of the plastic inner liner.

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