Pressure vessel with improved airtightness

Abstract

Disclosed is a pressure vessel with improved airtightness. The pressure vessel according to an embodiment of the present invention uses an energizer seal as a sealing structure, and thus prevents leakage of high-pressure gas occurring in a gap between a boss and a liner and may have strong durability.

Description

Pressure vessels with improved airtightness

[0001] The present invention relates to pressure vessel technology, and more particularly, to technology for ensuring airtightness so that high-pressure gas stored in a pressure vessel does not leak.

[0002] This invention is the result of the Future Vehicle Battery System Core Component Development Support Project, supported by Gyeongsangbuk-do and Yeongcheon-si and managed by Gyeongbuk Hybrid Parts Research Institute, and the Development of High-Pressure Storage Containers with a Hydrogen Weight Ratio of 6.0% or More and Reliability Verification Technology through Process Improvement (Organization: Shinyoung Co., Ltd., Research Period: March 1, 2024 - November 30, 2024, Contribution Ratio 1 / 1).

[0003] Pressure vessels used in fuel cell vehicles and other vehicles must be lightweight, compact, and safe, as they are installed inside the vehicle. These pressure vessels must not only maintain a high specific strength for the entire vessel, but also exhibit high elastic strength to maintain airtightness against high-pressure gases and to withstand high pressures of up to 700 bar and a burst pressure of 1,570 bar. This is because while specific strength is an important indicator of the vessel's ability to withstand temporary excessive charging pressure or external impacts on a portion of the vessel while maintaining the same weight, the vessel must also not leak the high-pressure gas within it, even if the vessel deforms repeatedly during charging and discharging.

[0004] Meanwhile, pressure vessels are classified into Types 1 and 2, which have bodies made of steel; Type 3, which consists of an aluminum liner and a carbon composite outer covering; and Type 4, which consists of a polymer liner and a carbon composite outer covering. Of these, Type 4 vessels, in particular, are required to have robust sealing performance during charging and discharging, as they are used repeatedly in high-pressure environments exceeding 700 bar, and seals are used to prevent leakage of high-pressure gas.

[0005] According to one embodiment, a pressure vessel with improved airtightness is proposed to prevent leakage of stored high-pressure gas.

[0006] According to one embodiment, a pressure vessel is provided in a cylindrical shape, has a through hole formed in the central portion along the vertical direction, and includes a boss integrally extending radially outward along the circumference direction at the lower portion, a liner having a shape of the pressure vessel and forming a receiving space communicating with the through hole so that gas is received therein, and an upper portion thereof is joined along a lower surface of the boss, and a sealing portion hermetically joined at a boundary area between the boss and the liner so as to block leakage of gas received in the receiving space, wherein the sealing portion is an energizer seal.

[0007] The sealing portion may include a main seal forming a body and having a receiving portion on one side thereof, a backup ring positioned on at least one side of the main seal to hold the position of the main seal, a ring drop prevention portion provided as a catch body to prevent the backup ring from falling off, and a spring provided on the receiving portion of the main seal to ensure that the main seal is in close contact and to spread as the pressure inside the pressure vessel increases.

[0008] The pressure vessel includes a sealing fastening portion for fastening a sealing portion, wherein the sealing fastening portion has a step between the boss and the liner, and a step shape between the injection mold and the boss can be created so that a burr does not occur on the liner during liner injection molding.

[0009] The liner may include an undercut processing portion to prevent lifting at the joint between the boss and the liner when shrinkage of the liner material occurs.

[0010] The pressure vessel may further include a locker that fastens the sealing portion with a tolerance to prevent the sealing portion from coming off but does not come into direct contact with the sealing portion.

[0011] A pressure vessel with improved airtightness according to one embodiment can prevent leakage of high-pressure gas occurring at a gap between a boss and a liner of the pressure vessel.

[0012] In particular, by using an energizer seal as the sealing structure, it can have strong durability in an environment where high-pressure gas of 700 bar is repeatedly charged and discharged at temperatures of -40 to +85 degrees and used for a long period of time.

[0013] Since the locker forming the pressure vessel may be damaged by wear or other factors when it comes into contact with the sealing portion, the locker is fastened with a tolerance between it and the sealing portion to avoid direct contact, thereby preventing the sealing portion from coming off.

[0014] The sealing portion of the energizer seal structure has a backup ring to disperse the pressure applied to the sealing portion, reduce wear of the sealing portion, and prevent gap extrusion.

[0015] The sealing portion of the energizer seal structure can prevent the backup ring from falling off due to friction when the sealing portion is installed by having a ring fall-off prevention portion equipped with a catch body to prevent the backup ring from falling off.

[0016] By forming a sealing joint having a step between the boss and the liner but no step between the injection mold of the liner and the boss, and by fastening the sealing joint to the sealing joint, the problem of lifting and gap extrusion occurring due to shrinkage of the high molecular polymer, which is the liner material, after liner injection can be solved, and the problem of burr occurrence occurring when there is a step between the injection mold of the liner and the boss can be solved.

[0017] Figure 1 is a drawing illustrating a pressure vessel according to one embodiment of the present invention;

[0018] Figure 2 is a drawing showing a sealing part fastened according to one embodiment of the present invention.

[0019] Figure 3 is a drawing showing a gas leakage path according to one embodiment of the present invention;

[0020] Figure 4 is a drawing showing a pressure vessel equipped with a sealing portion according to one embodiment of the present invention;

[0021] Figure 5 is a drawing showing the detailed structure of a sealing portion according to one embodiment of the present invention;

[0022] FIG. 6 is a drawing illustrating the structure of a sealing fastener according to one embodiment of the present invention.

[0023] The advantages and features of the present invention, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided only to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Like reference numerals designate like elements throughout the specification.

[0024] In describing embodiments of the present invention, if it is determined that a specific description of a known function or configuration may unnecessarily obscure the gist of the present invention, such detailed description will be omitted. The terms described below are terms defined to reflect functions in embodiments of the present invention, and these may vary depending on the intention or custom of the user or operator. Therefore, the definitions should be made based on the contents throughout this specification.

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments of the present invention exemplified below may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

[0026] FIG. 1 is a drawing illustrating a pressure vessel according to one embodiment of the present invention.

[0027] Referring to FIG. 1, the pressure vessel (1) includes a boss (11), a liner (12), a sealing unit (13), a locker (14), and a composite material layer (15).

[0028] A pressure vessel (1) is a vessel for storing high-pressure gas, and is manufactured by forming an interior and reinforcing the exterior with composite materials. The pressure vessel (1) may be a vessel for storing fuel gas for a vehicle. For example, a vessel such as Type 4 may be the target. The Type 4 pressure vessel (1) is specialized in maintaining high pressure and minimizing weight. Type 4 uses a liner (12) made of a high-molecular polymer material, and is configured together with a boss (11) for fastening a valve of the pressure vessel (1). At this time, there is a concern that the high-pressure gas may leak due to the gap between the boss (11) and the liner (12), so a sealing structure that can improve the airtightness of the pressure vessel (1) is important. In particular, when the gas is hydrogen, the size of the molecules is very small, so there is a high possibility of leakage, and in the event of a leak, a safety issue arises, so even greater airtightness is required. The pressure vessel (1) of the present invention has a sealing structure that improves airtightness by preventing gas leakage occurring at a gap between the boss (11) and the liner (12).

[0029] Each component of a pressure vessel (1) must be tightly sealed to prevent leakage of high-pressure gas. However, since the boss (11) and the liner (12) have different mechanical properties, a gap may develop with repeated charging and discharging, and there is a risk that gas may leak through the gap. Therefore, the present invention aims to prevent leakage of high-pressure gas by installing a sealing portion (13) having an energizer seal structure to improve airtightness.

[0030] The boss (11) is a port made of a material such as metallic steel or non-metallic aluminum, where a valve is connected to charge and discharge hydrogen, and is a component for fixing a rotation axis for filament winding the composite material layer (15). If the internal volume is small, the opposite side of the boss (11) is a closed structure, and if the internal volume is large, there is also a two-port structure that is open. Filament winding is a method of winding a composite material while applying tension to the surface of a mandrel (liner in the case of Type 4).

[0031] The boss (11) is provided in a cylindrical shape, and a through hole (110) is formed in the central portion in the vertical direction, and the lower portion is integrally expanded radially outward along the circumferential direction, and the through hole (110) is structured to extend in the vertical direction on the radially inner side. The through hole (110) can be formed in the vertical direction through the interior of the boss (11), and the upper end can be opened to the outside, and the lower end can be connected to the receiving space (120) inside the liner (12).

[0032] The liner (12) is provided in a container shape to form a receiving space (120) that is connected to the through hole (100) so that gas can be received inside, and the upper part can be hermetically bonded along the lower surface of the boss (11). The liner (12) can be provided with a high molecular polymer material that is different from the boss (11). The liner (12) can be manufactured using an injection molding method, a rotational method, a blowing method, etc. The liner (12) forms the shape of the pressure vessel (1) and can serve as a mandrel for filament winding.

[0033] The sealing portion (13) of the energizer seal structure prevents high-pressure gas from leaking between the joints when the boss (11) and the liner (12) are not completely bonded to each other. The joints are located at the boundary area between the boss (11) and the liner (12). The sealing portion (13) can be hermetically bonded to block gas leakage.

[0034] In general, the sealing part (13) uses an O-ring, gasket, etc. to maintain airtightness, but the present invention uses an energizer seal. In the case of a pressure vessel (1) that stores high-pressure gas, high-pressure gas of 700 bar is repeatedly charged and discharged at a temperature of -40 to +85 degrees, and is used for a long time, so strong durability is required. However, in the case of O-rings, gaskets, etc., there is a risk of tearing or damage over time due to repeated charging and discharging under low-temperature, high-temperature, and high-pressure conditions, and in the event of damage, there is a possibility of causing property damage or casualties due to gas leakage. Therefore, the present invention uses a highly durable energizer seal as the sealing structure instead of an O-ring, gasket, etc.

[0035] The locker (14) serves to prevent the sealing portion (13) from coming off due to contraction, expansion, and high pressure of the boss (11) or liner (12) in an environment of -40 to +85 degrees. The locker (14) may be in the shape of a nut.

[0036] The composite material layer (15) forms the exterior of the pressure vessel (1) and is composed of a carbon fiber composite material. Carbon fiber is lighter than metal materials and has very high tensile strength, enabling the pressure vessel (1) to withstand high pressures.

[0037] Figure 2 is a drawing illustrating a sealing part fastened according to one embodiment of the present invention.

[0038] Referring to Fig. 2, after the sealing part (13) is fastened to the sealing fastening part (15), the sealing part (13) is fastened with a locker (14). The sealing fastening part (15) is provided for sealing the joint between the boss (11) and the liner (12).

[0039] The boss (11) may include a screw thread (112) for fastening a valve (not shown) and a screw thread (114) for fixing a locker (14).

[0040] FIG. 3 is a drawing illustrating a gas leakage path according to one embodiment of the present invention.

[0041] Referring to FIG. 3, gas, for example, hydrogen, inside the pressure vessel (1) leaks along a leak path (30) formed at the boundary of the locker (14), sealing portion (13), boss (11), and liner (12).

[0042] To prevent gas leakage, a sealing member (13) is provided to block gas flowing in from the gas inflow path. The sealing member (13) is fastened to the joint between the boss (11) and the liner (12) and fastened with a locker (14).

[0043] In order to provide excellent confidentiality, the boss (11) and the liner (12) each have a protrusion protruding downward to which the locker (14) is fastened, and a sealing portion (13) is inserted between these protrusions.

[0044] FIG. 4 is a drawing illustrating a pressure vessel equipped with a sealing portion according to one embodiment of the present invention.

[0045] Referring to Fig. 4, when the locker (14) comes into contact with the sealing portion (13), there is a possibility that the sealing portion (13) may be damaged due to wear or other causes. Therefore, taking this into consideration, the locker (14) is fastened with a tolerance between the sealing portion (13) and the locking portion (14) so ​​as not to make direct contact, thereby preventing only the sealing portion (13) from coming off.

[0046] FIG. 5 is a drawing showing a detailed structure of a sealing portion according to one embodiment of the present invention.

[0047] Referring to FIG. 5, the sealing portion (13) of the energizer seal structure may include a main seal (131), a backup ring (132), a ring drop prevention portion (133), and a spring (134).

[0048] The main seal (131) forms the body of the sealing portion (13) and performs the main sealing function. A receiving portion (1310) for receiving a spring (134) is provided on one side of the main seal (131). The side of the receiving portion (1310) may have a curved shape corresponding to the outer shape of the spring (134). The main seal (131) may be composed of a high-performance plastic material (such as PTFE).

[0049] The backup ring (132) is positioned on at least one side of the main seal (131) and serves to maintain the position of the main seal (131). The backup ring (132) improves the performance of the sealing portion (13) and helps extend the life of the sealing portion (13), and one or two backup rings can be installed. Fig. 5 illustrates an example in which two rings are installed.

[0050] The functions of the backup ring (132) are as follows.

[0051] a) Pressure distribution: By effectively dispersing high pressure, the pressure applied to the sealing portion (13) is distributed, thereby preventing damage and deformation of the sealing portion (13).

[0052] b) Reduced wear of sealing part: The life of the sealing part (13) is extended by preventing wear when the sealing part (13) is repeatedly moved under high pressure. The backup ring (132) reduces wear by ensuring that the sealing part (13) is fixed in place.

[0053] D) Gap extrusion prevention: Prevents the sealing portion (13) from being extruded into the gap in a high-pressure environment. The backup ring (132) is located at the rear of the sealing portion (13) to prevent the sealing portion (13) from being pushed out into the gap.

[0054] The ring-drop prevention member (133) has a catch body to prevent the backup ring (132) from falling off. The catch body may be in the shape of a ring. The ring-drop prevention member (133) can prevent the backup ring (132) from falling off due to friction when the sealing member (13) is mounted. For example, the ring-drop prevention member (133) has an end with a rounded shape and an inclined edge.

[0055] The spring (134) ensures that the main seal (131) is tightly sealed, and can be opened as the pressure inside the pressure vessel (1) increases.

[0056] FIG. 6 is a drawing illustrating the structure of a sealing fastener according to one embodiment of the present invention.

[0057] (a) illustrates a sealing joint (15a) without a step between the boss (11) and the liner (12). When the liner (12) is injection-molded, a lifting phenomenon occurs at the joint between the boss (11) and the liner (12) due to shrinkage (90) of the high molecular polymer, which is the liner material. Accordingly, a lifting phenomenon also occurs when the sealing joint (13) is fastened, which reduces the sealing performance, and there is a concern that a gap extrusion phenomenon (a phenomenon in which the seal falls off) may occur as gas fills the lifting space, or the lifespan may be reduced due to wear.

[0058] (b) is a case where there is a step between the boss (11) and the liner (12), but there is a step between the injection mold (60) and the boss (11), and a sealing joint (15b) is shown. At the point of contact between the surfaces where the injection mold (60) and the boss (11) come into contact, there is a risk that a burr (80) may occur on the liner (12) during injection molding of the liner (12).

[0059] (c) is a case where a sealing fastening part (15c) is formed with a step shape (50) between the injection mold (60) and the boss (11) so that a burr (80) does not occur on the liner (12) during injection molding of the liner (12) and there is a step between the boss (11) and the liner (12) according to one embodiment of the present invention, and the problems occurring in (a) and (b) are solved.

[0060] Furthermore, the liner (12) may further include an undercut processing portion (70) to prevent a lifting phenomenon from occurring at the joint between the boss (11) and the liner (12) when shrinkage of the liner material occurs. The undercut area of ​​the undercut processing portion (70) refers to a portion that is dug out at the end of the liner (12) and remains recessed like a groove.

[0061] The present invention has been described above, focusing on specific embodiments thereof. Those skilled in the art will appreciate that variations and modifications can be made without departing from the essential characteristics of the invention. Therefore, the disclosed embodiments should be considered illustrative rather than limiting. The scope of the present invention is set forth in the claims, not the foregoing description, and all differences within the scope equivalent thereto should be construed as being encompassed by the present invention.

Claims

1. A boss having a cylindrical shape, a through hole formed in the central part in the up-and-down direction, and a boss that integrally extends radially outward along the circumference at the bottom; A liner having a shape of a pressure vessel and a receiving space connected to the through hole so that gas can be received inside, and an upper portion thereof is joined along the lower surface of the boss; and A sealing portion is included in the boundary area between the boss and the liner, which is hermetically bonded to block the outflow of gas contained in the receiving space; A pressure vessel characterized in that the above sealing portion is an energizer seal.

2. In the first paragraph, the sealing part A main seal forming a body and having a receiving portion on one side; A backup ring positioned on at least one side of the main seal to hold the position of the main seal; A ring drop prevention unit provided as a catch body to prevent the above backup ring from falling off; and A spring provided in the receiving portion of the main seal to ensure that the main seal is tightly sealed and that opens as the pressure inside the pressure vessel increases; A pressure vessel characterized by including:

3. In the first paragraph, the pressure vessel Includes a sealing fastener for fastening the sealing portion, The above sealing fastening portion has a step between the boss and the liner, A pressure vessel characterized by creating a stepped shape between an injection mold and a boss so as to prevent burrs from forming on the liner during liner injection molding.

4. In the first paragraph, the liner An undercut processing section to prevent lifting at the joint between the boss and the liner when shrinkage of the liner material occurs; A pressure vessel characterized by including:

5. In the first paragraph, the pressure vessel A locker that fastens the sealing portion with a gap between the sealing portion and the locking portion to prevent the sealing portion from coming off but not to make direct contact with the sealing portion; A pressure vessel characterized by further comprising:

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