KR102322371B1 - Pressure vessel including reinforced cylinder part - Google Patents

Abstract

The present invention provides a structure of a pressure vessel capable of improving the strength of the pressure vessel itself and reducing the weight of the vessel by selectively applying a reinforcing structure to a portion vulnerable to rupture due to internal pressure in the pressure vessel.
To this end, in a preferred embodiment of the present invention, as a pressure vessel having a dome portion and a cylinder portion, a stepped structure having regions having different thicknesses is adopted in the cylinder portion, and a fiber composite reinforcing layer is laminated in the step structure, characterized in that It is characterized in providing a pressure vessel with a reinforced cylinder portion.

Description

Pressure vessel including reinforced cylinder part

The present invention relates to a pressure vessel, and more particularly, to a pressure vessel for storing high-pressure gas.

In order to store various types of gases such as hydrogen, nitrogen, and natural gas, and to discharge the stored gas as necessary, a gas storage container is required. In particular, the gas needs to be stored at high pressure because the storage density in the vessel is low, and the pressure vessel is essential for use in such a high pressure environment.

For example, in an alternative fuel gas vehicle (fuel cell vehicle or compressed natural gas vehicle), the structure of the storage system changes depending on the storage method of fuel gas. storage method is gaining popularity. However, since gaseous fuel has a low energy storage density, it is necessary to increase the storage amount or increase the storage pressure to secure a longer driving distance. In the case of automobiles, there is a limit to increasing the size of the storage tank due to the limited space for mounting the gas storage system.

In the case of a composite tank among fuel gas storage tanks, the outer shell is reinforced with a fiber-reinforced composite material with high specific strength and specific stiffness to handle the internal pressure caused by compressed gas, and a liner that maintains gas tightness is inserted inside. do. Fuel gas storage tanks are divided into types depending on the material of the liner. A tank with a metal liner such as aluminum is classified as Type 3, and a tank with a high-density polymer liner is divided into Type 4 (Type 4). . In the case of Type 3, the stability is relatively high, but it is expensive and has poor fatigue resistance, whereas the Type 4 tank is cheaper than Type 3 and has excellent fatigue resistance, but hydrogen leakage and permeation resistance. There are safety issues such as poor performance.

In general, the pressure vessel is manufactured in such a way that the carbon fiber composite material is laminated while being wound in order to withstand the internal pressure. In this case, the strength of the material varies depending on the laminate thickness and angle due to the characteristics of the composite material having anisotropy.

On the other hand, the hydrogen tank is made of expensive carbon fiber, and in order to improve the hydrogen weight efficiency of the container and the fuel efficiency of the vehicle, an optimal lamination pattern capable of reducing the weight while improving the strength of the pressure container itself is required. In particular, it is necessary to design a container capable of manufacturing a high-strength pressure container while reducing the amount of expensive carbon fiber used.

US Patent Publication No. 2002-0088806 (2002. 07. 11) Japanese Patent Laid-Open No. 2011-102614 (2011.05.26)

The present invention has been devised to solve the above problems. In the present invention, by selecting a portion vulnerable to rupture due to internal pressure in the pressure vessel, and selectively applying a reinforcing structure to the selected portion, the rupture of the pressure vessel itself An emphasis is placed on providing a structure of a pressure vessel capable of reducing the amount of material consumed in manufacturing the vessel while increasing the strength as well as reducing the weight of the vessel.

In order to achieve the above object, in a preferred embodiment of the present invention, dome portions at both ends of the pressure vessel; and a liner comprising: a cylinder portion connected to the dome portions; wherein the cylinder portion comprises first and second areas adjacent to the dome portions, respectively, and a third area between the first and second areas. The cylinder part, characterized in that the liner thickness of the third region is formed thinner than the thickness of the liner of the first region and the second region, and a fiber composite reinforcing layer is laminated on the outside of the liner in the third region A reinforced pressure vessel is provided.

In addition, a space is formed on the outer surface of the third region due to a thickness difference, and the fiber composite reinforcing layer is laminated in the space.

In addition, the third region provides a pressure vessel with a reinforced cylinder portion, characterized in that formed to have a stepped structure at the boundary between the first region and the second region.

In addition, the third region provides a cylinder-reinforced pressure vessel, characterized in that it has a rounded curved structure at the boundary between the first region and the second region.

In addition, there is provided a pressure vessel reinforced with a cylinder part, characterized in that the liner and the fiber composite layer is further laminated on the outside of the fiber composite reinforcement layer.

In addition, there is provided a pressure vessel with a reinforced cylinder portion, characterized in that the thickness of the liner in the second region is 20% or more and less than 50% of the thickness of the liner in the first region or the third region.

In addition, the fiber composite reinforcing layer of the second region provides a pressure vessel reinforced with a cylinder part, characterized in that the fiber composite is laminated while being wound.

According to a preferred embodiment of the present invention, by adopting the reinforcing structure of the cylinder portion of the pressure vessel, the strength (bursting pressure) of the cylinder portion of the pressure vessel, which is a weak portion, can be increased, thereby improving the strength of the pressure vessel itself. have

In addition, according to a preferred embodiment of the present invention, since the burst strength of the pressure vessel itself is increased, it is possible to reduce the use of an expensive composite material, thereby reducing the weight of the vessel itself.

In addition, when the pressure vessel according to a preferred embodiment of the present invention is mounted on a vehicle for the purpose of storing hydrogen, the fuel efficiency of the vehicle itself can be improved due to a reduction in the weight of the vessel, and vehicle stability can be improved due to an increase in burst strength. can have an effect.

1 is a cross-sectional view of a pressure vessel for explaining the structure of the pressure vessel,
Figure 2 illustrates the winding angle in the dome portion and the cylinder portion,
3 is a cross-sectional view of an inner liner used in a pressure vessel reinforced with a cylinder portion according to a preferred embodiment of the present invention;
4 is a cross-sectional view of a pressure vessel in which a cylinder part is reinforced according to a preferred embodiment of the present invention;
Figure 5 shows a stress display section in a part of the pressure vessel of Figure 4,
Figure 6a shows the hoop layer stress and stress reduction in the stress display section of Figure 5,
6B shows the hoop layer stress and the stress reduction rate within the stress display section of FIG. 5 .

The present invention relates to a pressure container for storing high-pressure gas, a container that secures airtightness so that the high-pressure gas stored in the container does not leak, and a new structure capable of improving the strength of burst pressure due to the high-pressure gas stored inside the container of the pressure vessel.

In particular, the present invention relates to a pressure vessel for storing fuel gas of a vehicle, which can be a pressure vessel in which a composite material is used, for example type 4 .

In the case of the Type 4 liner currently in use, the coupling between the metal boss and the plastic body is largely divided into an integral injection type and an assembly type structure, and is manufactured in a structure that can maintain airtightness between the metal boss and the plastic body.

However, it should be noted that the pressure vessel described as a preferred embodiment of the present invention is not limited to the type of such vessel, and can be applied without limitation as long as the composite material is a structure reinforced on the outside of the liner.

In particular, in the present specification, the fiber composite material is described as a structure in which the fiber composite material supplied from the fiber supply unit is wound outside the liner, but the invention described in the claims is not limited to this example, and the composite material is outside the liner through another method. should be construed as including a stacked structure.

In addition, the liner positioned inside the composite material is described herein as a plastic liner coupled to the metal boss, but is not limited to this example, and may be configured as a single liner structure in which the boss part and the liner are integrated. , may be combined with a boss of a different material, or may be made of a liner having a different coupling structure. In addition, although the preferred embodiment of the present invention is described as a pressure vessel including a plastic liner as in Type 4, the material of the liner may also be changed without changing the gist of the present invention.

Accordingly, the present invention is not limited to the drawings and examples presented as preferred embodiments, but should be construed to cover various modifications such as those mentioned above.

Hereinafter, with reference to the accompanying drawings, a pressure vessel reinforced with a cylinder portion according to a preferred embodiment of the present invention will be described in detail.

1 is a cross-sectional view of a pressure vessel for explaining the basic structure of the pressure vessel. As shown in FIG. 1, the type 4 pressure vessel has a structure in which a container body in which a metal boss and a plastic liner are combined is formed on the inside, and a fiber composite layer 30 is laminated on the outside thereof.

The pressure vessel has a symmetrical structure with respect to a central axis, and has a structure in which a dome-shaped structure and a cylinder-shaped structure are integrally formed. Specifically, as shown in FIG. 1 , the pressure vessel includes a dome portion forming a dome shape from the boss portion 10 on the central axis, a cylinder portion located in the middle region of the pressure vessel, and a conversion portion located between the dome portion and the cylinder portion.

In particular, in the case of the dome part and the cylinder part, when the fiber composite material is laminated while being wound, the windings are made at different angles.

Specifically, FIG. 2 exemplifies the winding angle between the dome part and the cylinder part, and while the dome part is wound at a small angle with respect to the central axis, a helical layer is formed. On the other hand, in the cylinder part, the hoop layer is formed while being wound at an angle substantially perpendicular to the central axis.

Accordingly, the helical layer of the fiber composite material is stacked in the dome portion, and the helical layer should be thickly stacked in order to reinforce the vicinity of the metal boss portion 10 . In addition, in the case of the cylinder part, the composite helical layer and the hoop layer are stacked together to form a straight section of the pressure vessel.

On the other hand, in the case of the conversion part, it is a section where the composite hoop layer ends, a section in which the straight section of the pressure vessel changes to a curved section, and preferably a section in which the winding angle of the helical layer starts to change.

In a preferred embodiment of the present invention, the cylinder part of the pressure vessel is a part vulnerable to rupture, the weak part is selected by performing stress analysis on the part, and a reinforcing structure for reinforcing the selected weak part in the cylinder part is presented.

In this regard, FIG. 5 shows the stress display section in the cylinder part of the pressure vessel, and FIGS. 6A and 6B show the stress analysis results in the stress display section.

Specifically, as shown in FIG. 4 , the stress display section is based on the center of the cylinder part of the pressure vessel, and the central part is set as the stress display starting point. was interpreted.

First, FIG. 6A shows the hoop layer stress and the stress reduction within the stress display section, and the stress gradually decreases as it moves from the center of the cylinder part, that is, the stress display starting point to the dome part, as shown in FIG. 6A . Similarly, the stress drop is sharply reduced near the point passing 50% of the distance from the center of the cylinder part to the dome part.

On the other hand, Figure 5b shows the acceleration rate at which the stress reduction in Figure 5a is made, that is, as can be seen in the graph of Figure 5b, the stress reduction rate within the stress display section is about 50% of the linear portion of the cylinder. decreases rapidly over time.

According to this analysis result, the following items can be confirmed.

First, in the case of a pressure vessel including a dome portion and a cylinder portion, the stress of the hoop layer of the cylinder portion is not constant over the entire length, and decreases as it approaches the dome portion.

In addition, in the cylinder part, after a certain section (about 50% of the straight part of the cylinder) passes, the hoop layer stress is rapidly reduced. In particular, when the pressure vessel is pressurized, the load is concentrated in about 50% of the straight section with respect to the center of the cylinder.

In consideration of this point, the present invention proposes a structure in which a stepped space is formed in the central region of the cylinder, that is, an outer part of the plastic liner 20 is deleted, while a fiber composite material is inserted and laminated in the space. It is characterized in providing a structure capable of reinforcing the area of the cylinder portion where the load is concentrated by making the structure.

Specifically, FIG. 3 shows a cross-section of an inner liner used in a pressure vessel having a cylinder portion reinforced according to a preferred embodiment of the present invention.

As shown in FIG. 3 , a partial thickness of the liner is removed from the center of the hydrogen tank inner liner 20 , and the fiber composite layer 30 is formed in the deleted area.

That is, as shown in FIG. 3 , according to a preferred embodiment of the present invention, the cylinder portion of the liner 20 is divided into three regions based on the central portion, and the first region and the second region on both sides of the dome portion are on the central side. It is configured to have a relatively thick thickness compared to the third region. Preferably, as shown in FIG. 3 , the third region is formed to have a step difference at the boundary between the first region and the second region, and accordingly, the outer surface of the third region of the liner 20 is formed between the first region and the second region. It is located inward compared to the outer surface of the second region, and has a space for additionally stacking the fiber composite material on the outer surface of the third region.

A fiber composite material is laminated in the space of the third region, and preferably, the fiber composite material may be laminated while forming a hoop layer by a winding method while forming the fiber composite material reinforcing layer 21 . However, the method of forming the fiber composite reinforcing layer 21 is not limited to this winding method, and other methods capable of forming the fiber composite layer 30 while filling the corresponding space may be applied.

Therefore, a step is formed in the center of the liner cylinder part to create a space, and by adopting a structure in which the fiber composite reinforcing layer 21 is laminated in the space, the weak part of the cylinder part can be reinforced, so that the strength of the pressure vessel is improved. effect can be obtained.

The second region of the liner 20 may have a stepped structure in a direction perpendicular to the surface of the cylinder, as shown in FIG. 3 . However, the boundary portion structure of the second region may have a rounded curved surface structure to prevent stress concentration in the step portion.

In addition, in the second region, the thickness of the fiber composite reinforcing layer 21 may be 50% or more of the total thickness of the liner 20, preferably considering the risk of damage to the liner 20, the fiber composite reinforcing layer ( The thickness of 21) may be composed of less than 80%. That is, the thickness of the liner in the third region is preferably 20% or more to less than 50% of the thickness of the liner in the second region. In this case, it is possible to properly prevent gas leakage by the liner, and it is possible to maximize the reinforcing effect of the fiber composite reinforcing layer 21 .

4 is an overall cross-sectional view of the pressure vessel in which the fiber composite material layer 30 is again stacked on the outside of the liner 20 having a structure in which the center is reinforced as in FIG. 3 .

That is, as shown in FIG. 4, the fiber composite material layer 30 is additionally laminated on the outside of the fiber composite reinforcing layer 21 on the outside of the liner 20, on the entire cylinder part, the conversion part, and the dome part, such a fiber composite layer ( 30) is the same as the conventional type 4 fiber composite layer. Accordingly, the additionally laminated fiber composite layer may be wound outside the container while forming the helical layer and the hoop layer by the winding method as in the conventional method.

Therefore, according to the embodiment of the present invention, it is possible to improve the rupture strength of the weak part by providing a structure in which a fiber composite reinforcing layer and a liner layer are laminated inside the fiber composite layer 30 on the outside of the central side of the cylinder part, through which , since sufficient strength can be obtained even when the thickness of the composite material is laminated relatively thinly in the remaining part except for the weak part, it is possible to reduce the use of expensive composite material, thereby reducing the weight of the entire container.

As described above, the present invention has been described with reference to preferred embodiments, but those skilled in the art will understand that modifications and changes to the elements of the present invention are possible without departing from the scope of the present invention. In addition, many changes may be made to materials or specific circumstances without departing from the essential scope of the present invention. Therefore, the present invention is not limited to the detailed description of the preferred embodiments of the present invention, but it is intended to cover all embodiments within the scope of the appended claims.

10: boss
20: liner
21: fiber composite reinforcement layer
30: fiber composite layer

Claims (7)

dome portions at both ends of the pressure vessel;
It includes a liner consisting of; a cylinder part formed by being connected to the dome parts,
The cylinder part comprises a first region and a second region adjacent to the dome parts, respectively, and a third region between the first region and the second region,
The thickness of the liner in the third region is thinner than the thickness of the liner in the first region and the second region, and a fiber composite reinforcing layer is laminated outside the liner in the third region,
A space is formed on the outer surface of the third region by a thickness difference, and the fiber composite reinforcing layer is laminated in the space,
The third region is formed to have a stepped structure at the boundary between the first region and the second region, and has a rounded curved structure at the boundary between the first region and the second region. Additional reinforced pressure vessel.
delete delete delete The method according to claim 1,
A pressure vessel reinforced with a cylinder part, characterized in that the liner and the fiber composite material layer are further laminated on the outside of the fiber composite material reinforcement layer.
The method according to claim 1,
The pressure vessel with a reinforced cylinder portion, characterized in that the thickness of the liner in the third region is 20% or more and less than 50% of the thickness of the liner in the first region or the second region.
The method according to claim 1,
The pressure vessel reinforced with a cylinder part, characterized in that the fiber composite reinforcing layer in the second region is laminated while the fiber composite is wound.

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