JP7679795B2 - Pressure vessel liners - Google Patents

Description

The technology disclosed in this specification relates to a liner for a pressure vessel having a cylindrical body portion and a pair of dome portions provided at both axial ends of the body portion.

In the pressure vessel liner of Patent Document 1, the second liner located in the dome section is inserted inside the first liner located in the body section. In other words, in the pressure vessel liner, the second liner overlaps with the first liner in the radial direction of the body section.

JP 2020-112256 A

At low temperatures, the liner of the pressure vessel shrinks. The thickness of the second liner located in the dome section is greater than the thickness of the first liner located in the body section. Therefore, at low temperatures, the amount by which the second liner shrinks differs from the amount by which the first liner shrinks. As a result, in the liner of the pressure vessel of Patent Document 1, at low temperatures, the thicker second liner may deform the first liner radially inward. In this state, when high-pressure gas is filled inside the liner, there is a risk that the first and second liners will peel off from each other at the joint between them. This specification provides a technology for suppressing peeling of the liners at the joint between the first and second liners.

The pressure vessel liner disclosed in this specification is embodied in a pressure vessel having a cylindrical body portion and a pair of dome portions provided at both axial ends of the body portion. The pressure vessel liner comprises a first liner located in the body portion and a second liner located in the dome portion and having a thickness greater than that of the first liner. An end portion of the first liner is displaced inward toward the central axis of the body portion. An end face of the second liner is abutted and joined in the axial direction to the outer surface of the end portion of the first liner that is displaced inward.

In the pressure vessel described above, the end of the first liner is displaced inward toward the central axis of the body, and the second liner is joined to the outer surface of the end by abutting from the axial direction. This allows the end face of the second liner, which is thicker than the first liner, to be firmly fixed over a wide area to the outer surface of the end of the first liner, which is displaced inward toward the central axis. In addition, with this configuration, the first liner and the second liner do not overlap in the radial direction. Therefore, the effect of contraction of the first liner and the second liner, which have different thicknesses, at low temperatures can be suppressed. As a result, even if gas is filled at low temperatures, the first liner and the second liner are unlikely to peel off from each other. With the liner of the pressure vessel disclosed in this specification, peeling of the liners at the joint between the first liner and the second liner can be suppressed.

Details and further improvements of the technology disclosed in this specification are explained in the "Description of Embodiments" below.

1 shows a perspective view of a pressure vessel 2 including a liner 4 according to an embodiment of the present invention. An exploded view of the liner 4 is shown. 3 shows a cross-sectional view taken along line III-III in FIG. 2. A cross-sectional view of the process of forming the end 12 of the first liner 10 is shown. A cross-sectional view of a process of bonding the first liner 10 and the second liner 14e is shown. 6 shows a cross-sectional view of a step subsequent to the step in FIG. 5 .

(Example)
FIG. 1 shows a perspective view of a pressure vessel 2 including a liner 4 according to an embodiment. The pressure vessel 2 is mounted on, for example, a fuel cell vehicle (not shown). The pressure vessel 2 stores high-pressure hydrogen gas used for generating electricity in the fuel cell vehicle. The pressure vessel 2 has a cylindrical body portion 2c and a pair of dome portions 2d provided at both ends of the body portion 2c. Each of the pair of dome portions 2d is curved inwardly from the end of the body portion 2c in a spherical shape (i.e., a dome shape). In addition to the liner 4, the pressure vessel 2 includes a reinforcing layer 6, a mouthpiece 8v, and an end boss 8e. Hereinafter, the direction parallel to the central axis CL of the body portion 2c (i.e., the positive and negative directions of the X-axis in the coordinate system in the figure) is referred to as the axial direction.

The liner 4 is made of resin and forms a space for sealing hydrogen gas. The reinforcing layer 6 is a layer that reinforces the liner 4 by covering the outer surface of the liner 4. In this embodiment, the reinforcing layer 6 is wound around the outer surface of the liner 4 by a filament winding method. In a modified example, the reinforcing layer 6 may be wound around the outer surface of the liner 4 by another method.

The nozzle 8v is made of metal and is provided at one axial end of the liner 4 (i.e., the end on the right side in FIG. 1). The nozzle 8v has a through hole that connects the inside and outside of the liner 4. Hydrogen gas in the pressure vessel 2 is released to the outside through the through hole of the nozzle 8v, and hydrogen gas is supplied from the outside to the inside of the pressure vessel 2. The end boss 8e is made of metal and is provided at the other axial end of the liner 4 (i.e., the end on the left side in FIG. 1). Unlike the nozzle 8v, the end boss 8e does not have a through hole.

The detailed structure of the liner 4 will be described with reference to FIG. 2. FIG. 2 shows an exploded view of the liner 4. The liner 4 includes a first liner 10 and a pair of second liners 14v, 14e. The first liner 10 has a cylindrical shape and extends in the axial direction. The first liner 10 constitutes the body portion 2c of the pressure vessel 2 (see FIG. 1). The pair of second liners 14v, 14e are joined to the nozzle 8v and end boss 8e, respectively. The pair of second liners 14v, 14e are curved in a dome shape toward the nozzle 8v and end boss 8e, respectively. The pair of second liners 14v, 14e are joined to the end 12 of the first liner 10 in the axial direction. This completes the liner 4 that seals hydrogen gas inside.

A method for manufacturing the liner 4 will be described with reference to Figures 3 to 6. In this specification, a method for joining the first liner 10 and the second liner 14e will be described in particular. Figure 3 is a cross-sectional view taken along line III-III in Figure 2, and is an enlarged view showing the relationship between the end 12 of the first liner 10 and the end face 18 of the second liner 14e. Note that, although a method for joining the first liner 10 and one of the second liners 14e will be described below, the first liner 10 and the other second liner 14v are also joined in a similar manner.

3, the end 12 of the first liner 10 is curved toward the central axis CL. That is, the end 12 of the first liner 10 is displaced inward toward the central axis CL. As a result, the outer surface 16 of the end 12 faces the second liner 14e. The first liner 10 is composed of a first resin layer 10a and a second resin layer 10b. The first liner 10 is formed by simultaneously extruding three layers, the first resin layer 10a, the second resin layer 10b, and the first resin layer 10a, in that order, from a multi-layer die. The first liner 10 is formed by so-called multi-layer co-extrusion molding. The first liner 10, in which the three layers are stacked, has a first thickness T1. The first resin layer 10a and the second resin layer 10b are each composed of a different resin. By laminating multiple resin layers 10a, 10b, the first liner 10 can ensure relatively high rigidity even with a relatively small first thickness T1.

On the other hand, the second liner 14e is made of a single resin. The second liner 14e has a relatively complex shape that is curved in a dome shape. The second liner 14e is formed by injection molding. The second liner 14e has a second thickness T2. As shown in FIG. 3, the second thickness T2 is greater than the first thickness T1. The second liner 14e made of a single resin ensures high rigidity due to the second thickness T2 being greater than the first thickness T1. The second liner 14e is made of the same resin as the first resin layer 10a. The end surface 18 of the second liner 14e faces the outer surface 16 of the end 12 of the first liner 10.

Now, referring to FIG. 4, the process of forming the end 12 of the first liner 10 will be described. The end 12 of the first liner 10 formed by multi-layer co-extrusion molding is pressed against the mold 20. Furthermore, while the end 12 is pressed against the mold 20, the mold 20 is heated and then cooled. As a result, the end 12 of the first liner 10 is curved inward toward the central axis CL. Since the first liner 10 has a relatively simple cylindrical shape, the production efficiency of the first liner 10 can be improved by forming it by multi-layer co-extrusion molding. Furthermore, by curving the end 12 inward, the rigidity of the end 12 of the first liner 10 can be improved.

The process of joining the first liner 10 and the second liner 14e will be described with reference to Figures 5 and 6. As shown in Figure 5, the second liner 14e abuts against the outer surface 16 of the end 12 of the first liner 10 in the axial direction. As described above, the end 12 of the first liner 10 is displaced inward. Therefore, the length of the outer surface 16 of the end 12 of the first liner 10 is approximately the same as the thickness of the end face 18 of the second liner 14e (i.e., the second thickness T2).

As a result, the end surface 18 of the second liner 14e having the second thickness T2 abuts over a wide area against the outer surface 16 of the end 12 of the first liner 10. This allows the end surface 18 of the second liner 14e to be firmly bonded to the outer surface 16 of the end 12 of the first liner 10.

Then, as shown in FIG. 6, the joint between the first liner 10 and the second liner 14e is heated. As a result, the end face 18 of the second liner 14e and the end 12 of the first liner 10 both melt. Then, the liners 10, 14e are bonded to each other by cooling. As mentioned above, the first resin layer 10a forming the outer surface 16 of the first liner 10 and the second liner 14e are made of the same resin. Therefore, compared to a configuration in which different resins are bonded, it is relatively easy to bond the end face 18 of the second liner 14e to the outer surface 16 of the first liner 10.

As mentioned above, since both liners 10 and 14e are made of resin, when the ambient temperature of the pressure vessel 2 (see FIG. 1) changes, each of the liners 10 and 14e is significantly deformed. For example, at low temperatures, the liners 10 and 14e having different thicknesses each shrink by different amounts. As shown in FIG. 5 and FIG. 6, in the liner 4 of this embodiment, the end face 18 of the second liner 14e is joined to the outer surface 16 of the first liner 10 in the axial direction. Therefore, the first liner 10 and the second liner 14e do not overlap in the radial direction (i.e., the vertical direction of the paper surface in FIG. 6). Therefore, for example, even if the liners 10 and 14e having different thicknesses each shrink by different amounts at low temperatures, the joints of the liners 10 and 14e are unlikely to deform in the radial direction. Therefore, even if hydrogen gas is filled into the liner 4 at low temperatures, radial load is not likely to be applied to the joints of the liners 10 and 14e. As a result, radial separation of the liners 10 and 14e can be suppressed when hydrogen gas is filled at low temperatures.

Specific examples of the technology disclosed in this specification have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples given above. Modifications of the above examples are listed below.

(Variation 1) The first liner 10 does not have to have a three-layer structure. For example, the first liner 10 may have a single layer structure of the first resin layer 10a. Also, the end 12 of the first liner 10 does not have to be formed by the method of FIG. 4. For example, the first liner 10 may be formed by injection molding.

(Variation 2) The radial length of the outer surface 16 of the end 12 of the first liner 10 does not have to be approximately equal to the second thickness T2. The radial length of the outer surface 16 may be longer or shorter than the second thickness T2.

The technical elements described in this specification or drawings have technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of those objectives is itself technically useful.

2: Pressure vessel 2c: Body portion 2d: Dome portion 4: Liner 6: Reinforcing layer 8e: End boss 8v: Cap 10: First liner 10a: First resin layer 10b: Second resin layer 12: Ends 14e, 14v: Second liner 16: Outer surface 18: End surface 20: Mold CL: Central axis T1: First thickness T2: Second thickness

Claims (1)

A liner for a pressure vessel, comprising:
The pressure vessel includes a cylindrical body portion and a pair of dome portions provided at both ends of the body portion in an axial direction,
The liner comprises:
It is made of resin and reinforced with a reinforcing layer on the outside.
a first liner located in the fuselage;
a second liner located in the dome portion and having a thickness greater than that of the first liner;
an end of the first liner is displaced inwardly toward a central axis of the fuselage;
A liner for a pressure vessel, wherein an end face of the second liner is abutted and joined in the axial direction to an outer surface of the end portion of the first liner that displaces inward.

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