Pressure vessel

A pressure vessel includes a vessel body, a covering part, and a cylindrical mouthpiece. The vessel body includes a cylindrical open end portion on at least one end side of the vessel body. The covering part is made of a fiber reinforced resin and covers an outer surface of the vessel body. The mouthpiece is configured such that a plurality of mouthpiece bodies each having a projection on an inner surface of the mouthpiece body is connected to each other in a circumferential direction of the open end portion. The mouthpiece is attached to an outer peripheral surface of the open end portion by the projections biting into the covering part covering the outer peripheral surface of the open end portion. The mouthpiece bodies of the mouthpiece are connected to each other by fitting together fitting portions formed at end portions of the mouthpiece bodies in the circumferential direction.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2019-202659 filed on Nov. 7, 2019 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The disclosure relates to a pressure vessel.

2. Description of Related Art

Hitherto, there is known a pressure vessel that includes a cylindrical liner and a reinforcing part (reinforcing layer) made of a carbon fiber reinforced resin (CFRP) and configured to reinforce the liner, and stores hydrogen inside (see, e.g. Japanese Unexamined Patent Application Publication No. 2018-112204 (JP 2018-112204 A)). A mouthpiece is firmly attached to an open end portion of the liner of the pressure vessel. Specifically, projections of the mouthpiece bite into the reinforcing part (reinforcing layer).

SUMMARY

As the structure of the mouthpiece, it is conceivable that a plurality of (e.g. eight) mouthpiece bodies are connected to each other by thin plate-like connecting parts each having its thickness direction along the radial direction and that the mouthpiece is attached to the open end portion of the liner as the vessel body by locally deforming the connecting parts (seeFIG. 12). With this structure, there is an advantage that it is possible to reduce the number of components forming the mouthpiece.

However, with such a structure, there is a possibility that when attaching the mouthpiece to the open end portion of the liner by locally deforming the connecting parts, the mouthpiece bodies cannot be equally pressed radially inward due to variation of forces applied for such deformation or the like, resulting in the occurrence of a crack or the like in one or some of the connecting parts.

It is therefore an object of the disclosure to provide a pressure vessel that can prevent the occurrence of a crack or the like in a mouthpiece when attaching the mouthpiece to an open end portion of a vessel body.

A first aspect of the disclosure relates to a pressure vessel including a vessel body, a covering part, and a cylindrical mouthpiece. The vessel body includes a cylindrical open end portion on at least one end side of the vessel body and is configured to be filled with a gas. The covering part is made of a fiber reinforced resin and covers an outer surface of the vessel body. The mouthpiece is configured such that a plurality of mouthpiece bodies each having a projection on an inner surface of the mouthpiece body is connected to each other in a circumferential direction of the open end portion. The mouthpiece is attached to an outer peripheral surface of the open end portion by the projections biting into the covering part covering the outer peripheral surface of the open end portion. The mouthpiece bodies of the mouthpiece are connected to each other by fitting together fitting portions formed at end portions of the mouthpiece bodies in the circumferential direction.

According to the first aspect, the cylindrical mouthpiece attached to the outer peripheral surface of the open end portion of the vessel body by the projections biting into the covering part covering the outer peripheral surface of the open end portion is configured by connecting the mouthpiece bodies in the circumferential direction of the open end portion. The mouthpiece bodies of the mouthpiece are connected to each other by fitting together the fitting portions formed at the end portions of the mouthpiece bodies in the circumferential direction. Therefore, when attaching the mouthpiece to the vessel body, the portions connecting the mouthpiece bodies to each other are not locally deformed. Consequently, a crack or the like is prevented from occurring in the portions connecting the mouthpiece bodies to each other in the mouthpiece.

According to a second aspect of the disclosure, in the pressure vessel according to the first aspect, the fitting portion may include a recessed portion formed at a first end portion of each of the mouthpiece bodies in the circumferential direction, and a protruding portion formed at a second end portion of each of the mouthpiece bodies in the circumferential direction, and the mouthpiece bodies of the mouthpiece may be connected to each other by fitting the protruding portion of one of the adjacent mouthpiece bodies to the recessed portion of the other of the adjacent mouthpiece bodies.

According to the second aspect, the fitting portion includes the recessed portion formed at the first end portion of each of the mouthpiece bodies in the circumferential direction, and the protruding portion formed at the second end portion of each of the mouthpiece bodies in the circumferential direction, and the mouthpiece bodies of the mouthpiece are connected to each other by fitting the protruding portion of one of the adjacent mouthpiece bodies to the recessed portion of the other of the adjacent mouthpiece bodies. Therefore, the mouthpiece bodies are easily connected to each other.

According to a third aspect of the disclosure, in the pressure vessel according to the second aspect, the protruding portion may be configured to be press-fitted into the recessed portion.

According to the third aspect, the protruding portion is press-fitted into the recessed portion. Therefore, compared to a configuration having a gap between the protruding portion and the recessed portion, the sealability in the fitting portion is improved.

According to a fourth aspect of the disclosure, in the pressure vessel according to the second aspect, a bulging portion bulging at least in a radial direction of the open end portion may be formed at an end portion of the protruding portion on a downstream side in a fitting direction of the protruding portion to the recessed portion, and the bulging portion may be configured to be press-fitted into the recessed portion.

According to the fourth aspect, the bulging portion bulging at least in the radial direction of the open end portion is formed at the end portion of the protruding portion on the downstream side in the fitting direction of the protruding portion to the recessed portion and is press-fitted into the recessed portion. Therefore, compared to a configuration having a gap between the bulging portion and the recessed portion, the sealability in the fitting portion is improved.

As described above, according to the disclosure, it is possible to prevent the occurrence of a crack or the like in the mouthpiece when attaching the mouthpiece to the open end portion of the vessel body of the pressure vessel.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the disclosure will be described in detail below with reference to the drawings. For convenience of description, arrow S, arrow R, and arrow C that are shown in the respective figures as appropriate respectively indicate the axial direction of a pressure vessel10, the radial direction of the pressure vessel10, and the circumferential direction of the pressure vessel10. Therefore, when the axial direction, the radial direction, and the circumferential direction are used in the following description, these directions respectively indicate the axial direction, the radial direction, and the circumferential direction of the pressure vessel10(including later-described open end portions14), unless specifically stated otherwise.

As illustrated inFIG. 1, the pressure vessel10according to this embodiment forms a part of a tank module (illustration omitted) mounted in a fuel cell vehicle (illustration omitted). The tank module includes a plurality of pressure vessels10connected to each other via later-described fastening parts18or the like.

The pressure vessel10includes a liner12as a vessel body to be filled with gaseous hydrogen, a reinforcing layer16as a covering part that covers the outer surface of the liner12from the outside to reinforce the liner12, and cylindrical mouthpieces20each attached, via the reinforcing layer16, to the outer peripheral surface of the cylindrical open end portion14formed at each of both ends of the liner12.

The liner12is made of a resin material such as a polyamide synthetic resin and has a generally cylindrical shape. More specifically, the liner12has a cylindrical body portion12A having a constant inner diameter and a constant outer diameter and located at an intermediate portion of the liner12in its longitudinal direction (axial direction), and shoulder portions12B forming both side portions of the liner12in its longitudinal direction (axial direction) and each gradually narrowing toward the side away from (axially outward of) the body portion12A.

The liner12has the cylindrical open end portions14forming both end portions of the liner12in its longitudinal direction (axial direction) (portions axially outward of the shoulder portions12B) and having an inner diameter and an outer diameter that are smaller than those of the body portion12A and the shoulder portions12B and are approximately constant.

The reinforcing layer16is formed such that tapes (illustration omitted) made of a fiber reinforced resin are wound around the entire outer surface of the liner12in a plurality of layers. The thickness of the reinforcing layer16increases toward the open end portion14sides from the body portion12A side of the liner12. Further, in the reinforcing layer16, the outer diameter (the outer diameter before the mouthpiece20is attached) of a portion corresponding to each of the open end portions14of the liner12is approximately constant. In this embodiment, a carbon fiber reinforced resin (CFRP) is used as one example of the fiber reinforced resin (FRP).

The mouthpieces20are respectively attached to the open end portions14of the liner12covered with the reinforcing layer16, i.e. attached to the reinforcing layer16on the open end portions14of the liner12. Further, the fastening parts18are respectively attached to the mouthpieces20. With this configuration, the open end portion14of the liner12on its one side is closed by one of the fastening parts18, and the open end portion14(illustration omitted) of the liner12on its other side is connected to another pressure vessel10via the other one of the fastening parts18(illustration omitted). InFIG. 1, the open end portion14of the liner12on the side closed by the fastening part18is illustrated.

First Embodiment

Next, the configuration of the mouthpiece20according to a first embodiment will be described.

As illustrated inFIGS. 2, 4, and 7, the mouthpiece20is formed to a cylindrical shape using a metal material. Specifically, the mouthpiece20is formed by a plurality of (in this embodiment, eight) mouthpiece bodies22disposed in the circumferential direction. Each of the mouthpiece bodies22extends in the axial direction with its thickness direction along the radial direction and is formed to a plate shape that is curved radially outward as viewed from the axial direction.

An axially outward end face of each mouthpiece body22is a flat surface23that is disposed flush with an end face of the open end portion14(the reinforcing layer16), and an axially inward end face of each mouthpiece body22is integrally formed with a flange portion24that is bent radially outward. The flange portion24is formed to a generally isosceles triangular shape with an obtuse vertical angle as viewed from the axial direction.

As illustrated inFIGS. 1, 3, 5, and 7, the inner peripheral surface (inner surface) of each mouthpiece body22is formed with a plurality of locking pawls26as projections so that the inner peripheral surface of each mouthpiece body22has a knurled surface with the locking pawls26. In sectional views taken along the axial direction and the radial direction, the locking pawls26are formed to a saw blade shape such that the locking pawls26are pointed on the tip side in the projecting direction (on the radially inner side).

More specifically, as illustrated inFIG. 6, in each of the locking pawls26, a surface facing the body portion12A side of the liner12is an inclined surface26A that is inclined axially outward as going radially inward. Further, in each locking pawl26, a surface on the side opposite to the surface facing the body portion12A side of the liner12is a perpendicular surface26B extending along the radial direction.

Further, a portion at which the inclined surface26A and the perpendicular surface26B cross each other is a tip portion26C of the locking pawl26. It is configured that the tip portions26C of the locking pawls26bite into the outer peripheral portion of the reinforcing layer16covering the outer peripheral surface of the open end portion14so that the mouthpiece20is firmly (non-rotatably) attached to the open end portion14.

As illustrated inFIGS. 1, 3, 5, and 7, screw grooves28are formed on the outer peripheral surface (outer surface) of each mouthpiece body22(the screw grooves28are omitted inFIGS. 2 and 4). It is configured that when the mouthpiece20is attached to the open end portion14(when the mouthpiece bodies22are connected to each other), a helical male screw portion29along the circumferential direction and the axial direction is formed by the screw grooves28. A later-described female screw portion19of the fastening part18is screwed into the male screw portion29.

As illustrated inFIGS. 7 to 9, fitting portions30for connecting the mouthpiece bodies22to each other in the circumferential direction are respectively formed at end portions of the mouthpiece bodies22in the circumferential direction. The fitting portion30includes a recessed portion32formed at a first end portion of each mouthpiece body22in the circumferential direction, and a protruding portion34formed at a second end portion of each mouthpiece body22in the circumferential direction.

More specifically, the recessed portion32is formed at a substantially radially middle portion of each mouthpiece body22at the first end portion, and is cut out into an elongated generally rectangular shape with its longitudinal direction along the circumferential direction as viewed from the axial direction. The length of the recessed portion32in the axial direction is the same as the length of the mouthpiece body22excluding the flange portion24in the axial direction.

The protruding portion34is formed at a substantially radially middle portion of each mouthpiece body22at the second end portion, and protrudes into an elongated generally rectangular shape with its longitudinal direction along the circumferential direction as viewed from the axial direction. The length of the protruding portion34in the axial direction is the same as the length of the mouthpiece body22excluding the flange portion24in the axial direction. A leading end surface34A of the protruding portion34is an arc surface formed to an arc shape.

The mouthpiece bodies22are connected to each other in the circumferential direction by fitting the protruding portion34of one of the adjacent mouthpiece bodies22into the recessed portion32of the other of the adjacent mouthpiece bodies22so that the cylindrical mouthpiece20is formed. The depth (length) of the recessed portion32in the circumferential direction is set to be a little deeper (longer) than the protruding length of the protruding portion34in the circumferential direction. In other words, when the protruding portion34is fitted into the recessed portion32, a gap is formed between a bottom surface32A of the recessed portion32and the leading end surface34A of the protruding portion34(seeFIG. 9).

Therefore, it is configured that when the protruding portion34is fitted into the recessed portion32, an end face22A of one of the adjacent mouthpiece bodies22in the circumferential direction and an end face22B of the other of the adjacent mouthpiece bodies22in the circumferential direction come in contact with each other. In other words, it is configured that a gap is not formed between the end face22A of one of the adjacent mouthpiece bodies22in the circumferential direction and the end face22B of the other of the adjacent mouthpiece bodies22in the circumferential direction.

Further, the width of the recessed portion32in the radial direction is set to be slightly smaller than the width of the protruding portion34in the radial direction (the width of the protruding portion34in the radial direction is set to be slightly greater than the width of the recessed portion32in the radial direction). Therefore, when the protruding portion34is fitted into the recessed portion32, the protruding portion34is press-fitted into the recessed portion32. Consequently, it is configured that even when a resin is impregnated into the reinforcing layer16by resin transfer molding (RTM), sealing is performed to prevent leakage of the resin from the radially inner side to the radially outer side of the mouthpiece20.

Next, the operation of the pressure vessel10including the mouthpiece20according to the first embodiment configured as described above will be described.

First, the process of attaching the mouthpiece20according to the first embodiment to the open end portion14of the liner12will be described. The eight mouthpiece bodies22are provisionally connected to each other by provisionally press-fitting the protruding portions34into the recessed portions32, thereby forming the generally cylindrical mouthpiece20. Then, as illustrated inFIGS. 2 and 3, the generally cylindrical mouthpiece20is disposed to be fitted on the outer peripheral side of the open end portion14of the liner12(the outer peripheral side of the reinforcing layer16) (mouthpiece disposing process). Consequently, the tip portions26C of the locking pawls26of the mouthpiece bodies22of the mouthpiece20are disposed in close proximity to the outer peripheral surface of the reinforcing layer16(with gaps therebetween).

Then, as illustrated inFIGS. 4 and 5, the fitting portions30of the mouthpiece20are fitted together to reduce the diameter of the mouthpiece20(mouthpiece fitting process). That is, the protruding portions34provisionally press-fitted into the recessed portions32are press-fitted more deeply. Consequently, the mouthpiece bodies22are moved radially inward (reduced in diameter) so that the end face22A of one of the adjacent mouthpiece bodies22and the end face22B of the other of the adjacent mouthpiece bodies22come in contact with each other, resulting in that the locking pawls26bite into the reinforcing layer16. In this way, the mouthpiece20is attached to the open end portion14of the liner12via the reinforcing layer16.

Herein, a comparative example illustrated inFIG. 12will be described. A mouthpiece40according to the comparative example has a structure that eight mouthpiece bodies42are connected to each other by thin plate-like connecting parts44each having its thickness direction along the radial direction and that the mouthpiece40is attached to the open end portion14of the liner12by locally deforming the connecting parts44. With this structure, there is a possibility that the mouthpiece bodies42cannot be equally pressed radially inward due to variation of forces applied for such deformation or the like, resulting in the occurrence of a crack K or the like in one or some of the connecting parts44.

On the other hand, the mouthpiece20according to this embodiment is configured by connecting the eight mouthpiece bodies22in the circumferential direction by the fitting portions30. That is, in the mouthpiece20, the mouthpiece bodies22are connected to each other by fitting together the fitting portions30formed at the end portions of the mouthpiece bodies22in the circumferential direction. Therefore, when attaching the mouthpiece20to the open end portion14of the liner12, the portions connecting the mouthpiece bodies22to each other are not locally deformed. Consequently, it is possible to prevent the occurrence of a crack or the like in the portions connecting the mouthpiece bodies22to each other in the mouthpiece20.

Further, the fitting portion30is formed by the recessed portion32formed at the first end portion of each mouthpiece body22in the circumferential direction, and the protruding portion34formed at the second end portion of each mouthpiece body22in the circumferential direction, and the mouthpiece bodies22of the mouthpiece20are connected to each other by fitting the protruding portion34of one of the adjacent mouthpiece bodies22into the recessed portion32of the other of the adjacent mouthpiece bodies22. Therefore, the mouthpiece bodies22can be easily connected to each other.

Further, the protruding portion34is press-fitted into the recessed portion32. Therefore, a gap in the radial direction is not formed between the recessed portion32and the protruding portion34. Further, a gap is formed between the bottom surface32A of the recessed portion32and the leading end surface34A of the protruding portion34. Therefore, the end face22A of one of the adjacent mouthpiece bodies22in the circumferential direction and the end face22B of the other of the adjacent mouthpiece bodies22in the circumferential direction firmly contact with each other so that a gap is not formed also between the end face22A and the end face22B.

In other words, if the leading end surface34A of the protruding portion34abuts against the bottom surface32A of the recessed portion32, there is a possibility that contact between the end face22A of one of the adjacent mouthpiece bodies22in the circumferential direction and the end face22B of the other of the adjacent mouthpiece bodies22in the circumferential direction is impeded, resulting in that a gap is formed between the end face22A and the end face22B. Such a phenomenon does not occur in the mouthpiece20of this embodiment.

Therefore, compared to the configuration having radial gaps between the recessed portions32and the protruding portions34as viewed from the axial direction, or the configuration having gaps between the end faces22A and the end faces22B as viewed from the axial direction, it is possible to improve the sealability in the fitting portions30. More specifically, even when a resin is impregnated into the reinforcing layer16by resin transfer molding (RTM), sealing can be performed to prevent leakage of the resin from the radially inner side to the radially outer side of the mouthpiece20.

When the mouthpiece20is attached to the open end portion14, the helical male screw portion29is formed by the screw grooves28formed on the outer peripheral portions of the mouthpiece bodies22. Therefore, by screwing the helical female screw portion19of the fastening part18into the male screw portion29, it is possible to attach the fastening part18to the open end portion14of the liner12(fastening part connecting process).

As described above, the mouthpiece20is configured such that the end face22A of one of the adjacent mouthpiece bodies22and the end face22B of the other of the adjacent mouthpiece bodies22are in contact with each other. Therefore, it is easy to perform dimension management of the inner diameter of the mouthpiece20, and even when the open end portion14is reduced in diameter, the mouthpiece20is not reduced in diameter. Consequently, it is possible to prevent the occurrence of a failure such that the fastening part18screwed to the mouthpiece20is loosened and detached.

Second Embodiment

Next, the configuration of a mouthpiece21according to a second embodiment will be described. The same signs are given to the same portions as those of the mouthpiece20according to the first embodiment, thereby omitting a detailed description thereof as appropriate.

As illustrated inFIGS. 10 and 11, a bulging portion38bulging in a generally circular shape as viewed from the axial direction is formed at a leading end portion of a protruding portion36(an end portion of the protruding portion36on the downstream side in the fitting direction of the protruding portion36to the recessed portion32) forming a fitting portion31of the mouthpiece21. The second embodiment differs from the first embodiment only in that the protruding portion36having the bulging portion38is provided.

As viewed from the axial direction, the diameter of the bulging portion38is set to be slightly greater than the width of the recessed portion32in the radial direction (the width of the recessed portion32in the radial direction is set to be slightly smaller than the diameter of the bulging portion38). Therefore, the bulging portion38is configured to be press-fitted into the recessed portion32. It is configured that a slight gap is formed in the radial direction between the protruding portion36excluding the bulging portion38and the recessed portion32.

Next, the operation of the pressure vessel10including the mouthpiece21according to the second embodiment configured as described above will be described. With respect to the operation common to that of the first embodiment, a description thereof will be omitted as appropriate.

As illustrated inFIGS. 10 and 11, the bulging portion38of the protruding portion36is press-fitted into the recessed portion32. Therefore, a gap in the radial direction is not formed between the recessed portion32and the bulging portion38. Further, a gap is formed between the bottom surface32A of the recessed portion32and a leading end surface38A of the bulging portion38. Therefore, like in the first embodiment, the end face22A of one of the adjacent mouthpiece bodies22in the circumferential direction and the end face22B of the other of the adjacent mouthpiece bodies22in the circumferential direction firmly contact with each other so that a gap is not formed also between the end face22A and the end face22B.

Therefore, compared to the configuration having radial gaps between the recessed portions32and the bulging portions38as viewed from the axial direction, or the configuration having gaps between the end faces22A and the end faces22B as viewed from the axial direction, it is possible to improve the sealability in the fitting portions31. In particular, the leading end portion of the protruding portion36is formed as the bulging portion38bulging in the generally circular shape as viewed from the axial direction, and therefore, after the bulging portion38is press-fitted into the recessed portion32, it is possible to constantly ensure the seal points in the radial direction against the recessed portion32.

As described above, the slight gap is formed in the radial direction between the protruding portion36excluding the bulging portion38and the recessed portion32. However, since the labyrinth structure is formed by the recessed portion32and the protruding portion36, a reduction in the sealability is suppressed. When the leading end portion of the protruding portion36is formed as the bulging portion38bulging in the generally circular shape, there is an advantage that even when the protruding portion36is inserted obliquely into the recessed portion32, the bulging portion38easily enters the recessed portion32.

While the pressure vessel10according to this embodiment has been described with reference to the drawings, the pressure vessel10according to this embodiment is not limited to that illustrated in the figures and can be changed in design as appropriate within the scope not departing from the gist of the disclosure. For example, it is satisfactory if the liner12has the cylindrical open end portion14on at least one end side of the liner12.

In the first embodiment, the leading end surface34A of the protruding portion34is not necessarily the arc surface formed to the arc shape as viewed from the axial direction. However, when the leading end surface34A of the protruding portion34is the arc surface, there is an advantage that the protruding portion34is allowed to easily enter the recessed portion32.

In the second embodiment, the bulging portion38of the protruding portion36is not limited to the configuration in which it is formed to the generally circular shape as viewed from the axial direction. It is satisfactory if the bulging portion38bulges at least in the radial direction so as to ensure the sufficient sealability, and, for example, the leading end surface38A of the bulging portion38may be formed as a flat surface.

The number of the mouthpiece bodies22forming the mouthpiece20is not limited to eight as illustrated. The number of the mouthpiece bodies22forming the mouthpiece20is changed in design as appropriate according to the outer diameter of the open end portion14(including the thickness of the reinforcing layer16), the length of each mouthpiece body22in the circumferential direction, and so on.

The gas to be filled into the liner12is not limited to hydrogen. For example, a gas such as helium or nitrogen can alternatively be filled into the liner12. The material of the reinforcing layer16is not limited to a carbon fiber reinforced resin (CFRP) as long as it is a fiber reinforced resin (FRP).

As long as it is configured that the end face22A of one of the adjacent mouthpiece bodies22in the circumferential direction and the end face22B of the other of the adjacent mouthpiece bodies22in the circumferential direction firmly contact with each other, a gap is not necessarily formed between the bottom surface32A of the recessed portion32and the leading end surface34A of the protruding portion34or the leading end surface38A of the bulging portion38.