INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2018-228535 filed on Dec. 5, 2018 including the specification, drawings and abstract is incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a pressure vessel manufacturing method.

2. Description of Related Art

Japanese Patent Application Publication No. 2018-519480 (JP 2018-519480 A) discloses a method of forming a pressure vessel by connecting tubes having a resin liner to each other through a flexible connector and then folding the flexible connector. This flexible connector has a corrugated part. A dry braiding is put on the resin liner, and resin is further applied to the braiding.

SUMMARY

In the field of manufacturing of a pressure vessel of which the outer side of a resin cylindrical connecting part is reinforced with a reinforcing part as in JP 2018-519480 A, there is a known method in which a connecting part that connects vessel main bodies to each other is pleated and curved, and then heated and pressurized to manufacture a pressure vessel. Curving the connecting part in this method causes a difference in the length in a curving direction of the connecting part between the inner side and the outer side of the curve, which in turn causes a difference in the state of an inner surface of the connecting part between these sides.

More particularly, on the outer side of the curve, the length in the curving direction of the connecting part is long and the pleated part is stretched out in the curving direction, leaving a small clearance between ridges of the pleated part and the reinforcing part. Conversely, on the inner side of the curve, the length in the curving direction of the connecting part is short and the pleated part is less stretched out in the curving direction, so that a larger space is left between ridges of the pleated part and the reinforcing part than on the outer side of the curve. A large space between the ridges of the pleated part and the reinforcing part means a high degree of freedom for deformation of the pleated part. Thus, when the connecting part is curved and the inside of the curved connecting part is pressurized, the part of the liner on the inner side of the curve may become prone to deformation compared with the part thereof on the outer side of the curve. There is room for improvement here.

In view of this fact, the present disclosure aims to devise a pressure vessel manufacturing method that can ensure that when a pleated tubular body and a reinforcing part are curved and the inside of the curved tubular body is pressurized, a part of the tubular body on the inner side of the curve is less prone to deformation.

A pressure vessel manufacturing method of a first aspect of the present disclosure includes: molding a resin tubular body that connects one vessel main body and another vessel main body to each other, with a pleated part formed at least at part of the tubular body in an axial direction; forming a reinforcing part that reinforces the tubular body on the outer circumferential side of the tubular body; curving the tubular body and the reinforcing part such that an axis of the tubular body draws a curved line; and heating the tubular body and the reinforcing part while pressurizing the inside of the curved tubular body. In the molding the tubular body, the height of first pleats of the pleated part that are disposed on the inner side of the curve relative to the axis is set to be smaller than the height of second pleats of the pleated part that are disposed on the outer side of the curve relative to the axis.

In the pressure vessel manufacturing method of the first aspect, the height of the first pleats is set to be smaller than the height of the second pleats. This allows the first pleats to be stretched out along the curving direction at a part of the tubular body on the inner side of the curve when the tubular body and the reinforcing part are curved. In other words, the clearance between ridges of the first pleats and the reinforcing part is reduced. As a result, the area of contact between the first pleats and the reinforcing part is increased and the degree of freedom for deformation of the first pleats is reduced. Thus, this method can ensure that when a pleated tubular body and a reinforcing part are curved and then the inside of the curved tubular body is pressurized, the part of the tubular body on the inner side of the curve is less prone to deformation.

In a pressure vessel manufacturing method of a second aspect of the present disclosure, the amount of a pressure applied to pressurize the inside of the tubular body may be set such that the first pleats after heating form a curved part extending along the reinforcing part.

In the pressure vessel manufacturing method of the second aspect, a predetermined pressure is applied in the process of heating the tubular body while pressurizing the inside of the tubular body, so that not only the second pleats but also the first pleats are deformed so as to have a smaller height after heating. Moreover, the first pleats after heating form a curved part extending along the reinforcing part. Thus, applying the predetermined pressure to the first pleats and the second pleats can cause not only the second pleats but also the first pleats to assume a shape extending along the axial direction. As a result, the area of contact between the first pleats and the reinforcing part is increased compared with when a low pressure is applied, and the clearance between the first pleats and the reinforcing part after heating can be reduced accordingly.

The present disclosure can ensure that when a pleated tubular body and a reinforcing part are curved and then the inside of the curved tubular body is pressurized, the part of the tubular body on the inner side of the curve is less prone to deformation.

