JP2006220284A - Pressure vessel and design method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a pressure vessel which is constituted more rationally so as to ensure pressure resistance and realize effective utilization of an installation space. <P>SOLUTION: The invention provides the pressure vessel including a tubular body 10 for storing a stored object therein which has a non-circular cross-sectional peripheral shape, the tubular body having a wall thickness varied according to the part so that the stress generated in the tubular body can be equalized, and also provides a method of manufacturing the pressure vessel. For the purpose of equalizing the stress generated in the tubular body, a certain wall thickness calculation zone corresponding to the cross-sectional shape of the tubular body is determined so as to calculate an external stress and an internal stress generated in the wall thickness calculation zone by the internal pressure and to set the wall thickness of the tubular body in the wall thickness calculation zone at a value corresponding to a larger one of the external and internal stresses. Further, in the pressure vessel having the tubular body with a polygonal cross-sectional peripheral shape, the tubular body is provided with internal walls 12 directly connecting intermediate portions of two sides constituting each corner of the polygonal tubular body. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a pressure vessel including a tubular body that accommodates an object to be contained therein.

  As a pressure vessel filled with a high-pressure object (liquid, gas, powder, hydrogen storage alloy, etc.), a container formed by closing both ends of a tubular body is known. The object to be accommodated is accommodated inside the tubular body. The cross-sectional shape of the tubular body is generally circular. The wall thickness of the tubular body is set uniformly. Patent Document 1 describes a pressure vessel provided with a tubular body having a circular cross-sectional shape. The pressure vessel described in Patent Document 1 is obtained by reinforcing the outer periphery of a circular tubular body.

Moreover, considering the increase in capacity at a limited installation location of the pressure vessel, a tubular body having a circular cross-sectional shape has a disadvantage that a dead space is generated. In this regard, Patent Documents 2 and 3 describe a pressure vessel using a tubular body having a rectangular cross-sectional outer periphery. According to such a pressure vessel, it is possible to cope with the problem of dead space.
Japanese Patent Laid-Open No. 9-42595 Japanese Patent No. 3030269 JP 2004-225772 A

  Now, it is important to secure a large volume of the pressure vessel in a small space, and further contrivance is required for the tubular body described above.

  In particular, in recent years, fuel cell vehicles have been put into practical use in order to reduce exhaust gas, and further rationalization of pressure vessels used as hydrogen tanks for fuel cells is required. For example, there is a circumstance that a hydrogen tank cannot be excessively pressurized to ensure safety. In particular, there are cases where the upper limit of pressure is set by law. In this regard, as in Patent Document 1, by reinforcing the outer periphery of a tubular body having a circular cross-sectional shape, the pressure resistance is improved, but the volume has a limit due to pressure limitation. In addition, the manufacturing cost is high. After all, it can be said that increasing the volume by using the above-described dead space is one of the major problems at present.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a pressure vessel that is more rationally configured to achieve pressure resistance and to effectively use an installation space.

  The invention described in claim 1 of the present application includes a tubular body that accommodates an object to be contained therein, and in a pressure vessel in which the outer peripheral shape of the cross section of the tubular body is non-circular, the stress generated in the tubular body is uniform. The pressure vessel has a configuration in which the wall thickness of the tubular body is set to a different thickness depending on the part.

  In the invention described in claim 2 of the present application, in order to equalize the stress generated in the tubular body in claim 1, a predetermined wall thickness calculation section corresponding to the cross-sectional shape of the tubular body is set and The outer surface stress and the inner surface stress generated in the wall thickness calculation section are obtained, and the wall thickness of the tubular body in the wall thickness calculation section is set to a thickness corresponding to the larger value of the outer surface stress and the inner surface stress. This is a pressure vessel having the structure described above.

  The invention described in claim 3 of the present application is the pressure vessel according to claim 1 or 2, wherein the tubular body is partitioned into a plurality of parts.

  The invention described in claim 4 of the present application includes a tubular body that accommodates an object to be contained therein, and a pressure vessel in which a cross-sectional outer peripheral shape of the tubular body exhibits a polygon, wherein the tubular body is the polygon. It is the pressure vessel of the structure provided with the internal wall which connects directly the intermediate part of 2 sides which form the corner | angular of this.

  The invention described in claim 5 of the present application is the pressure according to claim 4, wherein the wall thickness of the tubular body is set to a different thickness depending on the part so that the stress generated in the tubular body is equalized. It is a container.

  In the invention described in claim 6 of the present application, in order to equalize the stress generated in the tubular body in claim 5, a predetermined wall thickness calculation section corresponding to the cross-sectional shape of the tubular body is set and The outer surface stress and the inner surface stress generated in the wall thickness calculation section are obtained, and the wall thickness of the tubular body in the wall thickness calculation section is set to a thickness corresponding to the larger value of the outer surface stress and the inner surface stress. This is a pressure vessel having the structure described above.

  The invention described in claim 7 of the present application is the pressure vessel according to any one of claims 1 to 6, wherein a reinforcing means is provided on the outer periphery of the tubular body.

  The eighth aspect of the present application provides a tubular body that accommodates an object to be contained therein, and in a method for designing a pressure vessel in which a cross-sectional outer peripheral shape of the tubular body exhibits a non-circular shape, stress generated in the tubular body is equalized In this method, the wall thickness of the tubular body is set to a different thickness depending on the site, a predetermined wall thickness calculation section corresponding to the cross-sectional shape of the tubular body is set, and the wall is determined by internal pressure. The outer surface stress and the inner surface stress generated in the thickness calculation section are obtained, and the wall thickness of the tubular body in the wall thickness calculation section is set to a thickness corresponding to the larger value of the outer surface stress and the inner surface stress. This is a pressure vessel design method.

  According to the present invention, it is possible to obtain a pressure vessel whose volume is increased by effectively using the installation space while ensuring pressure resistance.

  A first embodiment of the present invention will be described below with reference to the drawings. A pressure vessel 1 of this example shown in FIG. 1 includes a tubular body 10 that accommodates compressed gas that is an object to be contained therein, and end members 20 that are respectively attached to both ends of the tubular body 10. . The tubular body 10 of this example is formed by extruding an aluminum alloy. The end member 20 closes both ends of the tubular body 10, and its form is not particularly limited. A compressed gas inlet / outlet port is provided in the end member 20.

  FIG. 2 is a cross-sectional view taken along the line XX in FIG. 1 and is an explanatory diagram showing the cross-sectional shape of the tubular body 10. As shown in the figure, the tubular body 10 of the present example has an outer peripheral shape of a cross section of a square. Reference numeral 11 in the figure denotes a compressed gas storage unit. That is, the volume of the compressed gas is ensured by making the installation space of the pressure vessel 1 noncircular with little dead space.

  Here, the problem in the case of a non-circular shape is that the wall thickness becomes thick when the pressure resistance is secured, the wall thickness becomes heavy at a constant wall thickness, and the volume decreases. In this example, the wall thickness of the tubular body 10 is set to a different thickness depending on the part so that the stress generated in the tubular body 10 is equalized, while ensuring sufficient pressure resistance against internal pressure, Meat is removed to increase volume and reduce weight. Specifically, when equalizing the stress generated in the tubular body 10, a predetermined wall thickness calculation section corresponding to the cross-sectional shape of the tubular body 10 is set, and the external surface stress and the internal surface generated in the wall thickness calculation section by the internal pressure I'm looking for stress. The wall thickness of the tubular body 10 in the wall thickness calculation section is set to a thickness corresponding to the larger value of the outer surface stress and the inner surface stress. In the present application, the wall thickness calculation section refers to a section set in order to calculate the thickness of the wall separating the inner side and the outer side of the tubular body 10. The wall thickness of the tubular body 10 is calculated on the assumption of a load generated by the internal and external differential pressure. In the case of this example, the wall thickness calculation section is a range indicated by an arrow A in the figure, and is set to correspond to each of the four sides of a regular square.

  It can be assumed that a load distribution as shown in FIG. 3 occurs in the wall thickness calculation section. In addition, in the distribution of the resultant stress due to these loads, the pressure resistance can be ensured by setting the wall thickness so that the maximum value is the allowable stress. However, with a constant wall thickness corresponding to the maximum stress as in the prior art, there is a portion where the stress is small and the strength is sufficient. Therefore, if the wall thickness of the tubular body 10 is set so that the combined stress in all parts is equal to the allowable stress, the pressure resistance is ensured and the structure is not wasted. The distribution of the resultant stress varies in the thickness direction from the outer surface to the inner surface, but since it is the maximum on either the outer surface or the inner surface, the outer surface stress and the inner surface stress are calculated for each part in the circumferential direction, whichever is greater The wall thickness may be set so as to correspond to the value of.

  FIG. 4 is a graph showing the wall thickness corresponding to the outer surface stress and the inner surface stress generated in the wall thickness calculation section. The wall thickness of the tubular body 10 is set to a thickness corresponding to the larger value of the outer surface stress and the inner surface stress. That is, if the outer peripheral side of the tubular body 10 is flattened, the cross-sectional shape on the side of the accommodating portion 11 is a curved shape indicated by a circle in the graph. The cross-sectional contour of the accommodating portion 11 has a shape formed by continuously forming such a curved shape in an annular shape. According to such a configuration, the thickness of the tubular body 10 can be set without waste while ensuring the pressure resistance of the pressure vessel 1. In addition, the stress generated in the tubular body is not completely equal in a portion where the shape change is large, such as a corner portion or an intersection between the outer wall and the inner wall, and an appropriate margin should be given with priority given to pressure resistance. Is desirable. About the shape of the cross-sectional outline of the accommodating part 11, it is good to perform further FEM analysis etc. and to confirm and correct | amend a calculation result.

  The configuration of each part in the present example can be appropriately changed in design within the technical scope described in the claims, and of course is not limited to that illustrated in the drawings. Moreover, although the tubular body 10 of this example is produced by extrusion molding, the manufacturing method is not particularly limited. For example, an injection-molded resin tubular body can be used according to the performance and application of the pressure vessel 1.

  Next, a second embodiment of the present invention will be described with reference to FIG. As shown in the figure, the tubular body 10 of the present example is formed by dividing the accommodating portion 11 into a plurality of portions. The wall thickness calculation section is set for each storage unit. Other basic configurations are the same as those in the above-described embodiment. By partitioning the accommodating portion 11 in this way, the wall thickness can be set thin while ensuring the pressure resistance of the pressure vessel 1, and as a result, the volume can be increased and the weight can be reduced.

  Next, a third embodiment of the present invention will be described with reference to FIG. The tubular body 10 of this example is obtained by further subdividing the accommodating portion 11. Other basic configurations are the same as those in the above-described embodiment. According to such a configuration, the volume can be further increased and the weight can be reduced.

  Next, a fourth embodiment of the present invention will be described with reference to FIGS. The tubular body 10 of the present example includes an inner wall 12 that directly connects intermediate portions of two sides forming a square corner. In the illustrated example, the inner wall 12 linearly connects two intermediate portions. According to such an inner wall 12, since the total extension of the inner wall in the cross section of the tubular body 10 can be shortened, the volume of the pressure vessel 1 can be increased and the weight can be reduced. In addition, when extrusion molding becomes difficult, as shown in FIG. 8, it is good to join the tubular body structural member 10a each extruded and to comprise the tubular body 10. FIG. According to such a configuration, it is possible to manufacture a tubular body having a complicated shape relatively easily.

  Next, a fifth embodiment of the present invention will be described with reference to FIG. In the tubular body 10 shown in the fourth embodiment, the walls of the tubular body 10 are equalized so that the stresses generated in the tubular body 10 are equalized with the ranges indicated by arrows A, B, and C in the figure as the wall thickness calculation section. The thickness is set to a different thickness depending on the part. In this way, by eliminating the waste of the tubular body 10, the volume can be further increased and the weight can be reduced.

  Next, a sixth embodiment of the present invention will be described with reference to FIG. The tubular body 10 of this example is provided with reinforcing means on the outer periphery thereof. The reinforcing means of this example is provided by attaching a high-strength member to the outer peripheral surface of the tubular body 10. As the high-strength member 13, a member obtained by bundling carbon fibers is employed. Or an iron plate etc. is also employable. Other basic configurations are the same as those in the above-described embodiment. According to such a configuration, the pressure resistance of the pressure vessel 1 can be further improved. In particular, the wall thickness of the tubular body 10 can be further reduced.

  The inventor of the present application verified the performance of the pressure vessel 1 of each example described above together with the comparative samples shown in FIGS. 14 and 15 are graphs showing the verification data. FIG. 14 is a graph showing the space efficiency of the pressure vessel 1. The space efficiency is an efficiency representing how much compressed gas can be accommodated in the installation space occupied by the pressure vessel 1. The vertical axis in the figure is the filling amount per unit space, that is, the specific space filling amount, and the larger this value, the higher the space efficiency and the larger the volume can be secured. FIG. 15 is a graph showing the weight efficiency of the pressure vessel 1. The weight efficiency is an efficiency representing how much compressed gas can be accommodated with respect to the weight of the pressure vessel 1. The vertical axis of the figure is the filling amount per unit weight, that is, the specific weight filling amount, and the larger this value, the higher the weight efficiency and the lighter the weight. This verification was performed assuming an installation space of 200 mm × 200 mm × 800 mm. That is, the design of the pressure vessel 1 may be performed based on a predetermined installation space. Of course, the size and shape of the installation space are not limited to this.

  The tubular body 100 in FIG. 11 as a comparative sample has a circular cross-sectional shape. The outer diameter is set equal to the length of one side of the regular square in the first embodiment described above. The accommodating part 101 is circular. Moreover, the tubular body 100 of FIG. 12 is formed by providing carbon fibers 102 on the outer periphery. Other configurations are the same as those shown in FIG. Further, in FIG. 13, the outer peripheral shape of the cross section is a regular square, and the wall thickness of the tubular body 100 is set to be uniform.

  In each graph, the example of the comparative sample shown in FIG. 11 is “circular aluminum”, the example of the comparative sample shown in FIG. 12 is “circular composite”, and the example of the comparative sample shown in FIG. The first embodiment of the present invention shown in FIG. 2 is “Square wall thickness optimization”, the second embodiment of the present invention shown in FIG. 5 is “Square vertical and horizontal ribs divided into two”, and FIG. The third embodiment of the present invention shown is "square vertical and horizontal ribs divided into three", the fifth embodiment of the present invention shown in FIG. 9 is "square diagonal rib aluminum", and the sixth embodiment of the present invention shown in FIG. It is referred to as “square diagonal rib composite”.

  As shown in FIG. 11, when a circular tubular body is composed of only an aluminum alloy, the weight efficiency is good for use at a low pressure, but both the space efficiency and the weight efficiency are lowered when trying to withstand the high pressure. That is, the volume is reduced and the weight is increased.

  On the other hand, as shown in FIG. 12, if the carbon fiber is used for reinforcement, both space efficiency and weight efficiency are improved, and it is also suitable for high pressure. In particular, the improvement in weight efficiency is remarkable, and the effect on weight reduction is great.

  On the other hand, as shown in FIG. 13, when the tubular body is made to have a uniform square wall thickness in order to use a wasteful space due to a circle, the wall thickness becomes thick in order to ensure pressure resistance. As a result, both the weight efficiency and the volume are smaller and the weight is heavier than the circular one.

  According to the first embodiment of the present invention shown in FIG. 2, both space efficiency and weight efficiency are improved from those shown in FIG. 13, and both space efficiency and weight efficiency are improved as shown in FIG. The advantage of being large and lightweight was obtained.

  According to the second embodiment of the present invention shown in FIG. 5, the space efficiency and the weight efficiency are further improved as compared with those shown in FIG.

  According to the third embodiment of the present invention shown in FIG. 6, both space efficiency and weight efficiency are further improved as compared with that shown in FIG. 5, and the volume is larger and lighter as the accommodating portion 11 is subdivided. However, the degree of performance improvement is small.

  According to the fifth embodiment of the present invention shown in FIG. 9, a remarkable performance improvement is achieved as compared with that shown in FIG. The space efficiency not only exceeds that shown in FIG. 11, but also exceeds that shown in FIG. 12 at low pressure. The weight efficiency is higher than that shown in FIG. 11 except for extremely low pressure. In other words, the advantages of larger volume and light weight were obtained.

  According to the sixth embodiment of the present invention shown in FIG. 10, further performance improvement is achieved with respect to that shown in FIG. The space efficiency exceeds that shown in FIG. 12, and is the largest of the embodiments. The weight efficiency exceeds that shown in FIG. 11 even at low pressure. In addition, there is no reduction in efficiency even at high pressure, and the characteristics are suitable for use at high pressure.

  The tubular body 10 may be designed in consideration of the advantages of each configuration based on such verification data while taking into account the use conditions. As its effect, a more excellent pressure vessel can be obtained, and the manufacturing cost can be reduced. In particular, depending on how the pressure vessel is used, its heat dissipation may be important. In this regard, by setting the wall thickness of the tubular body 10 to a different thickness depending on the part, or by dividing the inside of the tubular body 10, the contact area between the tubular body 10 and the object to be accommodated is increased. Since it increases, there exists an advantage used as the pressure vessel excellent also in heat dissipation.

  The pressure vessel of the present invention can be suitably used as a hydrogen tank mounted on a fuel cell vehicle. It can also be used as a CNG storage tank mounted on a CNG vehicle, a hydrogen stand storage tank, a household LPG tank, a fire extinguisher, or the like.

It is explanatory drawing which concerns on the Example of this invention and shows the longitudinal cross-section of a pressure vessel. It is explanatory drawing which concerns on the Example of this invention and shows the cross-sectional shape of a tubular body. It is a graph which concerns on the Example of this invention and shows the load distribution which arises in a wall thickness calculation area. It is a graph which shows the wall thickness which concerns on the Example of this invention and respond | corresponds to the external surface stress and internal surface stress which arise in a wall thickness calculation area. It is explanatory drawing which concerns on the Example of this invention and shows the cross-sectional shape of a tubular body. It is explanatory drawing which concerns on the Example of this invention and shows the cross-sectional shape of a tubular body. It is explanatory drawing which concerns on the Example of this invention and shows the cross-sectional shape of a tubular body. It is explanatory drawing which concerns on the Example of this invention and shows the cross-sectional shape of a tubular body structural member. It is explanatory drawing which concerns on the Example of this invention and shows the cross-sectional shape of a tubular body. It is explanatory drawing which concerns on the Example of this invention and shows the cross-sectional shape of a tubular body. It is explanatory drawing which concerns on the other Example different from this invention, and shows the cross-sectional shape of a tubular body. It is explanatory drawing which concerns on the other Example different from this invention, and shows the cross-sectional shape of a tubular body. It is explanatory drawing which concerns on the other Example different from this invention, and shows the cross-sectional shape of a tubular body. It is a characteristic graph of the allowable internal pressure-specific space filling amount according to the embodiment of the present invention. It is a characteristic graph of the allowable internal pressure-specific weight filling amount according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pressure vessel 10 Tubular body 10a Tubular body structural member 11 Accommodating part 12 Internal wall 13 High-strength member 20 End member

Claims (8)

In a pressure vessel comprising a tubular body that accommodates an object to be contained therein, wherein the tubular body has a non-circular cross-sectional outer peripheral shape,
A pressure vessel characterized in that the wall thickness of the tubular body is set to a different thickness depending on the site so that the stress generated in the tubular body is equalized.   In equalizing the stress generated in the tubular body, a predetermined wall thickness calculation section corresponding to the cross-sectional shape of the tubular body is set, and external stress and internal stress generated in the wall thickness calculation section by internal pressure are obtained, The pressure vessel according to claim 1, wherein the wall thickness of the tubular body in the wall thickness calculation section is set to a thickness corresponding to a larger value of the outer surface stress and the inner surface stress.   The pressure vessel according to claim 1 or 2, wherein the inside of the tubular body is divided into a plurality of sections. In the pressure vessel comprising a tubular body that accommodates an object to be contained therein, and the outer circumferential shape of the tubular body having a polygonal shape,
The pressure vessel according to claim 1, wherein the tubular body includes an inner wall that directly connects intermediate portions of two sides forming the corners of the polygon.   The pressure vessel according to claim 4, wherein the wall thickness of the tubular body is set to a different thickness depending on the site so that the stress generated in the tubular body is equalized.   In equalizing the stress generated in the tubular body, a predetermined wall thickness calculation section corresponding to the cross-sectional shape of the tubular body is set, and external stress and internal stress generated in the wall thickness calculation section by internal pressure are obtained, 6. The pressure vessel according to claim 5, wherein a wall thickness of the tubular body in a wall thickness calculation section is set to a thickness corresponding to a larger value of the outer surface stress and the inner surface stress.   The pressure vessel according to any one of claims 1 to 6, wherein reinforcing means is provided on an outer periphery of the tubular body. In the method for designing a pressure vessel, comprising a tubular body that accommodates an object to be contained therein, and the tubular body has a non-circular cross-sectional outer peripheral shape.
The method is to set the wall thickness of the tubular body to a different thickness depending on the part so that the stress generated in the tubular body is equalized,
A predetermined wall thickness calculation section corresponding to the cross-sectional shape of the tubular body is set, an external stress and an internal stress generated in the wall thickness calculation section by internal pressure are obtained, and the wall thickness of the tubular body in the wall thickness calculation section is A method of designing a pressure vessel, wherein the thickness is set to a thickness corresponding to a larger value of the outer surface stress and the inner surface stress.

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