JPH0193700A - Laminated pressure vessel - Google Patents

Abstract

PURPOSE:To improve operating efficiency of vessel wall members by forming a pressure vessel as a laminated pressure vessel consisting of laminated plural vessel-shaped layers, and radially and evenly distributing the stress generated in the vessel wall by specifying the apparent elastic moduli of each vessel-shaped layer. CONSTITUTION:When a cavity 11 of a laminated pressure vessel 11 is filled with a high pressure fluid, the fluid pressure of the fluid acts on an alloyed vessel 12 so as to enlarge the diameter of the vessel 12, and thus to produce stress in the vessel 12. The stress in the vessel 12 further acts on a reinforcing layer 13 closely contacted with the vessel 12 so as to enlarge the diameter of the reinforcing layer 13, and thus to generate stress in the reinforcing layer 13. However, for the laminated pressure vessel 11, the apparent elastic modulus of the vessel 12 on the high pressure side is about one-half smaller than that of the reinforcing layer 13 on the low pressure side, so that the stress generated in the vessel 12 is greatly reduced.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a laminated pressure vessel, for example, a pressure vessel for fluid machinery,
Pressure vessels that store fluids such as high-pressure liquids or gases, such as propane cylinders, or scuba diving tanks and diving equipment used in shallow or deep sea, and that store fluids such as high-pressure liquids or gases, as well as high external pressure due to water pressure. It relates to a pressure vessel in which

(Prior Art) Recently, fluid pressure such as hydraulic pressure or atmospheric pressure used in fluid machines has been increased, and pressure vessels (hereinafter referred to as
Containers with high pressure resistance are used. In these containers, the high positive pressure fluid contained within the container presses the inner surface of the container at high pressure, so a container that can withstand this pressing force is required. In addition, for containers used in fluid machines used under high external pressure in the deep sea, high external pressure acts as the water depth increases, and containers with high pressure resistance against external pressure are used. The pressing force of the high external pressure against the container wall corresponds to the fact that a high negative pressure fluid is accommodated in the container. Hereinafter, a container for a positive pressure fluid will be explained as a representative example.

Conventionally, the pressure resistance of containers has been increased by increasing the wall thickness of the container. That is, in the case of metal containers, the container is made into a double pipe or the thickness of the container wall is increased, and in the case of hoses, the number of braided layers of the hose is increased.

(Problems to be Solved by the Invention) However, when the wall thickness of the container is increased, there is a problem that the amount of components for the container wall increases, the weight of the container increases, and the price increases.

Therefore, the present invention increases the usage efficiency of the members of the vessel wall by uniformly distributing the stress generated in the vessel wall of the pressure vessel in the direction perpendicular to the vessel wall surface, that is, in the thickness direction of the vessel,
It is an object of the present invention to provide a laminated pressure vessel that increases the pressure resistance of the vessel and reduces the increase in the weight and price of the vessel.

(Means for Solving the Problems) The present inventors have conducted various studies regarding the thickness of the container wall, the failure phenomenon during pressure increase, the fatigue failure of the container, etc. regarding containers for storing fluids with high fluid pressure.

As a result, even if the thickness of the wall of a container made of a single member is increased, there is no significant improvement in the performance against fatigue failure of the container. In other words, it has been found that the pressure resistance of the container cannot be improved simply by increasing the thickness of the container wall. On the other hand, container failure often occurs mainly on the inside of the container, which means that the stress applied to the inside of the container is higher than the stress applied to the outside of the container, and stress increases in the thickness direction of the container. This shows that the distribution is not uniform. moreover,
We studied the relationship between the stress in the thickness direction of the container and the components of the container, and found that by making the stress distribution of the container uniform in the thickness direction of the container, the pressure resistance performance of the container can be significantly improved.

In order to make the stress distribution of the container uniform in the thickness direction, the present inventors have proposed that the container is made of a laminated pressure vessel in which a plurality of container-like layers are laminated, and that at least one of the container-like layers is It has been found that this method can be implemented by changing the elastic modulus of the container-like layer formed by a linear member formed in a spiral shape. The vessel wall stress of the laminated pressure vessel will be explained below.

In general, when a circular pipe with a wall with an average radius R expands in diameter due to the internal pressure inside the pipe and is displaced by U in the radial direction, the circumferential strain e, which is the strain in the circumferential direction at this time, is calculated by the following formula % formula % (1 ) becomes. According to Hooke's law, the circumferential stress S, which is the stress in the circumferential direction, is expressed by the following formula (%) (2) where E is the apparent elastic modulus of the vessel wall in the circumferential direction.

Then, according to equations (1) and (2) above, the circumferential stress S
can be expressed by the following formula % formula % (3). Further, if the tensile strength of the vessel wall is expressed as σ and both sides of equation (3) are divided by the tensile strength σ, the following equation is obtained.

S/σ-E/σ・U/R... (4) In a container made of a single member on which internal pressure acts, destruction of the container mainly occurs inside the container wall. This is because the circumferential stress S inside the vessel wall becomes maximum. Therefore, in order to avoid this destruction, the circumferential stress S in the container wall is dispersed,
It is desirable to make the circumferential stress S uniform in the thickness direction of the vessel wall.

In the circular cross-sectional part of the laminated pressure vessel, any two inner and outer vessel shapes constituting the laminated pressure vessel Jiii
The circumferential stress Si, Sj acting on +j is
Since the above-mentioned equation (3) holds true for j, the following relationship exists. Here, E in E Jl σi
,σj.

Ui, Uj, Ri, and Rj are container-like layers i, respectively.

j is the elastic modulus, tensile strength, displacement, and average radius, and Ri<R
There is a relationship of j.

Therefore, in a laminated pressure vessel as well as in the case of a vessel made of a single member, in order to avoid damage to the inside of the vessel, as shown in Fig. 3, the peak of the circumferential stress Sp It is desirable to reduce the circumferential stress S in Sj (hereinafter simply referred to as stress) in the radial direction, which is the thickness direction of the container, and to disperse the circumferential stress within the container.
In other words, in equation (5), it is desirable that ((S j/σj)÷(Si/σi)) be close to 1.

In a laminated pressure vessel to which internal pressure acts, in order to make the stress uniform in the thickness direction of the vessel, in equation (4), Ri
<Rj, so the elastic modulus Ei, E of the member of each container layer
The elastic modulus Ei inside jO and inside the container may be made small.

That is, when internal pressure acts on the container, for example, when a positive pressure fluid is introduced into the container and the fluid pressure is applied, the apparent elastic modulus Ei of the member of the container-like layer inside the container is It may be made smaller than the apparent elastic modulus Ej of the member of the container-like layer.

In addition, when external pressure acts on the container, for example, when negative pressure fluid is stored in the container due to external pressure from outside the container and fluid pressure acts, the apparent elastic modulus Ej of the member of the container-like layer outside the container may be made smaller than the apparent elastic modulus Ei of the member of the container-like layer inside the container.

In this way, the stresses St and Sj are distributed in the container-like layer member in the thickness direction of the container, the stress peak inside the container is reduced, and the stress is averaged and the pressure resistance of the container is increased. Performance will improve.

The present inventors further conducted intensive research and arrived at the present invention.

That is, the laminated pressure vessel according to the present invention is a laminated pressure vessel in which a plurality of container-like layers are laminated to form a cavity in which a fluid whose pressure is more positive than the external pressure of the container or a fluid whose pressure is negative than the external pressure of the container is housed. One container-like layer is made of a linear member formed in a spiral shape, and when the fluid pressure of the fluid acts on the laminated pressure vessel, the apparent elastic modulus of the container-like layer on the high pressure side is changed to the low pressure side. It is characterized by having a lower apparent elastic modulus than that of the lamina.

Here, the apparent elastic modulus is the elastic modulus in the circumferential direction corresponding to the expansion or contraction of the diameter of the circular cross-sectional portion of the container when fluid pressure is applied within the container. When the container layer is a single member such as a metal container, the elastic modulus is the same as that of the single member. When the container layer is formed by spirally forming a linear member such as a wire, the linear member is arranged at a driving angle of about 54.7° with respect to the central axis of the container layer. In this case, the apparent elastic modulus E of the container layer in the circumferential direction is approximately half of the elastic modulus E of the linear member in the tensile force direction.

Further, in the present invention, the driving angle of the linear member is not changed in order to change the apparent elastic modulus of the container-like layer. This is because if the driving angle is changed, the fatigue resistance performance decreases. The driving angle of the container-like layer in the present invention is approximately 54.7°, regardless of the material used.

(Function) A high-pressure fluid having a positive pressure relative to the external pressure of the container is stored in the cavity inside the stacked pressure vessel, and the fluid pressure acts on the vessel wall.

First, the fluid pressure acts on the container-like layer on the high-pressure side and generates stress in the container wall, and then the container-like layer on the high-pressure side acts on the laminated container-like layer on the low-pressure side, causing stress in the vessel wall. Generates stress within the wall. In the laminated pressure vessel of the present invention, the apparent elastic modulus of the container-like layer on the high-pressure side is made smaller than the apparent elastic modulus of the container-like layer on the low-pressure side. The stress decreases as the elastic modulus decreases. Conversely, the stress generated in the container-like layer on the low-pressure side increases as the elastic modulus increases. Therefore, the stress generated in the laminated pressure vessel is distributed in a substantially -like manner in the radial direction of the vessel.

Then, the peak stress generated on the inner wall of the container is reduced and the stress is averaged out. Therefore, the pressure resistance of the laminated pressure vessel is significantly increased.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1.2 is a diagram showing an embodiment of a laminated pressure vessel according to the present invention.

First, the configuration will be explained. In Figure 1.2, 1
1 is a laminated pressure vessel, and the laminated pressure vessel 11 is an alloy vessel 12 made of an aluminum alloy as two vessel-like layers.
A reinforcing layer 13 is laminated on the outside of the alloy container 12 so as to be in close contact with the alloy container 12 and cover the alloy container 12. A coating member 16 made of synthetic resin such as epoxy resin is provided on the outside of the reinforcing layer 13 so as to cover the outer surface of the reinforcing layer 13 . A cavity 17 is formed inside the alloy container 12, and a fluid can be stored in the cavity 17. The cavity 17 communicates with the outside through an opening 12a provided in a part of the peripheral wall of the alloy container 12. The reason why the alloy container 12 made of metal is provided inside the laminated pressure vessel 11 is that when the fluid stored in the cavity 17 is gas, the alloy container 12 is superior to all synthetic resins in permeation resistance to gas. This material may be made of a material with low gas permeability, such as glass. Laminated pressure vessel
A high-pressure fluid having a positive pressure with respect to the external pressure of the container is stored in the cavity 17 inside the laminated pressure vessel 11.
When acted upon, the alloy container 12 becomes the high pressure side, and the reinforcing layer 13 becomes the low pressure side. The reinforcing layer 13 is made of carbon fibers 18 which are linear members, and the carbon fibers 18 are brought into close contact with each other in the circumferential direction to form a spiral shape at a static angle of approximately 54.7° with respect to the axis of the laminated pressure vessel 11. The wires are wound so as to have a predetermined thickness, and are laminated in layers in the radial direction in close contact with each other. Carbon fiber in each layer 1
For example, the direction of the spiral of No. 8 is the S direction for the 1.3rd layer and the Z direction for the 2.4th layer, and is alternated in each layer. The first to fourth layers are the reinforcing layer 13 as a whole.
It consists of

In the cylindrical portion 11a at the axial center of the laminated pressure vessel 11, as shown in FIG. 2, the outer diameter of the alloy vessel 12 is ! ,
is 160 Tsuru, the inner diameter I) + zb is 1201 Tsuru, the outer diameter DI311 of the reinforcing layer 13 is 180 Tsuru, and the inner diameter DI3 is 1
60n, which is the same as the outer diameter DI2m of the alloy container 12. The coating member 16 has a thickness Do of 2.5 +u.

The elastic modulus of the alloy container 12 in the axial direction is 7.200 kg f
7 mm'', and the apparent elastic modulus E in the circumferential direction of the alloy container 12, ! is the same as the elastic modulus in the axial direction, 200 kg.
f /mn+". The reinforcing layer 13 is made of carbon fiber 18
is formed in a spiral shape, and the resting angle is approximately 54.7°.
Therefore, the apparent elastic modulus E13 of the reinforcing layer 13 in the circumferential direction is 1, which is half of the tensile elastic modulus of the carbon fiber 18 of 26.000 kg f /ms.
It is 3.000 kg f /mmz.

That is, the apparent elastic modulus El! of the aluminum container, which is the inner container-like layer on the high-pressure side of the laminated pressure vessel 11, is is smaller than the apparent elastic modulus ELS of the reinforcing layer 13, which is the outer container-like layer on the low-pressure side of the laminated pressure vessel 11, and is about 1/
It is 2.

Next, the effect will be explained.

When a high-pressure fluid is stored in the cavity 17 of the laminated pressure vessel 11, the fluid pressure of the fluid acts on the alloy vessel 12 and the alloy vessel 1
When trying to increase the diameter of alloy container 12, stress S
The stress SI of the 0 alloy container 12 that generates +z! further acts on the reinforcing layer 13 that is in close contact with the alloy container 12, and the reinforcing layer 1
When trying to increase the diameter of the reinforcing layer 13, stress S1
Generates 3. However, the laminated pressure vessel 1 of the present invention
1 is the apparent elastic modulus EI of the alloy container 12 on the high pressure side! is the apparent elastic modulus EI of the reinforcing layer 13 on the low pressure side! smaller,
Since the stress S generated in the alloy container 12 is approximately 1/2,
! decreases significantly. Therefore, the stress Sl! generated in the inner part of the alloy container 12! The maximum value of 5P (1) becomes significantly smaller as shown in Figure 3, and the stress is averaged in the thickness direction of the vessel wall, and the stress is dispersed within the vessel wall, increasing the durability of the laminated pressure vessel 11. Not only the performance has been greatly improved, but also the fatigue resistance has been greatly improved.

Furthermore, the weight of the laminated pipe according to the present invention has been significantly reduced, and the withstand pressure per unit wall thickness of the laminated pipe has been significantly improved. Therefore, the weight/pressure and price/pressure ratios could be significantly reduced.

Next, three types of laminated pressure vessel test specimens 1 to 3 (Example,
Comparative Examples 1 and 2) were prepared and the effects of the present invention were confirmed, so they will be explained.

The test specimen 1 is the same as the embodiment shown in FIG. 1.2 described above. Test specimen 2.3 is the same as test specimen 1 in which both the inner and outer container-like layers of the laminated pressure vessel are made of aluminum alloy members and carbon fibers. That is, in test specimen 2, the elastic modulus of both the inner and outer container-like layers of the laminated pressure vessel is 7.200 kgf/
mad”, and in test specimen 3, both were 13.0
00kg f/mm”.

For these specimens, an internal pressure of 1.0 was applied to the cavity inside the specimen.
The distribution of stress S in the circumferential direction generated in each container-like layer when a high-pressure fluid of 0.00 kg f /J was housed was compared.

The results are shown in Figure 3. Test specimen 1 (Example) was compared with Test specimen 2.3 (Comparative example 1.2, respectively), and the stress peak SP inside the specimen.

The stress was significantly reduced, and the stress was dispersed and averaged compared to test specimen 2.3.

In addition, the radial displacement of each part of the test specimen at this time was measured by the fourth
As shown in the figure. The difference in radial displacement is extremely small between the test specimens, and the difference due to the change in the elastic modulus of the tubular layer is small, and there is no practical difference.

In the above-mentioned embodiments, the reinforcing layer is constructed by making the linear members closely adhere to each other in the circumferential direction and laminated in layers in the radial direction, and the linear members alternately intersect between each layer. In the present invention, the reinforcing layer is not limited to this embodiment, but may be one in which linear members are braided so that each layer alternately intersects at a predetermined angle, and the braided layers are laminated in a layered manner. good.

(Effects) As explained above, according to the present invention, the pressure vessel is a laminated pressure vessel in which a plurality of vessel-like layers are laminated, and the stress generated in the tube wall is reduced by specifying the apparent elastic modulus of the vessel-like layer. By uniformly distributing it in the radial direction, it is possible to increase the utilization efficiency of the members of the container wall and significantly increase the pressure resistance performance of the container. Also,
Increases in weight and price of the laminated pressure vessel can be reduced, and the weight/pressure and price/pressure ratios can be significantly reduced.

[Brief explanation of the drawing]

Fig. 1.2 is a view showing an embodiment of the laminated pressure vessel according to the present invention, Fig. 1 is a partial vertical sectional view thereof, and Fig.
It is a sectional view taken along the line ■-■ in the figure. 3.4 is a graph showing the effect of the present invention, FIG. 3 is a graph showing the stress in the circumferential direction, and FIG. 4 is a graph showing the radial displacement. 11... Laminated pressure vessel, 12... Alloy container (container-like layer), 13...
... Reinforcement layer (container-like layer), 16 ... Coating member, 17 ... Cavity, 18 ... Carbon fiber (linear member), El
! l E I 3... Apparent modulus of elasticity.

Claims (1)

[Claims] In a laminated pressure vessel in which a plurality of container-like layers are stacked to form a cavity in which a fluid whose pressure is more positive than the external pressure of the container or a fluid whose pressure is negative than the external pressure of the container is stored, at least one container-like layer is formed in a spiral shape. When the fluid pressure of the fluid acts on the laminated pressure vessel, the apparent elastic modulus of the container-like layer on the high-pressure side is made smaller than the apparent elastic modulus of the container-like layer on the low-pressure side. A laminated pressure vessel featuring: