EP0344025B1 - Storage tank for a fluid under pressure - Google Patents

Description

The present invention relates to a container for the storage of pressurized fluid.

More particularly, although not exclusively, the invention relates to so-called "bottle" containers for storing gases, such as air, oxygen, nitrogen, carbon dioxide, used in different industrial sectors .

We already know, for example from document US-A-3 508 677, such a container for the storage of gas under pressure, generally comprising an inner casing having a central cylindrical part and two curved end parts. , and a hooping of resistant fibers coated with a curable binder, surrounding said envelope.

In this case, the envelope is of constant thickness, both in the cylindrical central part and in the two curved end parts.

However, such a constant thickness, taking into account the differences in stresses between the central part and the end parts, implies that, in order to obtain good resistance of the container, the central part must have an excess thickness compared to what would be necessary. This results in an "overweight" of the container, which is particularly disadvantageous when such containers are intended to be used in spacecraft, or to be transported on the back of a man (diving tanks, for example).

Furthermore, document GB-A-1 072 420 describes a container, in particular intended to form the envelope of a rocket engine, comprising an inner envelope of revolution form around a longitudinal axis XX ′, having a cylindrical central part and two end parts, at least one of said end parts being curved outwards and having an external contour which has, in longitudinal section, an at least approximately elliptical shape, a hoop of resistant fibers coated with 'a curable binder surrounding said envelope and having at least one planetary winding leaving free, at said curved end portion, a cap centered on said axis X, X ′.

It will be noted that, in this last container, the evolution of said contour is particularly complex since it involves elliptical functions, that is to say in reality functions containing polynomials. It will also be noted that the ratio of the half minor axis to the major axis of the ellipse is equal to 0.3. Finally, it will be noted that the production of the inner envelope does not make it possible to deduce, for the curved ends, any change in thickness.

The present invention relates to a container for the storage of pressurized fluid, of the type described for another use by document GB-A-1 072 420 and making it possible to avoid the drawback mentioned above with regard to the container of the document US-A-3 508 677. It relates to a pressurized fluid storage container adapted to present the best possible weight / resistance ratio.

où le grand axe correspond au diamètre extérieur de la partie centrale cylindrique (2a) de l'enveloppe (2), et en ce que l'épaisseur ei de ladite partie d'extémité bombée (2b) de l'enveloppe (2), ladite calotte (6) étant exclue, varie suivant la formule : $${\text{e}}_{\text{i}}\text{=}\frac{\text{e₁ - e}}{\text{R - R₁}}{\text{(R - R}}_{\text{i}}\text{) + e}$$

dans laquelle :

R_i =

distance à l'axe X,X′ du point du contour extérieur (8) de ladite partie d'extrémité bombée (2b), auquel est mesurée l'épaisseur e_i,

e =

épaisseur de l'enveloppe (2) dans la partie centrale cylindrique (2a) de celle-ci,

R =

rayon extérieur de la partie centrale cylindrique de l'enveloppe,

R₁ =

rayon de la base de ladite calotte, et

e₁ =

épaisseur de l'enveloppe pour R_i = R₁,

l'épaisseur de ladite calotte étant au moins égale à e₁.To this end, according to the invention, the container of the type mentioned above and intended for the storage of pressurized fluid is characterized in that said at least approximately elliptical external contour (8) of said convex end portion (2b) of the envelope (2) is such that the ratio G of the half minor axis to the major axis is such that: $$\text{0.32 ≦ G ≦ 0.40}$$

where the major axis corresponds to the outside diameter of the cylindrical central part (2a) of the casing (2), and in that the thickness ei of said curved end part (2b) of the casing (2), said cap (6) being excluded, varies according to the formula: $${\text{e}}_{\text{i}}\text{=}\frac{\text{e₁ - e}}{\text{R - R₁}}{\text{(R - R}}_{\text{i}}\text{) + e}$$

in which :

R _i =

distance to the axis X, X ′ from the point of the external contour (8) of said convex end portion (2b), at which the thickness e _i is measured,

e =

thickness of the envelope (2) in the cylindrical central part (2a) thereof,

R =

outer radius of the cylindrical central part of the envelope,

R₁ =

radius of the base of said cap, and

e₁ =

thickness of the envelope for R _i = R₁,

the thickness of said cap being at least equal to e₁.

Thus, the container according to the invention has the best possible weight / resistance ratio, since it does not include any additional thickness in the central cylindrical part of the envelope. Furthermore, the elliptical shape of the curved end portions makes it possible to obtain a greater volume, for example compared to a hemispherical shape, for the same length, that is to say the same size, of the container. In addition, this elliptical shape provides better seating for the planetary winding.

In particular, said ratio G is such that: $$\text{0.34 ≦ G ≦ 0.35.}$$

Advantageously, the inner contour of said curved end portion of the envelope has, in longitudinal section, an at least approximately elliptical shape.

According to another characteristic of the invention, the two end parts of the envelope are curved outwards, at least one of said parts being provided with a filling orifice.

According to yet another characteristic of the invention, an end portion of the envelope has a neck, and, at least at the periphery of said end portion, the outer contour of the latter has, in longitudinal section, a at least approximately elliptical shape according to formula (I) and, at least at said periphery, the thickness of said end portion varies according to formula (II).

Advantageously, at least at the periphery of said end portion having the neck, the internal contour of the latter has, in longitudinal section, an at least approximately elliptical shape.

In the case where the container has a neck, suitably, said hooping rests on said neck.

According to another characteristic of the invention, said hooping comprises at least one circumferential winding on said planetary winding, in correspondence with at least the cylindrical central part of the envelope.

In particular, said hooping consists of an alternation of planetary windings and circumferential windings.

Furthermore, said envelope can be made of metal, for example aluminum.

The figures of the appended drawing will make it clear how the invention can be implemented. In these figures, identical references designate similar elements.

Figure 1 is a longitudinal sectional view of a container according to the invention.

FIG. 2 shows, on an enlarged scale, a curved end portion of the container of FIG. 1.

Figure 3 is a view similar to Figure 2 showing an alternation of planetary windings and circumferential windings.

Figure 4 is a view similar to Figure 1 of a container, according to the invention, having a neck.

Referring more particularly to FIG. 1, the container 1 for the storage of pressurized fluid comprises an inner casing 2, for example made of aluminum, of shape of revolution around a longitudinal axis X, X ′, having a central part cylindrical 2a and two end portions 2b curved outwards. One of the end parts 2b, on the right in FIG. 1, has an orifice 3 for filling the container with a fluid. Furthermore, the container 1 has a hooping 4 of resistant fibers (for example glass, Kevlar (registered trademark), carbon, boron) coated with a curable binder, surrounding the envelope 2. For clarity of the drawing, the hooping 4 shown in Figures 1 and 2 comprises a single planetary winding 5, leaving open, at the end portions 2b, a cap 6 centered on the axis X, X ′.

However, advantageously, as shown in FIG. 3, the hooping 4 generally consists of an alternation of planetary windings 5 and circumferential windings 7. Each of the latter applies to the planetary winding 5 immediately below , in correspondence with the cylindrical central part 2a of the envelope 2.

où le grand axe correspond au diamètre extérieur de la partie centrale cylindrique 2a de l'enveloppe 2, et l'épaisseur e_i de chaque partie d'extrémité bombée 2b de l'enveloppe 2, ladite calotte 6 étant exclue, varie suivant la formule : $${\text{e}}_{\text{i}}\text{=}\frac{\text{e₁ - e}}{\text{R - R₁}}{\text{(R - R}}_{\text{i}}\text{) + e}$$

dans laquelle :

R_i =

distance à l'axe X,X′ du point du contour extérieur 8 de ladite partie d'extrémité bombée 2b, auquel est mesurée l'épaisseur e_i,

e =

épaisseur de l'enveloppe 2 dans la partie centrale cylindrique 2a de celle-ci,

R =

rayon extérieur de la partie centrale cylindrique 2a de l'enveloppe 2,

₁ =

rayon de la base de ladite calotte 6, et

e₁ =

épaisseur de l'enveloppe 2 pour R_i = R₁, l'épaisseur de ladite calotte 6 étant au moins égale à e₁.

As already indicated, and with more particular reference to FIG. 2, according to the invention, the external contour of the curved end portions 2b of the envelope 2 has, in longitudinal section, an at least approximately elliptical shape such that the ratio G of the half minor axis to the major axis is such that: $$\text{0.32 ≦ G ≦ 0.40}$$

where the major axis corresponds to the external diameter of the cylindrical central part 2a of the casing 2, and the thickness e _i of each convex end part 2b of the casing 2, said cap 6 being excluded, varies according to the formula : $${\text{e}}_{\text{i}}\text{=}\frac{\text{e₁ - e}}{\text{R - R₁}}{\text{(R - R}}_{\text{i}}\text{) + e}$$

in which :

R _i =

distance to the axis X, X ′ of the point of the external contour 8 of said convex end portion 2b, at which the thickness e _i is measured,

e =

thickness of the casing 2 in the cylindrical central part 2a thereof,

R =

outer radius of the cylindrical central part 2a of the casing 2,

₁ =

radius of the base of said cap 6, and

e₁ =

thickness of the envelope 2 for R _i = R₁, the thickness of said cap 6 being at least equal to e₁.

More particularly, said ratio G can be such that: $$\text{0.34 ≦ G ≦ 0.35}$$

Furthermore, the inner contour 9 of each curved end portion 2b of the envelope 2 has, in longitudinal section, an at least approximately elliptical shape.

FIG. 4 illustrates another example of embodiment of a container 1 according to the invention, in which an end portion 2b curved towards the outside has a neck 10, the planetary winding 5 of the hoop 4 resting on the neck 10.

In this case, at the periphery 11 of said end portion 2b, the outer contour 12 of the latter has, in longitudinal section, an at least approximately elliptical shape according to formula (I) and, at least at said periphery 11, the thickness of said end portion 2b varies according to formula (II).

Furthermore, at the periphery 11 of said end portion 2b having the neck 10, the inner contour 13 of the latter has, in longitudinal section, an at least approximately elliptical shape.

• professionnels de la sécurité (pompiers, protection civile, hôpitaux...),
• service de la sécurité des entreprises industrielles, services publics, pétroliers, grandes usines chimiques et armées,
• activités sous-marines, plongées "professionnels et amateurs", sous-marins, mineurs,
• transports, bouteilles embarquées.

As already indicated, the invention applies more particularly to high performance cylinders for storing gases such as air, oxygen, nitrogen, carbon dioxide, intended for the following sectors:

• security professionals (firefighters, civil protection, hospitals ...),
• security service for industrial companies, public services, petroleum companies, large chemical factories and armies,
• underwater activities, "professional and amateur" dives, submarines, miners,
• transport, on-board bottles.

Claims (10)

1. Container for storing fluid under pressure, of the type comprising an inner envelope which is a body of revolution about a longitudinal axis X-X′, having a cylindrical central part and two end parts, at least one of the said end parts being bulged outwards and having an outer contour which has, in longitudinal section, an at least approximately elliptical shape, a reinforcement of resistant fibres coated with a hardenable binder surrounding the said envelope and having at least one planetary winding leaving free, at the said bulged end part, a cap centred on the said axis X, X′,
   characterised in that the said at least approximately elliptical outer contour (8) of the said bulged end part (2b) of the envelope (2) is such that the ratio G of the small semiaxis to the large axis is such that: $$\text{0.32 ≦ G ≦ 0.40}$$

   

   where the large axis corresponds to the external diameter of the cylindrical central part (2a) of the envelope (2), and in that the thickness ei of the said bulged end part (2b) of the envelope (2), excluding the said cap (6), varies in accordance with the formula: $${\text{e}}_{\text{i}}\text{=}\frac{\text{e₁ - e}}{\text{R - R₁}}{\text{(R - R}}_{\text{i}}\text{) + e}$$

   

   in which:

   R_i =   distance to the axis X, X′ of the point on the outer contour (8) of the said bulged end part (2b) at which the thickness ei is measured,

   e =   thickness of the envelope (2) in the cylindrical central part (2a) of the latter,

   R =   outer radius of the cylindrical central part (2a) of the envelope (2),

   R₁ =   radius of the base of the said cap (6), and

   e₁ =   thickness of the envelope (2) for R_i = R₁, the thickness of the said cap (6) being at least equal to e₁.
2. Container according to Claim 1, characterised in that the said ratio G is such that: $$\text{0.34 ≦ G ≦ 0.35.}$$

   
3. Container according to Claim 1 or Claim 2, characterised in that the inner contour (9) of the said bulged end part (2b) of the envelope (2) has, in longitudinal section, an at least approximately elliptical shape.
4. Container according to any one of Claims 1 to 3, characterised in that the two end parts (2b) of the envelope (2) are bulged outwards, at least one of the said parts being provided with a filling orifice (3, 10).
5. Container according to Claim 4,
   characterised in that one end part (2b) of the envelope (2) has a neck (10), and in that, at least at the periphery (11) of the said end part (2b), the outer contour (12) of the latter has, in longitudinal section, an at least approximately elliptical shape in accordance with the formula (I) and, at least at the said periphery (11), the thickness of the said end part (2b) varies in accordance with the formula (II).
6. Container according to Claim 5,
   characterised in that, at least at the periphery (11) of the said end part (2b) having the neck (10), the inner contour (13) of this end part (2b) has, in longitudinal section, an at least approximately elliptical shape.
7. Container according to Claim 5 or Claim 6,
   characterised in that the said reinforcement (4) bears on the said neck (10).
8. Container according to any one of Claims 1 to 7, characterised in that the said reinforcement (4) comprises at least one circumferential winding (7) on top of the said planetary winding (5), corresponding with at least the cylindrical central part (2a) of the envelope (2).
9. Container according to Claim 8,
   characterised in that the said reinforcement (4) consists of alternating planetary windings (5) and circumferential windings (7).
10. Container according to any one of Claims 1 to 9, characterised in that the said envelope (2) is made from metal, for example from aluminium.

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