FR2657407A2 - Composite flexible separator for a pressure vessel, method for producing it, and pressure vessel including such a flexible separator - Google Patents

Abstract

This is a flexible separator of the sort including, according to Claim 1 of the main patent, three adjacent layers of deformable material, namely an outer layer (21A), an inner layer (21B), and an intermediate layer (23) which, at least partially impermeable to gases, includes a metallic sheet (24). According to the invention, the metallic sheet (24) being at least partly broken down into sheet elements (32), these sheet elements (32) at least adjoin one another for the rest configuration of the flexible separator (12). Application, especially, to composite flexible separators for pressure vessels.

Description

"Flexible composite separator for pressure tank,
its production process, and pressure tank
having such a flexible separator "
The main patent has described a flexible composite separator for a pressure tank comprising three adjacent layers of deformable material, namely an outer layer, an inner layer, and an intermediate layer which, to be at least partially impermeable to gases, comprises a metal sheet.

 These various layers being manufactured in isolation, then successively nested with each other, the problem, in this case, is, starting from an initially flat blank, to conform the metal sheet to the configuration of the inner and outer layers which must l 'frame.

 In the main patent, it is proposed to do this by forming, and, more precisely, by hydroforming.

 It turns out, from experience, that such a formation results in the creation, within the metal, of internal constraints which, coming to weaken this metal, are likely, in service, to be subsequently origin of cracks developing in an uncontrolled manner and detrimental to the desired seal.

 The present invention generally relates to a provision such as to avoid the formation of such cracks.

 More specifically, it firstly relates to a flexible composite separator for a pressure reservoir, of the type comprising, according to claim 1 of the main patent, three adjacent layers of deformable material, namely an outer layer, an inner layer , and an intermediate layer which, at least partly impermeable to gases, comprises a metal sheet, this flexible separator being generally characterized in that, said metal sheet being at least partly divided into sheet elements, said elements sheets are at least contiguous with each other for the rest configuration of the separator.

 It also relates to any pressure tank comprising such a flexible separator.

 Finally, it relates to a process for producing this flexible separator, according to which, in accordance with claim 13 of the main patent, each of the layers constituting it is manufactured in isolation and they are successively fitted together, this process being '' generally characterized in that, for the manufacture of the intermediate layer, one starts from an initially flat blank, which comprises the metal sheet to be used, or which is reduced to such a sheet, and is cut flat this blank so as to individualize the sought-after sheet elements therein, so that, these sheet elements being spaced apart from one another over at least part of their contour, they are able, by this contour, to become at least contiguous with each other when the intermediate layer thus formed is placed between the inner and outer layers which must frame it.

 According to a first possible embodiment of the invention, these sheet elements are joined with each other, by their edges, for the rest configuration of the separator.

 In this case, the decision is systematically taken to possibly accept a certain, limited, sealing gap between the sheet elements used, if these deviate slightly from each other when the flexible separator s' deviates from its rest configuration.

 In fact, the time during which the flexible separator is in the rest configuration or in a configuration close to the latter is in practice very largely predominant.

 In addition, the calculation shows, and experience confirms, that, taken as a whole, the rate of impermeability to gases then remains very important anyway, being much greater than 90%, or even 95%.

 Nais, according to a second preferred embodiment of the invention, the sheet elements used overlap successively at least in part with each other along their lateral sides.

 The gas impermeability rate is then even higher.

 In all cases, the sheet elements used individually having only a limited extension, the shaping, itself limited, of which they are the object after they are cut flat, even during assembly. and pressing the three layers concerned, is advantageously not such as to generate internal stresses which may then be the source of any cracks.

 Thus, with a flexible separator produced in accordance with the invention, such cracks are not observed in service in the sheet elements constituting the metal sheet which it comprises, and, consequently, the rate of gas leakage from this flexible separator advantageously remains stable over time.

 Finally, the arrangement according to the invention is favorable to an industrialization of the manufacturing process of the flexible separator concerned, by facilitating the shaping of the metal sheet of its intermediate layer, in particular when, according to a preferred embodiment, the elements of sheet cut from this metal sheet remain attached to each other.

 Admittedly, it has already been proposed, by the Japanese utility model published under No. 63-190902, to ensure that there is ensured fractionation into sheet elements of a metal sheet used to control the impermeability to gas from a flexible separator.

 But, in addition to the fact that in this Japanese utility model, the metal sheet is arranged on the surface of this flexible separator, its splitting into sheet elements does not take place until after it has been placed thereon, resulting in lines of least resistance affecting it for this purpose.

 It therefore does not resolve the question of the formatting, with the configuration of the flexible separator to be fitted, of an initially flat sheet, and, moreover, nothing ensures that the desired fractionation takes place exactly according to the expected modalities, risk, again, of the development of internal stresses likely then to generate cracks.

 It is not the same, with the arrangement according to the invention, thanks to the fact that the metal foil used is, systematically, and therefore in a perfectly controlled manner, divided, from the outset, flat, into elements of sheet.

 In addition, there is every reason to believe that, in service, the gas leakage rate of the flexible separator described in the Japanese utility model is, by reason of the fractionation practiced, very important.

 Indeed, having regard to the fact that this fractionation takes place in situ, on the very surface of the flexible separator, the sheet elements which result therefrom can at best only be joined.

 It is not the same with the arrangement according to the invention, according to which, if desired, these sheet elements can on the contrary overlap each other successively.

The characteristics and advantages of the invention will emerge from the description which follows, by way of example, with reference to the appended schematic drawings in which
Figure 1 is, with a local cutaway, an axial sectional view of a flexible separator according to the invention
Figure 2 shows, on a larger scale, the detail of Figure 1 identified by an insert II in this Figure 1
Figure 3 is a view, flat, of the metal sheet used, according to the invention, for the constitution of the intermediate layer that comprises this flexible separator
Figure 4 is an exploded axial sectional view, which, similar to that of Figure 1, represents, individually, this intermediate layer and the inner and outer layers which surround it
Figure 5 is an axial sectional view, which, partly taking that of Figure 4, relates to the single metal sheet, according to an alternative embodiment of the invention;
Figure 6 is a plan view of this metal sheet, according to arrow VI of Figure 5
FIG. 7 is, on a larger scale, a cross-sectional view along the line VII-VII of FIG. 5.

 These figures show a flexible composite separator 12 of the type described in the main patent.

 For convenience, the same references as in this one have been used.

 Only the elements of this flexible separator 12 necessary for understanding the invention will be described here.

 In practice, in the embodiments shown, this flexible separator 12 is of the type whose deformation in service is done by unwinding, and not by extension.

 As in the main patent, this flexible separator 12 has three adjacent layers, namely, an outer layer 21A, which is made of deformable material, and, for example, made of elastomer, an inner layer 21B, which is also made, for example, of elastomer , and an intermediate layer 23, which, at least partially impermeable to gases, comprises a metal sheet 24, for example an aluminum sheet.

 In the embodiments shown, the intermediate layer 23 is reduced to this metal sheet 24.

 According to the invention, this metal sheet 24 is at least partially divided into sheet elements 32, and these sheet elements 32 are at least contiguous with each other for the rest configuration of the flexible separator 12, as shown in Figure 1.

 In the embodiment more particularly shown in FIGS. 1 to 4, the sheet elements 32 are exactly contiguous with each other, by their edges, for the rest configuration of the flexible separator 12, and, all identical between them, they are radiating from the base of this flexible separator 12, where, as indicated in the main patent, the latter usually carries a button 20.

 To manufacture the intermediate layer 23 thus formed, one starts from an initially flat blank 23 ′, and, as illustrated in FIG. 3, it is cut flat so as to individualize the desired sheet elements 32 therein.

 In the embodiments shown, these sheet elements 32 generally have a triangular contour, with, radiating from a central zone corresponding to the base of the flexible separator 12, lateral sides 34, which, to be joined later , are convex, and, opposite this base, a substantially rectilinear side 35.

 In practice, in the embodiment more particularly shown in FIGS. 1 to 4, the central zone from which the sheet elements 32 thus radiate is materialized by a central patch 33, which is common to all these elements sheet 32, and which corresponds to the base of the flexible separator 12, and, all in one piece with this central pad 33, these sheet elements 32 remain adjoining, and therefore integral, with each other.

 Due to the convex outline of their lateral sides 34, the sheet elements 32 are spaced apart from one another on the part of their outline corresponding both to these convex lateral sides 34 and to their substantially straight sides 35.

 But, in the embodiment shown in Figures 1 to 4, their cutting is made so that, by this outline, they are able to become exactly joined with each other, by their edges, when, as shown in FIG. 4, the intermediate layer 23 formed from the metal sheet 24 thus divided into sheet elements 32 is placed between the inner layers 21B and the outer layers 21A.

 For this positioning configuration, the sheet elements 32 are therefore edge to edge with one another by their convex lateral sides 34, while their substantially rectilinear sides 35 are continuously with each other, along a corresponding circumference. generally at the periphery of the flexible separator 12.

 In practice, the number of sheet elements 32 used is at least six.

 In the embodiment shown in Figures 1 to 4, this number is equal to eight.

 The sheet elements 32 therefore have individually only a reduced extension, so that their shaping according to the general configuration to be obtained for the flexible separator 12 does not induce any significant internal stress.

 For the rest, it is carried out as described in the main patent.

 In short, once produced in isolation, the layers 21B, 23, 21A constituting the flexible separator 12 to be obtained are nested successively with each other, either from the inside, from the external layer 21A, as shown in the figure 4, or from the outside, from the internal layer 21B, and their mutual bonding is carried out jointly in press.

 It is only during the corresponding pressing that the intermediate layer 23 conforms to the reliefs provided on the external layer 21A and on the internal layer 21B for the adaptation of the assembly to the shape of the button 20 otherwise used.

 In the embodiment illustrated in FIGS. 5 to 7, it is arranged so that, for the rest configuration of the flexible separator 12 concerned, the sheet elements 32 of the metal sheet 24 constituting the intermediate layer 23 successively overlap at least in part with each other along their lateral sides 34.

 In the embodiment shown, these sheet elements 32 are twelve in number.

 As an indication, the recovery rate of one of them by another is for example of the order of 10%.

 For the rest, the provisions are of the same type as those described above.

 Of course, the present invention is not limited to the embodiments described and shown, but encompasses any variant, in particular as regards the number and / or the shape of the sheet elements used, which, moreover, are not necessarily identical between them.

 In addition, instead of being adjoining, and therefore integral, via a pellet, these sheet elements can be separate.

 Finally, if, in the above, the intermediate layer of the flexible separator according to the invention is reduced to a metal sheet, it can just as easily be formed, for example, as indicated in the main patent, of a composite sheet in which such a metallic sheet is sandwiched between two protective sheets of synthetic material, by adhering to these.

 In such a case, obviously, the blank in which a cut into sheet elements must be made is the blank formed by all of these sheets.

Claims (12)

 1. Flexible composite separator for a pressure tank, of the type comprising, according to claim 1 of the main patent, three adjacent layers of deformable material, namely an outer layer (21A), an inner layer (21B), and an intermediate layer ( 23) which, at least partly impermeable to gases, comprises a metal sheet (24), characterized in that, said metal sheet (24) being at least partially divided into sheet elements (32), said sheet elements ( 32) are at least contiguous with each other for the rest configuration of the separator.  2. Flexible separator according to claim 1, characterized in that, for the rest configuration of the separator, said sheet elements (32) successively overlap at least in part with each other along their lateral sides.  3. Flexible separator according to any one of claims 1, 2, characterized in that said sheet elements (32), all identical to each other, are radiating from the base of the separator.  4. Flexible separator according to claim 3, characterized in that said sheet elements (32) have a generally triangular outline, with, radiating from the base of the separator, lateral sides (34) convex, and, at the opposite of said base, a substantially straight side (35).  5. Flexible separator according to any one of claims 3, 4, characterized in that the number of said sheet elements (32) is at least six.  6. Flexible separator according to claim 5, characterized in that the number of said sheet elements (32) is at least equal to eight.  7. Flexible separator according to any one of claims 3 to 6, characterized in that all the sheet elements (32) are in one piece with a central pad (33), which is common to them, and which corresponds to the base of the separator.  8. Flexible separator according to any one of claims 1 to 7, characterized in that the intermediate layer (23) is reduced to a metal sheet (24).  9. Flexible separator according to any one of claims 1 to 7, characterized in that the metal sheet (24) of the intermediate layer (23) is taken between two protective sheets of synthetic material, adhering thereto.  10. Flexible separator according to any one of claims 1 to 9, characterized in that the metal sheet (24) is an aluminum sheet.  11. Method for producing a flexible separator according to any one of claims 1 to 10, according to which, in accordance with claim 13 of the main patent, each of the layers (21A, 21B, 23) constituting this is produced in isolation flexible separator and they are successively fitted together, characterized in that, for the manufacture of the intermediate layer (23), one starts from an initially flat blank, and this blank is cut flat so as to individualize it sheet elements (32), which, separated from one another over at least part of their contour, are capable, by this contour, of becoming at least contiguous with each other when the intermediate layer (23) thus formed is placed between the inner (21B) and outer (21A) layers.  12. Pressure tank of the kind comprising a flexible separator according to claim 15 of the main patent, characterized in that said flexible separator conforms to any one of claims 1 to 10.