FR2831235A1 - Shock absorber and vibration damper comprises block of open-cell foam with cavities containing second deformable material such as resin - Google Patents

Abstract

Shock absorber and vibration damper (1) consists of a deformable structure (2) of a first material (3) such as a plastomer or elastomer foam with open cavities (4). The cavities contain a second material (5) such as an injected resin that is able to deform elastically under mechanical shock or pressure. Shock absorber and vibration damper (1) consists of a deformable structure (2) of a first material (3) such as a plastomer or elastomer foam with open cavities (4). The cavities contain a second material (5) such as an injected resin that is able to deform elastically under mechanical shock or pressure. The structure can be enclosed in an envelope or have a covering layer of a woven material to give it extra strength and prevent contact with other materials.

Description

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 The present invention relates to a protection device for damping shocks and / or mechanical vibrations.

 However, although more particularly intended for such applications, said protective device may also be used, especially as thermal and / or electrical insulation.

 A large number of devices are known to protect objects of pressure and / or mechanical shocks. Among these, we know in particular foams that allow the absorption of mechanical shocks and / or vibrations.

 These foam devices, however, have different disadvantages; in particular the damping capacity of these foams is relatively low per unit volume. As a result, these devices are not well adapted to the protection of objects against major mechanical shocks; indeed, their use would require the provision of a large volume around the object to be protected and would make handling very difficult.

 Another type of damping device is also known, it being generally composed of an envelope in which a gel is provided, said envelope and said gel having certain properties such that their interaction provides said damping effect. This type of damping device is adapted to the protection of objects against major mechanical shocks. However, these devices have different disadvantages, and in particular they require the use of a large volume of gel and are of a high price.

 In addition, it can occur, during shocks, ruptures in the envelope that make the device ineffective. Finally, these devices can not have a relatively complex shape, unlike foam damping devices that can be adjusted, including cutting, forms the object to be protected.

 The object of the invention is to provide a protection device that overcomes the aforementioned drawbacks and allows the protection of objects against

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 major mechanical shocks and / or vibrations, while keeping a relatively small volume.

 Another object of the present invention is to provide a protection device whose dimensions can be easily adapted to the shapes of the object to be protected.

 Another object of the present invention is to provide a protection device comprising a deformable structure that does not necessarily require additional envelope.

 Other objects and advantages of the present invention will become apparent from the description which follows, which is given for information only, and which is not intended to limit it.

 According to the invention, the protection device, intended for the damping of shocks and / or mechanical vibrations, comprising a deformable structure, characterized in that said deformable structure comprises: a first foam-type material and having open cavities, a second material, disposed essentially at the level of said open cavities and cooperating with said first material, so as to deform elastically in the open cavities during a mechanical shock and / or a pressure exerted on said deformable structure allowing its damping; .

 The present invention will be better understood on reading the following description, accompanied by the appended drawings, in which: FIG. 1 represents in perspective an embodiment of the protection device according to the invention, FIG. front view of a detail noted 1 of Figure 1, - Figure 3 shows a view similar to Figure 1 in which the device is subjected to mechanical shock,

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 - Figure 4 illustrates a front view of a second embodiment of the device according to the invention, - Figure 5 illustrates a front view of a third embodiment of the device according to the invention.

 The present invention relates to a protection device for damping shocks and / or mechanical vibrations. However, although more particularly intended for such applications, said device may also be used for other applications, and especially as thermal insulation and / or electrical.

 As shown more particularly in FIGS. 1 to 3, said protection device 1 according to the invention comprises a deformable structure 2. Said deformable structure 2 comprises a first material 3 of foam type and having open cavities 4, and a second material 5 disposed substantially at said openings 4.

 Said second material 5 cooperates with said first material 3 so as to elastically deform in said open cavities 5 during a mechanical shock and / or pressure exerted on said structure 2 allowing its damping.

 In an advantageous embodiment, said second material 5 is a resin. Indeed, it has been found after many tests that it was necessary to use a material having high impact resistance properties with a wettable effect allowing said second material to be disposed, in particular by impregnation at said open cavities 4.

il est apparu que certaines résines étaient particulièrement bien adaptées. Des caractéristiques d'une de ces résines sont données dans le tableau ci-après.

- --------------- Among the materials meeting the above characteristics,

it appeared that some resins were particularly well suited. Characteristics of one of these resins are given in the table below.

- ---------------

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<Tb>
<tb> Density <SEP> to <SEP> 230C <SEP> NFT30202 <SEP> 1.05 <SEP> +/- 0. <SEP> 05 / cm3
<tb> Viscosity <SEP> to <SEP> 23 CNFT76102800 <SEP> +/- 200 <SEP> cps
<tb> Viscosity <SEP> to <SEP> 600C <SEP> NFT760102 <SEP> 60 <SEP> +/- 10 <SEP> cps
<tb> Conductivity <SEP> thermal <SEP> W = 0. <SEP> 11 <SEP> w <SEP> m / Kelvin
<tb> Conductivity <SEP> Electrical <SEP> Sup <SEP> 109 <SEP> Ohms
<tb> Expansion <SEP> Coefficient <SEP> 5.3 <SEP> X <SEP> 10-4
<tb>(<SEP> mechanical <SEP> measurement of <SEP> la
<tb> variation <SEP> of <SEP> volume <SEP> vs <SEP> la
<tb> temperature)
<tb> Hardness <SEP> Shore <SEP> to <SEP> 28 <SEP> days <SEP> NFIS0868 <SEP> 5A
<Tb>

According to the invention, said second material 5 is injected into said first material 3. For this purpose, said first foam material 3 comprises open cells 4, preferably said first material 3 is made of a plastomer or elastomer foam and advantageously is of the polyurethane, silicone or neoprene type.

 It is interesting to note that when said second material 5 is carefully disposed at said cavities 4, it does not migrate out of the cavities even when said deformable structure 2 is shocked and / or mechanically vibrated. Thus, said deformable structure 2 thus produced does not require an additional envelope and can be used as such as a protection device 1.

 That being so, according to other embodiments and with reference to FIG. 5, said deformable structure 2 may further comprise an envelope 6. This envelope makes it possible to increase the mechanical strength of said structure 2 and also to prevent the contact between firstly said first and second materials 3 and 5 and secondly the object to be protected.

 This envelope 6 is chosen from materials having elastic properties. These include elastomers or plastomers and advantageously PVC, polyurethane or silicone sheets. AT

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 At this level, it is interesting to note that there is no need to use a waterproof envelope, nor to adapt the envelope perfectly to the content.

 According to another embodiment, and referring more particularly to Figure 4, said deformable structure 2 may further comprise a web 5. The use of this web is preferably in cases where the device protection will have to undergo very significant external constraints. One can, for example, consider its use in the case where the protective device is intended to support heavy loads and for example constructions in seismic zones.

 In the case of using a deformable structure 2 comprising said coated fabric 5, it may provide a particular superimposed assembly of these webs.

 Indeed, given a crushing rate that can exceed 50% of the deformable structure 2, a simple winding of the webs would cause high stress elongations in the fibers of the fabric 5, which could cause breaks and decrease the resistance of said protection device 1.

 To avoid these breaks, it is possible to provide an assembly in which the superposed sheets of said coated fabric are crisscrossed at a given angle so that pressure or impact on said deformable structure 2 causes deformation of the stitches of said coated fabric and not an elongation stress at the level of the fibers of the fabric.

 According to an improvement of this variant using a coated fabric, the fabric may be after assembly coated including a plastomer or an elastomer.

 According to another variant of the invention, not shown in the accompanying drawings, it is also conceivable to combine in particular the envelope 6 and the coated fabric 5. In this variant, said deformable structure 2 therefore comprises at least said first material 3 and said second material 5, the assembly formed by said first and second materials 3 and 5 being covered by the envelope 6, the latter covered with said coated fabric

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 5.

 This envelope 6 disposed between the assembly formed by said first and second materials 3 and 5, and said coated fabric 7 in particular to facilitate the assembly sheet.

 That being so, the protective device 1 operates in the following manner: when an impact and / or a pressure is exerted on said deformable structure 2, said open cavities 4 deform and cause a crushing of said first material 3 at the level of cavities 4, the deformation causes the displacement of said second material 5 whose creep varies with the pressure.

 It has been observed that the cooperation between said first material 3 and said second material 5 makes it possible to obtain a damping effect that is much greater than that of the first material 3 used alone.

 Referring to FIG. 3, it can be seen that the protective device 1 is subjected to an external pressure which causes deformation of said deformable structure 2. It can thus be seen that the structure 2 collapses perpendicular to the pressure exerted and that the flanks round. Structure 2 however returns to its original form as soon as the external pressure stops.

 It is important to note that, given the substantially spherical shape of said cavities 4, said structure 2 can deform in all directions and thus allow good damping of the pressures exerted on said structure 2 regardless of the direction of these pressures.

 Referring to FIG. 5, it can be seen that said deformable structure 2 is placed at a rigid element 8. In this example, an outline 9 of the deformable structure 2 is driven into said rigid element whose internal peripheral dimensions are close to those of contour 9 of structure 2.

 Said rigid element makes it possible to limit the deformations in the plane perpendicular to the contour 9 during an impact or a pressure, said

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 rigid element 8, preferably constituted by a cylindrical tube, is mounted floating, that is to say that said rigid element 8 moves according to the movements of said structure 2.

 The operation of the protection device 1 comprising a deformable structure 2 associated with the rigid element 8 is as follows: a pressure is exerted perpendicular to the plane containing the contour 9, this pressure causes a collapse of said structure 2. This crushing is contained by the internal walls of the rigid element 8, the latter being in fact indeformable does not allow deformation of the contour 9 greater than the internal dimensions of said element 8.

 This variant using said rigid element 8 allows the use of the protection device 1 for higher loads than in the absence of this rigid element 8, the counterpart is that the damping of shocks or pressures is reduced.

 As indicated above, the protection device 1 is intended for the damping of mechanical shocks. However, during the various tests carried out, it has been found that said protective device 1 also constituted an excellent thermal insulator.

 Thus, it has been possible to obtain using the resin whose characteristics are set out in the previous table, a protection device whose thermal conductivity is close to 0.11 to 0.12 wm / Kelvin.

Similarly, tests have shown that said protection device 1 also constituted an excellent electrical insulator, it could thus be obtained by using the resin whose characteristics are shown in the table above a protection device whose resistance is greater than
109 ohms.

 It is therefore quite possible to use the protective device 1 as thermal or electrical insulation.

 For this purpose, in the same way as when it is intended for the damping of mechanical shocks, this protection device can be presented in any type of form and in particular in the form of panels. Of

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 moreover, given the nature of the deformable structure 2, it is easy to adapt the dimensions of said device 1 to the object to be protected.

 Naturally, other embodiments, within the reach of those skilled in the art, could have been envisaged without departing from the scope of the invention defined by the claims below.

Claims (12)

1. Protection device (1), intended for damping shocks and / or mechanical vibrations, comprising a deformable structure (2), characterized in that said deformable structure (2) comprises: a first material (3) of type foam and having open cavities (4), - a second material (5) disposed substantially at said open cavities (4) and cooperating with said first material (3), so as to deform elastically in said open cavities ( 4) during a mechanical shock and / or pressure exerted on said structure (2) allowing its damping.  2. Protective device according to claim 1, wherein said second material (5) is a resin.  3. Protective device according to claims 1 or 2, wherein said second material (5) is injected into said first material (3).  4. Protection device according to any one of the preceding claims, wherein said first material (3) is a plastomer or elastomer type foam.  5. Protection device according to any one of the preceding claims, wherein said deformable structure (2) further comprises an envelope (6) for increasing the mechanical strength of said deformable structure (2) and preventing contact between said first and second materials (3 and 5) with the object to be protected.  6. Protective device according to any one of claims 1 to 4 above, wherein said deformable structure (2) comprises a cloth web (7) for increasing the resistance of the protective device to the pressure.  7. Protective device according to claim 6, wherein the plies of said coated fabric (7) are intersecting at a given angle so that pressure and / or mechanical shock on said deformable structure (2) generates a warp deformation and not a <Desc / Clms Page number 10>  stress of elongation at the level of the fibers of the fabric.  8. Protection device according to claims 6 or 7 above, wherein said coated fabric (7) is coated.  9. Protection device according to any one of claims 6 to 8 above, wherein said deformable structure (2) further comprises an envelope (6) disposed between the assembly formed by said first and second materials (3 and 5) and said coated fabric (7).  10. Protection device according to any one of the preceding claims, wherein a contour (9) of said deformable structure (2) is enchased in a rigid element (8) whose inner peripheral dimensions are close to those of the contour (9). ) of said deformable structure (2) so as to limit the deformations in the plane perpendicular to the contour (9) during a mechanical shock and / or pressure.  11. Application of the protection device according to any one of the preceding claims, as thermal insulation.  12. Use of the protection device according to any one of the preceding claims, as electrical insulation.