GB2265208A

GB2265208A - Thermally insulating laminated element

Info

Publication number: GB2265208A
Application number: GB9301656A
Authority: GB
Inventors: Stefan Lahner; Manfred Roller; Max Wagner; Otto Neurieder
Original assignee: M Faist GmbH and Co KG
Current assignee: M Faist GmbH and Co KG
Priority date: 1992-03-19
Filing date: 1993-01-28
Publication date: 1993-09-22
Anticipated expiration: 2013-01-28
Also published as: GB9301656D0; ITRM930029U1; ITRM930029V0; FR2688739A1; DE9203734U1; ES1025093U; IT232160Y1; PT8701U; GB2265208B; PT8701T; FR2688739B3; ES1025093Y

Abstract

A carrier sheet (1) of aluminium is held at a distance from a thin metal sheet (2), also of aluminium, by spacer means (3), also of aluminium. The thickness of the metal sheet (2) is up to 0.5 mm. The spacer means may comprise one or more recesses pressed out of one or both of the sheets themselves, and/or an aluminium fibre mat (Fig 5 not shown), and/or laminate of expanded metal (also aluminium) with or without additional layers of aluminium foil (Fig 4 not shown). <IMAGE>

Description

THERMALLY INSULATING LAMINATED ELEMENT Thermally insulating laminated elements of the type comprising a carrier sheet of aluminium and a thin metal sheet of aluminium which is held at a distance from the carrier by spacer means, also of aluminium, have been previously disclosed, for example in German Patent Specification Nos. DE 38 21 468 A 1 and DE-GM 91 07 484.

Laminated elements of this type are used as a sort of "heatshield" for heat-screening of components or spaces, in particular of objects where a high degree of heat develops, such as in the engine compartment or the exhaust system of a motor vehicle.

The known laminated elements have a lattice structure as the carrier sheet, for example expanded metal or wiring mesh, so that due to the passages therethrough sound-absorption can also be effected by an insulating mat, which serves as spacer means between the lattice structure, i.e. the carrier sheet, on the one side and the thin metal sheet, e.g.

aluminium foil, which can also be a lattice structure, on the other side. Inorganic fibres, in particular of mineral or glass, as well as inorganic or organic foam materials, for example polyurethane, or an aluminium mesh structure of foil thickness, may be used for the insulating mat, which serves as the spacer means.

It is an object of the invention to improve a thermally insulating laminated element of this type by simple means so that it offers, in spite of its easy manufacture, a thermal insulating effect of long term stability, and that its base material can be easily processed for re-use without elaborate separating processes.

According to the invention the spacer means are formed by recesses in the thin metal sheet and/or in the carrier sheet, and/or by a mat of aluminium fibre, and/or by a laminate of aluminium expanded metal.

A thickness of up to 0.5 mm is preferable for the thin metal sheet of aluminium, and the spacer means, in one version, are also formed from the aluminium metal sheet and/or the carrier sheet. It is also possible to use a specific expanded metal of aluminium, in particular a hard AlMgSialloy.

This inventive laminated element is thus made entirely of aluminium. In this respect the term "aluminium" is to be understood to include aluminium alloys.

In addition to the fact that recycling operations do not require complicated procedures for separating aluminium elements from other materials, and that no environmentally damaging products arise upon recycling, it is also an advantage of such an all-aluminium heatshield that no materials of widely differing thermal expansion coefficients are used, which in the past has often resulted in the breaking up of individual layers of such laminates.

In the laminated element of the invention the carrier sheet can advantageously be welded to the thin metal sheet, in which respect spot welding and laser welding are probably most suitable.

It is advantageous, particularly when connection by welding is to be employed, to emboss or compress onto one of the two sheets recesses in the shape of wells or dimples or the like as respective spacers, so that no addtional spacers have to be inserted between the two sheets which are to be laminated. The gap between the thin metal sheet of aluminium and the carrier sheet, which is also of aluminium, can be easily set by the dimension of the depth of these recesses. As regards laminated elements of large surface area which need to have better thermal insulation is specified surface areas than in other surface areas, all that is required is to increase the gap between the sheets in the areas of enhanced insulation.

The term "thin metal sheets" of aluminium is to be understood to include so-called "thin bands" having a laminate thickness of between 0.021 and 0.249 mm.

Occasionally, these thin bands are described differently, for example as "foils", although the laminate thickness of foils is really less, and is usually between 0.004 and 0.020 mm.

The gap can additionally or alternatively be filled by an aluminium fibre mat or by a layer of expanded aluminium made of a very hard AlMgSi alloy. This special aluminium alloy prevents compression of the spacer due to external mechanical effects and during three-dimensional forming.

Exemplary arrangements of the invention will now be explained in more detail, with reference to the accompanying drawings, in which: Fig. 1 is a schematic cross-section through a first embodiment of the invention; Fig. 2 is a schematic cross-section through a second embodiment of the invention; Fig. 3 is a perspective view of a section in the edge region of a third embodiment of the laminated element of the invention; Fig. 4 is a schematic cross-section through a fourth embodiment of the invention; and Fig. 5 is a schematic cross-section through a fifth embodiment of the invention.

As shown in Fig. 1, an aluminium sheet, suitably between 0.2 and 0.5 mm laminate thickness, is used as a carrier sheet 1.

A thin metal sheet 2, which is also of aluminium, is arranged at a distance from this carrier sheet 1. The gap between these two sheets is maintained by recessses 3, which are pressed out of the metal sheet 2 in the illustrated case, but it could be the carrier sheet 1 in other cases, in the shape of wells or dimples. The sheets 1 and 2 can be connected at the points of contact between the recesses 3 and the carrier sheet 1 by way of welding at welding points 4, in particular by spot welding. Alternatively or addtionally other connecting means can be used, such as rivets, clamps or embossed grooves, such as toxes. To set gap A at one side of a laminated element wider than gap B at another side thereof, all that is required is to select the depth of the recess 3 to be different in the two regions.

In the present example, the laminate thickness of the thin metal sheet of aluminium lies between 0.3 and 0.7 mm, although the invention is not limited thereto. In the exemplary embodiment, both sheets 1, 2 can be of identical thickness, and it is not necessary to weld at all points of contact.

In the embodiment shown in Fig. 2, the carrier sheet 1 and the metal sheet 2 are both of aluminium and of the same thickness. In this case, both sheets are provided with specially formed recesses 3 and connected at the points of contact by welding at the welding points 4. Again, it is not necessary to weld at all contact points.

In Fig. 3, representing an edge area of a laminated element as in Fig. 1, the edge of one of the sheets, in this example the carrier sheet 1, is folded up and over the edge of the thin metal sheet 2 and flanged therearound as a sealing edge 5. If required, a connection between the edge 5 of the support sheet 1 and the covered edge of the metal sheet 2 of aluminium can be made by welding or by soldering with a solder which will not melt upon application of heat at the place of operation.

In the embodiment of Fig. 4, the carrier sheet 1 of aluminium has a thickness of between 0.3 and 0.7 mm. At a distance therefrom is the thin metal sheet 7, which is also of aluminium, having a thickness of between 0.05 and 0.1 mm.

This metal sheet 7, also described as "foil" or "thin strip", is provided with recesses 8, which are spaced over the surface thereof and may have been made, for example, by embossing. A laminate of a central expanded metal sheet 9 of A1MgSi alloy, as described in the German Patent Specification 27 14 395, and two covering thin foil-like metal sheets 6, each with a thickness of between 0.01 and 0.1 mm is inserted between the carrier sheet 1 and the recesses 8. Accordingly, the thermally insulating laminated element is, in this embodiment, composed of a total of five laminates, which are all made of aluminium.

The laminated element of the invention is substantially better for recycling, by comparison with known laminated elements, particularly those with mineral spacers. When forming the deformable laminated element, it retains "air chambers", i.e. cavities between the individual components, which are of importance to its heat insulation, as the aluminium expanded metal layer 9 is so hard that it is not easily compressed during the forming process. In this respect, it differs substantially from the mesh structure described in the German Utility Model application 91 07 484.

The embodiment of the invention shown in Fig. 5 offers the additional advantage of not only thermally insultating, but also being acoustically effective in the sense of better sound absorption. For this purpose, the thin metal sheet 16 is provided with holes 11 which are sufficiently large for sound to pass through and reach an aluminium fibre mat which forms the spacer between the carrier sheet 1 of aluminium and the sheet 16.

The connection between carrier sheet 1 and the thin metal sheet 2, 7 in Figs. 1 to 4 can also be established by way of rivets and/or metal clamps, which in particular engage at the edges of these two parts; these edges can be compressed outside the spacers.

Claims

1. A thermally insulating laminated element comprising a carrier sheet of aluminium and a thin metal sheet of aluminium which is held at a distance from the carrier by spacer means which are also made of aluminium, characterised in that the spacer means are formed by recesses in the thin metal sheet and/or in the carrier sheet, and/or by a mat of aluminium fibre, and/or by a laminate of aluminium expanded metal.

2. A laminated element as claimed in claim 1 wherein the spacer means is a laminate of aluminium expanded metal and an additional thin aluminium layer is inserted between the aluminium expanded metal layer and the carrier sheet and/or the thin metal sheet.

3. A laminated element as claimed in claim 1 or 2 wherehin the thin metal sheet is provided with holes which allow sound to pass through.

4. A laminated element as claimed in any preceding claim wherein the thin metal sheet is connected to the carrier sheet by welding points.

5. A laminated element as claimed in any preceding claim wherein the thin metal sheet is connected to the carrier sheet by a flanged edge of one of these sheets.

6. A laminated element as claimed in any preceding claim wherein the thin metal sheet is between 0.05 and 0.5 mm thick.

7. A laminated element as claimed in claim 6 wherein the thin metal sheet is between 0.05 and 0.1 mm thick.

8. A laminated element as claimed in any preceding claim wherein the thin metal sheet is connected to the carrier sheet by way of rivets and/or metal clamps which are particularly effective in the edge region.

9. A thermally insulating laminated element substantially as hereinbefore described with reference to and as illustrated by any one of the accompanying drawings.